EPA542-B-97-QQ6
May 1998
INNOVATIVE SITE
REMEDIATION
TECHNOLOGY
DESIGN & APPLICATION
Liquid
Extraction
Technologies
Prep ared by the Anierican Academy of Environmental
Engineers under a Cooperative agreement with the U.S.
Environmental Protection Agency
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INNOVATIVE SITE
REMEDIATION TECHNOLOGY:
DESIGN AND APPLICATION
LIQUID EXTRACTION
TECHNOLOGIES
Soil Washing
Soil Flushing
Solvent/Chemical
One of a Seven-Volume Series
Prepared by WASTECHฎ, a multiorganization cooperative project managed
by the American Academy of Environmental Engineersฎ with grant assistance
from the U.S. Environmental Protection Agency, the U.S. Department of
Defense, and the U.S. Department of Energy. .
The following organizations participated In the preparation and review of
this volume:
Air & Waste Management
Association
P.O. Box 2861
Pittsburgh, PA 15230
Hazardous Waste Action
Coalition
1015 15th Street, N.W., Suite 802
Washington, D.C. 20005
American Academy of
Environmental Engineersฎ
130 Holiday Court, Suite 100
Annapolis, MD 21401
American Society of
Civil Engineers
345 East 47th Street
New York, NY 10017
Soil Science Society
of America
677 South Segoe Road
Madison, WI 53711
Water Environment
Federation
601 Wythe Street
Alexandria, VA 22314
Monograph Principal Authors:
Michael J. Mann, P.E., DEE, Chair
Richard J. Ayen, Ph.D. Mark Meckes
Lorne G. Everett, Ph.D. Richard P. Traver, P.E.
Dirk Gombert H, P.E. Phillip D. Walling, Jr., P.E.
Chester R. McKee, Ph.D. Shao-Chih Way, Ph.D.
Series Editor
William C. Anderson, P.E., DEE
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Contents: [2] Chemical treatment
1. Soil remediationTechnological innovations. 2. Hazardous waste site remediation-
Technological innovations. I. Weitzman, Leo. n. Jefcoat, Irvin A. (Irvin Ally) III. Kim, B.R.
IV. WASTECH (Project)
TD878.I55 1997
628.5'5-dc21 97-14812
. ' " ' ' dp ^' ' ' ," '";"""
ISBN 1-883767-17-2 (v. 1) ISBN* 1-883767-21-0 (v. 5)
ISBN 1-883767-18-0 (v. 2) ISBN 1-883767-22-9 (v. 6)
ISBN 1-883767-19-9 (v. 3) ISBN 1-883767-23-7 (v. 7)
ISBN 1-883767-20-2 (v. 4)
Copyright 1998 by American Academy of Environmental Engineers. All Rights Reserved.
Printed in the United States of America. Except as permitted under the United States
Copyright Act of 1976, no part of this publication may be reproduced or distributed in any
form or means, or stored in a database or retrieval system, without the prior written
permission of the American Academy of Environmental Engineers.
'iii In ' -i
The material presented in this publication has been prepared in accordance with
generally recognized engineering principles and practices and is for general informa-
tion only. This information should riot be used without first securing competent advice
with respect to its suitability for any general or specific application.
The contents of this publication are not intended to be and should not be construed as a
standard of the American Academy of Environmental Engineers or of any of the associated
organizations mentioned in this publication and are not intended for use as a reference in
purchase specifications, contracts, regulations, statutes, or any other legal document.
No reference made in this publication to any specific method, product, process, or
service constitutes or implies an endorsement, recommendation, or warranty thereof by the
American Academy of Environmental Engineers or any such associated organization.
Neither the American Academy of Environmental Engineers nor any of such associated
organizations or authors makes any representation or warranty of any kind, whether
express or implied, concerning the accuracy, suitability, or utility of any information
published herein and neither the American Academy of Environmental Engineers nor any
such associated organization or author shall be responsible for any errors, omissions, or
damages arising out of use of this information.
Printed in the United States of America.
WASTECH and the American Academy of Environmental Engineers are trademarks of the American
Academy of Environmental Engineers registered with the U.S. Patent and Trademark Office.
Cover design by William C. Anderson. Cover photos depict remediation of the Scovill Brass Factory,
Waterbury, Connecticut, recipient of the 1997 Excellence in Environmental Engineering Grand Prize
award for Operations/Management.
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CONTRIBUTORS
PRINCIPAL AUTHORS
Michael J. Mann, P.E., DEE, Task Group Chair
ARCADIS Geraghty & Miller, Inc.
Richard J. Ayen, Ph.D. Mark Meckes
Waste Management Inc. USEPA
Lome G. Everett, Ph.D. Richard R. Traver, P.E.
Geraghty & Miller, Inc. Bergmann USA
DirkGombertn,P.E. Phillip D. Walling, Jr., P.E.
LIFCO E. I. DuPont Co. Inc.
Chester R. McKee, Ph.D. Sh:ao-Chih Way, Ph.D.
In-Situ, Inc. In-Situ, Inc.
The Soil Washing section was coordinated by Michael J. Mann, P.E., DEE, the Soil
Hushing section coordinated by Chester R. McKee, Ph.D., and the Solvent/Chemical
section coordinated by Steering Committee Liaison Clyde J. Dial, P.E., DEE, Scientific
Applications International Corporation (SAIC).
REVIEWERS
In addition to the reviewing organizations indicated on pages v and vi, the mono-
graph was reviewed under the auspices of the Project Steering Committee review panel,
Chaired by Peter W. Tunnicliffe, P.E., DEE, Camp Dresser & McKee Inc.
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This monograph was prepared under the supervision of the WASTECHฎ Steering
Committee. The manuscript for the monograph was written by a task group of experts
in chemical treatment and was, in turn, subjected to two peer reviews. One review was
.coMuctied under the auspices of the Steering Committee and the second by professional
and technical organizations having substantial interest in the subject.
Frederick G. Pohland, Ph.D., P.E., DEE Chair
Weidlein Professor of Environmental
Engineering
University of Pittsburgh
Richard A. Conway, P.E., DEE, Vice Chair
Senior Corporate Fellow
Union Carbide Corporation
William C. Anderson, P.E., DEE
Project Manager
Executive Director
American Academy of Environmental
Engineers
Colonel Frederick Boecher
*U.S. Army Environmental Center
Representing American Society of Civil
Engineers
Clyde J. Dial, P.E., DEE
Manager, Cincinnati Office
SAIC
Representing American Academy of
Environmental Engineers
Peter B. Lederman, Ph.D., P.E., DEE, P.P.
Center for Env. Engineering & Science
New Jersey Institute of Technology
Representing American Institute of Chemical
Engineers
George O'Connor, Ph.D.
University of Florida
Representing Soil Science Society of America
George Pierce, Ph.D.
Manager, Bioremediation Technology Dev.
American Cyanamid Company
Representing the Society of Industrial
Microbiology
"'"' !':" ' ', IT1 I1'':1:,! ''": ""? '. '".i.1"''. "J
Peter W. Tunnicliffe, P.E., DEE
Senior Vice President
Camp Dresser & McKee, Incorporated
Representing Hazardous Waste Action
Coalition
Charles O. Velzy, P.E., DEE
Private Consultant
Representing, American Society of
Mechanical Engineers
timothy B. Holbrook, P.E.
Engineering Manager
Camp Dresser & McKee, Incorporated
Representing Air & Waste Management
Association
Joseph F. Lagnese, Jr., P.E., DEE
Private Consultant r
Representing Water Environment Federation
Calvin H. Ward, Ph.D.
Foyt Family Chair of Engineering
Rice University
At-large representative
Walter J. Weber, Jr., Ph.D., P.E., DEE
Gordon Fair and Earnest Boyce Distinguished
Professor
University of Michigan
Representing Hazardous Waste Research Centers
FEDERAL REPRESENTATION
Walter W.Kpvalick, Jr., Ph.D.
Director, technology Innovation Office
U.S. Environmental Protection Agency
"ซ n u , ' H i; , : ' i i ' ,
George Kamp
Cape Martin Energy Systems
U.S. Department of Energy
I
Jeffrey Marqusee
Office of the Under Secretary of Defense
U.S. Department of Defense
;l|(S|1'tyn|, "; ' \if\\ !: 'i11'"1' ; " ^'V ' .'" " "
timothy Oppelt
Director, Risk Reduction Engineering
Laboratory
U.S. Environmental Protection Agency
1 ' f ilf
IV
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REVIEWING ORGANIZATIONS
The following organizations contributed to the monograph's review and acceptance
by the professional community. The review process employed by each organiza-
tion is described in its acceptance statement. Individual reviewers are, or are not,
listed according to the instructions of each organization.
Air & Waste Management
Association
The Air & Waste Management
Association is a nonprofit technical and
educational organization with more than
14,000 members in more than fifty
countries. Founded in 1907, the
Association provides a neutral forum
where all viewpoints of an environmen-
tal management issue (technical,
scientific, economic, social, political,
and public health) receive equal
consideration.
Qualified reviewers were recruited
from the Waste Group of the Technical
Council. It was determined that the
monograph is technically sound and
publication is endorsed.
American Society of Civil
Engineers
The American Society of Civil
Engineers, established in 1852, is the
premier civil engineering association in
the world with 124,000 members.
Qualified reviewers were recruited from
its Environmental Engineering Division.
ASCE has reviewed this manual and
believes that significant information of
value is provided. Many of the issues
addressed, and the resulting conclu-
sions, have been evaluated based on
satisfying current regulatory require-
ments. However, the long-term stability
of solidified soils containing high levels
of organics, and potential limitations
and deficiencies of current testing
methods, must be evaluated in more
detail as these technologies are imple-
mented and monitored.
The reviewers included:
Richard Reis, P.E.
Fluor Daniel GTI
Seattle, WA
Carol Whitlock, P.E.
Merriam, KS
Hazardous Waste Action
Coalition
The Hazardous Waste Action
Coalition (HWAC) is the premier
business trade group serving and
representing the leading engineering
and science firms in the environmental
management and remediation industry.
HWAC's mission is to serve and
promote the interests of engineering and
science firms practicing in multi-media
environment management and
remediation. Qualified reviewers were
recruited from HWAC's Technical
Practices Committee. HWAC is
pleased to endorse the monograph as
technically sound.
The lead reviewer was:
James D. Knauss, Ph.D.
President, Shield Environmental
Lexington, KY
v
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!i,,,i 'i ' ', '! i , i , : J| ,, ',' ' '11, ,: !ป ," in,1 til f1 i, ,'',!'1,1 'i"i;i!'jn, i, ;i ' i; ,:!i'" i IB, >,,'' IL i, ,i , t;: ...nil ', ',',1," i,, , yiii', , iii.jii;: i, JIB, ',,11,,,:
Soil Science Society of
America
The Soil Science Society of
America, headquartered in Madison,
Wisconsin, is home to more than 5,300
professionals dedicated to the advance-
ment of soil science. Established in
1936, SSSA has members in more than
100 countries, The Society is composed
of eleven divisions, covering subjects
from the basic sciences of physics and
chemistry through soils in relation to
crop production, environmental quality,
ecosystem sustainability, waste
management and recycling,
bioremediation, and wise land use.
Members of SSSA have reviewed
the monograph and have determined
that it is acceptable for publication.
" : :ip , '" -' : !
Water Environment
Federation
The Water Environment Federa-
tion is a nonprofit, educational
organization composed of member
and affiliated associations throughput
the world. Since 1928, the Federation
has represented water quality
specialists including engineers,
scientists, government officials,
industrial and municipal treatment
plant operators, chemists, students,
academic and equipment manufac-
turers, and distributors.
Qualified reviewers were
recruited from the Federation's
Hazardous Wastes Committee and
from the general membership. It has
been determined that the document is
technically sound and publication is
endorsed.
"":' ' v, i,:;1., -, ,1,, 'i,,,111 , . '' ,-
The lead reviewer was:
David L. Russell, P.E.
Global Environmental Operations, Inc.
Lilburn, GA
vi
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ACKNOWLEDGMENTS
The WASTECHฎ project was conducted under a cooperative agreement
between the American Academy of Environmental Engineersฎ and the Office
of Solid Waste and Emergency Response, U.S. Environmental Protection
Agency. The substantial assistance of the staff of the Technology Innovation
Office was invaluable.
Financial support was provided by the U.S. Environmental Protection
Agency, Department of Defense, Department of Energy, and the American
Academy of Environmental Engineersฎ.
This multiorganization effort involving a large number of diverse profes-
sionals and substantial effort in coordinating meetings, facilitating communica-
tions, and editing and preparing multiple drafts was made possible by a
dedicated staff provided by the American Academy of Environmental Engi-
neersฎ consisting of:
1
i
William C. Anderson, P.E., DEE
Project Manager &. Editor
John M. Buteribaugh
Assistant Project Manager & Managing Editor
Kathleen Lundy Springuel
Robert Ryan
Editors
Catherine L. Schultz
Yolanda Y. Mciulden
Project Staff Production
J. Sammi Olmo
I. Patricia Vfofctte
Project Staff Assistants
vll
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TABLE OF CONTENTS
Contributors : ซi
Acknowledgments I vii
List of Tables xxi
List of Figures xxvi
1.0 INTRODUCTION 1.1
1.1 Liquid Extraction Technologies 1.1
1.1.1 Soil Washing 1.1
1.1.2 Soil Flushing 1.2
1.1.3 Solvent/Chemical Extraction .1.2
1.2 Development of the Monograph , 1.3
1.2.1 Background 1-3
1.2.2 Process 1.4
1.3 Purpose ; 1.5
1.4 Objectives 1.5
1.5 Scope 1-6
1.6 Limitations 1-6
1.7 Organization 1-7
Soil Washing
2.0 APPLICATION CONCEPTS
2.1 Scientific Principles
2.1.1 Background on the Development of Soil Washing 2.1
2.1.2 Fundamental Concepts
2.1
2.1
2.3
2.1.2.1 Concentration of Contaminants in the Fines 2.3
2.1.2.2 Volume-Reduction Potential 2.4
ix
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Table of Contents
2.1.2.3 Treatment or Disposal of Concentrates 2.5
2.1.2.4 Complications 2.6
2.1.3 Soil Characterization 2.7
2.1.3.1 Background Understanding of How a
Site was Contaminated 2.8
2.1.3.2 Sample Collection and Evaluation 2.8
2.1.3.3 Particle-Size Distribution by ASTM Method D422 2J9"
' ' '" i '" ": ' ':; "" :
2.1.3.4 Chemical Analysis of Materials Retained on Sieves 2.9
2.1.3.5 Important Conclusions that Need to be Drawn 2.11
2.1.4 Contaminant Occurrence 2.14
2.1.4.1 Modes of Contamination 2.14
2.1.4-2 Concentrations and Impacts 2.16
2.1.4.3 Removal Efficiencies 2.16
2.1.5 Soil Matrix/Contaminant Relationship 2.16
2.1.5.1 Bar Chart Representation 2.17
2.1.5.2 "Treatability" by Fraction 2.17
2.1.5.3 Volume-Reduction Potential 2.17
2.1.5,4 Screening Study Evaluation 2.18
i
2.1.6 Treatability Studies 2.19
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2.1.6.1 Essential Information 2.19
2.1.6.2 Limited-Need Information 2.20
2.1.6.3 Information That is Not Needed 2.20
24,7 Limitations of TreatabiHty Study Data 2.21
2.2 Potential Applications 2.22
2.2.1 Soil Types 2.22
2.2.2 Contaminants and Mixtures 2.24
2.2.3 Types of Sites Encountered 2.25
2.2.4 Limitations 2.26
2.3 Treatment Trains 2.27
2.3.1 Primary, Secondary, and Tertiary Treatment 2.27
I v
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Table of Contents
2.3.2 Unit Operations Approach 2.28
2.3.2.1 Prescreening 2.29
2.3.2.2 Feed Screening 2.29
2.3.2.3 Separation | 2.29
2.3.2.4 Sand Treatment 2.30
2.3.2.5 Fines Treatment 2.30
2.3.3 Linking Soil Washing to Other Technologies 2.31
3.0 DESIGN DEVELOPMENT 3.1
3.1 Remediation Goals 3.1
3.1.1 Proven Performance 3.1
3.1.2 Reliability 3.2
3.1.3 Regulatory Acceptance 3.2
3.1.4 Public Acceptance I 3.3
3.2 Design Basis 3.4
3.2.1 Design Information 3.4
3.2.1.1 Physical Characteristics of the Soil 3.4
3.2.1.2 Contaminant Occurrence 3.5
3.2.1.3 Level of Treatment 3.7
i
3.2.1.4 Site Conditions 3.9
3.2.1.5 Treatment Standards 3.12
3.2.1.6 Schedule 3.12
3.2.2 Data Collection 3.12
3.2.2,1 Remedial Investigation Information 3.12
3.2.2.2 Site-Soil Sampling Program 3.13
3.2.2.3 Treatability Studies 3.13
3.2.2.4 Pilot Studies 3.14
3.3 Design and Equipment Selection 3.15
3.3.1 Introduction 3.15
i
3.3.2 Unit Sizing 3.15
3.4 Process Modification 3.17
xi
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Table of Contents
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3.4.1 Soil Matrix Characteristics 3.18
3.4:1.1 Particle-Size Distribution 3.18
;'. " '.'.JJ1.; ;' "'"'' '" ''" 3.4.1.2 Contaminant Distribution i j ' '_' _ 3.19~'
3.4.1.3 Moisture Content 3.19
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3.4.1.4 Clay and Natural Organics 3.20
3.4.1.5 Oil and Grease 3.20
3.4.1.6 Volatile Organic Compounds 3.21
3.4-1.7 Radioactive Contaniinants 3.21
3.4.2 Physical Conditions 3.22
3.4.2.1 Temperature 3.22
'V:.-.'" , ,' -w, :" : , 3.4.2.2 Humidity " '; ' ":""":" ; 3.22
;:*;!:;''';'; . ' ., ' ;" '** .' ;' . '.' 1.4.23 Grade " '.'.'*. *'.': ' ['! '""',!""' '"' '*''"'. ' '"''3.23""
:JJ;K|." . ... , 111 ;Jj;', S! : ''. 3.4.2.4 Debris ' ;,_ .' 'Z'. 1 '.' ","|, '".''." ,'. 3..23,^..
?.f! ;'!.. ' ' " '-J- 3.4,2.5 Vegetation ' 3.24
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3.4.2.7 Sensitive Populations 3.25
3.4.2.8 Infrastructure 3.25
3.5 Pretreatment Processes 3.26
3.5.1 Debris and Vegetation Removal 3.26
3.5.1.1 Bar Screen Separation 3.26
3.5.1.2 Rotating Screen Separation 3.28
3.5.2 Feed Preparation 3.29
3.5.3 Gravel Separation 3.30
3.5.4 Separation of Fines from Sands 3.31
ซ;." ., -'"'"",'",-" -\$- ; 3.6 PqsttreatmentProcesses , ,rii , i i jivi ' , , ,3.32
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nil vp!:^'' "' ''":! I' 3.6.1 GasequsEmissions i _ ; .3.32,
3.6.2 Water Treatment 3,33
'i ' '
3.6.3 Dewatering Fines 3.34
3.6.4 Disposal 3.34
3.6.5 Equipment Decontamination 3.35
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Table of Contents
3.7 Telemetry, Process Control, and Data Acquisition 3.36
3.7.1 Benefits
3.7.2 Potential Applications
3.7.3 Meter Type
3.36
3.36
3.37
3.7.3.1 Conveyer Load Cells 3.37
3.7.3.2 Digital Doppler Meters 3.37
3.7.3.3 "Venturi" or Differential-Pressure Transmitters 3.38
3.7.3.4 pH Meters i 3.38
3.7.3.5 Temperature and Pressure Meters 3.38
3.7.4 Costs 3.38
i
3.8 Safety Requirements 3.39
3.8.1 General Considerations I 3.39
3.8.2 Identification of Safety Hazards in Design 3.40
3.8.3 Personal Protective Equipment and Worker Safety 3.41
3.8.4 Site Operations 3.43
3.8.5 Laboratory Operations 3.44
3.9 Specifications Development 3.44
i
3.10 Cost Data ; 3.47
3.10.1 Cost Variables 3.49
3.10.2 Capital Costs 3.49
3.10.3 Operating Costs 3.50
3.10.4 Support Costs 3.50
3.10.5 Materials Handling Cosits 3.51
3.10.6 Residual Disposal Costs 3.52
3.10.7 General and Administrative Costs, Overhead, and
Contingencies 3.52
3.10.8 Contractor Profit 3.52
3.10.9 Cost Estimating (Workshop) 3.52
3.11 Design Validation 3.53
3.12 Soil Washing Permitting 3.56
xiii
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Table of Contents
II II III I, 1 111. I
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3.12. 1 Pertinent Environmental Regulations 3.56
3.12.2 Permitting Issues 3.57
3.13 Performance Measures ' 3.61
3.14 Design Checklist 3.63
4.0 IMPLEMENTATION AND OPERATION 4.1
4.1 Implementation 4.1
4.1.1 Procurement Methods 4.1
4.1.1.1 Traditional 44
4.1.1.2 Design-Build/Operate 4.1
4.1.1.3 Design-Build-Construct-bperate 4.2
4.1.1.4 Contract Operations 4.2
4. 1.2 Contract Terms _ ri . ^ ............ ,, ....... ........... ; .,, , ........ r , _ 4,3
4, 1,2.1 Lump Sum Contract 4.3
4. 1.2,2 Cost Plus Fixed Fee 4.3
4. 1.2.3 Unit Price Contract 4.3
4. 1.3 Preferred Combination 4.4
4.2 Start-up Procedures 4.4
4.2.1 Startup 4.4
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4.2.2 Performance Optimization 4.5
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4.2.2.1 Field Pilot Study 4.5
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. , 4.2.2.2 Process Adjustments and Modifications . ''4.6
' ..... 4.2,3 Process Vah'dation " 4.6
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4.3 Operations Practices 4.7
'.-'"4.3.1 Process 'Control'.. 4.8
4.3.2 Process Upsets 4.8
4.3.3 Maintenance Requirements 4.8
4.3.4 Safety Practices 4.9
4.3.5 Laboratory Requirements 4.9
4.4 Operations Monitoring 4.10
4.4.1 Process and Instrument Diagram 4.10
xiv
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Table of Contents
4.4.2 Mass Balances 4.11
4.4.3 Representative Samples : 4.11
4.4.4 Parametric Testing ! 4.11
4.4.4.1 Screens 4.12
4.4.4.2 Cyclones and Classifiers 4.12
4.4.4.3 Attrition Scrubbing ( 4.12
4.4.4.4 Flotation , 4.12
4.4.4.5 Settling 4.12
4.4.4.6 Water Treatment 4.13
I ,
4.4.4.7 Solids Dewatering and Drying 4.13
4.5 Quality Assurance and Quality Control 4.14
4.5.1 Sample Collection Issues 4.15
4.5.2 Laboratory QA/QC Specifics .. i 4.15
4.5.2.1 Controls/Audits 4.16
4.5.2.2 Samples for Controls/Audits 4.16
4.5.3 Data Quality Criteria for Soil Washing 4.17
4.5.3.1 Types of Data 4.17
4.5.3.2 Data Quality Parameters 4.17
5.0 CASE HISTORIES 5-1
i
Soil Flushing
6.0 APPLICATION CONCEPTS 6.1
6.1 Soil Flushing Development 6.1
6.4 Limitations , . 6.16
6.4.1 Physical Heterogeneity 6.16
6.4.2 Nonaqueous-Phase Liquids (NAPLs) 6.18
6.4.3 Diffusion of Contaminants into Inaccessible Regions 6.19
6.4.4 Sorption 6.19
6.4.5 Site Characterization 6.20
xv
-------
I'-' I!!1',;
Table of Contents
" Iliis" '! I:
i" !l I ' " In III'
if!1 Mill!'"' "" II' '
i i;'.
I i1 4 ;'
111)! ! ,:, in, ! :<
6.4.6 Chemical Loss
6.4.7 Innovative Technologies
7.0 DESIGN DEVELOPMENT
7.1 Remediation Goals
t,; , ; !' , ',;' ', ', , i"1 : ' '", ..
7.2 Design Basis
7.2.1 Site Characterization
7.2.2 Contaminant Containment
7.2.3 Saturated Zone Wellfield Design
7.3 Design and Equipment Selection
7.3.1 Well Recovery Rate and Injectivity
7.3.2 Formation Anisotropy
7.3.3 Streamlines and Pore Volumes
7.4 Process Modifications
7.4.1 Laboratory Tests
7.4.2 Soil Flushing Solutions
7.4.2.1 Organic Contaminants
7.4.2.2 Inorganic Contaminants
7.4.5 Soil Flushing in the Vadose Zone
I" ' ' t l" ;" I ".'
. 7.5 Pretreatment Process
7.6 Posttreatment Process
' I _ iiii'ii 'I,! '!'>, ! ' "';, '!"''''!' i"; . ,'. '!!,". ,|
7.7 Process Instruments and Controls
i 'i,, i in ,; - '; , i,'
7.8 Safety Requirements
7.9 Specification Development
7.10 Cost Data
7.11 Design Validation
7.11.1 Push-Pull Test
7.12 Permitting Requirements
7.13 Performance Measures
7.14 Design Checklist
6.20
6.21
7.1
7.1
7.5
7.5
7.10
7.10
7.13
7.14
7.14
7.15
7.17,'
i'v i ar <
7.17
7.18
7.18"
A j , I,!!,,;:,
7,21
7.33
7.38
7.39
7.40
7.40
'I
7.42
7.43
7.43
7.46
7.48
7.50
xvi
-------
Table of Contents
8.0 IMPLEMENTATION AND OPERATION 8.1
8.1 Implementation ***
8.1.1 Site Characterization 8.1
8.1.2 Wellfield Design 8.2
8.1.2.1 Bruni, Texas 8.5
8.1.2.2 Irrigary, Wyoming 8.6
8.1.2.3 Zamzow, Texas 8.7
8.2 Start-up Procedures 8.9
8.2.1 Baseline Water Quality 8.9
8.2.2 Equipment Shakedown and Calibration 8.10
i
8.3 Operations Practices ! 8.10
8.3.1 Pilot Tests i 8.10
8.3.2 Traverse City, Michigan Pilot Test 8.11
8.4 Operations Monitoring 8-12
8.4.1 Scope 8.12
8.4.2 Procedures 8.13
8.5 Quality Assurance/Quality Control 8.14
9.0 CASE HISTORIES 9.1
i
i
Solvent/Chemical Extraction
10.0 APPLICATION CONCEPTS j 10.1
10.1 Scientific Principles 10-1
10.1.1 Development of Solvent/Chemical Extraction 10.6
10.1.2 Fundamental Process Concepts 10.7
10.1.2.1 Amine Solvent Process 10.8
10.1.2.2 Supercritical Fluid/Liquefied Gas Processes 10.12
10.1.2.3 Drying/Extraction Process 10.14
10.1.2.4 Solvent Leaching Process 10.17
10.1.3 Soil Characterization 10.19
xvii
-------
Table of Contents
10.1.4 Contaminant Occurrence 10-?0
,' , '"; ' ,| " , , !,
10.1.5 Treatability Study Considerations 10.20
10.2 Potential Applications 10.21
10.2.1 Matrix Types 10.21
10.2.2 Contaminants and Mixtures 10-21
10.2.3 Site Types 10.22
10.3 Treatment Trains 10.22
11.0 DESIGN DEVELOPMENT / l'l'.r
11.1 Remediation Goals 11.1
..'"..' I ,.' ' ,''* f""',> " M I"-' '"' : / ' '' I wi-
ll. 1.1 Proven Performance 11.1
Hi ' i.
1" ["I',! If,!'
11,1.2 Reliability 11.3
11.1.3 Acceptance by Regulators 11.4
.11.1.4 Acceptance by the Public 11.5
\ 'iii " ,:,', ' i,.!'1'1'1'! '" .I i ' i " . Ji ii ' " ,i "'iป
11.2 Design Basis 11.6
" !,i.. ":i '" , , !ซ"i ' , ' i! ' ul"'"!', ' < . 1 ' ' "''.'. . '?' ''ป i iiiE'1
11.2.1 Required Design Information 11.6
11,2.1.1 Soil Physical Characteristics 11.6
11.2.1.2 Contaminant Type and Concentration 11.7
11.2.1.3 Approaches to Treatment " 11.7
11.2.1.4 Site Conditions 11.8
11.2.1.5 Treatment Standards 118
"'; ; ''"'''' ; 11.2.1.6 Schedule " t' ,,. ; *' ,|' .| '' ^ ",,'. ' J,f C
11.2.2 Data Collection 11.8
11.2.2.1 Treatability Studies 11.9
11.2.2.2 Pilot Studies 11.9
11.3 Design and Equipment Selection 11,10
11.4 Process Modification 11.11
11.4.1 Soil Matrix Characteristics 11.12
11,4.2 Physical Conditions 11.12
''i - , . ' ,.;' , .':!. . " :>,' ? ' 'i '' '"i (, ' ;.;: ' il, ,l"i:":l
xviii
-------
Table of Contents
11.5 Pretreatment Processes 11.12
11.5.1 Debris and Vegetation 11.12
11.5.2 Feed Preparation 11.13
11.6 Posttreatment Processes 11.13
11.7 Telemetry, Process Control, and Data Acquisition 11.14
11.8 Safety Requirements 11.15
11.9 Specifications Development 11.16
11.10 Cost Data 11.17
-
11.11 Design Validation 11.19
11.12 Regulatory Permits i 11.20
i .
11.13 Performance Measures 11-20
11.14 Design Checklist 11-20
12.0 IMPLEMENTATION AND OPERATION 12.1
12.1 Implementation 12.1
12.2 Start-up Procedures 12.1
12.3 Operations Practices j 12.1
12.4 Operations Monitoring 12.2
12.5 Quality Assurance and Quality Control 12.3
13.0 CASE HISTORIES 13.1
APPENDIX A: List of References A.I
XIX
-------
-------
LIST OF TABLES
i
Table Title Pjlge
3.1 Achievable Treatment Levels for Contaminants
3.2
3.3
3.4
3.5
3.6
5.3.1
5.13.1
5.13.2
5.13.3
5.14.1
5.14.2
5.15.1
5.16.1
6.1
Commonly Treated with Soil Washing
Common Soil Washing Equipment
Treatment Capacity of a 25 ton/hr Plant Under Various
Operating Schedules
Characteristics of a Successful "SE" Team
Typical Soil Washing Project Requirements and Detailed
Design Specifications
Validation Issues
Costs in $/ton for Operation of Various Sizes of Bergmann
USA/Soil Sediment Washing Systems
Cleanup Goals
Cleanup Standards Attained
Feed Concentration of Contaminants
Cleanup Goals
1
Cleanup Standards Attained
1
Cleanup Goals
Cleanup Results
Soil Flushing Critical Factors and Conditions
xxi
3.2
3.16
3.17
3.46
3.48
3.56
5.14
5.48
5.48
5.49
5.55
5.55
5.60
5.65
6.12
-------
I'!.:.
List of Tables
Table Tifle
6.2 Applications of Soil Flushing on General Contaminant
Groups 6.15
111 "ป ' ;i ป'i!' ! ij ,',',, ,! ' ' , ,! "ill/ ' 'IIP"'
6.3 Soil Flushing Applications at Superfund Sites 6.17
7.1 Relative Ease of Cleaning Up Contaminated Groundwater 73
i, -I... . ' -1ป. i t
-------
List of Tables
Table Tjtle. Esgง
9.4 Results of Column Leaching Tests 9.11
9.5 Summary of Presurfactant and Surfactant Soil
Flushing Results 9.14
10.1 Effectiveness of Solvent Extraction on General Contaminant
Groups for Soil, Sludges, and Sediments 10.23
i
11.1 Potential Applications of Commercial Solvent/Chemical
Extraction Processes H-2
11.2 Cost Comparison U.18
13.1 Physical and Chemical Characteristics of Untreated Soils 13.9
13.2 Pesticide Concentrations and Removal Efficiencies 13.17
i
13.3 Percentage of Screened Oversized Material 13.22
13.4 Process Conditions for all Test Runs , 13.24
13.5 PCB Removal Efficiencies 13.25
13.6 Oil and Grease Removal Efficiencies 13.25
13.7 Total Materials Balance 13.27
13.8 PCB Aroclor 1254 Matrix Spike/Matrix Spike Duplicate
(MS/MSD) Results 13.28
13.9 PCB Aroclor 1254 Field Duplicate Results 13.29
13.10 US EPA Best Demonstrated Available Technology (BOAT)
Standards for Refinery Hazardous Wastes K048-K052 13.35
xxiii
-------
It' ,
List of Tables
lilii'M"' ll'
V !;!' .1" *;j
ML:
, , II
table
Title
Page
!; ! I
13.1.1
13.12
13.13
13.14
13.15
13.16
Biotherm Process Analytical. Results After Three Laboratory
Solvent Extraction Steps on Al?I Separator Bottoms 13.36
13.19
* 13.20
::';:'
.. .
13.21
Biotherm Process Analytical Results After Three
Laboratory Solvent Extraction Steps on Refinery
(and Other Waste) Lagoon Sludge
Biotherm Process Analytical Results After Three
Pilot Plant Extraction Steps on Spent Drilling Fluids
(US EPA SITE Demonstration Program)
: til'1.
fV'
Biotherm Process Product W'ater Quality from Spent
Drilling Fluids (US EPA SITE Demonstration Program)
Biotherm Prcicess Analytical Results After Three
Extraction Steps on PCB Contaminated Soil
"! , , " ' ' !. ป ' 'In , ปl' 'I ' ,' 'I1 ' , II ' ' * ,' > 'il1'"
Effect of Water on Solvent Extraction on PCB's from
' , , V . . :" 'I ซ.: ' '' , ' .'' : V*'?".': l-BMI : '" i .' .
Contaminated Soil
Biotherm Process Economic Estimates Refinery
K-Wastes
13.18 Biotherm Process Economic Estimates Spent Drilling
," ", Fluids ' ' ' ..... ' " ......... ......... ' ! '".
1 .. ' ' '.,:,' . ' ..... i : ' I 'f :,' .
Extraction Sequence Used for Sediment A
Extraction Sequence Used for Sediment B
i' . '"i ' ' ," , . ; .;.' ,5 ...... r ,. ;, '.. I ,:
- ' , ..;' ' . ! ...... ' 1 ..... ....... . ! I :
Summary of Analyses Conducted for the RCC B.E.S.T .ฎ
SITE Demonstration ,
'-I11;,, ;., ' jit ' ....... , 'if .,'> " : (I, ..... i !;i , i;1, I ".i ,.i ;' , ' ' ji, <
'" '' ', ';, ' "" - '''''' : ... ;:- .' ' " ! " I ' ''' "
13.22 PAH Removal Efficiencies
13.37
13.41
,111 .-:. ii ' , .* i
13.42
13.43
"13.44"_
13.45
I iM" !'!n'l
13.4f'
13.57
13.58
',1,^ ซ i JIM :
13.60
' ;;'':: ll'i
13.62
xxiv
-------
ListofTabfes
Table
13.23
13.24
13.25
PCB Removal Efficiencies
Oil and Grease Removal Efficiencies
Triethylamine Concentrations Treated Solids, Product
Water, and Oil Phases
Page
13.63
13.64
13.65
XXV
-------
-!,r m
I I
Figure
2.1
2.2
2.3
3.1
3.2
3.3
3.4
3.5
3.6
3.7
6.1
6.2
6.3
LIST OF FIGURES
; . . ' i; i :
Title
Particle-Size Common Distribution
.," . ''. " [i ",'-.t :"r 'i'.': -if ?"'
Isolate the Target Fractions
-.; , .' . . ' "' :' -: ''.. '.: ,:::;, . ," hiiiR. I i'
Concentration vs. Particle-Size Distribution
Concentration vs. Particle-Size
Simple Separation
Simple Separation plus Sand Treatment
Simple Separation plus Sand Treatment plus
Fines Treatment
Debris Being Separated by Dumping Gross
Excavated Material on a Bar Screen with the. Bars
Appropriately Spaced
, . , ' ' ' : ; <; !': \'n"
Trommel
Wastech Soil Washing Cost Estimate Worksheet
Projection of Uranium Solution Mining Beyond the
Economic Cutoff
Projection of Enhanced Performance with Improved
Techniques Compared to Performance of
Pump-and-Treat Methods
.;.., '. : ; ,;,:.';., ' r-if,/ ;:: r. r\ .,
Projection of Enhanced Pump-and-Treat Contaminant
Recovery Performance with Improved Ckculation and
Surfactant Addition
2.10
11 . ฐ ;; r
' ""ป! ria, \. ""
2.12
2,13
3.6
_3.8
3.10
3.11
3.27
I . t ซ'
3,28
3.54
6.4
6.5
6.6
xxvl
-------
LJst of Figures
are Title
6.4 Projected Performance of Surfactant-Enhanced
Pump-and-Treat Methods Compared to Conventional
Methods for Removal of a Large Amount of DNAPLs 6.7
6.5 Cost Comparison of Conventional Pump-ahd-Treat
Methods to Other Available Technology 6.8
6.6 Schematic of Soil Flushing System 6.9
i -
6.7 Hydraulic Conductivity vs. Tension for Berino Loamy
Fine Sand and Glendale Clay Loam 6.14
6.8 Horizontal Wells Used in Soil Flushing 6.24
6.9 Extraction and Injection Horizontal Soil Flushing Wells 6.25
,i *
7.1 Hypothetical Contaminant Recovery from Two Wellfield
Patterns One Efficient and One Inefficient 7.11
7.2 Standard Wellfield Patterns : 7.12
7.3 Effects of Horizontal Directional Permeability 7.15
7.4 Stream Tubes Consist of a Series of Long Columns 7.16
7.5 The Effectiveness of Dishwashing Liquid in Removing TCE
from Contaminated Sand Under Laboratory Conditions 7.20
7.6 Results of Diesel Fuel Recovery Experiments
Using Surfactant, Water, and Drisipac Solution 7.25
i
7.7 Oxidation Potential and pH of Injected Solutions
and Pumped Solutions (Based on Equilibrium Data) 7.27
xxvii
-------
IIKilJ1 IJilllBIIPHB''*!!!11111' ", ' lilllll!; I, 'I'll' i' . ' !'! 'II'!1". i '''''illllllllllil1111' ' Illlllllll1!:1!!1" i * ''.mi'! T "i"]1 ;i iln,1.." ..l1!"1!!' , '"I1 .III in:'1 "' ' i'1 II111' ,'"' ' M 'I'11 , ! '" ซS i.:'"'!1" ' ' ,".'!li"! I Hi II1"' I 'III'I 1111 V.1' '.' "ป1B:'I Illป? ' if I '":i:ปi' '"Willi':*1 Jillll l^lr 1!|lซi' . II I'rll'"." ''N'lTOIIH'hi', ll
List of Figures
Figure Title. Page
7.8 Reduction of Total Dissolved Solids at a Restored In Situ
Uranium Solution Mining Site 7.29
7.9 Uranium-Contaminated Aquifer Restoration at an In Situ
Uranium Solution Mining Site 7.30
7.10 The In Situ Mining Process 7.31
7.11 Simplified In Situ Uranium Solution Mine Flow Sheet 7.32
,: ' ,:' ' i. L, " .1", ,,",: I I II , "!I ' '.' J ,i( ,,l
',' i. ;, ll11'1.1 . : '.' '.i ' ',1 ' ill ' ป J "ii:"1,' '.
7,12 Ion-Exchange Plant and Associated Equipment 7.33
7.13 Recovery of Contaminants by Pumping in the
Saturated Zone 7.34
7.14 Injection Well Design wim Two Horizontal Wells 7.35
.',.'", , " . I ; ' li ,,.,", , ,, ,!" ,'. .",,,,, , ',' ,'j illi'l ', ' r
7.15 Saturation in Silt Loam Using Two Horizontal Injection
Wells with Well Spacing at 10 m (30 ft) 7.36
7.16 Saturation in Silt Loam Using Two Horizontal Injection
Wells with Well Spacing at 20 m (60 ft) 7.37
7.17 Radial Flow to a Well in a Confined Aquifer 7.42
7.18 Present Worth as a Function of Percentage of Contaminant
Removed on Three Discount-Rate Curves 7.44
7.19 Range of Costs in Present Worth for the Year 1994
Based on Two Contaminant Removal Retardation
Factors of 99.9% and 90% 7.45
7.20 A Vertical Cross-Section of a Push-Pull Test Scheme in the
Injection Mode 7.46
xxviii
-------
List of Figures
Title | Page
7.21 Plan View of a Push-Pull Test in an Isotropic Formation 7.47
7.22 General Flow Chart for Permitting Requirements 7.49
i
8.1 Information Acquisition Sequence 8.3
8.2 Fourteen-Well Production Match, Bruni, Texas 8.4
8.3 Production Match to Fourteen-Well Pattern, Bruni, Texas 8.5
i
8.4 Five-Spot Production Match, Inigary, Wyoming 8.6
8.5 Production Match to Five-Spot Well Pattern,
Irrigary, Wyoming 8.7
8.6 Eleven-Well Production Match, Zamzow, Texas 8.8
8.7 Production Match to Eleven-Well Pattern, Zamzow, Texas 8.9
8.8 Multi-Aquifer Monitoring 8.15
i
9.1 Concentration vs. Pore Volume Extraction Curves 9.5
9.2 An Example of Mathematical Simulation of Surfactant
Washing of the Test Plot j 9.7
i
9.3 Mass Percent of PCBs and Oils Remaining in the Test Plot
After Phase I and Phase H Washings 9.9
,
9.4 Laboratory Column Study of Surfactant Washing of
PCB-Contaminated Soil 9.10
9.5 Measured PCE Saturation at the Location Near the
Center of the Test Cell Prior to Surfactant Flooding 9.13
xxix
-------
Ti I'Si I I' :.} Sit A
f Hi,,i,1' , ,j !! 'I,
si1' t >"". u
II (','
List of Figures
'". li'S!;? li'iL"!:."1'!!":1 , I ; I,:.,. . ( , .. : , rM! .,1 . : i
Figure litle
9.6 Fairchild Site Cleanup 9.15
" I
9.7 Hypothetical Projection of a Pump-and-Treat Case to
Emulate Cleanup of a Superfund Site 9.16
9.8 Time-Concentrated Plot of TCE and PCE in the Air-Stripper
Influent at the Savannah River Plant Site 9.18
9.9 History of TCA and PCE Variations in Extraction
Well GW32 (Six Month Average Concentrations) at
IBM-Dayton Site 9.21
"ITli1,.
9.10 History of TCA and PCE Variations in Extraction
Well GW25 (Six Month Average Concentrations) at
IBM-Dayton Site 9.22
10.1 General Schematic of a Standard Solvent Extraction Process 10.2
10.2 Cross-Current Extraction 10.4
" '- '. !? ; , ' II , . , ' ' "III!
10.3 Counter-Current Extraction 10.4
10.4 Generalized Diagram of the RCC B.E.S.T.ฎ Solvent
Extraction Process 10.10
10.5 Process Diagram Supercritical Fluid/Liquefied
Gas Process 10.13
I- -
10.6 Process Schematic Dryer/Extraction Process 10.15
,.,.,. . , I ...;
10.7 Process Schematic Solvent Leaching Process 10.18
, 'ill'- f ,!!!'in"",|!, .,;|i|,in i
13.1 Simplified Process Schematic Terra-Kleen
Extraction Process 13.6
XXX
-------
List of Figures
re Title Page
13.2 Effect of Extraction Cycle on the Concentration of PCBs
in Discharge Solvent 3.10
13.3 Oil and Grease Concentrations in Soil Before and
After Extraction 3.11
13.4 PCB Concentrations in Soil Before and After Extraction 13.13
13.5 Effect of Vapor Extraction on Residual Solvent 13.15
13.6 Effect of Biological Treatment on Residual Solvent 13.15
13.7 Location of the STDSuperfund Site 13.20
13.8 CFSฎ Process Diagram 13.21
13.9 PCB Removal Trend 13.30
i
13.10 Oil and Grease Removal Trend 13.31
i
13.11 Block-Flow Diagram of the Biotherm Process
for Refinery Sludge Treatment 13.33
i
13.12 Regional Location Map : 13.51
13.13 Experimental Design Flow Diagram 13.52
13.14 Generalized Diagram of the RCC B.E.S.T.ฎ Solvent
Extraction Process ! 13.54
xxxl
-------
* ' f
t f?
ill"!. I 1.' ' '
-------
Chapter 1
INTRODUCTION
This monograph covering the design, applications, and implementation of
Liquid Extraction Processes Soil Washing, Soil Flushing, and Solvent/
Chemical, is one of a series of seven on innovative site and waste
remediation technologies. This series was preceded by eight volumes pub-
lished in 1994 and 1995 covering the description, evaluation, and limitations
of the processes. The entire project is the culmination of a multi-organiza-
tion effort involving more than 100 expert!*. It provides the experienced,
practicing professional with guidance on the innovative processes considered
ready for full-scale application. Other monographs in this design and appli-
cation series and the companion series address bioremediation; chemical
treatment; stabilization/solidification; thermal desorption; thermal destruc-
tion; and vapor extraction and air sparging,,
7.7 Liquid Extraction Technologies
1.1.1 Soil Washing
I
Soil washing is an ex-situ, water-based process that employs chemical
and physical extraction and separation processes to remove organic, inor-
ganic, and radioactive contaminants from soil. It is usually employed as a
pretreatment process in the reduction of the volume of feedstock for other
remediation processes.
The contaminated soil is excavated and staged, pretreated to remove over-
sized material, and washed with water and, possibly, other cleaning agents to
separate and segregate the contaminants. 1'he process recovers a clean soil
fraction and concentrates the contaminants in another soil portion.
1.1
-------
Introduction
; f. IF in,, i
1
\.,"
'<' , ' ,,,',;, j. ;0;,ฃ>. :.j " i ,f "4:; !.ป ; r .' (.. "; - :"! ' 'I',,,4 "I"";;!!i ll
The principal advantage of soil washing lies in its ability to concentrate
contaminants in a residual soil as a pretreatment step, facilitating the appli-
cation of other remediation processes. In reducing the volume of soil that
must be treated, soil washing can reduce the overall cost. Soil washing per-
formance is highly sensitive to site conditions. The process is most effective
when applied to soils and sediments containing large proportions of sand and
gravel and is relatively ineffective when applied to soils having a high silt
and clay content.
1.1.2 Soil Flushing
Soil flushing is the enhanced in situ mobilization of contaminants in a
contaminated soil for the purpose of their recovery and treatment. Soil
flushing uses water, water with chemical additives, or gaseous mixtures to
accelerate one or more of the same geochemical dissolution reactions that
alter contaminant concentrations in groundwater systems. The process ac-
celerates a number of subsurface contaminant transport mechanisms that are
found in conventional groundwater pumping.
In general, soil flushing is most effective in homogeneous, permeable
soils, such as sands or certain silty sands. The process may be also effective
in the recovery of mobile degradation products formed after soil treatment
with chemical oxidizing agents and in the enhancement of oil recovery op-
erations. Effective application of the process requires a thorough under-
standing of the manner in which target contaminants are bound to soils and
of hydrogeologic transport. Depending on the matrix, organic, inorganic,
and radioactive contaminants are often amenable to soil flushing.
' ' r "" ;' ' |i ' '" ' '
1.1.3 Solvent/Chemical Extraction
Solvent/chemical extraction (SCE) is an ex-situ separation and concentra-
tion process in which a nonaqueous liquid reagent is used to remove organic
and/or inorganic contaminants from wastes, soils, sediments, sludges, or
water. The process is based on well-documented chemical equilibrium sepa-
ration techniques used in many industries, such as oil extraction from soy
beans, supercritical decaffeination of coffee, and separation of copper from
leaching fluids.
Solvent/chemical extraction can be differentiated from soil washing in
that soil washing involves the use of dilute aqueous solutions of detergents
1.2
-------
Chapter 1
or chelating agents to remove contaminants through dissolution, abrasion,
and/or physical separation, whereas SCE relies on the action of concentrated
chemical agents. \
Solvent/chemical extraction typically produces a treated fraction and a con-
centrated contaminated fraction, which requires further treatment to recover,
destroy, or immobilize the contaminants. It may concentrate contaminants by a
factor as high as 10,000:1 (although a concentration between 50:1 is much more
common), thereby, significantly reducing the volume of material requiring fur-
ther treatment or producing a concentrated stream for materials recovery.
7.2 Development of the Monograph
\
1.2.1 Background
Acting upon its commitment to develop innovative treatment technologies
for the remediation of hazardous waste sites and contaminated soils and
groundwater, the U.S. Environmental Protection Agency (US EPA) estab-
lished the Technology Innovation Office (TIO) in the Office of Solid Waste
and Emergency Response in March, 1990. The mission assigned TIO was to
foster greater use of innovative technologies.
In October of that same year, TIO, in conjunction with the National Advisory
Council on Environmental Policy and Technology (NACEPT), convened a
workshop for representatives of consulting engineering firms, professional
societies, research organizations, and state agencies involved in remediation.
The workshop focused on defining the barriers that were impeding the applica-
tion of innovative technologies in site remediation projects. One of the major
impediments identified was the lack of reliable data on the performance, design
parameters, and costs of innovative processes.
The need for reliable information led TIO to approach the American '
Academy of Environmental Engineersฎ. The Academy is a long-standing,
multi-disciplinary environmental engineering professional society with
wide-ranging affiliations with the remediaition and waste treatment profes-
sional communities. By June 1991, an agreement in principle (later formal-
ized as a Cooperative Agreement) was reached, providing for the Academy
1.3
-------
Introduction
I Si ;
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to manage a project to develop monographs providing reliable data that
Would be broadly recognized and accepted by the professional community,
thereby eliminating or at least minimizing this impediment to the use of
innovative technologies.
The Academy's strategy for achieving the goal was founded on a multi-
organization effort, WASTECHฎ (pronounced Waste tech), which joined in
partnership the Air arid Waste Management Association, the American Insti-
tute of Chemical Engineers, the American Society of Civil Engineers, the
American Society of Mechanical Engineers, the Hazardous Waste Action
Coalition, the Society for Industrial Microbiology, the Soil Science Society
of America, and the Water Environment Federation, together with the Acad-
emy, US EPA, DoD, and DOE. A Steering Committee composed of highly-
respected representatives of these organizations having expertise in
remediation techaology formulated the specific project objectives and pro-
cess for developmg the monographs (see page iv for a listing of Steering
Committee members). ^ "' "" ,", !', T
By the end of 1991, the Steering Committee had organized the Project.
Preparation of the initial monographs began in earnest in January, 1992, and
the original eight monographs were published during the period of Novem-
ber, 1993, through April, 1995. In Spring of 1995, based upon the reception
by the industry and others of the original "monographs', it was determined that
a companion set, emphasizing the design and application of the technolo-
gies, shoulcibe prepared" as well task Groups were identified during the
latter months of 1995 and work commenced on this second series.
1.2.2 Process , ' " ' ' , .. "_."" . "' .r' ' .. . / "".
For each of the series, the Steering Committee decided upon the technolo-
gies, or technological areas, to be covered by each monograph, the mono-
graphs' general scope, and the process for their 'development. The Steering
Committee then appointed a task group composed of experts to write a
manuscript for each monograph', tie task groups were appointed with a
view to Balancing the interests of the groups principally concerned with the
application of innovative site and waste remediation technologies indus-
try, consulting engineers, research, academe, and government.
The Steering Committee called upon the task groups to examine and ana-
lyze all pertinent information available within the Project's financial and
III
1.4
I I
-------
Chapter 7
time constraints. This included, but was not limited to, the comprehen-
sive data on remediation technologies compiled by US EPA, the store of
information possessed by the task groups' members, that of other experts
willing to voluntarily contribute their knowledge, and information sup-
plied by process vendors.
To develop broad, consensus-based monographs, the Steering Committee
prescribed a twofold peer review of the first drafts. One review was con-
ducted by the Steering Committee itself, employing panels consisting of
members of the Committee supplemented by other experts (See Reviewers,
page iii, for the panel that reviewed this monograph). Simultaneous with the
Steering Committee's review, each of the professional and technical organi-
zations represented in the Project reviewed those monographs addressing
technologies in which it has substantial interest and competence.
Comments resulting from both reviews were considered by the task
group, appropriate adjustments were made, and a second draft published.
The second draft was accepted by the Steering Committee and participating
organizations. The statements of the organizations that formally reviewed
this monograph are presented under Reviewing Organizations on page v.
1.3 Purpose
The purpose of this monograph is to further the use of innovative soil
washing, soil flushing, and solvent/chemical extraction technologies, that is,
technologies not commonly applied; where their use can provide better,
more cost-effective performance than conventional methods. To this end, the
monograph documents the current state of these technologies.
IA Objectives
The monograph's principal objective is to furnish guidance for experi-
enced, practicing professionals, and users' project managers. This mono-
graph, and its companion monographs, are Intended, therefore, not to be
prescriptive, but supportive. It is intended to aid experienced professionals
1.5
-------
Introduction
111!,1 '" '111
'ill liliil i " 1
in applying their judgment in deciding whether and how to apply the tech-
nologies addressed under the particular circumstances confronted.
In addition, the monograph is intended to inform regulatory agency per-
sonnel and the public about the "conditionsunder which the processes it ad-
;/ j";1 ; ;"!; *, i , i
dresses are potentially applicable.
7.5 Scope
The monograph addresses innovative liquid extraction technologies that
have been sufficiently developed so that they can be used in full-scale appli-
cations. It addresses all aspects of the technologies for which sufficient data
were available to the Liquid Extraction Task Group to briefly review the
technologies and discuss their design and applications. Actual case histories
were reviewed and included as appropriate.
The monograph's primary focus is site remediation and waste treatmerit
To the extent the information provided can also be applied elsewhere, it will
provide the profession and users this additional benefit.
Application of site remediation and waste treatment technology is site-
specific and involves consideration of a number of matters besides alterna-
tive technologies. Among;thernare the following that are addressed only to
me extent that theyare essential to understand tfie applicatioris and limita-
tions of the technologies described:
i i I'M ; ii;, 1" , Mih , .'. ', :<, '.'
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site investigations and assessments;
planning, management, and procurement;
regulatory requirements; and
community acceptance of the technology.
1.6 Limitations
The information presented in this monograph has been prepared in accor-
dance with generally recognized engineering principles an2 practices aiitH is
vr. ;;;; .. ":: '.':' 1 " :;, " '.,"' 1.6 ", ::'::!h;; '''"':"" '' ":; 1;": v:
-------
Chapter 1
for general information only. This information should not be used without
first securing competent advice with respect to its suitability for any general
or specific application.
Readers are cautioned that the information presented is that which was
generally available during the period when the monograph was prepared.
Development of innovative site remediation and waste treatment technolo-
gies is ongoing. Accordingly, post-publication information may amplify,
alter, or render obsolete the information about the processes addressed.
This monograph is not intended to be ami should not be construed as a
standard of any of the organizations associated with the WASTECHฎ Project;
nor does reference in this publication to any specific method, product, pro-
cess, or service constitute or imply an endorsement, recommendation, or
warranty thereof.
7.7 Organization
This monograph and others in the series are organized under similar out-
lines intended to facilitate cross reference among them and comparison of
the technologies addressed.
1.7
-------
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SOIL WASHING
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Chapter 2
APPLICATION CONCEPTS
2.1 Scientific Principles
2.1.1 Background on the Development of Soil Washing
Dutch Experience. Soil washing seems to have started as an environ-
mental remediation technology in The Nelherlands around 1982 or 1983.
The Netherlands has experienced significant economic and industrial devel-
opment over the past 300 years, resulting in contamination at about 10,000
Superfund-equivalent sites. Yet, The Netherlands has a land area of only
about 38,850 km2 (15,000 mi2)(about the size of Florida) and is the most
densely populated country in Europe. Because of the scarcity of land, the
treatment of contaminated soils to avoid land disposal is very important.
Soil management in The Netherlands has been a central factor in the suc-
cessful development of the country.
Remedial response at some of the first high-profile sites was undertaken
by a consortia of contractors and environmental companies. Nearly all
remediation activity in The Netherlands is controlled and paid for by the
government. The consortia interfaced directly with the responsible govern-
ment entities to begin work on treating soil to make significant volume re-
ductions in contaminated material and reuse "clean" products that met speci-
fied treatment standards. At about the same time these efforts got underway,
the Dutch government published treatment standards that could be applied to
any soil cleanup in The Netherlands. These standards, now modified several
times, have come to be known as the Dutch A/B/C levels. The standards,
which are based on a risk assessment of approximately 50 common organic
and inorganic elements and compounds, define what are known as action-
level concentrations ("C" level), limited reuse concentrations ("B" level),
2.1
-------
i i,
i" i:
Application Concepts
and unrestricted reuse concentrations ("A" level), implementation of this
system made it possible for technology developers and contractors to de-
velop, test, and invest in treatment units that could meet the targeted treat-
perfor-
. a sand,
could be reused in a limited manner after confirming that the appropriate
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concefltrations had been attained for the target contaminants. The limited
product reuse is generally as a construction-grade material for use as a road-
way sub-base, as clean backfill in construction projects, or as material incor-
porated into concrete and asphalt products.
Early soil washing projects in The Netherlands were not spectacular suc-
cesses. The first project was undertaken at a subsite of the famous "Dutch
Love Canal" at Lekkerkirke, near The Hague. The soil was contaminated
with several contaminants including arsenic, cyanide, a wide range of carci-
nogenic polynuclear aromatic compounds (PNAs), and pesticides. Not only
were ^^cqn^m^nants.dlffiiqul^tp^tfe^tj the concept of soil washing had not
been tested. The general concept initially was that the soil would be
prescreened to remove only the heaviest oversize material and then treated
with acids and surfactants to solubize the target contaminants and remove
them as a high-concentration wastewater. It was expected that this approach
would leave behind a clean soil an(i allow furjher treatment of the wastewa-
ter by traditional methods. It did not work that way. Although some of the
top companies were involved in this development, the project was a soil
washing treatment failure. Most of the material was eventually incinerated
or landfilled.
1 !"
The breakthrough in the development of soil washing in The Netherlands
came with a simple "paradigm shift." During early development of the tech-
nology, the central view had been that]the; treatment should focus on the
contaminant(s). It was assumed that if the contaminant was understood, a
method of dissolving, removing, or destroying it could be identified. The
important shift took place when it was discovered that the initial focus
Should be oil the soil. If the soil and its representative fractions could be
better understood, then treatment for the removal or destruction of the con-
taminants could be effected. /This,sbjr);^niithiinlg(ng led to the recognition that
soil washing could draw upon the proven experiences of the mining industry.
It also lecl to the development of a remedial technology that today represents
the central treatment approach in The Netherlands and Germany.
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2.2
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-------
Chapter 2
Current soil washing systems are based upon innovative uses of proven
mining equipment and processes. Soil washing is similar to mining in that
mining projects treat large volumes of ore to recover small amounts of prod-
uct relative to the feed. The valuable product is recovered, and the waste
ores, or tailings, are disposed. Soil washing is "reverse mining" in that large
amounts of feed soil are processed to generate a large volume of clean tail-
ings that can be reused or replaced on-site as backfill. The concentrates are
the contaminants that are removed and disposed.
i
2.1.2 Fundamental Concepts
Soil washing is an ex-situ, physical/chemical separation technology using
both particle separation and extraction processes to reduce contaminant con-
centrations. Water is the primary extracting medium. In the soil washing
process, a large fraction of the feed soil is treated to specified levels while
the contaminants are concentrated in the wash water or in a smaller fraction
of the feed soil. The concentrate, in either the water or soil, is then further
treated or disposed. The clean soil can be returned to the site of origin as
clean backfill without the need for long-term controls or monitoring.
Soil washing consists of prescreening of the excavated soil to remove
debris, treatment of the bulk soil, management of clean product, and the
further treatment or disposal of a much smaller volume of concentrate.
There are many potential arrangements for treatment unit operations, some
of which will be discussed in this chapter. It is important to understand that
the treatment steps used in soil washing are; not always the same. They are
often modified based on the soil and contaminants to be treated. Soil wash-
ing systems can draw on more than 20 possible unit operations. These may
be used in different configurations from site to site and from contractor to
contractor. Soil washing also interfaces easily with other technologies such
as extraction, thermal destruction, biological treatment, or stabilization, in
configurations known as "treatment trains.
2.1.2.1 Concentration of Contaminants in the Fines
Soil is often composed of gravel, sand, aind "fines", which are technically
defined as soil particles with an average size of less than 0.063 mm. There is
a general view that contaminants in soil are: always concentrated in the fines,
and that this must be true for soil washing to be applicable. This view is not
2.3
-------
IIIII I I "'if ; 1,Til! j|
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Application Concepts
always correct. The USDA system of soil classification (Agricultural Hand-
book No. 436 Soil Taxonomy) defines clay (<0.002 mm), silt (0.002-
0.050 mm), sand (0.050-2 mm), and gravel (2 mm-3 in.).
Contaminants that have come in contact with soils as a result of spills,
accidents, or long-term releases will generally accumulate on the fines be-
cause of the very large surface area and complex electrical and chemical
charges present in this fraction. The fines fraction has a surface area 10,000
times greater than the other soil fractions combined. However, this rule of
thumb does not mean that other soil fractions may not be contaminated at
levels that exceed the treatment standards. Each fraction (the gravel, sand,
arid fines) must be analyzed to determine where arid how the contaminants
reside in the various portions of the soil matrix.
If contaminants in all soil fractions exceed the treatment standard, this
does not eliminate soil washing as an option. It simply means that the treat-
ment must address each fraction. The soil matrix/contamhiant approach
allows the engineer/contractor to identify unit operations that may be applied
to the specific treatment problems posed by each fraction. If the oversize
fraction (gravel) is contaminated, mechanical screening or density separation
may be appropriate. The screened soil is then prepared for treatment by
separating the sand stream and the fines stream. The sand can then be
treated using attritioning, floatation, or density techniques. The fines can be
consolidated, treated, or disposed.
Soil washing unit operations, like those in mining, have an optimum
particle-size range in which they perform best. The challenge to the engi-
neer in treating contaminated soil is to match the optimum treatment unit
operation to the appropriate contaminated soil fraction.
2.1.2.2 Volume-Reduction Potential
Soil washing has an excellent ability to reduce the amount of soil that
must be treated or disposed in a remediation project. The goal of soil wash-
ing, as applied hi an on-site situation, is to separate and treat portions of the
feed soil so that it meets treatment standards and can be placed back on the
;,' i ., , s"1,,. ,, ,, ,; ,,, 'ป;':i "i"ii,,, ; ,j/ Vi/ ;';,,, ah!;;,; u. ,, MI, \ K "I'll;ซ,ป, ;,,,,., , , ,.IL ,,. ,, ,
site as "clean" soil without monitoring, capping, or other long-term controls.
Soil washing may also be implemented in a fixed-site mode, in which clean
soils are utilized as construction materials not backfilled on the remediated
site. The "volume reduction," expressed as a percentage, is defined as the
mass of soil (hi tons) returned to the site, divided by the mass of feed soil
' ' '' '.' 2.4 '"!" ' l '' ' '
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-------
Chapter 2
processed in the soil washing treatment unit. The amount of soil or debris
removed in the prescreening step is normally excluded from this calculation.
The following example is based on a site where 27,216 tonne (30,000 ton) of
material is excavated. The excavated material is screened through several steps
to remove debris, cobbles, construction waste, and other similar objects. The
average particle size of soil fed to a soil washing plant is less than 2 in. In this
example, 4,536 tonne (5,000 ton) are removed through the prescreening step,
leaving 22,680 tonne (25,000 ton) as feed to (the treatment plant. As a result of
treatment, 18,144 tonne (20,000 ton) are returned to the site after confirmation
that the treatment standards have been achieved. The volume reduction is
18,144tonhe/22,680 tonne (20,000 ton/25,000 ton) = 80%.
There is a common misconception that soil washing is not viable unless
the entire feed soil is rendered clean. It is important to recognize, however,
that if volume-reduction measures can be performed at a cost much lower
than the final remedy, soil washing as a volume-reduction step makes sense.
A good example of this situation can be illustrated by a site where the
fines mass constitutes 50% of the total feed soil (a relatively high level),
and the contaminants of concern require Incineration. Closer investiga-
tion reveals that the contaminants are concentrated in the fines, and that
mechanical screening and separation could achieve a 40% volume re-
duction for $110/tonne ($100/ton), compared to a cost of $l,099/tonne
($l,000/ton) for incineration. Clearly, soil washing as a volume-reduc-
tion tool makes sense in this situation.
i
2.1.2.3 Treatment or Disposal of Concentrates
Serious difficulty arises when any technology is expected to treat 100% of
the feed soils to levels attaining all of the treatment standards. The develop-
ment of remediation approaches unfortunately supports this misconception.
Landfilling has developed because it is based on a very simple proposition.
If waste is analyzed and shown to meet the waste-acceptance criteria, the
waste can be disposed in the landfill. Incineration can make the promise that
if the waste meets the feed criteria, incineration can destroy 99.9999% of the
hazardous organic constituents. If heavy metals are also contained in the
incinerator feed soil, incineration is no longer an option. This "either-or"
thinking does not allow the use of more cost-effective approaches that re-
quire multiple-step planning and treatment.
2.5
-------
Application Concepts
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Soil washing can be viewed most accurately as a soil pretreatment, often
rendering significant volume reductions, but also producing a small mass of
sibil with contaminant concentrations ranging from 3 to 10 times the bulk
soil concentration. The soil concentrates must be evaluated to determine
whether further treatment is feasible and cost-effective. The concentrated
contaminants are after in the fines, the most difficult fraction to treat. State-
of-the-art techniques often cannot fully treat this concentrated contaminant
mass, or, if they can, the cost may be prohibitive. The cheapest method in
many instances is to consolidate the fines and dewater the soil concentrate
into a sludge cake that can be disposed at an appropriate on-site, off-site
hazardous or npnhazardous waste landfill. Of course, the waste must be
"profiled," must meet the land disposal unit's waste-acceptance criteria, and
must not trigger any of the land disposal bans. Even with this approach,
disposal of the sludge cake will often be the highest individual component of
the overall cost of a soil washing remedy. Thus, it makes good sense to
determine what, if any, treatment can be applied to reduce the volume of
concentrated soil that must be disposed.
The remaining concentrated soil can then be evaluated based upon the
specific contaminants of concern and available, applicable technologies.
The most cornmon options are direct land disposal of the sludge cake, acid
extraction of heavy metals, bioslurry degradation of organics, and stabiliza-
tion of concentrated soil that contains metps and organics.
2.1.2.4 Complications
There are some potential complications that should be assessed when
evaluating the use of soil washing for a particular project. Some of the most
common concerns are presented below:
The Fines Fraction Seems Too Large. Conventional wisdom is
that soil witli greater than 30% fines (less than 0.063 mm) is not a
viable candidate for soil washing. This is not necessarily so. A full
evaluation and fair comparison of applicable technologies should
include the methods for handling various factions, the treatment
method proposed for the fines concentrate, and the cost-effective-
ness comparison to other available alternatives.
2.6
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Chapter 2
Fines are Difficult to Treat. Treating the fines is the most diffi-
cult treatment challenge in soils remediation. Contaminants in
this fraction are often bound into the lattice structure of the fines,
tightly held by chemical and electrical forces, and oxidized to
even more stable conditions. The ability to remove these con-
taminants must be confirmed in a rigorous treatability study.
More important, reviewing the laboratory findings must take into
account problems that may occur when operations are scaled up.
Nevertheless, difficulties in treating the fines should be viewed as
another step toward a complete solution, and, one that, although
difficult, should not negate the value of the volume-reduction
potential.
Other Fractions are Also Contaminated. Frequently, it is found
that contaminants in the sand and/or the oversize fraction also
exceed the required treatment standards. This does not mean soil
washing will not work. The nature and mode of contamination in
these other fractions must also be evaluated so that a treatment
process plan can be defined.
Whole Soils Make Treatment Very Difficult. Systems that attempt
to take the whole feed soil into a specific treatment unit are often
bound for failure. Mining and mineral processing engineers
learned long ago that treatment, removal, and concentrating pro-
cesses work best within a rather narrow range of particle sizes.
The challenge is to prepare the; feed stream to provide the opti-
mized particle-size range each treatment operation.
2.1.3 Soil Characterization
An important step in soil washing is the initial characterization of the site
and the soil to be treated. This does not mean that more time should be
spent on the remedial investigation (RI), nor does it mean that hundreds
more samples are required. In fact, most El reports do not present the infor-
mation required for soil washing or other treatment technologies. Only lim-
ited information is needed, but it must be collected and evaluated with treat-
ment in mind.
2.7
-------
Application Concepts
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2.1.3.1 Background Understanding of How a Site was
Contaminated
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It is important to understand how the site was contaminated. This infor-
mation can usually be determined from existing records, reports, and contact
with site personnel. This knowledge will assist the process engineer in
speculating as to the form of the contaminant on the affected soils. One
example is a steel mill that has soil contaminated with heavy metals. It is
likely that mill tailings and slag were disposed on the grounds, leading to a
first estimate that the soil contains free slag and particulate metals. At an
electroplating shop, heavy metals in the soil might be expected to include
metal hydroxide sludges because of the operations conducted there. The
metals could be bound in a lime precipitated mass. The difference in the
treatment approach is very significant. Spills of mobile liquids on the
ground around the plant can be expected to form a possible coating on the
sand and eventually become bound up in the fines. Understanding the basics
of the plant's operation or how wastes were disposed in the affected, area can
be very helpful in the first conceptualization of the problem.
2.1.3.2 Sample Collection and Evaluation
.111"'ill I P 1 ':,.'.' II 'ซ"
The soil washing process engineer should make use of existing data and
information to the maximum extent possible. The nature and extent of the
contamination at a site is usually well documented. Information that is often
missing includes the bulk location, the heterogeneity of the waste, the layer-
ing or pocketing of hot spots, and a physical view of how the waste is dis-
tributed in the soil.
i i ,:
The soil washing process engineer can find out about previous site
characterization efforts from the client or the consulting engineer. With
that information, conclusions can be drawn regarding the distribution of
wastes within the soils at the site. The site may be one large area with
relatiyely similar situations throughout, or there may be several subsites
where the wastes or the soil types are very different. Based upon this
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assessment^ specific locations can be identified where "representative"
samples may be collected.
Most RIs have been performed using borings as the method of choice to
collect soil samples. While this is useful for many applications, it is not
useful for technology process evaluations. Borings can give misleading
2.8
-------
Chapter 2
indications regarding the soil and the manner in which the contaminants are
disposed within the soil. If the auger hits rocks or cobbles, refusal can result
in missing hotspots that lie only slightly deeper. Visual indications of the
actual waste distribution are almost totally lost. For these reasons, it is rec-
ommended that test pits be used instead of borings. Test pits are open exca-
vations usually installed to depths of 0.61 to 3.05 m (2 to 10 ft). The re-
moved material is usually staged near the excavation site while observations
are made and soil is collected. The test pit provides a very good visual pic-
ture of the subsurface conditions while offering flexibility in choosing soil to
be taken as sample material. Appropriate safety practices must be followed
if persons enter pits over 1.5 m (5 ft) deep. The test pits can be sized as
required to obtain a good view of the actual remediation situation. Sample
material is collected and packaged in containers for shipment to the desig-
nated laboratory. Treatability study materials are exempt from permitting
requirements for quantities up to 10,000 kg (22,046 Ib).
2.1.3.3 Particle-Size Distribution by ASTM Method D422
The first step hi the sample evaluation is to perform a particle distribution
analysis. This is done by conducting a sieving study in accordance with
American Society for Testing and Materials (ASTM) Method D422 (ASTM
1963). The sieving is performed on wet material, and the water from the
sieving process is retained for analysis. Generally, 8 to 11 sieves are used,
ranging in size from 2 mm to 0.075 mm (200 mesh) on the bottom. After
sieving, the materials retained on each sieve are dried and weighed. The
data are plotted on a standard particle-size form. Results of a particle-size
distribution analysis are reported on a 100% dry solids (ds) basis. Field-
excavated soils are typically 80 to 85% dry solids; dewatered gravel is 95%
ds; dewatered sand about 90% ds; and sludge cake 45 to 55% ds.
2.1.3.4 Chemical Analysis of Materials Retained on Sieves
To correlate the distribution of the contaminants of concern to the soil
matrix, split samples of the materials retained on each sieve are forward
to a chemical laboratory for analysis. The quality of data required at
this stage will depend upon the ultimate use of the results. In most
cases, Contract Laboratory Program (CLP) level analytical procedures
are used, but extensive quality is not required. Based upon the US
EPA's treatability study guidance docuiments (US EPA 1991), a Level III
product is normally acceptable.
-------
Application Concepts
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2.10
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Chapter 2
2.1.3.5 Important Conclusions that Need to be Drawn
The first evaluation of the initial data will focus on soil type. The most fre-
quent inquiry can be answered by testing the percentage of soil mass in the fines
fraction. As seen in Figure 2.1, the ASTM interface between the fine sand and
the clays and silts is 0.063 mm (63 |Jm). All materials with an average particle
size <63 |um are generically referred to as fines. Particles with an average size
between 63 jam and 2 mm are referred to as coarse particles or sands. All par-
ticles >2 mm are referred to as oversize. The oversize fraction may contain a
wide range of particle sizes. It often is useful to break out another working
category of soil particle size. Since most treatments plants process soils with an
average size of <2 in., material in the oversize fraction that is >2 mm but <2 in.
is referred to as the "process oversize." All material >2 in. is generally referred
to as the "gross oversize." However, these cut points are not fixed. Some sites
may have a lot of construction debris, such as broken concrete rubble. In these
cases, it may make sense to define another fraction as that containing material
>8 in. (This is normally the largest size for a fixed-bar grizzly screen.) Other
sites may require a lower cut point for defining the fines fraction. (Hydro-cy-
clones can make process separations as low as 20 microns.) While the indi-
vidual cut points may vary, the important concept is that three or four fractions
(fines, sand, oversize, and/or gross oversize) must be measured and predicted
relative to their mass percentage contribution. The particle-size distribution
analysis can determine how much material must be handled, separated, and
treated in the process. As seen in Figure 2.1, the natural soil particle-size distri-
bution curve will have a reversed-S shape, with 5 to 30% of the soil generally in
the fines fraction. This is considered to be natural soil and a good candidate for
soil washing. There is nothing fixed about the upper limit of the percentage of
fines. The selection of a volume-reduction/treatment approach must be based
upon the merits of the site and the other remedial options available. However,
because sludges generally have a matrix of needy 100% fines and there is no
separation leverage, sludges are not normally considered good candidates for
soil washing.
In addition to evaluating the soil matrix, it is necessary to assess the con-
taminants and their concentrations. The chemical analytical data that were
derived from analysis of the materials retained on each of the sieves is plot-
ted or overlaid on the particle-size distribution curve. Useful ways of doing
this are shown in Figures 2.2 and 2.3. In Figure 2.2, the data are superim-
posed on the particle-size distribution curve, making it easy to identify
which fractions exceed the treatment standards.
2.11
-------
Application Concepts
I ]
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CM (D
Q) P
55
on
"3
2.12
-------
Figure 2.3
Particle-Size Distribution
50
CO
40,000
10,000
to
40,000
Size Fraction (microns)
O
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Application Concepts
2.1.4 Contaminant Occurrence
Once the concentrations of the contaminants of concern are quantified by
soil fraction, additional investigation must be performed to determine the
form, or modes, of contamination in each fraction.
2.1.4.1 Modes of Contamination
I The mode of contamination refers to the form and species of the contami-
nant and how it is associated with the three key soil fractions, namely, the
oversize, sands, and fines. The five primary modes of soil contamination are
free contaminants', particulates, coatings, bound contaminants, and soluble
material. Lead provides a simple example. Lead is a common contaminant
that can exist in the five modes. In the following example, lead is the con-
taminant of concern at a small-arms firing range that is undergoing
remediation. It is encountered in various modes in the fractions that are
being prepared as the soil is screened to remove the gravel and separate the
sands from the fines.
Free lead will be found in the oversize fraction as expended bullets and
lead slag. The bullets are discrete, visually identifiable, and can be easily
separated from the gravel fraction. The lead concentration in an individual
piece of bullet or slag will be extremely high, but on a mass basis, probably
does not represent a nigh percentage of the total soil mass. Mechanical
screening techniques are likely to be appropriate for the removal of this type
of free lead.
Particulate lead will be encountered within the sand fraction. Particulates
are defined in this sense as discrete constituents ranging in size from 75 to
150 pm. Particulate matter in this fraction may exist in a free state com-
mingled with the sand particles or lightly bound to the surface of a sand
particle. This is a common situation encountered hi1 mining applications. It
will prompt the process engineer to consider attritioning, flotation, and grav-
ity separation techniques. These unit operations will be discussed more fully
later in this chapter.
';) ' ."i ' , v ; " , " ,; -, ,i i:''- ' . If j i ;.' ',; " : ! >"
Sand will also contain coatings of lead (sometimes referred to as
"smears"). This occurs when a bullet fired into a sand berm thermally trans-
fers and coats some of the sand particles encountered at the bullet's surface.
The coating on the affected sand particles may be partial or complete. In
2.14
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Chapter 2
either case, the coating significantly changes the relative density of the par-
ticle. Thus, the process engineer may consider using this density difference
to separate the coated particles from the natural sands.
Bound contaminants refer to complexed species that are held by ionic,
van der Waals, or other electrical charges in or on the lattice structure of the
fines. The contaminants can exist in many species, such as oxides, carbon-
ates, or sulfates. The speciation of the contaminants can be determined
chemically and observed visually through the use of scanning electron mi-
croscopy (SEM). SEM, coupled with electron micro-probe quantitation can
actually identify the contaminant and determine its concentration. Then,
micrographs (photos) of the specific observations can be studied. The bound
contaminants exist in the fines fraction and, as mentioned earlier, represent
the most difficult treatment challenge. Treatment options for this fraction
will be discussed later in this chapter. In the firing range example, bound
lead will most commonly exist in the oxide form and tends to be removable
by acid-extraction techniques.
The contaminants of concern also exist in soluble forms, but this is less of
a concern for treatment than is commonly thought. In most cases, at the
U.S. Department of Energy (DOE), the U.S. Department of Defense (DoD)
sites and others being remediated under the Comprehensive Environmental
Response, Compensation and Liability Act (CERCLA) or the Resource Con-
servation and Recovery Act (RCRA), the soils being remediated have been
exposed to the environment in an uncontrolled situation for a long time. The
soluble constituents have usually been mobilized by rainfall, entered into
surface and groundwaters and been transported away from the soil
remediation site. Some soluble contaminants have the ability to reabsorb or
be converted, such as Cr3+ to Cr6*. Contaminants of concern that remain at
the site tend to be held in the soils in one of the modes discussed above.
Nevertheless, the soluble form must also be evaluated by the process engi-
neer. Soluble species that can commonly be of concern are volatile organic
compounds and organic pesticides. Should the soluble component be of
concern, sidestream wastewater treatment systems must be considered. In
the firing range example, lead is not particularly soluble and will not tend to
reconcentrate in recycle waters. The dredging of contaminated sediments
can result in anaerobic sediments becoming aerobic, resulting in the oxida-
tion and mobilization of metals. i
2.15
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Application Concepts
it , "i
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2.1.4.2 Concentrations and Impacts
Raw soil concentrations of the contaminants of concern can be helpful in
evaluating the suitability of this technology. Very high feed concentrations
often mean that a very high mass of the contaminant can be removed, but
that very low treatment standards may not be attainable. Very low feed con-
centrations may mean that low contaminant mass removal is possible, but
that very low treatment standards may be attainable.
Soil washing projects will generally be controlled by treatment standards
that are stated in the Record of Decision (ROD), legal administrative orders,
or other legal requirements. The ability to meet the" specified treatment stan-
dards for the fraction of the soil that is to be defined as "clean" will be the
determining factor in the volume reduction that can be obtained, and thus,
the relative success of the use of the technology. Therefore, the evaluation of
the soils will be based first and foremost on the ability of the treatment ar-
rangements to meet the treatment standards! In" some cases; however, the
treatment standards that have been calculated through risk assessment mod-
els are not practical or achievable in the real world. This is frequently ob-
served" in determining levels for pesticides or using background concentra-
tions as standards.
1 iiil! ซ ''.: ,,'i 'H .1,:,''. . mil " , , "' , '" , i' 'inf i " 'ii|F ,"!,. ! , || HI" , i" , , ii inn; i<
2.1.4.3 Removal Efficiencies
In some cases, it is practical to think in terms of the removal efficiency of
target contaminants^ In the wastewater inlustry, for example, treatment
requirements are often reflected in a removal of 90% of the biological oxy-
gen demands. In soil washing, removal efficiencies may vary from 50 to
99% or greater, depending upon the mode of contamination and the feed
concentration.
In a situation where a very low (and possibly impractical) treatment stan-
dard has been specified in a ROD or legal order, arid a reasonably high re-
moval efficiency can be demonstrated, it may be possible to petition for a
modified treatment standard.
.I!',.:* I'Till :!l(:[
2.1.5 Soil Matrix/Contaminant Relationship
Understanding the soil matrix/contaminant relationship is essential in
evaluating sites and their suitability for solid washing. This information will
form the basis for decisions regarding the process-flow arrangement and the
2.16
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Chapter 2
resultant costs. The evaluation will indicate which fractions are contami-
nated to levels above the treatment standards and which processes may be
required. Finally, the assessment will provide information regarding the
quality and quantity of residuals.
i
2.1.5.1 Bar Chart Representation
The soil matrix/contaminant information is normally presented graphi-
cally, either on the standard ASTM-D422 Form or in a bar chart. An ex-
ample of the ASTM form is shown in Figure 2.1. An example of the bar
chart method is shown in Figure 2.3.
2.1.5.2 "Treotablllty* by Fraction \
The soil washing process engineer must make several decisions based
upon the graphic and measured information presented. If free contaminants
exist in the gravel fraction, the engineer will further evaluate the nature of
the contamination and begin to consider additional treatment or study steps.
If no free contaminants are present, the gravel fraction can be removed by
mechanical screening. It is then staged, analyzed, and upon confirmation
that it meets the treatment standard, be placed back on the site. Evaluation
of the coarse fraction (the sands) will also dictate treatment requirements. At
about 30% of all sites, the sand fraction may not be contaminated, thus al-
lowing simple separation. If the sand is contaminated, as is the case at 70%
of the sites, treatment approaches must be considered. Similarly, contami-
nant levels in the fines fraction must be assessed for possible treatment or
disposal at an off-site facility.
2.1.5.3 Volume-Reduction Potential
Soil washing is part of an overall soil remediation strategy. Soil washing
does not have to solve the entire soil treatment problem. The volume-reduc-
tion potential, measured as the portion of the soil that can be returned di-
rectly to the site after simple separation and/or treatment of selected frac-
tions, should not be overlooked. When the soil washing portion costs less
than landfilling, a volume reduction of 50% may be very cost-effective even
when combined with off-site disposal at a landfill.
2.17
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:,: ...i
Application Concepts
2.1.5.4 Screening Study Evaluation
The process of conducting particle-size 'distribution and cnemical analy-
ses of the sieved fractions as described above, can be referred to as a soil
washing screening study. This screening study can be used as a "go/no go"
evaluation.'to decide whether more extensive testing;is justified. Several
important questions can be answered with mis basic information.
4 Is the soil matrix a good candidate for separation? The psaticle-
siz;e distribution curve will provide a good insight. If the fines
represent less than 30% of me soil, the site is probably a good
candidate. If the soil is 30 to 5^'&n^ it is probably &r^g?^
candidate, unless other remedial alternatives are limited or are
very expensive (e.g., incineration).
Do any fractions already meet the treatment standards? If a
fraction of significant mass already meets the treatment stan-
dards, then separation of that fraction, which is less costly, can
solve a significant portion of the remediation problem.
Does it appear that at least the sand and oversize fractions can
be treated? If fractions exceed the treatment standards but ap-
pear to be treatable, the situation is also promising.
What is the cost of soil washing at this site? To prepare a pre-
liminary cost estimate, the process engineer will need to know
me volume to be treated, the soil matrix/contaminant informa-
tion, the operating conditions and general requirements at the
site, and me final disposition of the fines concentrate. (Disposal
at a hazardous waste landfill is the default selection.)
How do soil washing costs compare to other viable alternatives?
To determine whether soil washing makes sense, the process
engineer must speculate as to what other options can be utilized
'"'' ' ' ' ih " , /" "_ at'the site.,, These rora^
and must address the volumes, treatment standards, arid capabiii-
: '" ' ".. '' ties for treatment. ' _ """ "'|' ^'^ ^ '''t' . '[ r ' "'
If the answers to the preceding questions are positive, soil washing de-
serves further consideration. In this case, a more detailed treatability study
will be required wherein each of the proposed unit operations are tested, a
complete process-flow diagram prepared, mass balances calculated, and
pricing refined.
" : ' : " :". " , '! . ' '' 2.18 ' '
it: r ,,j' ::: ,, ii ej; ,:!,; ,,ii,,;i ,-j,.,,, :,:;;,,; ,] : ป;,::. i . * "/ :, .,: ; ;:i!;ii ,, n r./1. it... i '.' ; m MI
-------
Chapter 2
2.1.6 Treatability Studies
Treatability studies are modeled principally after the US EPA's Guidance
for the Conduct of Treatability Studies (US EPA 1991). The document pro-
vides a generic approach to studies and sihould be used as a guideline, not a
definitive requirement. It provides a good overview of the technology and
outlines the approach to be taken in using treatability testing to evaluate a
soil washing remedy. The key steps include:
establishing the data quality objectives;
selecting a contracting mechanism;
issuing a work assignment; \
preparing a work plan;
preparing the sampling and analysis plan;
preparing the health and safely plan;
conducting required community relations activity;
complying with regulatory requirements;
performing the treatability study;
analyzing and interpreting the results; and
reporting the results.
2.1.6.1 Essential Information
The treatability study must address the collection, compositing, and use of
the feed soil, with convincing arguments that it is representative of the site to
be remediated. Taking only "hot-spot" samples to prove that the most
highly-contaminated soil can be treated is not effective since this will not be
the material actually treated. This kind of biased study will lead to mislead-
ing results and inflated costs. The study must define the soil matrix and the
relationship of the contaminants to the specific fractions that will be treated
in the proposed system. A process-flow diagram must be presented in detail
with the corresponding mass balance thai: adequately accounts for the soil
mass, the contaminant mass, and the water mass. The chemical data should
be prepared under reasonably good quality assurance (QA) procedures that
correspond at least to Level III as presented in US EPA's Guidance (US EPA
1991). (Level HI generally requires use of off-site analytical laboratories,
2.19
-------
Application Concepts
r is 11 'i
using detection limits similar to the CLP, and methods similar to, but not
exactly the same as, the CLP methodology. Rigorous quality assurance/
quality control (QA/QC) procedures are used, but a very detailed deliverable
package is not required.) It may also be helpful to consider using screening
tools that may be used in a full-scale implementation to begin making some
correlation with the developed data. These screening tools may include field
x-ray fluorescence (XRF), field gas chromatography (GC), or various colori-
metric tests.
These data and their evaluation should be presented with a cost estimate
that addresses all the elements of the remedial task, not just selected items,
so that the decision maker has a fair understanding of all cost elements to be
encountered.
i
2.1.6.2 Limited-Need Information
ii i
An example of information that may not be needed for standard applica-
tion is the extensive speciation of target contaminants when the process de-
sign does not require the information. For example, if concentrated sludge
cake is going to be disposed in a hazardous waste landfill, there is not much
value in determining the form of contaminants. What will be required are
the data needed to meet the landfill's waste-acceptance criteria, such as the
total concentration and Toxicity Characteristic Leach'ale Procedure (f CLP)
analyses for the targeted contaminants.
Yet, determining the forms of contaminant occurrence is important in
designing a system. Sequential extraction and scanning electron microscopy
are inexpensive and go a long way to define treatment requirements.
1 '; . ; ' :. ' I . /"i:/^',:;!;' 'i:'1:
2,1.6.3 Information That is Not Needed
, | '"' |ii,j".i | ,| ijji , | i | |,. ' ,"f i'ifl, !| ,:!"ป!if1 *,,,,
Generic guidelines often try to fit all technologies or treatment phi-
losophies under one umbrella. However, each step included in the
guidelines may not be needed in all applications. This is certainly the
case for soil washing. For example, when physical separation is used
for soil containing sand and gravel, it is not necessary to evaluate the
soil's cation exchange capacity if the separation data and the soil matrix/
contaminant information show that the sand and gravel meet the treat-
ment standards. Nor is it necessary in this case to define the number of
''wash stages" or the temperature of the wash.
2.20
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Chapter 2
2.1.7 Limitations of Treatability Study Data
Treatability studies are important. Few, if any, soil washing projects have
ever been performed without them. However, these studies must be viewed
in the proper context.
Treatability studies deal with small volumes of soil that commonly range
from 4.5-45 kg (10-100 Ib). A treatability study does not measure the per-
formance potential of a treatment system. It attempts to model the perfor-
mance based upon the experience of the contractor or technology developers.
Thus, it is important to factor this experience level into the overall assess-
ment of the validity of the results presented.
The mass balances for treatability studies conducted with small volumes
of soil often will not "close." This means that the soil mass, and most often
the contaminant mass, cannot be accounted for mathematically through the
individual treatment steps. A treatability study is essentially a batch-type
evaluation of each treatment step. The product from step 1 is treated in step
2, and so on through the system. The feed soil and product soil from each
step must be analyzed for the target contaminants to determine feed and
product concentrations. For small quantities of soil, the analytical
replicability of data is very wide. Thus, analyses of the same sample can
vary as much as 100% and still meet CLP analytical criteria. In this situa-
tion, the calculated mass balance does not close, and reviewers can mistak-
enly conclude that contaminants were "lost" in the study process. In the
mining industry, mass balances of this type are understood to be semi-quan-
titative; those that close to 50% or greater are generally acceptable. For this
reason, a treatability study can only imply a treatment validation and often
cannot confirm it.
Equipment cannot be observed hi operation during a treatability study.
Because of the difficulty in linking a successful treatability study to a full-
scale remediation, the contractor or technology developer will normally
consider a pilot-scale study or a demonstration of the site soils of concern on
an existing commercial plant. Pilot studies generally involve a continuous-
process system made up of the unit operations defined in the process-flow
diagram. Pilot studies have been conducted on as little as 91 tonne (100 ton)
of soil, generating the oversize, sand, and fines fractions. The benefits of
actually generating these products and allowing the ch'ent(s) regulators to
observe the operation, see the operating crew, and measure/analyze the prod-
ucts, cannot be overemphasized. In general, the larger the volume treated in
2.21
-------
Application Concepts
a pilot study, the better. To save money and obtain regulatory benefit, the
pilot study can be defined as an interim remedial action or the introductory
Step of a full-scale remediation. It is important to understand that the unit
treatment prices for a pilot study will differ from those encountered in a full-
scale project, because the cost is apportioned among the small number of
tons treated in a pilot study.
2f2 Pofentiat Applicafions
Soil washing has a broad range of potential applications. Yet, like any
technology, it is not right for all situations. The purpose of this section is to
define and discuss appropriate soil washing applications and areas where
limitations must be considered.
j
" 2.2.1 Soil Types ^ ......................... | ........................ .
The physical soil characteristics are the first considerations in determining
whether soil washing is the appropriate technology for a project. The fol-
lowing paragraphs identify several cornrrioh soil types and discuss how their
characteristics may help or hinder soil washing.
'',/i|Smwm^^ .......
il6% of the soil mass in the fines fraction, 60 to 80% of the mass in the
sand fraction, and 10 to 30% in the oversize fraction. This is the ideal soil
for soil washing and should result in significant volume reductions. This is a
common coastal soil found on both coasts of the United States.
' " PredominantlfCiay aซrfS% '&& ..... fhis class of soil will have >70<& of
the soil mass in the fines fraction, with the remaining 30% (or less) divided
among the sand and gravel fractions. This represents the most difficult soil
matrix for soil washing because very little volume-reduction leverage can be
attained, and the contaminants bound in the fines will be difficult to treat.
!! . .......... . ; * ' ,(< 1. 1 ; ..... \ji1|."1.fv',.vi.>.WPt ..... ' .- hSf 'I'"! Si- ; i,"K ' .'. ..... "!!' ' , '.' 'J' '.I;;T; , i" ........... .'*
Sand and Gravel Soils with Some Clay and Silt. This class of soils typi-
cally will have from 10 to 30% of the soif mass Tin the fines fraction, with the
balance of the material in the oversize and fines fraction. This soil type
represents themost common soil matrix for soil washing. This soil type
requires a screening study and probably a treatability study. A soil in this
i1 ,!>!! , '. ' . , i" ; ,1,! r ; ':; /,: . ;.. ' . -, '.{' ". ;,
. r. ' :; , .: ' . . ' , p 92
i 'i, ,;, , , "; ,' ji '
-------
Chapter 2
class may or may not be a good candidate for soil washing, depending upon
the contaminant concentration and occurrence, and competing remedial
I
alternatives.
Sand and Gravel with Significant Clay and Silt. This class of soil has 30
to 50% of the soil mass in the fines fraction, with the balance in the sand and
gravel fractions. This soil type represents the most marginal soil matrix for
soil washing. The process engineer may be inclined to dismiss this soil type.
Yet, evaluation may reveal that the contaminant situation is not particularly
difficult to treat with soil washing or that the competing remedial alterna-
tives are very expensive. Soils in this class should not be ruled out based on
the soil matrix alone.
Slags. Slags may be composed of ore wastes or process wastes from steel
or aluminum production. Slag is generally an oversize product >2 mm, but
it also contains secondary sand and fines constituents from contact or pro-
cessing breakdown. The slags are interesting because the contaminants are
usually bound in the slag itself. The fines may actually be the clean product,
in which case treatment will focus on processing the oversize fraction.
Mill/Mine Tailings. Mill and mining tailings may have characteristics
similar to a wide range of soil types. Depending upon the ore or the process,
the material may be primarily coarse-grained, as in the case of gold or ura-
nium mining, or it may be made up primarily of fines as in the case of coke
battery wastes. Tailings at least merit a screening study to determine the
mode of contamination.
Heavy Organic Soils. Heavy organic soils refer to soils that contain natu-
ral, not synthetic, organics, such as high levels of peat or other soil organics.
These soils can be very difficult to treat and are not particularly good candi-
dates for soil washing since the natural organics will foul screens, interfere
with separations, and even concentrate the target contaminants.
Sediments. Sediments in this context refer to materials dredged from
rivers, lakes, canals, and harbors. Sediments are often thought to consist
predominantly of fine-grained materials, but in reality can often contain as
much as 50% coarse-grained materials. Sediments with 30% of the mass in
the coarse fraction is rather common. Since water-bottom sediments are
encountered in very large volumes, the ability to make physical separations
and recover even 30% of the soil mass can be extremely attractive.
2.23
-------
, I'
11 !",n'J'
It;
Application Concepts
:"J '.,
2.2.2 Contaminants and Mixtures
'i. mi1.i '! i:
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A number of contaminant types and combinations pose challenges in soil
remediation. This section identifies the most common contaminant types
and their potential for treatment through soil washing. All of these types are
amenable to soil washing.
Hydrocarbons. Typical hydrocarbon contamination problems are caused
by spills from underground storage tanks, transport equipment, or from plant
operations. Hydrocarbons, including gasoline, diesel fuel, and JP-4, have
been routinely removed by various treatment companies on projects in the
U.S. and Europe. Heavier products, such as No. 6 Bunker "C" fuel oils, are
much more difficult to treat because they are more viscous.
Metals, Heavy metals are good candidates for treatment using soil
washing. The metals will tend to present themselves in many forms and
species. A screening study will indicate whether the soil matrix/con-
taminant relationship is suitable for this technology. In most cases, ex-
cellent removals can be expected. The most common metals for which
soil washing has been proved to be effective include lead, arsenic, chro-
mium, nickel, cadmium, zinc, and mercury.
PNAs. Polynuclear aromatic compounds (PNAs) have also been removed
effectively by experienced soil washing contractors. Common PNAs include
naphthalene, anthracene, phenanthrene, fluoranthrene, chrysene, and
benzo(a)pyrene. PNAs tend to be found as paniculate material in the sand
fraction, coatings on the oversize, and bound materials in the fines.
_ih M ; ' , ; , i ,;;;;, ;:::;'i;;i;::;!i! .",';;.!,;.;, , .,,;;"." . .; ;,; .:: ;"
Metals and PNAs. Metals and PNAs can be treated in the same soil
washing process stream. Soil washing, in fact, is the only remedial technol-
ogy that can treat organics and inorganics in the same pass through the treat-
ment system.
Pesticides. Some pesticides have been, shown to be effectively treated using
soil washing. Pesticides seem to exist as particles and adsorbed materials hi the
sand fraction, with some bound in the fines and some; that may be soluble.
Siciestream wastewater treatment may be necessary with this waste stream.
I
PCBs. Polychlorinated Biphenyls (PCBs) have been shown to exist in
i'"!1.,* , ii ,;, , ' If " , ' , "i|,,i ,, ;ซ; ,' ,,,.1,11!,, liliHi ,'Tniii ir ,, !<>H||, ป H, Illh n :- Jllimi,'. KnliHi: I ' ' 'if 'I "HflllB i ii I Ilk i ': '' n'l'in'Ml'iii'lH i, K ' i" , J1" ,:,"'i,,,,;"' 'i . il1 I ii1:1
soils in a manner similar to PNAs, Oily constituents may result in coatings
on the sand, while degraded components may be bound in the fines. Feed
concentrations hi the range of 200 to 500 mg/kg can be reduced to less than
5 mg/kg if the conditions are reasonably favorable.
, . ' '. .. ;v 2.24" ' '' '" | '' " ' '" : ' "
" ..;: ' 1, -; .;. V 'I V I,,. . tV-Vi ,. ii.' ; , Jill,*, ill,,, II1 iy',i,;iMr IF- ,ll ;!':; 1 ill" jjllt1,< '.*'.: ! ; ; ปIJ!" ;" , '":, ,1 -ti^ "
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-------
Chapter 2
LLRW. Low level radioactive wastes (LLRWs) exist in many forms
and result from many different operations. Most experience regarding
treatment of these contaminants has come from bench-scale and pilot-
scale studies performed at DOE weapons sites and ore processing sites
managed under the Formerly Utilized Sites Remedial Action Program
(FUSRAP). The most common contaminants include uranium, radium,
and thorium. Some work sponsored by the DOE, particularly at the
Idaho National Engineering Laboratory (INEL), and the Hanford facility
in Washington State, has addressed cesium.
VOCs. Volatile organic compounds (VOCs), particularly benzene, tolu-
ene, xylene, and ethylbenzene, are commonly encountered at remedial action
sites. Although soil washing systems can remove these contaminants, the
technology is not the first choice if VOCs are the only contaminants to be
treated. However, if VOCs are part of a more amenable feed stream, soil
washing techniques can provide excellent removals. Examples include
VOCs mixed with metals and/or PNAs.
i
2.2.3 Types of Sites Encountered
Chemical Plants. This class of sites is very diverse and can contain al-
most any media and contaminant combination. Contaminant sources typi-
cally encountered at chemical plants may include landfills, lagoons, spills,
excavated and staged soil, and contaminated fill. Almost any contaminant
can be encountered.
Refineries. Refineries contain many sources of contaminants that may
require remediation, including operating tanks and process units, lagoons,
storage tanks, land disposal units, and spilled materials. Contaminants are
usually hydrocarbon-based VOCs and semivolatile organic compounds
(SVOCs), sometimes commingled with heavy metals.
DoD Facilities. DoD facilities for the Army, Navy, Air Force, and Ma-
rines are most commonly contaminated by hydrocarbons in soils and
groundwater that resulted from spills and operations. Many specialty facili-
ties, however, handled a wide range of materials and wastes associated with
ammunition production and storage, maintenance activities, and training.
Remediation projects at DoD sites address combined wastes, including or-
ganics, PCBs, heavy metals, mercury, Her Majesty's Explosive/Royal
2.25
-------
..
Application Concepts
Division Explosive (HMX/RDX), and pesticides. Explosives are nitro aromat-
ics and include TNT and chemical agents and unexploded ordnance (UXOs).
DOE Sites. DOE sites are primarily affected by past activities associated
with nuclear weapons manufacturing. Large volumes of soil at these sites
have been contaminated with low-level radioactive wastes, primarily ura-
nium, plutonium, cesium, cobalt, and strontium, as well as organics, metals,
"-].. ;J'* and mixed wastes.' . " .. , ',,.. ',"", '', ",' ,, ' '.,
Harbors and Rivers. Sediments dredged during maintenance and
remediation activities at ports and harbors constitute a relatively new source
of contaminated materials. The soil matrix of these sediments is predomi-
nantly composed of fine-grained materials. The contaminant mix usually
contains a wide range of organics, heavy metals, PCBs, pesticides, and even
dioxins and furans.
2.2.4 Limitations
Soil washing can make a major contribution to reducing the volume of
contaminated material and treating contaminated soil, but it also has limita-
tions. The term soil washing implies that there is, in fact, soil to be treated.
In this context, "soil" refers to a distribution of oversize, coarse, and fine-
grained particles. If the target feed material consists solely of fines (e.g., a
typical sludge), soil washing is less applicable since there is no leverage to
separate the coarse and fine-grained materials. There is generally no ac-
cepted level representing a level of fines content above which soil washing
does not work. The acceptable upper limit fines in the soil will have to be
determined based on competing alternatives and economic comparisons. If
it is assumed that the only competing technology is excavation and disposal
at a hazardous waste landfill, then for a project involving 22,680 tonne
(25,000 ton) of material, the costs of soil washing would equal those of land-
fill disposal if the target material were composed of about 35% fines.
The key limitations associated with soil washing may arise if:
'" The soil matrix is not supportive of separation and treatment
because the fines concentration is too high or excessive amounts
of naturally-occurring organic materials are present in the soil.
j
The mode of contamination does not support removal from the
soil matrix. One practical example is a coating on sand particles
that cannot be removed.
,:M!": ;'!ซ .I: , - ' , ; " ซOA ' '":"' '
P M * - " ' . 2.2O
-------
Chapter 2
The feed concentrations are too high and/or the treatment stan-
dards are too low. Realistic removal efficiencies vary from 70 to
99% of the contaminant mass. A reasonable range of removal
efficiency is 80 to 95%. When 99.9% removal efficiency is re-
quired to meet the treatment standard, practical use of the tech-
nology is doubtful.
The comparative economics are not favorable. The most com-
mon limitation in the use of soil washing is based upon the com-
parative cost of other approaches. Soil washing must be more
cost-effective than competing treatment technologies, including
containment and disposal remedies.
Political decisions eliminate the treatment alternative. This may
occur in some cases because of local opposition to placing
treated soil back on the site.
2.3 Treatment Trains
A treatment train generally refers to multiple technologies used in serial
or parallel fashion to treat a particular feed stream. Soil washing is particu-
larly viable in treatment train arrangements because of its intrinsic capability
to prepare soils in fractions that are more amenable to further treatment.
2.3.1 Primary, Secondary, and Tertiary Treatment
Soil washing is not a fixed process in the sense that it always uses certain
unit operations in a prescribed order. Many unit operations are available in
soil washing and can be configured in many ways depending upon the soil
matrix/contaminant situation.
In the wastewater industry, treatment plants are commonly categorized as
primary, secondary, and tertiary treatment plants. A primary plant might
consist only of a clarifier and a discharge; weir. Secondary systems include
an activated sludge process with chlorination. A tertiary plant might add
carbon polishing. Primary systems have relatively low removal efficiencies,
but also have very low capital and operating costs. Secondary systems have
2.27
-------
Application Concepts
if* : iiil
I IK .'..,:' V;
improved removal efficiency, but at a higher cost. Tertiary systems can
achieve the highest possible removal efficiency, but at much higher costs.
Soil washing systems may also be configured in a manner analogous to
wastewater treatment plants. Primary soil washing systems consist of pri-
mary screening and separation. These might be used if the oversize and sand
fractions do not exceed the treatment standards. Primary systems might be
referred to as "straight separation" systems since they separate the sand and
gravel, concentrate the contaminants in the fines and produce a sludge cake
that can be disposed without further treatment. The unit operations are lim-
ited and removal efficiencies are not veiy high, but the sand and gravel meet
the required treatment standards. Unit costs are very low with this approach.
Secondary soil washing treatment consists of the primary treatment pro-
cess described above, with additional 'treatmentof'the sand fraction This
approach might be used in a situation where the gravel meets the treatment
standard upon separation, but the sand and the fines do not. The sand may
be treated using attritioning, froth flotation, and spiral concentration. The
fines are simply consolidated and dewatered into a sludge cake that can be
disposed off-site. The treatment efficiencies are improved, but the unit treat-
ment cost is higher than "straight separation."
Tertiary soil washing treatment consists of primary and secondary treatment,
with additional treatments of the fines fraction using bioslurry or extraction
processes to remove contaminants from this final fraction. The removal effi-
ciencies are very good, but the unit costs are the highest encountered.
Primary, secondary, and tertiary systems are all soil washing systems,
although they look quite different and will have significantly different costs.
The selection of the most cost-effective system will be based upon the soil
matrix/contaminant relationship and the treatment levels demanded at the
specific site.
2.3.2 Unit Operations Approach
;,; , ' ,;,i vi ; ' , ., * ''! '.,; i.,1-,!!- .. . , i ป(j- }>,!,:: ''.. i" i1 ,.. I'wl/i,*;''f ' " ' " l;";' ' I
There is no fixed arrangement of treatment steps that must be employed
for a system to qualify as soil washing. Many treatment techniques can be
usedv This oft-611 contrtbutes !ฐ a ^sund^PteBdJng of soil washing since the
process must be tailored to each application based upon the soil matrix/
contaminant relationship. Specific treatment steps that may be used are
i
2.28
-------
Chapt8r2
referred to as unit operations. Some of the unit operations frequently used in
soil washing are briefly described below.
2.3.2.1 Prescreening
Prescreening is performed to remove gross oversize produces) and to
prepare a feed to the soil washing plant. Debris removal can be conducted
by the excavation equipment. Very large debris can be staged separately.
"Grizzlies" are either fixed or vibrating bar screens with a typical cut
point of 8 in., 6 in., or 4 in. Most screening units are mobile. Material larger
than the selected cut point is rejected off the top of the screen, and material
below the cut point falls though the screen.
Trommel screens are mobile, rotating screens that can make a cut in the
range of 1 to 4 in. They are particularly useful in further treating the
underfall of a grizzly since they can prepare a separated product with rela-
tively little misplacement (when material from one product stream ends up
in another product stream due to equipment inefficiencies or changes in
operations or feed conditions). Any product larger that the cut point comes
off the end of the trommel while product smaller than the cut point drops
through the screen, usually onto a conveyor belt for staging.
2.3.2.2 Feed Screening
Feed screening is required to prepare soil to the size range that will sup-
port downstream treatment steps. It usually involves removal of the gravel
fraction from the sand and fines.
Mechanical screens are available in many designs. They may either be
fixed or vibrating, and generally are single- or double-decked. The "deck-
ing" refers to the screen itself, made of a long-wearing synthetic material
ranging in size from 2 to 20 mm.
Wet mechanical screens feature a series of water spray heads that wet the
feed soil and assist in cleaning the gravel. They can be used to prepare a
slurry of the sand and fines for pumping application.
2.3.2.3 Separation
Separation techniques are physical operations generally used in soil wash-
ing to prepare the sand and fines for further treatment. Separation tech-
niques need to be highly efficient and will be measured by the misplacement
2.29
-------
Application Concepts
;
of one fraction in the other. Less than 5% misplacement can be attained
consistently with the right techniques.
Fines screens can be used, but they are typically limited to about 500 um.
{ , ,;, ,i;|j(_ ,, ,, Fines sc|e|ns canjreof .s.tandard design, but ^ause of the s^l^decldng slots,
they must present a very large surface area to manage the flow. Curved screens
(or sieve bends) can also achieve reasonably low cut points.
Separators can be. used to separate coarse and fine-grained materials at
!!...">, ' : !:' :'" .{1,1 ,' II ;': selected cut points, but are more frequently used to control the dry solids
r''." ''//: cohcentratipn m me unit underflow. "" !
Hydrocyclones are physical separation devices. They are slightly differ-
ent from other separators in that they are vented and are designed to produce
a coarse product in the underflow, and a fine product and water in the over-
flow, at a very precise separation point, often within a selected cut point of
!" :::l +/- 0.003 mm. " "" '
,", in, ' ! ',. ;,,, , ,,i, ;,,, ' , I. ; ,:,,;"' "[ ' , j j| ป ,, ' i i
i; .! . ' || 1111 I I ' , i. , ', ป;, " ' ,''" M ,; i. i jip ,,, ,11,, | ; I , ' ,, i,i , i ปi , '" ', '"','' ,iin ,| , i'
".'" ?.3.2.4 Sand Treatment '_ ' ^' ''_'/_' _|' "
Treatment w,ill nprmally be performed on the separated sand stream since
the unit operations will perform more effectively within a specific size range.
Attritipnjng cells (sometimes referred to as high-intensity scrubbers) will
i'"1 , " i1" .''iiL!,,,!,!"1!1',*,,!' , I Illli'" I '"" ' ill' ii'il '' '''IH'1', '111!,' i "'' ,11' , i '""I, i Mil'H'",hi Nil'1 ' T '"'Hi/l'i'ii ,,i"i '','i' il/liiliiiin' nil" !' , '': ,"1111" ,' 'I'lllllCIU'luT !'!HI' , , m *f ,,r
drive the feed soil to |ts natural particle size and are used to breakdown soils.
The attrijipned product can be separated again to get the coarse and fine
particles in the right stream.
Density separation can be used to separate particles that have different
densities but approximately the same particle size. Typical units are spiral
|s'ii!'l! \, ;; ^;/;^/l;bncentrators ormu^-j^yity separators/'
Froth flotation units are frequently used with the support of specialized sur-
factants to remove paniculate or free contaminants from the sand fraction.
Dewatering of the sand is provided by vibrating sand dewatering screens.
Normally the water fraction is recovered for reuse in^ the treatment facility.
2.3.2.5 Fines Treatment
Treatment of the fines fraction will vary widely depending upon the soil,
the contaminants, and the contractor. As of this writing, three primary tech-
niques are being used.
2.30
-------
Chapter 2
Dewatering of a consolidated sludge fraction in preparation for
off-site disposal at an appropriate landfill.
Extraction using acids and chelates for removal, and sometimes
recovery, of the target contaminants.
Bioslurry degradation of the separated slurry to transform organic
contaminants in the fines fraction.
2.3.3 Linking Soil Washing to Other Technologies
The real power of this technology to emerges when the separation and
treatment capabilities of soil washing are linked to other technologies in
what is referred to as a treatment train. Some of the current technologies
that can be effectively linked to soil washing are:
Stabilization. Reagents or additives can be added to various soil
washing streams, mixed in existing or additional treatment units,
and dewatered using filter presses or centrifuges that are already
provided with the system. This technique may be most appropri-
ate to stabilize the sludge cake? to meet TCLP standards for place-
ment on-site or disposal off-site.
Low Temperature Thermal Treatment (LTJT). Soil washing can
reduce the quantity of the feed stream to the LTTT unit and better
prepare the feed stream for LTTT relative to concentration, soil
characteristics, and moisture content.
Vitrification. Soil washing makes an excellent first treatment step
for applications involving low-level radioactive waste by achiev-
ing volume reductions and concentrating contaminants into a
small fraction that can be easily and effectively fed to a vitrifica-
tion unit.
2.31
-------
III!
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-------
Chapter 3
DESIGN DEVELOPMENT
3.1 Remediation Goals
The remediation goals established for any specific project form the basis
for determining the applicability of any remedial technology. The ability of
soil washing to treat a broad range of contaminants, particularly its ability to
treat organics and inorganics in the same process stream, makes this technol-
ogy broadly applicable.
3.1.1 Proven Performance
Table 3.1 lists the contaminants most commonly treated with soil washing
and the reasonably achievable treatment levels (the "B" level) under the
Dutch ABC standards (described in Section 2.1.1). Although the Dutch
system has been recently revised, the "ABC" levels became widely known
and used. The B level can be thought of as an industrial use level. Although
these are the most commonly encountered contaminants, the list is not in-
tended to show all contaminants that can be treated with soil washing. In the
United States regulatory system, the treatment standards will be determined
by the completion of a site-specific risk assessment. The B levels are very
helpful, however, in making a first estimate of the resulting treatment level.
The most extensive database of performance information comes from soil
washing experience in The Netherlands and Germany, where the B levels are
routinely achieved, and in many cases, the "A" level (an unrestricted use
level) can be reached. The performance results of soil washing projects in
the United States are presented in Chapter 5, Case Histories.
3.1
-------
: I- -
l
Design Development
Achievable Treatment Levels' for Contamlnanfs
Commonly Treated with Soil Washing
1111 i ,,,:, n , .'.'ihppi i ' i.; ', ... r; ii : inigi i i inn IP in | 11 ,ป
_ , ___ _ , , ;- j -
Contaminant Dutch "B" Level (mg/kg)
Metals
Chromium 250
, i 'ป, ' in I ~ ... ,,1,l,l, ]: . u /" .|N.I;II ,: ;. i II
,;;,:, Nickel ' ' _'' ' ' 100
Zinc 500
'
Arsenic 30
Cadmium . 5
Mercury 2
Lead 150
Organics
Total Polynuclear Aromatics (PNAs) 20
Carcinogenic PNAs 2
;,_ PCBS , | 1
Pesticides (various) < 1
, ' '" , , i
Petroleum Hydrocarbons (TPH) 100
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-------
Chapter 3
DOE has undertaken a strong advocacy program through the EM-40
Technical Connections Program and through the EM-50 Office of Tech-
nology Development. These programs have been implemented with
support from Argonne National Laboratory and Sandia National Labora-
tory. These efforts have resulted in a significant commitment to soil
washing at DOE's Hanford (Richland, Washington) facility and Fernald,
Ohio facility and in the agency's Formerly Utilized Remedial Action
Program (FUSRAP).
The U.S. Department of Defense has also undertaken major soil washing
evaluation activities in each branch of the military. Significant activities
promoting the use of soil washing for specific applications are being under-
taken, including the U.S. Army Environmental Center in Aberdeen, Mary-
land, the U.S. Air Force Center for Environmental Excellence at Brooks
AFB in San Antonio, Texas, U.S. Navy's Naval Facilities Engineering Sup-
port Activity in Port Hueneme, California, and the U.S. Army Corps of Engi-
neers, Waterways Experiment Station, Vickisburg, Mississippi.
The combined result of these activities is that soil washing has become
acceptable to regulators and government entities, but always with the re-
quirement that the application be properly planned and managed.
3.1.4 Public Acceptance
Public acceptance of soil washing is also favorable. Soil washing has the
very positive attributes of being able to treal: soil, remove contaminants, and
allow the reuse of soil and other resources possibly recovered from the site.
There are few or no emissions problems related to the technology, and the
installation is a temporary one that remains only for the duration of the
project. Because soil washing can meet the required treatment standards, the
site is available for development or redevelopment without any additional
long-term controls.
Some problems with public acceptance might be encountered, but they
are generally similar to those related to the use of any pn-site treatment tech-
nology. Concerns that can be expected and should be addressed in a mitiga-
tion plan can include noise levels during operation, movement and control of
haul trucks on- and off-site, and the perception that no treatment level is
acceptable and, therefore, no treated product should be placed back on the
site. Overall, however, soil washing is considered a benign process and is
viewed enthusiastically.
3.3
-------
Design Development
3.2 Design Basis
3.2.1 Design Information
" , ; ;, ;"';ซ ป ]';;"' ,;ป,;, ป I:;;;:1: ซ, ' " ปซซ *|,ซ*| ' !' ,,'i,, ,;;; :*' ; |' , ":,"!' ;*"'';,/"! ;,; '' , " , ",;ซ, ;" 'ป I ปป
The basic information required to design a soil washing system is dis-
cussed in the following sections.
3.2T 1.1 Physlcarcharacteristics of the Soil
The first type of information required to design a soil washing system is a
quantitation of the soil's physical characteristics. The soil characteristics can
be readily assessed by performing a particle-size distribution analysis in
accordance with ASTM Method D422 (ASTM1963). This quantisation is
performed by a wet sieving technique to weigh the mass of soil sample re-
tained on each of 12 to 14 screens. The mass retained on each screen is
dried, weighed, and plotted to construct the particle-size distribution curve.
It is important to remember that results shown on this curve are on a dry
weight basis! Thus, the dry weight result must'lEie'adjusted wfien discus~sihg
field soil conditions.
The particle-size curve information yields the first process insights
for the engineer designing a treatment system. Three soil fractions are
generally separated or considered for treatment: the "oversize" fraction
consisting of particles with an average diameter >2 mm; the "sand" frac-
tion consisting of soil particles <2 mm but >0.074 mm ( 200 mesh), and
the "fines" fraction consisting of clays and silts with an average particle
size <0.074 mm (200 mesh).
' - i :" l : '
The particle-size distribution information is first used to determine the
mass of soil in each of the three specified fractions. This information en-
ables a first estimate of the size of unit operations to be used in the treatment
of each fraction and as an estimate of residuals that will be generated
through various treatment steps.
In general, the oversize material is the easiest to treat, the sand is moder-
ately difficult, and the fines are most difficult. This rule of thumb gives the
designer a sense of the degree of difficulty presented by the target soil and
enables a preliminary project cost estimate.
! ;i.ซi "'i " !! "' , Vis! ' ,'iniii.l
3.4
-------
Chapter 3
3,2.1.2 Contaminant Occurrence
The term contaminant occurrence is used to encompass both the form and
quantity of target contaminants in specific samples. Quantitation of con-
taminants in the soil matrix is easy. The soil retained on each sieve during
the particle-size distribution analysis is sent to a laboratory for chemical
analysis. The results of the laboratory quantitation are plotted on the par-
ticle-size curye to identify the contamination by fraction. This can be repre-
sented graphically using a bar chart as shown in Figure 3.1. This informa-
tion is very important to the soil washing system designer because it defines
which fractions require treatment and wliich fractions may not. This infor-
mation can also be presented in a tabular manner and expanded to show the
portion of the total contaminant load that exists in each fraction.
The form of the contaminants in each fraction is also very important since
it will suggest the treatment unit operation best suited to effect removal.
There are five forms that the contaminant (or contaminant mix) may take in
the soil:
Free. Examples of contaminiuits in this form include bullets at a
firing range or lead slag at a burn pit.
Particulate. Contaminants in this form include material existing
as free particulate within the sand fraction or paniculate that is
lightly bound to the surface of the sand. Lead is a good example
of a contaminant that can exist in either of these forms.
A Coating, m this form, the contaminant has covered the sand
particle. Polynuclear aromatic compounds (PNAs) from a coal
gasification process are a good example of this contaminant form.
Complexed or Bound. These are contaminants that have oxidized
in the field to form oxides, carbonates, or sulfates and are bound
into the dense matrix of the fines.
Soluble. Contaminants in this form have a relatively high solu-
bility and still exist in the soil matrix. While many elements/
molecules have a measured high solubility, it is often found that
the highly-soluble fractions migrate away from the site and into
the groundwater. Thus, it is relatively unusual to encounter this
form of contamination in ex-situ soil remedial applications.
3.5
-------
Design Development
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3.6
-------
Chapter 3
The form of the target contaminants can be identified by visual and mi-
croscopic techniques. The methods may be very simple or as sophisticated
as using color-enhanced scanning electron microscopy, but the identification
is very important in designing an efficient treatment system.
The form that the contaminants take in each of the process fractions leads
directly to concepts for treating each. For example, free material like slag
can be removed by mechanical screening. Separation of the sand and the
fines can prepare the soil matrix for more effective treatment. Particulate
material in the sand may be removed using the inherent density differences
in the contaminant and the sand, or by attritioning followed by froth flota-
tion. Complexed contaminants may be amenable to biodegradation if they
are organics or extraction/chelation techniques if they are heavy metals.
Soluble contaminants that still exist in the matrix can be treated in the pro-
cess recycle water with standard wastewater treatment techniques.
By determining contaminant occurrence, the remedial designer knows the
characteristics of the soil matrix that must be handled and the concentration,
form, and fraction in which the contaminants reside.
3.2.1.3 Level of Treatment
The level of treatment is a concept that is frequently misunderstood, misdi-
rected, or not discussed. The level of treatment refers to the extent to which the
soil matrix will be treated and what portion of the feed material will meet the
treatment standard. A soil washing system may provide simple treatment that
results in a fairly low volume reduction, or it may provide very complex treat-
ment and result in high volume reductions, The factors that determine which
approach to be used are cost and effectiveness for the specific site in question.
Four levels of treatment are commonly encountered.
Simple Separation. Simple separation systems may be appropriate when
the oversize and sand fractions already meet the treatment standards and
only the fines fraction does not. In this situation, a system might include
mechanical screening to remove the oversize fraction, separation of the sand
and fines, dewatering of the sand, and consolidation and dewatering of the
fines. The dewatered fines are then in a sludge cake form that can be dis-
posed at an appropriate off-site landfill. A simple separation schematic is
shown in Figure 3.2.
3.7
-------
' -it
Design Development
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Ol
-------
Chapter 3
Simple Separation Plus Sand Treatment. In this case, the oversize frac-
tion meets the treatment standards, but the sand and the fines fractions do
not. This situation encourages the designer to remove the oversize material
using mechanical screening and separate the sand and fines fraction for treat-
ment. Depending upon the form of the contaminants in the fines,
attritioning, density devices, and/or froth flotation may be selected. In this
case, the fines, exceeding the treatment standards, will be consolidated into a
sludge cake and disposed off-site. The sand and oversize meeting the treat-
ment standards remain on-site. A simple separation and sand treatment
schematic is shown in Figure 3.3.
Simple Separation Plus Sand Treatment and Fines Treatment. This
scenario involves a an uncontaminated oversize fraction and contaminated
sand and fines and for either liability or cost reasons, volume-reduction re-
quirements drive the treatment of the fines fraction. This level of treatment
is the most sophisticated and will generally include the approaches men-
tioned above in addition to bioslurry degradation of organics in the fines or
an extraction/chelation system for the removal of heavy metals. An example
of such a system is shown in Figure 3.4.
Special Cases (Oversize Problems). Although many "rules of thumb" can
be applied in soil washing, there are special! cases that must be evaluated on
the basis of the soil matrix/contaminant relationship. One special problem
that can be encountered is that the oversize material is contaminated. This
situation can arise if gravel is coated with a tar material, if there is slag about
the same size as the gravel, or in a particularly complicated situation such as
mobile contaminant (e.g., Cs-137) actually migrates into micro fractures in
the gravel or ion exchanges with natural cations occur, leaving a contami-
nated oversize. These special situations are difficult, but often can be re-
solved. The solution may involve crushing., grinding, jigging, and combined
processes. The use of such complicated approaches will be dictated by com-
parative cost considerations.
3.2.1.4 Site Conditions
The soil washing design must include the supporting infrastructure for the
plant, and for the materials handling that must be accomplished to excavate,
prescreen, and stage feed materials to the treatment unit. The site conditions
that must be considered for the treatment plant include the location of the
site, the layout of the plant and materials staging areas, the subsoil
3.9
-------
Design Development
0)
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Figure 3.4
Simple Separation plus Sand Treatment plus Fines Treatment
Fines
Gross
Oversize
Process
.V00-88
Overslze
r7
Clarification
.
Attrition
Scrubbing
Bioslurry
Reactors
Uewatenng Q
Hnes
Spiral
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. Clean Sand
o
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-------
in in ill 111
Design Development
111"! III III
ll I
conditions beneath the plant operating pad, the location and specifications of
commercial electrical power, the location and quality of process water, and the
weather conditions that may be expected during the period of remediation.
Evaluation of the site conditions is also important in determining the sequence
for excavation, the location of equipment for prescreening activities, and the
staging areas for feed soil and products.
3.2.1.5 Treatment Standards
The treatment standards for the contaminants of concern will deter-
mine the level of treatment and contaminant removal efficiencies that
must be attained. In many cases, the treatment standards will have been
established by the performance of a site-specific risk assessment. If so,
it is easy to use those values. In some cases, however, the risk assess-
ment may not have been completed or treatment standards may still be
under negotiation with the regulators. In those cases, it may be helpful
to use the Dutch B levels as a starting point (see Section 3.1.1), for in
many cases it has been found that these levels correlate very closely to
the end result of a site-specific risk assessment.
: - ?"lip1 i. j! " i'i'i.r, , i, "',"! p. ' i,r j; :,;,::"." :," ,'iij,1,! ^iu"'1,1 ,.:" , , ,"ซ,," 1JW
The work performance schedule will establish a reasonable range for the
System's throughput rate, which affects the size of equipment that is needed.
Project completion dates will be most important and will affect the labor
shifts necessary to operate the plant. Soil washing systems are very flexible
hi the sense that they are easy to shutdown and startup and, as such, allow
flexibility in working shift schedules.
3.2.2 Data Collection
i
The data required to design a soil washing system can come from
many sources.
3.2.2.1 Remedial Investigation Information
Remedial investigation (RI) reports will provide a tremendous amount of
information, but often not the specific information the designer may requires.
Nevertheless, the RI report should be reA'iewed in detail to learn the nature of
the operations that were conducted at the site, as this provides a good indication
. ' "' Jill'' '' i, l!, ' ,'' " ill 'I ' '''"1|11' '" "' ' "! "'''""
' " :' ';: : :; 3.12
-------
Chapters
of the form of contaminants that might be encountered. The report will present
the location and analytical results of all the soil samples collected during the
investigation. The soil samples may have been obtained through auger boring
and split-spoon samples, which are often not very helpful hi characterizing feed
material to a treatment unit, but they do give an indication of the nature and
extent of the soil contamination at the site. Frequently, particle-size distribution
analyses are not conducted during the RI and must be supplemented with addi-
tional sampling.
3.2.2.2 Site-Soil Sampling Program
To supplement the soil information from the RI and develop site-specific
information, an additional site-soil sampling program is required. After
spending (on average) more than $1 million on the RI, most clients or regu-
lators are often reluctant to conduct further characterization. Fortunately, the
needed sampling is relatively inexpensive (often costing <$ 10,000), and the
work can clearly be defined as part of the design effort.
The site-soil sampling program is intended to observe the physical condition
of the soil to be treated, identify other material that might be encountered (e.g.,
debris) and collect a representative sample of the soil to be treated.
For this activity, it is recommended that "test pits*' be installed. A test pit is
simply an excavation installed by a backhoe, one bucket wide and as long as
may be practical for the site. Material is removed during this excavation and
placed directly alongside the trench. The field engineer can observe the cross-
section of soil exposed by the trench and coUect soil samples from selected
areas. Similar test pits may be installed at other selected areas on the site. Soil
is recovered from these trenches and packaged for shipment. These soil
samples are then used for screening and treaitability study testing.
3.2.2.3 Treatability Studies
The treatability study is required for every soil washing project. How-
ever, the study, like soil washing itself, cam be modified to meet the specific
needs of the project being contemplated.
The first phase of a treatability study is often referred to as a "screening"
study and can be used as a "go/no go" test to determine whether it is useful
to pursue more detailed studies. This screening process consists of conduct-
ing a particle-size distribution analysis, analyzing the retained material for
3.13
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1 iii|"i|[' ; ,|'i'' liin Mi,, ,'' " ill, " , : ill IB i'i":ปi.:|"'"'i i, Hi,f:!'ป''" fV if f
Design Development
the target contaminants, observing the mode of the contaminants, and report-
ing the findings. The report may also contain a preliminary cost estimate
comparison to the other most likely remedial options that could be used at
me site and a determination on an order-of-magnitude level, whether soil
washing is technically feasible and economically competitive. This screen-
ing study can often be performed for $5,000 to $20,000.
A "full'* treatability study is also required on every soil washing
project. This study is a laboratory bench-scale evaluation of the process
On a batch basis. The study is essential to determine the process-flow
arrangement to be used; select physical separation parameters; define
process unit residence times; test chemistry, additives, and dosages; and
to confirm dewatering operations. The treatment units to be used are run
together in a simulated manner that will produce the clean products and
residuals. The study isi essential for the contractor to develop fixed pric-
ing and guarantee the results of treatment. Unfortunately, all treatability
studies are not identical. Because soil washing systems vary signifi-
cantly, each contractor will want somewhat different information and
may generate that information in different ways. This fact is often not
recognized, and contractors are given "standard" treatability study infor-
mation upon which they are expected to develop a bid. This weakens
the bid response because the contractors do not have the information
they really want, and a significant contingency gets built into the bid.
The treatability study will present the findings of the bench-scale work,
describe a process-flow arrangement, define operating parameters and de-
velop an implementation cost estimate. A full-scale treatability study can be
expected to cost from $10,000 to $50,000.
3.2.2.4 Pilot Studies
Treatability studies vary widely depending upon the particular level of treat-
ment, the complexity of the technology, and the experience of the contractor.
As a result, it may be necessary to conduct a pilot sEdy before full-scale imple-
mentation of a soil washing project is approved. A pilot study, for the purposes
Of this document, is a continuous-process test conducted in the field or at fixed
facilities, using all of the unit operations that are intended for use in the full-
scale" installation. "'Pilot' studies"are condlcteff'to colirirm"telll'treฃtoentlconcept
and to identify any problems related to "scaling up" trie unit operations previ-
ously assessed in the laboratory-scale treatability study.
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Chapter 3
i
The size of a pilot-scale study is not fixed by any existing protocol, but it
should be in some ratio to the size of the full-scale remediation. Pilot studies
for soil washing haye been performed using soil quantities from 91 to 18,144
tonne (100 to 20,006 ton). For average sites (those with about 27,216 tonne
[30,000 ton] of soil)|, performing a pilot study with approximately 907 tonne
(1,000 ton) is reasonable. Thus, if a pilot plant has a throughput capacity of
9 tonne/hr (10 ton/hr), the pilot study can lie conducted in one month of
actual processing time. This time estimate assumes only one shift per day,
five days per week. It also factors in the time required to collect samples at a
greater frequency than might be used during the full-scale operations. Pilot
studies have a muchj higher unit price per ton than full-scale projects and
may cost from $250iOOO to $750,000 total.
3.3 Design and Equipment Selection
3.3.1 Introduction
i
The actual design;of a process incorporating soil washing technology will
be determined by thd treatability study, the pilot study, and the philosophy
and experience of th? design team. No soil washing system is available "off
the shelf." The equipment selected to support the design requirements may
be specified by the designer, or it may come as a package provided by a
manufacturer or from a contractor who already has a soil washing plant
ready for use. If the system designers attempt to select each piece of equip-
ment for the plant, the design team will most likely confer with mining
equipment companies, for almost all of the required units are in common use
in the mining industry. Equipment that is commonly used in soil washing
systems is shown in Table 3.2.
1 ; ' -, . . .
3.3.2 Unit Sizing
Equipment for a soil washing system will be sized based upon the
nominal system throughput rate. The system throughput rate will be
determined by the mass of soil to be treated and the time allowed for
remediation. Commjon soil washing system throughput rates are 4.5, 9,
14, 18, and 23 tonne/hr (5, 10, 15, 20, and 25 ton/hr). In the United
3.15
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" ,'ป, is i I'fiir i
; miii'i,,1 !",!!llir,PPK i!j! 'i'i' .:1ll^l:l|1J|||||IVl^!l!"l^|1iilBrl ,"!.!'!'"ill1 ' ,. 'H Ilil il1"!!11"!'
inn i inn iln
Design Development
States and Europe, the most common rate seems to be
ton/hr) for a full-scale production unit.
23 tonne/hr (25
.,., ; ;,;;.:;:, Jgble,3,2
Common Soil Washing Equipment
(Major Soil Washing Components)
Prescreening Grizzlies and Trommels
Feed Hoppers
Conveyor Systems
Vibrating Wet Screens
, , ' i" !',:! hji1 i, iy*i." ' ill ';: ' i,:li',' i H
Pumping Systems
Hydrocyclones/Separators
Spiral Concentrators
Dense Media Separators
Attritioning Cells
Flotation Cells
' t -
Sand Dewatering Screens !
'!iif;. .iti !"!!!', ' !' i . '"' ;s'" 1i.i ill 'ซ ' ' :,/;.! """" - ; .'.' ' '"':<',>. "I'-.'M *-# * i:**.*/i'i'i:i.!e;i \XXM ifi" ,.i ;>:<.. :t Hi ;?, -i :-ซ
infiers jh
Acid Extraction Equipment ;
i ' '
Soil washing systems may be operated on very flexible schedules. They
may be shut down, left over the weekend, and started up again. It has been
r'-,,,:;,:.'., :; ::,.._; ., . , ;:..-; ;.;v found that one 10;hour shift per day, with maintenance performed on SaUir-
day, is me most convenient operational plan if the schedule permits. Soil
washing plants have been found to operate with an 80% or greater availabil-
ity rate or "up time"Of course, if necessary, the operational schedule can
be established on any required basis up to and including 24 hour a day op-
'::::::; :._: r :*: |;:~11:::" .' : :,::': erations, 7 days a week. ' '
'iinii i" i1: -I1"11:1!-:, i if. : <:*i , . ;, , ..' > .,; ., !;"ป:.;-, i, M.I ป. 'nmuM1., juiui isrii. i .it : ". if' i/nii ";;-' ซ -a LV > * 'ซป
Table 3.3 shows the quantities of soil that can be treated using a 23 tonne/
hr (25 ton/hr) plant. !
IIIM^^^ n IIIIIIM^^ liliiilM^^^^^^^ iliiiaiM^^^^^^ ari'ttii'l'..'!:!!.-;'.!!'! ii lhi3.iliLii.l,. 1' .Jlrl'lil iiiiUlii,.!:' liliillill^^^^^^^^ Hi!, ilk III iillliป iiJill^^ ;,l ill hill .
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Chapter 3
Table 3.3
Treatment Capacity of a 25 ton/hr Plant
Under Various Operating Schedules*
Operating Schedule
1 shift, 5 days per week
1 shift, 6 days per week
2 shifts, 5 days per week
2 shifts, 6 days per week
3 shifts, 5 days per week
3 shifts, 7 days per week
Soil Mass Treated per V/eek (ton)
1,000
1,200
2,000
2,400
2,400
3,360
Soil Mass Treated per Year (ton)
50,000
60,000
100,000
120,000
120,000
168,000
*10 hours per shift for 1 and 2 shift arrangements; 80% unit "up" time; 50 weeks per year.
3.4 Process Modification
A soil washing process is typically assembled from modular units de-
signed principally to maximize the segregation of contaminants from the
host soil matrix and secondarily to accommodate the local physical condi-
tions. Soil matrix attributes that affect design and/or operation may include
particle-size distribution, moisture content, and the degree and type of con-
tamination. Physical site conditions that may have an effect include ambient
temperature, proximity to buildings or sensitive populations, and local infra-
structure. Most of the potential problems posed by these variables can be
mitigated or eliminated entirely if considered in the planning stages and
resolved through treatability studies or accounted for in the system design.
This section discusses parameters that should be considered and offers pos-
sible solutions to potential problems. Many problems encountered in the
field are not readily resolved by any single approach. Site-specific treatabil-
ity testing, coupled with experienced field operations personnel, is essential
for the successful soil washing contractor.
3.17
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Design Development
I" ... ! .Ill; Mr'
3.4.1 Soil Matrix Characteristics
'i i .!'!.'! i, I " >':'' '.
3.4.1.1 Particle-Size Distribution
Soil washing relies on efficient separation of size fractions, typically, the
smaller particles contain more contamination on a weight basis, both be-
cause of their higher surface area and because clay particles have a greater
affinity for ionic species due to their chemistry and structure. If the soil
matrix includes a large fraction of fine material (i.e., if 20 to 30% of the
mass is <200 mesh), it may not be cost-effective to treat the site using soil
washing". Treatment costs should be carefully compared to potential cost
savings under other options.
If the site includes areas of widely variable particle-size distribution, it
may be necessary to stage and blend the feed before processing. If feed
batches vary substantially, different modules of the system may be over-
whelmed or underutilized, leading to continual process upsets such as
plugged lines, inadequate residence time in settling equipment, and poor
coltrol of chemical injection. Good site characterization and ample staging
area for feed material can allow blending of batches prior to loading in a
feed hopper. Balancing the loads on process modules will maximize operat-
ing efficiency and system availability.
If the particle-size distribution substantially differs from what was antici-
pated, or if it varies unavoidably when processing various site areas, process-
ing equipment can be physically modified or operated to compensate for this
condition within limits. tTpflow classifiers'arid mineral jigs can be operated
over a range of flow rates to vary the size of the carryover fraction. Some
hydrocyclone designs allow field modification to change the particle-size
cutoff point. Screens can be changed to substitute different mesh sizes.
Most of the'crianges available will allow partitioning at different size
cutoff points, but do not help much in modifying the capacity to handle a
particular size fraction. Rather than pushing the turndown ratio limits of the
modules, it may be necessary to use larger equipment, parallel units, or
longer operating times to iricfease'the'systern capacity without sacrificing
performance. This is why good feed preparation is essential to maintain
reliable steady-state operation.
> If ,'
3.18
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Chapter3
3.4.1.2 Contaminant Distribution
Most of the previous discussion regarding particle-size distribution ap-
plies to contaminant distribution as well. Certainly, for a process relying on
physical segregation alone, residual contamination levels in the clean-prod-
uct fractions will vary consistently with the degree of feed contamination if
the underlying soil matrix is consistent. A. process that solubilizes the con-
taminant may work most effectively on feeds within a prescribed concentra-
tion range, and more contaminated feeds may require additional stages of
treatment or longer residence time in some stages. In this type of operation,
feed blending may be driven primarily by contamination levels and second-
arily by leveling the particle-size loading.
If the contamination levels are extremely variable and "hot-spot" soils
make blending impractical, another option is phased operation, which entails
segregating the less-contaminated soils for initial processing, followed by
treatment of more-contaminated materials,, This type of processing requires
more planning, but reduces cross-contamination. The less-contaminated
soils can be processed at a relatively high throughput, and then the system
can be adjusted to process the more heavily contaminated soils more effi-
ciently. In any case, the same basic principles apply. Good site characteriza-
tion, staging the feed and blending or segregating, if necessary, will permit
the most reliable continuous operation.
3.4.1.3 Moisture Content
The moisture content of the feed may viiry dramatically in humid environ-
ments, in areas with shallow groundwater, or after precipitation. These may
alter the water balance in the soil washing process and may require compen-
sation. A natural increase in water content will reduce the need to add water
to reduce dust or disperse particles during processing. For a system operat-
ing with a net use of water, the natural water source may simply reduce the
demand on the utility water source. At some point, however, unrestricted
water incursion may make feed materials agglomerate or sticky, or create a
slurry too difficult to feed. Grading or contouring the site to control run-on
may be just as important as controlling runoff to uncontaminated areas.
3.19
-------
Design Development
"'!'! ' 'ป' , ซ' ''I!'
ic, < , ' ill:
Dewatering the residuals may also be complicated unless the filtering,
drying, and staging areas are protected from precipitation. Because disposal
costs are a function of weight, additional moisture content directly affects
: 11,1'1, '.Si 'iii'/iii.:;'1'1!!,!!!'"!"1'.,;''"""..!!!! ft1 ni ' I1:1''!:, .[lai1:1'';'!" :! ./'""'fi'1 }i", 'r 'J!1 " ," i 'S'iiffl .w1"!! Iti ifiJili!'jJlllr IliifLB,!1;.:!111 JW',!"1!!,!.' ;ป V *> a1 ' j*ปซif" ""jซ
project costs directly. Also, the waste-acceptance criteria for landhll dis-
posal restricts free liquids, thus necessitating reasonable control of moisture
content. If significant precipitation is expected at the site, the extra capital
Costs of operating under cover may be readily compensated by increased
operating availability regardless of the elements.
in iiiiiii i ii .flip it,,1 t , ., ,:M ifi'ii:',, ' " ,-", i",, ''i'".!. ' ' i",/11 , it1,1: 'I'll!1'"i ;.ซ ป" "! 'in ";< drwft; is rv
IN II II Ill III limit' l, ', .'i,,,,,, ' V ,,: I ||, Kn'HH ' || " ' .i'-i1; , '"'',, ,"' i if ,i S . .'! ! ' !l IN ,"' ,! : ill111
3.4.1.4 Clay and Natural Organics
1 : j
Soils with high clay content load the modules that separate fines. They
can also cause agglomeration and may be difficult to dewater. The first
problem is addressed above in the discussion of particle-size content. Here,
too, larger equipment or parallel units may be necessary to handle the addi-
tional fines load. Agglomeration canbe minimized by using enough water
to disperse the clay particles or by chemically modifying the water. In the
rough separation steps, including the bar-screen and trommel, large agglom-
erates may contain significant contamination, requiring hand sorting or wet
operation. Physically breaking up the large pieces of compacted clay is time
consuming and energy intensive. Finally, dewatering may require injection
'''' ::: "" !':;: "r' ::';; ;- "-': f_6f a flocculant to assist settling, followed by a filter press to squeeze the
'V i:';rw " ' fc,1 :;',,"'; VH ' '"'m,; Im '"ซ' water" ouf'ol1 void' spaces and compact the settled solids.
f"1 1'l '',} ,,,1,'i,!'!111 ' '' ' ILli'l '"! I'1 iK ,:,ii'"!,i' '" li'lPt 'tiniiillllll, i'''v!' . ' "''ซ 'lr i? VlCW' If!; <$ 'l|!;; , I ' , > i ",i; '. ,! ,", ?Xr , "!l,"', ,,,, I '''lili'llllPlP1,1! , "Wt "^ "Lll'l,"1 . lll'li:::i1 '!. '* ,"ป.ป"! ' 1 .r'l,"!! III"11!1*, I 'Ir111, mlllWI1" i'
^iiii I iiiininiMi' ' '!ฃ.! IL i;":ni i',,, !;,;;, JM! !" liii ' ' T.:? :+.; v^'i'11 a ''"?,.,"",;ป'' f ; . " n'V i"; ..,*-;, ',; "-i1 ,,t:,,',ii,, s,V,,:: "aji' " IRLii: '& rf:, I *i,iTJij'1 If *;:'* "i r . V'li'ii'ii:1 i'*.. : i'V. ซii,i a O'ii^'lA1
3.4.1.5 Oil and Grease
Small amounts of oil and grease can. be released with surfactants that
isolate the; organic molecules in micelles. Good mixing and adequate resi-
,,;:, 11, ,, fei^ ,, ^ y,,,,, ,,'S jj "j*ij^.| ^e^' time Jare essential to'facilitating suWac"tant"efTertiveness" Agitation
lr i "i'l-l [",{ "! It!, ( " ;; ',:', i'li' S'Jhl jil'1! nl'BK'Ui >ซ,:ilA, > iiiji!!1 Mil I! Ill l l i . v , _ . ,
may cause foaming, which can be controlled with a defoaming agent.
t t.'.
,"".:> -I',
may cause roaming, wnicn can oe comroiiea wiin a ueioanung agcxn. ocici
tion of additives can only be made through treatability studies. Slowdown
.... '!!i'u,' P1' ,nซ, 11 ' i , " , , ,|nj":, ,n wii, 'Pi",1' , 'H"" * *-* "
of a fraction of the circulating water for treatment will be required to main-
fain the wash water quality.
Greater amounts of hydrophobic contaminants may require pretreatment,
J, i |t' >j 'such'as a solvent extraction "or thermal desorption step7 pn'or to soil washing^
ir ;/'= , ; to remove enough of'the organic niatterto" affow processing" in'ati aqueous
I " 'If i ' I1' I" ' ; '"'; ''jji ' 'r'llji!"!' iri'liii1 li,1'",111 ' ',i,:i,i,;i,:iir"!ji"i"iiiiii'ii,:ii,,, " ii'tf ', ' ,'".,1,!, >,,.,!' ป' 'I'ri'niii:1,:!,'_ " '"nr. ,. '. ,.' ii" .ปi i guii i - s1 ;,:,," , ; ; i, , n,:",!,,,,
system. Weathered hydrocarbons may agglomerate soils requiring sizing
prior to pretreatment. A free organic phase may require an oil-water separa-
tor to allow the organic to be skimmed off for disposal.
3.20
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Chapters
3.4.1.6 Volatile Qrganic Compounds
The fate of volatile organic compounds (VOCs) must be decided in dis-
cussions with regulators prior to commencing work. Most of the VOCs will
be lost to the environment during soil handling if no steps are taken to cap-
ture them. Potential; exposure hazards to workers and the local population
must be considered in addition to the consequences of free release to the
atmosphere. Both Occupational Safety and Health Administration (OSHA)
and US EPA standards apply.
If the releases are to be controlled, open vessels may have to be covered
with ventilation hoods. Otherwise, the system can be operated in closed
vessels under a slight vacuum, or the entire process can be enclosed in a
controlled environment vented to a treatment system. The offgases and wa-
ter blowdown may require carbon adsorption. The carbon will require off-
site disposal or stripping followed by some type of organic destruction. Re-
moval of semivolatilp contaminants can be enhanced by vacuum operation
and heating of the process. Air monitoring equipment will probably be re-
quired to check the ambient conditions at the site to protect workers and to
ensure emissions are within prescribed limits.
3.4.1.7 Radioactive Contaminants
Radioactive contaminants may require the same type of controls on free-
release as described for VOCs. Radionuclides will either be gaseous (radon)
or nonvolatiles carried on dust or mist. Radon can only be vented, but radio-
actively contaminated particles can be controlled with high-efficiency par-
ticulate air (HEPA) filters. Primary and possibly even secondary filtration
may be required prior to venting gaseous emissions. Filtration and ion-
exchange may be used for water treatment. In addition, process residuals
must be disposed at Nuclear Regulatory Commission (NRC)-licensed sites.
If the residuals are both radioactive and hazardous under RCRA regulations,
they are considered mixed wastes and disposal options are very limited.
Wastes must meet land disposal restrictions and the NRC-licensed-waste
acceptance criteria for the disposal site.
! ' '
Treatment of radioactive contaminants will also require oversight by li-
censed health-physics technicians, and real-time monitoring of the effective-
ness of personnel decontamination. This is monitored at points of egress
from the soil washing process area using hand-held monitors to detect radio-
active contamination on personal protective equipment (PPE).
3.21
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Design Development
3.4.2 Physical Conditions
I: 'VX1 ' ป : l.l.t.'lBF i/ '.:i:'-'V, ill
;-j , ., ,; ;. i i.:t'j ;w ; a i,' "'a1';!
3.4.2.1 Temperature
Although both heat and cold can affect operation, compensating for low-
temperature extremes is more difficult. Heat will causejworker fatigue and
increased evaporative losses from the system. Heat stress is exacerbated by
PPE, but careful planning and limiting work shifts can ensure safe operation.
Evaporative losses from the process can be readily offset by adding makeup
water? Meat will'actually improve dewatering of the process residuals.
Cool conditions will assist workers wearing PPE, but near-freezing tem-
peratures will induce workers to dress warmly, which may again lead to heat
stress over prolonged work shifts in PPE. Freezing conditions can be ac-
commodated, within limits, by heating process solutions and heat-tracing
low-flow and small-diameter piping. Extended freezing conditions will
probably require a hiatus in operation, and cold-weather layup of equipment
including a comprehensive checkout to ensure thorough1 draining of the sys-
tem. Variations in temperature throughout the day must be considered in
planning two- or three-shift operations: Seasonal temperature changes are
largely taken for granted, but late or early freezes can fracture small vessels
and tubing and thicken reagents beyond use. These variations cannot be
prevented, but damage can be controlled by planning ahead and protecting
sensitive process areas. ]
i i i
'" " ' ' i i' in
3.4.2.2 Humidity ;
' i " ;;i!iJi *. ' T ,'ISiif :.(;;', !*:i:ซป. iil
High- and low-humidity environments create conditions similar to those
described for temperature extremes and soil moisture content. High humid-
ity will worsen heat stress, andacH'tothechallenges of, dewatering the pro-
cess residuals. Shortened operating shifts and more rest periods will address
^ -ซ^^.:jซ^i,^mg Smes ^OTtj^ng'^ help with the latter.
In addition, corrosion of instrumentation is an important consideration. It
may be necessary to move some field units to a controlled environment, such
as an air-conditioned control room.
'. _.. ,,,_,,_,,, ^ ,,,,,,_[,,,,_,,_, ,_,,,,,,,,,., . . ., , , ,, . | , ., |j I ; -:-
Low humidity wifi'^creaselfie impact of the above^oncerns, but can
make it more difficult to control the generation of hazardous dust. It may be
necessary to sprinkle excavation and staging areas with! water, and operate
all equipment accordingly in order to control exposure by inhalation and the
3.22
-------
Chapter 3
potential contamination of adjacent property. Inexpensive, biodegradable
water polymer emulsions have also been used to control dust by forming a
thin crust on the surface of piles set aside for longer-term storage (e.g.,
treated piles awaiting confirmation of analytical results). In radioactive envi-
ronments, dry air will also increase the static charge on polyester clothing
and make it more difficult to prevent personnel contamination. Natural-fiber
clothing will essentially eliminate the problem.
I
3.4.2.3 Grade
Most environmental restoration operations will be conducted on devel-
oped property. The operating area may only require compaction and instal-
lation of a liner to catch spills, or pouring a concrete pad prior to installing
process modules. Space must be available: for feed and product soil staging,
surge water capacity, and analytical support. If the area has not been graded,
however, additional planning is required to ensure safe and practical opera-
tion. Orientation of support functions, ingress and egress paths, and the
utility interface should be functionally designed for efficient operation and
movement of materials.
Soil contouring may be required to create surge capacity for process water.
A gentle slope can be exploited by discharging the process water blqwdown to a
small-lined settling basin that cascades to lined secondary or tertiary basins
from which the clarified water can be pumped for additional water treatment
and process makeup. Similarly, some grade can be exploited for a gravity-flow
process in which pumping and level control are minimized by designing se-
quential process steps in a cascade fashion. Flow between steps is by overflow
or syphon. Approximately 929.4 m2 (10,000 ft2) of space is required for a full-
scale soil washing plant working area.
3.4.2.4 Debris
As of this writing, federal environmental regulations consider materials
greater than 60 mm (about 2 3/8 in.) to be debris and subject to different
treatment standards for hazardous constituents than smaller materials. The
debris classification includes natural materials such as rocks and branches as
well as man-made construction materials and trash. A pile of material may
fall under this classification if it is judged to be primarily debris by visual
observation, even if it is not composed entirely of debris. Legal guidance
should be obtained and local or state regulations on pertinent federal
3.23
-------
"ion;:!",1 ' it i,i< ; is',
'iiirt i "!",. : :;;::!, -ss;;;-.:. Design Development
. regulations checked [see the Code of Federal Regulations (CFR) at 40 CFR
268.2(g) and 268.45] to ensure proper compliance.
. : : I , ' " '"'"
The regulations prescribe how debris can be treated and disposed. Fur-
ther guidance has been published commercially (e.g., Elsevier Science, Inc.
1996, updated annually). Whether debris should be treated, recycled, or
disposed as nonhazardous solid wastes, or sent to a hazardous waste landfill
can only be determined by a cost analysis and discussion with the respon-
sible regulators.
Debris should be removed from feed materials npt only because of these
different standards, but because large, irregularly-shaped objects are prob-
lematic in operation and may damage processing equipment. Separation
from the soil matrix is typically done using a bar-screen or grizzly-type sepa-
rator and a rotating screen (trommel). However, because of the extreme
variety in debris and the history of each site, a tailored approach may be
required, including flotation, mineral jigs, and possibly labor-intensive
manual sorting.
f i,!;^,, !,. ;, I I II Illllll II II II II I I I I II ' ;; 'llij I
Special cases also extend to munitions, batteries, and metal fragments.
While these materials may be too small to be considered debris, they repre-
sent a pure contaminant source that may increase the residual contamination
s. 'II "I, to ^acceptable levels for any'sample'in wffic'h'the'y' are included, g^^.^
may be affected by exploiting density or magnetic differences between the
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metals and the soil matrix. Successiof the operation may rest on efficient
physical separation. Costs may potentially be offset by recycling the metal
fraction at a commercial smeiter, thus, avoiding the costs of disposal.
3.4.2.5 Vegetation
Vegetation should be removed as debris to the extent possible. Small
plants, grasses, and roots will blind screens and filters and float in clarifying
equipment. Large amounts of small vegetable matter may require a separate
flotation step to allow removal by skimming prior to screening sands and
small gravel. Some plants have a substantial affinity for metals and may
concentrate contaminants in their tissues. Disposition of this material should
be determined m discussions with regulators. Staging of the vegetable mat-
ter for separate off-site treatment and disposal may be advantageous.
3.24
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Chapter 3
3.4.2.6 Animals
Indigenous species will probably not affect operations significantly, how-
ever, protected species may require fencing or other barriers to limit access
to contaminated process water and electrical equipment. Again, this is a
matter to be resolved with cognizant regulators and through use of best man-
agement practices.
3.4.2.7 Sensitive Populations
Proximity to sensitive populations such as schools, day-care facilities, and
hospitals does not present additional constraints, but may exacerbate some of
those already described. Certainly, air and water emissions and site access
will be more carefully controlled to reduce any potential health and safety
risks. Adherence to OSHA, US EPA, and local regulations is, of course,
mandatory, but good communication and community relations are essential
to maintaining local cooperation and meeting the project schedule. Similar
consideration should be given to any population, structure, or protected area,
such as watersheds or wetlands that may be perceived to be at risk.
3.4.2.8 Infrastructure
Any supporting resources required for operation must be secured prior to
commencing operations. Utility power can be supplemented by generators,
but water may have to be trucked in if there are no continuous local sources.
Relying on irrigation sources or stream flow will be subject to water rights
and may lead to intermittent availability in some areas. Recycling water to
the extent possible will reduce supply and disposal costs and minimize the
impact of aqueous discharges. Discharge to a local publicly owned treat-
ment works (POTW) may reduce treatment costs and enhance local commu-
nity relations. Access to roads may be restricted by size and weight limita-
tions. A route for ingress and egress of heavy equipment and waste ship-
ments should be negotiated with local authorities.
3.25
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Design Development
K
3.5 Pretreatment Processes
A soil washing process is intrinsically a modular system tailored to site-
specific conditions. As such, the configuration may vary widely from one
application to another. In addition, some systems rely solely on physical
segregation of highly contaminated fine material from less contaminated
sand and gravel fractions, in contrast to extractive systems that use chemical
additiyes to solubilize contaminants. The entire physical separation process
could be considered pretreatment for an extractive system that actually dis-
solves contamination out of the soil matrix. For discussion here, pretreat-
ment steps will be considered to include the materials handling and condi-
tioning operations necessary to segregate the four principal fractions: debris,
gravel, sand, and fines.
Site preparation, including characterization, grading, control of run-on
and runpjf, securing utilities, community relations, and system installation
*:anci^ shalce-3own,'are all essential activities, but are not discussed here.
^reK^nejgitpp'eraSpns are discussed sequentially in the order they would be
expected to appear in a typic'arproceiss^sterli^^ of debris and
vegetation, continuing with feed staging and blending, rough separation of
gravel, and efficient segregation of fines from sands. Each section concludes
with a short discussion of follow-on treatment for the subject fraction.
'MB
3.5.1 Debris and Vegetation Removal
ill
il ' l1'!!'!1 Hi
3.5.1.1 Bar Screen Separation
Debris and vegetation are described in Sections 3.4.2.4 and 3.4.2.5, re-
spectively. In general, debris is any material greater than 60 mm (2 3/8 in.)
in at least one dimension [see 40 CFR 248.2(g) for a more exact definition].
Debris should be removed because it must meet different treatment standards
than other hazardous wastes and because it will interfere with downstream
processing equipment. Vegetation should also be treated separately because it
will blind filters and sc^reegSj interfere witih(sejtlmg and flotation steps, and may
contain substantial contamination concentrated by plant metabolic processes.
,, I
Most debris can be separated simply by dumping the gross excavated
material on a bar screen with the bars appropriately spaced (see Figure 3.5).
,,. <; in,:, . i;:iiiiiii> si, ซ, tsi: nun iimi! ; ',:!iti: i
"v,: :-.; v: :. .-.;. 3.26
i IT ti;faiu.insi;-:ILIIIM^ f iiM;;
j.-k^
-------
Chapter 3
Regulations allow reasonably imperfect segregation, as long as the debris is
primarily greater than 60 mm by visual inspection. If the material contains a
substantial amount of woody vegetation and medium-to-large plants, they
should also be separated in this operation. The oversized product will prob-
ably pass cleanup criteria without additional treatment because of the low
surface-area-to-weight ratio. This may not be true if containers are present
with residual contamination inside, if large clay or precipitated metal con-
glomerates are carried over, or if fragments of regulated metals are in the
matrix. Additional characterization may be required to demonstrate this
fraction is clean enough for disposal. Depending on the site-specific condi-
tions, manual sorting and/or debris treatment meeting regulatory require-
ments (40 CFR 268.45) may be necessary.
Figure 3.5
Debris Being Separated by Dumping Gross Excavated Material
on a Bar Screen with the Bars Appropriately Spaced
3.27
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Design Development
3.5.1.2 Rotating Screen Separation
An inclined rotating screen (trommel) may be used to provide additional
rough separation (Figure 3.6). The tumbling action of the trommel will also
assist in breaking up agglomerates aricl"stripping compacted soil from
cobbles and gravel. The trommel may be operated with or without internal
water sprays. Dry operation reduces caking in the trommel, but water sprays
reduce dust and enhance the comminution effects of the tumbling.
Figure 3.6
Trommel
3.28
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Chapter 3
Small plants, grasses, and some slender debris will carry through the bar
screen and, if not separated, will interfere with downstream processes and
may damage equipment. A trommel can perform more than one size separa-
tion, and if site conditions warrant, the bar screen could be set to remove
only very large material (3 to 4 in.) and the trommel used to remove the rest
of the debris as well as a smaller size fraction. Upflow water separation
columns can be effective in removing small pieces of vegetation and fine
humus or humatic organic matter. If gross amounts of plant matter carry
through from the debris separation, a second cut with the trommel to yield a
+3/8 in. (+4 mesh) gravel fraction would catch most of the vegetation. If
necessary, the grassy matter could be floated out of the gravel fraction for
separate disposal. The +3/8 in. (+4 mesh) fraction will likely pass cleanup
criteria with only limited treatment (water rinsing) or no further processing
at all. After sampling to verify allowable residual contamination levels, the
gravel could be returned to the excavation.
Cutting out the large gravel fraction alt about 3/8 in. enhances downstream
cleaning operations, which are only effective on particles up to approxi-
mately that size. For example, an attrition scrubber uses opposed impellers
to intensively mix a soil slurry, causing the particles to collide and abrade
surface contamination. Particles greater than about 3/8 in. are simply too
heavy for an aqueous solution to keep suspended, and they settle out, reduc-
ing the overall effectiveness of treatment,
3.5.2 Feed Preparation
Steady-state operation allows the process to run most efficiently for the
longest period of time. .This translates directly to cost-effectiveness and
building confidence in the eyes of regulatory authorities. A soil washing
system is only as good as its designers can make it based on their experience
and the site-specific information they are provided. Good treatability studies
and field/fixed-facility pilot studies can provide the needed information and
often pay for themselves in better designs and reliable full-scale operations.
Good operators can make up for some operating excursions, but operating a
system under conditions outside the scope of design will still probably be
reflected in the final results. Good feed preparation and feed soil blending
are often essential to keep the process within its reliable operations bound-
aries or "operating envelope."
3.29
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DesignDevelopment
11'';' i! ,I * . iil':' :,:: 1;:;' if" > "M "f".": f',ซ i;:,'i; *;,:, ,::"!"< :.*ved'SW-8'46''iiaซthbds(US'EM'r986)VN^
performed using a five-point grab sample composite for every 100 tons
processed.
Ample space should be allowed.to hold feed batches for characterization
and blending prior to processing. With debris and large gravel removed,
representative sampling and homogenization are simplified. As the job pro-
ceeds, the time and care invested in feed preparation can be adjusted to fit
operational needs for cost-effective processing.
3.5.3 Gravel Separation
Site-specific conditions dictate whether additional gravel separation and/
or cleaning is warranted. Vibrating screens may be used to segregate gravels
from the "sand and silt/clay fractions and remove most of the remaining or-
ganic debris, such as leaves and grasses. Again, pressurized water sprays
can be directed at the screen deck to enhance cleaning of the gravel and
wash sand and fines through the screen. Inclined screws can also be used to
perform this separation.
3.30
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Chapter 3
At munitions sites, a significant amount of metal may be contained in the
gravel as both metal fragments and partially oxidized deposits smeared on
particle surfaces during impact. A mineral jig, which is a type of upflow
classifier, may be used to separate metal fragments as the more dense under-
flow. A jig also abrades soil particles in an agitated bed of metal or ceramic
balls. Additional cleaning may be accomplished by adding an extractant and
taking advantage of the good mixing in the jig to solubilize metal deposits.
However, treatability studies are necessary to determine whether the extrac-
tion is cost-effective in the presence of a free metal fraction. It may be more
effective to separate the metal fragments with water to minimize dissolution.
If the gravel fraction requires additional cleaning to meet disposal criteria,
treatability studies should be used to design a cost-effective extraction
scheme to reduce the residual contamination.
i '
3.5.4 Separation of Fines from Sands
In many cases, the sand fraction will require only modest treatment, if
any. The fine silt and clay fractions may be the only material contaminated
beyond release limits, and, if the sands are rinsed free of fines, it may be
possible to release them after verification sampling. If cleaning of sand is
necessary, attrition scrubbing can be used for particles as small as 200 mesh
(75 pm). Below this size, the momentum of the particles is not sufficient to
cause significant surface abrasion in an aqueous solution. Whether or not
the sand fraction must be scrubbed, thorough separation of sand from finer
material is key to the success of the process. Carryover of a small fraction of
highly contaminated fines can cause the relatively clean sand fraction to fail
verification testing.
Rough separation can be achieved with an inclined screw to provide ini-
tial sizing between gravels, sands, and fines. The classification obtained will
reduce the load, but secondary separation will probably still be required to
provide a clean sand fraction.
Hydrocyclones can efficiently perform this separation. Some cyclone de-
signs allow reconfiguration hi the field if the initial design requires modification
to adapt to field conditions. A hydrocyclone operates in a fashion identically to
the cyclones used for separating dust and grains from gaseous streams, except
the motive fluid is water. Particles are separated by their relative drag as the
rotational flow of a slurry imparts centrifugal force. The slurry enters the cy-
clone tangentially, and larger particles are forced to the vessel walls to exit the
3,31
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"
DesignDevelopment
bottom while finer particles exit the top of the cyclone. Separations of over
jg-jjk jn agjngie p^ and banks of hydrocyclones can
"it'it'- in, up!1' :;S.H
,":m it"!!"1
l?| bperateci in series to attain a desired efficiency.
"Ii' ?t$:'3&'$ฃ!' ijirill":':;; ffjll!iii;*&'l I1 HI i, 'i"1 IliS '.'fWS'rfi'i'^.'dllSENKiy^j , ,
Nearly absolute separation can also be achieved using an upflow wa-
ter column classifier. Particles are once'again ggparate^ by their differ-
ences in density and relative drag, this time manifested in settling rates.
rry is pumped into a column of rising water. Those particles
pelting moire rapidly "than the' buTJcfiow exit" tEe Bottom, arid finer par-
''""" 'tides"are 'eluted'wffi'the"water to exit~th"e topi." TEe particle-size cut is
adjusted bysimply varying'ithe "water" flow rate".
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3.6 Posttreatment Processes
Posttreitment processes will vary depending on the configuration re-
quired for the specific application. For the purposes of this discussion, it is
assumed that all planned soil decontamination has been accomplished, and
, ..... ii ""I I'li'lUII'!' J HIIIK ...... ' ........... HI' ' "J! ....... I":'" ......... 1'" ' ...... I ..... ................ - ....... ,11 'll,'" ..... ' ..................... ' ........ , ............. J ........ ป"!. ..... Hi ' :"ซ''"'> .............. /'"I 'S ............. 9 ....................... ' ......... ซ ..... ' .......... " .......... ..... J ......... .............. ' ...... ' .......... ..... '''" "ป ................ ' ...... ....... ' ............... ' ......... ..... ป ............. Ji ........ '
propnetary solvents are not considered. All that remains are the treatment of
gaseous and aqueous effluents and the preparation of process residuals for
disposal. All requirements should be negotiated witii authorities and com-
municated to the public prior to commencing operations.
[[[ ..... l ..... .......... ...... i [[[ ; ...... ........
............ ............. , ................. .................. ............... , ..... , , ................... .................. .. ...... , , , ........................ , .................... , ........... ......... ..... j ................. ..... ........ ........... .......... ..... , .. .......
3.6.1 Gaseous Emissions
1 " ' "'' '" '
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"
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' "I1 VII!1!!ซ' ,i,' ''"'ilHPII
Most soil washing applications are intended* for treatment of surficial soils
exposed to the atmosphere. Most, if not all, volatile contaminants have been
lost. If the process solutions are primarily water, possibly with some pH
adjustment and some flocculant added, the capture and treatment of gases
will probably not be required. Atmospheric controls may be limited to miti-
gating' .fugitive' dust during 'excavation""anS'materials Handling''3ufiri"g'"5eed
preparation.
If significant amounts of VOCs or radionuclides are present, however,
offgas control and treatment will probably be required. Controlled ventila-
tion, activated carbon adsorption, and high-efficiency paniculate air (HEPA)
filtration arediscus'sed'm'STOtibns'^^.l^S'ia^sXl.'V.
Tt,,':,,,.1"!'. , -I 5"if,.;,,'
, Ml',"",,'1'.!,!"!, ! H hi
i'iiiil!:;'!,
-------
Chapter 3
3.6.2 Water Treatment
Ideally, the soil washing process is run as a net user of water because the
product soil fractions contain more water after processing than they con-
tained as feed. If this is possible, only the water contained in the pro-
cess at job completion may require treatment. If this is not possible, or
if a blowdown stream is required to maintain water quality or chemical
effectiveness, then a water treatment system will be required. The sim-
plest form of treatment can be accomplished using a quiescent settling
pond to clarify water for reuse or discharge. The site can be contoured
and a liner used to create such a pond. Clarified water can overflow or
be syphoned to another pond for reuse or sampled prior to discharge.
Ideally, the clarified effluent can be discharged to a local POTW and
must only meet local sanitary standards.
If contamination is significantly solubilized and the local POTW cannot
accept effluent after clarification, or if the discharge must be to an open body
of water where more stringent requirements apply, more sophisticated treat-
ment may be required. Suspended solids can be reduced further using sand
or multimedia filters. A free organic phase should be skimmed using an oil-
water separator, and dissolved organics free of fines can be adsorbed using
activated carbon. The spent carbon will require off-site disposal or stripping
followed by some type of organic destruction. Metals and radionuclides can
be removed using some combination of precipitation and filtration or ion
exchange. Careful pH control can minimize the amount of sludge generated
and facilitate settling and filtration. Many selective ion-exchange resins are
available to focus on specific ions rather than depleting exchange capacity
on the salts typically found in natural waters or leached out of the soils dur-
ing processing.
Treatability studies may be required to ensure that fairly standard water
treatment practices will be effective under site-specific water chemical char-
acteristics, particularly if the process used chemical additives that may inter-
fere with coagulation or ion exchange. Simple jar tests can be used to deter-
mine initial feed rates. Pilot testing is used to refine feed rates to ensure
reliable, effective treatment.
3.33
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iiiiiii ill ill in ill i nil nil 1 ill i nil i iiiiiiiiiiiiiii iiiiiiiii|iiiiiiiii in ill
Design Development
ซ'(ซ ': jii!:':: :!ซ;';":" ' j'1':ซ ซ* -! ป'3.6.3 Dewaferinci Fines
'III "li1 ' III,,',,!! ' ,' 'in , ,! 'i. J ป'" , liliUlllj,
I, ''HI,, ; 1 "In' ' li 111 ' i' ih i!;"''!,!;, "n, "" 'UllliJIPII'li IIIMW
In many cases, soil washing is limited to separation of contaminated fines
from the rest of the relatively clean soil matrix. In some cases, the
contaminant(s) can be extracted from the fines, but there are always some
residual fine materials left from processing. Dewatering the residuals can be
the "Achilles heel" of the process.
Clay particles are very small, and the n eg alive surface charge on the par-
ticles repels like particles, so they do not settle even after extended periods.
Flocculants are long organic molecules with many charged sites along the
chain that can stabilize surface charges and allow the molecules to bridge
between particles. Small amounts of flocculant can sometimes greatly assist
settling and clarification. The settled slurry can then be pumped to a filter
press, which forces water out of the slurry to create a sludge for disposal.
Plate and frame presses may be used, but are limited to batch operation. A
continuous-belt press is better to support continuous operation. Centrifuges
are another pos'siblie'Hewafering 'device, but care is requirecl in design/testing
to ensure that the required performance can be obtained.
I i I ..... ', ..... .......... ......... ."" ...... : ..... , ...... ",: ,:!":, ............ '.
For processes that solubilize metallic contaminants, similar dewatering is
necessary following precipitation of the metal by pH adjustment. Dewater-
ing can also take place in stages, depending on site-specific project needs,
with a press or centrifuge doing the bulk of the job followed by "polishing"
dewatering conducted with solar, surcharging, or electroosmosis techniques.
The added dewatering cost can often offset high disposal cost.
3.6.4 Disposal
The waste-acceptance criteria for the ultimate disposal of residuals will
dictate additional requirements for stabilization, analyses, and packaging.
Landfills cannot accept shipments containing free liquids, so it would be
wise to place dewatered residuals under cover to preclude exposure to rain or
snow. Ample space should be available to continue processing even if ship-
ment is delayed because of analytical or transportation difficulties. In arid
environments, it may be advantageous to enhance contact between the slud-
ges and the ambient air to further reduce the water content and, therefore, the
weight of material to be shipped. This can be accomplished by turning the
pile or spreading it if space permits.
3.34
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Chapter 3
Leachable metals in water treatment sludges or soil fines may require
stabilization prior to disposal. A variety of methods based on pH adjust-
ment, sulfides, and pozzolanic additives are available. Treatment may also
be available from the disposal unit operator, or on-site services can be pur-
chased from commercial vendors.
Organic material, such as contaminated humic matter or loaded activated
carbon, may be incinerated, stabilized, or directly disposed at a landfill,
depending on its characteristics after treatment and the relevant waste-accep-
tance criteria.
Disposal of radioactive residuals is discussed in Section 3.4.1.7.
3.6.5 Equipment Decontamination
Decontamination of process equipment is necessary before removing it
from the remediated site. For typical organic and RCRA-regulated metal
contaminants, this may only require flushing the process lines and rinsing
the equipment with fresh water. Rinse water can be treated with residual
process water, which will also serve to flush out the water treatment process.
This requirement becomes much more restrictive when processing radio-
active materials. State-of-the-art field measurement of radionuclides is at the
picocurie level, which, for short half-life nuclides, translates to several or-
ders of magnitude below detection limits for chemical species. Process lines
nominally smaller than 2 in., small pumps, filters, and ion-exchange media
will probably be disposed as wastes. Decontamination of process equipment
may require aggressive solutions that will quickly corrode carbon steel. In
addition, it is common practice for health-physics technicians who are re-
sponsible for preventing the spread of contamination to automatically con-
sider contaminated any surfaces that they cannot access to monitor.
Decontamination requirements for transporting equipment from a con-
taminated site must be negotiated prior to deployment. Finally, it is also
advisable to negotiate valuation and disposition of equipment that cannot be
decontaminated prior to accepting a restoration contract in a radioactively
contaminated zone.
3.35
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ii ii i1 i' n i in i iiiiiiiiiiiii iiiiiiiiii
Design Development
3.7 Telemetry, Process Control, and Data
Acquisition
: ' i .1 ITU i '; ./Hi, ii 'iiiiiiiiii:' ,1 ;n:,n r", i, n,yiiii
SST^iซ 'i " / r;,:,, ซ :; ;i"; =;=":," ^; Equipment used for data acquisition, process 'control, and telemetry have
i^ 'ii" . ifpi'i'J'if Ii ^'ipl'p ill;,i^^been greafly improved' and diversified, making it possible to constantly
Illlllillllliillfll '"!,,, iillll! '1118ill "'.lihiii'fnhi!1 '!!ป 'lilii!1!',!," ''.liliiLlilllliiiiiiiii'i'l'iii'liliiill ,: ,i. '1'i'ii', C"'1111! illK" riiliiiiiimiliillll'r "liilllil!1"! llni ''"inifci'Sllliiiiillflii"11!. m\V": H'"M\" x\n,'m *.*.tm i ^mmmM "i ,j ii "ii,, ' , , 'i!ซN#r ii ,ซ, "''in'" '=ป'' a ซs yep
~^^m^ ,,; ;;;:.; :; n;,r;^ ;,;ป ^:;;;;;,,;;; '',,,"' monitor and control most types of feed streams and many variables (e.g., pH,
SSP!iiSiflT'J& etc"). Such" equipmeHcan'rmprove the Opefation o f
ฃHi''lftti':^!!fi' ",,;!'iซ^ 'ifi':iy:;: งQil washing units and reduce costs. This section" discusses tfie gen"e"fifs o"f
iiimi.*: liBiiip-iiii ป,l.Mmi4.:w i ;ซป:' ii' * ,ป.this technology, its potential applications, specific types of meters and telem-
IK i iiii&WKiw^ji' 'itiS1'; ,|jg js not intenSeS to be an exhaustive
^f-:EE: I ,,,,;;;: ::;:;:.fE' rjEj::,;,' ,, discussion of meters and aprjlicatipns relevant to soil washing. The purpose
;;jii;; ^ w ;;j; [ f^ ;;;" '; ; is. only to provide examples of instruments and stream types that have been
| ;;;:,;, ^^ :::':,, ,::::' ;::z;,;::"::,,,nionit:ored in past projects.
"~: "J;;::,:.::1 ^ :^,:,;.,:: "'3.7. f Jenefitsn ijf ^ ,(^, f ' , ' f ^| ^ t :i i ,_ , _ i( v^
ui if , t '! ' :''.ปf;!i(*i.iซrB?'BB i"*" liiiH V-':,i(i "''ปAutomatic data acquisition, proC"eJSs control, arid telemetry techniques
SSSSf.A^ ' SlS^.lfffii: 'liil*!ill 'i|f:l'have many benefits for soil wasning op'ergfiohs. Automation can cut labor
;=^":= J: ::'j^: J::^';.' ;''=;' ]= costs by reducing manual monitoring and sampling. Soil washing results
' ;ii" "* '" ' '*' '" " ;s '" ''" ''" may improve because constant, real-time control is possible, allowing opera-
'"'TinT";'; ^'.rj^^m! ~ " " tors to know immediately when a stream's characteristics fall outside the ^ "^
required operating parameters. Constant feeds can be achieved and moni-
": :.rii ' ~ i"::;: ::,'-.' iป \^^''.-'^'' ^ tored, which is a necessiity'for optimal operation of most soil washing equip-
ment. Finally, data are more accurate when recorded automatically. These
techniques reduce the amount of manual dictation required and improve the
'" / "; ฅI{i$ i;f i *j|?v' i,|i^'iM w'fifj^uericy'or' data" collection.
Sii IK i 'i::i,iiiiiiii"' l!::t:i|m;,:il I,:' ;:i::iil,li , ii llllilllll , I'1'")'1 'III .,
parameters that can be measured are pH, flow rates (for liquids, solids, and
some sludges), totalized flows, temperature, pressure, density, and sump
levels. In addition to performing data acquisition functions, the equipment
in i'
1 il HI1 ni"
3,36
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Chapter 3
can be configured within process loops for automatic control, automatic
sampling, and alarms. Telemetry systems can be used in any application
provided there is a means for sending the information (e.g., radio, telephone,
or broad-band cable television).
Certain conditions may affect the accuracy of telemetry equipment and
hamper its use in a soil washing operation. Examples include high-range or
high-plasticity solids, low flow rates with high solids content, pulsating
feeds, or pipes that do not run full at all times. Telemetry accuracy may also
be affected if meters are placed on equipment that vibrates severely or is
very sensitive to head or volumetric displacement.
3.7.3 Meter Type
3.C3.1 Conveyer Load Cells
Conveyer load cells can be effective for measuring high-solid streams.
They are installed into existing equipment and can replace additional materi-
als-handling steps, such as weighing solids before they are fed to the soil
wash unit. These cells vary by design and capability, but generally consist of
electronically balanced load cells, which provide a weight signal by measur-
ing vertical forces of mass transmitted. The cells are supported by a con-
veyor, which has a speed sensor. When the speed and weight reading are
combined, the flow rate and amount of totalized materials can be integrated.
The size of the load cells varies with the size of the conveyer. Several
options and measurement designs are available, depending on the applica-
tion. Process-control loops can also be installed to make feed rates more
constant.
3.7.3.2 Digital Doppler Meters
Digital doppler flow meters are recommended for liquid streams that
contain fine mineral matter or have low solids content. These meters work
with sound waves or magnetic flux to measure flow rates through pipes and
are designed to measure aerated and/or solids-bearing fluids. Since the
doppler meters clamp to the outside of the pipe, they are nonintrusive, pre-
venting contamination and leaks. For this reason, these instruments are
effective for use with corrosives and petroleum products. The operating
parameters to be measured and the processes to be controlled by these
3.37
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II I I
Design Development
metersvary and are determined by the user. Some units have the capability
to discriminate and reject noise frequencies and power-line harmonics.
3.7.3.3 "Venturi" or Differential-Pressure Transmitters
iitii
;. F:II': ..'iii
Differential-pressure transmitters read the change in pressure across an
orifice or a narrow throat that, in turn, is related to the flow rate of the
stream. This can be used to measure flow rate, level, low gage pressure,
vacuum, and specific gravity. The amount of volumetric displacement moni-
tored by these instalments depends on a particular unit's design. The range
of pressure change, output signal, material of construction, and other options
depend on user needs.
3.7.3.4 pH Meters
For proress-con&rapp^ meters' require a sensor
and analyzer co7itr6Wen TEe" analyzer portion can be used for on/off relay
control an'a p^brtibrial"control capability. Analyzers are available to pro-
vide a pH signal as a voltage or an amperage, as required. The pH sensors
either read pH directly or measure it differentially with respect to a solution-
ground electrode. Materials of construction, measurement signals, mounting
requirements, ^diemp^raturesensors can be adjusted based on needs.
3.7.3.5 Temperature and Pressure Meters
Temperature and pressure meters are quite common and readily available.
.":!:,. :;= loops by using a
";ii',;:,ii;'"jSgliior and anaiyzer controller unit. Many different styles are available to
accommodate most user needs.
! jail,," li IK
:::: 3.7.4 "Costs
|!i>nr;! F>
' '" tU lil
j'11!! ij u i
1 f tt; ' '!' !"! J'l *
||if!|Si';, f -s{'!,; u i" "!-:|||||iii iiijii ',: ,|i:,( ,, t-fiff ,"-'M,'"* if! i ';'Ti.i'" ill lilllll . illlli . ,ii " I! i"" ,;"ซ",. MS;1: 'I'll .Ill 5 IIIIRI i * *(!.: Ill N I: .HI! tiBiLSi;!!'! lli,-||K:ซ- ! ,',
-------
Chapter 3
The estimated design and equipment cost for a telemetry system to per-
form automatic data acquisition for a soil washing plant that processes 1 to 5
feed streams at process rates of 1 to 10 tonne/hr (1 to 11 ton/hr) ranges be-
tween $40,000 and $80,000. The addition of complex devices, such as den-
sity meters or process-control loops that completely control the soil washing
system, can increase the cost by amounts ranging from $250,000 to over
$500,000. Special materials of construction, elaborate telemetry systems, or
unusual instrument functions will significantly affect these cost ranges.
3.8 Safety Requirements
3.8.1 General Considerations
Safety during the soil washing operations is essential to protect on-site
and off-site workers and the public from the associated hazards and pollut-
ants. This is accomplished by site safety and environmental control plans.
The environmental control plan is a separate document which is linked to the
operating permits and is addressed elsewhere. The site Safety Plan is a de-
tailed operational document defining how workers and site visitors will be
protected. It should contain all the information and response data required
for the worker, including such items as the location of hospitals, types of
wastes to be handled, recommended levels of safety equipment, and emer-
gency procedures and contacts for the site. The Safety Plan must be made
available to all workers at the site, and the workers must be given an oppor-
tunity to review the Plan and indicate their concurrence and acceptance by
signing Safety Plan Review Checklist. T'he Safety Plan should be a dynamic
document which is revised whenever there is an safety incident.
The Safety Plan is implemented through a Manual of Safety Procedures.
These procedures govern the operations at the site and typically include such
items as lock-out tag maintenance, confined space entry, respiratory protec-
tion areas, respiratory protection documentation, visual inspection, safety
reviews, protective clothing, hardhat color coding, sampling, and hydraulic
equipment, electrical equipment, and power machinery operations. Some-
times safety procedures are coordinated with union contracts, and in that
3.39
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i1!!|:ill V, l!.llllllii, ,l>.". n'lfllli ''KlhlllJ1 ilili:!! I1 ' I"! '':|, i ing j, ;' iiiiii'i" ,'. jjlf mii'iiij ,.(ii',"'!],; 'f'liijij'i i'JIfi "jiiti'i' ii' yiHi:,'1 H',,w;,; vxx r i ;.t;. i.xt-t lu -''.'in.! :ป"(p<ปซ*ป , i }""" "i-" "J j " "' i"1 J r1 " '*'? '. '"'
must be trained in the general safety procedures and those which pertain to
55=;Tf \."ฃ '" i ''^..^yx".- =:ii? 'ii;: their work.
SEff'rTh i''"ail''!1 '',, iiiii" jus: ', III. "jiff .iiiiii, n"' i:""; vi;,:,:1 '. " 'MS i" ซ ii : in in ii iiiii mi in i 111 ii ii i iii|iiii iiLii'iii: iii'''t:ii'iiiii ujiiiii ""; .'K1'!! L/'yWi'i.iflw ;ป*. ',';*'< i
===ฃ.; '; ;ฃ, ^t'ซ /I .' i= '""i;1' 3.8.? l^ejltificptkM^of Safety Hazards in Design
iiiijS f'!i""i"'il>! if." 4, iiiiii'1', "i1*"','"i' :', "'ii? '..I1' ii,!'; i;!iiiiii ' ;",:i' '""Si!" r ; "wi if: "I :ซ '*:":, "'tSS' S"1 "iii"": iipi'"" "tt^"iirw'.SiSiuiifiS1 t'wJ'Mli'iraLi.'iwjS.IniLiiiBR.isi!
|| j; ": ";;;'|i''"-;""" i ' | |i:";; *h :> _;_;>' -'-^' ;^ ;';ป"" ' .Many potential safety hazards can be eliminated in the design of soil
V"' Si &:?$!ป'; 'Jl 'ffl/;|y^ing"facilities.' Some hazards are'eiiniinate3'b"y me component'equijp-
:1::'"' i"t 4," * r ' ,-:;4t"iซf."" ment manufacturers by following the Underwriter's Laboratory and National
Fire Protection Association (NFPA) codes. In such instances, the safety
r f ^-"; f _ ,::;7;; ;"' -^ ;;;;;;;; ";controls must be'reviewed, to, ensure "that they meet the operational and safety
standards for the site. Other hazards are minimized or eliminated in the
"!' in, ii lilt' i ,,i,'! ; I,.1 ,111 !, n iii:1"1 i,;: , , iiiii; ' m "" i'; "liifciii'i"1 !i: ""iii 'Hi ymM *>*:ฃ;" 'if 'f "*>';!W;t-Wiff^i^M myiwJSn in II in 11 11 1,1 .> i> j "; i M
IIH^^^^^^^^^^ ; ซr=i:i",' i,, iiHt;:;:,: ;/;_ii ,;ฃn,, I,,;;;:;; i j,: t 'Special precautions may be warranted during facilities construction instal-
r_=^r ^:-=:": : =m'; "': /"; : =::; ;=."";lation. At that tim^ the site is full of heavy ^equipment ^and ^there are many
"" """""''' """' "'""i' _ " " ''_' ' _ ' ""_ i ' '"''' 'danger's "such as cnisliing, dropping, or "other SazarSs relateS to moving
heavy equipment on and off trucks, cranes contacting overhead power lines,
insufficient soil bearing capacity for machinery loads, front end loaders
! ' "' Pl1 ":" ' " '""" "!: ' " ; " '' ' "'woVkTngTop'Ho'se tothe'edge'of an excavation, etc.
r i *j< iv |","i: wi^1 .f../; r I!!;'-!" " j < Decontamination of equipment is an extremely important consideration
during design. Every piece of equipment being brought on the site must be
decontaminated before it leaves the site. This is especially important at sites
'i"L!'i:':'!"'r='?' " > ' 'Ki1!'" "" "'I"1",:: .iiiss, as*. iWhere nuclear wastes are being treated." ATthe'Hanford Nuclear reservation and'
,"ฃ,::"; ";;;,, "i:,,:,.,.,,' :",,,.' ^ 'i;:;,;;::'' other DOE sites, it is notwcommpn to ^^ojnฃlex e^mpment iwhich wasi
abandoned by contractors because it could not be successfully decontaminated.
^iiss , :i; ^!?"j,.;: j';", '^;''"i"|i ' ,'"i::; ,i. i\. Typieallyfthe Safety and Process reviews a^~"gO-n"gu^:je-g"ia||er g^e desvelbp-
menf of me Process and testrurhentation Diagram (which is equivalent to about
10-15% of the completed design), at the 30% completion level, at the 60%
iii'iiiiii:!!,, i'i,,;, i,::1'.!, MII iii; i<
; ir i '!" ;Si!
3.40
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Chapter 3
completion level and again at the 90-95% completion level. These design re-
views grow increasingly thorough and complex as the design is finalized.
The Process Safety Manual (PSM) development should be started when
the P&ID is finalized. The Process Safety Manual is developed from equip-
ment specifications and design considerations. The PSM is completed as the
final equipment specifications are developed. Depending upon the needs of
the PSM review process and the degree of hazard associated with equipment
failure, the PSM may be a very thin or a very extensive document. When
completed the PSM will become a part of the operating manual and will be
cross referenced to the Safety Plan.
3.8.3 Personal Protective Equipment and Worker Safety
The specific personal protective equipment (PPE) required can be mini-
mal or significant. Many of the hazards at a soil washing site are dust haz- .
ards, but chemical hazards can also be present. It is important to consider all
the chemicals on site and the conditions which the worker may encounter.
The degree of protective equipment appropriate to the hazards present at the
site should be specified. Also, entry and decontamination zones should be
established according to the degree of probable worker exposure. The fol-
lowing suggestions are offered.
If respirators are to be used at the site, all workers requiring res-
pirators must be fit tested, and that testing documented and main-
tained. This also means that there must be a policy prohibiting
facial hair.
Safety equipment is often cumbersome. Work schedules and activi-
ties must be able to accommodate this reduced productivity. For
example, in some instances, additional layers of protective gloves
may be required making it difficult to pick up and use equipment.
Hard hats, eye protection, hearing protection, and safety shoes
are almost always mandatory. If hearing protection is required,
the workers must be made aware that specialized hazards are
created when workers cannot hear heavy equipment and alarms.
Communication by walkie-talkie and/or voice-actuated intercom
may aid coordination between workers and heavy equipment
operators and control house operators.
3.41
-------
Illiill IIIIIIH
II" IP ;':F '<:>Sllti HI l!,i|iii|;ฅ'i,i'sit (TUT t'1 'MB" :| !!!
JlliH^^^^^ I
Design Development
>nn I I :' i Inllii , ICiii!1' i I , ,,'L1" il'HilUiliiJ!'11 Win, ' ,,, lilt! "IIII ,1k
i c ni; ; 'iiii' , i' ill11,,,,, ;, ,, 'i 'f; S, ii din '; iiniiii " n,, u
ii y iiiii '':.i iii?''i: :f "''. !:MJSi Jill :r/,.',: '; B,i ,, :!
"!! IIJ! iiiii I1 T"i,,,i I1'
Many workers will be allowed to wear only coveralls for protec-
tion. However, mere may be other potential chemical exposures
which need special protection or even Self Contained Breathing
Apparatus protection for their work.
" For mo^^azard^ous waste 'bperations,'especially those where
protective suits are required (which can add up to 20 kgs of
, h, . h( jf , j:. |P ,, y ( ,,, _ , ,,,,,,, ,, '^ght arid bulk), the three-person buddy system must be used.
: "'l| ''!;'" -"'' '"' ' "' :":!li !"""'''''"!-'' '' "'-'; '"" !'' -*'T^is s^stem*en"abTes"KJo to rescue one wno'sufiers' a physical
problem or injury. Standby personnel should also be available
LiJSili*;;1 ;'i !!!;'' ',":i' 'ป!* "i i;** ! >;:!! *ซ!2" ^s ,' ,!*":; : ;!,:,j;:; - y^;;: for rescue during hazardous operations.
t^i; ]i& tin fit '' iiiii S-l'i'1" i I: jit"Si"', iMHNฃ'' III ;:,. ปL" ' liJIiili, i i . If Ilia' j i. % ^ ;!" *'it Aฃ 'S^S^fiA ii,'' i: SK'^K' fflS^ W0(. sS'T Ii-' StS i -i ' .ftti;,,! .*' ซi"!" ' i. lit''. / ^I'la1
TJ^-^ "';;";; | ^ -1;;;;;;-;; ;; ~'.m'" ~ ,, ";' .;,'; ", |"";,";ป~'', WOTker, training is an effective tool in creating safe work condi-
:;=;..;::; ;;;,,;,,;:, : .;: :;;;:::';;';;;.,,;;:;; T ::.::;;;,.. = ,.,,;;', ,:;;:::;:;,::,;:,::;:;,,,:;,, tions. This training can be a combination of classroom and on-
the-job training, but the training must be documented and the
ieptina" separate;
,'. ^T,'",.vl' i, '.=;' *ซ,";.;,",. ,;,. ,;,;: ":: Medical examinations, which include enzyme blood work and
, * , i . , ] ," i
;,, ;;-;;;:,;;;, ;;,;;;;;; j;;;;;;; ,;;;;,;,;, ;;, ; ;!1 '-;- StreSS testing, may be nCCCSSary depending Upon the type and
- ! 1!'"" '-' w-: :;i J ' ' ' *"- "*"- ;i" ' * level of exposure. These decisions should be made in conjunc-
i.ii ii i; i''1. 'iปwi;;i; iaiii:':" '*m -."',. i"''.,,,ป, _w::" r'V ii 'tiqn "Kith'a"" qualified" physician or health professional.
All emergency response personnel, including fire and rescue,
hospital emergency room, and transport ambulance personnel
must be made aware of the type of contaminants on the site so
" ''"" "" "!| '*:"!" 'that'they can tyce^appropriate1 jprecautibris to Hecontarninate an
injured person and protect the emergency equipment, facilities,
and themselves. This is best accomplished in advance of any site
, ^,, ,,^,,-, r.gmf i,|,ii|, .. ii. C ;i ^7isS P^iergencyi "
l>-i^-] :l'"'!"i'' "''':*''' ' '* '"f'^' ::':i'"ซ:':'-!l ll!^^^ ซ:' $" i"?';""!:"'i|l"!i:'"" ''"lli!"'Safety 'arid fire drulsJs'lioiu'li> be marioatory! It is always a good to
plan for emergencies and then during the startup operations conduct
:; a^ test tKe Safety Plan arid procedures.
'in!, I',: In MIป :'" I llllli""ii""H"l|ll ih'I|l'inliNij|oi ! ""'" l|i.::i'|l|'|iiiilp.'"" | SI' ,ป'!!!''ซi ,i
An emergency response action plan a plan of whom to
notify and whicb"acHons to'taYe'in itHe'event of an emefgericy
, should be provided "to all potential emergency response agen-
cies. The plan can be relatively brief But should cover man"y
msiiM "!%i.:r '"'i' ' ,. ,* ,n ป,'!,,:, ,,, : i.'v.,i .1 :, of the likely"lls-cenarios which can be reasonably anticipated,
such.as electrical fires, electricshocks,equipment fires, per-
^^ : ~-ป " ~ """ - ~~* '":--- '""" '!''. " "" ''""" ' ' "sorinel injury, spills,"other releases, and night and unattended
operations where appropriate. The plan should be sent (via
!"Siii.i"i iiaiii,;,;, ti" '*; ,-
!
lllftl/lllilllllVI,, > ,111!I Illlillnl! .M'TIK,
[| I',!;!,! IWliM' ! ,,,,' .inlal'Ill" Ihllllliitl ' iLi, ' ';,,, ',, ' , 'I11!!111
J" ""
ป,;*!! It
,,, ,1, '" il1 ?! " " IIRIilil'iiIlL '"Huh,
i'liiiiiiiaiiiiiie^^^^^^^^^^^^^^^^^ iiiiKiiU^^^^^^^ in i,',, iiuuii! ii^:iii]iivB^^ iipit >' ii!,,;,;iiiii,:iii,;!iiiiiu^^^^^^ iijiiiiiiiiiiiiiiri^^^^^^^^^^^^^^^^^^ siiiiiii||piiii;;,jii;!it!,;i:::;ipi;,ia^^^^^^^^
-------
Chapter 3
registered mail) to the local hospitals, fire stations, and the
Local Emergency Planning Committee.
In 1997, NIOSH published new standards for respiratory protection (see 42
CFR Part 84) which changed the definition of particulate and vapor protection.
This new rule effectively voids the older classification of protection against
dust, mist, fumes, and radionuclides. The newer standard has nine classes of
filtration protection three classifications of filtration efficiency and three
more groupings relating to the filter's efficiency in removing oil aerosols. The
new standards are a substantial improvemenl: over the older classifications;
references in the Safety Plan must be based on the newer guidance.
In some states, the Incident Command System is used, which designates a
specific official as the Incident Commander during a specific emergency.
Where the Incident Command System is being used, the Incident Com-
mander has control of all the assets of the site and the companies who have
financial responsibility for the ownership and operation of the equipment
and the land on the site for the duration of the emergency. The Incident
Commander may, if he or she so chooses, order the destruction and removal
of all the equipment on the site to mitigate the emergency. It is wise to keep
this contingency in mind when developing the site Safety Plan.
3.8.4 Site Operations
Sometimes, the site remediation facilities will be operated by a third
party who may or may not have been associated with the construction of
the equipment. In these instances, the operations contractor will prob-
ably have his or her own safety professionals and engineers review the
equipment layout and operating plans ami will want to incorporate their
own safety plans and equipment into the site operations; however, such
plans must be subordinate to the site Safety Plan.
Regardless of the operator, all OSHA guidelines regarding worker train-
ing and jobsite conditions must be followed.. These are specified in Part 29
of the Code of Federal Regulations, and worker training and safety commu-
nication is specified in 29CFR1910.120, and other paragraphs.
OSHA has developed a Process Safety Review program for site opera-
tions. This program requires a detailed set of process control procedures be
developed for the site equipment which defines normal operational control
3.43
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,! ?,
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Chapter 3
designed excavation,
health and safety, and
full-scale process design.
Throughout the development and design program, the ultimate goal is to
develop a site-specific soil washing process "flowsheet" or design (and
project implementation workplan) that will accomplish all remediation
project objectives cost-effectively. Specification development, or determin-
ing the project goals and specific project requirements that must be met to
ensure success, must be a major focus early in the overall program. The
detailed process flowsheet or design specifications will then follow logically.
There are several ways to successfully accomplish specification develop-
ment. In traditional serial (sequential) methods, the customer typically pro-
vides project requirements to a research and development (R&D) group,
which develops flowsheet specifications from these requirements and opti-
mizes the process or product. Usually the R&D group is left on its own to
perfect the design for full-scale operation. What typically happens is that
project goals and requirements change and the R&D group's original design
must be recycled for re-design and re-evaluation of requirements. This natu-
rally results in delays, inefficiency, and increased cost. An innovative alter-
native, which is gaining popularity throughout U.S. industry, is "Simulta-
neous Engineering" (SE).
SE provides an organized method for individuals with different functions,
responsibilities, and technical specialties to work together as a team to de-
velop, design, and validate a process or product. SE team members use their
combined expertise and knowledge to accomplish the task simultaneously
instead of serially. The team leader is responsible for resolving the inevi-
table conflicts and keeping the overall development/design program on track.
Several of the characteristics of a successful team are shown in Table 3.4.
SE stresses that most of the effort be accomplished early on in the project,
when there is maximum flexibility. In this way, SE avoids many of the prob-
lems associated with the traditional serial methods and typically shortens the
timeframe for product or project development, reduces cost, and improves
overall quality. It is used by many leading companies, such as Ford Motor
Company, Martin-Marietta, Monsanto, and DuPont.
3.45
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Design Development
if fiiillLiilliii't:'1!!!,'.1' ..
Jl&Bfc
Table 3.4
Characteristics of a Successful "SE" Team
Team members are able to meet and communicate regularly and keep each other informed.
Appropriate skills are represented on the team.
Appropriate levels of organizational authority are present within the team for effective decision making
" commitment of funds.
AH team members are involved in setting project definition, project requirements, and time deadlines.
Progress is set with realistic time frames and tracked regularly.
Individual roles are clearly defined, don't overlap, and are supported by all team members.
ill in n iiliiii in ill i in i 11 i i in ii nil in i i i in in i iill in in i n i I 11 i ill , i j
Team members and the team leader understand their assignments, tasks, and time deadlines.
and
ii, l||iili|||lllll il111 |1 1 ii|lli|ii|lli I1 i Hlli Jillliiiljlliiiliilil 1 ill
ii members and the team leader support and help each other
ill 1 II
Team
Decisions are mainly made by consensus and only rarely arbitrated by the team leader.
Team emphasis on solving problems vs. placing blame.
All members actively participate in meetings and communications.
:;,;;;;;;,; :;,;, jhe team has an identity and mutual respect/admiration among team members.
E"'1'":,",,'"' Conflict is" openly" d^cussed/often resulting in m'icaT growth" and leanung^by all' team members.
......
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"ป 'Hi11,/ ...... J!""il'i'iini'i!', ll'FB'ift, ' ii'1 I1 J"11 1,,: 'I'" nilhH'Jioi 'III1"1' !' ,|, ,: I, "!
'' ; Jijiiiiiiiiniiii,, iii,':1;"1! ,,11 ...... lllnniiMl iM ' Jii"11 Lfitiinl' iihiJEii" JH'ini! :j , # |, ^ , \\ ;,' g r1 ,,1'f ,
1"1 ' ป,!!" " HI1' iliiM'" ' "niill ..... :n'4" Ol :;,r :l, H "'illli-l IP'1 I,, I il,1* V ':,if ' ..... ir'.iJir'li.vJJ1
i i ,1 'Uiiniilihlllifiii ' <ป ;ig iปi ........ ;:, v a .,1, i, m ..... ifl, : pit ; . ;,;:: ..... | , | ; T^IIIซI ' 1 1 aipii, ; " >, gi ,;,;, gi" , ...... jnniiL , < ''iiiii , ,;, , <;
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tasks of the SE team are to:
''"" ..... ';" ' '
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3 project goals and requirements,
generate ideas and develop the best process, and
complete the full-scale design.
in ii i i i i i i in i i i i i INI in i!!!!&';i<3ง!ST,S W.Sz^WSWi:! n i i i i i i i|i
Defining the project goals and project requirements includes identifying,
collecting, documenting, and prioritizing all goals and requirements that
must be met for project success^ For a soil washing remediation project,
""'"" requirements can often "be" gVbupetilrito'ca'tegbries" wEich might include
technical parameters (a high prbces"sing fate), regulatory considerations (an
easily permitted process), customer needs(acos't-effective process), and
public acceptance (minimal emissions and noise). The requirements that are
identified represent what the SE team members believe are critical needs to
make the project successful Arrangfrig anTSbcumenting the requirements
in categories Helps keep m^m organized and facilitates comparison. The
team continuously"updates project goals and requirements.
3.46
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Chapter 3
The SE team should also rank the importance of meeting each require-
ment; that is, whether meeting a requirement is absolutely critical to project
success or only a desirable option depending on cost constraints. Ranking or
rating each requirement provides a quantitative means to establish tradeoffs
among all requirements, although qualitative considerations can also be
used. This helps to avoid making critical decisions based on emotion or
"soft" reasoning. Although ranking can take several forms, a simple, com-
monly used system is to assign a numerical rating from 1 to 10, as follows:
10 A critical need; the project cannot be successful unless this
requirement is met.
8 An important need; the project can only achieve partial suc-
cess if this requirement is not met.
5 A strong desire that will enhance success, performance, and
cost; the project can still be mostly successful if this requirement
is not met.
3 A desire that would be good to have if cost-effective; it will
have little impact on success if not met.
1 Of low importance, good to have if at no expense; will not
affect success if not met.
To the extent practicable, a tangible measure of success (a "metric")
should be assigned to each requirement to evaluate whether it has been met
by the development and design program. This metric essentially becomes
the detailed design specification that must be met during laboratory treatabil-
ity testing, field pilot testing, and detailed design. Several common soil
washing project requirements, possible rankings and metrics (design specifi-
cations) are shown in Table 3.5 This is not intended to be a comprehensive
or exhaustive list. The final list of documented, prioritized requirements,
and related detailed design specifications can serve as a guidepost for the
team to routinely revisit and update.
3. JO Cost Data
All remedial decisions are based upon cost, risk mitigation, and site-
specific factors. But, cost is by far the overriding decision variable.
3.47
-------
:'"-'" "-'IS ' ' " I! :
i'L ""i!!!"!liililllil '! Ill
f ฃ >''*' ''"'Design Development
1.1. PH'tlll... "111! Ill' ''(I,
if:"''" Sis,,, ii 1',:!;!,"!;! & I Btfelr i IS Sifti HK I'" :,ii ISS'lil fcUtTBliW ,i W i Ii1 Wป:,,! mW& ii ^ M
THiJ 'it , 'Illii, I'lRl l||ii|||,,||l|i; ii I'Jliliiiili, ""II '.' '"ii'l"! i"'! , ' "" ,|i >, i : ' F ,j ' : ,!',>" ':i|'!!|!"i|(,l|" ",;' At'' "*,l, ill!""!,,i,'l '"'Ml,, III!1!"Si'" JIIIHII !'"'!, if* li'IK, !,,i;iii.!.i::iii' 'f .i~ ii=" ' ' =!' 1' ':'"',:"'I'*'', ""~.i=!"'" -II :!-!l~'' " ::" ' !" \. Typical Soil Washing Prpject"Requirements
,;;::'';"": :"'" " ;:";;:; ,:;',;;, r^'arld Detailed Design Specifications
* i: "<' ,,;;'i," *:" in ri1'*,".L i" v^wr^'ftv f''"!,}'' '"-:-:<&. ปซ^^^^ :ii.jiaitjiiiHปfflftm msxs'K^,s, &,; i,:?!:"?" srFnai ;m.
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"'"
Number
Requirements
I ' Design Requirements
Category Rank (Measurable Metrics)
IMI. riiiii i ? 'itf , lilt" , iM 'ii'i'iiia1
Excavation of Soil
C 10 Compliance with OSHA
i _ i i ^ ^ ,,,,,,. _ ,, .,, ,,,,,, ,,,_,,. ,. ,,,,,j .[^^-"J&ccijvation, S^1,^^!
,"' "i?' I,- !; !, jiiliiiii jillli, ,i I:'"1 !i; hi!!iii,:!;,!!',! i'! linv
2 Implementation of Excavation Safe^ C 10 Favorable Field Audits,
Ifjli!,!!,,!,,:!,;: Jiiiiiiiii'iiimiiiiu'i. ' .',,1,11111,
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11:1! ix 'M J it
Completed
!';,:T, :!l i .,:lll"l|f' ' ' " Obtain Permit RCRA Part A
ง Obtain Permit Local Construction
i,fiii':':',""' 'aii'Tio "" Obtain 'Permit" Local Electrical
/11^|;,,,,,"; <'(!,";_,;[ y _ Obtain .Permit CAMU
12 DOT Regulations Met
m 'xm-'m.m' ^wsflfc T'5Sป ^iLa^n**
iriJlHIl . i .i1.1!':11 '!!"' , '.li'Ji /.ill'llllMllll'lIIIHII'll.. iillMilllllli ' ',', BiBJiiiJ''!'!!1111 _4 . _ ..
, , 1=1,1, - si, 14 Low Level of Lead in Treated Soil
fJJ *: ''"' ;^: ": 'ป.;]f|'S ?ฐw.ir R55u're^
:::::";: '.':. ",~ i& XRF Screening of Excavations
! ;,,; ;, ? '",;,;; ;; i ^ High Percentage Yield of Clean Soil
Tom Debris
C
II
R 10
R"""':I:" ' "':":'"lo"'
.1
Yes/No
Hi iiiii i' 'IPi' iilllii'"1"!!,'!!.'!
'iiil"!l ,ili,i, iillliiill'Ii ,111',,, 'liiJIi'iiliM'Miiili'ii Iiiii,.,' .iiLplli "Illilli;:"!',:'!': ,'l, ': 'i"! ''"ilii,!"1!1:, 1 O
,,i"" , iiiii"i ii. i,, ' iii,:iin ::':'ijiiiiiiiii" ii'iii.!'!!!!!;!" , iiiiiiiiiiiiiiiiiii, ,i ', i ",|,i,ii":,n ::
l,; i: , iiiii f, .ii'ii' ;,j; is if ii;! ii" 'S'liii; ((iii r ; *:,;,,' i,'' "fdii1 'j1,; |. jjii.. w i t,,, ii'i-jnii, ill!," MBS iiiiii'sn i i j* i ' j
*i!.?l*lMlL^*!!&'M.';;!:'.i?,: \;:<\\?.l Lbw Level of Water Contamination
iiiiiiK rn.'ii iiii]^ 'iiiinii Rii): liii iiiiF j iiiii'1' , >mi,. V: ซi: "wii;. iJiiiii,ซ:. (by-product)
ป ' ' ' ' '"'"'"' ". ' ' " ". ' "< -20 Treated Contaminated Soil Lead
Concentration
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R
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, f
Yes/No
'":'Yes/No
10 Yes/No
10 yg-j^ij
10
8
10
10
Yes/No
Yes/No
< 500 ppm
Yes, Define Quality
1 8 "YesTNb
8 570%
8 < 10% Soil (by weight)
- :::: ':': T '' '"' ""'"''Meet WWT Discharge
Requirements
4 > 1% Lead (by weight)
"g " ' ""'"' Customer Requirement"'
R ttiguTaiory" Requirement
T Technical Requirement
PSA (Pre) Pre-startup Process Safety Audit
WWT Wastewater Treatment Plant
m,i|| ... ' iWI'Mlli" ' IIIII1.. Illiliilll..in ip 11.1
'.:' n:1" .'Ti, i||'iiHii|ii,l" I, , t , II .,n..||lk,! to k ? "Ill if I, ill" :,,. llil^llUlliPILIIIipiillil I " U1. ;,ป nil!1!!"" J* .1 "IPi! nh ,i flilillli'liilli'ir!
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ill, .'VKttiti'fl.l.lll' ':' t
nisi...!::;1!"1;.,.!'!,,; TUWM .*.';'a .. ;"":.;' i .:.^'T,*!]^1 .,,''ii'!"i,":' 'i. :i:,,,' ''!i::,siif'i!ii;'i=J mmฎ, sumj-
II,' :"'"ll,i,'l", !,' 'jlli!,:,; ,,!: 'l,,i''lilil: ' ' -i-' ,: i"',",; *r; > *i i'!;,, ,;,:: ' :.:' .: !' 'i ., l 'iiyii",,*:,! 'Hi > :tgft^i f',ilfi: liKlill i i B 91" '"fflie i >i;
ii!!! ,iwa^^^^^^^^^^^^^^
"'Ii' 'iB llli|i,:in
3.4
-------
Chapter 3
One of the most common sources of confusion arises from a failure to
clearly define what is included and what is not included in the price.
The purpose of this section is to highlight the basic variables that affect
a soil washing treatment system and to list the cost elements that must
be considered in preparing a cost estimate that can be used to compare
soil washing and other remedial alternatives.
3.10.1 Cost Variables
The key variables required to estimate the cost of a soil washing process are:
the volume of soil to be treated in cubic meters (m3) or cubic
yards (yd3);
the approximate density of the soil in ton/yd3 or tonne/m3;
the particle-size distribution that quantifies the percentage of
the target soil that exists in the oversize, the sand, and the
fines fractions;
the end use of the soils;
the schedule under which the project must be completed;
the key contaminants, the feed concentrations for such contami-
nants, and their respective treatment standards;
residuals management costs and standards;
the sampling and analysis plan to be followed; and
the treatment goals for determining success of treatment.
3.10.2 Capital Costs
The capital costs for soil washing are usually limited to the treatment
plant and supporting equipment. Since the average quantity in all currently
identified projects is approximately 27,216 tonne (30,000 ton) of soil, no
single project can bear the entire cost of a treatment plant. Thus, only the
applicable depreciation is charged to the project. In some cases DOE is an
example), the project feed is so large that treatment may go on for 10 years
or more. In these cases, the entire cost of the treatment plant may be recov-
ered by that single project. There is no fixed depreciation life for this equip-
ment, although mining companies depreciate similar equipment in 5 to 10
3.49
-------
jjjjjIK ,
jlJlJIII'lilliniiEliJi!!1'"!:!!: 'Iftufftiiff i fill ;' 'J" V'l^j,;'1;,,,,;UiVir, j!,, Tinilll j,,,., hiiiililin ': v\.""ifi"tsI,, 'i,;!; "';,p L
iiijii m \ ins K!:I i nil ji;
r:, i;'Jill ih:fr,:^:} y>,t' , hvirijiir.':.!;!!!1!!;, /wi^ iii ,.! hi |i
:, iijitff ;\,i,i; Siis, 'fitiitf &W-M&* 'if*
iiini:] iiij, -iii'iiii ], xs ~ : " iiiini''iiiii;1 ซ'",, i iiiii in ill i
Design Development
IIFI!!11!!'!'!*!11!,;,!:, ikl
IllilUi,; nil, "PS ill'"
t' '.
..... '
wit 7 years
) ........ .......
common. Generally acce
1*;: rin, . ...... .H
::-r*#
It, IliliiiC LHdli" nHiii i,, 'fill'!
ซp
accounting
oF a "use basis" depreciation method based
sn. :the actual tons ....... processed. "Remediation contractors will decide upon
, ....... ;'isi.;: !^'ifce..approach that best fits their business practices.
'" ............................... ................ ' 'For'a ..... frame of reference^ ..... a ..... 23 ..... fonne/hr (25 tonAir) soil washing plant
with ."'feuifflii ; flexibility of treatment unit operations costs in the range of
$3 to $5 million.
operating costs of a soil washing plant consist of the following items:
j|i] %*'''*:& ':Han/|^prrThe p^^o^
':" ' " ' '!:' "1I^MSESBc^li55's oTthe system" Incf will include, in some
*ฃ:. ^pom^a^n^'ajgilaint manager, a process engineer, a health and
Jl|;"' ": Safety "or^e^a health-physics
technicians (if radioactive materials involved), plant operators, a
plant electrician, and laborers.
plant "Consumables. "Soil washing systems'''vary widely, as does
7,~I the use'ofc^^cdsl ac!3s, causTicsj surfactants, "ancl polymers.
i"l:" ipj^t consTima^Bs fnC"Ju!3e cTSnTicals", p"r-Oteฃtive clottiihg for
workers, and other non-capital replacement items.
Utilities. 'This cost element includes ffi^costof commercial_elec-
trical power, process water,: and, in some cases, surcfiarges levieS
by the POTW for the discharge; of wasfewaten
Process Analytical Controls. Process and system controls focus
on the control of physical separation, the chemistry of treatment
units, intermediate process quality, and sampling and analysis of
the oversize, sand, and sludge cake.
1.10.4 Support Costs
i*
MMFkLV'T Mffi.'"
', ..... '
'' ill ,*'. ,*'-
ป'! if! :;l!l'IJ!
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iiililiiili"'iilit I I 'in: fili,,. ':
i in iiiii 11 i in ii
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There are'asiMfficanf number of support costs that must be considered
; , IILi-llsjii'li'l' ..... , r iiiliiVI^^^^^^^^^^^^^ ........ ' . iii ; Ssfa ...... n ...... iiiin '"*i- ' i1 ........... ............. " ................ ; ...... . ..... iw ........................ ................ ' ..... ..... ............................... rs ........................ ; ........................ ป ................................................ : .............................. i"1 - ^.". [[[
included in a complete remedy cost estimate. Support costs are.
/ii ....... iiUillllin^ ........................... i .............. i ............................................... i ...... iniigiiiii 11111 .................. i ................ ........... i ..............
liiii1'11!,,!111111'!11! I'l1:*:
iniiiiH i mmiiiiป: ;<,ai,' iiHiii,!'1,1 s, ,
{ 'I'i'F1'"! ifil'P'i'i'1 l!'i|E:!|1 '"'Illlilli 1H11 ri"'111!*1'1 , ':liii I1
,,!isl4 lii,,,, *'!i!,l, t!;i:;|i!!1
Mobilization and Demobilization. Mobilization and demobiliza-
;:_: ; ;::; , ,;, ;,: :;,;,;; ; ; ;,';;; tiqn include^ transporting of the treatment plant to the she, erect-
and connecting the units, and dismantling the plant upon the
(i,i:i:i ;ri i. ,':,:';!<:
-------
Chapter 3
Site Preparation. Site preparation activities will vary widely based
on the specific site to be used. Site preparation activities may in-
clude constructing access roads, clearing and grading the plant
location, constructing a plant operations pad, constructing staging
pads for feed and product soils;, erecting a building to enclose the
plant, installing a site office and personnel decontamination facility,
and installing fencing and hiring a site security force.
Site Administration. Support costs for site administration may
include hiring a site secretary, installing phone lines, setting up a
fax machine and a computer/printer, and paying for mail and
overnight delivery services.
3.10.5 Materials Handling Costs
The costs of materials handling to support the soil washing treatment
must also be considered. These costs include:
Site Clearing and Grubbing. This includes removing, staging,
and disposing of existing vegetation in the area(s) of excavation.
Excavation. This includes the excavation and transport of soils to
be treated to a staging area for initial processing.
Prescreening. This includes separation of oversize material (usu-
ally >2 in.) and undersize material (<2 in.) from the excavated
soil will be prescreened using standard equipment such as vibrat-
ing bar screens ("Grizzlies") and rotating trommel screens and
staging of these separated materials.
!
Feeding the Plant. This includes moving the feed soils from the
staging pile to the plant feed hopper.
Managing Clean Products. The clean products include the pro-
cess oversize (gravel) and sand, which are staged in separate piles
outside the treatment plant. Normally, the sand and gravel are
mixed with a loader to prepare the material for movement into a
designated portion of the excavation area as clean backfill.
Regrading and Revegetation. After completion of treatment and
when all the materials have been backfilled, the working site is
regraded to designated elevations and then revegetated or re-
stored to a condition consistent with the final design.
3.51
-------
Ill HI
111 111
I 111 II
I III III
Design Development
ii|> il ii1 ] *iiiiiHli "ซl iliri, r^i^'S^^S??^!'??
JS"":^*11^ 'ปซ*''" '.''""iซ'\^'j':h.*j "*'':^ LOyerheaci.'and^contingency costsmust be included in the overall cost esti-
mate: Individual contingencies may be allocated as they occur, but an over-
^^'^^ ;;,;;; ^j; ;:;;; '"~m r^",:=v!,aflrconSri(gency factor of 10 to 20% is common.
'ti ..... warn ............ a, ........ : '-mii'in ..... m. ..... T^(eni':ซซ*( ...... i-;; ................. ne ....... T- ..... nJBHฃSi.-^,iiw'a; ...... rsm ..... N ........... w>m'
, ,
, j;,1' it vim ..... ป i "r ..... LI,,,: ..... t s"".* i! "'inn ......... irj,, , is1' ,ijii! ..... IIM '.>
ITT'llliimilP'A 'UlliilJIll,;! RIIIIKl1 I'tl1'! ''il1 , 'I'll ,:,"
iilllMiiliFiH'i'ili'lilii'i in:1],', MHII vinipp 'in;"!;"'1'!,,, i
I'f ;ซ
''!ii::''r:i|lH^ JIM ^fi, >estimating worksheet is presented in Figure 3.7.
"Ill If III, fill!.'1"
jjllilljV -1 fdj ill .ij,;, . |||:;j!!;| i, lii
';, ";; i; '''f1!!!;!; i eSP'i "*""' II II II 1
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ii' I'll 'I " ' '"'" i'1'' i '!' ' ''''|ri ' ' h '"' i1
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j-,:;:!-;:
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,,' ' " r 'iPiiiin1 I,:P .iiPPinJiii ' ,
3.52
.
1 i i i i i| i i iiiiimi
i
i ' 'in ill
-------
Chapter 3
3.77 Design Validation
The key to developing and successfully implementing a soil washing
process is a careful development and design program that addresses the fol-
lowing main areas:
soil/site characterization,
i
treatability and pilot testing,
designed excavation,
health and safety, and
full-scale process design.
Design validation is a means of ensuring that the process "flowsheet" and
project work plan are correct, appropriate, and complete. This must be an
ongoing component of the overall soil wasihing project.
Generating ideas and developing the best soil washing process flowsheet
should begin with good site and soil characterization, treatability testing, and
pilot testing. The extent and degree of soil and site characterization or test-
ing that is needed is site-specific and should reflect the size and complexity
of the project. Generally, before the best soil washing process can be chosen
and a system designed, the physical nature of the soil and contaminants must
be thoroughly understood. Key factors that often influence system design
include contaminant speciation and distribution, contaminant and soil bond-
ing or binding, contaminant mobility, and soil composition. Site conditions
such as access to soil, climate, and the availability of utilities can also affect
project requirements and costs. Based on site and soil characterization, care-
fully designed treatability or field pilot testing studies (or both for larger,
more complex projects) should be used to evaluate soil washing process
options and generate preliminary cost information. The SE team should
routinely validate that the process selected will meet all project goals and
requirements cost-effectively and safely.
In completing the full-scale design, the learn should consider all project
requirements and all the information generated in developing the process.
The detailed full-scale process design should also address good engineering
design practices and standards, worker health and safety, ease of regulatory
permitting, site preparation, system mobilization and demobilization, project
timing, required analytical monitoring, process instrumentation and controls,
3.53
-------
I! II!!! i! !!?! !!! I
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ill! flii
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:;:!!!; !!; ! B i( g ji | ji |[ ป ซ|
- .1*^. ^,, =;- '.-'-.- -" - '; ; As* = " -. - v-vซr j-^, (|(: ;""."----. ^ - .- -- -:,s:
_= ^ f ฃ_ .-: . _ = - = . _*i _ -1=1. f_ f f . _i _ _5_1 s ^ = V. V - - -5-.- 1=^1 t, .-->_i_ ;|Il;:l, t - _ .._ ^ --L. _ __ ^^ . ง _ = _.=f L
it; a I
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Figure 3.7
Wastech Soil Washing Cost Estimate Worksheet
(i, 1 ! W
3T:
:cog
: TS:I ป = > i-ij j :.-:jii
(Q i
o
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CD. ,; !
BIL Li
-------
GO
en
oi
Material Handling Costs
Subtotal, Material Handling Costs
Residual Disposal Costs'*
Clearing/Grubbing
Excavation
Prescreening
Plant Feeding
Clean Product Handling
Regrading/Revegetation
Loading
Transportation
Disposal
Taxes
NA
Includes Equip & Ops
NA
MA.
NA
MA.
Sludge Cake Handling
Dump Trailers to TSDF
Landfill "Gate Rate"
All Applicable Taxes
Subtotal, Residual Disposal Costs
-X^l^-^itt^ ^^^^^"^A^X^k^^l1^^^^^ -- ;' "ฃW> ;>&?
.^i&x^*? s* S&. ;^v^-^ซ'iS4^V'^!i.t4;!c,;ซY*x ^^&A-S<^:SS,& O~ซ VMiaLc?:^
$l-3/ton
$5-10/ton
$2-4/ton
$l-3/ton
$2-5/ton
$5-10/ton
30,000
30.000
30.000
30.000
30,000
30,000
60,000
225.000
90,000
60.000
105,000
225,000
765,000
$l-2/ton
$50-75/ton
$100-200/ton
$10-35/ton
>Tons, Wet Cake<
10.XOO
to.xoo
10.SOO
w.xoo
16.200
675.000
1.620.000
243.000
2,554,200
, , x
t., v
6.394.200
General, Administrative, Overhead
Subtotal, Burdened Project Costs
Contractor Profit
5-20% of the
I Burdened Cost
VVVKX V \wซri*- 'syjiLi.^^
'Enter the Feed Tons, except In the case of residual disposal
"Assumes Disposal at a RCRA Subtitle C Landfill
9
Q
CO
-------
ill III 11 III III I I III
IK 111 III PI 1
Design Development
I!;;:
, ... .. i , . .r:,...
residue disposal, materials handling and management, and clean soil recy-
cling. After the full-scale design is complete, the SE team should provide a
final overall validation that the project will successfully meet and address all
these issues in a cost-effective manner.
A validation issues checklist is provided in Table 3.6. This is only a
guideline intended to identify the types of issues that should be ad-
dressed during SE team validation. It is not meant to be an exhaustive
design review checklist.
' '" '"Table,, 3.6
Validation Issues
Review work accomplished to date.
Establish that decisions on a best process or selected design will be consensus driven, with active
participation by all team members.
Identify the most promising best process and selected designs.
Evaluate (quantitatively to the extent practical) a best process or selected design against project
goals and requirements.
Synthesize, modify, and strengthen the most promising best process or selected design.
Make a tentative team consensus decision on a best process or selected design.
Assess implementation risks and assumptions used to make any tentative decision.
Develop plans to support a final decision on a best process or selected design.
Summarize and document assumptions, implementation risks and any key factors leading to a final
decision on a best process or selected design.
3.12 Soil Washing Permitting
liilll I I . iit,-i , :'"'i J11 ' I,1! '(, .:, ",: i"', "i 'S < '.'. ' 'I1:',!*!:!?-:1!" f if! '"i, ~:; :*V ':V: S:::';,! "'"'Ml lซ! < /'i ":1 If ! H IFIlSIV,"! : I ' 'if '. ! I,' Ji i; I 111!! ,ป'! '.! .. ,i"!E
ili'llnt, ..?' fc"'1) " il"! , '!' Li il'di '"1" ; .'I'/ll
IP1
I >!'!'
ปป'
iK1 : ' "T -.ill; VI'1 ., ''*'. !!'''Vi' ' ".:" .''';'M' :.'. "... ''*< Mฃ ri--,i.'y.}i%W'lA*r'lih,]'friii*+'^ :#',*<' ]i'ป i 'f'.ir'.iW :"', if: i '^''',,m
3.12.1 Pertinent Environmental Regulations
i ,. ' I,,1-,1,,! , ' " " ,,i i"Sj'i',,-:: 1 if !,'..,' ,iJ il'iii :i;:',,,;i'.'-i,;; r11;!;! iln,1'!, (in t!iii|ifi|, ti,; i ซ
There are two primary federal statutes which govern site remediation. A
summaiy of the purpose of each follows! The Resource Conservation and
Recovery Act (RCRA) was originally enacted in 1976. It has been amended
over the years by additional laws, such as the Used Oil Recycling Act of
1980 and the Hazardous and Solid Waste Amendments of 1984. RCRA's
primary focus is protection of human health and the environment. It also
li
'"" " '" #56""
-------
Chapter 3
addresses conservation of valuable recyclable and energy materials. Its
goals are achieved through extensively regulating the management (genera-
tion, treatment, recycling, transportation, and disposal) of solid and hazard-
ous wastes. Extensive permitting, record keeping, and paperwork documen-
tation are required to meet the regulatory requirements. Remediation is
regulated through RCRA's Corrective Action Program, which addresses
releases from active sites.
The Comprehensive Environmental Response, Compensation and Liabil-
ity Act (CERCLA), also known as the Superfund statute, is designed to ad-
dress three major environmental issues: oil spills, spills of hazardous sub-
stances, and remediation of uncontrolled hazardous-substance disposal sites.
The regulations promulgated under CERCLA are designed to provide guid-
ance for the discovery and remediation of hazardous substances and to estab-
lish liability for cleanup of inactive or abandoned sites.
3.12.2 Permitting Issues
Careful attention and planning should be given to permitting for each site-
specific soil washing application. For simple systems treating nonhazardous
soils, permitting can be straightforward. However, for applications where
RCRA- and CERCLA-regulated hazardous contaminants are involved, per-
mitting can be quite complex, involving federal, state, and local regulations.
The soil washing project team must ensure that all necessary permits are
obtained to avoid the delays and added co;st caused by fines or equipment de-
murrage. Depending on project complexity, federal, state, and local permits
may all be needed for soil treatment, soil and waste storage, air emissions, exca-
vation, impact on sensitive land areas (e.g., coastal areas, wetlands, etc.), site
construction and mobilization, and vegetation grubbing and clearing.
The bulk of permitting needs for soil washing remediation projects are
usually driven by RCRA or CERCLA remedial regulations, although other
permits may be required for soil and wasite storage, excavation, and air emis-
sions. It should also be recognized that a Toxic Substances Control Act
(TSCA) regulated concentrate can be created from non-TSCA regulated
feeds. Obtaining permits is a difficult, expensive, and time-consuming task.
The permitting process is a impediment to the use of innovative technolo-
gies, like soil washing.
3.57
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Design Development
"I'll lliRI, "I!1 ! I II1
Most recently, US EPA has worked with the regulated community to re-
vise and streamline the RCRA permitting process. A good example of this
permitting reform is found in the 1993 RCRA Corrective Action Manage-
;:"ment''Un| (CAMU) regulations (40 CFR 264, Subpart S). The CAMU con-
cept and me associated Temporary Unit designation offer significant flexibil-
ity and permitting relief. CAMUs will help speed up remediation by easing
the permit burden. The concept will also encourage the use of innovative
technologies like soil washing. Obtaining a CAMU permit is still a signifi-
cant task, but well worth the effort. Many states, Washington for example
have also incorporated the CAMU and Temporary Unit concepts into their
own remediation regulations and policies.
Essentially, the CAMU rule allows me management, treatment, and re-
placement of remediation wastes on-site in temporary storage and/or treat-
ment units subject to various US EPA and state constraints and approvals
without requiring the activity to meet the existing restrictions of:
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land disposal restriction (LDR) technology-based treatment
standards;
minimum technical requirements (MTRs) for waste piles, land-
fills, and impoundments;
I!
some of the RCRA design, operating, closure, and permitting
requirements for land disposal units and remediation treatment
units; and
typical RCRA Part B permitting requirements.
LJDRs and MTRs are waived for remediation wastes managed within the
CAMU, and design, monitoring, operating, and closure requirements are
tailored to the activities; performed within the CAMU. Site-specific require-
ments will typically be specified in RCRA Corrective Action permits or
orders, Further, standards and requirements for some kinds of remediation
storage and treatment activities (for example, tank- and container-based
systems) will be based on the nature of the treatment unit and the waste be-
ing treated, instead of the full RCRA standards.
CAMUs must still be approved by US EPA (or an authorized state regula-
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tory agency) and also require extensive public meeting and comment proce-
dures. The time limit on a CAMU is one year, with the possibility of a one-
year extension.
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Chapter 3
The CAMU rule itself lays out a series of criteria or guidelines that US
EPA must employ when considering a CAMU for acceptance. These crite-
ria, which must be addressed in any CAMU permit application, are summa-
rized as follows: :
The CAMU shall facilitate the implementation of reliable, effective,
protective, and cost-effective remedies (soil washing is recognized
by US EPA and many state regulatory agencies recognize soil wash-
ing as a good, effective remedial technology/remedy);
Waste management activities associated with a CAMU shall not
create unacceptable risks to humans or the environment resulting
from exposure to hazardous wastes or hazardous constituents;
The CAMU shall include uncontaminated areas of the facility
only if including such areas for the purpose of managing
remediation wastes is more protective than management of such
wastes at contaminated areas of the facility;
Areas within the CAMU, where wastes remain in place after
closure of the CAMU, shall be managed and contained so as to
minimize future releases, to the extent practical;
The CAMU shall expedite the timing of remedial activity imple-
mentation when appropriate and practicable;
The CAMU shall enable the use, when appropriate, of treatment
technologies (including innovative technologies) to enhance the
long-term effectiveness of remedial actions by reducing the tox-
icity, mobility, or volume of wastes that will remain in place after
closure of the CAMU; and
The CAMU shall, to the extent practicable, minimize the land
area of the facility upon which wastes will remain in place after
closure of the CAMU.
All these issues must be carefully considered and thoroughly addressed to
ensure acceptance by US EPA (and the public) and to ensure successful
implementation of the CAMU. !
Other federal, state, and local permits may also be needed and should not
be overlooked. Since this section is not intended as a comprehensive review
of all possible permits, only the more commonly encountered permit require-
ments are highlighted below.
i
i
3.59
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Design Development
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RCRA PartA/B Permit Modification. Remediation sites that are
curreritry covered by a RCRA part A or Part B permit may have
to modify me existing permit (4C, gp^ 270rSubpart B to incbr-
pofate a soil washing pilot studyor 'full-scalei remediation project
(soil washing treatment system).
National (or State) Pollution Discharge Elimination System
(NPDES) Permit. The discharge of wastewater from a soil wash-
ing system or other aqueous wastes (e.g., spent leaching solution)
may require that the site's existing NPDES permit (under the
Clean Water Act, Section 402) be modified, or it may require a
new, separate permit for the soil washing system discharges.
Air Emissions Permit. A federal or state permit may also be needed
to address potential air emissions (dust, vapors/fumes) and odors
from the soil washing process caused by contaminants in the soil
mitrix or process chemicals and 'additives used'in the soil washing
process. In particular, certain toxic organics, such as benzene, will
require additional attention and safeguards to prevent process emis-
sions and personnel exposure. First, care should be taken to avoid
< using additives, leaching solutions, or process steps that generate
emissions. Then, to the extent practical, process designs should
incorporate engineering controls to minimize emissions. In particu-
lar, for soil washing applications that address soil contaminated with
volatile organic compounds, special attention should be given to
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ensure that air permit issues are addressed.
Soil Erosion and Sediment Control (Excavation) Permit. Many
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states and local authoritiesrequire a permit or written plan to
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ensure that control of soil and sediment erosion is properly ad-
dressed during construction and excavation operations.
;. Wetlands Permit, If soil washing "operationsi havethe potential to
adversely affect sensitive areas, such as wetlands or coastal soils,
the applicable oversigKt re^atoiy agencyln cn'afge may require
a permit or plan to ensure that the potential impact is minimized
of at least managed effectively.
Site-specific permit requirements and clean-up goals for both soil recy-
cling and residue management should also be negotiated early in the
ferlediation project process. Trie reusing or recycling of clean soil on-site
II!1 Ill MM II
3.60
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Chapter 3
and the management and disposal of process residues are key issues that will
affect required system performance, cost, and the ultimate benefit of using
soil washing technology. If clean soil cannot be recycled or beneficially
reused on-site, a major benefit of soil washing is lost. Clean-up goals can be
based on total concentration or leachable concentration, or both. Project cost
and scope can also be influenced by other regulatory permit conditions or
requirements, such as requiring soil amendments for treated soil after treat-
ment and prior to recycling (to restore original permeability or ability to
support plant growth) and restoration and revegetation of excavated areas.
Since all these issues are driven by clean-up goals and regulatory compliance
and permitting issues, they should be addressed in regulatory negotiations.
Permit requirements for technical analysis of compliance measures should
also be carefully considered during regulatory negotiations. Compliance ana-
lytical issues in permits might address certain size fractions in the soil, establish
sampling methods or techniques, and even specify sample preparation. The
sample type (grab or composite), sampling frequency, sample preparation meth-
ods, and specific analytical methods can also be set as permit conditions with
the oversight regulatory agency. For example, the state of Washington sets
compliance based on total analysis of <2 mm soil fractions, whereas federal
guidance sets compliance at the <60 mm soil fraction size.
3.13 Performance Measures
Site restoration is conducted to reduce health risks to human beings and to
reduce the impact on the environment. Cleiarly, the simplest and most expe-
dient action, would be to excavate the site aiid ship the soil to a well-designed
landfill to isolate the contaminants from human contact and the environment
in perpetuity. Soil washing is only undertaken to reduce the volume of con-
taminated materials and, thereby, lower the costs of shipping and disposal.
The primary measure of performance is the decontamination efficiency of
the system as measured by the maximum cost-effective return of clean mate-
rial to the excavation site. As long as additional volume reduction can be
accomplished at less expense than the avoided costs of disposal, more treat-
ment steps are warranted. Further, it must tie realized in planning that
"clean" material does not mean only those particles that individually meet
3.61
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Design Development
release criteria. The matrix returned to the excavation can contain some
substantially contaminated media, so long as an assay of a representative
sample is within agreed limits. Understanding this concept is essential to
monitoring system performance.
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The work plan negotiated with regulators and disseminated to the public
should clearly state the restoration goals negotiated in the record of decision
(ROD) for the site. This should include both a risk-based allowable level of
residual contamination in the material to be returned to the site and the
planned percentage of material to be returned to the site. The latter value
should reflect the estimated recoverable fraction based on treatability stud-
ies, less some contingency calculated for process efficiencies expected from
full-scale equipment. These values become the benchmarks against which
performance is measured throughout the job.
Performance data may also focus on any module internal to the process,
such as hydrocyclone separation efficiency or suspended solids removal
across the clarifier. These data are also used to monitor operations and in
that context are discussed in Section 4.4.
Sampling methodology should be explained in the work plan. This in-
cludes how representative samples will be obtained, the frequency of sam-
pling, and me maximum allowable deviation in any product sample or dura-
tion of off-specification operation. Sampling of process effluents and residu-
als should also be delineated. Effluent data will be evaluated against any
required permits or negotiated limits in the ROD. Residuals data will be
used to satisfy the shipping and disposal waste-acceptance criteria. All ana-
lytical work for quality assurance (Q A) samples should be performed using
US EPA-approved SW-846 methods and/or other standardized techniques
approved by regulators prior to commencing operations.
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An independent analytical service will probably be used to perform QA
checks, but it is essential that operating personnel take similar samples in the
same manner to ensure that QA data accurately reflect process and perfor-
mance monitoring data. This is particularly important where field determi-
nations are not absolute and actual contaminant levels must be inferred from
field data. For example, field measurement of metals by x-ray fluorescence
must be periodically checked against wet chemical measurements with total
sample digestion to ensure that the field determination is representative.
3.62
i
' ; : : ; : i
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Chapter 3
3.14 Design Checklist
The following is a design checklist to assist in conceptual planning for a
soil washing project.
1. Soil Physical Characteristics
Site topology and geology
Particle-size distribution curve
Percentage of oversize, sand, and fines fractions
Organic carbon
Mineralogy
Plasticity index and moisture
2. Contaminant Occurrence
Free, particle, coating, bound, and/or soluble
Relative contribution by fraction
Chemistry of contaminant with respect to washing solution
3. Level of Treatment |
Simple separation
Simple separation plus treatment of the sand fraction
Simple separation plus treatment of the sand and fines
fractions
Special case
4. Site Conditions
Site access
Facilities layout
Excavation plan and staging plan
Pad and containment requirements
Utilities access
i
Building requirements
Supporting facilities (offices, decontamination areas)
i
3.63
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Design Development
5. Treatment Standards
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" Key contaminants
Required concentrations
1 ' i
Handling and use of "clean" material
6. Schedule
Mobilization to site
Site preparation period
Obtaining approvals
Waste processing period
Required throughput to meet schedule
7. Treatability Study Information
Soil matrix/contaminant eyaluation
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Conceptual process-flow diagram
Conceptual engineering
3.64
III n; .illinium .Hi i !"<;.._,,! j,,iii||ji||iiigni_,'L LJM.ii.i.i.Li'L-.j.-.^-j
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Chapter 4
IMPLEMENTATION AND OPERATION
4.1 Implementation
|
The implementation of a soil washing project must consider the services
to be provided, the procurement methods, and the method of contracting.
-
4.1.1 Procurement Methods j
4.1.1.1 Traditional
The traditional procurement method involves bids submitted by contractors
and approved by the client for each stage of the remediation process. In the
case of soil washing, the approach would be to prepare a bidable work package
for each stage of the work, such as the treatability study, the design, the pilot
study, site preparation, excavation, treatment operations, and residual disposal
The advantage of this method is that the lowest possible price can be obtained
through the multiple competitive steps, but at major disadvantage is for the loss
of coordination among the inter-related activities. It requires a very strong
client Project Manager to make this approach successful.
4.1.1.2 Design-Build/Operate
In some soil washing projects, the work is divided into two main parts.
One contractor will perform the treatability study, prepare the design, and
manufacture the plant. After delivering the; plant to the site, erecting it, and
providing some basic training, that contractor leaves the site. A second con-
tractor will take over the plant, usually on a project lease/rental basis. This
contractor will operate the plant, complete the project, and turn the plant
back over to the original manufacturer upon completion. The advantage of
4.1
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Implementation and Operation
this approach is that a dependable contractor, not normally in the soil wash-
ing business, can access a treatment unit at a reasonably low cost while not
incurring the cost of developing that capability internally. Of course, a ma-
jor disadvantage is that the plant provider is not included in the loop of re-
sponsibility to ensure that the project is successful and that any major design
or manufacturing flaws are corrected. The operating contractor may have
received some basic training on the plant's operations, but is not prepared to
perform sophisticated troubleshooting when required. The apparent cost of
this method is low, but a high risk is present if processing problems arise
because such problems could seriously jeopardize the project.
4.1.1.3 Design-Build-Construct-Operate
Another approach to soil washing projects is to select one contractor who
will perform all activities related to the soil remediation, including the treat-
ability study, the design, the pilot study, treatment operations, residuals dis-
posal, and site closure. The advantage of this approach is that all the respon-
sibilities reside in one contractor, and there is single source accountability
from the client's perspective. All corrective actions needed to make the
project work are in the contractor's control. The disadvantages to this
method include the problems that will arise if a contractor cannot perform or
does not have the financial resources to correct problems. Unless care is
taken by the client up front, there is the possibility that the price of this ap-
proach may not appear to be the most competitive, although in the long-run
it may be.
4.1.1.4 Contract Operations
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The contract operations method might logically be used in a large govern-
ment remedial project where the duration of the project extends beyond the
normal operating life of the capital equipment. In such a case, it might make
sense for the government to design, procure, and construct a plant under one
contract, and then to solicit a second contract for the long-term operations.
There still remains the concern that the operations contractor may not be
properly keyed into the development of the plant, but this potential problem
is likely to diminish over the long-term operations period. Additionally, the
client (the government in this example) may choose to require an extended
carryover period during which the plant design contractor is available to
assist with operations.
4.2
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Chapter 4
4.1.2 Contract Terms
i
Contracts for soil washing may be awarded under different terms, each
having their own advantages and disadvantages.
4.1.2.1 Lump Sum Contract
A lump sum contract is a fixed price arrangement for a specified piece of
work. This contracting vehicle is generally one that clients like because their
risk is capped for the specified work. No extras are recoverable by the con-
tractor. If the work costs more than projected, the contractor is responsible,
and if the work costs less, the contractor besnefits. Under this approach, there
is no difficult accounting required to check and discuss each element of cost
during performance of the work since there; is only one real measure, com-
pleting the work. For a soil washing project, the lump sum is usually de-
fined by a quantity of soil to be treated. Appropriate language is normally
included in the contract to allow for renegotiation if changed site conditions
result in more work.
I '
4.1.2.2 Cost Plus Fixed Fee l
The cost plus fixed fee (CPFF) contract allows all costs of the project to
be reimbursed to the contractor, but that contractor will receive only a fixed
amount of "fee" (i.e., profit) no matter what the ultimate scope of the
project. This approach requires the client to check each and every cost ele-
ment of the project, a process that often turns adversarial as site changes and
difficulties arise. The client may, in the end, obtain the lowest apparent
price, but at the cost of the heavy involvement of a client project manage-
ment team. A variation of this contracting arrangement is a cost plus award
fee in which the fee is based on performance.
l
4.1.2.3 Unit Price Contract '.
A unit price contract may appear similar to a fixed price or lump sum
contract in that it contains a total price based on estimated quantities. How-
ever, the actual cost is based on a unit price: per ton for soil processed. With
this arrangement it is essential that all terms be defined, including:
unit basis tons of soil excavated, screened, fed to the plant, or
produced; >
\
weight basis dry weight or wet weight; and
4.3
-------
Implementation and Operation.
method of measurement a calibrated weigh cell, approximated
by a number of bucket loads, or some other.
Generally, the contractor will want to treat the most tons possible while
the client will want the least amount treated for a given unit price.
4.1.3 Preferred Combination
For most soil washing projects, the preferred combination of procurement
method and contract terms is the design-build-construct-operate procurement
method (see Section 4.1.1.3) using a lump sum contract. The responsibility
to perform is placed clearly on the shoulders of the contractor. The contrac-
tpr must plan and manage all activities required within the scope of services.
The work can be controlled and measure9by the client with a reasonable
level of effort. The project can still be bid competitively. A well thought-out
request for proposals can define the cost elements so that the resulting lump-
sum pricing is fair.
4.2 Start-up Procedures
4.2.1 startup ' ; ; ' " \"" "' ' .;';'"." ' '"'.,"; ^ri
Start-up activities generally commence after the soil washing plant is
erected and clean process water is introduced into the tanks to prepare for
operations. Start-up activities will generally consist of three key steps:
1. Running the System on Clean Water. 6nce all of the process
tanks have been filled and mechanical and electrical continuity
checks have been made, the system will be started up to check
for leaks, mechanical misconnections, and proper flow through
the tanks, cells, and treatment units. This run will usually be
completed in one day.
2. Running the System on Clean Soil Once the mechanical and
plant integrity issues are checked, the next step is to introduce
solids into the plant. It is advisable to conduct this phase of the
startup with clean soil so that if there are any problems, they can
4.4
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Chapter 4
be handled without the concern of contamination. A clean soil
stockpile can easily be prepared at the project site. The volume
of clean soil prepared should be enough to load .the cells and
treatment units to the normal siolids operating levels, plus the
additional amount required to produce some products (oversize,
sand, and sludge cake). This phase of the startup is intended to
confirm the ability to move solids though the plant and to test
solids handling systems such as the conveyors, screens, and de-
watering equipment. Some problems may be encountered at this
stage and some troubleshooting should be expected. This phase
can generally be completed within 1 to 3 days.
3. Introducing Contaminated Soil. Once the plant has been checked
using clean soil and any necessary corrective actions have been
completed to the satisfaction of the team, the plant is deemed
ready to accept contaminated soil. At this stage, the plant should
still be considered to be in a start-up condition and should be
operated carefully. A stockpile of contaminated test soil will be
prepared by the contractor. The plant must be loaded to levels
that are sufficient to allow the various treatment units to be oper-
ated. In most cases, the clean soil introduced in the earlier stage
does not need to be removed from the system prior to this step.
The start-up test run is performed to confirm that the plant is operating and
can produce products that meet the designated treatment standards. This is not
the period when the plant is optimized or when extensive testing should be
demanded This is merely the first step in preparing the plant to perform.
4.2.2 Performance Optimization
Once the plant has been confirmed to bfe operating properly, the operators
will optimize the plant's performance.
4.2.2.1 Field Pilot Study
A field pilot study can be performed with the full-scale process plant before
commencement of the actual remediation. This field pilot study is an excellent
opportunity to see the plant in full operation and affirmatively set the stage for
normal, steady-state operations. The field pilot test is conducted on the con-
taminated soil that will be fed to the plant during normal operations. A
4.5
-------
Implementation an/d Operation
stockpile of material will be prepared by the contractor for this purpose. For an
"average" project, about 5% of the mass to be treated could be considered an
appropriate feed amount for this field pilot study. The field pilot study is not
intended'.to determine if the technology works (that should have been confirmed
long ago), but rather to provide actual field operating and cost data and to assure
the client and the regulators that the plant is up and performing, and can be
reasonably expected to meet the requirements of the various work plans and
regulatory requirements cost effectively.
During the field pilot study, the contractor will operate the plant in the
mariner specified in the operations plans. Known feed material will be
loaded into the machine, and the specified products and residuals will be
produced. This phase will involve more product sampling than is usually
required. With these data, the contractor can confirm the attainment of the
treatment standards and calculate the process mass balances, leading to cal-
culation of the volume reduction attained and the ability to track the mass of
soil and contaminants through the system.
I
4.2.2.2 Process Adjustments and Modifications
During the field pilot study, it is natural to expect that adjustments and
minor modifications will be required and will be implemented. Some of the
variables that may be addressed during this stage include:
> adjusting the feed rate;
changing the decking on selected mechanical screens;
modifying the sand/fines separation cut point;
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ป adjusting the residence times in key treatment units;
adjusting the dosage rate of chemicals in key treatment units;
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tuning overflow rates in clarifiers; and
i
improving the dewatering performance of essential units.
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4.2.3 Process Validation
After all objectives of the field pilot study have been accomplished, it is
expected that the contractor will be given approval to operate at a specified
throughput level and under the requirements of the normal operations plan
by the cognizant regulatory authority(ies).
i
.: ' ' f': "-1 .:" ' ' ' ' - 4.6 " ' ;i''' ' ' ' ' ^
-------
Chapter 4
Systems Integrity. A successful pilot study demonstrates the integrity of
the systems within the soil washing plant. Any new problems or upsets will
be handled as part of a corrective response measure or as part of the normal
maintenance program.
Product and Residual Confirmation. Information about the quality of
plant products and residuals will be collected under a detailed sampling and
analysis plan. The plan will define the location, frequency, and method of
collecting the samples required. At a minimum, sampling will include the
feed material, products (process oversize iind sand), residual materials that
may require off-site disposal, any recoverable products, and any required
intermediate products.
Process Economic Confirmation. Operations data from the field pilot
study will enable the contractor to confirm anticipated full-scale costs.
The real measure of quality will be the concentrations of target contami-
nants in the products. Soil washing is rather unique in the sense that it is a
"fail-safe" system. That is, if something goes wrong, it does not result in a
precipitous action that jeopardizes the equipment or personnel. The main
failure that can occur is that the soil does not meet the quality standards.
This can be easily measured. Soil that does not meet the standards can be
staged outside the plant while the plant problems corrected and then reintro-
duced for further treatment.
4.3 Operations Practices
The soil washing process will be managed and controlled by the contrac-
tor responsible for the operations. The most indicative measure of a process
under control is one that produces products of steady, compliant quality. The
client, engineer, or regulator can quickly obtain a good assessment of the
process by looking at the sampling log data on product quality and by re-
viewing the manifests that record the quality and quantity of residuals
shipped off-site for disposal.
No products are allowed to be placed back on the site as clean material
until the approved analytical data confirms the attainment of the treatment
4.7
-------
Implementation and Operation
standards, and, not until the area of excavation has been sampled and
cleared. " ' , , ' " \
4.3.1 Process Control
The process will be controlled by a number of intermediate parameters
determined by the contract and consistent with the information they will
require in order to make products attaining the treatment standards.
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4.3.2 Process Upsets
Every process will have unplanned upsets. These upsets may range from
minor occurrences that can be easily corrected during the normal course of
treatment to catastrophic occurrences that may require long-term plant shut-
down and even the replacement of portions of the system. Every good con-
tractor has a contingency plan for these events, but not all of the possible
upset situations can be foreseen.
"Normal" upsets are handled by having a good understanding of an engi-
neered plant along with well-trained operators, a reasonable supply of spare
parts, and a technology/equipment backup resource that can be called upon
during unusual circumstances.
,n" . ,!,]'" " ' ' ! ' ." ,
4.3.3 Maintenance Requirements
Plant maintenance activities fall into two primary categories: preventive
maintenance and corrective maintenance.
Preventive maintenance is performed on a schedule and includes planned
upkeep activities such as lubrication, checking pumps, and cleaning out
chemical dosing units. This work will include activities scheduled to be
performed weekly, monthly, quarterly, or annually, based upon the manufac-
turers' recommendations. A preventive maintenance plan is a normal part of
a soil washing plant operations plan. Preventive maintenance is often per-
formed on Saturday morning if the plant is operating five days a week with
one shift per day.
Corrective maintenance is the activity that must be undertaken immedi-
ately to correct some fault with the plant. Problems requiring corrective
maintenance may include an overflowing tank, a blocked pump, a blinded
screen, or a loss of flow or chemical supply. Most of these problems are
4.8
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Chapter 4
common and easy to fix. Good operators and a reasonable supply of spare
parts can usually take care of these problems. Naturally, some events may
cause serious damage or plant outages that will require skill on the part of
the plant operations team and use of the backup resources. Since every pos-
sible problem cannot really be anticipated, Ihe client or the regulator must
have confidence in the contractor's ability to understand the technology and
manage it.
4.3.4 Safety Practices
Good safety practices are essential in the operation and management of a
soil washing treatment system. Every soil washing operation should be
performed with an assigned, full-time Health and Safety Officer (HASO).
The ultimate responsibility for safety belongs to the contractor (although it is
common for clients to also take responsibility for safety issues). Authority
for safety performance, checking, and corrective actions is delegated to the
HASO. Every remediation operation is required to have a detailed health
and safety plan (HASP) as discussed in Section 3.8.3. The HASP will out-
line the responsibilities of all team members, specify personal protective
equipment requirements, define respiratory protection requirements, identify
routes to the nearest medical facilities, and define the requirements for safety
meetings and periodic review of the ongoing operation.
4.3.5 Laboratory Requirements
Laboratory analyses are indispensable to operational control and it can be
enhanced if those analyses which can be quickly performed are selected as
primary control indicators. Even with on-site facilities, certain laboratory
tests take days to perform and this time lag can be detrimental to ongoing
operations. If the laboratory is off-site or not under the control of the site
operator, additional delays are possible. The time required for properly per-
formed (with applicable QA/QC) analyses must be incorporated in the oper-
ating plans. Additionally, provisions must be made for re-treating soils
which do not comply with treatment requirements determined by confirma-
tory laboratory testing.
4.9
-------
Implementation and Operation
4.4 Operations Monitoring
System reliability and performance are the results of insightful design,
good planning, observant and creative operators, and proper instrumentation.
This is not necessarily the order of importance. The key point is that opera-
tions monitoring involves more than collecting data. Even in cases where a
system is weU designed, project management: has planned for all foreseeable
circumstances and all process indicators are well within normal ranges, a
system walk-through by a good operator may identify an off-normal condi-
tion before it is manifested as a significant process upset. The following
paragraphs identify some of the measurements that can be taken to charac-
terize a process and help operating personnel diagnose problems and im-
' ' M M ' prove efficiency.
As described in Section 3.13, the true indicator of performance is cost-
effective volume reduction. Thorough characterization by testing and other
monitoring can allow calculation of the maximum amount of material that
can be returned to the excavation for any allowable residual level. The ex-
tent to which the process approaches this ideal state is limited by the effec-
tiveness of physical segregation of the more contaminated particle sizes. For
non-extractive processes, the residuals are the contaminated fines. For sys-
tems that use chemical extractants to solubilize contaminants, physical seg-
regation is just as important, but process residuals can be further reduced by
concentrating the contaminants hi process solutions.
|.'' ' (I': r . ', lii'O'.'V'^ : , . .- - , :,, , :.., v -;' ,j;| 'J.,,' ,, ',.. * , -. ' ,;.!'. |;?,
4.4.1 Process and Instrument Diagram
Each process module will have some characteristic measure of operating
efficiency from which the total process efficiency is calculated. Based on
the feed characterization, treatabih'ty studies, and experience, a detailed pro-
cess and instrument drawing (P&ID) can be developed. Initially, the P&lD
will act as a guide to evaluate operating data at any point in the system. As
the job proceeds and soils from the site are processed, actual data can be
used to update the P&ID. Keeping an up-to-date P&ID in the control room
for operator reference is good practice and will pay for itself many times
over. Ideally, the values taken when the system seems to "run itself should
be noted in detail, so that when an upset must be analyzed, engineers have a
basis for comparison in the operating log.
Jf'U:111
I"1I!|H ,i| i , I
4.10
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Chapter 4
4.4.2 Mass Balances
If the amount or the quality of the clean product soil fraction deviates
significantly from the expected values, soil mass balance data from each
module will provide a starting point to determine where the losses are occur-
ring. Internal QA samples will also be necessary if the contaminant or par-
ticle-size distributions are not consistent. Product quality can deteriorate if
the separation of contaminated fines is inadequate. Even with good separa-
tion, product quality can deteriorate if the contaminant distribution changes
and more contamination is present in the larger size fractions. If the equip-
ment is working well, the mass balance of the contamination could be the
problem. Analytical data will be required to separate the two phenomena.
Without the proper data, operations personnel could spend a great deal of
time analyzing the wrong questions.
4.4.3 Representative Samples
Representative samples of product piles are essential. There will always
be a certain amount of contaminant carryover. For example, a few pure
metal fragments or contaminant conglomerates can probably be found in the
"clean" gravel pile at any given time. This is expected. As long as sample
results are within acceptable limits, the system may continue to run without
question. However, undetected damage to a screen or poor operation can
lead to additional contamination and spot-check QA samples collected
through routine procedures may not detect the problem for some time.
Well-intentioned sampling personnel, accustomed to seeing unusual
particles may not realize the number has increased. Analytical person-
nel may not include a metal fragment in the analysis because they, too,
may get accustomed to separating out an occasional fragment. The
problem may require visual inspection of the piles or counting the num-
ber of metal fragments in a randomly taken bucket of product. The sam-
pling protocol must be designed to capture representative features of
each type of product at the site.
ฃ
4.4.4 Parametric Testing
Most parametric testing is done during the treatability tests, but there are
always differences in full-scale equipment that will warrant additional
4.11
-------
Implementation and Operation
< ' 1 " "> ! '
testing. If time permits, some of the module operating conditions can be
varied to maximize performance and throughput.
11 ' ' '' ','' ";;,'' -! ' '! !' " '" , ' ' ,'" ", !,',"' !''
111 "i "i
4.4.4.1 Screens
Vibrating screens can be varied in frequency and amplitude to minimize
the required residence time and maximize size separation. The water flow
rate to sprays can be varied to provide adequate dispersion of particles and
prevent clay from agglomerating and blinding the screen.
i ; , , _;;'; .1 ] .. 1 ;i .' ,;'; , . ' | .
4.4.4.2 Cyclones and Classifiers
Cyclones and classifiers operate under physical principles that are essen-
tially pure cause and effect. Within an allowable range of flow rate and par-
ticle loading, they will provide continuous, reliable separation. The operat-
ing envelope can be defined and documented for operators, and performance
should thereafter be monitored by checking flow meters.
4.4.4.3 Attrition Scrubbing
,','', 1 ; !;T , ,,'ir'"' , "i , ; '- I ;: , " , ,; ,'!", ,'! ''"''"'"'
Attrition scrubber operation can be modified by altering impeller speed
and residence time. These parameters can be well tested in the laboratory,
but there is the potential to improve the cleaning of sand and small gravel by
varying the initial setpoints modestly. Analytical data and possibly a stereo-
microscope will be necessary to determine improvements in cleaning.
4.4.4.4 Flotation
Efficiently floating specific fractions (eig.,' organic matter, clay fines, or
specific mineral types) are the result of selecting the correct residence time,
air injection rate, mixing speed, and a variety of possible chemical additives
to enhance, suppress, or modify the attraction of gas bubbles to the desired
particles. Chemical additives will be selected based on laboratory experi-
ments, but the other variables can be optimized in the field.
] , , ., _
4.4.4.5 Settling
Clarifiers operate on the basis of adequate residence time. However,
flocculants added in the proper amount and well mixed into the slurry may
markedly reduce the residence time required for settling. The mixing step is
important and should not be ignored. The flocculant must contact the
4.12
-------
Chapter 4
particles to be settled. The chemical injection rate should be varied to mini-
mize settling time which may be the critical limiting step in the process.
It is noted that changes in the waste stiream composition which can occur
during processing may require a change in the type or amount of flocculant
to ensure effective settling.
i
4.4.4.6 Water Treatment
Metal removal and/or recovery is typically accomplished by pH adjust-
ment to cause precipitation, settling, and filtration. Each of these steps can
be optimized to maximize the cost-effectiveness of the process. The opti-
mum pH for precipitation of one metal may conflict with that of another.
Whether they are both optimized and done sequentially, or a compromise
condition is used to remove the most metal attainable in one step, will
depend on the water quality requirements of the process and the dis-
charge. Settling time, type and duration of filtration, and use of
flocculants are also parameters that cam be varied to reduce costs while
meeting water quality criteria.
Ion exchange may be used to recover valuable components or radionu-
clides. The type of regenerant chemical, ithe concentration, and regeneration
cycle time will all affect the performance of the system. The manufacturer's
recommended practice is always a good place to start, but unique field con-
ditions may require testing to optimize the cost-effectiveness of the system.
Regenerant chemical usage and operating time between regeneration cycles
are good parameters to monitor to optimize operation.
Treatment for organic contamination and extractant conditioning may
have several more variables to control. Examples may include temperature,
pH, residence time, and chemical additives, such as defoaming and emul-
sion-breaking agents. , '
4.4.4.7 Solids Dewatering and Drying
After settling, the resultant sludge sluny is filtered to remove free liquids.
A continuous belt vacuum filter or pressure filter may be affected by the
flocculant used and the water content leaving the clarifier, as well as the
mechanical variables of the equipment itself. While removal of free liquids
is the primary goal to meet disposal criteria, drying the sludge thoroughly
will reduce weight, which reduces shipping and disposal costs. Facilitating
4.13
-------
Implementation and Operation
additionalair drying after the filtering operation by turning or spreading the
sludge may have a significant impact on cost.
11 '!
4.5 Qualify Assurance and Quality Control
Quality assurance (QA) and quality control (QC) are critical to the suc-
cessful operation of a soil washing facility. They ensure the validity of data
needed for process control and for evaluating system performance, determin-
ing the appropriate disposition of residue, and establishing regulatory com-
pliance. QA/QC procedures will help to ensure that representative samples
are collected, that introduction of contaminants during sampling and analysis
is minimized, and that high-quality analytical data are produced. Without
proper procedures, samples may become contaminated during collection,
preservation, handling, storage, or transport to the laboratory. At the labora-
tory, additional opportunities for contamination arise during storage, in the
preparation and handling stages, and in the analytical process itself. Unreli-
able, contaminated, or unrepresentative samples waste money and can jeop-
ardize project success. Valid and useful results answer a question or provide
a basis on which a decision can be made.
Because they are interrelated, QA/QC are typically thought of as one
entity, but they do have different scopes. QA is a system of activities that
assures the producer or user of a product or service that defined standards of
quality are met. QC differs in that it is an overall system of activities that
controls the quality of a product or service so that it meets the needs of us-
ers. QC comprises the internal, day-to-day activities, such as QC check
samples, spikes, etc., that are performed to control and assess me quality of
measurements. QA, oh the other hand, is the management system that en-
sures an effective QC system is in place and working as intended.
111 I1!,*" , .. ,, ," i,_,__. , ..j JL; j. . >] [' !ซ i ,;!; i;i i .;'; :,i,:", I /w
The QA/QC program must be carefully planned In accordance with data-
gathering needs to ensure that data will be of sufficient quality. The intended
use of data measurements should be addressed explicitly in the sample plan-
ning process and reiterated in the analytical planning process. Careful plan-
ning is also required to ensure'that sample's" adequately reflect the population
being studied. QA/QC planning should define the problem and analytical
4.14
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Chapter 4
program well enough so that the intended results can be achieved efficiently
and reliably.
4.5.1 Sample Collection Issues
i
The objective in collecting samples for analysis is to obtain a small and
informative portion of the population being investigated. If samples, indi-
vidually and collectively, cannot provide the required information, they are
seldom worth the time and expense of analysis.
All sampling methods should be reviewed. If questions arise during the
review, additional confirmatory analyses maiy be needed, possibly using
other methods.
Each sample should be reproducible. Variations caused by different op-
erators, equipment, location, time, and conditions should be minimized. As
part of the QA/QC program, sampling methods should be verified and vali-
dated to help ensure reproducibility. Verification is the general process used
to decide whether a sampling method is capable of producing accurate and
reliable data. Validation is an experimental process involving external cor-
roboration by other laboratories, methods, or reference materials to evaluate
the suitability of methodology for a particular application.
4.5.2 Laboratory QA/QC Specifics
A laboratory QA/QC program is an essential part of a sound management
system. It should be used to prevent, detect, and correct problems in the
measurement process and/or to demonstrate attainment of statistical control.
The objective of QA/QC programs is to control analytical measurement
errors at levels acceptable to the data user and to assure that the analytical
results have a high probability of acceptable quality.
There are several key steps in establishing QA/QC:
planning to define acceptable error rates;
quality control to establish error rates at acceptable levels;
quality assessment to verify that the analytical process is operat-
ing within acceptable limits; and
reporting and auditing data quality within the laboratory.
4.15
-------
il ""
"" *'-. I::1!1"!!11
I-: i
1 :
ri: I
Implementation and Operation
ili:!'::,!,
f Si
"I ; ,
Each laboratory should have an independent person who reports on and
carries put the QA/QC program. All QA/QC programs should be docu-
mented, for example, in a manual or program plan better known as a Quality
Assurance Program Plan (QAPP): QA/QC procedures help ensure valid
analytical data. The plan documents the specific steps for implementing the
sampling and analytical procedures which are designed to provide reliable
data The plan also describes the procedure for auditing QA/QC implemen-
tation to ensure that the work and documentation are being conducted in
accordance with established procedures, the elements of an acceptable QA/
QC program include:
development of, and strict adherence to, principles of good labo-
ratory practice;
consistent use of standard operating procedures; and
establishment of, and adherence to, carefully-designed protocols
for specific measurement programs.
111 . i
4.5.2.1 Controls/Audits
, ' , , " i,,! ^ ,, ,;! ' ' |! i^t i!' ^'T ,,,,!'! ', Ml ' M ,|,'.iin, |!ป .1, ,^1 \: |!|{ , i|i|,|,|,'|,,, | r , ' 'njil , :ii).,i..' '," JlLiW,!,!'1
A QA/QC system includes consistent use of qualified personnel, reliable
and well-maintained equipment, appropriate calibrations and standards, and
the oversight of all operations by management and senior personnel.
Audits should be a feature of all QA/QC programs. Three kinds of audii
are usually performed; these are systems, performance, and data audits.
A systems audit is qualitative and should be made at appropriate intervals
to assure that all aspects of the QA program are operative. Performance
audits, in which a laboratory is evaluated based on the analyses of perfor-
mance evaluation samples, are quantitative. They also provide valuable
quality assessment information: In data audits, a few samples are randomly
selected from a project. During a data audit, all documentation, data entry,
calculations, instrument calibrations, data transcription, and report formats
are checked for accuracy and conformance to the project QA/QC plan from
the time of receipt through the final report.
4.52.2 Samples for Controls/Audits
QC samples are the primary means of estimating intra-laboratory variabil-
ity. Current US EPA laboratory requirements generally specify a uniform
4.16
i
-------
Chapter4
schedule of QA/QC sample analyses for chemical parameters. All laborato-
ries that analyze samples for regulatory compliance must analyze one dupli-
cate sample and one matrix spike sample for every 20 samples. A problem
with this method is that the schedule may include too few QA/QC samples
to control for analytical error. Other controlling standards may have differ-
ent QA/QC requirements.
.
4.5.3 Data Quality Criteria for Soil Washing
.
4.5.3.1 Types of Data
Field screening data are the lowest quality, but yield the most rapid re-
sults. They can be used for health and safety monitoring to rapidly deter-
mine the potential human exposure to contaminants and particulates during
soil washing site operations. Field data assist the operations team in daily
process control and in preliminary performance evaluation.
Laboratory analyses are designed to identify and quantify compounds in
samples of various matrices. This level of analysis typically provides data to
support site characterizations, environmental monitoring, confirmation of
field data, engineering studies, and, in specific cases, risk assessments. Re-
sults of the laboratory analyses will provide information on the soil washing
system's ability to meet soil performance and cleanup goals. RCRA analy-
ses can also be used to characterize the site media as nonhazardous or haz-
ardous before, during, and after soil processing.
i
4.5.3.2 Data Quality Parameters
In the soil washing process, QA/QC provides the ability to confirm that
the sampling and analytical activities are being performed correctly and that
the data can be used confidently to make remediation decisions. Five char-
acteristics of data quality are used to assess the data:
precision,
accuracy,
completeness,
representativeness, and
comparability. j
4.17
-------
Implementation and Operation
Precision is a measure of agreement among individual measurements of
the same property under similar conditions. It is expressed in terms of rela-
tive percent difference (RPD) between duplicates, or in terms of the standard
deviation when three or more replicate analyses are performed. Compared
to other remediation processes, typical soil washing objectives for the RPD
between field duplicates range between 20 to 50% for soil samples and 10 to
20% for water samples.
Accuracy is the degree of agreement between a measurement and an ac-
cepted reference or true value. Accuracy will be determined in the labora-
tory through the use of matrix spikes, surrogates, laboratory method blanks,
and laboratory control samples. Trip and field blanks are also analyzed to
ensure that samples have not been cross-contaminated and that concentra-
tions measured at the laboratory represent the concentrations in the field
samples. Results measure the preparation accuracy and serve as a check on
any sample contamination that may be encountered during sample prepara-
tion. Statistical control is the first requirement that must be met before accu-
"1" ' ' '" " ' ' '. ป' ll .... , r |
racy can be assessed.
Completeness is a measure of the amount of valid data obtained com-
pared to the amount expected to be collected under normal correct con-
ditions. Data points may not be valid and may be eliminated if a sample
exceeds holding time, did not meet the acceptance criteria, or was bro-
ken or contaminated. A completeness criteria of around 80% is normal
for a soil washing process.
," ' ':,'. " : , .,,',. .. - ,ri; .| . ! ',: ""I i- ;:!, i
Representativeness expresses the degree to which data accurately and
precisely represent a characteristic of a data population, process condition,
sampling point, or an environment. Representativeness is a qualitative pa-
rameter of the sampling program. It is highly dependent on proper sample
collection techniques which can be evaluated through the analysis of field
duplicate samples and comparison with previous data sets.
Comparability is a qualitative parameter expressing the confidence with
which one data set can be compared to another.
4.18
-------
Chapter 5
CASE HISTORIES
Cose 7 Soil Washing Treatability Test at
100-DR-1 Operable Unit at the Hanford
Site, Richland, Washington
General Site Information !
Name: 100-DR-l Operable Unit
Location: U.S. Department of Energy's Hanford Site,
Richland, Washington
Owner:
U.S. Department of Energy
P.O. Box 550
Richland, WA 99352
Owner Contact:
Julie Erickson
U.S. Department of Energy
P.O. Box 550
Richland, WA 99352
(509) 376-3603
5.1
-------
I1 IlliMilnll! I'1' ' '"Hi,. ill1 111'ill!' ' "lull-, 'l ' 'i' 'ป n , ' ': i ,r n, .' V '
llY f!.( IL '''' |Y; ",;,''"" ';'!':')!' Case Histories
i, i.'i iiiiir iii/K < r.,,1,1 i11. lull
'B '
W!ii> ; "Y l ' i!'! :.j - ;,; i;-. , ,. ' Y'' | ... :< <*
Remediation Contractors(s) (Environmental Restoration
v"'.Y ^*4." ' "44 4,: Contractor [ERC] Team): ' " 4.4.!
;!!;;*'"_, '' "" "n Y " , : Bechtel Hanford, Inc. ;
li? "Y!: ; ' ;; '4. ' ': 450 Hills Street ' '
?*' ' ': v , ;.--: ' ' Richland, WA 99352 ' ''
:|! '!:*' ':'!'4' ,, ". ' ,, -.! ': ' " ' (509)372-9041 " ' ' " '""
i, 3W i , 'I '', K, , - .' ;,? .11 P v ,5,,,, ,. . , ,, , i-,, , ,; -, |... ,:, , ,,:-ni ,,
;;4"4; ri'; ' 'j.'' " '.\ ^ , ] CH2M HILL Hanford, Inc. '' '4 j
isiii.rl " ' :;4 , ,,,' 4,,-4 ^i- ' : RO.BOX'ISIO '" '' ' '' ' "
"::: " :" " :" ' ":" ": ' '" Richland,WA99352
, ; .' ,Y ":,:1 Y Y (509) 375-9424 ; ; |
>'. ; " "^ '. IT Hanford, Inc. "" " '
! ::,:,,:': :"; ,,,,; ;' . ' : P.O.Box 1099 ,' | '
Richland, WA 99352
,, !; ,..,. ,., , ,,, . , ,(509)372-9419 ^ " ^ ^ [
'-' :4 :.'''.''.'" "Y': , TMA Hanford, Inc. ' '' ";" :""":;'"!'' "; ':' ;" "f" ;
450 Hills Street
Richland, WA 99352
I , j Y" PS ,, T ;,<', , ., ,,(509)372-9241 , '
1' "! !' ! '" ' ', ' ' 4 4 4": 44 ,'4 ' '""'44"
Regulatory Factors
li .i,,;;11: , ,. IK, ij , ; , i , ' , . "i' 11
Authority
Hanford Federal Facility Agreement and Consent Order (fri-Party Agree-
ment between DOE, US EPA, and State of Washington) and CERCL A
1 | "'"'/ ' lป , i ' l li ",'i1 ' ' '' "i ; ' , L , "'i ,!, ' I'. .i 'j ''Mil',,, """' ' ' ',. ,f' ,,.J| !'' Ill
Requirements/Cleanup Goals
Cleanup levels established after completion of the test. Cleanup level is
15 mrem/yr (cumulative total of all radionuclides summed together) above
background. For metals, State of Washington MTCA B levels are the
cleanup standard (chromium VI, 400 mg/kg).
" ' , ' ', ; ,;,; ; ",,,j , , ;;; ';",';;;
Results
,. ,,':,!' ',!'' : ' ' ' , :,' ', ' " : ' ' Wซ. ' ' '' i ' :' II I l|,'! 'i' " 11 , ป , I "I
Cleanup goals for metals were met after treatment.
5.2
"ill V '1 ' Iliili'1, 'I" I,'
-------
Chapter 5
Exposure in clean treated soils was 15.3 mrem/yr without taking
background into consideration.
Operation
Type (Cleanup Type)
Treatability test
Period
January 9-12,1995
Waste Characteristics
Source
Nuclear reactor liquid effluent discharge trench
Contaminants) j
Radionuclides:
cesium-137, cobalt-60, europium-152 metals; and
chromium.
i
Highest concentrations in feed soils:
cesium-137 (22.7 pCi/g), cobalt-60 (0.67 pCi/g), europium-152
(8.63 pCi/g), chromium (9.8 mgAg).
Exposure using average feed concentrations:
72.0 mrem/yr without background (residential scenario).
Type of Media Treated j
I
Sands and gravels:
average moisture content in feed soils is 7%.
Quantity of Media Treated
92.5 tonne (102 ton) of contaminated sand and gravels (99% less than 6 in.)
5.3
-------
'III ,
"ii,"''
"J! ,11
Case Histories
Technology
Description
Excavation and stockpiling:
I : " ' ,, : 'i'i , , ..... | ...... ,ป, |,i|i,j,,' I '!!"',i .' ,i ! , .. i ".ซ .....
excavation of overburden arid contaminated soils with a track
mounted excavator (backhoe).
Soil washing system:
design capacity: 9 tonne/hr (10 ton/hr); operating capacity this
test: 4.5 tonne/to (5 ton/hr);
maximum treatable size: 6 in. minus;
water-based system;
coarse screening by grizzly with 6 in. bar spacing;
wet Screening of 2 mm to 6 in. ;
I , ,. . , ,
attrition scrubbing of 0.25 mm to 2 mm sand;
": ' " '> ..... ]> ' ...... ''"< -
dewatering screen drys 0.25 mm to 2 mm sand;
. fmes pumped to a clarifier for thickening of minus 6.25 mmsand
and silt and clarification of process water;
i ป, : ..... ": ..... , , ii" is, ,,i ,ซ, "lii ..... E, ,;;!' , i.|< ;,i .'i| i . , HI ฅ,ซ' ' iv , " f i i
rotary drum filter dewaters minus 0.25 mm sludge; and
filter cake stored in LS A boxes for disposal.
L ' .. '.,
Significance
First pilot-scale test on 100 Area soils at the Hanford Site. Confirms
bench-scale tests that soil washing is technically feasible in the 100 Area.
Included test of real time monitoring for radionuclides on conveyors.
i
Cost Data
Total cost (disposal not included) approximately $2.3 million
(DOE-RL 1995).
5.4
-------
Chapter 5
Project Description
The 100 Area of the Hanford Site contains nine inactive nuclear reac-
tors that were operated to produce fissionable material. Each water-
cooled reactor situated along the southern bank of the Columbia River
has been shutdown and is currently being evaluated for decommission-
ing. Waste streams that were generated during the operation of these
reactors were disposed of into trenches, and cribs, resulting in substantial
volumes of contaminated soils. i
Soils from the 116-D-1B trench in the 100-DR-l Operable Unit were
selected for bench-scale tests. These soils were expected to be representative
of most liquid effluent waste sites. Results of the bench-scale tests indicated
that soil washing may be a viable volume! reduction treatment in the 100
Area, so a pilot-scale soil washing treatability test was performed.
The plant was designed, built and operated by the ERG team between
September 1994 and January 1995. A total of 327 tonne (360 ton) of uncon-
taminated overburden and 92.5 tonne (102 ton) of contaminated soils were
excavated. Approximately 73 tonne (80 ton) of the uncontaminated soils
were processed during December 1994 and early January 1995 as part of the
shakedown operations. The contaminated soils (all 92.5 tonne [102 ton])
were processed between January 9 and January 12, 1995.
Of the 92.5 tonne (102 ton) of contaminated soils processed, 85% by
weight were returned to the excavation as clean and 15% by weight is stored
in lined LSA boxes awaiting disposal. During the test 238 samples were
taken and received various types of analysis. The uncontaminated soils were
replaced back into the top of the excavation. The report, Soil Washing Pilot
Plant Treatability Test for the 100-DR-l Operable Unit (DOE/RL-95-46)
(DOE-RL 1995), documenting the operations and test results was issued
September 29, 1995.
All information for this case history as well as further details are con-
tained in Soil Washing Pilot Plant Treatability Test for the 100-DR-l Oper-
able Unit (DOE/RL-95-46)(DOE-RL 1995) which has been approved for
public release and issued in its final form.
5.5
-------
Case Histories
Case 2 Soil WdshingTreatability Study
for Operable Unit 5, U.S. Department of
Energy, fernald Environmental
Management Project, Cincinnati, Ohio
General Site Information
Name: Fernald Environmental Management Project (FEMP)
Location: Butler/Hamilton County, 20 miles Northwest of
1 ( ,'i ' , .' , ' , !,, ' i I -I! ,' >"' .... ',' . .. , \ i", ' ' , : M
Cincinnati, Ohio
Owner: U.S. Department of Energy
Owner Contact:
.Pill '" :., ' !ii. ' vi. - ','!!'' -'I. ' is,,. ,!,ป. ' A,;1"1:,- . ii . '" i. , i1 ,H| .,n "u - ,
Michael Krstich
Hour Daniel Fernald
25 Merchant Street
Cincinnati, OH 45246
(513) 648-6231 or 648-3000
!!'. I , ....'.' .... . .!....(
Remediation Contractors(s):
Primary Contractor Hour Daniel Fernald,
Support Engineering it Corporation
Regulatory Factors
iin'i . ,.. , ' "!|IC j.'; : . :"" .'.,' ' ' '
. . !i " ; , ;*! ^'' Authority ' ' ' '"
III1 ' ' ;: H ' : ":i ""';l CERCLA'
ROD Date: 11/95
Requirements/Cleanup Goals
Cleanup level for total uranium was preliminary targeted at 35 pCi/g (ca.
equal to 50 mg/kg'1 total uranium) as outlined in NRC guidelines (1981).
5.6
-------
Chapter 5
Results
Bench-scale results indicated that a physicochemical process incorporat-
ing sequential extraction steps using Na,,CO3/NaHCO3 and dilute H2SO4
could approach the 50 mg/kg'1 targeted cleanup level. Pilot-scale results
showed a 90% reduction in total uranium mass for nearly 75% of the initial
soil mass and final total uranium concentrations that were less than 40 mg/
kg"1. This process was extremely aggressive, resulted in process residues of
nearly 40% (approximately 25% soils and 15% chemicals added) that re-
quired disposal, and was assessed to be not a cost-effective engineered ap-
proach to treatment of soils at the FEMP.
Operation
Type
Bench-scale and pilot-scale treatability testing
Period
Period of operation:
bench-scale treatability test: April 1992 thru May 1993; and
pilot-scale treatability test (Batch operation): May 1993 thru
August 1993.
Waste Characteristics
Source
Surface soils (2 locations):
Plant 1 Pad Area; and
Incinerator Area.
Contaminant(s)
Target analyte Uranium
5.7
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Case Histories
'J-:-l|.; Type'of'Media Treated
Soils (ca. 20% sand, 60% silt, and 20% clay for fraction less than 2 mm)
Quantity of Media treated
Bench-scale treatability test: 50-250 g per tfeathienf sample
Pilot-scale treatability test (Batch operation): 2sOb-250kg
(441-55 lib) per batch
Technology
ii ,i ' ,mii i if1
Description
Soil washing
Bench-scale testing:
physical separation; and
chemical extraction.
Pilot-scate testing:
physicochemical treatment; and
batch operated system (ca. 250 kg [551 lb] per batch).
Pilot-plant soil washing system equipment:
148.7 m2 (1,600 ft2), bilevel arrangement;
trommel screen with high pressure sprayer (4.75 mm screen);
vibrating duel-screen deck (2 mm and 0.3 mm screens);
horizonal duel-scroll centrifuge (0.02 mm particle-size separation
& de watering);
attrition scmbber (0.02-4.75 mm particle attritioning)(Na2CO3/
NaHCO3extractant);
chemical extraction reactor vessel (H2SO4extractant);
. processing tanks (1,893 L [500 gal] PVC tanks for interim stor-
age); and
plate and frame filter press (dewatering precipitate from spent
extractant).
5.8
-------
Chapter 5
Significance
One of the first large-scale soil washing treatability testing efforts for
removing radionuclides (uranium) from soils at a DOE site. Incorporated
both extensive bench-scale testing (chemical extraction and physical separa-
tion) and subsequent pilot-scale testing and system design (physicochemical
process).
Cost Data
Total cost for design, construction and operation of the soil washing pilot
plant was approximately $1,000,000. Additional costs were incurred during
the initial bench-scale testing and subsequent engineering evaluation and
conceptual design.
Project Description
Soil washing was identified as a viable treatment process option for
remediating soil at the FEMP Environmental Management Project (FEMP).
Little information relative to the specific application and potential effective-
ness of the soil washing process exists that applies to the types of soil at the
FEMP. To properly evaluate this process option in conjunction with the
ongoing FEMP Remedial Investigation/!feasibility Study (RI/FS), a treatabil-
ity testing program was necessary to provide a foundation for a detailed
technical evaluation of the viability of the process. In August 1991, efforts
were initiated to develop a work plan and experimental design for investigat-
ing the effectiveness of soil washing on FEMP soil. In August 1992, the
final Treatability Study Work Plan for Operable Unit 5: Soil Washing (DOE
1992) was issued.
Bench-scale testing was initiated by IT Corporation in April 1992 and
completed in May 1993. Equipment procurment, skid-mounting, and instal-
lation on-site at the FEMP occured during the period between November
1992 and May 1993. Pilot-plant operations were conducted during the May
through August 1993 time frame. The pilot-plant soil washing system was
design to operate in batch mode with a processing rate of approximately 250
kg/week (55 Ib/week).
A summary of the findings of this extensive testing established a baseline
understanding of the FEMP soil-contaminant matrix, as well as the potential
effectiveness of soil washing on FEMP soil. The primary considerations when
5.9
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Case Histories
determining the effectiveness of soil washing for decontaminating FEMP soil
must be premised with an understanding of the diversity of soil types, contami-
nant concentrations, and trie resulting soil/contaminant matrices. The effective-
ness of soil washing with respect to a reduction in residual uranium mass and
mobility, and!this extrapolation to the concept of volume reduction, were evalu-
ated based on me results from mese extensive bench-and pilot-scale studies.
. : r" :'.: ;i ' , ' '. .. ;;: ' VL iv.1 " ' , ' ; , .;
Based on a summary of me finding from trench-and pilot-scale testing, a
hybrid soil washing system was engineered which emphased a sequential ex-
traction process that incorporated a carbonate based reagent as a primary extrac-
tant followed by a sulfuric acid based secondary extraction process used on an
as-need basis. Using a conservative estimate, extrapolated from pilot-scale
results, for the potential effectiveness of a hybrid soil washing system for all of
FEMP soils, it is estimated that greater than 90% of the soil can be treated to a
residual total uranium concentration of 100 mg/kg'1 or less with a mobility of
less than 1 mg/Lr1 total uranium established through TCLP testing.
>'i Illi'S 1 , !!, ! , I'll " " '!': , I ' , , ;"!.' . ' j ' !' .. . ' ,!'"
Cose 3 Soil Washing at The U.S. Army
Corp. of Engineers, Saginaw River Site,
Essexville, Michigan
;i
ii
;":"": ' ;" '"''".' General Site Information ' ""' ' ' |"" '"' '' '
Name: Saginaw River PCB Contaminated Sediment Site
I
Location: Essexville, Michigan
I Ifi'iiji,, ,,> , ; ,; ,;nl , L i!; ,,:,,!, '" ,, I'll! ' fh ". i ,':,' ,', I ,ป. ' !' ,ป ' i!" "!,i ' ," I I III ll " 'i, ,ป.
Owner: U.S. Environmental Protection Agency, Great Lakes
National Program Office (GLNPO)
Owner Contact:
Dr. James Galloway
U.S. Army Corp. of Engineers
Detroit District
477 Michigan Avenue
Detroit, MI 48226
(313) 226-2056
5.10
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Chapter 5
Remediation Contractors(s):
Richard P. Traver
Bergmann USA
1550 Airport Road
Gallatin,TN 37066
(615)230-2217
(615) 452-5525 (FAX)
Regulatory Factors
!
Authority
Assessment and Remediation of Contaminated Sediments (ARCS)
Requirements/Cleanup Goals !
CERCLA cleanup levels: !
Clean coarse fraction (>45 microns);
PCB's 0.188 mg/kg;
Al 760 mg/kg;
Ba 5.85 mg/kg;
Ca 13,900 mg/kg;
Cu 7.1 mg/kg; and
Pb 12.0 mg/kg.
Results
Cleanup goals were achieved for PCBs and 5 heavy metals. As reported
in the GLNPO Applications and Analysis report entitled Pilot-Scale Demon-
stration of Sediment Washing for the Treatment ofSaginaw River Sediments,
EPA 905-R94-019, the Bergmann Sediment Washing System performed with
a 100% on-line duty factor.
'5.11
-------
ili'l ' I1 '"' F
.' ' '. i, :" tsnil!!!1, i:ปi ilii/lTiffl
Case Histories
H!
"'"Ink
1 ; '!!',
.:: ฅ,'!
',; [. ' '"" ',ฃ
I!;1,,,,;,: ilii,;1;,
fJjS ;||i'"'>y
: I:;,/: ii,:;.
Operation
Type
Full-scale field demonstration
' ''-is; *# I- Period
* .r
nil I:
SI
October 1991 to June 1992
Waste Characteristics
Source
Contaminated commercial waterway sediments from dredging operations
Contaminant(s)
Organics:
polychlorinated biphenyl; and
i ', ,; .. ,' '''.. ; ,. r> '. ,.:;ซ;' < ':', ' li**''' i": ,|<
maximum concentration in feed 5-7 mg/kg.
Metals:
Al 27,000 mg/kg;
Ba 182 mg/kg;
Ca 96,000 mg/kg;
Cu 87 mg/kg; and
.* Pb 70 mg/kg.
Type of Media Treated
Sediment
Quantity of Media Treated
454 tonne (500 ton) of slack dried sediments
Moisture content of approximately 21%
pH of approximately 6.5
S', !fe
5.12
-------
Chapter 5
Technology
i -
Description
Coarse material and debris scalping with computer belt scale
Soil washing system:
five components deagglomeration, screening, dense media
separation, attrition scrubbing, flocculation/sedimentation; rated
feed capacity 4.9-9 tonne/hr (5-10 ton/hr);
screening multiple screens; coarse static grizzly scalping
screen (>2 in.) Wet screening of <2 in. materials with five screen-
ing at 45 micron (325 mesh);
separation hydrocyclones separate coarse- and fine-grained
materials;
dense media separation removal of contaminated light organic
humic materials (leaves, twigs, roots, etc.) by upward rising wa-
ter/elutriation;
attrition scrubbing high energy surface-to-surface particle
contacting for release and separation of contaminated clay mate-
rial from coarse (3/8 in. by 45 micron) material fractions; and
flocculation/sedimentation - polymer addition for removal of -
45 micron material within inclined plate clarifier.
Significance
Army Corp. of Engineers ARC's full- scale sediment remediation demon-
stration aboard self-contained support barge performed 2 miles off shore.
System evaluated under US EPA Superf und Innovative Technology Evalua-
tion Program. ;
;
Cost Data
As reported in the US EPA SITE Applications and Analysis report en-
titled, Pilot-Scale Demonstration of Sediment Washing for the Treatment of
Saginaw River Sediments, EPA 905-R94-019, the Bergmann Sediment
Washing System reported that estimated cost of soils/sediment washing op-
erations were as follows (see Table 5.3.1).
5.13
-------
'UlM'lJI'l ' II"I'"!'"!!
Case Histories
' ";' , Table 5.3.1 V" ,"" '. .' .".
Costs in $/ton for Operation of Various Sizes of
Bergmann USA/Soil Sediment Washing Systems"
hil; ' ,;
ป' I!1"!'1 , .!,!"If i
"
Treatment Rate
Total Treatment Time
' ' '
5 ton/hr 15 ton/hr 25 ton/hr 100 ton/hr
1 year 2 years 3 years 5 years
Site Facility Preparation Costs
Including Excavation
(Excluding Excavation)
Permitting & Regulatory Costs
Equipment Costs
Startup & Fixed Costs
Labor Costs
Supplies Costs
Consumables Costs
Effluent Treatment & Disposal Costs
Residuals & Waste Shipping, Handling & Transport
Costs
Analytical Costs
Facility Modifications, Repair & Replacment Costs
Site Restoration Costs
Total Costs
(Total Costs Excluding Excavation)
$20.00 $17.85 $15.78 $14.74
($0.25) ($0.09) ($0.06) ($0.03)
$12.73
$28.89
$58.10
$7.92
$4.10
$8.51
$19.64
" sjft&fV,,'
$6.67
.I
$2.72
$7.29
$16.37
'_" $11.62""
$5.42
$2.50
$5.04
$11.12
$3.67
$4.12
$2.35
I $3.81 $0.95
I
$0.54 $0.36 $0.30 $0.17
$151.32 "
1.46 $63.08 $42.16
($131.57) ($63.71) ($4736) ($27-44)
All costs estimated at 1993 prices
1, Hi Iff '"',,'"' " 'illk ',i'i ih, ii, |
Project Description
f
' " ' ' , ' ' ''',
Bergmann USA was invited to present an overview on river and harbor
sediment treatment technology to the joint US EPA and Army Corps of En-
gineers' ARCS (Assessment and Remediation of Contaminated Sediments)
Workgroup in March 1991. Bergmann was contracted by Jim Galloway,
ACOE-Detroit for Pilot Sediment \Vashing Demonstration on the Saginaw
River Project. In-house, bench-scale treatability evaluations were per-
formed, followed by the design and fabrication of a 4.5-9 tonne/day (5-10
ton/hr) pilot-scale Bergmann USA field demonstration sediment washing
5.14
-------
Chapter 5
plant to effectively separate contaminated fines from coarse fractions of river
dredge sediments. This plant was placed into operation in October 1991 a
mile and a half off shore aboard a 37 m by 10 m (120 ft by 33 ft) Army
Corps of Engineers dredge support barge for the processing of approxi-
mately 454 tonne (500 ton) of PCB contaminated spoil.
Preliminary results indicate a reduction of 91% of the initial PCB concen-
tration with only 0.2 mg/kg of PCBs remaining in the "clean" coarse +74
micron (200 mesh) fraction. The -74 micron fines were enriched to! a level
of 14 mg/kg PCBs, and the humic fraction (leaves, twigs, roots, grasses, etc.)
contained 24 mg/kg of PCBs. These materials were scheduled for biodegra-
dation during the Spring/Summer of 1992.
Working with Jack Hubbard of the US EPA Hazardous Waste Engineering
Research Laboratory in Cincinnati, this Bergmann USA system was evalu-
ated by the Superfund Innovative Technology Evaluation (SITE) Program in
May/June 1992 by SAIC, Inc. Preliminary analytical test results were avail-
able in July 1992 to be followed by the Technology Evaluation Report and
Applications Analysis Report in 1995.
This 9 tonne/hr (10 ton/hr) Bergmann USA plant processed approxi-
mately 181 tonne (200 ton) of PCB contaminated dredge sediments prior to
winterization. An additional 272 tonne (300 ton) of material was washed
during the May/June 1992 evaluation period.
Case 4 Soil Washing and
Hydrometallurgical Lead Extraction,
tongue Pointe Garrison, Montreal,
Quebec, Canada
General Site Information
Name: Longue Pointe Garrison, National Defence Canada
Location: East Montreal, Quebec, Canada
5.15
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Case Histories
!*
Vendor:
Bruce E. Holbein
Tallon Metal Technologies, Inc.
1961 Cohen
1 :' |:lปn .' ,! ' ! ', ' '""ป,:!, ?'' ,' i ":" " '" ', '' " "' '' ,. Jll'Jli i: ! ซ: "i1 i ''
Ville Saint-Laurent, Quebec
Canada H4R2N7
(514)335-0057
(514)335-8279 (FAX)
Point of Contact:
Sylvain Lavoie
-..- I""";! DCC Site Engineer
Canadian Forces Base Montreal
St-Hubert, Quebec
Canada J3Y5T4
(514)462-7400
Project Operating Company:
Tallon Environment Inc.
6769 Notre Dame Est
Montreal East, Quebec
Canada H1N3R9
(514)252-0735
SIC Code: 4593
Regulatory Factors
Authority
Department of National Defence
Defence Construction Canada (DCC)
Environment Canada
Supply and Services Canada
Ministry of Environment & Fauna (Quebec)
5,16
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Chapter 5
Requirements/Cleanup Goals
Environment Canada guidelines:
less than 900 g/t lead (industrial); and
less than 500 g/t lead (residential)
Results
i . - .
Cleanup objectives are to return soil that meets either industrial or residential
cleanup guidelines of Environment Canada and the Ministry of Environment
and Fauna, Quebec. These guidelines are less than 900 ppm total lead for in-
dustrial reuse soils and 500 ppm total lead for residential reuse soils. Lead
concentration is determined by XRF and/or AA analyses. Air and water emis-
sions are monitored to conform to environmental specifications.
Operation
Type
Full-scale cleanup
Period
September 1994 to May 1996
Treatment Operation: June 1995 to May 1996
Waste Characteristics
i
Source
Lead smelter stack emissions
Lead battery recycling operations
I
Contaminant(s)
Lead
Scrap metal
Diesel fuel
5.17
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Case Histories
; '!' It! I O. .'VMi;,]
I ;
'Jl !ซ|" ' I I,
Hi 'I'1:!"' i , ' [" ;, Hit"
: i, :: T , ,,im
1
Type of Media Treated
High clay soil (approximately 60% clay)
Classified as hazardous soil (fails TCLP test)
Lead content up to 50,000 g/t
80% of soil lead <10 pn
Moisture content approximately 20%
pH between 8 and 9
Quantity of Media Treated
149,685 tonne (165,000 ton) excavated
_ .1 'iti "' ! T ,,i - ' ,"',' , ./, /I1' . " ; ,.' S; II.1: < ,,
Technology
Description
Pretreatment: coarse scrubber, magnetic and gravity separations, size
classification.
Lead Extraction: conditioning of minus 0.0394 in. size fraction, chemi-
cal extraction of lead, recovery of lead concentrate, recovery of cleaned fine
soil fraction.
Site Restoration: return as backfill of 97% of clean soil, landscaping and
'::: , . , .. ' " ' ,,/ " .: !'<' " L1-!" ;, >. ,!,,., n ;,. , %,. .: . r ;P ,... ,.
seeding.
Significance
The Longue Pointe Project is significant as it represents the first full-
scale integration of conventional soil, washing with chemical extraction of
metal from fine fractions of the soil. This enhanced process provides total
treatment of the soil and reuse of 97% of the original soil after treatment.
The high clay nature of the soil (>50%) and multiple contaminant sources
permitted demonstrating of materials handling, dissagregation, physical
separation, chemical extraction of metals arid fine soil dewatermg methods
at industrial scale. The project is also demonstrating that clean soil prod-
ucts are produced which are returnable to the site or could be beneficially
used off-site.
5.18
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Chapter 5
Lead contamination to hazardous (fails TCLP leach) levels was a conse-
quence of industrial activities at the site at separate times. Lead smelting
was conducted at the site until the early 1970's, producing a plume of aerial
emissions of lead (60 to 65% of contaminated soil). In the late 1970's and
early 1980's a second phase of contamination resulted from lead battery
crushing and lead metal recovery operations. Metallic lead as well as battery
solutions containing lead were spilled on the site.
Cost Data
The total project cost is US $18.8 million which includes the treatment
cost for 116,120 tonne (128,000 ton) of hazardous soil, as well as excava-
tion, civil work, and the construction of fixed facilities for the military base.
Average treatment charge on a dry tonne (dry ton) basis is approximately US
$123 ($112). This compares favorably wilth restricted landfill disposal at a
cost of $148 to $192/tonne ($135 to $175/ton).
Project Description
The Longue Pointe Project included selective excavation of contaminated
soil (hazardous classification) for temporary storage in a containment cell
adjacent to the site designated for the treatment plant. The quantity of soil
and time constraints, required a plant with the capacity to process 726 tonne/
day (800 ton/day). Independently monitored bench-scale and pilot-plant
treatability studies demonstrating treatment effectiveness were prerequisites
to a competitive commercial bid. In addition to full treatment, the project
also included civil work and infrastructure construction. Detailed engineer-
ing design, procurement and construction of the treatment plant commenced
in July 1994 and the plant was commissioned in May 1995, The project
specifications require that the site be landscaped and seeded at the conclu-
sion of treatment.
5.19
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Case Histories
...... '~~
(TCAAP), Site F, New Brighton, Minnesota
General Site Information
Name: Twin Cities Army Ammunition Plant (TCAAP), Site F
;..-' ' . ., ;!, ' ., ..;-; ;;:,;!: .:;,,;,, jv: i;\ j',f ;:.. I. :" !' .. ;; ' i -,
Location: New Brighton, Minnesota
M .'ป">ป' ' ซ>- , -, ' i";:;:; ' 3-"; Owner Contact:
'!. I", I, M, ,
' " ..... Martin McCleeiy ' ..... ...... ""' '" ...... ,",
Environmental Engineer
U.S. Army
Twin Cities Army Ammunition Plant
.;.'. ..... ! SMCTC-CO" ........ ' ' ' .......... "' "
New Brighton, MN 55 1 12
(612)633-2308
Remediation Contractors(s):
-';"-': William E. Fristad ^ . .' '""'"' '' "
'"''' "' ........ COGNIS, Inc.
2331CircadianWay
Santa Rosa, CA 95407
(707) 575-7155
Regulatory Factors
Authority
CERCLAandRCRA
PRP Lead
5.20
-------
Chapter 5
Requirements/Cleanup Goals
Soil cleanup levels for 8 metals:
Sb (4mg/kg);
Cd (4mg/kg);
Cr (lOOmg/kg);
Cu (80mg/kg);
Pb (300mg/kg);
Hg (0.3mg/kg);
Ni (45 mg/kg); and
Ag (5 mg/kg).
Results
Cleanup goals were met for all 8 metals.
All soil remained at TCAAP.
i
No residuals were disposed of in a hazardious waste landfill.
Operation
Type
Full-scale cleanup
Period
September 1993 to July 1995
I
Waste Characteristics
i
i
Source I
i
Ammunition burning/burial
5.21
-------
''it! """I:
i! it
(I 111
Case Histories
HI fill it 'liC*1' ,'S ;"" . J!"
Contaminantฎ
... ' Y - ' : ^" -.; Tr: :*:'.: >.;: . *."^\
Metals:
antimony, cadmium, chromium, copper, nickel, silver, lead, mer-
cury; and
highest metals concentrations in soil lead (86,000 nig/kg),
copper (>iOO,000 mg/kg), mercury (20 mg/kg).
Type of Media Treated
Soil and ammunition
Quantity of Media Treated
18,597 tonne (20,500 ton) of soil
Moisture content of approximately 15%
pH of approximately 7.0
i
>272 tonne (300 ton) of ordnance
i' " "' '.._.. .
Technology
i
Description
Soil washing/soil leaching
Materials handling:
selective excavation of metals-contaminated soil using visual
inspection and x-ray fluorescence.
Soil washing system:
four components deagglomeration, screening, sand and fines
separation, density separation;
jj
screening oversize screen (>1?4 in.);
separation elutriation separates coarse and fine-grained mate-
rials; and
'' {' ' " '
density separationremoves metallic particles.
Lin In. lS"l , v hi.;'"".ii!
5.22
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Chapter 5
Soil leaching system:
leaching both sands and fines leached; and
metal recovery all leached metals were recovered in elemental
form and recycled.
Significance ;
First full-scale application of soil washing and soil leaching. Contami-
nant metals were removed, recovered, and recycled. All soil fractions were
treated.
Cost Data
Total cost of $5,000,000 (including excavation, health & safety, ordnance
removal, and treatment).
Project Description
COGNIS' TERRAMET soil leaching and Bescorp's soil washing systems
have been successfully combined to remediate an ammunition test burn area
at the Twin Cities Army Ammunition Plant (TCAAP), New Brighton, Min-
nesota. TCAAP is an industrial complex covering 2,370 acres in metropoli-
tan Minneapolis, St. Paul that manufactured primarily small caliber rifle
ammunition. Off-spec ordnance material and ordnance supplies were buried
at Site F, the area remediated in this project. The cleanup is the first in the
country to successfully combine these two technologies, and it offers a per-
manent solution to heavy metal remediation,, Over 18,144 tonne (20,000
ton) of soil were treated in the project. The cleaned soil remained on-site,
and the heavy metal contaminants were removed, recovered, and recycled.
Eight heavy metals were removed from the contaminated soil achieving the
very stringent cleanup criteria of < 175 ppm for residual lead and achieving
background concentrations for seven other project metals (antimony, cad-
mium, chromium, copper, mercury, nickel, and silver). Initial contaminant
levels were measured as high as 86,000 ppm lead and 100,000 ppm copper,
with average concentrations over 1,600 ppm each. Final average values for
residual copper was 46 ppm and lead was 71 ppm. In addition, both live and
spent ordnance (>272 tonne [300 ton]) were removed in the soil treatment
plant to meet the cleanup criteria. By combining soil washing and leaching,
COGNIS and Bescorp were able to assemble a process which effectively
5.23
-------
'":: aran -t UT : i
in * : W,T;' ,. : ' i;
Case Histories
.'Jill'
" i ป i
I"
Will!* ' "lli
all the soil fractions so that all soil material could be returned on-site,
^,,:' .'..no wastewater was genera^edrandu'tne"heavy metals were recovered and
";:.'."'',"""'recycled. No'hazardous ^'^'j^^'l'^fiir'disposal was generated
during the entire remedial operation.
6 Soil Washing at The Toronto
Harbour Commissioners, Contaminated
Soil Recycling Facility
," ! "I1 si",: " f1' . ; ".:-.. . ' ,: ' .;,:!v-<,- \\ I ซ ...*.>..;., : : -.:v.J:
General Site Information
Name: Toronto Harbour Commissioners Cherry Street, contaminated
soil recycling facility
Location:
Toronto Harbour Commissioners
Cherry Street
Toronto, Ontario
Canada
Owner Contact:
Dennis Lang
Toronto Harbour Commissioners
60 Harbour Street
Toronto, Ontario M5J 1B7 Canada
(416)865-2047
Remediation Contractors^):
Richard P. Traver
Bergmann USA
1550 Airport Road
Gailatin, TN 37066
(615)230-2217
(615) 452-5525 (FAX)
5.24
nil n i n i n ii i i nil in n nun 11 n i in in i .;;; f !iiHiiii!i'ii,i:'i * \,PA '\ ป, iiiii^iiiiiiiiij
I, i!"' ,iiinihhii!i', iJiiiiiiiimiJiii'j'1 "iitji ,''iii:iii,iiiiiiiiri!iiii,iii!'l it
-------
Chapter 5
Regulatory Factors
Authority
Toronto Harbour Commissioners & Ontario Ministry of the Environment
Requirements/Cleanup Goals
Toronto Harbour & Ontario ministry on the environment standards:
BTEX 2.6mg/kg;
naphthalene 4.1 mg/kg;
benzo(a)pyrene <0.2 mg/kg;
TPH 1,200 mg/kg; and
Pb 37 mg/kg.
Results
As per the Toronto Harbour Commissioners designated criteria, cleanup
goals were achieved for TPH (Oil & Grease) and copper, nickel, lead, zinc,
benzene, toluene, xylene, naphthalene, phenathrene, pyrene, benzo(a)pyrene,
chrysene, benzo(b&k)fluoranthene, dibenzo(a)anthracene.
Operation
Type
Full-scale field demonstration
Period
January 1991 to September 1991
Waste Characteristics
Source
Contaminated soil from industrial properties and contaminated sediment
from the Toronto Harbour. j
5.25
-------
ill'llilHi!! : <1 "1! . ,,
11111 111 11111
Case Histories
* \ r
'' IIP!! ", "'ill!! il''!,l
Ill I I
\:
Contaminants)
Organics:
BTEX 69 mg/kg;
naphthalene 17.25 mg/kg;
benzo(a)pyrene 2.75 mg/kg;
TPH 37,833 mg/kg; and
Pb 149 mg/kg.
Type of Media Treated
Soil and sediments
Quantity of Media Treated
4,536 tonne (5,000 ton) of contaminated soil and harbor sediments from 5
different industrial hazardous waste sites.
Technology
Description
Materials handling
Coarse material and debris scalping with computer belt scale
Soil washing system:
six components deagglomeration, screening, dense media
separation, attrition scrubbing, flocculation/sedimentation; rated
feed capacity 4.5-9 tonne/hr (5-10 ton/lir);
screening multiple screens; coarse static grizzly scalping
scredn (>2 in.) wet screening of <2 in. materials with five screen-
ing at 45 microns (325 mesh);
separation hydrocyclones separate coarse- and fine-grained
materials;
i' ' I !"|nl|'i:' ,,' , Jl'ljij ,, ii"'ij!!, ',|'li| i , , ;,ii ,,, !' , , i ,, * '!,;;, ' ji'1'1 ' iijjjj, ', " " ,j "i'1 j *!' |j,i iii'j,,1 |,ป "i1 ,t ,n i1 i'i, i iji , , .jj, ,!,, ,, .I"";', ซy "'i||:i|||| ,< 'laiTH
dense media separation removal of contaminated light organic
humic materials (leaves, twigs, roots, etc.) by upward rising wa-
ter/elutriation;
5.26
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Chapter 5
attrition scrubbing high energy surface-to-surface particle
contacting for release and separation of contaminated clay mate-
rial from coarse (3/8 in. by 45 micron) material fractions;
flocculation/sedimentation polymer addition for removal of -
45 micron material within inclined plate clarifier; and
deep cone thickener for sludge densification to 35% solids for
further treatment.
i
i
Significance |-
Full-scale demonstration of a totally integrated soils recycling facility
incorporating soils washing, acid extraction/electro winning of heavy metals,
and bio slurry reactors for organic contaminant destruction.
Cost Data j
As reported in the report prepared by The Toronto Harbour Commission-
ers and Zenon Environmental Laboratories entitled, The Toronto Harbour
Commissioners'Soil Recycling Demonstration Project, presented November
9,1992 at the Cleanup of Contaminated Sites Conference in Toronto,
Ontario, no cost of operation information was presented for the operation of
the Bergmann Soil/Sediment Washing System. Bergmann's estimated cost
for an 91 tonne/hr (100 ton/hr) or 272,155 tonne/yr (300,000 ton/yr) reme-
dial project of the Toronto Harbour front area is approximately $27/tonne
($25/ton)(excluding excavation and residuals management).
Project Description
Bergmann USA was contracted by the Toronto Harbour Commission for the
installation of a 4.5-9 tonne/hr (5-10 ton/hr) piilot-scale soils washing system for
the demonstration of volumetric remedial operations coupled with an innovative
metal extraction and biodegradation technologies for the treatment of the -74
micron fines fractions. With the receipt of permits from the Ontario Ministry on
the Environment, Bergmann USA transported and erected in-place a complete
modularized plant on the site. The system was completely shrouded by a Rubb
Fabric Building, a tube heat exchanger was installed raising the temperature of
process operations wash water to approximately 27-32ฐC (80-90ฐF). Canadian
weather/temperature permitting, the demonstration commenced on January 6,
1992, and was operated for an initial 28 week jperiod.
5.27
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'if '!
Case Histories
'i j *: ' --^
,1; Ik!"
.IT! !;. , "I'1 .j
in. KIM i i. i
,,:,,
1!
The Bergmann USA soils washing plant processed approximately 2,722
tonne (3,000 ton) of heavy metal, PNA and petroleum hydrocarbon contami-
nated soil materials. The Wastewater Treatment Technology Centre of the
Ontario Ministry of me Environmental had TBergmaririprocess approximately
454 tonne (500 ton) of contaminated dredge spoil from the Toronto Harbour.
A total of 3 175 tonne (3,500 ton) of material was scheduled for Bergmann
to provide effective volumetric red"uclon: The US EPA HWERL SITE
evaluated the Bergmann plant at the Toronto project location in April 1992.
The final t|S EPA report was released inApril 1993 and can be obtained by
contacting Ine National Technical Information Service at (703) 487-4600
and requesting EPA Report No. 540/AR-93/517, Toronto Harbour Commis-
sioner (THC) Soil Recycle Treatment Train.
Following the completion of the Canadian demonstration project it is
anticipated that a full-scale plant would then be designed for installation for
a three year, 77 tonne/hr (85 ton/hr) or 272,155 tonne/yr (300,000 ton/yr)
remedial project of the Toronto Harbour front area.
Case 7 Soil Washing of Lead and
Grease ''
General Site Information
Name: Prudhoe Bay, Alaska
Location: Dead Horse, Alaska
i
.' ,p:!jv "": ........... , ,,; . " ,; ; ':,: ..... " '" ,: '. i-.;. '," , '. :* ,' ' '- ;.!,:,, | .'..'
Owner Contact:
MerebadNadem
State of Alaska
Department of Environmental Conservation
.i.:'' FairfeankSy AK ''_' ' \ J" J"^' " \' '"J
(907)451-2360
5.28
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Chapter 5
Remediation Contractors(s):
TVffiS,Inc.
(Tuboscope Vetco International Environmental Services, Inc.)
2835 Holmes Rd
P.O. Box 808
Houston, TX 77001
Regulatory Factors
Authority
i
State of Alaska Department of Environmental Conservation
Requirements/Cleanup Goals
Total lead <500 ppm, TCLP lead <5 ppm, 1PPH by
US EPA 8020 <500 ppm
.
Results
Cleanup goals met for 97% of the soil.
Average total lead 224 ppm, TCLP lead 2 ppm, TPH 207 ppm.
Fines (3% of mass) with TCLP lead <5 ppni were stabilized, and
landfilled.
Cleanup achieved in less than 2 months in remote location with very diffi-
cult supply problems.
Operation
TVpe
Full-scale cleanup
Period
July to September 1992
5.29
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Case Histories
''4 I' i, 111
I "I !!ป pp illr li
1111 : ,i i1'! !' M1 :i iii-,11 (I
if,
Waste Characteristics
Source
Pipe dope which had contaminated the gravel pad of an oil field pipe
inspection building when the building burned.
ContaminantCs)
Lead (total 3,330 ppm, TCLP 37 ppm) and grease (5,530 ppm)
Type of Media Treated
Gravel, sand and glacial till
Quantity of Media Treated
4,587m3 (6,000 yd3)
2%<200mesh
Technology
. "" !i ,. M. , ' ' , i1 '. i ',, i j ,. ,, f '" :, I .'',.,,'ir ,. jDirlih,
Description
Soil wash with counter-current scouring in augers with 27 atm (400 psi),
99"C (210ฐF) weakly acidic solution. Fines acid extracted, water settled and
recycled processing rate 9 tonne/hr (10 ton/hr) with 98 L/min (26 gal/
min) water.
Significance
Remediate a RCRA metal in a remote and fragile Arctic wilderness. This
was the first large-scale soil washing project in the United States in which a
RCRA metal was remediated. The project was completed in a very remote
location at less than 15-20% of the cost of alternative remediation methods.
' nii ' "'!'' ii.",,,!, ,,' ' ,. i.',,ซ,( ,ซ."'
Cost Data
Total project cost $1.2 MM, included equipment construction, 1991 pilot,
1992 mobilization, demobilization, and stabilization of nonhazardous fines.
5.30
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Chapter 5
Project Description
Tuboscope Vetco International operates oil field pipe inspection buildings
in 45 countries. In 1991 their inspection facility at Dead Horse, Alaska serv-
ing a portion of the Prudhoe Bay oil field burned down. The pad of the
building was found to be contaminated with lead and grease used for prepar-
ing pipe, some of which may have melted during the fire. The cost of alter-
native cleanup technologies, especially transport and burial in the lower 48
states was excessive, so TVI re-engineered sand and gravel washing augers
to melt and scour contaminants from the soil.
Equipment was designed and built in Houston, Texas, and mobilized to
the site in 1992 for a pilot. In 1992 the full-scale project was conducted.
Case 8 Soil Washing at the Gustavus,
Alaska Airport Site
General Site Information
Name: Gustavus Airport
Location: Gustavus, AK (99812)
Owner Contact:
Claire Jaeger
Chief, Construction Branch, USACOE, Alaska District
Richardson Resident Office
Anchorage, AK 99506-0898
(907) 384-7444
Remediation Contractors(s):
TVffiS, Inc.
(Tuboscope Vetco International Environmental Services, Inc.)
2835 Holmes Road
P.O. Box 808 j
Houston, TX 77001
5.31
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Case Histories
Regulatory Factors
Authority
State of Alaska Department of Environmental Conservation
Requirements/Cleanup Goals
" Jl . I- , !b,' '.: i ; " , ' '
Diesel range organics <200 ppm
Results' ' _ " " V "_ VI.
Cleanup goals met volume of soil taken off-site reduced 89%.
Cleanup achieved in less than 4 months in remote location with very
difficult supply problems and unexpected contamination problems.
Operation
Type
Full-scale cleanup
Period
r " , ' . , " ' , i" , '' ;, , ' , ,i, i1 ;ll fl "
11 ',,' ' ,-", ' , ..' ., :. , , 'i.,' i,;i "*;" If "
August to November 1994
Waste Characteristics
Source""' ^ ' , , " ', ;, ' ;; '. "_
Asphalt and diesel buried at the conclusion of two airport construction
projects 1940's and 1950's.
Contaminqnt(s)
Diesel, motor oil, asphalt and asphalt hardener diesel range organics
4,000 12,000 ppm. Analysis indicated that portions of the soil contained an
80:20 mixture of diesel and asphalt.
5.32
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Chapter 5
Type of Media Treated ;
i
i
Glacial sand and till
Quantity of Media Treated
13,181 tonne (14,530 ton)
5% <200 mesh
pH approximately 8
Very abrasive mineral particles I
Primary contaminant diesel mixed with asphalt
Technology
Description
i
Screen to <1 in. to remove large tar chunks.
Soil washing using three successive stages of counter-current scouring in
augers with 13.5 aim (200 psi), 99ฐC (210T) alkaline detergent solution.
Dewatering of sand on shaker screens water cleaned by flocculation
and centrifuge water recycled processing rate 13 tonne/hr (15 ton/
hr), while using 227 L/min (60 gal/min) of water.
Significance
Cleanup of subsurface contamination that could potentially affect the
drinking water supply of a school, public buildings and residences, and re-
moval of surface tar and buried chemicals that were contaminating the resort
center supporting Alaska's Glacier Bay National Park.
Cost Data
Soil washing cost $1.4 MM, including mobilization, pilot and demobiliza-
tion total project cost $8.0 MM includes revegetation of the site as well as
excavating then shipping 20,000 drums, the buried asphalt batch plant, waste
asphalt, and contaminated fines to Washington state for land filling.
5.33
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Case Histories
': ..... "
'- !i " ' "*
Project Description
."'' ''I', '!i;;i ' "'i " :, ซ ; vn ..... nป .., i ..... ru'i'.! , :"i,|!l' j ' 4J uli'i, ป. ,' ., ''I ,ป, ',, ซ" ,M, '^ir, n i ..W
When the Gustavus, Alaska airport was built during World War II, the
drums used to ship the asphalt were buried. The airport was expanded in the
early 1950's. At that time empty and full drums of asphalt and asphalt hard-
ener, and the asphalt batch plant were buried. Apparently diesel fuel used to
clean equipment had been dumped on the sandy soil. In addition, a mixture
Of asphal aiid diesel solvent propagated mrbugh the subsurface soil from the
vicinity of the buried asphalt mixing building. A large fraction of the sub-
surface soil at the site had been contaminated by this source, that was un-
known at the time of the RI.
Equipment was mobilized by truck and barge from Houston, Texas to the
site 50 miles by sea from Juneau, Alaska piloted and production began ap-
proximately 8/i5/94. The project was completed 1 1/1/94. An on-site analytical
lab was crucial to rapid appraisal of soil washing efficiency at this isolated site.
Cose 9 Soil Washing of Drill Cuttings at
Kenai, Alaska
General Site Information
Name: Kenai Gas Field
Location: Kenai, Alaska
Owner Contact:
Brace St. Pierre
Unocal Oil and Gas
Anchorage, AK
(907)263-7615
1
Remediation Contractors(s):
TVIES.Inc.
(Tuboscope Vetco International Environmental Services, Inc.)
2835 Holmes Road
P.O. Box 808
Houston, TX 77001
. " - i \ i
5.34
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Chapters
Regulatory Factors
Authority
State of Alaska Department of Environmental Conservation
j
Requirements/Cleanup Goals
Total petroleum hydrocarbons <500 ppm, total lead <500 ppm
Results
Cleanup goals met for 95% of the soil.
Average TPH 300 ppm.
Fines were injected along with excess process water.
Operation
Type
Full-scale cleanup
Period
August to September 1993
Waste Characteristics
i
Source
Oil based emulsions used to support sand removed during drilling of oil
wells in Cook Inlet.
Contaminants) | ' '
TPH 3,000 to 20,000 ppm, 500 ppm lead
Type of Media Treated
Drill cuttings (ground sand) and glacial till
5.35
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Ill I I 11 1 1 I I I I ' i Ml i 41
Ill ' ! I ll III MIL' ,1,' " " i:. " "l'i IllllCt
Case Histories
Quantity of Media Treated
459 m3 (600 yd3)
<200 mesh ' '
Technology
Description
Soil wash with counter-current scqurijig in augers with 27 atm (400 psi),
99ฐC (210ฐF) alkaline detergent solution silt and water injected in Class n
disposal well. Production rate 9 tonne/hr (10 ton/hr) while using 98 L/min
(26 gal/min) of water.
Significance
Clean up oil well drill cuttings that had been buried for many years, and
which could have potentially threatened water supplies.
' ' >' ;; , ""; >; ; , ' '; ; "; ';'" *;."' , j ; I"," ' ' ';;; '' ' ; ,'} ';";,
Cost Data
Total project cost $31,000.
Project Description
Oil field drill cuttings are shale, sand, and broken rock flushed from a
well bore by a water in oil emulsion ("mud") as the well is drilled. They
are separated from the "mud" with shakers and cyclones, then were
commonly buried. The oil based "mud" used in the well is a mixture of
die.sel fuel, emulsiflers, dispersants, such as chrome lignosulfonate and
barium sulfate added to maintain a dense mud which can safely control
underground pressure.
' Mijn, ""'i,'1"'1,:; ;,." , ; n i ,'j.,,"iii,|ffi ,n '':,, . ' '' ,;ซ" "'' ; "' ; ' '"'i;"''; : .'" !! v '!' !r ' ' ' ', ' !; ' il:,':" i1,; ! I1'!111:!!1! i",
After a time, diesel fuel used in the emulsion carrying the cuttings from
the well can begin to leach from pit and threaten grqundwater supplies.
Thus, the old pits are gradually being cleaned up. In this full-scale test,
cuttings were cleaned from 3,000 ppm TPH to <300 ppm, while the water
and fines were injected into a Class II well. The project ended when the
packer in the injection well failed.
5.36
i
.:.',: ^t\, , i\- li1 , '
-------
Chapter 5
Cose 70 Soil Washing of NORM
Contaminated Gravel
\
General Site Information
Name: Newpark Environmental Services
Location: Port Arthur, Texas
Owner Contact:
"Pappy" Ruckstuhl
VP Operations
Newpark Environmental Services
Lafayette, LA
(318)984-4445
Remediation Contractorsฎ:
TVTESJnc.
(Tuboscope Vetco International Environmental Services, Inc.)
2835 Holmes Road
P.O. Box 808
Houston, TX 77001
Regulatory Factors
Authority
Texas Raikoad Commission Louisiana Department of Environmental
Quality
Requirements/Cleanup Goals
Radium226 <5 pCi/g
Results
85% of the soil was cleaned.
5.37
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I f
ill;;:
if;
Case Histories
!!"ii"!!;'" '"'! " '1"
ฃ."ltii:, : l! j j , tin
I- B :.r!|, , i,"!ll, , I-1" ' l
;,;';" f t : J'i,
1 li11"
Miliii : I ,
f *;!"!', ...... i, " i1 inii
'.; > .111! 1 i, ซ
i."'!
The NORM was concentrated in the -174 ft to 50 mesh fraction, which
was ground and injected into a Class n injection well.
Water and clay were also injected into a Class n injection well.
Operation " _ "
Type
Full-scale cleanup
'! :
Period
\:..::. :..;.- - , ; ;.,
February-June 1995
Waste Characteristics
Source
NORM scale cleaned from oil field pipe and vessels.
Confaminant(s)
Radium226100-700 pCi/g
Type of Media Treated
Gravel, shell, and soil
i ' i : ! , ' ' , i ' ';
' 'i, 'IN " Ii i ' ., ' , Jill
Quantity of Media Treated
2,700 drums
Technology
i
Description
Soil wash with counter-current scouring in augers with 27 atm (400 psi),
99SC (210ฐF) water, " _' ''' _""'.' '' ' _
i*'I;/
'-''.Ir I .n"'i, ' !Sl|ii.f "l, !'!,',
Illliiii. ;IIH i! : 111
5.38
-------
Production rate up to 150 bbl/day while
min) of water.
Chapter 5
using 98-151 L/min (26-40 gal/
Significance
Gravel and shell was cleaned and did not have to be injected into a Class
n injection well.
Cost Data
Total project cost $215,000.
Project Description
NORM (Naturally Occurring Radioactive Material) is radioactive carbon-
ate, silicate or sulfate scale that concentrates wherever large volumes of hot
water are processed. NORM is a common problem in oil fields where hot
subsurface carbonated brines are brought to the surface, cooled and depres-
surized. NORM then collects in vessels and pipes. Before it was common
knowledge that the scale was radioactive, the scale was cleaned from the
pipe or vessels and used as fill. Thus, significant volumes of soil have been
contaminated in pipe yards and oil fields.
Scale is a very low solubility solid, that generally occurs in a specific
particle-size range, i.e., smaller than 1/8 in., but larger than 50-150 mesh.
Thus, in clay soils with gravel or shell covers, the problem is very amenable
to inexpensive volume reduction.
Cose 11 Soil Washing of Listed Waste
Contaminated Railroad Yard Ballast
and Soil
General Site Information
Name: Union Pacific Railroad i
Location: Houston, Texas
5.39
-------
W 'I"
'(llrl
I). -i
mra i' i1 .,i
Case Histories
"!I>,J *'"" ' . I'.,:,! ' I
Owner Contact:
Paul Person
Manager Environmental Remediation
Union Pacific Railroad
Omaha, NE
(402)271-6572
Remediation Contractors^):
,;'' :,:; . , | ' TVffiS, fac. ^ \ "']' ' " _
(Tuboscope Vetco International Environmental Services, Inc.)
:.i;" '. !| i- : ;: 2835 Holmes Road '' "^ ' ' ' '"' ^'' ' | ''' ''"''"'" /""'"
'!: -f ' -:-,. i . P.O. Box 808 ' " ' ' "! '
"i:i 1 , , , ,, Houston,TX77001
,;! .', , , i* (s , , , '' .' i ,. , . >i, 1.1 . i I,, ,,i . .
".i, ":' ' "' '': , ':'. : , ;. '-'.''' I..,. |..': .. '.::": '
Regulatory Factors
Authority
Texas Natural Resources Conservation Commission
,""'!" "if. '
Requirements/Cleanup Goals
TPH <500ppm, VOC and S VOC to non-detect
: / i:" " '" ' ..', .'': ""' :: ;i ' -;".Kl .':' / ;-- ','',
Results
" ' ' ,, |, . ' : '_
95% of the soil was cleaned.
TPH was reduced 99.5% and VOC/SVOC reduced to non-detectable levels.
Operation
JYPe
Pilot
Period
January 1994
5.40
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Chapter 5
Waste Characteristics
.1 -
Source
Grease dripping from parked locomotives onto railroad ballast and spill of
D,F,K, and U wastes at railroad yard.
Contaminant(s)
TPH 25,000 to 75,000 ppm, VOC and S VOC 225 ppm
Type of Media Treated
Pea gravel, traction sand, and fine sandy loam soil
Quantity of Media Treated
i .
18 tonne (20 ton)
Technology
Description
Soil wash with counter-current scouring in augers with 27 atm (400 psi),
99ฐC (210ฐF) alkaline detergent solution;.
Water cleaned and recycled during the pilot then disposed of in the
city sewer.
Production rate up to 9 tonne/hr (10 toiulir) while using 98 L/min (26 gal/
min) of water.
Significance
Inexpensive cleanup of messy and dangerous contamination in railroad
yards.
Cost Data
No charge, estimated cleanup cost of unlisted wastes <$33/tonne ($307
ton). Cost for characteristic and listed wastes $82 to $165/tonne ($75 to
$150/ton).
5.41
-------
Case Histories
Project Description
Because a variety of materials are transported on railroads, the soil near
the tracks and in railroad yards can become highly contaminated with almost
any material. The least obnoxious of these is grease dripping from locomo-
tives when they are parked. This material is classified as commercial non-
hazardous wastes, but must be regularly cleaned as a house keeping measure.
Another waste is diesel spills in fueling area. A final type of wastes are
spills of chemicals and listed wastes during transport to disposal sites.
TVEES processed over 18 tonne (20 ton) of greasy ballast and yard soil
contaminated with listed wastes. TPH was reduced from 25,000 and 75,000
ppm to less than 500 ppm, and both VOC's and S VOC's were reduced below
detectable levels with a few minutes of scouring with chemical solutions in
its auger washing equipment.
Case 1 2 Soil Decontamination
Treatgbility Studies at the Warm Waste
l*ond, Idaho A/ctfMerr J^
Laboratory, Idaho Falls, Idaho
General Site Information
Name: Warm Waste Pond, Idaho National Engineering Laboratory
Location: Idaho Falls, Idaho
i
Owner: U.S. Department of Energy
Owner Contact:
Lisa Green
U.S . Department of Energy
........ ! " Idaho Falls, ID ............................. ........ " ..... ..... " ..... ................
I
I "IT "i"1
5.42
liil'1 II.i , . J ,<: 'i"',|. '.. , ft ,Jn, i
-------
Chapter 5
Regulator/ Factors
Authority
CERCLA:
ROD Date 12/5/91; and
DOE Lead Agency and PRP.
Requirements/Cleanup Goals
12/5/91 ROD requiring 60% soil recovery by sieving, 90% removal of
total contamination, and residual cesium contamination level <690 pCi/g in
soil returned to excavation.
Results
Cleanup goals for cesium decontamination could not be met using any
treatment tested. Even low surface area +8 mesh fraction partitioned by wet
sieving did not pass cleanup criteria. Cesium decontamination of up to 90%
could be achieved with hot acid, but almost one third of the soil mass was
dissolved, generating unacceptable secondary waste volumes. Sequential
extraction indicated little preferential distribution of cesium in any chemical
phase, with most of the cesium residual bound in or on the mineral lattice.
Operation
Type
Treatability study
Period
1991-1993
5.43
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Case Histories
Waste Characteristics
Source
Cooling tower and low level radioactive wasie discharge to evapora-
tion pond.
It , ' ' i , i| I:1 -t fir , i1',,.- ,' . : ", ,",",,; ,. -: "; ' . i..' '"' ' . it'i'T.'a
J', \' "Jtlf ' J Contaminant",, , '". '_ " ."","|'.. ' .' 'V."'.
Cesium: -137 Ave 11,500 pCi/g,-8 mesh 22,000 pCi/g;
Cobalt: -60 Ave 4,620 pCi/g, -8 mesh 6,200 pCi/g; and
Chromium: 338 mg/kg.
Type of Media Treated
Coarse gravel/sand/silt mixture
Quantity of Media Treated
" 14,159 m3 (500,000 ft3)
Coarse gravel/sand/silt mixture, >70% +8 mesh
pH approximately 8
Technology
Description
i-1 . ... ': ,, " Chemical: [
ambient and hot mineral acid extraction;
* selective sequential extraction; and
ion exchange with salt brines.
^:,"".' s|. I'.! i''*i i .' ' i " - ''..''.' ป . "" . " . (i '" ' i iii.11 ~ > .;i ' "f i
Physical:
wet sieving.
-------
Chapter 5
Significance j
Extensive treatability study efforts were completed using a wide variety
of chemical decontamination techniques which showed that cesium appears
to be irreversibly bound in the silicate mineral matrix, and unavailable to
recovery without substantial dissolution of the matrix. Preliminary scoping
studies were not adequate to characterize potential for cleanup prior to ROD.
Cost Data
Estimated cleanup cost for acid extraction, including secondary waste
treatment, but not disposal, was $l,414/tonme ($l,287/ton) for the simplest
conceptual flowsheet using neutralization and precipitation of sludges. Total
cost for this option was estimated to be almost $57,000,000.
Project Description
The Warm Waste Pond is located in the southwestern portion of the Idaho
National Engineering Laboratory, an 890 mi2 reservation 32 miles west of
Idaho Falls, in southwestern Idaho. The Idaho National Engineering Labora-
tory is under the purview of the DOE, and operated to do nuclear reactor
research and fuel storage and processing. The pond consists of three cells,
excavated in 1952, 1957, and 1964 covering a total of approximately 4 acres.
Normal annual precipitation is about 9 in., and the underlying strata are
made up of interbedded basalt flows and mixed gravel, sand, and silt.
Over 40 years of operation, the pond is estimated to have received over
18.9 billion L (5 billion gal) of reactor cooling water, radioactive wastewa-
ters, and regeneration solutions from ion exchange columns. Though
samples have been characterized to ten feet below the surface in efforts ex-
tending from 1983-1990, contaminants were found chiefly only in the top 2
ft. The most prevalent contaminant found is chromium. Introduced to the
pond as a hexavalent corrosion inhibitor until 1972, the chromium has been
reduced over time to the less toxic trivalent form.
The ROD required treatment of the top 2 ft of sediment, or about 14,159
m3 (500,000 ft3) of material. Initial scoping studies indicated that about 60%
(by weight) of the matrix could be separated by sieving at 8 mesh, and the
relatively low surface-area material could be water washed and returned to
the excavation. The finer material could be extracted with hot mineral acids
to achieve the required overall decontamination, with about 8% (by weight)
5.45
-------
I /.I ..... lit'1 I
: < > iiiPii ...... B!"i' BI ....... infill! ..... tmm>. ...... in ..... ill * ....... "i: ';
, !!ซ';' .' '' " I',,' '- i '"<:, .n#l
1"*';
V1 -i. ' J'i'iii'11
'?,' ' ;|I;,:I!I!"IS' Illl'lli:1'1;:"'','If IIP1';111;liป'! '"I III"'! ! Kt'II' ..Ill: .'.:i If '"""lira! 11.1 ill"! !'"*"II
, ,T,L ;:';- ',,,;;1 i-f (.[ i, s .ป. ; 'i;;,: ,, >; , i Li;:1 i.i";.:?(
. ./ ih ; :>,
Case Histories
i 'fun, Ilii ,
I!'/
I
lost to dissolution. Follow-on studies to support the cleanup indicated that
s'i' "' i'",, " ' ' ""'hi. '" ' '/i' ' n j' i",'.HI',i!ii '""i'"1" :;!' ^..ii" ปlii,iby i' ," .,, I <ซh,i<,,ii II T,v "& ::: " : J ". '"ฎj ii j |
the large material separated by screening did not meet the required residual
cesium limits, and far greater extraction efficiency would be required with
the finer material to meet the overall goals stated in the ROD. Up to 90%
decontamination was achievable with near boiling 3M nitric acid, but about
1/3 of the soil matrix was dissolved in the process^ Parallel studies were
performed with sequential extraction to determine now the cesium was
bound in an effort to develop a more selective extractant to remove the ce-
sium without gross dissolution of the matrix. The soil was first treated with
a potassium brine to remove exchangeable cesium. Then the carbonate,
hydrated metal oxide, and organic phases were removed as selectively as
practical. Over 20% (by weight) of the soil was dissolved by the time the
underlying mineral matrix was stripped and yet only about 18% of the ce-
sium was removed. The cesium was apparently irreversibly fixed in or on
the silicate matrix, unavailable to chemical decontamination without strong
etching of the mineral surface.
, .'.'': i,, ai ; ' ":!!ป"I;1" !', I I I I l| I I III Hill
Estimated costs, secondary chemical wastes, and the risks of processing
with near boiling, strong nitric acid made the proposed cleanup unaccept-
able, and the lower risk, lower cost interim action chosen was capping. The
difficulties shown for chemical extraction of cesium at this site are mirrorecf
by data from many other locations including Oak Ridge, Tennessee and
Hanford, Washington.
T'lllllli'1' .Jlhllll
III. t
Cose 73 Son Washing Pilot Study at the
300-FF-1 QperabJe Unit, The Hanford Site,
Kichland, Washington
General Site Information
Name: 300-FF-l Operable Unit, North Process Pond, The Hanford Site
Location: Richland, Washington
5.46
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Chapter 5
Owner:
U.S. Department of Energy
P.O. Box 550
Richland,WA 99352
Owner Contact:
i
Ronald D. Belden
CH2M HILL Hanford, Inc.
450 Hills Street, Door 5
P.O. Box 1510
Richland, WA 99352
(509) 372-9601
Remediation Contractors):
Alternative Remedial Tecnologies, Inc.
14497 North Dale Mabry Highway, Suite 240
Tampa, FL 33618
(813)264-3506
Regulatory Factors
Authority
CERCLA:
On May 15,1989 (amended May 1991 and January 1994), the
DOE, the Washington State Department of Ecology, and the US
EPA signed an agreement (Tri-Party Agreement) that contains a
plan for cleanup; and
DOE lead agency.
i
Requirement/Cleanup Goals
Cleanup Goals are shown in Table 5.13.1, the criteria for the clean frac-
tion of soil was greater than 90% by weight. The criteria for the contami-
nated soil fraction resulting from the process was 10% or less of the total
soil processed on a weight basis.
5.47
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Ill'
'ill.!1;'1;:,
nil .LI. in.'mi
.
[!"'!'! i>;
II!'' J'"' " ''"
ll'iihl'lli,:!' ,,i : ',1,1 ,"'
'!ป i' "',,
if, ;,:j,, i
LI :;/
it'1" i
i :
,,'"'
i
"' ' '"'i-B!1.'" -i """ ., ': ': '.' . ". 'i " '.'.," , n ' , , j,,,::
i ii ' i I, ii' ii ': i'i niii: "ii
! "! "i !' i! '" ' ' ' "!" "1 "'" - . '. ' '" . '. :'!li|1' " ' "
Case Histories
MP" '' II,, llll "" ,'!' ! ! , ป , ' ,' " ' !l ' ,!|' 'li 1 |l
fli
"Si
3,1
"'nil
n 'i ,! ifl;! ' , '1 ,'"' , , ' ,i,| ' , "" i!,
Ili'i ,: '' 'll M. '"i ' ' ' "' ! M ' ,, 'i, i
; :;- ':. ' .. ' ;,:-, ". , " Table 5.13.1
!,'" "i!:!" '' ,,,: ;,;.' ';". ' ' ; , ' ": ;; cledriup Goals
i" :',:,!, i " , v;/' " "" "" ,; -i , ,'"ป , j 'iiiiiiSL,, I*!, iii1 ;i; r; j.'.| !v:ni:.,! jf;.,1
In iil.,i'ii , !" ,, ป ' '* ' , , ' , ,! ii""111 J'STI! ',,!'" .ii!1',11!!:,,!':1.!,,!!, : ' . ',ป 1 ,
, ' ' ' '", _ :," ':' r1 L '
i1 '' ,, , "''' i i
1 , , , , i
,' ,
'';,,; ,' i" . ;, ;;i 'i ;'''i , ' " , , ;,' ,, | -l nr nf!
Constituent Soil Cleanup Levels
"I'l'ii ..i'"1'"' - ; ':J" : '- : ' : ' '* :~^J ~ '~~~ ' ~
;, ....... E'
l;'il "M
Copper (ppm)
U-238(pCi/g)
U-235 (pCi/g)
Cs-137 (pCi/g)
Co-60 (pCi/g)
H.840
15
3.0
Results
The soils met the principal objective of the study which was to determine
if the physical separation approach would be effective in attaining a 90%
volume reduction while meeting the defined test performance criteria. Vol-
ume reductions of 93.8% and 91.4% by weight were attained for the two soil
types processed. Cleanup standards attained are shown in Table 5.13.2.
III!!! i
Table 5.13.2
Cleanup Standards Attained
1, ' ll II
Contaminant
Cu (ppm)
U-238 (pCi/g)
U-235 (pCi/g)
Cs-137 (pCi/g)
Co-60 (pCi/g)
Process Oversize
199
5.5
03
0.05
<0.04
Concentration
(Clean) Sand (Clean)
' s'' 1.180 '
28J
1.4
03
<0.06
Test Performance Standard
11,840
50
15
3.0
1.0
5.48
"i
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Chapter 5
Operation
Type
I
Pilot study
Period
March 1994-June 1994
Waste Characteristics
Source
Soils underlying process ponds and trenches that held wastewaters from
nuclear fuel fabrication operations.
I
Contaminant(s)
See Table 5.13.3
Table 5.13,3
Feed Concentration of Contaminants
Contaminant
Copper
U-238
U-235
Cs-137
Co-60
Feed Concentration
2,800 ppm
132 pCi/g
4.5 pCi/g
0.13 pCi/g
0.08 pCi/g
5.49
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I!11/1!1!!!1!1!1!..; ,?r "WJii'ilii.' milt I"'"IISIR:' I "fli"1,;!1!! ''-Mill ,' . i!!'"iil,'l 1
Case Histories
ill!! iilPh i,,!
:;;,:! ;!: J'i*
III!!1! iyirii'::"1:1'1! I 'Pi'
I! "Sill I . , . I i.T f
I" T 'I ", ,!'
IE III , ('I1 it .:
Type of Media Treated
Coarse granitic sands and gravels. Two soil types were treated during the
testing: a natural soil contaminated with low levels of uranium, cesium,
cobalt, and heavy metals, and a natural soil contaminated with a uranium-
copper carbonate material that was visually recognizable by the presence of
a green sludge material in the soil matrix. The "green" material contained
significantly higher levels of the same contaminants.
Quantity of Media Treated
315.9 tonne (348.2 ton) total
Technology
Description
Soil washing/physical separation, physical separation is one member of a
broad group of technologies referred to as soil washing. The 9-14 tonne/hr
(10-15 ton/hr) physical separation plant consisted" of the following units:
50 mm vibrating screen;
feed hopper;
>2mm.double-decked vibrating wet screen;
hydrocyclone separation system;
I
sludge settling tank;
attritioning unit;
process water tank;
sludge holding tank;
: , . ;' , i ' ,, ' - "lit1:1 mii"i i| -,. " i" !'!: ,j si',;,: i
dewatering unit; and
n i|
sludge dewatering unit.
Significance
This was the first soil washing pilot study performed at the Hanford Site.
The study demonstrated that soil washing could effectively meet the princi-
pal objective of the study which was to determine if a physical separation
5.50
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Chapter 5
approach could be effective in attaining a 90% volume reduction while meet-
ing the defined test performance criteria. Also of significance was the de-
contamination and removal of the plant from the site.
Cost Data
Value of contract was $1.1 million.
i
Project Description
ART was contracted to the Westinghouse-Hanford Company for all
phases of the pilot study which included:
mobilization and set-up of the pilot plant;
plant shakedown;
preparation of site manuals including:
site operations manual;
quality assurance project plan;
test procedures;
performance of all phases of the soil washing pilot test;
plant decommissioning and decontamination; and
project technical report.
The test was conducted on soils contaminated with low-level uranium,
metals and organics. Contamination originated from nuclear materials pro-
duction operations at the site from World War H until 1975. Soils from two
areas within the OU were processed (1) 272 tonne (300 ton) of soil contain-
ing metals, organic materials and low-level uranium and, (2) 73 tonne (80
ton)(excavated) of soil containing elevated concentrations of copper and
uranium.
The tests for the 272 tonne (300 ton) of soil were conducted in three seg-
ments: (1) the pre-test run, (2) the verification run, and (3) the replication
run, as follows:
(1) The pre-test run provided for startup of the equipment and initial
processing of soil. Adjustments and fine-tuning to the plant were
made, based on the results of the pre-test run. During this run, 45
tonne (50 ton) of soil were processed.
5.51
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Casฉ Histories
(2) The goal of the verification run was to demonstrate that the
equipment and process could[achieve the specified 90% reduc-
tion by weight of contaminated.'material, and to meet the treat-
ment standards. During this run 113 tonne (125 ton) of soil were
" -:;, ' ., - -;,;,; ;,v ; ;,. processed.
(3) Theigoal of the replication 'run was to confirm that the results
achieved in the verification run could fee replicated. During mis
ran, an additional 113 tonne (125 ton) of soil were processed.
ART also performed a test on 73 tonne (80 ton)(excavated) of soil con-
taining significantly higher levels of uranium due to the presence of a ura-
nium-copper carbonate precipitate. Attrition scrubbing added to the process
units to achieve improved treatment performance.
The pilot plant utilized at this site had a throughput capacity of 9-14
tonne/hr (10-15 ton/hr) in a mobile, easily erectable configuration. The plant
consisted of a feed hopper, a double-decked wet screen, hydrocyclones,
attrition scrubber, sand dewatering screen, sludge thickening and dewatering
units, and the required supporting peripheral equipment. The pilot study was
success.ful in meeting the goal of >90% reduction by weight and was also
successful in achieving the specified test performance standards.
Upon completion of the tests, ART submitted a written report to
Westinghouse-Hanford Company for incorporation into a Feasibility Study.
i! i i ' ' *?":' :"",: . ;" i' - " ". " , ' "' r , , i ,
111 ' " " ""*' "i ;' :" Reference
1. Westinghouse Hanford Company. 1994. 300-FF-l Operable
Unit Physical Separation of Soil Pilot Plant Sti^. iV$^$D:
EN-TI-277, Rev. 0, Prepared for the DOE Office of Environmen-
tal Restoration and Waste Management.
5.52
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Chapter 5
Cose 74 Full-Scale Soil Washing at the
King of Prussia Superfund Site, Winslow
Township, New Jersey
General Site Information !
Name: King of Prussia Superfund Site
Location: Winslow Township, New Jersey
Owner: Winslow Township, New Jersey
Owner Contact:
Frank J. Opet, PRP Committee Chairman
Johnson Matthey
2001 Nolte Drive
West Deptford, NJ 08066
(609) 384-7000
Remediation Contractors):
Alternative Remedial Technologies, Inc.
14497 North Dale Mabry Highway, Suite 240
Tampa, FL 33618
(813)264-3506
Regulatory Factors
Authority
CERCLA:
ROD Date 9/28/90;
Unilateral Administrative Order April 1991 issued to Potentially
Responsible Party Committee; and
US EPA lead agency and PRP.
5.53
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Case Histories
Requirements/Cleanup Goals
9/28/90 ROD defined five components of remedial activities pertain-
ing to contaminated media, including the area relevant to this case his-
;i ' ' - . :'-' i". ;"ป=ป ' tory (Component 1):
Component 1 The metals-contaminated soils adjacent to the
lagoons, the sludge in the lagoons, and the sediment in the swale
(Operable Unit 1);
Component 2 The buried drums and soils contaminated with
volatile organic compounds located in the northwest section of
the site (Operable Unit 2);
Component'sTwoi tankers and their contents located near the
southeast sections of the site;
Component 4 The groundwater at the site contaminated with
organics and metals (Operable Unit 3); and
!;; . i ''''.'':j ''j''- .'.'.'.'! ComponentsThe surface waters, sediments and biota of the
, ,;,.;,,. , ,.-, ,r, , ..,,'. Great Egg Harbor River.
the;1990 ROD identified cleanup> goals for i I metals in the soil in the
area adjacent to the lagoons, sediments in the swale, and sludges in the la-
goons. These goals are presented in Table 5.14.1.
vE' '":':::: .' . :., T :: """ , ReSUltS ' ' ' ,', . ' ' , ^ ' , ..".' . " [[
' "' ;"l!"'!":' "''' ' -'"' ' ' ' ; ! ';ii ...The'remedial activities for Component''! were led by "the fRPs with US'
iW".; f',1' i"'if- :i- * t1 , i .. yB;.'. '.ป!(.
EPA oversight. Cleanup goals were met forall eleven metals. Cleanup
goals were achieved in less than four months. Cleanup standards attained
for the primary contaminants are presented in Table 5.14.2.
"Operation ' '"
Type ^ .......... ................... ....... ^
Full-scale '
Period
June 18, 1993-October 10, 1993
" ' "" i 'ii IT' ' ' I1"'1'!;. ." ': i"'1 i 'i. ' j i,
, - ... ' : -. ' ' ' ', i;';" '">" ...... .-h'.
...... 5,,54 ........ .......
i /'iiir ' '> .''
I;!.,;,! , ;: j,|,"',,!
-------
Chapter 5
Table 5.14.1
Cleanup Goals
Constituent
Arsenic
Beryllium
Cadmium
Chromium (total)
Copper
Lead
Mercury
Nkkel
Selenium
Silver
Zinc
Soil Cleanup Levels (rag/kg)
190
I 485
107
483
3,571
500
1
1,935
4
5
3,800
Primary contaminants of concern were nickel, chromium and copper.
Table 5.14.2
Cleanup Standards Attained
Contaminant
Nickel
Chromium
Copper
Clean Product
(avg. cone, mg/kg)
25
73
110
Waste Characteristics
Source
Six lagoons used to process liquid industrial waste.
5.55
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I'i 'III!:,!1!11' ''V: ' I: ;i If" '! ir:11''!!,,, i'i1",
IM:!,
J' tin :,;:j!iS
1 iiin ,ii mil1; .;IH
', ,1" , I ' Pllli'" "
Case Histories
| , , , ,
Contaminant(s)
: Metals "
beryllium, chromium, copper, nickel, zinc, lead, mercury;
highest metals concentrations in sediments chromium (8,100
mg/kg), copper (9,070 mg/kg), mercury (100 mg/kg); and
highest metals concentration in sludge chromium (11,300
mg/kg), copper (16,300 mg/kg), lead (389 mg/kg), nickel
/. ;,,,;:; (11,100 mg/kg). ^ i ^ " n ^
Type of Media Treated
Soil and sludge
Quantity of Media Treated
17,418 tonne (19,200 ton)
Moisture content of approximately 15%
pH of approximately 6.5%
Technology
Description
Soil washing
Materials handling:
selective excavation of metals-contaminated soil using visual
inspection, confirmed using on-site x-ray fluorescence.
Soil washing system:
four components screening, separation, froth flotation, sludge
management; rated feed capacity of 23 tonne/hr (25 ton/hr);
screening multiple screens; coarse screen (>8 in.) and process
oversize (>2 in.); wet screening of <2 in. materials;
separation hydrocyclones separate coarse- and fine-grained
materials;
. , , ' " ' ' , 'i ' -;i f ' "" ''I'1 ' ' 'I'M!.1 Hi'1 !" ' ,iii!',i"l il I,', j, M , . . ' ' , '"' >,li, , ' ,' nil!1 l!|! ,' 'ซ 1 1 .""I
froth flotation air flotation treatment units; and
5.56
i
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Chapter 5
sludge management overflow from hydrocyclones sent
through clarifier, sludge thickener, filter press; filter cake dis-
posed off-site; water reused for wet screening.
Significance
US EPA's first full-scale application of soil washing to remediate a
Superfund site. Innovative on-site monitoring technique; selective excava-
tion techniques, including use of x-ray fluorescence, to screen soil for
cleanup. Data from demonstration run expedited the design schedule of the
full-scale unit by more than a year.
Cost Data
The total cost for this application was $7,700,000, including off-site dis-
posal costs for the sludge cake. Selective excavation, confirmed using on-
site x-ray fluorescence, reduced the overall costs for the application by re-
ducing the amount of soil requiring treatment by a factor of two.
. ' i
i
Project Description
Background
The King of Prussia Technical Corporation Site is located in Winslow
Township, New Jersey, about 30 miles southeast of Philadelphia. The site is
situated on approximately ten acres within the; Pinelands National Reserve,
and adjacent to the State of New Jersey's Winslow Wildlife Refuge. The
KOP Technical Corporation purchased the site in 1970 to operate an indus-
trial waste recycling center. The operation wais not successful, and in 1985
the site was placed on the National Priorities List. In 1990 a Record of De-
cision (ROD) was issued for the site, and soil washing was specified as the
cleanup technology to be used for remediating the soils. A group of Poten-
tially Responsible Parties was issued a Unilateral Administrative Order to
implement the requirements of the ROD.
i ;
i '
Preliminary Activities .
Two major preparatory steps were taken priior to beginning full-scale soil
washing activities:
5.57
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Case Histories
IV III'1,.!:"
Siliiii'1' '
"} 'if:
!: ฃ
(l) A Treatability Study to Determine the Applicability of Soil Wash-
ing to the Site. During the Treatability Study, site soils were
separated into particle-size fractions and particle-size distribution
curves were constructed. Each resulting fraction was analyzed
for the target contaminants, and bench-scale studies were con-
ducted to determine the treatment unit operations to be imple-
mented in the full-scale operation.
(2) A "Demonstration Run" of 'Actual"Site Soils Prior to Final De-
sign of the Soil Washing Plant. Because this was a new technol-
ogy to the US EPA, some questions were left from the treatability
and bench-scale studies. Therefore, to fully confirm the effec-
tiveness of the technology on KOP soils, a "demonstration run"
was planned and implemented for actual KOP site materials at
Heidemij's full-scale fixed facility in Moerdijk, The Netherlands.
With US EPA and VROM (the equivalent Dutch agency) ap-
proval, 150 tonne (165 ton) of KOP site soils were shipped to
Moerdijk. A one-day treatment operation was performed with
the equipment configured as recommended in the preliminary
design for the KOP soil washing plant. The operation was suc-
cessful in demonstrating the effectiveness of soil washing in
treating the site soils. Soils were remediated to levels well below
the ROD-specified standards.
Preparation for Full-Scale Operations
Following the demonstration run, the firm of SALA International was
contracted by ART to manufacture a 23 tonne/hr '(25 ton/fir) soil washing
plant, and the plant was delivered to the site in May i9'9"3i After erection of
the plant on-site, a pilot run was conducted on 907 tonne (1,000 ton) of con-
taminated soils excavated from the site^ The pilot run was successful, again
with cleanup levels well below the ROD-specified standards. As a result, US
EPA granted prompt approval to proceed with full-scale remediation.
Full-Scale Operations
Full-scale operations at the KOP site began on June 28,1993. The project
was,performed with full US EPA oversight and in accordance with the ap-
proved Site Operations Plan. The process and products were controlled by
5.58
;,l
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Chapter 5
on-site x-ray fluorescence using previously prepared site matrix-matched
standards and confirmed by off-site CLP analysis. Correlation between the
approaches was excellent. The soil washing operation was completed on
October 10,1993, and the facility was disassembled and removed from the
site. The project treated 17,418 tonne (19,200 ton) of soil with a volume
reduction of greater than 90% on a dry solids basis.
Reference
1. US EPA 1995. Remediation Case Studies: Thermal Desorption,
Soil Washing, and In Situ Vitrification. EPA-542-R-95-005. Of-
fice of Solid Waste and Emergency Response. Washington, DC.
March.
Case 75 Soil Washing at the Monsanto
Site, Everett, Massachusetts
i
General Site Information I
i
Name: The Monsanto Site j
Location: Everett, Massachusetts !
Owner: The Monsanto Company
Owner Contact:
Bruce Yare j
Monsanto Company
800 North Lindberg Boulevard
St. Louis, MO 63167
(314)694-6370
Remediation Contractors): ;
Alternative Remedial Technologies, Inc.
14497 North Dale Mabry Highway, Suite 240
Tampa, FL 33618
(813) 264-3506
5.59
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' I
-*ii'.i'; ซ i Hi '
Case Histories
Regulatory Factors
Authority
Massachusetts Contingency Plan, Phase III Remedial Action Plan
Requirements/Cleanup Goals
I
See lfcble 5.15.1
t '
1: t'l
Table .5.15.1
Cleanup Goals
Cleanup
Contaminant
Requirements (m'g/kg)
Goals (nig/kg)
BBHP
Naphthalene
Phthalic Acid
< 10,000
< 10,000
< 1,000
3,000
3,000
300
Operation
Type
Full-scale
Period
May-November 1996
Waste Characteristics
Source
Chemical plant
5.60
J 'i
"la, ',- t"
I "i "'"ill'1; JTI1
> " ..... !*,,'
'. ,,iiซif,; iilliliiil ' ...... ii.'sh .i-;,:,1: :,iiir-"i!,;' -t ......
*!'* :' ' '',''''' ! " '' ' I1 i ' ' " ''" , '"'' I
..j,;!1,.,;'! - f fin, v ;,,!ป!;:- '.:.'J?'i
-------
Chapter 5
Contaminants)
bis (2-ethlhexyl) phthalate (BEHP);
phthalic anhydride process residues (PAPR) containing Naph-
thalene; and
phthalic acid.
Type of Media Treated
Soil
Quantity of Media Treated
8,709 tonne (9,600 ton)
Technology
l
Description j
Soil washing and bioremediation feed preparation
Plant units:
-
trommel;
feed hopper;
wet screen;
hydrocyclones;
attritioner;
sand dewatering screen;
sludge settling tank; and
plate and frame filter press.
i
Significance
In addition to the fine fraction containing PAPR the oversize fraction,
typically unimpacted, also contained PAPR. An innovative treatment train
was designed for treatment of this fraction. The soil washing technology
effected considerable cost savings over baseline technology.
5.61
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Case Histories
Cost Data
Total cost was $900,000 for soil washing and bioremediation feed
preparation.
Project Description
The Monsanto Company operated a chemical plant at this 84 acre
brownfields site from the mid-1800s to 1992. Manufacturing activities re-
sulted in soil impacted with naphthalene, BEHP, arsenic, lead and zinc.
Since operations ceased, the plant facilities nave been dismantled or demol-
ished, and the site was being remediated for construction of a 60,408.9 m2
(650,000 ft2) shopping mall. Monsanto performed the cleanup at this site
under the Massachusetts Contingency Plan. Brownfields are potentially
contaminated industrial or commercial urban properties that have been aban-
doned or underutilized, but are suitable for redevelopment to help restore
economic vitality to a community.
ART began preparations for soil treatment operations in May 1996 with a
treatability study to determine the particle-size contamination and to provide
data for design of the plant. The study showed that the fines fraction (<2
mm) contained BEHP, and the oversize fraction (>2 mm) contained PAPR.
The process-flow diagram design included a trommel, feed hopper, wet
screen, hydrocyclones, attritioning, secondary hydrocycloning, sand dewa-
tering, fines thickening and consolidation, and sludge dewatering. Treatment
of fines was achieved by bioremediation performed by another contractor.
ART mobilized its 13.6 tonne/hr (15 ton/hr) soil washing plant to the site
and configured it in accordance with the optimized process-flow diagram.
Soils consisting primarily of oversize and coarse material, with less than
20% silt and clay, including construction debris, demolition rubble and other
fill, were excavated from several areas around the site and delivered to the
plant for processing. The soil was field-screened to remove gross oversize
material, producing a plant feed <2 in. The <2 in. material was fed into the
plant and through the wet screening unit, producing a process oversize >2
mm, and a wet slurry <2 mm. The process oversize, containing PAPR, was
staged outside the plant for further treatment, the wet slurry was fed to the
hydrocyclone separation unit, producing a coarse sand fraction and a fines
fraction. The coarse sand fraction was directed to a dewatering screen and,
''!! II' : ,., i ' 'in
5.62
{ft-
Aiif ,1 111!,"1
i'i ..
-------
Chapter 5
after testing, was returned to the site as clean backfill. The fines fraction was
degraded in a bioslurry system operated by another contractor. The oversize
material >2 in. contaminated with naphthalene concentrations higher than
treatment targets was further treated by attritioning. Overall, a volume re-
duction of 93% was achieved for the project.
Cose 16 Soil Washing Pilot Study at the
RMI Titanium Company Extrusion Plant Site
General Site Information
Name: RMI Titanium Company Extrusion Plant Site
Location: Ashtabula, Ohio
Owner:
RMI Titanium Company, Inc.
1000 Warren Avenue
Niles, OH 44446
Owner Contact:
James W. Henderson
RMI Environmental Services
P.O. Box 579
Ashtabula, OH 44005-0579
Remediation Contractor(s):
Alternative Remedial Technologies, Inc.
14497 North Dale Mabry Highway, Suite 240
Tampa, FL 33618
(813)264-3506
Authority
RMI Decommissioning Project (RMIDP) sponsored by the DOE Office
of Environmental Restoration (EM-40)
5.63
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Case Histories
Requirement/Cleanup Goals
'.- .: :'', :; -,: '-; ',;. ". :.*,> ;,'"? .\ty.i' ' ;: i .. . , . ~. \ .-..
To determine the feasibility of using a physical separation/carbonate ex-
traction process in a full-scale application at Ashtabula through conduct of a
pilot study. The operational and performance criteria used to assess this
pilot study included the following:
the removal efficiency of the process as measured by the uranium
activities in the feed soil versus the uranium concentrations in the
treated soil,
the ability to treat RMI soil to meet the 30pCi/g free release
standard,
the ability to achieve a significant volume reduction in the
amount of soil requiring off-site disposal, and
the ability to demonstrate a mass balance for uranium.
": . ' ] '', . ": ' LI ":~1
Results _ . i ' _, ip |( |_" ^' ~M' ,' .IP "^'
the performance of the pilot testing validated earlier bench-scale find-
ings, particularly with respect to the removal efficiencies and the perfor-
mance of selected system components. Removal efficiencies of 84% to 90%
were achieved, and the clean soil met the treatment standard of 30 pCi/g
uranium. Table 5.16.1 demonstrates some of the results achieved.
Operation
Type
Pilot study
Period
January 7,1997 to February 14,1997
5.64
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Chapter 5
Table 5.16.1
Cleanup Results
Pile Area
2 Run 1
AreaD
3 Run 2
AreaD
4 Run!
AreaC
S Run 2
Uranium Activity of
Feed by Alpha Spec
(pCtfg)
129
90
133
145
Leaching
Time
(hr)
1
2
1
1
Waste Characteristics
Treated Soil
Alpha
XRF Spec
(pCi/g) (pCi/g)
8 12
11 12
10 13
17 14
Average
Removal Efficiency
Alpha
XRF Spec
94 91
88 87
92 90
88 90
90 89
Source
The primary management practice that contributed to contamination at
the RMI site was the uranium manufacturing process. Particulate uranium
was generated in the extrusion building during operation of uranium extrud-
ing and machining equipment. Hoods and fans were used to exhaust the fine
uranium dusts and fumes outside the building. Particulate deposition from
the exhaust system contaminated the surrounding soils with uranium.
Contaminants(s)
Uranium
Type of Media Treated
The contaminated media at this site are clay soils with a small sand frac-
tion or non-native gravel that was used for plant service roads. The uranium
at the RMI site is generally stratified within shallow topsoils with highest
activities found in the top 6 in. of soil.
5.65
-------
ป: i' it
i; fit)
Case Histories
i;,!",: ,
I' , "ill
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ill" VI! i]|| ; . ] 11
:
>ซ. III- ' !,>
Ui ';.ji|
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fill:
-------
Chapter 5
Reference
1. U.S. Nuclear Regulatory Commission. 1981. Disposal or On-
site Storage of Thorium or Uranium Wastes from Past Opera-
tions. Branch Technical Position. 46FR52601. October 23.
2. Soil Washing Treatability Study Report of the RMI Extrusion
Plant Site. November 4,1996.
3. Soil Washing Pilot Project Report for the RMI Titanium Company
Extrusion Plant Site. 1997. Volumes I and II. Ashtabula, OH.
April 22.
-------
"ill
-------
SOIL FLUSHING
-------
If!',;, ; Si ' "i I
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iJl" : II iulll ,,!
,11,'1 11
,ป[ -I
-------
Chapter 6
APPLICATION CONCEPTS
In situ soil flushing is a process used to accelerate the movement of con-
taminants through unsaturated or saturated materials by solubilizing, emulsi-
fying, or chemically modifying the contaminants. A treatment solution
made up of water, enhanced water, or gaseous mixtures is applied to the soil
and allowed to percolate downward and interact with contaminating chemi-
cals (US EPA 1993). Contaminants are mobilized by the treatment solution
and transported down to a saturated zone, or within the saturated zone,
where they are captured in drains or wells and pumped to the surface for
recovery, treatment, or disposal (Magee et al. 1991).
6.1 Soil Flushing Development
Virtually all in situ soil flushing relies on various applications of pump-
and-treat technology. Pump-and-treat groundwater cleanup methods use
natural groundwater flow through the aquifer to flush out the contaminants
and capture them using one or more pumping wells. The contaminated
groundwater is treated to destroy the contaminants or render them harmless.
The treated water is then released to the environment or recirculated. In a
recent American Chemical Society study, Shiau et al. (1995) suggest that
"remediation of dense nonaqueous-phase liquid (DNAPLs) residual satura-
tion (the residual saturation is defined as the degree of saturation of a
soil sample at high capillary pressure) can require hundreds to thousands
of pore volumes to achieve drinking-water-standards cleanup levels us-
ing conventional pump-and-treat methods." (A pore volume is the
amount of mobile fluid that can be contained in the pores of the soil
being flushed.) See Section 7.4 for details. j
Technically, in situ processes are not limited to pump-and-treat technol-
ogy. For example, the petroleum industry has devoted much effort to
-------
"!ii till ( I
ifjl" ijljll1" |
.1 "iil!'.'
'it' ,1,11'" ; i II, ซ
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!, M
develop methods that enhance oil recovery from petroleum reservoirs con-
taining a mixture of hydrocarbons and water. Oil in a petroleum reservoir is
usually found floating on a water table at great depths. In the oil industry, an
effort is made to pump above the oil-water contact line to prolong crude oil
recovery and minimize dilution with water. The waste industry uses skim-
mer pumps to accomplish the same objective. After some time, pumping
causes oil levels to drop in an oil reservoir and secondary recovery com-
mences with water flooding. Water is separated from the oil-water mixture
and the separated water is supplemented ami, if necessary, reinjected. Ad-
vanced wellfield patterns are applied to drive the oil to collection. The rein-
jected water increases the pressure in the reservoir to renew the flow of wa-
ter and oil to the collector wells. Surfactants, polymers, and chemical agents
may be added to further enhance oil recovery.
Many waste sites are similar to petroleum reservoirs except for their
depth. Virtually all waste sites have contaminants at Sepths less than
100 m (330 ft), while petroleum reservoirs are typically 1 km (3,300 ft)
deep, or more. The petroleum remedial processes that are potentially
applicable include:
the injection ofsurfactants and/or thermal energy to efficiently
mobilize contaminants from thesoil pores;
the injection of polymers; and
the applicationiof advanced wellfield patiern design and! operation
to increase the volume of contaminants swept from the aquifer.
Of these technologies, the application of advanced wellfield design and us-
ing surfactants are most promising. The U.S. Environmental Protection
Agency (US EPA) noted that "surfactant-enhanced subsurface remediation
was identified as a promising technology for expediting source-zone treat-
ment" (Sabatini et al. 1995).
|
In the petroleum industry, the concentrations of chemical additives used
are low because of the costs involved in oil recovery. The use of surfactant
is a once-through process and it is common to inject as little as 10% of the
pore volume with a 3% surfactant solution (an overall 0.3% solution of the
voliime of the oil reservoir). A ton of reservoir rock from an oil-bearing
formation may contain 80 L (1/2 barrel) of recoverable oil at a selling price
of $0.11/L($17/barrel). The same amount of oil dispersed in an aquifer
may require thousands of dollars to remove because, as noted by Pope and
6.2
-------
Chapter 6
Wade (1995), waste cleanup requires the injection of multiple pore volumes
accompanied by recycling to recover as nearly as possible 100% of the or-
ganic contaminants. Clearly, the economics of aquifer cleanup are quite
different from oil recovery.
Surfactant treatment using continuous injection of a high-strength house-
hold surfactant solution (a dishwashing liquid) in concentrations greater than
0.3% can dramatically reduce the number of pore volumes required to clean
an aquifer compared to standard pump-and-treat techniques. A recent study
compared a surfactant enhanced flushing to water flusMng for the removal of
trichloroethylene (TCE)(McKee and Way 1994). With water alone, it was
found that almost 50% of the TCE remained in the soil with no notable de-
cline after 25 pore volumes of flushing. This occurred because a portion of
the waste is held in the pores between the soil grains by capillary forces and
dissolves slowly into the groundwater. With surfactant flushing, the TCE
contaminant was dissolved at a much higher rate and fl ushed out to near zero
concentration in fewer than four pore volumes. In practice, the surfactant
concentration used will be somewhere between these VNO extremes, 0 and
3%, and foaming agents found in household products can be eliminated in
site remediation applications.
In situ mining technologies for extracting uranium from deposits in aqui-
fers developed on a large-scale in the 1970s have promise for groundwater
cleanup. This technology uses oil-field well patterns with various chemical
solutions. Circulation rates in the largest wellfields reached 40,000 L/min
(10,000 gal/min), and extracted over a 450,000 kg (1 million Ib) of uranium
per year. These techniques have also been used to restore groundwater qual-
ity after in situ solution mining and have promise for in situ cleanup of ra-
dioactive waste sites.
The methods used in the petroleum and solution mining industries can be
compared to the conventional pump-and-treat methods of soil remediation
by graphically projecting the performance of each approach over time. In
the examples which follow, a simple exponential model described by Zheng,
Bennett, and Andrews (1992) generally reflects the performance of many of
the processes used to extract materials from the ground.
Figure 6.1 illustrates the recovery rate achieved in a uranium solution
mining project in Wyoming that operated for 1 2/3 yeairs to extract 124,100
kg (273,700 Ib) of uranium, about 77% of the reserves. The point at which
solution mining of uranium is no longer economically feasible occurs at
-------
about 80% recovery and takes 35 to 40 pore volumes of treatment. In the
Wyoming project, the exponential model closely fit the pnxiuction data and
can be used to forecast the time rgquired for additional uranium extraction
beyond economic recovery. Recovering 90% of thes uranium would take 33
years of operation (about 70 pore volumes} and recovering 99 9% would
take 12.7 years (about 274 pore volumes). As shown in Figure 6.1, the
present-worth costs of the operation range from $3.0 million to $9.5 million.
'i 1
. ,'i I1,.I' Mil;' i, r
,.' '. , , Figure6.1
Projection of Uranium Solution Mining Beyond the Economic Cutoff
: " . '"1,'"'".IT' ' .. ,["'ป, 4 i ' i1'
' ,-. , ,, ' , ,.': , '.! S";,; ,. ! T.' I',. - VI' .
. .. : .. ...i.. , Time(yr)
6 2 4 68 10
.
'$4.0 million
' $3.0 million
50 100 150 200
Estimated Pore Volumes Treated
12
T$9.5 million
250
300
Uranium Initially In place: 124,100 kg (273,700 Ib)
Time to reach S9.9% recovery: 12.4 yr, 274 pora volumes
Remaining after 99.9% recovery: 6ppm
Source: NRC1994
The NRC presented a hypothetical case that illustrates soil remediation by
purap-and-treat methods (NRC 1994). This conceptual example reflects the
treatment of approximately 912 kg (2,011 Ib) of DNAPLs in the water and
6.4
-------
Chapter 6
on the soil. As shown in Figure 6.2, recovery of 80% to 99.9% of the mate-
rial took from 15 to 63 years, at present-worth costs ranging from $2.8 mil-
lion to $5.6 million.
Figure 6.2
Projection of Enhanced Performance with Improved Techniques
Compared to Performance of Pump-and-Treat Methods
Time (yr)
0 10 20 30 ' 40 ' .
1UU
90
80
70
g
$ 60
1 50
| 40
* 30
20
10
0
/$93l,000
/ ....--$3.25 million '
g/$667,000 $2.'8 million
8 ..'' i
i x'' '
* "^ *'
IU .*'
- S NRCCase
'I /
' /
V
, , ,
) 10 20 30 40 50
Pore Volumes Treated
DNAPU Initially In place: 912 kg (2.011 Ib) ; ^
Time to reach 99.9% recovery: No enhancement63 yr; Five-fold enhancement -r-12.5 yr
Remaining after 99.9% recovery: 0.005 ppm i
Source: NRG 1994
Application of solution mining or oil field experience, which includes
optimizing wellfield patterns, might achieve a two-fold, five-fold, or greater
increase in the rate of ckculation in the ground which would, in turn, reduce
the time required to recover material. Shortening the treatment time would
substantially reduce the costs, particularly for recovery above 90%. The effect
of a five-fold enhancement shown in Figure 6.2 is an illustration that does not
-------
(I' n ll i1
.'!'!' 'It
account for the extra costs special treatment would require. The actual costs to
achieve the enhanced performance would be more than those shown.
i111'1 ' t ,' j ''" /, " ,,"/, '{'I!, ' iigjiIF , ", , ,1, ill" i1,!11'",;j"!"' is11;, ,i . ,,,; i* , i',,,,,, Vi ;
Treating the aquifer in the NRCJ example with an appropriate surfactant
could greatly increase the sbtubiiization of the lbl>TAPLฃ A five-fold in-
crease in solubilization by surfactant addition would produce a correspond-
ing five-fold decrease in the number of pore volumes needed to reach any
specified level of recovery. Laboratory experiments suggest that surfactant
addition could bring about a ten-fold or greater improvement in solubiliza-
tion of many contaminants.
The combination of surfactant addition and increased circulation could
potentially create a ten-fold to twenty-fold efficiency improvement in con-
taminant recovery as compared to conventional pump-and-treat technology.
.
:,; IS
:, '; ;!> ri'i'tjj,,- f flgure'6.3
Projection of Enhanced Pump-and-Treat Contaminant Recovery
Performance with Improved Circulation and Surfactant Addition
10
,V'"|!'i,, ^ ^ '.:.:
:.;%'-m I--,, 30
40
ipq
80
70
ง 60
""ซ 50
i **
^ 30
20
"
ฐ<
^ 1 1 1 i
TAventy-Fbld Enhancement
'Ten-Fold Enhancement
/ NRC Base'Case
''< /
/
1 /
/
V .
> 10 20 30 40 5
Pore Volumes Treated
3
DNAPLs Initially In place: 912 kg (2,011 Ib)
Time to reach 99.9% recovery: No enhancement63 yr; Ten-told anhancement6.3 yr; Twenty-fold enhancement3.2 yt
Remaining after 99.9% recovery: 0.005 ppm
Source: NRC 1994
6.6
-------
Chapter 6
Projection of contaminant recovery times with these soil flushing techniques
is compared to the NRC example in Figure 6.3. Reducing the time neces-
sary to reach 99.9% recovery from more than 40 years to less than 10 years
would dramatically affect project costs.
I
Krebs-Yuill et al. (1995) discussed a situation involving large amounts of
DNAPLs, a total of 7 million kg (15.4 million Ib). With the use of surfac-
tant, about 96% of the contaminants were recovered in 7 years. Figure 6.4
compares this surfactant-enhanced treatment using data derived from the
exponential model with conventional pump-and-treat technology experience.
The figure illustrates the benefit of using surfactants to remove such a large
amount of DNAPLs.
Figure 6.4
Projected Performance of Surfactant-Enhanced
Pump-and-Treat Methods Compared to Conventional
Methods for Removal of a Large Amount of DNAPLs
100
90
so
70
60
50
40
30
20
10
0
Surfactant-Enhanced Pump-and-Treat
Conventional Pump-and-Treat
30
60
Pore Volumes Treated
90
120
DNAPLs Initially In place: 57 million kg (15.4 million Ib)
Time to reach 99.9% recovery: 14.8yr, 120 pore volumes
Remaining after 99.9% recovery: 190 ppm
Source: NRC 1994
-------
In iniiiH i nil
Appncanon concepts
Figure 6.5 provides a comparison of the cost effectiveness of conventional
pump-and-treat methods and other processes that involve the use of chemi-
cals and optimization of circulation.
* 'If!1'. !,. I ill
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din, "f L, I Jr.
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Figure 6.5
Cost Comparison of Conventional Pump-and-Treat
Methods to Other Available Technology
10,000
80 90 99.9
Percent Recovered
i ' ""-' '. I ' '"
" Conventional purnp-and-treat
WO In-situ solution mine
i Surfactant-enhanced pump-and-treat
111 1H! '. ' ''I
t f'. ' ! '"
111 If,,. i H. "i
6.2 Scientific Principles
In situ soil flushing is generally used in conjunction with other treatment
technologies, such as activated carbon, biodegradation, or chemical precipi-
tation, which are used to treat contaminated groundwater that results from
'i/i',' 6-8
'::'"!'l 'i ป '.
-------
Chapter 6
the soil flushing process. In some cases, the process cian reduce contaminant
concentrations in the soil to acceptable levels and may be the only soil treat-
ment technology needed. In other cases, in situ biodegradation or other in
situ technologies can be used in conjunction with soil flushing to achieve
desired remediation objectives. In general, soil flushing is effective on
coarse sand and gravel contaminated with a wide range of organic, inorr
ganic, 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-alone technology (US EPA 1991).
Figure 6.6 presents a general schematic of the soil flushing process (US
EPA 1991). The flushing fluid is applied to the contaminated soil by subsur-
face injection wells, shallow infiltration galleries, surface flooding, or above-
ground sprayers.
Figure 6.6
Schematic of Soil Flushing System
Spray Application
Water
Table
Leachate
Collection
Groundwater
Zone
Low Permeability Zone
-------
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i ;.'.. . "I . . i" . <.! 'ซ. . . . , .MI :. "i,11,.: :,; i ,- I <'
I 'I: :i i !:, -il . ...;. ",' ,,;'! .. M .. '-.j: 'i,,,,,.' iii, .'.i ป> |,
Application uonceprs
Soil flushing techniques used to mobilize contaminants are classified as
conventional and unconventional (innovative). Conventional techniques are
further classified as:
natural restoration;
I ''' , ! ', 1, ' ,' , - .. '". ',';'.' ;.' " ' !r(:f."' ... I,i! t.'.'ir, ,- . . ,1 ,.,
1 well-and-capture methods in the vadose zone; and
pump-and-treat systems in the saturated zone.
Innovative techniques consist of primary, secondary, and tertiary recovery
techniques. Primary recovery encompasses, among other methods, neutral
water drrve and gravity drainage. Secondary recovery involves water flood-
ing and pressure maintenance methods. Tertiary recovery employs gaseous
and chemical processes and thermal methods.
The contaminants in the soil determine the type of flushing solution
needed in the treatment process. Examples of three types of fluids are: (1)
water only; (2) water plus additives such as acids (low pH), bases (high pH),
or surfactants (e.g., detergents); and (3) organic solvents (US EPA 1992).
Water is usedStp treat contaminants faa.t are water-soluble or water-mo-
bile, such as inorganic salts of sulfates and chlorides. Acidic solutions are
used to remoye inorganic metal salts, such as carbonates or nickel, zinc, and
copper, as typically found at sites engaged in battery recycling or industrial
chrome plating. Basic solutions are used to treat phenols and certain metal
species, such as zinc, tin, or lead. Surfactants can operate as detergents or as
emulsifiers which can join substances that normally do not mix, such as oil
and water. Surfactant solutions are effective at removing hydrophobic, im-
miscible organic contaminants, such as oil. Organic solvents are used to
dissolve^contaminants that water cannot They are used to remove nonaque-
ous phase liquids (NAPLs).
The efficiency of soil flushing is related to two factors: (1) the increased
hydraulic conductivity mat accompanies ah increase in water content of
unsaturated soil and (2) the treatment solution selected based on the corhpo-
.III1.. I .|. " ..'. ' ... :.l . ....>!,,i ' .....i ii. il h .. i , |i, r, ,
sition of the contaminants and the contaminated medium (Table 6.1). As
shown in Figure 6.7, the hydraulic conductivity of soils decreases markedly
with decreasing water content; therefore, the flow of liquids through unsatur-
ated soils is extremely slow andthe recovery of contaminants by
6.10
-------
Chapter 6
conventional pumping techniques is not possible. With soil flushing, the
water content and, consequently, the hydraulic conductivity of the soil is
increased (Murdoch et al. 1990). However, heterogeneities in soil perme-
ability may result in incomplete removal of contaminants.
The flushing fluid percolates through the contaminated soil removing
contaminants as it proceeds. Contaminants are mobilized by solubilization
into the flushing fluid, by the formation of emulsions, or through chemical
reactions with the flushing fluid (Jin et al. 1994). Contaminated flushing
fluid (or leachate) mixes with groundwater and is collected for treatment.
Ditches open to the surface, subsurface collection driiins, or groundwater
recovery wells may be used to collect flushing fluids and mobilized contami-
nants. The flushing fluid delivery and the groundwater extraction systems
are designed to optimize contaminant recovery. Proper design of the fluid
recovery system is very important to a successful soil flushing program. In
situ solution mining of uranium and copper is common and offers proven
methods for circulating chemicals in the ground to remove target materials.
The petroleum industry also has developed effective means to maximize
fluid movement in soils.
Contaminated groundwater and flushing fluids, typically water or water
with additives, are captured and pumped to the surface from the fluid recov-
ery system. The rate of groundwater withdrawal is determined by the flush-
ing fluid delivery rate, the natural infiltration rate, and the groundwater hy-
drology. These factors will determine 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 of the remediation site is maintained.
The extracted groundwater and flushing fluid are Heated using the appro-
priate wastewater treatment methods to reduce its heavy metal content, or- ,
ganics content, total suspended solids, and other parameters until it meets
regulatory requirements. Metals may be removed by lime precipitation or by
other technologies compatible with the flushing reagents used. Organics are
removed with activated carbon, air stripping, or othei
gies. Whenever possible, treated water should be recycled as makeup water
to the front end of the soil flushing process.
appropriate technolo-
-------
_ =_ -==--
lip
i
!|
ro
Table 6.1
Soil Rushing Critical Factors and Conditions
Factor Influencing Technology Selection
Conditions Favoring Selection
of In Situ Treatment
Basis
Data Needs
Equilibrium Partitioning of Contaminant
Between Soil and Extraction Fluid"
Complex Waste Mixture*
Soil-Specific Surface Area*
Contaminant Solubility in Water*
Octanol/Water Partitioning Coefficient*
Spatial Variation in Waste Composition*
Hydraulic Conductivity*
No action levels specified
No action levels specified
1,000 mg/L
Between 10 and 1,000
No action levels specified
> 10'3 cm/sec
ป Contaminant preference to partition to the
extractant is desirable
High partitioning of contaminant into the
extortion fluid decreases fluid volumes
Complex mixtures increase difficulty in
formulation of a suitable extraction fluid
High surface area increases sorption on soil
Soluble compounds can be removed by
water flushing
Very soluble compounds tend to be
removed by natural processes
More hydrophilic compounds are amenable
to removal by water-based flushing fluids
Changes in waste composition may require
reformulation of extraction fluid
Good conductivity allows efficient delivery
of flushing fluid
Equilibrium partitioning
coefficient
Contaminant composition
Specific surface area of soil
Contaminant solubility
Octanol/water partitioning
coefficient
Statistical sampling of
contaminated volume
Hydrogeologic flow regime
m
ง
S
o
I
-------
Clay Content*
Cation Exchange Capacity*
Flushing Fluid Characteristics*
Soil Total Organic Carbon Content
Contaminant Vapor Pressure
Fluid Viscosity
Organic Contaminant Density
No action levels specified
No action levels specified
Fluid should have low toxicity,
low cost, and allow for
treatment and reuse
Fluid should not plug or have
other adverse effects on the
soil
< 1% (by weight)
< 10 mm Hg
< 2 centipoise (cP)
> 2 g/cm3
Low clay content is desirable
Presence of clay increases sorption and
inhibits contaminant removal
Low cation exchange capacity is desirable
Cation exchange capacity increases
sorption and inhibits contaminant removal
Toxicity increases health risks and
increases regulatory compliance costs
Expensive or non-reusable fluid increases
costs
If the fluid adheres to the soil or causes
precipitate formation, conductivity may
drop, making continued treatment difficult
Soil flushing typically is more effective
with lower soil organic concentrations
Volatile compounds tend to partition to the
vapor phase
Lower-viscosity fluids flow through the soil
more easily
Dense insoluble organic fluids can be
displaced and collected by soil flushing
Soil composition
Soil color
Soil texture
Cation exchange capacity
Fluid characterization
Bench- and pilot-scale testing
Total organic carbon content
of soil
Contaminant vapor pressure at
operating temperature
Fluid viscosity at operating
temperature
Contaminant density at
operating temperature
'Indicates higher-priority factors
Source: US EPA 1993
o
-------
Figure 6.7
Hydraulic Conductivity vs. Tension for
Berino Loamy Fine Sand and Glendale Clay Loam
1,000
I
10
0.1
0.001
>Berino
Glendale
10 100 1,000 10,000
Tension (cm)
6.3 Potential Applications
i
A number of chemical contaminants can be removed from soils using soil
flushing (Table 6.2). Soluble (hydrophilic) organic contaminants are often
easily removed from soil by flushing with water alone. Typically, organics
with octanol/water partition coefficients (Kqw) less than 10 (log Kow
-------
Chapter 6
Table 6.2
Applications of Soil Flushing on General Contaminant Groups
Contaminant Groups Effectiveness
Organic
Halogenated Volatiles
Halogenated Semivolatiles A
Nonhalogenated Volatiles A
Nonhalogenated Semivolatiles *
PCBs A
Pesticides (halogenated) ^
Dioxins/Furans A
Organic Cyanides ^
Organic Corrosives A
Inorganic
Volatile. Metals A
Nonvolatile Metals i"
Asbestos *
Radioactive Materials ^
Inorganic Corrosives A
Inorganic Cyanides A
Reactive
Oxidizers A
Reducers ^
Demonstrated Effectiveness: Successful treatabllity test at some scale completed.
A Potential Effectiveness: Expert opinion that technology will work.
No Expected Effectiveness: Expert opinion that technology will not work.
Source: US EPA 1993
-------
inorganic metal salts, such as carbonates of nickel, zinc, and copper can be
flushed from the soil with dilute acid solutions. Some inorganic salts, such
as sulfates and chlorides, can be flushed with water alone.
In situ soil flushing has been used for treating soils contaminated with
hazardous wastes, including pentachlorophenol and creosote from wood-
preserving operations, organic solvents, cyanides and heavy metals from
electroplating residues, heavy metals from some paint sludges, organic
chemical production residues, pesticides arid pesticide production residues,
and petroleum/oil residues.
Table 6.3 lists some Superfund sites where in situ soil flushing has been
selected as a treatment method. The table jists current sites, their location,
the types of contaminants requiring treatment, and the status of each project.
6.4 Limitations
!
Studies of the effectiveness of pump-and-treat technology in groundwater
restoration have been conducted by Keeley in 1989, Haley in 1991 and
Palmer in 1992, and discussed in Sabatini et al. (1995). These studies indi-
cate that pump-and-treat technology can intercept and contain waste plumes,
but is incapable of cleaning up the waste with high adsorbing characteristics
in a reasonable amount of time. The uncertainty about cleanup time is a
major concern because it greatly affects the cost of remediation.
In 1994, the NRC reviewed the status of groundwater cleanup and identified
several limitations that largely pertain to current industry pump-and-treat expe-
rience (MacDonald and Kavanaugh 1994) which are also relevent to soil flush-
ing. These and other limitations are discussed in this section.
6.4.1 Physical Heterogeneity
The earth's subsurface is highly heterogeneous. Groundwater is stored in
aquifers consisting of layers of sand, gravel, and rock, each having vastly
different properties. Because of this geologic variability, determining the
pathways by which contaminants spread is very difficult, complicating the
design of cleanup systems.
6.16
-------
Site
Byron Barrel & Drum
Hooker Chemical/Ruco
Polymer, Site OU1
Peak Oil/Bay Drum
Pester Refinery Company
South Calvacale Street
Ortnet Corporation
Vineland Chemical
Montana Pole and
Treating Plant
Jadco-Hughes
Lee Chemical
Lipari Landfill
Rasmussen's Dump
umauua Army uepoi
(Lagoons)
United Chrome Products
U.S. Naval Submarine
Base
Ninth Avenue Dump
Source: US EPA 1996
Soil
Location
Genesee County, NY
Hicksville, NY
Tampa, FL
El Dorado, KS
Houston, TX
Hannibal, OH
Vineland, NJ
Butte, MT
North Carolina
Liberty, MO
Pitman, NJ
Glen Oak Township, MI
Hermistan, UK
Corvallis, OR
Bangor, WA
Gary, IN
Table 6.3
Flushing Applications at Superfund Sites
Primary Contaminants
VOCs (BTX, PCE, and TCE)
VOCs (PCE and TCE), Glycols
VOCs (PCE), BTEX, Metals (Chromium, Lead, Zinc)
PAHs
PAHs
Organic Cyanide
Arsenic and VOCs (Dichloromethane)
VOCs and SVOCs
Solvents
VOCs (TCE)
VOCs, Metals (Chromium, Lead, Nickel, Mercury) Phenol
Benzene and Vinyl Chloride
Explosives (KDX and TNB)
Chromium
Explosives (RDX and TNT)
VOCs (BTEX, TCE), PAHs, Phenols, Lead, PCBs, and
Total Metals
Status
Pre-design: Evaluating alternatives
Pre-design
Pre-design: In negotiation
Pre-design
Pre-design: Considering
bioremediation alternatives
Design
Design: Project on-hold
Being Installed
Installed
Operational: May 1994
Operational
Operational
Operational
Operational: August 1982
Operational: June 199S
Completed: Operational, February
1992 to March 1994
O
Q
TJ
I
O
-------
'; !
1 .',! : i I
"KMI"1! : :
r
: 'iiilii "'"iiiliii'f! ni
I" ;;
i '-,
Ill, '."
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f ,,:ซ
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JF r.t
Solutions to some heterogeneity problems have been developed in the petro-
leum and in situ solution raining industries. The uranium in situ solution min-
ing industry applied technology from the petroleum industry and hydrologic
disciplines, adapting it to site-specific conditions associated with beach sands,
barrier-bar marine sands, braided stream channels with clay, ancient river deltas,
aiuj fault zones. In-fill drilling, for example, has been used as a means of gain-
ing access to oil in heterogeneous zones that are not well connected. Monitor-
ing water levels in the weUfield to balance flow rates and optimize sweep effi-
ciency is another method to handle heterogeneities.
6.4.2 Nonaqueous-Phase Liquids (NAPLs)
are common groundwater contaminants that, like oil, do not dis-
solve readily in water. Lighl nonaqueous-phase liquids (LNAJPLs), such as
gasoline are less dense than water, whereas dense nonaqueous-phase liquids
(DNAPLs), such as the common contaminant solvent trichloroethylene
(TCE), are more dense than water. As an NAPL moves underground, it
leaves small immobile globules trapped in the porous materials of the sub-
iurface. These globules cannot be easily removed with conventional ground-
water cleanup systems. Nevertheless, even with their low solubility con-
taminants continued to mobilize into the groundwater system.
!'-, !" ..... 'l",M i.1 i,,. '!' ; . " ; "' i'r'VS;, ,' ฃ;,<>; ;'", '
-------
Chapter 6
carbon tetrachloride concentrations dropped from 1,000 mg/L to 10 mg/L
after only three pore volumes. Other field trials of interest are being headed
by Sabatini at the University of Oklahoma, and Fountiiin through the State
University of New York (Fountain et al. 1995).
6.4.3 Diffusion of Contaminants into Inaccessible Regions
Contaminants may diffuse into very small pore spaces in the geologic forma-
tions of the aquifer. These small pores are difficult to flush with conventional
groundwater cleanup systems. At the same time, contaminants in the pores can
serve as long-term sources of pollution as they slowly diffuse from the pores
when contaminant concentration in the groundwater decreases.
Potassium chloride has been used in the uranium industries to shrink the
most troublesome smectite clays. Polyelectrolytes have also been used in
the uranium industry to prevent clay migration and pore plugging and to
maintain accessibility to the well bore (Stover and McKee 1995).
Surfactants are another possible means of gaining access to regions of
lower permeability. Fountain et al. (1995) expressed concern that surface
tension reduction of 100- to 10,000-fold "may allow E>NAPLs to penetrate
fine-grained layers that previously acted as barriers." The potential for sur-
factants to penetrate low-permeability areas requkes site-specific laboratory
and field studies before implementing this method.
Hydraulic fracturing has also been to improve accessibility in the oil and
in situ uranium wellfields, and most recently, in waste cleanup (Stover and
McKee 1995). In the extreme, explosives have also been used to improve
accessibility in fractured media (Nichols 1992; Dorrier and Green 1993).
Over-reaming of wells was used in the uranium industry to improve access
of the formation to the well bore.
6.4.4 Sorption
Many common contaminants adhere to solid materials in the subsurface
by chemical attraction or reactions. If a contaminant sorbs strongly to the
aquifer solids, it is difficult to flush out.
Sorption depends upon the composition of the solid and the liquid.
Changing the composition of the liquid by chemical additives can alter the
sorption properties of the solid. For example, during the restoration of an
-------
, "'< : i' ป
-------
Chapter 6
elsewhere (NRC 1994). This limitation is of particular concern to regulators.
Effective site characterization and properly designed hydraulic controls or
other containment mechanisms are essential to prevent flushing from spread-
ing, rather than capturing the contaminant(s). i
6.4.7 Innovative Technologies
As the NRC (1994) noted, "a variety of barriers have discouraged those
involved in groundwater cleanup from assuming the risks associated with
using innovative technologies that lack proven track records." The most
significant barriers include the following:
allocation of liability if a technology fails;
inability to raise sufficient capital for successful commercialization;
lack of vendors for some innovations;
federal regulations specifying that any contractor involved in the
selection or testing of a technology is ineligible for construction;
lack of testing facilities;
lack of cost and efficiency information;
lack of adequate technical expertise among consultants and regu-
lators; and
the requirement to construct a pump-and-treat system if the inno-
vative technology fails to achieve cleanup goals.
While the US EPA, DOE, U.S. Department of Defense (DoD), and others
are implementing programs to remove these barriers, the cumulative effec-
tiveness of these efforts is unknown.
6.5 Treatment Trains
Treatment trains used in soil flushing are intended to make the target
contaminants less toxic. In areas of high contaminant concentrations and
deep vadose zones with no recharge, there may be value in diluting the con-
tamination over a vertical profile to reduce surface impact or to allow intrin-
sic remediation to take place. In some cases, biological processes may be
used as a polishing step to remove contaminants whose toxic effects have
been reduced by the flushing action. When biological processes are used
-------
' i, i; u
Si, i : I'll
Hi-
I !
: iij
11 .,/ :.:,: i .Will
Application Concepts
1 : ', , . . ' , i;:": LI , PF I i , :', ' -W !l .ISii, i '.
either during or after soil flushing, the effect of the flushing solution on the
bacteria must be understood.
Bioremediation involves the delivery of required nutrients, co-oxidation
substrates, electron acceptors, or other necessary enhancers of microbial
growth. Various delivery techniques are used to add the required materials to
the subsurfaceenvironment to enhance in situ bioremediation. Application
methods consist of both surface and subsurface spreading.
Surface application methods include flooding, ponding, and the use of
ditches or sprinkler systems. These methods are generally suitable for contami-
nation at depths less than 4.6 m (15 ft). Flooding may be used at sites mat are
flat or gently sloped (i.e., less than 3% slope), have a uniform contour without
gullies or ridges, and contain soils with high hydraulic conductivites (i.e., >10'3
cm/sec, such as those found in sands, loamy sands, and sandy loams). Ponding
can be used in sandy or loamy soils and in flat areas to increase the infiltra-
tion rate of the applied solution as compared to flooding. The depth of the
solution in the ponldrives me JGocnasei in infiltration rates. The ditch method
of surface spreading uses flat-bottomed, shallow, narrow ditches to transport the
solution over the land surface. The solution infiltrates the soil through the bot-
tom and side surfaces of the ditch. Ditches are used at sites where it is best not
to completely cover an entire area with the solution. Sprinkler systems can be
used to deliver solutions uniformly and directly to the ground surface. These
systems are less susceptible to topographical constraints man flooding and
ponding. Sprinkler systems have been used successfully to deliver nutrients
and moisture to bioventing systems where the site was contaminated to a
depth of 15.3 m (50 ft).
Subsurface gravity delivery systems include infiltration galleries (or
trenches) and infiltration beds. These systems are applicable at sites where
there is deep contamination or where the surface layers have low permeabil-
ity. Subsurface systems consist of excavations filled with a porous medium
(e.g., coarse sands or gravels) that distribute solutions to the contaminated
area.' An infiltration gallery consists of a pit or pores through which the
solution is distributed to the surrounding soils in both the vertical and hori-
zontal directions.
Forced systems are another subsurface delivery system. They deliver
fluids under pressure into a contaminated area through open-end or slotted
vertical or horizontal pipes placed to deliver the solution to the zone
requiring treatment (Amdurer etal. 1986). These systems are generally
6.22
-------
Chapter 6
applicable to soils, with hydraulic conductivities >10Jt cm/sec (i.e., the fine
sandy or coarse silty materials) and high effective porosities (i.e., ranging
from 25 to 55%). A maximum injection pressure must be established to
prevent hydraulic fracturing and uplift in the subsurface which would cause
the fluid to travel upward rather than through the contaminated area. Unlike
gravity systems, a forced-delivery system is theoretically independent of
surface topography. Design considerations for gravity and forced delivery
systems are presented in Amdurer et al. (1986). Innovative injection and
extraction systems (as shown in Figures 6.8 and 6.9) have been developed by
Horizontal Technologies, Inc., of Cape Coral, Florida.
For additional information on Bioremediation refer to Ward (1995) and
Dupont (1998).
-------
Fli'i ' ! J '"-
rr
: I
r if1;; r !,"i , i,; ,;#*
i-M "set iff .' f; if1
I !lh:, /!' :! i;" 1 ".'!!::
, ',, "' ,,;,,, ; Figure6.8
Horizontal Wells Used In Soil Flushing
' 1 "'" ' ' : 1' '''
Adjusting Valve
Reversable Flowmeter and Totalizer
Sample Port
---z=^.~jS-
Static Water Level
vo
L
1 r r f ---.*
l ~"znnrir
i.!.f.!.!.!.!.!.!.;
LL;
iiirHDPE Horizontawel
V
D :ซ c/.hปii.iป en pvr Picปr'
. ^ in. Schedule 80 PVC Riser/. _
. __HTI Adapter Coupling^
l&iiLiljjjmzr
ZETIT
Sand with Occasional Interbedded Shell Layers :
Reproduced courtesy of Horizontal Technologies, Inc.
6.24
111 i,,,,ill Ih1";:"!:: '!:> ' lIEiill .: : "!" l .'I. :.fii ill
-------
Chapter 6
Figure 6.9
Extraction and Injection Horizontal Soil Flushing Wells
11 ill 111 III II
1 1 1 1 1
,*
O Horizontal well valued for extraction
Horizontal well valved for Injection
< Flowpath
Reproduced courtesy of Horizontal Technologies, Inc.
-------
ill
-------
Chapter 7
DESIGN DEVELOPMENT
7.1 Remediation Goals
The goal of remediation is to protect public health arid the environment.
While achieving drinking water standards is typically the primary goal, the
true remediation goal should be determined based on health risk, technology
feasibility, time, cost, government regulations, and site conditions to account
for the variety of dynamics influencing any contaminated site.
The primary federal laws that govern groundwater cleanup are the Re-
source Conservation and Recovery Act (RCRA), the Comprehensive Envi-
ronmental Response, Compensation and Liability Act (CERCLA), the Clean
Water Act, and the Safe Drinking Water Act. Most commonly, groundwater
remediation goals under RCRA and CERCLA are set at the levels of drink-
ing water standards. However, the remediation goal for any given site may
depend on the state in which the site is located and whether it is a RCRA or
CERCLA site.
In addition to the water quality standards defined in various water-usage
categories, the US EPA has established maximum contaminant-level goals
(MCLGs) and maximum contaminant levels (MCLs) for drinking water
supplied by public water agencies. The drinking water standards promul-
gated by the US EPA can be found in many publication!!, such as Contami-
nant Hydrology (Fetter 1993) and Alternatives for Ground Water Cleanup
(NRC 1994). An MCLG is a non-enforceable goal set to prevent known or
anticipated adverse health effects within a wide margin of safety. MCLs,
however, are enforceable standards that take into account water treatment
technologies and costs and are set as close as feasible ten the MCLGs. US
EPA also recognizes that attaining drinking water standards is not always
nrteeililo at r-Artain oitfปc
cp of thf.
limitfltiinns: thllS. thft
-------
ปif "'fill11!1!:!!,,, M"' '!'
ii iiiiiiiiii i I iii | ilium ' in
i mi in i ii mi n 111 innnnnn nlin in mini i i ii||nn
Design Development
may allow the original'goals of drinking water standards to be waived.
However, as of 1994, drinking water standard's' were the criteria at 270 out of
300 Superfund sites (NRC 1994).
There are several feasible alternatives to using drinking water standards as
remediation goals. These include:
Remediation to Background/Detection Limit. This alternative
uses background concentration levels or analytical detection
limits as the groundwater remediation goal.
Remediation to Water-Use Category. This alternative returns the
groundwater quality to its original usage category before the
occurrence 'of grounSwater'^el.'domestic water, water for fish
and aquatic life, water for agriculture, water for livestock, or
water for industry) as the remediation goal.
Remediation to Health-Based Levels. This alternative employs
predetermined water quality standards and disregards site-spe-
cific conditions.
Remediation to Technology-Based Standards. This alternative is
based on the capability of best available technology to destroy or
recover contaminants.
i
Remediation 'to Standards Based on Acceptable. Levels of Risk.
This alternative bases the: remedianWgoal on a pre-determined
acceptable risk of the contaminant left in place following
remediation. The National Cpnfingency Plan specifies an accept-
able range of risk as one chance in 10,000 to one in 1 million (NRC
1994). To datei application of risk levels to establishing cleanup
;;'-!': stondardง fia? yet to occur. "
Remediation goals must also consider the two major factors that affect
remediation success the hydrogeology of the site and the contaminant
chemistry. Table 7.1 examines the relative ease of cleaning up contaminated
groundwater as a function of these two conditions. Sites rated "1" are the
easiest to remediate and those rated "4" are the most difficult. The table
shows that groundwater cleanup is likely to be extremely complex at the
majority of sites (MacDonald and Kavanaugh 1994).
-------
Chapter 7
Regulatory agencies often mandate a particular set of remediation re-
quirements as waste site cleanup goals. These requirements take into ac-
count specific site conditions and the site's specific contaminants. Table 7.2
shows MCLGs, MCLs, and remediation goals for selected remediation
projects. State summaries of soil standards (Judge, Kostecki and Calabrese
1997) provides a summary of the cleanup standards for hydrocarbon con-
taminated soil in various states.
Table 7.1
Relative Ease of Cleaning Up Contaminated Groundwater
Contaminant Chemistty
Mobile,
Dissolved Strongly Sorbed, Strongly Separate Separate
(Degrades/ Mobile, Dissolved Sorbed, Phase Phase
Hydrogeology Volatilizes) Dissolved (Degrades/Volatilizes) Dissolved LNAPL" DNAPL"
Homogeneous,
Single Layer
Homogeneous,
Multiple Layers
Heterogeneous,
Single Layer
Heterogeneous,
Multiple Layers
Fractured
1
1
2
2
3
1-2
1-2
2
2
3
2
2
3
3
3
2-3
2-3
3
' 3
3
2-3
2-3
3
3
4
3
3
4
4
4
The difficulty of cleanup is influenced by the hydrogeologic conditions and contaminant chemistry at a site. The NHC
report classified the relative ease of cleanup as a function of these two conditions on a scale of 1 to 4, where 1 is the
easiest and 4 Ihe most difficult.
The 1-4 scale used in this table should not be viewed as objective and fixed, but as a subjective, flexible method for
evaluating sites. Other factors that influence ease of cleanup, such as the total contaminant mass at a site and the
length of time since it was released, are not shown in this table.
Light nonaqueous-phase liquid
b Dense nonaqueous-phase liquid
Reprinted with permission from MacDonald and Kavanaugh, "Sustainable World Trade: Who Will Pay to Clean Up
Britain's Past?," Environmental Scianca & Technology, Volume 28. Number 8, p 3ซ5A. Copyright 1994 American
Chemical Society.
-------
Ill III 111
iiUl "v!,Id
,, In" fSilS1"
''"Illllll V:: III'
h I'n'llllL'l! ill 1:1 |.
, . "I '.i,:111!
":' "
i i, "
i i n
;" '
,
:, i ;::, ;
Table 7.2
Repudiation Case Studies
' 1 , ': ' '
i ' " ' ;
, Site Name, State
Savannah River Site, SCb
'. " '.:: i ' :
McClellan Air Force Base, CAC
in
MCLG
Contaminants (g/L)*
TCE
PCE
TCA
TCE"1
0
0
200
0
Cis-l,2-DCE TO
" " ;, ! , ''ill'1 ' '1 , ,: , ' J:
i'
Langley Air Force Base, VA11
PCE
TCA
1,2-DCA
Benzene
Toluene
0
.V ,
0
0
1,000
Ethelbenzene 700
' ,;; ;-
Lawrence Livermore National Laboratory, CAd
Xylene
Benzene
10,000
1
Ethelbenzene 700
Twin Cities Army Ammunition Plant, MN"1
' I, '
Verona Wellfield Superfund Site, MId
Xylene
TCE
PCE
1,2-bCE
1,1,1-TCA
10,000
0
0
70
200
Vinyl chloride 0
1,1,2-
: ' ' . " "! ,! '" ::, ' Trichloroethane 3
'"," ' ' "!||
. ' , ; " [ i, "'1 . :l
PCE
i,: , i n
Benzene
0
1 " ' o"
I, , M'1' , ' i v, "ป!; r 'i 'i .:i ir r " " V
11 ' !l -I1:! I'1* ,'' '''I, 1 HIM' 1 " i, , '''1, 'n ' I
Toluene 1,000
ii M i " 'i11 ปn ' 'i!,i i iii ii ' , ' i - i, '" , '"i
Source: Fetter 1993
"Source: U.S. Department of Energy 1994
"Source: U.S. Air Force 1994
MCL
(ga,)'
5
5
200
5
70
5
5 ":
5
5
1,000
700
10,000
5
700
10,000
5
5
70
200
2
5
5
5 :: "
1,000
IN n
Remediation Goal
7 Xs^..',,
s
5
200
Oss
i
Not Applicable
055
; issj; ;
055
1.4
2
1
3
I
680
1,750
5
6.9
70
200
1
1
1
i
i
1
800
"Source: U.S. Environmental Protection Agency 1995
!' I11' t1 i '! . I1 111,:,,
1 Jiljliiil.i,;, I |
iiiiii;:::' i, i. i ."i'
I'11'II ",|!'
llซ| :i; ,.4,
7.4
-------
Chapter 7
7.2 Design Basis
Soil flushing techniques for mobilizing contaminants are considered ei-
ther conventional or innovative. Conventional soil Hushing includes the
following activities:
natural restoration,
i
well-and-capture methods in the vadose zone,
pump-and-treat systems in the saturated zone, and
a combination of pump-and-treat and vadose zone soil flushing.
Innovative soil flushing enhanced recovery includes:
secondary recovery, and
tertiary recovery.
Enhanced recovery methods draw upon the experience of the petroleum
and mining industries for secondary and tertiary recovery techniques to re-
move greater than 90% of the contaminants. Secondary recovery methods
include water flooding and pressure maintenance techniques. Tertiary recov-
ery methods inject materials, such as surfactants, to desorb and/or dissolve
contaminants bound within the soil matrix.
The recovery goal for petroleum and mining operations using enhanced
recovery methods is different than that for remediation processes. In petro-
leum and mining operations, 90% recovery may be considered as sufficient;
while in remediation processes, 99.9% recovery may be needed to satisy
environmental concerns.
Table 7.3 presents a summary of screening criteria for enhanced recovery
methods based on oil properties and reservoir characteristics. Table 7.4
provides a comparative summary of seven enhanced recovery processes used
in the petroleum industry.
7.2.1 Site Characterization
One of the most basic needs of a groundwater remediation program is an
understanding of the site's hydrogeology. This will help determine the water
quality and water quantity characteristics of the formation, the degree of
vulnerability of the formation to contamination at different locations, and the
potential remediation technologies.
-------
IKli!) ''"' Tin ' tiiiil ,[ "!"
The characteristics of the vadose zone play a significant role in the poten-
tial for aquifer contamination. Aquifers overlain by permeable sand are
highly vulnerable to surface contamination. Clay, on die other hand, is
rather impermeable and retards contaminant 'movement,
Understanding the geology, hydrology, and geochemistry of the contami-
nated formation is the first major step in'obtaining the "required information
for remediation design. Knowledge of the characteristics and boundaries of
the aquifers themselves provides important information on the potential
contaminant movement and transport. The flow of groundwater and trans-
port of contaminants are functions of hydraulic gradient, hydraulic conduc-
tivity, effective porosity, and dispersivity which are dictated by the site's
geology and hydrology. Table'7!5 identifies some of the principal types of
information that must be gathered for site characterization.
Site characterization begins with understanding the geohydrology of the
region. Geologic cross-sections prepared from well coring and geophysical
logging information provide an excellent visual presentation of the general
geology and delineation of the target 'area.'"Sebibgic map's," along with water
level information, also furnish information on the recharge and discharge
areas, and the regional groundwater flow. Well logs, water quality data, and
well completion records may be available through federal and state agency
databases. Careful review of these records can yield a general picture of past
hydrologic activities in the site area.
A number of test wells should be drilled, cored, logged, and sampled at
strategic locations to accurately delineate the area of contamination. Geo-
physical surveying may be useful in the study of some subsurface inorganic
contamination distributions, especially where there is a good contrast be-
tween background and anomaly. Two of the most commonly-used geophysi-
cal survey techniques are resistivity and electromagnetic conductivity.
Hydrologic tests are performed to calculate the values of hydrologic
parameters. The first hydrologic test to be performed is the slug test.
By rapidly injecting a constant volume of water into the v/ell and moni-
toring the recovery of the water level, the transmissivity of the formation
can be calculated within reasonable limits. A constant rate single-well
pump test can be performed to ob|ajn Values of transmissivity, hydraulic
conductivity and well efficiency.
-------
Screening
Table 7.3
Criteria for Enhanced
OIL PROPERTIES
Gravity
API
Viscosity
(cp) Composition
Oil
Saturation
GAS INJECTION METHODS
Hydrocarbon > 35
Nitrogen & > 24
Flue Gas >35forN2
Carbon >26
Dioxide
< 10 High % of
Cj-C,
< 10 High % of
f* ./"*
t,2-c,
< 15 High % of
C5.C12
>30%PV
>30%PV
>30%PV
CHEMICAL FLOODING
Surfactant/ > 25
Polymer
Polymer > 25
Alkaline 13-15
<30 Lighter
intermediates
desired
<150 NC
<200 Some
organic acids
> 30% PV
> 10% PV
Mobile oil
Above
waterflood
residual
Recovery Methods
RESERVOIR CHARACTERISTICS
Formation
Type
Net
Thickness
Average
Permeability
Depth
(m)
Depth
(ft) Temperature
Sandstone or
Carbonate
Sandstone or
Carbonate
Sandstone or
Carbonate
Thin
unless
dipping
Thin
unless
dipping
Thin
unless
dipping
NC
NC
NC
600 (LPG)
to 1,500
(HJP.Gas)
> 1,400
>600
2,000 NC
(LPG) to
5,000 (H.P.
Gas)
> 4,500 NC
' > 2,000 NC
Sandstone
preferred
Sandstone
preferred;
Carbonate
possible
Sandstone
preferred
>3 m
(> 10 m)
NC
NC
>0.2 m/sec
(> 20 md)
> 0.1 m/sec
(> 10 md)
normally
>0.2 m/sec
(> 20 md)
< 2,400
< 2,700
< 2,700
< 8,000 <80'C
(< 175'JF)
< 9,000 <94"C
(<200'F)
< 9,000 <94'C
(< 200'F)
O
E
TJ
3
-------
i 1-1 * ("I iซ i '
1 I !j
K
'S!l| Jl II
: "" ;.--"" ^jU'i i >< ir
ar
i '= I VI? sl r f" 311 i ^ i 1 h
__ r ^_ * ! ;_ ^ ^ : ..
ป ;;
;S
." - - t - -"-; :;'"" :-: !
iss! II :;i lp*E Is! I j
!!;!;; 5! III hfii i| ! I
r ;
Table 7.3 cont.
Screening Criteria for Enhanced Recovery Methods
OIL PROPERTIES
; , \
, ;.,u. THERMAL
i 7 : - -'
. Combustion
' ป -:i
: i -^Steam-
-. ;:; Flooding
;
Gravity
API
<40
(10-25
normally)
<25
Viscosity
(cp)
< 1,000
>20
Composition
Some
aspballic
components
NC
Oil
Saturation
> 40-50%
PV
>4O50%
PV
"RESERVOIR CHARACTERISTICS
Formation
Type
Net Average
Thickness Permeability
Depth
(m)
Deoth
(ft)
Temperature
Sand or
Sandstone with
high porosity
Sand or
Sandstone with
high porosity
>3m
(> 10 m)
>6 m
>20m)
> 1.0 m/sec
OlOOmd)'
> 2.0 m/sec
(> 200md)"
>150
90-UOO
>500
300-5,000
>65'C
(> 150'F)
preferred
NC
NC Notcritfca!
cp cenflpoises
md mlllidarcies
TransmfesibiHy *O.OBlnP /sec/cp (or20 cmWI/cp)
"Transmissibiปy>a06/mi!Aec/cp(or20nxHtta))
Should not be taken as absolute values, but as rules of thumb only.
1 J= = - =-- ซP
-*i^
' "
-------
Chapter 7
Table 7.4
Comparative Summary of Petroleum Industry
Enhanced Recovery Processes
Process
Immiscible Gas
Miscible Gas
Polymer
Micellar/Polymer
Alkaline/Polymer
Steam
(drive or soak)
In Situ
Recovery Mechanism
Reduces oil viscosity;
Oil swelling;
Solutions gas drive
Same as immiscible
plus development of
miscible displacement
Increase volumetric
sweep efficiency by
reducing mobility ratio
Same as polymer plus
reduction in IFT forces
Same as micellar/
polymer plus wettability
alteration
Reduces oil viscosity
Vaporization of light
ends
Same as steam plus
cracking of heavy ends
Typical
Recovery
(%)
5-10
5-15
5
15
5
50-65
10-15
Typical Agent
Utilization
0. 18 scM gas/L oil
0.18 scM giis/L oil
1.4-5.7 g polymer/
Loil:
43-71 g surfactant/
Loil
100-128 g
chemical/L oil
0.5 L oil coiisumed/
L oil produced
5-10 L steara/L oil
0.18 scM gas/L oil
Typical Agent
Utilization
10 Mscf gas/bbl oil
lOMscfgas/bbloil
0.5-2 Ib polymer/
bbl oil
15-25 Ib surfactant/
bbl oil
35-45 Ib chemical/
bbl oil
0.5 bbl oil
consumed/bbl oil
produced
5-10 bbl steam/bbl
oil
10 Mscf air/bbl oil
Table 7.5
Site Characterization Information for Remediation Design
Geology
Hydrology
Geochemistry
Geologic cross-sections
Lateral continuity of saturated
zones
Hydraulic communication
between adjacent formations
Recharge areas
Discharge areas
Hydrologic properties of
aquifer
Water level in wells
Wellhead elevations
Dispersivity values
Regional groundwater use
inventory
Adsorption characteristics
Biodegradation information
Primary contamination
migration peak
-------
ii ii i *,, "i in, i1; HI, I.
i PHI I ' "i
ill111 ill"
jili , ft i, *: :
-------
Chapter 7
It is important to make the operation cost-effective through efficient
wellfield design and operation. Figure 7.1 shows hypothetical soil flushing
recovery curves from two different wellfield designs one efficient and one
inefficient.
Figure 7.1
Hypothetical Contaminant Recovery from Two Wellfield
Patterns One Efficient and One Inefficient
Efficient Wellfield Design
Inefficient Wellfield Design
Time
Good wellfield design for in situ soil flushing incorporates the experience
from enhanced oil recovery and in situ mining. Figure 7.2 shows the most
basic wellfield patterns based on that experience (Craig 1971; Muskat 1971).
These patterns are used when the contaminated area extends in all directions.
Special wellfield patterns must be designed and applied when dealing with
odd-shaped contaminated areas.
Table 7.6 presents the ratios of recovery to injection wells and areal
sweep efficiency (the percentage of area contacted by the injected solution at
a given time) at breakthrough in an isotropic homogenous formation for ba-
sic wellfield patterns (Craig 1971; Muskat 1971). For example, Table 7.6
shows areal sweep efficiency at the time of solution breakthrough at the recov-
ery well in isotropic geologic formations. The values shown in Table 7.6 are
-------
I (11<
based on the assumption that very large wellfield patterns have been used. A
range of values is shown for area! sweep efficiency^ Different studies have
1 ' i'l "' I'i IK
.- i; :;-. ' > /'iiii? 'I
obtained different values for sweep efficiency depending on the method of
simulation (Craig 1971; Muskat 1971).
, , , ,"!!,'!','!, "II" 'IS' 1 , 1,,
;.. ;.,,;'. '. . . ..,;"-';'';-:,'r:;".'.~:ia:"
Standard Wellfield
, ' '' " ,. I1-11' ' '">; II1!1 nil"'!" J:till ,,11! HE / ป "PI* '
Patterns
mi. M ' ji
.- t
;
n .-O- -.ฐ ! O..-A-.P ฐ A ฐ/
',.
. .
i' A *i ( A ]
V, / Vo>
Two-Spot Three-Spot
Xoxฐxฐ
- o ''ฃ. 'o X o A
AXo''A'o'''AxO
Rve-Spot
OApAO AOAOA
Q..O-f^-o-6 A"A-A-A-A
O-O-6--O-P A"A"A-A-A
o A 6 A 6 AOAOA
Inverted Nine-Spot Normal Nine-Spot
o.'A-:
.p i o ..:
o/c
V.
X
ii' i
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:;o | o ;:&:; o A--b/o.^;
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Regular Four-Spot
ฃ$ฃ
6
' ;|' :
";;"":::: : :
! ''",!, .I r . lii 'ill i'',;/ 'V '
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W^
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Skewed Four-Spot
6 A- A o-b. A p-o
A-4 o A-A
'. o A'"A o
A-A 0 A-A
Seven-Spot
i
TT1
IT4
. Direct Line Drive
1'
Injactlon well
Production well
Pattern boundary
Raorfnted from Craig, "The Reservoir Engineering Aspects of Waterfloodlng," 1971,
of Petroleum Engineers.
A,
O-Q
A;
o-d
Invertei
o-
-i
o-
-t
o-
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o
w
b-
A
P"
A
iSc
6-
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o
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ven
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O
W
O
^
A
)--0
A
)-O
-Spot
1 w-
ฐf
a
O
i-
Staggered Line Drive
." 11
p 49, with permission of the Society
; - i ซ'! IB , '' iiiiiiii
7.12
-------
Chapter 7
Table 7.6
Ratio of Recovery Wells to Injection Wells and Sweep Efficiency
Wellfield Pattern
Two-spot
Three-spot
Regular four-spot
Skewed four-spot
Five-spot
Direct line drive (d/a =1)*
Staggered line drive (d/a = 1)*
Seven-spot
Inverted seven-spot
Normal nine-spot
Inverted nine-spot
Ratio of Recovery to
Injection Wells
1:1 ,i
2:1
I
2:1
2:1
1:1
1:1
1:1
1/2:1
2:1
2/3:1
3:1
Area! Sweep Efficiency at
Breakthrough (%)
52-54
67-79
73-82
70-80
67-73
55-60
74-78
73-80
73-82
65-80
65-80
a = distance between two adjacent rows of opposite wells; d = distance between two adjacent rows of like wells
Source: Craig 1971
7.3 Design and Equipment Selection
In addition to area! sweep efficiency and breakthrough time, there are
several other controlling factors in soil flushing wellfield design. These
include:
well recovery rate and injectivity,
formation anisotropy,
regional groundwater flow, and
geochemistry and contaminant recovery.
These factors will be discussed in the following sections.
-------
7.3.1 We|l Recovery Rate and Injectivity
Well recovery rate and injectivity provide a good indication of the
type of basic wellfield pattern to be considered. For example, if a well
nl I I | 1 "Mlli: ;|.:!iy 'I: ' ' . . -/.i ; .i" 1.11 . "', MI r.j.'ij i ; 1 I .!.ป:, a .1 ,'. f' ' i,,,-
in an aquifer can produce 190 L/min (50 gal/min), but can only inject 95
L/min (25 gal/min), the optimum wellfield pattern would consist of
twice as many injection wells as recovery wells. Then, by referencing
Table 7.6, a four-spot or seven-spot wellfield pattern should be selected.
Additionally, injectivity and:recovery rate determine the breakthrough
time and economic feasibility of soil flushing. If injectivity and recov-
ery are high, greater well spacing can be used.
Injection pressure should not exceed the pressure at which hydraulic frac-
tures would begin to develop and cause the injection and recovery wells to
short-circuit. On the other hand, the water level in the recovery well should
,' '}'' -'|j ;'"/.'" ' .""- /' not fall below the top of the'''target horizon.
In estimating well pumping and injection rates, well efficiency (safety
factor) should be considered. Wells do not usually operate at 100% effi-
|}|i | I1 ' |)l i ' -. '; ;,,,||!;' iJti} :'!.;,,, J* I-;;;1 ซenpy because of well boKjdi^^emdl'w^^i^nfiugg^g/ln&vid^
j.j "*- i P"'1 , , & !;ซ;ซ !:>: ! "I;"' ". .:'!" ' well efficiency can be calculated from pumping test or slug test data. Wells
;!' I'( ' i!*i; ": '"'" ' . J" It- '!!'! ' '*.'' -' ' if ' >.'-tend iio (Deteriorate during operation and well efficiencies decrease over time.
i.'rij, '""n 'ป, I,,!,, i , i ':||ป ,,;i ''ir'N!1! Jjfa'fl1' ป ! .: '"!'' ' '1'1 ',ป! ' ' ' '" , ^i '"!!, "
':. ",:r .: ;::"";;;,: '" .,:: :::":; :: ;":" '.".'.^ . 7.3.2 Formation
'" i-T1'! ,i
.i.vl'.fli.1
ii,"1.1,!1!!1 i1,, A:!',!' ""'!. i . '" f... a , . . R sfT
meabihty is in the direction parallel to the direction of the fractures. The
directional permeability of a geologic formation and the hydraulic gradient
determine the preferential groundwater flow direction (Darcy's Law).
Boundary conditions dictate the hydraulic gradient. To optimize the areal
coverage, the direction of induced flow should be oriented along the direc-
tion of minor permeability. Figure 7.3 presents two different cases for di-
rect-line-drive well patterns. In Case 1, the direction of minor permeability
is perpendicular to the flow direction, and the areal coverage is small. Case
2 provides better coverage because the direction of minor permeability is
parallel to the induced flow direction.
74
....... iiilii ...... 'iliSilSiiS ...... iiiiittit'iii! ili , ..... ..... I,..!:: ....... Ji": ...... iudliii ........... ;tii^^K.^f!'ฃ!iH'iftHjฃ...*ttซf|: JJI ..... i
-------
Chapter 7
Figure 7.3
Effects of Horizontal Directional Permeability
^.rfv Injection
}
^Production
Case 2
Production ~GIป. "^ Injection Production "o^ \^ Injection
""ininor
7.3.3 Streamlines and Pore Volumes
Before well spacing can be determined, it is necessary to examine how
long the chemicals or nutrients can stay in the ground and how far they can
travel before losing their effectiveness. A laboratory "'stream tube" experi-
ment is instrumental in selecting the proper chemical mix or nutrients (see
Figure 7.4) Applying the results of this experiment should effectively mini-
mize the number of streamline pore volumes to clean up the contaminant.
It is also essential to control the flow pattern in such a way that the break-
through times for all streamlines will be close so that the peak concentration
is high and the recovery time short.
-------
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7.16
I II
-------
Chapter 7
7.4 Process Modifications
After designing the basic soil flushing system, it is appropriate to assess
modifications to enhance the effectiveness of contaminant removal to mini-
mize the time and cost to complete the remediation.
Geochemical procedures for the restoration of groundwater quality are
tested in the laboratory, using beakers or columns and stream tubes, as each
specific situation requires. The various contaminant nscovery techniques
that can be tested in the laboratory include ion exchange, reverse osmosis,
electrolysis, bacteria conversion, and precipitation. Laboratory column tests
also help determine the most suitable chemical (lixiviant), polymers, or sur-
factants for soil flushing.
7.4.1 Laboratory Tests
Batch tests are the simplest form of testing to screen processes for soil
flushing. A contaminated soil sample in a container is saturated with se-
lected solutions (natural groundwater or synthetic water spiked with specific
solutes) and agitated by a shaker or a roller. The liquid samples are collected
and analyzed at predetermined time intervals. The soil sample used in the
batch test should be representative of the site soils. Batch tests should iden-
tify soil flushing processes that will not work in the field.
Column tests provide further screening and optimization of the soil flushing
process. Column leach experiments are usually performed in a vertically ori-
ented glass column. The contaminated soil sample is packed in the column.
The solution (natural groundwater or synthetic water spiked with the solute of
interest) is injected into the column at a predetermined flow rate (upward or
downward flow). Liquid samples are collected at the column outlet. The re-
sults are evaluated to assess the effectiveness of the process. A water treatment
circuit can be added to the testing program to examine the ability to recover
contaminants from the contaminated liquid coming out of the column.
Stream tube tests employ a series of long columns having a variety of
diameters and lengths, depending upon the application,. These tubes should
be sufficiently large to preclude edge effects which could compromise scale-
up calculations. These are interconnected to provide a flow path of up to 60
m (200 ft) or longer, as appropriate, with sampling poits at each juncture
(see Figure 7.4). Stream tube tests require much larger volumes of
-------
II 11(11
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contaminated soil samples, often in the range of several kilograms. The
flushing solution is injected into the stream tube at a predetermined flow
rate. Liquid samples are taken at the sampling ports at predetermined inter-
vals. The contaminant recovery rate of a particular process can be evaluated
as a function of time and distance. The results from stream tube tests reveal
:! i ' , " ' '' I",;!'11, 'i . !!': ""aill1. I'' lin^^^ llllliB^^^ IIIIIRII ilt'iKltt^^^^^ , , tl|!" "" ' '
how long and how far the chemical can travel underground before losing its
leaching ability. This information is essential in determining well spacing
between injection and recovery wells and, subsequently, the cost of the pro-
posed soil flushing remediation program.
7.4.2 Soil Flushing Solutions
Flushing solutions may include water, dilute acids and bases, complexing
and chelating agents, oxidizing and reducing agents, solvents for inorganic
and metal contaminants, or surfactants for organic contaminants. The ideal
flushing solution is inexpensive, common, and nontoxic, that rapidly mobi-
lizes 100% of the target contaminant at low concentrations, releases no haz-
ardous or toxic substances, causes no decrease in formation permeability,
and remains unretarded in its transport through the formation. Chemically
enhanced soil flushing is applicable at many remediation sites with metals or
1";! radioactive material contaminants., r r i t : , , , i ii,ii],iiii ,
It is important to remember that each site is"unique'and eacri contaminant
has its own physical and chemical properties. No single flushing solution
can satisfy all requirements and be effective for all contaminants.
;: ii"11, ;' i, :/ i.: i i,,,: f,i: ",.,.,a*S'K_}' vs. ^^:ปi* " v-ffi f**ซ(ti(j'.
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7.4.2.1 Organic Contaminants
Soil flushing with surfactant solutions to extract hydrophobic organic
contaminants appears to be one of the most promising in situ cleanup tech-
nologies. Aqueous surfactant solutions are superior to water alone in ex-
tracting hydrophobic contaminants. The detergency of aqueous solutions
and the efficiency by which organics are transported by aqueous solutions
are improved by the addition of surfactants. The processes for improving the
detergency of aqueous solutions are preferential wetting, increased contami-
nant solubilization, and enhanced contaminant emulsification (Edwards,
Luthy, and Liu 1991).
The addition of surfactants increases the efficiency by which organics are
transported by the flushing fluid, compared to the injection of water only.
7.18
,i./ if! I4IHI1!: ' .
:i,!'!i,ซt!i Jซ
l!K,;l til!'
iiiiK luiiiia iii>; ii> i niii
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-------
Chapter 7
When only water is injected, contaminants are extremely difficult to remove
because they have become trapped in the pore spaces. Also, flow rates and
pressure gradients in standard pump-and-treat processes may not be high
enough (on the order of hundreds of meters per meter of pressure gradient)
to force immiscible contaminants, such as DNAPLs, through the soil matrix.
With the introduction of surfactants, the interfacial tension of the system is
substantially reduced. Tiny droplets of organics that are surrounded by the
surfactant are subsequently "dissolved" into the water phase and are then
more readily transported through the soil pores. Another reason the use of
surfactants for hi situ soil flushing appears promising is that numerous
environmentally-safe and relatively inexpensive surfactants are readily available
commercially (Edwards, Luthy, and Liu 1991).
The use of surfactants to enhance oil recovery from subsurface oil reser-
voirs has been practiced by the petroleum industry for many years. Research
has recently been conducted on the use of surfactants for soil washing and
soil flushing. Figure 7.5 shows the effectiveness of one surfactant (one
brand of dishwashing liquid) compared to that of water flushing alone in
removing TCE from contaminated sand (McKee and Way 1994). The sur-
factant used in the experiment was injected at a relatively high concentration
that may not be cost-effective in field applications. However, the actual
results of TCE recovery remain consistently higher when flushing is per-
formed with a surfactant solution as compared to water only. Table 7.7
shows the results of several laboratory and field tests using surfactants to
recover contaminants. The results demonstrate that surfactant use dramati-
cally increased the removal of hydrocarbons and chlcdnated hydrocarbons
from contaminated sand. In each of the experiments shown, the recovery of
the organic contaminant increased when high concentrations of surfactant
and/or larger treatment quantities were injected.
Figure 7.6 shows the results of a laboratory experiment testing the recov-
ery of diesel fuel from a coarse-sand soil column (94% <14 mesh) using a
variety of flushing liquids. The first experiment used a 100% dishwahing
liquid. The second used only water (note that the curve is flat after five pore
volumes). The third used a 1% Drispac, an oil field polymer solution. The
100% dishwashing liquid was continually added until all the diesel fuel was
recovered. In the other two tests, only 80% of the diesel fuel was recovered.
The coarse sand retained 20% of the diesel fuel in the pores which is avail-
able to slowly leach out and continue to contaminate the groundwater. As
-------
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"" , '-';;_ " ;; ~ "~ _ ,;_:;_ ; ' J; Pjjie Volume^Injected
, , > , ,, ,
Steam is another soil flushing enhancement that has been used to clean up
organically-contaminated soils. The injection of steam tends to volatilize
and reduce the viscosity of contaminants by increasing their vapor pressure.
This phenomenon, combined with the pressure differential caused by the
steam pressure arid vacuum extraction, increases the mobility of contami-
nants in the media (Noffsinger 1995). In a pilot-scale of steam injection for
soil flushing conducted in California, steam was injected into six wells that
"nil illlllli ill 111 I 111 III III III ill
7.20
IIII I III I II |l III ll|lllll|lllll
I III III III l|l I III III III III
-------
Chapter 7
surrounded a single vacuum recovery well. After a relatively short treatment
time of 140 hours, average contaminant concentrations were reduced by a
factor of 50 in comparison to the standard pump-and-treat method
(Noffsinger 1995).
7.4.2.2 Inorganic Contaminants
Inorganic contaminants can be flushed from soil by chemical solutions or
they can be stabilized in situ by changing them into a form that is not soluble
in posttreatment conditions. For example, uranium readily forms soluble
complexes with bicarbonates, carbonates, and sulfates when it is oxidized to
the hexavalent state. However, uranium in the tetravalent state is not soluble
and will not be transported by water. As water moves through soil, its chem-
istry can be altered by reactions between the components in the water and in
the soil. Understanding and controlling the reactions between the water
(soluble phase) and the soil (insoluble phase) is important for successful
contaminant removal or in situ stabilization.
Contaminants can be flushed from soil and transported in a water-based
solution if the solution chemistry favors the soluble form of the contaminant.
However, if the solution chemistry changes by contact with soil or by
groundwater dilution, it is then possible for some contaminants to precipitate
or be adsorbed from the solution. Many inorganic contaminants are present
in solutions in a soluble form as well as in the soil in an insoluble form. The
amount of contaminant in the solution and soil is controlled by equilibrium
considerations. If the solution containing the contaminaint is removed and
replaced by a similar solution without a contaminant, then a portion of the
remaining contaminant in the soil will dissolve and seek: to establish a new
equilibrium concentration in the water. Hence, repeated flushing is often
needed to extract inorganic contaminants.
Natural groundwater can be either mildly oxidizing or reducing, depend-
ing upon the properties of the soil with which it has come in contact. As soil
composition changes, so do its properties. Typically, the natural movement
of groundwater disperses contaminants into larger volumes of groundwater
and through larger masses of soil, thus reducing the downgradient contami-
nant concentration in solution and in the soil. Natural restoration processes
are useful for low concentrations of inorganic contaminants, but contaminant
confinement and more aggressive flushing is normally required near the
contaminant source.
-------
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'~;V; ; U , ; ~ - ::"' ' ', .; -"
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Table 7.7
Summary of Results from Surfactant Experiments
_
Material/
~ Lab/Field Formation Type Surfactant
- Lab Sand 2% Richonate-YLA and
(large concrete tank) 2% Hyonic PE-90
2% Richonate-YLA and
' 2% Hyonic PE-90
TO 2% Richonate-YLA and
fฐ 2% Hyonic PE-90
Lab (column) 98% Sand Adsee 799 and
-Hyonic PE-90
Lab (beaker) Sandy Soil Water
0.5% Witeonol 1206
0.5% Witeonol SN70
0,5% Witeonol SN90
0.5% Witeonol NP100
0.5% Whcamide 5130
- - 0.5% Adsee 799
0.5% Witcolate D51-51
0.5% Witcolate DS-10
" 0.5% Emphos CS1361
0.5% Witconate AOS
-- i
Number of
Contaminant Pore Volumes * Recovery
Automatic Transmission Fluid (ATF) single application 6
Automatic Transmission Fluid (ATF) multiple (daily) 76
application by
percolation
Automatic Transmission Fluid (ATF) multiple (daily 83
applications by
direct injection into
the water table)
Total Organic Carbon (TOC) 12 50
Volatile Organic Analysis (VOA) 12 99
Biochemical Oxygen Demand 12 50
(BODS)
Automatic Transmission Fluid (ATF) Beaker 22.9
Automatic Transmission Fluid (ATF) Beaker 83.8
Automatic Transmission Fluid (ATF) Beaker 82.2
Automatic Transmission Fluid (ATF) Beaker 81,3
Automatic Transmission Fluid (ATF) Beaker 71.9
Automatic Transmission Fluid (ATF) Beaker 63.4
Automatic Transmission Fluid (ATF) Beaker 33, 1
Automatic Transmission Fluid (ATF) Beaker 81.1
Automatic Transmission Fluid (ATF) Beaker 63.4
Automatic Transmission Fluid (ATF) Beaker 56.7
Automatic Transmission Fluid (ATF) Beaker 71.0
" ! I! ! !!ซ i i I 1
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_ = __ !! T S ^ . s = - - S. * i T .. -^^=-= i-rJFt"i=s " = P M -
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= -_- :---=- = . - - i --4 .= = = -
- V^ ,V'-: VV ? =E ~* -i- - " =
- -- : ir - ^^P.:! -^i^-i' ^ ; i
.! s= : _=*^ - =- -=^- --"= " =;=-." " !! s
---=--- S5 := . -
'^ III L , ^m ^ =-i. -=iii-i - mi=-^w-^-/~ li : ^i = : = S
=. - _ = = = =-;.= = =tf.k .=^^5== = = = =<=_ -j= f s ;= s =s =
i = ---?=_-"-=ป!: -^i = - - ii =
= j s li i I i
.- . - =_" L = : ; . i :
=- : "-'_-*";
',ซซ>
J 4 H a ป ,;
"; J: :-,_-, : ' i
,1 , : --- -'-,,, , -- :
- ' - ; : ^" - - _-'--" '--"
:-"- = ' -*--.- "-' ^-,-i-:- - ' - --
- ; -:1 '-" ?" ^;
-- |( '- ซ i = ซs- ' Vx .--^ii^' : iilr
^ :; : : iซ;::'*!1iซtr:-v;::^r-
-"-:-r-: ' : ~:.; .
--J i ^ v- ?! *iซ i J' .
T = - = J ^^ ^= = -- " ? =
-=^ . :-, ;- _ = -^i _
- - - =" -;CT=J --= : -rj=- - .
s t: =v-- *si J*? -', - -,_. .1 -- ; =-
i = ฃ=__./ iii;Pฃ:- :-^ ^ ^ :
Reference H ! - S
; _ "2 --: - 5?= i^^gr^,; := =
American Petroleum ; ' " J- :-"-- ";""! i;-.;"""- " i.
Institute 1985 M ' * S :!i i
1' i ,.a* Is *;ซ VigjOj? M^j;; - = : ;:
- ? i L J ^ysj: # s^Wit .
M : iS *ซ??T; -"::- i : ;
i = = ^ "= L^- * -." =. -..-.t==;ii?- _5^==i_=_ ;
I; ; SB &. ~~. ~r'-ฑ ,-;;-- -,:~J&-~ ".- -J
USEPA1988 ;' , , f f:!."' i^-':!j::^! ; -
I ; j, -, n^ ._.--,_ it ,- ,^ ,, ~. - !
_ ? : ' El " ft=ฃ J ^T 1 .T^ ~75J5=? =" L jfc7!:/"-^: -= | " =" : " =: =
Abdul , Gibson, and ; " rt: : :V ="" : :
Rail990 : * -'--.--- -- - ~_ V - --- .
_
f i S' Vi ^^^^q?1 i: ป;
<: i i - i " r
!! ; ii : i
i, i ; ,
-------
Lab (column)
Lab (column)
Field Pilot Test
Lab (column)
Lab (column)
Lab (column)
Sandy Soil Water
0.5% alcohol ethoxylate
1% alcohol ethoxylate
2% alcohol ethoxylate
Sand Water
Water
A dishwashing liquid
1% Drispac
Ivory dishwashing liquid
Sandy to Silt 0.75% Witconol SN70
Sandy to Silt 0.075% Witconol SN70
Ottawa Sand Sodium sulfosuccinate
Silly Alluvial . Alcodet MC 2000
Soil
14
Wilcodet 100
Wilcodet 100
Tap water
Tap water .
Automatic Transmission Fluid (ATF)
Automatic Transmission Fluid (ATF)
Automatic Transmission Fluid (ATF)
Automatic Transmission Fluid (ATF)
1,1,2 Trichloroethylene (TCE)
1,1,2 Trichloroethylene (TCE)
1,1,2 Trichloroethylene (TCE)
Diesel
Diesel
Diesel
Polychlorinated Biphenyls (PCBs)
Polychlorinated Biphenyls (PCBs)
Oil
Oil
Polychlorinated Biphenyls (PCBs)
Polychlorinated Biphenyls (PCBs)
Polychlorinated Biphenyls (PCBs)
Oil
Oil
Oil
Perchloroethylene (PCE)
Total Petroleum Hydrocarbon (TPH)
49
TPH
PAHs
TPH
PAHs
28
28
28
28
3
25
3
3
3
2
5.7
8.0
5.7
8.0
5.7
8.0
105.0
5.7
8.0
105.0
1.0
2.0
6.0
14
14
14
14
25.5
55
60
72.8
51
52
99.9
100
10
25
10
32
7
19
85
9
15
90
87
96
97
80
0-37
Ang and Abdul 1991
fo-Situ, Inc.,
unpublished report
1994.
Abdul and Ang 1994
Abdul and Ang 1994
Pope and Wade 1995
Bourbonais, Compeau,
and MacClellan 1995
o
Q
-------
i! *!
!! MS,1
i 1 !M II H ซ
I !"! l!|! |
M ! ซ
II' 8ซ=
[jHi
!>
M)N ' ! ! J| jj!1 j N ! 1 j
Ji iliu!
^ -- -- l ^ ป *ซ r ;= : V
s : ^Ni ^ -i- = J- i h I tl^S ^ -:==-*
ii I'll! i ' ':; I"1 ! ' ' ! i Mi
i -= --,- -,- -- - i -
Ji h|i M Mi! i:!i 1 i ! I
ซ f : -3
s ii i ซa
"i N
Table 7.7 cont.
- Summary of Results from Surfactant Experiments
li
Material/
Lab/Field Formation Type- Surfactant Contaminant
" Canadian Forces Clean Sand Water Flushing PCE
1 Base Borden Field 1% NP 100 and PCE
f- Test 1% Rexaphos 25-97
PCE
ป
ซ Corpus Christi, Texas ' Fine-Grained Surfactant Carbon TetracWoride (CTET)
Field Test Sand
v Travis City, Medium Sand Dowfax 8300 PCE and Aviation fuel
-'- Michigan
Field Test
Number of
Pore Volumes % Recovery Reference
6.2 9 Fountain et al. 1995;
10 46 Freeze et al. 1995
14.4 52
3.0 Effluent Fountain et al. 1995;
CTET Freeze et al. 1995
concentration
dropped from
> 1,000 ppm
to < 10 ppm.
NA Mass Knoxetal. 1995
extracted
increase
seven-fold
over water
alone
-------
Chapter 7
Figure 7.6
Results of Diesel Fuel Recovery Experiments Using
Surfactant Water, and Drispac Solution
100
90
80
70
60
50
40
30
20
10
0*
5678
Pore Volume Injected
10
11
12
100% Surfactant (a dishwashing liquid)
A Water
Drispac
The composition of the injected solutions can be controlled to favor the
mobilization or stabilization of a contaminant. Injectiion of oxidizing solu-
tions tends to mobilize contaminants. Injection of reducing agents tends to
precipitate contaminants. However, it is important to ensure that all of the
soil's components will be treated by the injected chemicals, while also not-
ing that the final groundwater composition will be influenced by the final
composition of the treated soil.
Under mildly oxidizing conditions, uranium can be: converted from its
insoluble state to a form that can be transported in water. If uranium in
solution contacts a reducing zone in a soil, then the uranium can be reduced
to an insoluble form. To accelerate the flushing of uranium from a soil,
oxidants and complexing agents (such as carbonate or sulfate) can be added
-------
iiiiri,'1' i,"1"!ป , ,1.'"
ill!" i*1
EH ;:
!' iji"
"ill F!
1 lull,,!'" IIIIIIIIO', "H'l ill!, "
"'I': j IIBIiirii" i,'!,,,!,!,,',:
' tijtil'i
.: (i .'.
Design Development
' l"'l","',fl!!|!'l!i!!:ii!:ii'1!" 'I!
""Jill, It I iiie 1,1 , iililn!'
"1!!"" ....... 8; .....
.'"- ill!'";
; ..... M'S
'";"' ..... ''ill/Il
ซ.,3MH
MWttRHI '"Illiil
i',:':':iii;i '!' /'lill'iiillllllll1 II1'" ''ill,"I"IB "i 'ป'i>I,
I'ii'illUlj!'
!!PI'll'ป< 'llllllillilllR'i 'f1 ,1,'
'^llit'W
"i1:,,,,, iiiii,"1*!, HI,, uii;;,. ' "'
',1 iiiLijiini iiiซ ir j i !,;
fiili
"illilil i; .
Ui'iliiiiin" i "'" :
IlE'iJ'l !"' "Viiv
to the injected solutions. In most cases, a stronger oxidizing solution speeds
the dissolution of uranium and helps keep uranium in solution by oxidizing
zones in the soil where hydrocarbon or other reduced minerals are present.
Once the uranium and oxidizing solution have been removed from the soil, it
may take additional time for the groundwater composition to stabilize.
Sometimes trace minerals, such as selenium, arsenic, and molybdenum, may
become soluble during uranium flushing.
i,1"' ; '""... :
fesituationswhe^acpntanunant^
tion in an aquifer which was previously in a reduced state, a reductant, such as
hydrogen sulfide,can toe added to the flushing solutions being injected into the
contaminated part of the aquifer. The reductant will reverse the effects of oxi-
dation anil will cause many inorganic components in the soil and the water to
become insoluble. If the ambient condition of the aquifer is reducing, then the
j!"1!!111!1:,!'1;!,, I'lii'i'!1,, ';; i|; Jiujiป' : 's,'"!:!,,'" IP; ' ; i-iiittiimi1 liiHiiiipiip'11. . J . j "ซ ป i1 !' '"""Y v'1" .'3'5
inorganic components precipitated during the flushing with a reductant will
remain Msoluble arid immobile. However, if a reductant is used to flush a soil,
but the treated area does not remain in a reducing state, then as the oxidation of
.1(r.y jp, jRBiiv"-a i I 'Si"'!1 '.; !' i "lii tft.yw KatiB-iii- iiijisri^vi i ^p.^ nS a- ซ ป *. ,1 ., , -i,,
the area resumes, more contaminants will again be mobilized.
When using Injected solutions to alter chemical conditions in situ, it is
< 11,1 I; p, , , ""I, |, C* J i, , ||
important to remember that the composition of the injected solutions change
as they move between wells Figure 7.7 shows the results of injecting a
reducing solution in a wellfield for the purpose of reducing selenium to an
iris,piu|le form. The injected solution began with a pH of 6.1 and an oxida-
tion potential of approximately -0.35. However, by the time the injected
solution reached the recovery wells, the pumped solutions ranged from a pH
of over8 with an oxidation 'potent 51of afcoui'^-0.35 to a pH of over 9 with an
oxidation potential of nearly -0.1. Somewhere between the injection wells
and the recovery wells, the chemical conditions as measured by oxidation
potential and pH supported several different chemical Forms of iron, sele-
nium, and sulfur. When using in situ treatment with wellfield pumping,
acceptable" results W'pos^ib'^only'wit^ good" site" "characterization 'and" tech-
nical planning (Merritt 1971; Laman 1989).
Chemicals which enhance die'fiu'slung' of'contaminants'from soils can
mobilize other soil constituents and increase the dissolved solid content in
the groundwater. Whether or not these additional mobilized constituents
pose a problem for the surface treatment process depends upon the surface
process and treated water discharge requirements at each site. In general, the
usepf oxidahts or additives which enhance ttiempbility of contaminants will
7.26
i
-------
Chapter 7
Figure 7.7
Oxidation Potential and pH of Injected Solutions and
Pumped Solutions (Based on Equilibrium Data)
-0.6
increase the total dissolved solid content of the groundwatter more than the
use of reductants. However, under some conditions, reductants can also
increase total dissolved content of groundwater if the reductant reacts to
form a soluble byproduct. For example, hydrogen sulfide might form sulfate
and the sulfate can increase the total dissolved solid conte nt of (lie ground-
water. The design of the surface process needs to anticipate the possible
mobilization of more than just the target contaminant.
-------
lllWlPllil lllll! "."I1' ,J!ll|,iriill!lillll!U^ nHli
iiiiiiiu1 nun la 'iT'II ii, mi,, IHIIIJIK , ' '" in 'i 111 'i, ,i niiiqiHoi! ,' r HIII' !, ir'ปinil
iiiiiii .ill !ซ', i '"ill iii'Ui , ; Bib ',, ' ,,ซ" .iiiii liiiiiiiiii ; ', 3 'i:'"":; - ." < *. i1- :.,.CKI k>,: ,: is,,, .i,;,,, i. *-<ซ;, ,' >,: iป;ซ >,< >'," 4:-,i
IR'iBllllr X 11,1,1!, iillllH^ ' El ,,-lj
Design Development
Uranium in situ solution mining provides a good example of the applica-
tion of innovative soil flushing to remove inorganic contaminants. It in-
cludes: (1) isolating a portion of the groundwater system from the regional
flow, (2) using chemicals to extract minerals from a groundwater system,
and (3) groundwater restoration after mining. Chemicals are injected into a
wellfield that hydrologicaUy confines the movement of the chemical solu-
tions to ''the nSnedzone1: fhe wellfield is surrounded by a ring of carefully
spaced monitoring wells and sometimes a second ring of "trend" wells. The
purpose of the monitoring wells and trend wells is to detect any movement
of chemicals outside the mined zone and to ensure separation of the ambient
groundwater from the chermcal s0|utions used to dissolve the uranium con-
tained in the mined zone. During active solution mining, uranium and other
metals, such as arsenic, selenium, or molybdenum, are dissolved in a chemi-
cal solution. After active mining, traces of the chemical solutions, uranium,
and any
and the groundwater in the mine zone is restored to a composition similar to
the premining composition.
"""'Restoration "of gn^wafer after in situ uranium solution mining has been
completed at several sites in the U.S. Figures 7.8 and 7.9 show the decrease
in total dissolved solids as measured by specific conductance, and the de-
crease in uranium concentration at one restored site as an example. Since
the gisplacemerit of water from pore spaces in the mined zone is not uni-
form, it is common to circulate several pore volumes to restore the water
quality hi the mined zone.
The restoration goal was tte'aDceJtabTb' residual concentration of uranium
and total dissolved solids determined by the appropriate regulatory agency.
The cost-effectiveness of a restoration process depends upon the restoration
v targets for each contaminant because, as the contaminant concentration de-
^e^iiss,"ihf cbste~fiira^se; the cost to remove the last kilogram is much
more costly to remove than the first" kilogram'; Another factor is down-
gradient geochemistry of the aquifer. If the aquifer geochemistry is appro-
priate, the groundwater quality will approach its pre-mining water quality by
natural processes. Cost-effective groundwater restoration requires the use of
treatment processes, groundwater management, and a knowledge of natural
processes active in the mined zone and downgradient. Since groundwater
information is limited by the number of wells and is usually sparse, monitor-
ing wells should be used to detect any unexpected movements of contami-
nated groundwater outside the mined zone during active restoration. After
7.2ฃ
-------
Chapter 7
active restoration, monitoring wells should be used to confirm the chemical
stability of the groundwater.
Figure 7.8
Reduction of Total Dissolved Solids at a
Restored In Situ Uranium Solution Mining Site
3,500
3,000
2,500
2,000
1,500
1,000
500
Start Restoration
_Restoration Target.
_ _t
' I I I I ) I I I I I I I I I I I I I | | | |
10 15 20 25
Pore Volume Produced
30
Specific conductance 10 pore volumes to restoration
Occasionally, chemical solutions used in mining are detected in a moni-
toring well. This is called an excursion. Horizontal excursions are corrected
by reversing the hydraulic gradient to favor flow toward the wellfield and
away from the monitoring well by adjusting the volume of water pumped
-------
.. - - ;.:. Figure 7.9
Uranlum-ConfEimlnated Aquifer Restoration
at an In Situ Uranium Solution Mining Site
.'!'.: ;: Fi.
10 15 20 25
Pore Volume Produced
II 1111 II I I I I I ' '':ซ' II I P
II III I 111 11 I . .J
10 pore volumes to restoration
,ป hllilllill "II I' ill "I '
,,:
,ป.
"- "/! " . i;, 'a,'"'"i1 :i!:,,.., P-I! Mi",!.',: "i11:!"!:!1" i1,i";1:1 ii:,i,;i|i:,!:i ;. " ""|1 i'j;,,1!11: ": v, 'MI, jiiiii: H : i; ir;;11;1]*-' v-"
and injected Use of hydraulic gradients and" flow nets to control solution
movements is an element of solutibn mining technology and can be used for
improved recovery of contaminant plumes.
Figure 7.10 illustrates the in situ uranium mining process. The technol-
ogy has evolved over many years and can easily be applied to groundwater
cleanup and soil flushing. The chemistry of the chemical solutions used in
active mining is normally an oxidant, such as oxygen gas or hydrogen perox-
ide, and sodium carbonate-bicarbonate (baking soda) and is designed to
work with the ambient groundwater to create Eh and pH ranges in the min-
ing solutions favorable to the oxidation arid mobilization of uranium.
7.30
-------
Chapter 7
Figure 7.10
The In Situ Mining Process
Production
(Recovery)
Wellfield Boundary | Wells
_ _, I / Injection Wells
RecoveryPlant \ _InjectionWells
Pump
Different chemicals designed to stabilize or extract contaminants can be
used for different objectives. Other chemistries have been used by the ura-
nium mining industry. The best chemistry for each site depends upon site-
specific considerations. Figure 7.11 shows a simplified in situ uranium solu-
tion mine flow chart. The best chemistry for a soil flushing project is also
dependent upon the site-specific conditions.
-------
"i;,!;
ill!
,i '"'ill
'ill .,;j
'> r <:;"
IE! , I;';1'
Ills
I ! 'f! , ,,.'' iJI?
VIJIIIF11 < i -It I.
Figure7.li """ ' "
Simplified In Situ Uranium Solution Mine Flow Sheet
r "> ['"HJo'jor")
i Acid i Ammonia I
,'",'!! Mr ,: n'',!1'] "i "iiiM" ,, !'!"' ' f 11'A',, i,,,".'if i,,i,", ..nil'1:;,,,,; r> ~v
! -" " ' ' "" '- I I
Dried
Product
i , ' ' ,'' ,' ' ', nil,'' ,f ''','"' !",llli,l!, ,1'. I' '..,:,' , II'" II ' ' ,,ป "HI I "'I' '' I" I' '.I,'1,111 II '"Ii 1111111 J" lijll; Ii,
- , ;i ::~ . i I |( , :f __ ,; , , ,,i[(|| j :. |,-ii|,
The surface equipment used for uranium in situ solution mining is de-
signed to remove small concenSations of uranium from water and recycle
about 95% or more of the water to the wellfield. Ion-exchange processes,
similar to those used in the water softening industry, remove the uranium
from solution and concentrate the uranium in a much smaller water volume.
The uranium is removed from the concentrated solutions by chemical pre-
cipitation and the uranium precipitate is dewatered and drummed. Various
types of ion-exchange equipment are used including up-flow, down-flow,
moving-bed, and fixed-bed devices. Figure 7.12 shows a four-column, skid-
mbuSed, fixed-bed^ down-flow ion-exchange plant and associated equip-
ment. Fixed-bed, down-flow ion-exchange columns are for processing clear
solutions, like those that come from a gravel:packed well. For a soil flush
application, resin-in-pulp is a better design. In the resin-in-pulp design, the
pulp is a mixture of the contaminated soil and the chemical water. The resin
is added to the pulp and the uranium from the contaminated soil is loaded
ii II I
7.32
-------
Chapter 7
onto the resin. The advantage of resin-in-pulp is that the uranium-bearing
resin can be screened from the pulp more easily than the soil can be dewa-
tered or filtered. The capacity of uranium in situ leach plants is a function of
the diameter of the ion-exchange vessels, the number of vessels, and the
amount of product.
Figure 7.12
Ion-Exchange Plant and Associated Equipment
7.4.5 Soil Flushing in the Vadose Zone
The vadose, or unsaturated, zone is the region above the water table in
which the pore space is partially filled with air and water. Contaminants
-------
111 I I 11
Design Development
contaminated sites have some portion of their contamination in the unsatur-
ated zone. In order to quantitatively assess the behavior of contaminate
transport in the unsaturated zone and optimize the design of a vadose zone
recovery system, it is necessary to obtain representative soil-moisture char-
acteristic curves for each specific soil, such as (a) soil suction and saturation
and (b) hydraulic conductivity and saturation.
The concept underlying soil flushing in the vadose zone is the injection of
water-leach solutions or surfactants through horizontal or vertical wells that
are installed above the contaminated zone. The injected fluids mobilize and
move the contaminants to the groundwater table. The contaminants can then
be recovered by pumping. A hypothetical example is shown in Figure 7.13.
;; .. i i1 '/""'y1 ";: aWSL ; :n,,i, 'li'ij'!1!1!! v'; * w* ^-ii'ii hi1'-1 '! *:li!L!:l!;;!: nl ' ii""!:!"""l||li;l!:!l11'1 iv!!' ,, !!/: "''''; !li/'l||T I'*!*'1 \slllil!!f1;;!: V I'l'1!
Figure 7.13
Recovery of Contaminants by Pumping In the Saturated Zone
-:if "> liiiiiiiir r s
O Monitor Well
Vadose Zone Flushing Injection Well
7.34
-------
Chapter 7
Under steady percolation conditions, the injected fluid tends to spread
with depth. Significant spreading generally occurs in finer sand/silt forma-
tions and at low saturations. The vadose flow proportion of the subsurface
environment must be understood when designing injection well patterns.
Figure 7.14 shows an injection well design with flow injected into two hori-
zontal wells. Figures 7.15 and 7.16 show effective saturation profiles in silt
loam, resulting from injection of 30 L/min (8 gal/min) per minute from two
horizontal wells. The figures demonstrate that shorter well spacings of 10 m
(30 ft), as shown in Figure 7.15, provide better coverage (McKee and
Whitman 1991).
Figure 7.14
Injection Well Design with Two Horizontal Wells
xl
Calculated Cross-Section
Horizontal Wells
-------
iiiit ...... IJITM.'F ,, Tra ........ p"u ..... "in ", ............. '; , ' ' 11 ....... ,: ..... i, 'yimi, i,,?!'11',, i, ,, urii
i,;11 win ,/:9^m ......... :ป"
Tl; '!! i ill
'i: >iii
1 :"!"
,"" :,:i|i!HIUI>'lH'" I,;1"'!!!!!!!
Figure 7.1^
Saturation in Silt Loam Using Two Horizontal Injection
Wells with Well Spacing at 10 m (30 ft)
o
50m
100 m
(300ft)
20 0
I
(60ft) (120 ft)
Distance
(180ft)
Spacing: 10m (30 ft)
Length: 100m (300 ft)
Length:
Flow: 3 mn gamn
Effective saturations are values shown In central field of the chart.
i, ; ....... ' i t'li,'!:; " ' : ,
i; ' i'ป"!li!i:i''".,i .. :' I,
7.36
-------
Chapter 7
Figure 7.16
Saturation in Silt Loam Using Two Horizontal Injection
Wells with Well Spacing at 20 m (60 ft)
50m
(ISO ft)
100m
(300 ft) ~
2
_L
80
80
0
20m
(60ft)
40m
(120ft)
60m
(180ft)
Distance
Spacing: 20m (60 ft)
Length: 100m (300 ft)
Flow: 30 L/mln (8 gal/min) ... _i
Effective saturations are values shown In central field of the chart.
-------
fl Ill
lull
illli i,,,! I II '!"|
inii;!11' '! ii: , i" '" ' !j[ i 1',; si,
flf It "i" "V ! , '<,!!, iPS ""'""II!
!F:i', ;' 1 ' ' ,! ," , lซii< ' .',';!;
' Illllli!1 S "'Hill
III II III III
"' Ilk
1 Ill
I ''IN '
\jtswsi\j\j\ i ici 11
7.5 Pretreatment Process
In general, the vadoze zone serves as a conduit for the contaminant to
reach the saturated grounctwater region. The decision to select either hori-
zontal swept or vertical swept depends on the depth-to-water table, the soil
characteristics, and the ratio of horizontal to vertical permeability. Horizon-
I, ', '" , , ',!' ,'M ' , In ,!! 1,11, ' , , ,,'|, , I' , I l|, * J
tal swept, using a set of pumping/injection wells, is generally employed in
the saturated groundwater region (see Sections 7.2 and 7.3). For aquifers
with a shallow water table, horizontal swept is adequate.
As an important step in the pretreatment process, the pump-treat-
reinject system will be operated without adding any chemicals and/or
surfactants in the injection stream. This initial step is to accomplish two
major purposes:
>, ' , ; ' .j,,! ili',,,, i'i|i;,, '"', ir"11"1 i. ป''"il'il i l|l'!ฐ "'ซ'" 'II.n"Hill H '' SiiiJlllill1'",,,!1 A'U* MllP'lllnlli1" ill"*" < : ,i , '":!,!i,!" i,hl!n . !. "!,, Mi11*,11',, "" .U'" ,.li! ,i il ,1 JllHlill",, .1 ,'! .
to check the entire soil flushing system and repair/modify any
. . _ ;..,-<.;; deficiencies; and
to establish hydraulic control and hydraulic communication be-
.' -.- ";.,;;. Jween wejls. , ,
7.6 Posttreatment Process
Since treatment of flushed contaminants is an integral part of the soil flush-
ing process, posttreatment as defined for this series of monographs is not re-
quired. However, after the waste site has been cleaned and all hazardous wastes
have been reduced to acceptable levels, it is necessary to implement a long-term
monitoring program to ensure and verify the effect of remediation.
Legislation governing groundwater monitoring in the United States in-
cludes RCRA, CERCLA and its reauthorization, the Superfund Amendments
and Reauthorization Act (SARA), the Clean Water Act, the Safe Drinking
Water Act, and the Underground Storage Tanks Technical Standards and
Requirements Act. These regulations provide general guidelines and moni-
toring requirements for waste sites. RCRA requires owners and operators to
monitor groundwater quality for at least 30 years after the hazardous site has
been remediated.
I!".' !!%! 'lull I,
7.38
-------
Chapter 7
At a minimum, RCRA requires a four-well monitoring network (one
upgradient well and three downgradient wells) be installed and sampled.
However, since detecting the reappearance of substances at the site is as
important as detecting the migration of hazardous substances off the site, the
monitoring network may include sampling points within and surrounding the
site. The design of the monitoring network is site-specific and depends on
the conditions to be monitored.
For monitoring off-site contaminant migration, RCRA regulations require
a sufficient number of downgradient monitoring wells, spaced according to
the groundwater flow rate of the aquifer, the size of the site, and the value of
dispersivity, be installed to ensure that any off-site migration is detected. An
upgradient well located in each distinct aquifer is necessary to provide a
water quality background reference. To monitor the possible reappearance
of contaminants in the remediated zone, wells used in the soil flushing pro-
cesses during remediation can be used again. These should be supplemented
by new wells to monitor questionable areas in the site.
7.7 Process Instruments and Controls
The process instrumentation and controls necessary for wellfield and soil
flushing control are all commercially available and relatively easy to obtain.
Instruments and controls that should be considered for wellfields include:
submersible pumps;
injection pumps;
filters;
valves;
pipes;
pressure gauges; !
flow meters:
control panels;
tanks;
-------
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safety equipment; and
Bi,i:/',.. I'M ',,i3f,, l
I
water-level and water-quality monitoring instruments.
Instruments and controls that sncniM be considered for water treatment
facilities include:
* columns;
i-1,1; ',:'"'"" pumps;' "
filters;
:'"ป 'Valves; "' ^ ' ' ^ ' ' ' ' '
^ i,, i pipes
''1''.!. :'"'., pressure gauges;" """ ''' " '' ' '
flow meters;
control panels;
tanks; and
safety equipment.
" Hill UPS ill" Illl"' , JlfllH
7.8 Safety Requirements
Safety is an important concern in any operation; soil flushing is no excep-
tion, The safety requirements for soil flushing are common to many site
remediation technologies including soil washing. Accordingly, the reader is
referred to Section 3.8 in this monograph for a detailed description o'f gener-"'
ally applicable safety considerations and requirements.
7.9 Specification Development
Soil flushing requires pumping, water treatment, and reinjection of liquid
through a series of pumping/injection wells. The idea is simple, but the
process if often lengthy. During pumping/injection, aquifers behave like
sponges, giving out water easily, but releasing contaminants reluctantly.
7.40
-------
Chapter 7
Development of specifications for a soil flushing projects requires consid-
eration of the following:
Geology. Contaminants generally enter the groundwater system
in the vadoze zone and gradually reach the saturated groundwater
region. The area of contamination can be estimated by the coring
and sampling program. Two-dimensional and/or three-dimen-
sional geologic cross-sections showing the area of contamination
are useful in calculating the pore volume of a contaminated zone.
Geochemistry. Laboratory tests (Section 7,,4) provide screening
and optimization of the soil flushing process (what chemical at
what concentration should be used). The optimized process
serves as the basis for the design of chemical/surfactant injection
facilities and a water treatment plant.
I
Hydrology. While the soil flushing process controls the contami-
nant plume and reduces contaminant concentration in the forma-
tion, it still may be necessary to circulate many pore volumes of
water before substantial reduction of contamination in the
groundwater is observed, depending on the geochemical param-
eters affecting remediation of the contaminant. Therefore, one of
the most important design parameters is the approximate total
amount of water that must be circulated during the soil flushing
process over the life of the project.
The next step is to estimate flow injection rate and well pumping rate (see
Sections 7.2 and 7.3) for the site aquifer(s). Well flow rates are limited by
the formation's ability to transmit water in the aquifer. The ability is defined
as transmissivity and is determined from aquifer tests. Figure 7.17 shows
radial flow to a well in a confined aquifer.
In addition to transmissivity, the well pumping rate is limited by available
drawdown above the pump in the well, and the well injection rate is limited
by wellhead injection pressure. The hydrologic information is used to de-
sign a wellfield (see Section 7.3).
-------
III! EMJi1 ",!l : K ; ill',1 jr";:
'.''! |i ,;,,i,|fiinni iiiifiiiiiiiiii'i n
tiiCT^
I" .IT
' , ' ir ' , sir i , ' ''i'le
Figure 7.17
Radial Flow to a Well In a Confined Aquifer
Pumping Well
"ill: Jft' " , , ' ' ' , if
7. JO Cost Data
There are many factors that affect the costs of individual soil flushing
projects and, therefore, each site should be evaluated individually. This
section summarizes the range of costs involved in soil flushing programs and
should only be used as a baseline reference. Cost ranges cover a vast degree
of sites and considerations; specific breakdowns are not of use and therefore,
will not be covered here.
. ' , , ' > i . , '.: 1 ." , ' , ,.!'*; IT'. ', '; . 'T1 M!;Ih "! '
The factors generally considered in the cost evaluation are:
licensing,
site characterizatjpn (including drilling of test wells, coring,
'. ; logging),' _ ' ^ ^ ' _ " ^ ' '_ '_ ''"^ "'
baseline water quality conditions,
wellfield design,
7.42
-------
Chapter 7
laboratory testing,
modeling,
well drilling,
well accessories (pump, wire, control par els),
chemicals/surfactants,
water treatment plant, and
long-term monitoring program.
The above list of factors involved in various soil flushing programs is
primarily useful to develop a program cost estimate. However, it does not
include transaction tasks, including legal or technical! personnel. Further, a
contingency should always be included in any estimate to account for un-
foreseen circumstances.
The NRC (1994) has calculated present-worth costs for a pump-and-
treatment system as a function of the percentage of waste removed and these
are shown in Figure 7.18. The cost of operating a pump-and-treat system as
a function of the contaminants' retardation factor (its tendancy to sorb to
solid material in the aquifer) ranges from approximately $2.8 million to
approximately $9.2 million for the year 1994, see Figure 7.19. Together,
Figures 7.18 and 7.19 provide a realistic estimate of soil flushing costs.
7.77 Design Validation
After the process and solution are selected based on laboratory studies, it
is prudent to validate the effectiveness of the process in the field on a
smaller scale and under controlled conditions prior to launching the full
remediation program.
7.11.1 Push-Pull Test
The push-pull test is a simple injection "and pumping sequence of ground-
water spiked with solutes of interest (Drever and McKee 1980). Laboratory
studies are usually conducted under ideal conditions, but can be useful in
determining the relative effectiveness of the process and in planning the field
-------
ifii!
, ''''. ' "/'.. Figure7.18
Present Worth as a Function of Percentage of Contaminant
Removed on Three Discount-Rate Curves
9,000,000
8,000,000 -
2% discount rate
A 3.5% discount rate
5% discount rate
Source: NHC1994
90 ] 99
Contaminant Removed (%)
99.9
99.99
7.44
, i-aiifiiit1 a, ,:;''!!! i 11111111111111 tiiii; jit 'iiiiiiiii i uiiiiiji .i;: j tiiiiiii) ,.,', i, :,. .si MIU , 111,1,1.;.!,iii,aii,:! iiiiiiii,,*': :,; i,,;!;,! juiiins:;, ,i ii1.'i! ai";, , n. a,,' ..iiLi,!!,1];1:!;!:i /, aiBi, m j iiiiiilig^^ .::.i:,.iiii: a.,!;.;1; !.i;,', .i!aii :; ai.!,.1.1.1.11
-------
Chapter 7
Figure 7.19
Range of Costs in Present Worth for the Year 1994 Based on Two
Contaminant Removal Retardation Factors of 99.9% and 90%
56 7
Retardation Factor
99.9% removal
90% removal 8
Retardation Factor The total quantity of a contaminant In a unit volume of aquifer relative to that dissolved In the groundwatar.
Source: NRC 1994
experiment. Laboratory measurements are conducted on small samples and
therefore may not be representative of the site. In addition, hydrogeologic
conditions in the subsurface environment are very complicated and are diffi-
cult, if not impossible, to simulate in the laboratory. Push-pull tests are a
logical step in validating laboratory results in the field.
Figure 7.20 shows a vertical cross-section of a push-pull test arrangement
in the injection mode. Figure 7.21 provides a plan view of push-pull tests in
an isotropic formation (Drever and McKee 1980). The test solution is in-
jected into the formation and is allowed to reside for a few days. Next, a
pump is lowered into the well to recover the solution, and the contaminant
concentration is measured as a function of volume produced. Typically, 10
times the injection volume is recovered. The results are then analyzed to
determine the effectiveness of the process and the retardation effect that can
prolong the cleanup process. >
-------
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lif'Oli1, '".i!J!!l. ' !!! 1 'ill.',"": ""'Hi I"1 ' i' ' A '"II1 "iii,!,^ i1 '" " i .i1"<"^"K^ H'l'.:1"!1* WWII iTii1ป 'IIH'11'!*!
Design Development
Figure 7.20
A Vertical Cross-Section of a Push-Pull Test Scheme in the Injection Mode
Pool or Bladder
Pressure Gauge
Injection Well
The advantage of push-pull technology is that, with the proper design, up
to 100 tonne (110 ton) of in situ soil can be tested, therefore, providing a
larger test than can be noiinally obtained in a laboratory.
7.72 Permitting Requirements
The permitting requirements for using soil flushing processes (or any
other technologies) to remediate a subsurface waste site depend on trie fol-
lowing considerations:
7.46
-------
Chapter 7
Is the contaminant hazardous?
The US EPA will be involved in the permitting process if the
contaminant is classified as hazardous waste.
Is the contaminant radioactive?
The Nuclear Regulatory Commission will be involved in the per-
mitting process if the contaminant is classified as radioactive waste.
Is the waste site located on federal land?
The owner of the federal land in question, e.g., the Bureau of
Land Management, will be involved in the permitting process if
the waste site is located on federal land.
Figure 7.21
Plan View of a Push-Pull Test in an Isotropic Formation
Maximum Extent of Injection Fluid
J_
Injection Well
2 0 24
Distance (m)
-------
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if! ! I ' ' . ' ' ' ,
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Design Development
The state permitting authority will always be involved in any waste
site remediation located in its jurisdiction. Table 7.8 shows the general
guidelines for permitting requirements! Figure 7.22 provides a general
flow chart for permitting requirements. The soil flushing project site
manager should consult with the appropriate permit-granting authorities
for each specific project.
In an effort to avoid dual permitting applications and to streamline per-
mitting processes, US EPA. has authorized some states ("approved state") to
apply their state rules and regulations to the management of hazardous waste
within'the state, in lieu of the; federal regulations?
Table 7.8
General Guidelines In Permitting Requirements
Agencies involved
in permitting
State Agency
US EPA
NRC
Owner of the Federal
Land
Is the contaminant
hazardous?
Yes No
/ /
" . " :
j Conditions
Is the contaminant Is the waste site located
radioactive? on Federal land?
Yes No Yes Mb
-------
Figure 7.22
General Row Chart for Permitting Requirements
9
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1
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-------
if:; t,
system downtime,
operation schedule/milestones, and
J '
> Quality Assurance/Quality Control (QA/QC).
iii ;"' ,::. : '.: ' i 1... ,. '
Hydrodynamic Performance Measures:
> plume control, and
modeling conformance.
k!!llll|'7!|i!i! IV 'I!!,I1!?1: "I I'!!''MI' llrtlWJT"!: 1! |'''l
Water Treatment Performance Measures:
rate of reduction of contaminant concentration
f contaminant removal efficiency, and
II "; ซ'
waste disposal.
Cost Performance Measures:
capital costs, and
in in 1 1 |n(i
operating costs.
1 ' '
i
Safety Performance Measures:
safety records.
7.74 Design Checklist
:. ': :;;" : ' ;;;; ?r " ii "ii : """",::
The following is a design checklist for a soil flushing project.
:L. Geology
Geologic cross-sections
Recharge areas
Discharge areas
Hydrology
Hydraulic conductivities
i) 11 ( i Pi Ii 111
Transmissivity
Storage coefficients
7.50
| '
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-------
Leakage between aquifers
Water levels
'.''I . ,':> .*V:);.ri;: ;
Well survey records
/ ,' , ," ,;'',; r n .," ;
Baseline water quality
jeochemistry
Adsorption characteristics
Biqdegradation characteristics
,I,.'S , .'.: , ' _-- ..... jJM., ',';.:.. ~ - -,. ",t ',:i r,j7
Contaminant
Type of contaminant
Contamination source
Amount of contaminant
lisi,', ',,; - ::M,^^::i:~ *:;- f--;, "fis1 ^..fis:^": i ..,
Size and boundary of contamination
Chapter;
Well location
Well size, depth, screen intervals, and material
Well production rate
Well injection rate, injection pressure
Well completion arid well integrity
Computer Modeling
Model verification
Hydraulic modeling of site
Flushing Solution
Concentration
^
Vater Treatment Plant
..,.. *: ;' ',-;if., j v ...... >',' ,.-. Tjf.;. .-, '..
Throughput
Process7flow diagram
Amount of solid waste generated
-------
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-------
Chapter 8
IMPLEMENTATION AND OPERATION
8. J Implementation
8.1.1 Site Characterization .
Before beginning a soil flushing project, background information about
the site should be reviewed with particular emphasis on the geology, hydrol-
ogy, and nature of contamination. The field implementation program starts
with test-well drilling. Many factors must be evaluated when choosing well
locations, well-completion techniques, and sampling and aquifer testing
programs. These factors generally include:
The material of the well casing will it react with groundwater
or contaminated groundwater?
Cement or other material used in the well completion will
these materials introduce contaminants to the groundwater?
Well completion techniques will they promote inter-flow be-
tween aquifers?
Drilling fluid will it contaminate the groundwater?
Well screen intervals will they be able to isolate the contami-
nated zone?
Well size will it be large enough for setting the pump, bailer,
or other sampling devices?
-------
" II
.,;;/> ''>> !;:/ ' .f, i,' , i, ].,, ,;,: , " r T- :: ' 1, i-i1"! i,,
A study to assess the present contamination should identify the following
parameters:
, " ' ,| "i i " ' "" .'I'1! Jllllll,1 |! ' " ' i| ' . . '' In* " 1 ป 'II1 ,
kind of contaminant,
contamination source, "
I
amount of contamination,
, | : -
. ' ,",- .' ";.ซk' MUSI iii,i,!','1! '"ji" T H. live,-, ';'.'.. ;"' "it-;1"1, ">; -i > 3 ""
size and boundary (three-dimensional) of the contamination, and
environmental impact of the contamination.
(
Figure 8.1 shows the sequence of information acquisition. In addition to the
information on the contaminants of interest, the site-specific geology and
.1 , , III,1 'I I' ;, '" .i'1 I,,! 1,, I'1 i!!'1l,;/J 'jr'!"!;,, l ', II ' L , I, . 7, ,' ,il'"|, 1,1,1111!
hydrology should be defined.
8.1.2 Wellfield Design
1 if;' !" i'i'"" I : Jjiiiiiiii i\ n ! I" J",J|l li"ii i 'n ', (Pijij,1,'IJj !];; ', :' n" | li|,ii . | ป !', ilj ป.,"; , : [ n ,' ;;!i ,,;,,, , ' !' , "' : ' \ '"'3' "l!11!!'1'1!
The wellfield patterns discussed in Section 7.2.2 are used when the con-
taminated area extends in all directions over a large area. Formation geol-
ogy, hydrology, and characteristics of chemicals of concern should be con-
sidered in selecting one of the standard patterns . Because of the anisotropy,
heterogeneity, and spatial variation of formations, computer models are used
to optimize^ the wellfield design. A computer model, called 'Tracer" (de-
veloped by C.R. McKee) was used to study the effectiveness of wellfield
designs for in situ uranium operations. This model illustrates the importance
of wellfield design in effective mineral recovery, and, therefore, the associ-
ated contaminant cleanup (soil flushing) scenarios. The same concept and
principles can be applied to a number of DOE sites and sites with uranium
contamination.
The importance and effect of wellfield design is amplified by three sum-
maries of uranium extraction which are presented on the following pages.
'"" ' '!
8.2
-------
Figure 8.1
Information Acquisition Sequence
Coring,
Logging
Cross
Section
1
-- ---
1
Soil
Sampling and
Analysis
Geochemical
Information
1
Wells
1
1 1
Water
Sampling
and
Analysis
1
1
Water
Quality
Water
Level
Measurements
Hydraulic
Gradient
1 1
1
'.
i
!v
Baseline
*1 Water
Quality
1
Present
Conditions
1
1
Remediation
Program
1
Tests, Slug
Tests
1
Hydrologic
Properties
i
1 "i
Tests
1
Dispersivity
1
9
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1
00
-------
H", SMI > i , ซ==
p :;
IJ -- t
00
js...
30m (100 ft)
IS m (50 ft)
Om(0ft) -
-15m (-50 ft) -
Figure 8.2
Fourteen-Well Production Match, Brunijexas
% \ ^v.
-30m (-100 ft) IJ 3 12.
-40m (-130 ft) -20m (-65 ft)
Om(0ft)
Distance
20m (65 ft) 40m (130 ft)
r Injection
Production
Tracers plotted at 1-day intervals; Total Tfme: 56 days; North is at top of figure
-------
Chapter 8
8.1.2.1 Bruni, Texas
This is one of the oldest in situ uranium mining operations. The wellfield
consisted of seven injection wells and seven recovery wells. The wellfield
was designed based on speculation rather than engineering considerations.
Figure 8.2 shows the fluid migration path and history. A number of hypo-
thetical particles, or tracers, were placed at the circumference of injection
wells and released at the moment when the leach solution was supplied to
the injection wells. The tracers moved along streamlines and were plotted at
one-day intervals. The resulting plot shows the path followed by the leach
solution in a given direction. A high density of paths indicates slow fluid
velocity. It was not a good design. Figure 8.3 is a time plot of actual ura-
nium production and computer match generated by the 'Tracer" computer
program. The relative concentration of uranium products was plotted to
preserve the confidentiality of the project. The actual uranium concentration
produced was low, and the production time was long;. The large amount of
lixiviant (the chemical solution used to mobilize uranium) leakage to the
northwest, west, and southwest side of the wellfield contributed to the poor
recovery of uranium in this wellfield operation.
Figure'8.3
Production Match to Fourteen-Well Pattern, BruniJexas
10 IS 20 25 30 35 40 45 50 55
Assumes that 10 streamline pore volumes are required to leach uranium.
-------
Implementation ana operation
iiii i, ! in i
'"' ,1 ,, i r I
I,
8.1.2.2 Irrigary,Wyoming
The isolated five-spot pattern (four injection wells and one production
well) is a very popular design for in situ uranium pilot operations, especially
in formations where well injection capability is limited. A computer model
projected the flow paths that the lixiviant followed as it moved through the
aquifer (see Figure 8.4). Figure 8.5 shows the computer match of the pro-
duction curve.
(' ..... PHI ' . : 'i ' 1 1
Figure 8.4
Five-Spot Production Match , Irrigary, Wyoming
80m (260 ft)
60m (200 ft)
40m (130 ft)
20 m (.65 ft)
Om(0ft)
Om(0ft) 20m(65ft) 40m(130ft) 60m(200ft)
Distanc
80m (260 ft)
stance
'! ";' I
-* Injection
Tracers plotted'^ 1-day Intervals; Total Time: 100 days; North Is at top of figure.
8.6
-------
Chapter 8
Figure 8.5
Production Match to Five-Spot Well Pattern, Irrigary, Wyoming
10
20
30
40 50 60
Time (days)
70
80
90
100
Assumes that 8 streamline pore volumes are required to leach uranium.
8.1.2.3 Zamzow, Texas
This project employed an uncommon design dictated by the unusual con-
figuration of the project's physical layout the high-grade uranium was
deposited in a long and narrow strip (See Figure 8.6). Under these condi-
tions, conventional wellfield design would not work very well. The wellfield
was designed to accommodate the deposit with the help of a computer
model. The production curve reflected the effectiveness of the operation
high uranium concentration and short operation duration (see Figure 8.7).
-------
p--
Figure 8.6
Eleven-Well Production Mcrtch.ZamzowJexos
CO
00
80m (260 ft)
60m (200 ft)
40m(130ft)
20m (65 ft)
Om (Oft)
J_
i
Om(0ft) 20m(6Sft) 40m(130ft) 60m(200ft) 80m(260ft) 100m(320ft) 120m(400ft)
Distance
> Injection
tecorapifflat 0.1-day fntenrafisTotal Time: ISd^sjNortliisattopoffigure.
-------
Chapter 8
Figure 8.7
Production Match to Eleven-Well Pattern, Zamzow,Texas
.678
Time (days)
14
Assumes that 6 streamline pore volumes are required to leach uranium.
8.2 Start-up Procedures
8.2.1 Baseline Wafer Quality
To define the degree of contamination, the baseline water quality in the
formation of concern must be established. Baseline information is obtained
by determining water quality in the affected aquifer either:
prior to suspected contamination events; or
outside of the contaminated region once contamination has
occurred. ;
The information is most useful if it has been collected over an extended
period of time during different seasons of the year. This enables the
user to properly assess monitoring data in light of temporal fluctuations
in water quality. |
-------
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impiemeniunui i ui iu
ti'iii.^.! i,."1 :ii,!.. '
till [ilkik "i: ' I
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lit
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lliii' ;iซ
It is important that all information in the baseline study be obtained
through proper procedures for the sampling, handling, storage, and analysis
of aquifer waters. The sampling program should continue throughout the
remediation program.
8.2.2 Equipment Shakedown and Calibration
To minimize unforeseen problems, ati equipment must be calibrated and
subjected to performance shakedown before the start of the remediation.
Power supplies, flow lines; valves, gauges, meters, lighting, data loggers,
computers, sampling devices, and other equipment should be tested.
i
8.3 Operations Practices
8.3.1 Pilot Tests
Pilot tests usually involve a small number of injection wells and recovery
wells. The most popular wellfield patterns are single two-spot, single three-
spot, or single five-spot patterns (see Section 7.3). A small-scale water treat-
ment plant, usually with a flow rate of less than 400 L/min (100 gal/min), is
part of the pilot test.
Selected coring/soil samples in the test area are pilot tested to validate the
remediation process. The pilot test will evaluate:
.. the effectiveness of the process to remove the contaminant from
the subsurface environment;
the ability of the water treatment plant to recover contaminant
from the pumped solution;
. -the consumption rate of chemicals/surfactants in the soil flushing
process;
the operation of testing equipment; and
the spacing between wells.
8.10
-------
Chapter 8
Once the results of the pilot tests are compiled, the data may be applied to
the complete remediation site. Between the injection wells, recovery wells,
and the cored soil samples, sufficient data will be available to implement the
remediation.
8.3.2 Traverse City, Michigan Pilof Test
A surfactant pilot field test was conducted at the U.S. Coast Guard facility
in Traverse City, Michigan, during June 1995. The contaminants had under-
gone a decade of bioremediation, with moderate levels of tetrachloroethyl-
ene (PCE) and aviation fuel contamination remaining, specifically, up to
1,000 ng/kg (ppb) and 1,000 mg/kg (ppm), respectively. PCE concentrations
less than 10 ng/kg (ppb) were common in the groundwater. The surfactant
test occurred in a highly permeable sand formation, with natural groundwa-
ter velocities of 0.91 to 1.52 m/day (3 to 5 ft/day) and iminor drawdowns
realized at pumping rates exceeding 56 L/min (15 gal/min).
The primary objectives of the test were to maximize surfactant recovery
and evaluate the vertical circulation well (VCW) system. A secondary ob-
jective was to enhance contaminant removal; this was a secondary objective
because prior remediation activities had minimized contaminant concentra-
tions. Laboratory, batch, and column studies were conducted to evaluate the
interactions of surfactant, contaminant, media, and groundwater. Modeling
studies were used to design the field-scale implementation of the VCW sys-
tem. Preliminary tracer studies were conducted to verify the proper installa-
tion of the VCW and characterize system hydraulics. The design was based
on 95% recovery of the surfactant, with the actual recovery exceeding this
value. The hydraulics of the VCW system were less than optimal in this
highly conductive formation because an extraction rate of 10 to 15 times the
injection rate was necessary to achieve >95% surfactant: recovery.
The surfactant (Dowfax 8390) was injected at 10 times the critical micelle
concentration to promote solubilization. A total of 2,043 L (540 gal) of
(3.8% by weight) Dowfax 8390 was injected during the course of the study.
Surfactant-enhanced solubilization increased the mass of contaminant ex-
tracted by a factor of five to seven versus water alone for PCE and methy-
lated alkanes; 'this was especially encouraging, given the relatively low levels
of contaminant present (Knox et al. 1995).
-------
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impiemenTanon unu
8.4 Operations Monitoring
I, Ill'' ", " i,1 ',ii ' 'I II1, i , , ,i I,, i J ' III: ' ' ,' " ' ' '. iiป ,;in, is '
, . - I1',-"'1' ' ' ul, . " .; ' ,. , : j; : : , '''.! ''i- ป'
8.4.1 Scope "^ ; ^ __" ^ ^ ^ ' ^/;"
Environmental monitoring is typically the subject of negotiations
between responsible parties and agencies, based on statutes and regula-
tions. There are two basic approaches to examining and selecting what
to monitor. These are:
V monitoring for all substances relevant to the waste type; or
. applying key indicators that give early warning of leakage.
For example^ Plumb (1991) studied 500 contaminated sites and concluded
that VOCs are the most significant contaminants in groundwater associated
with disposal sites. Rather than conduct^ complete water-quality analysis
for all organic contaminants, which can cost up to thousands of dollars,
Plumb suggested that analyzing samples for only VOCs alone can success-
fully provide an earry-waMng of excursions that then justify more extensive
laboratory analysis. The key indicators for VOCs are listed in Table 8.1.
Such an approach can save both time and money.
Some other key indicators advocated for detecting water-quality problems
associated with particular contaminants are":
'Mil, .: j. i,,1!1 ,..'.'. - . . !! 'i,, "!!; fcilV fill'1"-;"! II ,!| - '''' ":"'1' ' ; '" '" I1"1""1 ' -
total organic halogen (TOX) for pesticides;
total organic carbon (TOC) for general organic substances; and
flame ionization detection (FID) or photo ionization detection
(PID) responses of soil vapor for volatile organic components
(Murphy 1991).
8.12
-------
Chapter 8
Table 8.1
Key Indicators for Volatile Organic Compounds
VOC
Methylene Chloride
Trichloroethene
Tetrachloroethylene
Trans-l,2-Dichloroethene
Chloroform
1,1-Dichloroethane
1,1-Trichloroethane
1,1,1-Trichloroethane
Toluene
1,2-Dichloroethene
H (V ppm/W ppm)
292
88.8
161.8
57.4 i
33.9
592
252.9
206 !
69.0
11.9
where: Cv = VOC concentration (mg/L) In vapor above water level; and
Cw = VOC concentration In water.
8.4.2 Procedures j
Environmental site monitoring usually requires taking samples by pump-
ing water from wells and analyzing them in a laboratory. The time between
sampling and receipt of the analysis results can be weeks. It is difficult to
make a real time decision regarding an excursion from a site. In addition,
most of the samples taken at sites throughout the United States do not show
any contamination. Monitoring is expensive; it includes sampling equip-
ment, containers, labor, transportation, and a per-parameter charge for each
test the laboratory conducts. Therefore, if this monitoring cannot provide
timely data for operations, it wastes limited resources.
This situation has generated substantial interest in rapid, real-time, cost-
effective field analysis and in situ monitoring methods. Field screening of
soils and water samples for appropriate indicator parameters can be used to
indicate the presence of contamination. Such methods offer the promise of
better decisions as to whether or not to collect a sample, where to collect a
sample for laboratory analysis, and how to define the boundaries of contami-
nation. Two key objectives in developing field screening and remote
-------
' -it"
f '
< I
";" I/! :' Y'M'YJh i: ":<', '
Implementation ana Operation
, . , ,.. , . , , , . ,,
environmental analysis technologies are identifying a substance of interest
and providing necessary quantitative information about the substance Within
the site. Field determination of what to do with the sampling and monitoring
program is called field screening.
Advanced comm^d-and-coritrpl systems that use sophisticated communica-
tions technology will be used extensively in the future (see Figure 8.8). These
systems can also include computer programs" providing for automatic notifica-
tion of regulatory agencies and key site personnel, or trigger alarms to address
various situations that may arise (McKee, Schabron, and Way 1995).
In addition to the ring of monitoring wells depicted in Figure 8.8, the in
situ uranium mining industry uses an inner ring of trend wells for early de-
tection. In the event of contaminant migration, the inner ring monitoring
provides advance warning enabling corrective action before contamination
migrates beyond the outermost boundary.
' ป '; , ; ;' ' iini ;ซ' ,;ซ , ' || '" ^ ^ : "t ,
' i1'" f " '' " '' : " ' ' "
I in
-
8.5 Quality Assurance/Quality Control
A QA/QC program is essential when soil flushing is used. The program
should address several major areas, including the following considerations:
Responsibility. Quality assurance involves the entire organiza-
tion, from top management to the individuals participating in
every phase of work.
'i, | " ' ''' f ,, i , ii|i! pimii "]' 111,111 ||j|| "I], s , i jfi1 II ', 'M 'iii,'1!;,' ' !'" ,' 'i1""'1' ' ,' I!"1' ""' !""'' !''iliii'li""!'1 r "i"1"1'"''1' !
ป Training and Certification. Proper training and certification of
individuals will ensure that soil flushing data is collected and
interpreted correctly.
Documentation. Standards and procedures for collecting and
interpreting data must be developed and documented.
Instrument Calibration. Establishing instrument calibration stan-
dards and procedures is important, especially for comparing data
collected at different times, under different environments, and
with different instruments.
;'' Y . .. "" "SSY,- '> ,J'. 'fill';! :Y""i I;!!.1, f ,' .1* ,;H" !,..!<<' ' "1 :'[, ,IM"l,,!l
Table 8.2 identifies several specific items that should be included in a soil
flushing QA/QC program.
8.14
-------
Chapter 8
Figure 8.8
Multi-Aquifer Monitoring
Satellite
On-Site Data x
Storage x
Information
Center
Worker Plotting
Well Monitoring
Information
Monitoring wells at the remediated waste site are in communication with personnel responsible for the site via
communication links.
-------
' f'"1
ill! Ill*
! " " ' i""|!'l'l"'! i in!111 ' i i 1 i ,": I- i !! t ' ""!.,',!:
Table 8.2
Features of a QA/QC Program for a Soil Flushing Project
Item
QA/QC Program
Hydrologic measurements
Sample collection
Sample preservation
' , l,|l' ," 1 ' ป ' ' !' '':
Sample storage/transport
Verification of sampling methods and
analytical procedures
Chemical/surfactant/contaminant
concentrations
Measure to certain accuracies
!l
Ensure representative samples, not biased samples
Preserve samples in the field as soon as possible after
collection
flCii,,, '' S! 'V "1 ill , :'!',, ' i ;].,),, ;' , ' , , J;!,,!, lir H",
Minimize the chemical alteration of samples prior to
analysis/chain of custody
Use field blanks/standards/duplicate samples
Measure to certain accuracies/mass balance
I.;,,,!]',I , l|l| 'I ,|' '
8.16
-------
Chapter 9
CASE HISTORIES
This chapter presents seven soil flushing cases.
A ground water clean-up project conducted in the United Chrome
Products site in Corvallis, Oregon. Chromium was recovered
from a contaminated aquifer using a network of extraction/pump-
ing wells, two infiltration basins and one infiltration trench.
A pilot study using surfactant to recovery polychlorinated biphe-
nyls (PCBs) and oils from contaminated soil.
A laboratory column study conducted to investigate the potential
of using soil flushing for the remediation of sandy loam contami-
nated with either lead, lead sulfate, lead carbonate or lead and
naphthalene.
A field pilot test at the Borden Canadian Forces Base near Alliston,
Canada. Surfactant-enhanced, pump-and-treat remediation of aqui-
fers contaminated with tetrachloroethylene (PCE), a dense-non-
aqueous-phase liquid (DNAPL) was evaluated.
A remediation project at the Fairchild Semiconductor Corpora-
tion in San Jose, California. Pump-and-treat soil flushing was
employed to recover organic contaminants (xylene, acetone and
1,1,1-trichloroethane).
The current groundwater clean-up program at the Savannah River
Hazardous Waste Management Facility. Enhanced recovery tech-
niques were used to remove were 1,1,2-trichloroethylene (TCE),
tetrachloroethylene (PCE) and 1,1,-trichloroethane (TCA).
A remediation project at an IBM facility in Dayton, Ohio.
Pump^and-treat technologies were used to remove 1,1,1-
trichloroethane (TCA) and tetrachloroethylene (PCE) from
the aquifer.
-------
Case 1 Gro^nd^terjRemedfation at
the United Chrome Superfund Site
The United Chrome Products Site is a former industrial hard-chrome
electroplating shop located in Corvallis, Oregon. Leaking plating tanks and
the discharge of rinse water into a disposal pit during the shop's operation
between 1956 and 1985 caused the contamination of soil and groundwater
underlying the facility. Soil contamination greater than 60,000 nag/kg chro-
mium, and groundwater contamination exceeding 19,666 mg/L chromium
were measured adjacent to the plating tanks^ The US' EPA placed thesiteon
the National Priorities List in 1984. in i9งf>, US EPA began remediation
activities that have continued to the present time. These include the con-
struction of twp infiltration basinsto flush contaminated spils, a 23-well
groundwater extraction network hi low permeability soils, an injection and
groundwater extraction network in a deep gravel aquifer, and on-site treat-
ment of concentrated chromium wastewaters (McPhillips et al. 1991). Table
9.1 shows the subsurface and contamination conditions at the site.
Table 9.1
United Chrome Site Subsurface and Contaminant Conditions
Geologic Unit
Description
Contamination
Cleanup Goal
Upper zone
Upper aquitard
Deep aquifer
Lower aquifer
5.5 m (18 ft) of coarse to
fine silt.
0.6 to 3 m (2 to 10 ft)
thick of stiff, dark, grey
clay.
4.6 to 7.6 m (15 to 25 ft)
thick of inlerbedded silty
sand and sandy gravel
layers.
At least 12 m (40 ft) of
plastic clay.
High concentration of chromium
(III) in soil, low solubility in
groundwater.
High concentration of chromium
(VI) in soil and in groundwater
(as high as 19,000 mg/L).
1
High concentration of chromium
(HI) in aquitard soil.
Chromium (VI) was detected as
high as 8 mg/L in groundwater.
10 mg/L chromium
0.05 mg/L chromium
9.2
-------
Chapter 9
Beginning in December 1987, the US EPA implemented a two-stage
remediation plan. The first stage was directed toward cleanup of the facili-
ties, surface water, soils, and the upper-zone groundwater with the objective
of protecting the deep aquifer from further contamination. The first-stage
groundwater cleanup included:
Decontamination (high-pressure spray wash) and demolition of
the United Chrome building.
Excavation and offsite disposal of about 1,000 tonne (1,102 ton)
of heavily contaminated soil (from the disposal pit and plating
tank areas) and contaminated disposal debris.
Installation of 23 groundwater extraction wells and 12 monitor-
ing wells in the upper zone.
Construction of two infiltration basins over the disposal pit and
plating tank areas with infiltration rates averaging 28,760 L/day
(7,600 gal/day) in Basin No. 1 and 11,350 L/day (3,000 gaVday)
in Basin No. 2 during dry summer months. During the winter
months, infiltration rates decreased by 50% or more compared to
the summer months.
Construction of an infiltration trench down the axis of the
upper-zone plume with infiltration rates averaging 9,460 L/
day (2,500 gal/day).
Construction of a water treatment facility, including the installa-
tion of a chemical reduction and precipitation and clarification
treatment system for chromium removal,
Rerouting of the local drainage ditch to bypass the site.
Table 9.2 provides a summary of performance data for August 1988
through December 1990 (Stage 1).
-------
si.
11 ,| l)|
fable 9.2
Summary of Performance Data
' "' ! " '
1
UNITED CHROME PRODUCTS SUPERFUND SITE
Extraction and Treatment System Summary
August 1988 through December 1990
i l;1' "'-Parameter
Groundwater Extracted
Influent Cr(VI) Concentration Range
Mass of Cr(VI) Removed
Infiltration Recharge
Average Effluent Cr(VI) Concentration
Sludge Produced (25% solids)
Total
25,3oX>;otiO L &700.000 gal)
' " ' ' | " '"
1,923 mg/L to 146 mg/L
-.-- :: " : ', ,),::, ",
11.045 kg (24,300 lb)
17,800,000 L (4,700,000 gal)
172m' (6,070ft3)
l
Average Daily
43,100 L (11,400 gal)
18.7 kg (41 lb)
30,000 L (8,000 gal)
1.7 mg/L (monthly)
0.28m3(10ft3)
, ii'l! i." I'm. .IP"
Figure 9.1 provides curves of concentration versus pore volume extraction
fqr three different areas at the site. The two curves shown for Wells E'Vy-ll
and EW-28 (both wells in the upper zone) represent actual field conditions,
whereas the third curve was generated in a laboratory column leaching test
using contaminated solid collected ori-site with a core sampler. The curves
are generally similar in shape.
It was concluded that, "Infiltration basins have been found to be effective
for delivering large amounts of flushing and recharge water to near-surface
contaminated soils, whereas infiltration trenches may be more effective for
delivering recharge water to deeper contaminated soils. Either structure can
result in accelerated soil and groundwater cleanup in the areas around them"
(McPhillips et al. 1991).
, : ,': , '. : I \
The second stage of the remedial action was directed at cleaning the deep
aquifer. This work resulted in the installation of seven deep aquifer extrac-
tion wells and two irrigation wells.
9.4
-------
Figure 9.1
Concentration vs. Pore Volume Extraction Curves
10,000
1,000
Upper Zone Cleanup Goal
Laboratory Column Leach lest Results
I I I I I
10 11 12 13 14 15 16 17 18 19 20
0.1
0 1
O
Q
-------
Cose 2 In Situ Surfactant Flushing of
PCBs and Oils Pilot Test
A field test of the surfactant flushing method at a site contaminated
with polychlorinated biphenyfs (PCBs") arid oils was performed by Abdul
etal. in 1992.
The site was used to store unused machinery. Widespread soil contamina-
tion with PCBs and oils was confined to the fill material and w_as thought to
be the result of leaking machinery and from contaminated fill. To contain
the contaminants within the fill zone, a containment wall made of a mixture
of clay and cement was installed around the site.
- " I ' !
A test plot, 3.05 m (10 ft) in diameter by 1.52 m (5 ft) deep, was selected
in an area of high levels of contamination. The study involved applying a
surfactant solution on the test plot to wash the site material and carry the
leachate down to thedepressed water table, where it was collected by pump-
ing a recovery well installed through the center of the plot. The leachate
pumped to the surface was biologically treated to degrade the oils and sur-
factant, and the PCBs were removed from the leachate by an activated car-
bon system.
The upper 4.0 to 4.6 m (13 to 15 ft) of the 20,000 m2 (5 acre) site con-
tained fill material. The fill material resides over a layer of fine-grained
alluvium, which varies in thickness from a few centimeters to several meters.
Below the alluvium, an extensive layer of sandy glacial outwash extends to a
depth of about 18 m (60 ft), below which is a thick layer of clay. Soil cores
from the test plot indicated concentrations of up to 6,223 mg/kg PCBs and
67,000 mg/kg oils. The test plot initially contained about 15 kg (33.1 lb) of
PCBs and 157 kg (346. lib) of oils.
Figure 9.2 shows an example of a mathematical simulation of surfactant
washing of the test plot.
The surfactant washing program consisted of two phases. Phase 1
consists of a 70-day surfactant flush followed with a 30-day water flush.
Phase 2 consisted of a 90-day surfactant flush and a 24-day water flush
followed with laboratory soil column test. Table 9.3 presents the results
of the program.
9.6
1- ...... JIi ........... fcii ..............
-------
Chapter 9
Figure 9.2
An Example of Mathematical Simulation
of Surfactant Washing of the Test Plot
Aqueous Surfactant Solution
I || II, I I I I I
Reprinted from Abdul et al., "In Situ Surfactant Washing of Polychlorinated Blphenyls and Oils from a Contaminated Site,'
Ground Water. Volume 30, Number 2, March-April 1992, p 223, with permission of Ground Water Publishing Company.
-------
: - -, - - --- -,=-V- -'--: ; :;
Table 9.3
; Surfactant Washing Program
Co - Tjjne Elapsed
'---- - - - Phase I 70 days (July to October, 1989)
, . plus 30 days rising with water
; Phase H 90 days (June to September,
1990) plus 24 days rising with
: water
-, Laboratory soil column test
, ?
Average Average
Surfactant Recovery
Injection Rate Rate
291L/day 594L/day
(77 gal/day) (157 gal/day)
92L/day N\
(24.3 gal/day)
N\ m
Cumulative Total
Contaminant Recovered
PCB Oil
1.6kg 17.0kg
(3 Jib) (37.4 Ib)
4.1kg 59.4kg
(9.0 Ib) (130.7 Ib)
NV N\
Cumulative Number
of Washings
(pore volumes)
5.7
ao
105.0
Cumulative % of
Recovery
PCB Oil
10% 10%
25% 32%
85% 90%
-------
Chapter 9
Figure 9.3 shows mass percent of PCBs and oils remaining in the test plot
after the Phase 1 and Phase 2 flushings. Figure 9.4 provides a plot of the
percent of PCBs and oil remaining in the laboratory column soil as a func-
tion of pore volume flushings.
Figure 9.3
Mass Percent of PCBs and Oils Remaining in the
Test Plot After Phase I and Phase II Washings
3456
Number of Washings (Pore Volumes)
PCS
O Oil .
Reprinted from Abdul and Ana, 'Surfactant Washing of Polychlorlnated Blphenyls and Olid from a Contaminated Field Site:
Phase II Pilot Study,' Groumfwater, Volume 32, Number 5, September-October 1994, p 731, with permission of Ground
Water Publishing Company.
It was concluded that, "the in situ surfactant washing process is a
viable remediation technology for hydrophobic contaminants" (Abdul
andAng 1994).
-------
II11!:1' IS" IHireil Jfc IN, l:
" isii , ' ' IIIM ">: ' '. '; i 'ป[' ; I IE lit ":?' ,- : si!' ,
-, t , ....... s * ..... if i yip: , iiii ..... , ; " ........... i
L 1 :i,||, ii1,
, , i|
I1: *" 'III",,,, '
ill 1111 l ' 1 Jit 11111: : 11 Hill "' ", :::;
I! :!'lini|i' M i 1 ilHilIHlh,;; nll!|.;<
-III!IB::if .V,! ".V '
ill,: MFi
Figure 9.4
Laboratory Column Study of Surfactant Washing of RGB-Contaminated Soil
10 20 30 40 56 60 70 80 90 100
Pore Volumes
PCS
0011
Reprinted"from Abdul and An^Surtactan't'fes'hln^^
Phase II Pilot Study,' Ground Water, Volume 32, Number 5, September-October 1994, p 731, with permission of Ground
Water Publishing Company.
ili ii, iir mi, r
Iff '
, ' ,l|n, 'I, 'I , 1,1,1 j,1
" ! " : T '( " IE:!! ?
ill? ,,,inii hn I,
Ail1!!!;11 "I,1'1,'"
"' ' ' '. ' """i,;1 i ra.'"..-.lM'.i''? "', HI; I I " I " ' ,! ' ' ' "
,.,: . .. . , : i,1;,,|M, ,":, "in, j,,,*1::,,'..'i,, iiiiii'iii:;1.!.! ..;':.., i.1;!1 ",:ii ii',",,,, v'j",:,:::',,, i: :,, " l| II
Cose 3'column> study of Soil Flushing of
a Lead-Contaminated Sandy Loam
Several column tests were performed by Reed, Carriere, and Moore
(1994) and Reed, Moore, and Cline (1995) to investigate the use of soil
flushing for the remediation of a sandy loam contaminated with either lead
(Pb[n]), lead sulfate (PbSOJs]), lead carbonate (PbSO3[s]), or lead (Pb) and
naphthalene. Lead was chosen as the study metal because of its widespread
existence at Superfund sites. Over 60% of the National Priority List sites
that have signed Records of Decision have heavy metal contamination.
i in
9,10
-------
Chapter?
PbSO4(s)(anglesite) is a common form of lead contamination at hazardous
waste sites, especially at battery crushing and recycling facilities. PbCO3(s) is
expected to form in soils with a high carbonate concentration. Naphthalene was
used to simulate the fate of lead in the presence of a polycyclic aromatic hydro-
carbon (PAH). The following extractants were investigated: Hydrochloric Acid
(HC1), Nitric Acid (HNO3), Ethylenediaminetetraacetic Acid (EDTA), acetic
acid (CH3COOH), and Calcium Chloride (CaCl2). Batcli soil washes and soil
column flushing experiments were conducted using a sandy loam (pH = 5.5,
CEC = 7.6 meq/100 g, K^ = 2.5 10'3 cm/sec) from Erie County, New York.
Batch soil washes were conducted using several concentrations of HC1,
HNO3, EDTA, acetic acid, and CaClj. Based on batch soil washing results,
0.1 N HC1, 0.01 M EDTA, and 1.0 M CaCl2 were selected as soil flushing
solutions. HC1 was chosen to represent a strong acid, EDTA was chosen to
represent a chelating agent, and CaCl2 was chosen to represent removal us-
ing an exchange solution. Following soil contamination and placement in
the column, flushing solutions were applied continuously at a constant rate
for approximately 5 to 8 pore volumes. Table 9.4 summarizes the percent-
age recovery of lead in the column tests and the number of pore volumes
required to achieve a significant amount of a final recovery (Reed, Carriere,
and Moore 1994; Reed, Moore, and Cline 1995).
Table 9.4
Results of Column Leaching Tests
Flushing
Solution
Tap water
0.1 HC1
0.01 M EDTA
1.0MCaCl2
Pb
no data
85% (5 pv)
@ 100% (5
pv)
78% (5 pv)
PbS04
0.5% (58 pv)
32% (58 pv)
@ 100% (58 pv)
96% (58 pv)
PbCOj
3% (10 pv)
97% (20 pv)
@ 100% (58 pv)
14% (58 pv)
Pb-Naphthalene
10% (58 pv)
78% (5 pv)
72% (10 pv)
no data
Adapted from Reed, Moore, and Clina 1995
-------
"I'll I 111 " 'I''
inn,' ' , jiiii 'i iiiiiH < imp
III. i ill'lii I' ', ' ,1
!' iiilf"11:, . i I
Many factors affect heavy metal retention by soils, such as soil type, cat-
ion exchange capacity, particle size, natural organic matter, pH, age of con-
tamination, and the presence of other inorganic contaminants. This study
revealed that using pump-and-treat technology alone to remove heavy metals
from contaminated aquifers is a highly ineffective process. Soil flushing
with proper flushing agents, in most cases, should enhance the remediation
process efficiency by one order of magnitude.
Cose 4 Surfactant-Enhanced flushing
of DNAPL Flushing Pilot test
j i ' f
A field test using surfactant-enhanced, pump-and-treat remediation (soil
flushing) of aquifers contaminated with dense nonaqueous-phase liquids
(DNAPLs) was conducted from June 1990 to August 1991 at the Borden
Canadian Forces Base near Alliston, Canada. The test was conducted in a 3
m by 3 m by 3 m (9.8 ft by 9.8 ft by 9.8 ft) "cell in a shallow, clear sand aqui-
fer. The test cell was created by driving sheet piling through 4 m (13.1 ft) of
water-saturated layered sand into an underlying clay aquitard. The cell was
contaminated with 231 L (61 gal) of tetrachloroethylene (PCE) using a shal-
low well located in the center of the test cell.
Three cores were taken from the lower portion of the test cell. There was
reasonable correlation of PCE saturation with depth between the cores. The
saturation distribution from a core located near the center of the test cell is
shown in Figure 9.5. Preferential migration is evidenced by differences in
PCE saturations with depth.
The upper 1 m (3.3 ft) of the saturated sand was excavated and replaced
with a confined bentonite layer prior to remediation. A line of five injection
wells was installed on one side"67iftie test cell. A line of five withdrawal
wells was installed on the opposite side of the cell. The injection and with-
drawal wells penetrated the entire depth of the sand aquifer. An aqueous
surfactant solution was circulated to the test cell using this system of
injection and pumping wells and the injected PCE recovered (Fountain et al.
1995; Freeze et al. 1995). The remediation process involved (1) direct
pumping of free-phase PCE, (2) water flooding to remove free-phase and
ill! ...... :
m,
9.12
-------
Chapter?
Figure 9.5
Measured PCE Saturation at the Location Near the
Center of the Test Cell Prior to Surfactant Flooding
198.75
198.25 -
197.75
197.25
196.75
196.25
10 20
PCE Saturation
O Measured ; .
Bass of diagram Is bottom of test cell
Reprinted wRh permission from Freeze et al., Surfactant-Enhanced Subsurface Remediation Emerging Technologies, ACS
Symposium Series 594, David A. Sabatinl, Robert C. Knox, and Jeffrey H. Harwell (ads.), p 194. Copyright 1995 American
Chemical Society.
dissolved PCE, and (3) surfactant flushing to solubilize additional residual
PCE. Table 9.5 summarizes the results of these tests.
The results of the field test suggest that use of surfactants in soil flushing
processes can effectively remove a large portion of DNAPLs in contaminated
aquifers. However, at Borden, the location of the DNAPL zone was known, as
was its contaminant, and was well confined in a homogenous environment. At
most hazardous waste sites, subsurface conditions are highly heterogeneous.
Detailed site characterization and laboratory study are required to design an
effective soil flushing program tailored to the site's specific conditions.
-------
If. I1 I If
;ป<
Ill II II
111 111 III
-1" '' fable 9.5 '
Summary of Presurfactant and Surfactant Soil Flushing Results
.'.:' PCE Recovered
Number of
(L) ; JR 'i I,*/'! !"' can ii>" i , *". ,,i Jl. I": - 'i ';:,
I iiiiiyiii1' in in as;,,."' -'i! iiiiiiitii ;>. ii.iV ;. i*ii.i! jt'iiB :",' ปi>
9.14
r !'. ii ,ti. i
~^4ป,.
-------
Chapter.9
100,000
80,000
60.000
1
40,000
20,000
Figure 9.6
Fairchild Site Cleanup
Total Water Pumped -13.2 billion gal (0.82 ppm3)-.
Xylene-4,180 Ib
IPA-25,300 Ib
TCA- 29,040 Ib
1982 I 1983 I 1984 I 1985 I 1986 I 1987
Year
The total contaminants extracted for all wells from 1982 through 1987 was 40,800 kg (89,760 Ib).
Case 6 The Savannah River Plant
Hazardous Waste Management
Remediation Project
The Savannah River Plant Hazardous Waste Management Facility
(HWMF) remediation project illustrates the potential benefit of applying
enhanced recovery techniques. The Savannah River Plant was part of a sys-
tem of weapons plants that conducted research and manufactured products
necessary for the maintenance of nuclear weapons. Solvents used in the
manufacturing process, namely, 1,1,2-trichloroethylene (TCE),
-------
>l> illliK .1 '"!' 'ill' !
<_ase Hisrories
Figure9.7
Hypothetical Projection of a Pump-and-Treat
Case Jo Emulate Cleanup of a Superfund Site
i Illis
;,Uf. /i! i
'iiiJ! :;;':ป' t'
:;"" Tlme(yr)
1
100
90
80
70
1 60
1 50
1 40
* 30
20
10
0
6 25 50
. , ,_., J..~..^... -
.
/S34.7 million
-X
I
j
I
F
-
1
3 50 100
75 100 12
3'
illion
ISO 200
Pore Volumes Treated
bNAPLs assumed initially In place: &700 kg tlzgoooib)
Time to reach 99.9% racovery: 127 yr, 202 pore volumes
Remaining after 99.9% recovery: 0.01 1 ppm
1 i1 ' ,' , , i " | .,!
'I" 1 ' , ,. 1,, '.", 1 'J ,ป:
: ,
ป N,
i1' 'i. . ". i ' II II
tetrachloroethylene (PCE), and 1,1,1-trichloroethane (TCA), were released
to the site's HWMF from 1952 through 1982 (US EPA 1992).
The discovery of contamination underneath the plant's HWMF in June
19811ed to a geologic and hydrologic investigation to define the scope and
range of contaminants at'the facility. The site assessment involved approxi-
mately 250 monitoring wells over a broad area.
The site is underlain by a wedge of unconsolidated to semi-consolidated
sediment. The formations of interest beneath the plant, in order of increasing
depth, are the Barnwell group, with an average thickness of 17 m (57 ft), mostly
vadose; the McBean formation, with an average thickness of 9 m (30 ft), mostly
saturated; and the Congaree formation, with an average thickness of 18 m (60
ft), saturated. The Ellenton formation, consisting of approximately 62% silt and
9.16
-------
Chapter 9
clay, serves as an effective lower impermeable boundary. The groundwater
level was approximately 18 to 36 m (60 to 120 ft) below the land surface within
the Barnwell group and the McBean formation.
The various permeable and impermeable layers were contaminated with
an estimated 211,045 kg (464,300 Ib) of organic degreasing solvents, includ-
ing TCE (approximately 75% of the total contamination), PCE, and TCA.
A pump-and-treat remediation program, consisting of pumping from 11
recovery wells, was implemented in 1985 to extract contaminants from the
groundwater beneath the facility over a period of 30 years (US EPA 1992).
From mid-1985 to December 1990, the average pumping rate from the re-
covery system was approximately 1,427 L/min (377 gal/min). The average
pumping rate was increased to 1,813 L/min (479 gal/min) in 1993. The TCE
concentration, measured in the air-stripping facility influent, was reduced
from 25,000 |jg/L to approximately 6,000 Hg/L, while the PCE concentration
decreased from 12,000 |ig/L to approximately 4,000 (Jg/L (see Figure 9.8) by
this pumping.
With the anticipated average pumping rate of 2,082 L/min (550 gal/min)
for a total of 1,094 billion L (289 million gal) per year, the projected total
fluid volume pumped from the aquifer in 30 years would be about 32.9 bil-
lion L (8.7 billion gal).
In the pump-and-treat process, the total volume pumped in relation to the
number of pore volumes is a key parameter in estimating the time required
to complete the remediation. At the Savannah River site, it was estimated
that one pore volume contained approximately 55.6 billion L (14.7 billion
gal) of water, assuming a dimension of 4.86 million m2 (1,200 acres) and
saturated thickness of 48 m (150 ft) and a porosity of 25%. Accordingly, it
was calculated that after 30 years of continuous pumping, at an average rate
of 1.09 billion L/yr (289 million gal/yr), less than one pore volume of water
would be withdrawn and treated from the contaminated formation. It would,
therefore, require approximately 50 years just to pump out one pore volume
of water. The pore volume pumped per year is only 2% of the total pore
volume (NRC1994). Given the low pumping rates, the distance between
wells, and the potential for detection of contamination outside the expected
zone of capture, it was concluded that it is unlikely that contaminant concen-
trations would be reduced to below health-based levels in a 30-year period
(DOE 1989).
-------
|L ]
': : 'i '4
i" .I*!11'!!!' ! . il
i ,1'injf,;11 * :,,,'i|
III' a::1!!!'1, ' ; V'< '" [it
I,,ill!,1 |i,i"f ,,,; : ,|.
"i, E-iti
ITI,
, 'In ซi ini ..... ..... H ;' mi /MIII 'iir1 din,1 i .11 i "inii,,",
"T -I ' '' ' -
i i ii i ii Figure 9.8
time-Concentrated Plot of TCE and PCE in the Air-Stripper Influent
at the Savannah River Plant Site
,i,,Eir iiiiwiiMi 'ii,ii', a ,. i' ii in
Influent Concentrations to Air Stripper
30,000
'" 1985 1986 1987 1988 1989 1990 1991 1992 1993
TCE
PCE
The NRC (1994) stated that for effective contaminant removal that "the
volume of water that must be extracted will generally be larger than the vol-
ume of contaminated water." In a conventional in situ sodium carbonate/
bicarbonate mining process, removal of 10 to 20 pore volumes are required
to restore the aquifer to previous mining levels. A range of 10 to 20 required
pore volumes suggests a 500 to 1,000 year remediation time (NRC 1994).
The number of pore volumes required depends greatly on sorption/desorp-
tion phenomena and aquifer heterogeneity. Sorption/desorption phenomena
retard the flow of contaminants and prolong the remediation time. There-
fore, if these assumptions are correct, it may take several centuries to clean
up the Savannah River Plant HWMF site.
Some options to speed up the remediation program include:
redesign and kcrease the flow capability of the air stripper;
ป redesign the wellfield so the pumping rate could be significantly
increased;
in, ,,iiiiiiii!ii"i|i;;, :t ..niiii1 jiiiiiit,:,, , ...... all ..... i: ! ..... ill uiiiifi ..... ;,,i>,j!!iii]iB ' .tiip , ijii-
........... ,
,:i,t ,>; ......... :,:i, ........ n ......
iji'i' (jii'ii ..... luii^^ ..... tff : ri. viisii ..... ii iiiii, ..... 'iii.:,:<,, ,' liii ,, ;
-------
Chapter 9
re-inject the treated water back to the aquifer. This would conserve
the resource and increase the pumping capacity of the wells;
apply the enhanced oil recovery technology, adding chemical
recovery processes (e.g., surfactants) into the recovery system to
increase the rate of contaminant removal and reduce the number
of pore volumes required; or
remediate vadose zone NAPLs to control percolation of contami-
nants to the water table.
Despite the fact that enhanced recovery methods offer significant prom-
ise, they have not been used at the Savannah River site.
Case 7 IBM Dayton, Ohio, Facility
Remediation Program
The International Business Machine Corporation's (ffiM's) Dayton, Ohio
facility produced punch cards for computer input and inked ribbons for
printers until 1985. In December 1977, a contaminated plume of organic
solvents was discovered in the groundwater system. The principal contami-
nants of concern were 1,1,1-trichloroethane (TCA) and tetrachloroethylene
(PCE). In 1978, IBM started a remediation program by operating a system
of groundwater extraction wells.
Two interconnected aquifers were involved in the groundwater remediation
program. The water table in the shallow, unconfined aquifer is generally 9 to
14 m (30 to 45 ft) below the ground surface, with a saturated thickness of
approximately 6 to 9 m (20 to 30 ft). The lower, semiconfined aquifer is
approximately 18 m (60 ft) thick and is bounded from below by an imperme-
able shale.
The suspected source of the contamination was near well GW-32.
During the well extraction program in 1982, nine injection wells were
added to inject treated water to the shallow aquifer in order to accelerate
the flushing process.
-------
ill I i II III
'"ii ,'IIMI . ,1. lif I
In 1984, IBM's consultants concluded that the groundwater extraction
system mat operated between 'jf^S'and" 1984 haci been successful in reduc-
ing the contaminant concentrations in the shallow aquifer (see Figures 9.9
and 9.10). The extraction system was subsequently terminated. However,
continuous monitoring indicated that the concentration of TCA and PCE in
the immediate source area had risen sharply (see Figures 9.9 and 9.10). The
reappearance of higher concentrations has been attributed to the presence of
DNAPLs in both the upper and lower aquifers. IBM's consultants have con-
cluded that this residual source of contaminantsi cannot effectively be re-
moved by groundwater extraction. IBM decided to resume extraction at
lower pumping rates with the objective of plume containment.
Examination of this case indicates two options that could be considered to
speed up the remediation process:
re-inject the treatedwater back to the shallow, unconfined
aquifer using horizontal injection wells and, thus, remediate
vadose zone NAPLs to control percolation of contaminants to
; , ; ;, ;;;;;; , ;,::: "i,1 * 3
the water table; and
add surfactant in the injection/extraction system to'significantly
increase solubilities of TCA arid PCE and, thus, enhance the rate
of contaminant removed, especially DNAPLs.
"II ,,' f" ; , '" ll,,1,lli'lll11, , '"I", ' If,, IKIfi O ' " I, If!' ,,i| ,|, ! II : ! Ill111" , : I,,!1 ' " I1'1"!!!1,1:'1!!"1 I1"' ' 'I :\ ' Llll,,11,, ll|l,,i,'l'',,ซ, 111,1'III ;lll if
!' ,' "In 'i ' '!' ,':l ' ,," t !,, l|' ill '.Sill! ,ll;il!,,i I1,' i"
111 IIP I
i-".,.' iilf'l
:"1! iil'li
,:'',,"ill!
''I j'..1 , ', 111"1'!,,,,, I ill ||
9.20
-------
Figure 9.9
History of TCA and PCE Variations in Extraction Well GW32 (Six Month Average Concentrations) at IBM-Dayton Site
<113,558
S8S8S8i88858ฃ-5S8S58888
TCA
OPCE
Source: DOE 1389
9
a
-------
:>:;ป 'iff In
j;:ป
is
ill '!|
1 !
I!! i S is
i: ! J :
! , ', ~If -.-.": 4 ^Iiise<; -- . - iiS :- -?.ฃ-'.
: : i '] It ii,!!l
Figure 9.10
History of TCA and PCE Variations in Extraction Well GW25 (Six Month Average Concentrations) at IBM-Dayton Site
350
,, .
l| ' 1 _' !ป
JJ JD JJ JD JI JD JJ JD JJ JD JJ JD JJ JD JJ JD JJ ID JJ JD JJ JD
78 78 79 79 80 80 81 81 82 82 83 83 84 84 85 85 86 86 87 87 88 88
TCA
OPCE
Source: DOE 1989
i ,*
i ;
t 4
-------
SOLVENT/CHEMICAL EXTRACTION
-------
i ill' !' l!",ni!, HI
, !!'.' ; ii '" j
i i i
II l| I |l IIIII II III 11 ll|l IIII I I III I ,!',; r IM Llvnli,l!l,' ,1. ' "KM, "Hi in! il ' i fliliil^^ II , I1 III, J 'iiiluilllliir iihlllll I ,n. III \ll!llilliliiili!'iliililllllll IP I
-------
Chapter 10
APPLICATION CONCEPTS
10.1 Scientific Principles
Solvent/chemical extraction (SCE) is an ex-situ separation and concentra-
tion process in which a nonaqueous liquid reagent is used to remove organic
and/or inorganic contaminants from wastes, soils, sediments, sludges, or
water. The process is based on well-documented chemical equilibrium sepa-
ration techniques used in many industries, such as oil extraction from soy
beans, supercritical decaffeination of coffee, and separation of copper from
leaching fluids.
SCE is differentiated from the soil washing technology described in previ-
ous chapters in that soil washing involves the use of water, dilute aqueous
solutions of detergents, or chelating agents to remove contaminants through
desorption, abrasion, and/or physical separation. Whereas, SCE relies on the
action of concentrated nonaqueous chemical agents.
SCE typically produces a clean fraction and a concentrated contaminated
fraction, which requires further treatment to recover, destroy, or immobilize the
contaminants. The process may concentrate contaminants by a factor as high as
10,000:1 (US EPA 1993); thereby significantly reducing the volume of material
requiring further treatment or producing a concentrated stream for materials
recovery. SCE effects the preferential separation of one oir more constituents
from one phase into a second phase. In classical chemical, engineering terms,
SCE is the term applied to the transfer that occurs between two liquid phases, or
between a solid and a liquid phase.
As shown in Figure 10.1, in a conventional liquid-liquid contacting sys-
tem, the solution to be treated is called the feed, the material to be extracted
is called the solute, and the liquid selected to separate the solute from the
-------
M ซซ! ซm it*'
m !! !!ltl!
SM ' I'
i,_ , . _ ; t-
.M *Ji
t>:
-.;.
,;
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Figure 10.1
General Schematic of a Standard Solvent Extraction Process
Clean
Solvent
, , Solvent
* 1 with Organic
;._; ;: Contaninants So!vsnt
./" -:: rvnhmm.^Medi. . Fซtr*1mป > Separation (Solute) Recoverv
.,,, ,; n%ซfl MI (ouUonai; (Distillation)
,-,, , ireeaj ID ^) [Extract] (4)
O -
5N3 '
Concentrated
?J (Solute)
'.--,.- : Clean
; s , Desoiptron Solvent
(Raffinate
1 * Strippuig)
- Decontaminated (3\
SoUdsplus
(Ragjnate)
Decontaminated
; :
1 I S Source: USERM9M
i i fc
-
m
-
- - ;" j
M ; : ^: =~ s;;:; I
: .: i
i ; ;-;=-: ; W . ,; j
: -i .,:."!..- i
:j: : U;=: M; :r;^ j
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i
: t : ' - - I
-: I.-.. .:_.... _ _ - :
; ! i ; I - = s i
: ; ; : 1 - ~- i
i i '. . . I . - = I
-------
Chapter 10
balance of the feed is called the solvent. The solvent-rich, solute-laden prod-
uct is called the extract, and the residual of the feed stream (from which
solute has been removed), is called the raffinate. The solute concentrations
in two contacting liquid phases, corresponding to equal chemical or thermo-
dynamic potentials, define the equilibrium state. The; ratio of these concen-
trations is the equilibrium distribution coefficient. Tliis is a measure of the
best separation or solute removal that can be effected. Where liquid-liquid
miscibility is poor (i.e., the solubility of each liquid in the other is less than
1,000 mg/L or 0.1% by weight) or merely partial, contaminant transfer is a
function of relative solubilities and the equilibrium di stribution coefficient.
For transfer between two liquid phases, the phases can be immiscible or
partially miscible. Maximum separation of contaminants is effected under
the following conditions:
the solute is much more soluble in the solvent phase;
the solvent phase is completely immiscible with the feed; and
the solvent has a substantially different specific gravity from that
of the feed.
In liquid-liquid solvent extraction processes, the extraction operation can
have one or more contact stages. A contact stage consists of three steps: (1)
combining the feed and solvent in a mixer or contactor, (2) allowing the
mixture to approach equilibrium, and (3) settling the mixture to separate the
extract and raffinate phases. Several such stages can tie combined in process
trains. Partially-purified feed can repeatedly be brought into contact with
fresh solvent, thereby reaching equilibrium states at successively lower sol-
ute concentrations. This design is referred to as cross-current extraction as
shown in Figure 10.2. Alternatively, stages that approach equilibrium can be
arranged in a counter-current flow mode whereby the final feed-side residue
(effluent) stage approaches equilibrium with solute-lean solvent. Counter-
current extraction is illustrated in Figure 10.3.
When a substrate is transferred from a solid to a liquid phase, the action is
called leaching. SCE is the controlled leaching of contaminants from soils,
sediments, and solid wastes through use of organic solvents or nonaqueous
liquids. Common examples of leaching are the recovery of a metal (solute)
from metal ore (substrate) by treatment with strong acid and loss of fertilizer
from crop land by runoff and percolation of incident rainfall.
-------
.Ill, "!|,:! L V.ili ,'1'",: I li T1,," "''"
nilllll
ill
.i-l! i j '.:'ซ!
I I
I'Ci , i. ill
Figure 10.2
Cross-Current Extraction
Fresh Solvent
'iiilll'jji'" i , T i' ' "!||||, ||i" i jniijii
ife |l":-: '. ;'-v'df fi
11"111!', ill, I iilJIIIM
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Figure 10.3
Counter-Current Extraction
'ซ i ".i ,'! ..:;!;,. Wia! illK I'ii;S;*iillj!*:';,i;!:!!';i-!V ',',' ' ill";, >,T r.tfliJ'"!!!!. !'
i, > ;;* .;;;.\'.-W <; -I I;1' !'''ซ! l''1'^ i" " "''' ' ปซ K' ' -! i *'' -.'
i il Feed I f Extracts
,. 'i||n.!l ,,! ..fiji,; j Final
_I i L
Stage 1 Extraction (Feed)
Raffinatel Extract 2
Stage 2 Extraction
Raffinate2 Extract 1
Stage 3 Extraction (Raffinate)
V.WT-I -f
Raffinate 3
Final j | Fresh Solvent
10.4
-------
Chapter 10
SCE processes used for soil and sediment cleanup typically employ a
solvent that extracts both water and organics into the liquid phase. Subse-
quent steps involve separating the liquid phase from the solids, separating
.the water and organic phases, and, finally, separating the contaminants from
the solvent. As such, the extraction of the contaminant from a solid phase
involves only the equilibrium of the contaminant with the solvent. Where
the solute is bound to a solid substrate, solubility of the solute in the solvent
is balanced by low-energy sorptive binding, high-energy chemisorption, or
incorporation in the solid matrix. The chemical potential of the solute in the
solid phase is a function of solute-solid interactions: weak van der Waals-
induced dipole forces versus strong hydrogen, covalent, and electrostatic
bonds. The stronger the interactive binding, the poorer the equilibrium dis-
tribution coefficient.
The capacity of a solvent to separate a solute from a weakly- or partially-
soluble liquid or solid is its selectivity and is determined by the following
equation:
Selectivity = (Mass Fraction X in E) / (Mass Fraction A in E)
(Mass Fraction X in R) / (Mass Fraction A in R) . ^ '
where: A = primary feed stream constituent;
E = solvent-rich phase;
R = residual phase (raffinate) at equilibrium; and
X = solute.
Selectivity must exceed unity; if it is unity, no separation is possible. If
"A" is water, as it is in oily wastewater, secondary sludge, sediment, or
wet soil, selectivity may determine whether the extraction technology is
applicable.
Most SCE processes employ solvents at near-ambient pressures and tem-
peratures during extraction. Typical solvents used individually or in combi-
nation are amines, alkanes, alcohols, ketones, and chlorinated hydrocarbons.
Solvent extraction can occur under three processing approaches. The
most common approach employs two phases in contact at ambient pressure
and temperature in which the solute is exchanged between a solid or liquid
substrate and a liquid solvent (at standard pressure and temperature). High
pressure and moderately-elevated temperatures can be used to create effi-
cient, dense solvents or supercritical fluids from substances that are gases at
moderate conditions (near-critical fluids). In some instemces, temperatures
-------
lillllnili i[. "; i;i, , i , T ' "; ' " in ' ' I
can be increased selectively to enhance solute transfer to a solvent phase
(critical solution temperature).
In the near-critical fluid/liquefied gas approach, butane, isobutane, pro-
pane, carbon dioxide, or other gases liquefied under pressure at or near am-
bient temperature are used during extraction. These processes take advan-
tage of the special properties of gases when they are near their critical tem-
perature and pressure (thei-modynamic critical point). At tliis point, the liq-
uid and vapor phases of the solvent, in equilibrium, become identical, form-
ing a single phase. A fluid near its critical point exhibits the viscosity and
difrusiyity of a gas, but also the solvent characteristics of a liquid. Under
these conditions, the solvent can effectively penetrate the solid matrix and
mobilize organic contaminants.
Finally, critical solution temperature SCE methods use solvents in which
solubility can be varied over the process operating temperature range. These
processes use liquid-liquid extraction at two temperatures. At the lower
operating temperatures, the fluids are miscible. At the upper operating tem-
peratures, theitwo fluids forrii separate phases. In these processes, solvent
.M!'1:;' ""|I; ' I . 'i'S .I,;*1!"1: " i ' ' recovery often consists of numerous unit operations.
1 o. 1.1 Development of Solvent/Chemical Extraction
Solvent extraction and leaching processes have been in existence for
llj-,' V ', p . . || ;i" :'| ' ' ' many decades, but only recently1 nave they been adapted for remediation
purposes. Within approximatelythe past 20 years, several technology ven-
dors have developed arid offered processes targeted at remediation activities.
Many advanced no further than "operation of a pilot plant or a prototypeT As
of the date of this publication, fewer than a half-dozen vendors offer com-
mercially proven processes, and only one firm appears to have developed a
financially-successful remediation business. Two firms offer similar tech-
nologies for non-remediation activities.
Three systems (CF Systems, RCC's B.E.S.T., and TERRA KLEEN) have
been demonstrated under the US EPA Superfund Innovative Technology
Evaluation(SITE) demonstration prograrii and are fully documented. Re-
sults of test programs and evaluations have been mixed. In a number of
cases, the systems have met or exceeded test objectives, while in other cases
they have riot. Therefore, for most applications, treatability testing is re-
quired to determine site-specific design parameters. Based on results of
10.6
-------
Chapter 10
treatability testing or similar applications, suppliers are offering systems for
a wide variety of applications.
i
10.1.2 Fundamental Process Concepts
The fundamental operating concepts, especially those employed in the
extraction step(s), vary widely depending on the characteristics of the sol-
vent employed. Four SCE processes are described in this section Amine
Solvent, Supercritical Fluid/Liquefied Gas, Drying/Extraction, and Conven-
tional processes. However, all SCE processes use an organic or nonaqueous
solvent to remove organic contaminants from soil, sediment, or sludge. Fur-
ther, SCE processes are designed to operate in either a batch or continuous
mode, but not both, and all employ relatively similar unit operations, as de-
picted in Figure 10.1. SCE generally includes the following operations:
feed preparation,
extraction, j .
solids and solvent separation, and
solvent recovery.
Contaminated soils, sludges, or sediments are excavated and enter the
feed preparation system, where they may be screened, crushed, dewatered,
and/or slurried depending on the particular SCE process being employed.
Chemical conditioning, such as pH adjustment, may be necessary to ensure
successful extraction.
The prepared feedstock is then transferred to the extraction vessel where it is
mixed with the extraction solvents); Extraction is carried out in either batch or
continuous mode in a single vessel or a series of vessels. Selection of the ex-
traction solverit(s), the solvent-to-solids ratio, the extraction contact time, and
the number of extraction stages depend upon the specific contaminant and na-
ture of the feed. These parameters are typically determined during treatability
studies. Important solvent characteristics include relative solubility of the sol-
ute, immiscibility with the feed, specific gravity, toxicity, flammabiliry, physical
properties, chemical reactivity, ease of recovery for recycling, and cost.
Feed and solvent streams can enter a continuous contact system in paral-
lel-flow or counterflow configurations. In the counterf low arrangement,
relatively clean solvent contacts solute-lean raffinate, while feed contacts
-------
I
if,, ' ;
'"'I " 111, f '"".' ' ป!',!
V " 1 1
-.'I !,l
I ''i .. ' ii; '.i:!':! :"" I
in i' ,,">i:ii
solute-rich extract. This permits both end-state pairs to approach equilibrium.
The effluent streams in a pairalletfiow configuration can also be caused to ap-
proach equilibrium through use of multiple extraction stages. In both cases, the
solvent is selected to "maximize' tfie solute distribution coefficient.
, > : ; .rjr.'.juii i '!".'.r '!?ijii:" *"; ": I|I|ป|:H:*!!' ;, ,:;,
-------
Chapter 10
This principle works by mixing the feed with solvent to create a fluid
phase. The fluid phase contains amine and aqueous phases that are partially
soluble in each other. This solution solvates the contaminants that were
present in the feed. Unlike other solvent extraction systems where extraction
efficiencies are hindered by emulsions that partially occlude the solute,
amine solvents can achieve intimate contact with solutes at nearly ambient
temperatures and pressures. Therefore, the process can treat feed mixtures
with high water content without loss of extraction efficiency.
Once extraction of the feedstock is complete, the solid portion of the
feedstock is removed from the solvent by gravity settling and/or centrifuga-
tion. The solvent/water/oil mixture is removed from the solids and subjected
to additional processing. The solids are dried to remove residual solvent.
Processing the solvent/water/contaminant mixture begins with separating
it into its components. The solvent and water are removed from the mixture
by evaporation and condensation. The resulting solvent/water mixture is
then in the temperature range (27ฐC to 80ฐC [SOT to 176ฐF]) where the sol-
vent and water are only partially miscible. With the specific gravity of the
solvent at 0.72 as compared to water at 1.0, the solvent and water are easily
separated by decantation. The traces of residual solvisnt that remain in the
water (about 2% by weight) are removed by steam stripping.
After the solvent/water has been removed from the contaminant, the con-
taminant fraction can be destroyed. An added benefit: is the simultaneous
extraction of other organic compounds that may be present in the feed, leav-
ing the residual solids free of contaminants that may contain other regulated
constituents such as PAHs.
A process-flow schematic for a mobile amine solvent extraction unit de-
signed to extract PCBs, PAHs, volatile organic compounds (VOCs), and
pesticides from excavated sludges, soils, and sedimenits is presented in Fig-
ure 10.4. Four basic operations are involved extraction, solvent recovery
and contaminant polishing, solids drying, and water stripping. A description
of the major process units follow.
Extraction/Dryer. The extractor/dryer vessel is used for extraction, solids
settling, solids/liquid separation, and solids drying. The extractor/dryer is
equipped with horizontally aligned mixing blades and is surrounded by a
steam jacket. The vessel is also equipped with direct injection ports through
-------
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!
1 1
,
a ?
s
= =
111 -- _: [ fit, 'fri* '-': ' gjj -f '- - < : i ซ i i ii ':'::>' \ \
n',\ - ', ' ; :: : ; -~:i:S" - " ; i , r
ii ; ',,\,, ; ; ; IK iii: r. ^SMSB; ' ;,;,ซ; ;n p s ; i ;:
: , : : .;., ,;:; . :
1- ' ' :-.'
: Figure 10.4
p / Generalized Diagram of the RCC B.E.S.Iฎ Solvent Extraction PK
t Primary Extraction/ Secondary Extraction/ Solvent Storage Solvent Separation
; Dewatering Solids Drying
; ' - Filter
* Cake
[; i Sbdge^-j j
VI/ i ' 1
, ,,,, |Premil% 1 "
; = i1 (link J I r_._!ซs._n 1 ( nil \
OC ^r-S - >l L ฃ-J ^Decanter } 1
O ' ' 1 i
* *
MV -;.: -- -1
i 1 , i j | >j Exiractoa'Dryer 1 ฃ >^
l l Clean | 1 1 Clean Solvent f*-=
- -- - - Solvent 1 Solvent !< Makeup i ( Solvent N
i'i= 7 " W 1 - ^ ^ (.Decanter;
: aeanSolids 1 1 '
! ! " : Product A i
s -. Cold Wash Solvent N__.xl
i 1 Water
= jReceiver
3C6SS
Solvent Recovery
i
i * Solvent . - i
Evaporator : ;
i-: ; :
. = : . . .
'
* Water
Snipper
*n - -, < .-. -
^7 "^ ^
V 1 c :
j WaterProduct
j= ซ Source: US EPA1 993 ' " '
1= - - : : |, i --.--i.
%
D
O
!
i
==' I1
lg - h---
i|: irs
M i' a ; i
iiS
-------
Chapter 10
which steam is injected into the jacket to provide heat during extraction,
solids drying, and residual solvent removal.
Decant Tank. Following each extraction stage conducted in the extractor/
dryer vessel, the liquid fraction is decanted and directed to a decant tank (not
shown). This vessel serves as an equalizing tank to enable a uniform feed
rate to the centrifuge and the solvent recovery system.
Centrifuge. Liquid and fine particttlate stored in the decant tank are con-
tinuously fed to the centrifuge which removes any particulates that have
been carried from the extractor/dryer during the decant process. The centri-
fuge cake is directed to the solids tank (not shown) and the liquid, or
centrate, is directed to the solvent evaporator.
Solids Tank. The centrifuge cake is stored in a solids tank and reslurried
with clean solvent, The reslurried fines are then directed back to the extractor/
dryer prior to processing the next batch of material.
Solvent Evaporator. The solvent evaporator is used for solvent recovery
and contaminant concentration. The solvent/water azeotrope formed during
heating is evaporated from the concentrated contaminants. All vapors that
leave the solvent evaporator are condensed and transferred to the solvent
decanter. The concentrated organic contaminants are removed from the
system for disposal and dechlorination.
Solvent Decanter. The solvent decanter is a vessel used to receive and
separate the condensed solvent/water mixture from liie solvent evaporator,
extractor/dryer overhead, and water stripper overhead. The solvent decanter
is maintained above the solvent/water miscibility temperature, allowing
separation of the solvent and water phases. The solvent phase contains ap-
proximately 2% water by weight, and the water phase contains about 2%
solvent. The solvent phase is directed to the clean solvent tank for reuse in
subsequent extractions. The water phase is directed to the water receiver.
Clean Solvent Tank. The clean solvent tank stores the clean, recovered
solvent. Solvent from the clean solvent tank is transferred to the extractor/
dryer vessel to conduct subsequent extractions.
Water Receiver. After solvent and water have been separated by gravity
in the solvent decanter, the water phase, which contains about 2% solvent, is
directed to the water receiver. The water receiver stores all contact water
used in the process and provides feed for the water stripper.
-------
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>
ill1', LM '.."HI1
Water Stripper. The water stripper is used to remove residual solvent and
omer volatile compounds from the water recovered by the process. The
water stepping column isfa simple packed column, requiring few equilib-
rium stages. Distilled water Is recovered as 'the bottoms product and the
overhead solvent vapor is condensed and directed to the solvent decanter.
Typical solvent residuals in the effluent water stream are less than 2 mg/L.
I
.Vent System. An atmospheric vent discharge from the process is used to
eliminate noncbridensable gases from the various condenser systems to pre-
vent reduction of heat, transf:erefficiency. Normally, this vent gas consists
primarily of nitrogen purge gas with traces of oxygen and other atmospheric
gases. Most of the solvent vapors present are condensed by the refrigerated
vent condenser. However, to ensure that all organic vapors, including the
solvent, are recovered, a vent scrubber and an activated carbon adsorption
system are installed on the vent system outlet. The carbon adsorption sys-
tem consists of two activated .carbon beds connected in series. The primary
(upstream) carbon bed outlet is monitored for organic vapors, and a second-
ary carbon canister (downstream) is installed in case breakthrough of the
primary canister occurs. The carbon adsorption system ensures that there is
no release of organic vapors from the process.
10.1.2.2 Supercritical Fluid/Liquefied Gas Processes
Other vendor? specialize in the development and application of
supercritical fluid and liquefied gas extraction processes for chemical
production and hazardous waste treatment (Meckes et al. 1997). These
processes use liquefied gases as extracting solvents to separate organic
contaminants from wastewater, sludge, and contaminated soil. Target
contaminants include hydrocarbons (benzene, toluene, xylene, and other
constituents of gasoline), oil and grease, partially-oxidized hydrocar-
bons (phenols, alcohols, fatty acids, acetone, etc.), and chlorinated spe-
cies (PCBs and dichloroethane). Carbon dioxide (CO,) is generally used
1 " '^ !i"?' !!+ ,.| I1' lll;.Mfl|J ll"'.flili , ,";;; , ,|IN f ,i |IL; ,',j||l|i !. ,| ly,,|li,, r; ,11 " "|, % , 2' , *-',,, ,, J,
for aqueous solutions; propane is often selected for sediments, sludges,
and soils. In selecting the solvent, the solubility of CO2 in water and the
effects on pH and soluble inorganic salt content must be considered.
Propane is a volatile, flammable hydrocarbon that can constitute a fire
and explosion hazard in the event of system malfunction.
Figure 10.5 is a simplified diagram of a one-stage solvent extraction pro-
cess employing liquefied propane. Contaminated sediments are fed top
J IL.', ! ' " ' C . "" ; i S!:,: "x:,t ' :, ' - . Kill
[iff'' : ' I-. * "jliii: ,?]' | , ' :', , ':. , ! i, ,. , !" ,10.12
-------
Chapter 10
Figure 10.5
Process Diagram Supercritical Fluid/Liquefied Gas Process
Contaminated
Sediments
Concentrated Contaminants
and Natural Organic Matter
Source: US EPA 1990a; Donnelly et al. 1995 (modified)
down into a high-pressure contactor. Compressed liquefied propane at 20ฐC
(70ฐF) passes upward, counter to the solids, and dissolves organic matter.
Clean sediment (raffinate) is removed from the contactor. A solution of
organic contaminants in propane is passed to a separator via a pressure re-
ducing valve. Propane is vaporized, recompressed, and recycled to the
contactor as fresh solvent. Contaminants and natural organic matter are
removed from the separation vessel and recovered for disposal or reuse.
The process has seven basic operating steps. Initially, slunied sludge is
fed to a stirred-tank extractor (raw sludge may require pretreatment to elimi-
nate oversized material or to modify chemical characteristics, such as pH).
Propane is compressed to operating pressure, condensed, and fed to the ex-
traction vessel to dissolve oil in the sludge feedstock. A mixed stream is
taken from the contactor to a decanter in which gravity sieparatipn of the
heavier water and solids fraction and the lighter propane and oil fraction
-------
ved!
I
<"!' . ' ILi i
Ill 111 111
111 "'ill
It'
111,
occurs. Water and treated solids are removed from the decanter; the solids
are dewatered and the final filter cake is removed to a landfills.
Propane and oil pass to a solvent recovery still system which includes a
distillation tpwen The; distillation.tower; operates at a reduced pressure. The
reboiler is heated with recompfessed propane vapor. If the process is being
employed to treat petroleum refinery waste streams, the recovered oil col-
lected as still bottoms can be recycled to the refinery, and the propane is
recycled as fresh solvent.
The one-step mixer/settler system shown in Figure 10.5 is actually oper-
ated as a multiple-stage process. The number of stages must be suitable to
achieve Best Demonstrated Available Technology (BOAT) standards fbir
hazardous petroleum refinerywastes^048-]K:052)prescribed by the US
EPA (Office of the Federal Register 1996). The number of stages required
(typically two to five) is dependent on the feed matrix and type and level of
contaminants present. The treated oil and solids raffmate stream from the
commercial unit is claimed to conform to BDAT standards for 16 specific
volatile and semivolatile organic compounds.
I
The same concept can be applied with supercritical carbon dioxide or lique-
fied light hydrocarbon gas mixtures as the solvent. These modified processes
have been evaluated at bench- and pilot-scales (Meckes et al. 1997).
,,'S1" " ' ' .!"!ปi" ซ !' "'"" ' " . "",'ii' 'ill! ill! a i,'1" "'i'1 | I1,!, II ! I '" ' i,'1 JT ' ,:' . '",, "i, ' :!'"',, PL 'I1 "1 ""III!1'1, I:,.1"!
10.1.2.3 Drying/Extraction Process
A unique process employing SCE has been developed by another vendor.
The process separates mixtures into solids, oil, and water while extracting
organics using a carrier oil or solvent (US EPA 1992a). In instances where
heavy metals are complexed by organics, some metals may also be removed
from the solids (US EPA 1990b). Treatment effectiveness can be increased
by adding evaporation and extraction stages.
The process has been variously described as extraction (Trowbridge,
Holcombe, and Kollitides 1991), drying (Laii 1991), steam stripping (Haz-
ardous Waste Consultant l99l), and evaporation. It has been characterized
by the US EPA both as a "solvent extraction process" (US EPA 1991a) and
"other physical treatment" (US EPA 1991c). Because the main treatment
steps involve solvent extraction arid water evaporation stages, ffie process is
addressed in this monograph. It should be noted that trie carrier solvent may
be used in the very first stage or it may be mixed with the waste in later
10.14
-------
Chapter 10
evaporation and extraction stages after some evaporation has already oc-
curred (US EPA 1992a). As well as serving as a medium for the extraction
of organic contaminants, the solvent aids in maintaining the waste in a slurry
state as water is evaporated. The process consists of seven steps as shown in
Figure 10.6 and described in the following text.
Pretreatment. (not shown) Debris is separated from the feed, and if nec-
essary, the feed particles are ground to sizes less than 6 mm (0.25 in.).
Feed Slurtying (Fluidizing). The feed material is slurried in a fluidizing
tank with a carrier oil or solvent to extract indigenous oils and soluble organics.
In general, the solvent-to-feed waste solids ratio varies from 5:1 to 10:1 by
weight. The exact solvent to be used depends on the sits, but a hydrocarbon-
based solvent with a boiling point around 150ฐC (300ฐF), typically, alcohols or
food-grade mineral oils, is used for hydrocarbon- or organically-contaminated
solids (US EPA 1992c). The product of this stage is a slurry mixture.
Figure 10.6
Process Schematic Dryer/Extraction Process
Contaminants
Source: Donnelly et al. 1995
-------
fit hlilHi !" i Uiill
,,ii I IIWIPII: ", f
1 III Illllll I I 1 bill! i i I
ill
.a !"ป!ป :,:, 'I*1' '"Jill
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of' , t1" ., ,ii lit" ,. ill '! ,
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illlilill: TO
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Evaporation and Solvent Extraction Stages. The water in the slurry is
evaporated. In general, two to four multi-effect Evaporators are used in
commercial systems to evaporate the water (US EPA 1992c). Alternatively,
mechanical vapor recompression may be used (Holcombe and Kottitides
1991). For example, the evaporative stages can employ successive boiling
chambers, each operating at progressively lower pressures (Environment
Today 1991). This allows succeeding chambers to use less energy to vapor-
ize the water. Removal of the water aids in breaking emulsions, thereby
increasing organic extraction. At the same time, steam generated in the
evaporation system removes water and volatile compounds from the waste-
solvent slurry (Environment Today 1991; Hazardous Waste Consultant
1991). The heat also destroys microorganisms. The products of these stages
consist of vapors and a water-free slurry of solids in the carrier solvent.
Condensation and Oil and_ Water Separation (Vapor Treatment). The
vapors from the evaporation step are condensed. The water, carrier oil, and
solvent condensate are then sent to an oil-water separator (decanter). The
decanting separates any carrier oil and solvent and water-immiscible sol-
vents from the water.
The recovered water contains some residual solvent and low-boiling point
water-soluble compounds. However, the water is generally relatively clean
and virtually free of solids and can usually be treated with standard wastewa-
ter treatment technologies. Any recovered carrier oil can be recycled to the
fluidizing tank. The vent gases can be treated for residual organics by
granular actiyated carbon (US EPA 1992a).
Centrifuging (Water-Free Slurry Treatment). The majority of the carrier
oil and solvent is separated from the feed solids by centrifuging. The solids
may then be reslurried with clean (recirculated) solvent for additional extrac-
tions or directed to desolventization. The concentrate (from each extraction)
generally consists of the carrier solvent (with extracted indigenous oil and
organics) and approximately 1% fine solids. The centrifuge cake generally
consists of 50% solids and 50% solvent with extracted organics.
ป ' , ..-'i,',
-------
Chapter 10
More recent studies have used nitrogen gas to strip the solids (US EPA
1992e). The resulting offgas is then scrubbed to remove carrier oil/solvent
and recirculated. The vent gases can be treated for residual organics by
granular activated carbon (US EPA 1992a). Most of the heavy indigenous
oils in the centrifuge cake will remain with the solids in the centrifuge cake,
rather than evaporate (US EPA 1992c).
Distillation of Carrier Oil/Solvent (Treatment of Concentrate). The
used carrier solvent is distilled to recover the carrier oil and solvent and
separate the indigenous oils and organics. Products of this step consist of a
recovered solvent (substantially free of contaminants),, which may be reused,
and concentrated streams of light and heavy organics, which may be inciner-
ated or reclaimed.
10.1.2.4 Solvent Leaching Process
Another vendor offers a process that is similar to the "generic" version
described at the beginning of this section. It employs up to 14 organic sol-
vents in treating contaminated solids. The solvents to be used in extracting
organic contaminants from a particular waste stream are determined through
a series of bench-scale treatability tests. The solvent is selected based upon
the solubility characteristics of the contaminant(s) and its phase separation
characteristics with respect to the solid matrix (Cash 1991).
As shown in Figure 10.7, contaminated soils are loaded directly into ex-
traction vessels by a front end loader or by a conveyor system. The vessels
are covered, and clean solvent at ambient temperature and pressure is
pumped into each one. Organic contaminants in the solids are mobilized by
the solvent without the aid of a mixing device. Contaminated solvent then
flows into a sedimentation tank (clarifier) where settleable solids are sepa-
rated by gravity from the solvent. Clarified solvent is pumped through a
microfilter which removes fines, and then through a proprietary solvent puri-
fication unit which concentrates the organic contaminants. Clean solvent,
discharged from the purification unit, is stored in a holding tank for reuse.
This sequence of treatment steps, known as an extraction cycle, is repeated
until contaminant concentrations of the solids within the extraction vessels
are reduced to a desired level. At this point, the extraction vessels, and all
solvent carrying lines are drained, and the suction side of a centrifugal
blower is connected to each vessel's solvent discharge line. Much of the
solvent retained within a vessel volatilizes as air is rapidly drawn through it
-------
1 =TC mk^ f
i HI
; i ^ s
- - , j ;ซi .* i,
^* =? _a ซpfc^ =.=:,=
!i
:ป --*
ซi B:
ป ซ-^: a"1" M -*'ป : "
Li
! !l Mi
i
:
; Figure 10.7
Process Schematic Solvent Leaching Process
i ITon ITon llbn ITon ITon
! ' Contaminated SoU Contaminated Soil Contaminated Soil Contaminated Soil Contaminated Soil
- ^ ^ v ^ ,r ^ u v @,f -v v
TankA TankB TankC TankD TankE
Solvent Extraction Solvent Extraction Solvent Extraction Solvent Extraction Solvent Extraction
i , and and and and and
? Biological Treatment Biological Treatment Biological Treatment Biological Treatment Biological Treatment
ฑ Contaminated Contaminated
H Solvent > - - _ , , ,. Solvent
VentGas
A ;
1 ... .. ! Fillratinn
Vapor 1 , Unit
1 ' Sedimentation .Purification Y . Jpivent ,,
Tank * * Station * sฃ?
^
nk
:
i :- > Contaminated soil
' . >-WashsoIvent
! r">- Air and solvent vapor
:. (si)(S2Xง3) Sample locations
1 : i Source: Meckes, Engle. and Kosco 1996 M
h - -
| , :
ฃ ,*
1 fs
T ;.:.'
0
-------
Chapter 10
by the blower. Vapors discharged by the blower are passed through a con-
denser where spent solvent is recovered as a liquid which is then filtered and
processed through the purification unit. This recovered solvent is returned to
the solvent storage tank for reuse.
Some solvent remains associated with the treated solids following vapor
extraction. Further reduction of this residual solvent is effected through
biodegradation. This is accomplished by adding a mixture of water, nutri-
ents, and microorganisms to the soil in each extraction vessel. Biodegrada-
tion of the solvent is permitted to continue until residual solvent concentra-
tions have been reduced to acceptable levels for land disposal (several days).
Treated solids typically are removed from the vessels by a front end
loader and returned to the site. Contaminants concentrated by the solvent
purification process are removed and disposed off-site in accordance with
applicable regulations. Purified solvent may be used for treatment of solids
at other waste sites.
10.1.3 Soil Characterization
SCE differs from soil washing in that performance is not as sensitive to
the particle-size distribution of the soil or sludge being treated. Certain
types of soil washing processes are not effective when the feed is predomi-
nantly clay or silt. In general, this is not the case for SCE because contami-
nants are mobilized using a solvent system, whereas for soil washing, some
systems require separation of large particles from smaller particles. Never-
theless, characterization of the feed is important to assesss process feasibility.
As with most ex-situ remediation technologies, objects greater than a
certain size are usually removed to facilitate transport though the process
equipment. Clumps of soil or sludge are broken up to minimize mass trans-
fer resistance. One process calls for removal of particlf;s greater than 6 mm
(0.25 in.)(Meckes et al. 1997).
Most SCE processes employ a filtration step to separate, at least in part,
the solvent from the treated feed. Because a high percentage of clay or silt
could hinder this step, it is important to know the particle-size distribution of
the feed.
Some solvents tend to form emulsions with certain feeds. Therefore, tests
to identify this tendency are sometimes included in initial characterization of
a feedstock.
-------
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I, llilf1 : : I.,! 'i Ml i r
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uri 'i *' ' ,r '; ' it i
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Water content of the feed is important for some processes and in any
event must be measured to determine a material balance. Most processes are
limited to a well-delineated range of feed solids/moisture content. This may
necessitate a dewatenrig and drying stage In some processes and a slurrying
stage in others.
The pH of the feed should also be measured as some processes have lim-
its for this parameter.
10.1.4 Contaminant Occurrence
,' , :;'ซ;, .: i"' ,j' ::*<> W,M !i^!iMS 'X Rl/j.l lt:'iil:iii ',;,:;i ^l!!.;''.. '": ;ซ: *:i T,'i 'ill' IS /<
For all practical purposes, organic compounds, as opposed to heavy met-
als and cyanide, are the only contaminants for which SCE processes are
effective. The range of organic contaminants that can be treated is discussed
in Section 10.2. Potential feeds must be characterized to determine the total
spectrum of contaminants to be treated. This will, in turn, determine
whether SCE will be an effective treatment approach and whether it can be
employed for a total solution or must be used in combination with other
treatment technologies, such as chemical oxidation or stabilization.
10.1.5 Treatability Study Considerations
Treatability studies are principally modeled after the US EPA's interim
guidance document, Guide for Conducting Treatability Studies Under
CERCLA, Solvent Extraction (US EPA 1992b). The conditions for use of
the guide and the approach to be taken in using treatability testing to evalu-
ate an SCE remedy are the same as those described for soil washing (refer to
Section 3.2.2.3). It is extremely important to work with technology vendors
when conducting treatability studies.
As with! soil washing, a well-planned and carefully executed treatability
study is a critical element of a successful SCE remediation project. Such
studies are carried out at either the bench- and/or pilot-scale. They are used
to verify the applicability of SCE for the particular remediation under con-
sideration. They also provide data to determine the number of extraction
stages to be employed, to identify pretreatment and posttreatment require-
ments; to estimate full-scale maximum batch sizes, processing times,
throughput rates, and, hence, treatment costs and other aspects of the prdcess
design or configuration. Some vendors have developed mathematical
10.20
-------
Chapter 10
models for their processes, and the input parameters for such models are
obtained from treatability studies.
The primary focus of a treatability study, especially at the bench-scale, is
usually the extraction step. Other operations, such as (solvent evaporation,
water stripping, and solid/liquid separations, can be selected or designed
from first principles. However, pilot-scale studies often include studies of
these ancillary operations.
10.2 Potential Applications
SCE has been shown to be effective in removing semivolatile organic
contaminants from numerous substrates. Other possible applications under
study and development use SCE for the removal of VOCs and metals. This
section discusses appropriate applications and limitations of the technology.
10.2.1 Matrix Types
Contaminated soils, sludges, and river and harbor sediments have each
been successfully treated using SCE processes. Specific characteristics of a
given matrix, such as particle size, moisture content, and total organic con-
tent, affect the extraction process. River and harbor sediments, sludges, and
soils with a high fines (>30%) and moisture content (>30%) can be effec-
tively treated by SCE processes; however, it may be more cost-effective to
reduce the contribution of fines with size separation equipment and/or drying
the solids prior to extraction. Alternatively, a critical solution temperature
(CST) or hydrophylic solvent can be used during the first extraction cycle to
dewater solids. Solids with high total organic content (>10%) require more
extraction cycles to meet a given cleanup goal than solids with low total
organic content (<10%).
10.2.2 Contaminants and Mixtures
Contaminants at hazardous waste sites may be from a single source, such
as a spill, or they may comprise a mixture of contaminsints as is the case
with many uncontrolled dump sites. SCE systems are effective in removing
many of these contaminants and contaminant mixtures from solids.
-------
" ii'!, fiUIIll'1 1l/jilllllliliinlilllif!I1;1,,, I'iPliilH li'l&i'"
,.,' HIi1,1 * I1'1"!1'" '' ' 13 !
I1K ........ i
Illi JIIIIHI'ia1'":, 1" 'TjlLllj1 . ', I, if
'!{>,< SJtiRll' ,! ! ..... "I"1' I"- ' , ill: : - tilT '
i: :*' ...... i;'":.
iii 'Him; mi ?., i,
t lint":,
i. iiii,;|:ป
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Table 10.1 shows the effectiveness of SCE on general contaminant groups
for soil, sludges, and sediments. Note that some claims have been made
regarding reduction of metals using specific solvents; however, such claims
have not been substantiated in the field.
10.2 J "Site TVpes " ' ............. ; .............. ............. ........................... ; .................... ............
SCE has been successfully used to treat wastes from the following
types of sites:
river and harbor sediment sites (fose 1987; Meckes et al. 1992;
:" " ; ' ' US 'EPA I99*6a;); ................. " ' : .............. ' ...... ..... "" .......... '" ' ........... "" ........ "" " ............ """ ' ..... " ..... ' ..... ' ' ' " ............... ' ....... .................................... '' .........
i 'I"" I1 :, 'III!1 i .mi H" !i,il ....... n,.: I1 "il!i *. il:i:.i, MiBiPlllll'i'1 ..... ...l i<"l!lii'ปii|, ,i
-------
Chapter 10
Table 10.1
Effectiveness of Solvent Extraction on General Contaminant
Groups for Soil, Sludges, and Sediments
Effectiveness
Contaminant Groups
Soil
Sludge
Sediments
Organic
Halogenated Volatiles
Halogenated Semivolatiles
Nonhalogenated Volatiles
Nonhalogenated Semivolatiles
PCBs
Pesticides
Dioxins/Furans
Organic Cyanides
Organic Corrosives
Inorganic
Volatile Metals
Nonvolatile Metals
Asbestos
Radioactive Materials
Inorganic Corrosives
Inorganic Cyanides
Reactive
Oxidize rs
Reducers
* Demonstrated Effectiveness: Successful treatabllity test at some scale completed.
* Potential Effectiveness: Expert opinion that technology will work.
ฐ No Expected Effectiveness: Expert opinion that technology will not work.
Source: US EPA 1994
-------
Pretreatment typically consists of screening and/or crushing operations to
reduce the size of particles entering the extractor. Some vendors recom-
mended a maximum particle size of approximately 0.6-1.3 cm (0.25-0.5 in.)
in diameter (Meckes et all 1992).
The need for wastewater treatment is normally determined based on site
restrictions. Direct discharge to a collection system for a publicly-owned
treatment works (POTW) is preferred. If this is not available, on-site treat-
ment consisting of filtration and/or carbon adsorption or more advanced
treatments may be required.
Similarly, control of gaseous emissions from distillation or evaporation
equipment may be required depending on site-specific requirements. Activated
carbon can be effective in removing solvent vapors from such emissions.
Solids discharged from an SCE system may not be free of contaminants
of concern. Most currently-available SCE systems are designed to remove
organic contaminants from solids". However, mixed wastestreams may also
have high levels of hazardous metals. Such metals may be removed via soil
washing. Alternatively, the solids may be mixed with appropriate agents for
stabilization.
The concentrated extract is typically removed and treated off-site by in-
cineration or dechlorination. However, on-site incineration could be in-
cluded as part of a treatment train if not cost-prohibitive. Also, in the case of
chlorinated hydrocarbons, it may be possible to treat extracts on-site with
dechlorination technologies such as base-catalyzed dechlorination.
10,24
-------
Chapter 11
DESIGN DEVELOPMENT
7 7.7 Remediation Goals
For solvent/chemical extraction (SCE), the goal of a remediation project
is typically removal of one or more organic contaminants from a sludge, soil,
or wastewater. Removal of other types of contaminants (for example, re-
moval of metals by adding metal chelating agents to the solvent) has rarely
been practiced on a commercial-scale.
11.1.1 Proven Performance
SCE processes have been selected by the US EPA for some Superfund
sites contaminated with organics such as polychlorinated biphenyls
(PCBs), volatile organic compounds (VOCs), and pentachlorophenol.
The SCE processes discussed herein were developed to treat a wide
range of organic contaminants in several different matrices. See Table
11.1 for a summary of the types of contaminants removed in bench-,
pilot-, or demonstration-scale testing. Development of these processes
has typically proceeded from a design addressing a particular problem
(for example, PCBs in sediments) to a more general design capable of
treating a wide range of contaminants and matrices.
One vendor, employing an amine solvent-based process, has reported
results for treatability tests on soils, sludges, and sediments contaminated
with PCBs, PAHs, pesticides, and other semivolatile and volatile organic
contaminants (US EPA 1992c). The results show that the highest removal
efficiencies were achieved in treating solids that had high initial concentra-
tions of organic contaminants. However, in many cases,, the treated solids
retained a significant amount of the initial contaminant. For example, tests
-------
Ill " , ,i,! il , in'! 4,1
of three harbor sediment samples contaminated with PCBs in concentrations
of >20,000 mg/kg resulted in removal efficiencies of >99.8% after three
extraction stages, but residual PCB concentrations in the solids ranged from
27 to 720 mg/kg. Therefore, treatability tests should be conducted before
selecting SCE for site remediation. On the other hand, treatment of two
sediment samples with initial PCB concentrations of 427 and 425 mg/kg
resulted in removal efficiencies for both samples of 99.6.% and residual PCB
concentrations in the solids of 1.6 and 1.8 mg/kg or an average of 1.7 mg/kg.
- . ./. .,: : Tqblฉ 11.1
Potential Applications of Commercial
Solvent/Chemical Extraction Processes
Contaminant "type
PCBs
PAHs
VOCs
., ." Seml-VOCs
Pesticides ,
Matrices Tested
Soils (sands, loams, clays)
Sediments
Sludges
Slurries
Wastewaters
Drilling cuttings
I!,.1 "i , Si!? l',,,,.."1,,il'1S,, ', ,ii< " -" f"1: i
Pentachlorophenols
'.m.''.' ,.,r.","^,
Dioxins
Diesel fuel
Petroleum Hydrocarbons
Petroleurn-lisjed wastes M
KoS-KOXZwastes'"
RCRA waste codes:'
Water Treatment Sludges K044
Dissolved Air Flotation (DAF) Float K048
Slop Oil Emulsion Solids K049
Heat Exchanger Bundles Cleaning Sludge K050
American Petroleum Institute (API)
Separator Sludge K051
Tank Bottoms (leaded) K052
Source: Donnelly et al. 1995 and Office of th8 Federal Register 1996
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Supercritical fluid or liquefied gas SCE technology is used to remove
organic contaminants, such as hydrocarbons and oil and grease, from waste-
waters, sludges, sediments, and soils. Carbon dioxide is generally used for
aqueous solutions, such as process water anci wastewafer. Light
11.2
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Chapter 11
hydrocarbons are recommended for sludges, sediments, and soils.
Supercritical technology can be applied to a large variety of organic con-
taminants, including carbon tetrachloride, chloroform, benzene, naphthalene,
gasoline, vinyl acetate, furfural, organic acids, dichloroe thane, oil and
grease, xylene, toluene, methyl acetate, acetone, alcohols, phenols, aliphatic
and aromatic hydrocarbons, and PCBs.
One vendor reports that its drying/SCE process can be used to remove oil-
soluble organics from soils, sludges, and other wastes as well as to dry aque-
ous mixtures (NETAC 1991). As noted in a US EPA Superfund Innovative
Technology Evaluation (SITE) program report (US EPA 1992a), the process
can be used to treat wastes contaminated with organics, especially wastes
with high water content. The developer claims a new approach for
remediating soils, petroleum K-wastes, spent drilling muds, and hazardous
sludges containing petroleum-based contaminants, such as fuel oils, PCBs,
and polynuclear aromatics (US EPA 1992a). Success is also reported for
removal of dioxins (US EPA 199 Ib; US EPA 1989).
Other vendors have reported success on the bench-, pilot- or full-scale for
removal of pentachlorophenol from activated carbon.
Case histories of the applications of SCE systems are provided in
Chapter 13.
11.1.2 Reliability
Like soil washing, the reliability of an SCE project in attaining the re-
quired treatment standards is dependent upon the relevance and accuracy of
the information on which the system is designed and the experience of the
contractor in operating the system and responding to changing conditions.
Although soil washing has been used extensively in Europe, only a handful
of commercial SCE remediation projects have been carried out. Most of
these projects have been conducted in the United States and some are de-
scribed in Chapter 13.
In general,SCE has only recently been applied in the remediation of con-
taminated soils; therefore, few data on commercial plant operations are avail-
able to evaluate long-term reliability. Most data are from bench-scale, pilot-
scale, or demonstration systems. SITE demonstration reports (US EPA 1990a;
US EPA 1992a) have identified some operating problems, including foaming of
the extraction fluids, gumming-up of process lines, and inteirmittent sticking of
-------
inni' 'in:; i i<
solids to process equipment. Corrective actions have been identified that pre-
sumably will solve such problems In full-scale applications. Amine solvent
extraction is reported to be free of these types of problems.
i , , ,|
Although treatability tests at the bench-scale have shown that SCE is
applicable to a wide range of contaminants, they have also shown that pro-
cess parameters must be optimized for each application. In commercial
appiications,*SCE processes must be able to handle the expected variations
in feed properties found at a given site. Until more data from commercial
applications become available, extensive site-specific treatability testing
should be considered when applying this technology.
11.1.3 Acceptance by Regulators
SCE has been accepted to a limited extent by the US EPA. As of Novem-
ber 1996, SCE had been selected as the technology of choice at five sites.
These sites are: United Creosoting, Texas; Arrowhead Refinery Co., Minne-
sota; Arctic SuiplusrAlaska; Carolina transformer, North Carolina; and
Idaho National Engineering Laboratory, Idaho (US EPA 1996). SCE is pro-
moted by the US EPA's Technology Innovation Office as an available inno-
vative remediation process.
Although there have been few SCE applications to date, the potential
exists for additional use of the technology based on the following factors:
several SCE processes are under, or have completed, evaluation in
.the SITE .demonstration 'programVwhicfi provides independent
verification of the efficiency, operability, and cost of the processes;
MS" ' i 'ซ, "'"Ill ;',lil!l!"" ' "ซ! :. ' nil" TiJIi It"1 "P" ,i j I i^'iliiiintouhfl,. n! ,,:'"n'l,' '" Mi:, If ' I11 i < ซ,., "lป P"1 "J ; Snl1111!"! ,|ป'l' lilV " , ป''ii"!!i' i
commercial SCE processes are already being used to treat petro-
leum refinery and other waste streams, allowing determination of
long-term costs and system reliability;
SCE processes do not require extensive pretreatment of the feed
(other than size reduction) anil can tolerate a wide range of soil
moisture content (from about 5% to 90% moisture); and
"ซ j ' ' _
SCE processes are cost-competitive with other ex-situ technologies
used to treat organic-contaminated soils, sludges, and sediments.
11.4
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Chapter 11
Use of SCE for treatment of contaminated soils, sludges, sediments, and
wastewaters is a new application of a widely-used and well-understood tech-
nology. SCE is used in varied industries such as food, pharmaceutical, fine
chemicals, mining, and minerals processing. The unit operations involved
are also simple and well understood.
SCE has demonstrated a number of advantages in its industrial applica-
tions. It is expected that these advantages will also apply to its use in treat-
ing soils, sludges, sediments, and wastewaters. These advantages include:
demonstrated high removal efficiencies and! low residual values
for a wide range of organic contaminants (PCBs, PAHs, petro-
leum hydrocarbons, pesticides, and dioxins);
demonstrated high concentration factors (up to 10,000:1), result-
ing in greatly-reduced volumes of material requiring additional
treatment; and
concentrated contaminant streams that can potentially be re-
cycled, especially when petroleum hydrocarbons are the soil
contaminant.
Although the unit operations are well proven in other applications, their
use for soil cleanup is still in its infancy. Most of the processes discussed in
this monograph have few full-scale commercial applications. SCE is a de-
veloping treatment technology requiring site-specific application testing and
evaluation.
11.1.4 Acceptance by the Public
To date, the public has not objected to the use of SCE for remediation
projects, and the advantages of the technology appear to be recognized.
However, in some cases, the use of high odor and/or flammable solvents is a
potential problem. The long-term success of these processes depends in part
on the ability of the operators to minimize these potential detrimental effects.
-------
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11.2 Design Basis
11.2J Required Design Information
This section describes the basic information needed to apply SCE tech-
nology with regard to soil physical characteristics, contaminant type and
concentration, approaches to treatment, site conditions, treatment standards,
and schedule.
11.2.1.1 Soil Physical Characteristics
SCE requires excavation of solids or the transfer of pumpable solids to the
point of treatment. Solids produced from such activities are of varying sizes.
Knowledge of the size of the particles to be treated is needed to maximize
extfaction and solid/liquid separation efficiencies. Oversize material (ap-
proximately >5 cm [2 in.] in diameter) is defined as debris and should be
removed prior to treatment via the use of bar or vibratory screens. Alterna-
tively, such material may be crushed or reduced in size using hammer or pug
mills, as appropriate. Size reduction facilitates particle/solvent contact
which increases removal efficiency and reduces the number of extraction
cycles needed to achieve a remediation goal.
Moisture content can affect extfaction efficiency for some SCE technolo-
gies. The degree to which the soil moisture content is a factor in treatment
is directly related to the choice of extraction solvents. Critical Solution
Temperature (CST) and hydrophillic solvents may be used to dewater solids
during the initial extraction stage. When this option is used, provision must
be made for separation of the solvent/water mixture prior to solvent reuse.
This is commonly accomplished using evaporators, distillation columns, or
gravity decanters. Alternatively, the soil may be dried prior to extraction.
Drying may be accomplished through the use of drying beds or by mechani-
cal drying equipment, e.g., vacuum extraction or thermal treatment. When
drying is used, me appropriateness of VOC emission controls must be deter-
minedy Another alternative is toi use hydrophobic solvents at temperatures
above the boiling point of water to dewater the solids by volatilization.
Volatilization requires an additional process to collect and dispose of the
water vapor.
11.6
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Chapter 11
11.2.1.2 Contaminant Type and Concentration
The specific type of contaminant and its concentration can affect the
performance of an SCE system. For example, an SCE system is capable
of removing VOCs from solids; however, other technologies, such as soil
vapor extraction or thermal desorption, may be equally effective and less
expensive. On the other hand, SCE systems can be effective in remov-
ing both SVOCs and VOCs, whereas a soil vapor extraction system
would be unable to remove the SVOC fraction. To date, SCE systems
have been successfully used for removal of SVOCs, PCBs, PAHs, pesti-
cides, and oil and grease. No limit has been identified regarding initial
contaminant concentration. However, it has been shown that the higher
the initial contaminant concentration, the higher the final contaminant
concentration. SCE system operators can compensate for this by in-
creasing the number of extraction cycles, but there does appear to be a
point at which the use of additional extraction cycles is no longer effec-
tive. Consequently, bench-scale treatability studies are recommended to
determine if solvent extraction can meet specified remediation goals.
11.2.1.3 Approaches to Treatment
Hazardous waste sites are not homogeneous; highly contaminated areas,
which are referred to as "hot spots," often exist. Contaminant concentrations
in hot spots are frequently used to specify the upper limits for selection of
remedial technologies. However, excavation, combined with size separation,
tends to redistribute the contaminant load, lowering contaminant concentra-
tions prior to treatment. Consequently, several approaches may be used prior
to implementation of SCE. The first approach is to determine if SCE can
achieve remediation goals based on results of treatability tests conducted on
hot spot soils. The second approach is to determine if excavation and dis-
posal of hot spots is more economical than SCE treatment, reserving such
treatment for the remainder of the site solids. The third approach is to deter-
mine if use of a size separation process could effectively be used to limit the
volume of contaminated soil requiring treatment.
-------
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'11.2.1.4 Site Conditions
Site conditions must allow for operation and maintenance of excava-
tion and screening equipment and dewatering and/or drying of the feed.
In addition, the site should have adequate area for the infrastructure
necessary to support the extraction and solvent recovery plant and for
holding treated solids.
The site conditions that must be considered relative to the treatment plant
itself Include location of the site, layout of the plant and materials staging
area, subsoil conditions at the location of the plant operating pad, location
and specifications of electrical power, location and quality of process and
fire protection water, location of clean solvent storage, and weather condi-
tions that may be expected during remediation.
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11.2.1.5 Treatment Standards
Treatment standards for contaminants of concern are often determined by
conducting a.site-specific riskassessment. In some cases, the risk assess-
:rH|ht''rday':n'o'ryet be completed or is being negotiated with regulators. In
such cases, it is best to base SCE designs on the most stringent potential
standard. Furthermore, solvents used for extraction are not completely re-
moved from the treated solids. Therefore, it is important that treatment stan-
dards be established for any residual solvent.
I
11.2.1.6 Schedule
The schedule under which the work must be performed will establish a
reasonable range of the system throughput rate and thus the size of the
equipment. Project completion dates will be most important and will deter-
mine the shift conditions under which the plant must operate. SCE systems
are flexible in that they are easy to start up and shut down.
r1, ' i ;, !i ..' \ i, "'-,' : i :;l:ii; *:, , ,< '.- -','. i'JI iv
.It. 2.2 Data Collection
Contaminant concentrations in soils, sludges, or sediments are important
for designing an effective SCE system. Such information is usually col-
lected as part of a site investigation and/or a remedial investigation.
-------
Chapter 11
However, such investigations rarely include determinations of particle size,
moisture content, and total organic content (measured as oil and grease), all
of which are useful in designing an effective SCE system. This information
should be gathered as part of a treatability study.
i
11.2.2.1 Treatability Studies
i
Typically, SCE treatability studies are bench-scale. A minimum of two
representative samples of the solids to be treated should be collected. One
sample should represent solids with the highest contaminant concentration
that the SCE unit will be required to treat. The other should represent the
contaminant concentration that the SCE system would most often encounter
during processing. These samples should be analyzed for particle size,
moisture content, oil and grease, and contaminants of concern.
There is no one specific protocol for conducting SCE treatability studies.
Such studies are often conducted by vendors of SCE technologies to deter-
mine if the vendor's process will effectively treat site wastes. Consequently,
data collected under these vendor-specific test conditions may be of little
benefit when considering other SCE technologies. At a minimum, type of
solvent, solvent-to-solids ratio, temperature, pressure, and number of extrac-
tion cycles required to meet remediation goals must be determined. The
ability to separate solvent from solids, and solvent from contaminants should
also be ascertained. Results from these studies should be used to specify
process sequences, unit process sizes, operating parameters, and to develop
implementation cost estimates. A generic approach to conducting SCE treat-
ability studies is provided in the US EPA document, Guide for Conducting
Treatability Studies Under CERCLA Solvent Extraction (US EPA 1992b).
11.2.2.2 Pilot Studies \
A successful treatability study indicates that SCE can achieve cleanup
criteria. Bench-scale treatability studies conducted by technology vendors
may yield sufficient information to pursue immediate implementation.
However, in some cases, it is reasonable to conduct a pilot test in the field
using all unit operations that are intended for full-scale operation. Pilot
studies are used to confirm treatment effectiveness and to identify potential
implementation or process problems that may not be evident during bench-
scale testing.
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Pilot-scale studies for SCE systems vary, and the protocol for such studies
is established on a site-specific basiฃ SGE^rocesses have been piloted in a
number of cases with no more than 45 kg (100 Ib) of solids per batch with a
minimum of three batch runs. Other SCE processes have been pilot tested
using several tons of solids. Such studies seldom require more than a month
of actual field work after securing; the appropriate permits and preparing the
site. Results from the gijpt test ^should1 be used to verify the selection of
process sequences, unit process sizes, arid operating parameters and to better
estimate full-scale costs.
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77.3 Design and Equipment Selection
SCE is based on unit operations from trie chemical process and hy-
drometaUurgical industries. Accordingly, much of the equipment is
standard and ^of^the-shelf." However, complete systems cannot be
purchased anฅmusCtherefore, be designed and assembled by
remediation companies. Designs vary widely from vendor to vendor,
and different process configurations (and solvents) are sometimes em-
ployed for different projects by an individual vendor.
Design procedures are essentially the same as for soil washing and in-
clude the following (in order of implementation):
> sizing of equipment based^on the desired throughput rate,
development of mass and energy balances,
development of a process-flow diagram, and
development of piping and instrumentation diagrams.
Many, if not all, of the design documents listed above must be included in
the application for an operating permit or pennit equivalent.
11.10
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Chapter 11
77.4 Process Modification
An ideal matrix for application of SCE would be a dry sandy soil con-
taminated with <10,000 mg/kg SVOC. Contaminant concentrations above
this level require numerous extraction cycles to achieve stringent cleanup
goals. As the number of needed extraction cycles increases, so does the cost
of treatment. Consequently, excavation and removal of contaminant hot
spots for off-site disposal, or homogenization with site solids of low initial
contaminant concentration should be considered prior to initiation of reme-
dial activities.
Solids with high moisture contents (>30%) can be adequately treated by
many SCE systems. However, dilution of hydrophillic solvents by the mois-
ture, or the additional energy input (due to increased mixing requirements or
thermal energy required to volatilize the moisture) to systems employing
hydrophobic solvents will result in reduced removal efficiencies, and/or the
need for additional extraction cycles to meet a specific cleanup goal. The
use of drying beds, mechanical, and/or thermal driers should be considered
as potential process modifications for high moisture content solids.
SCE processes are a collection of unit processes thait are sized to work in
concert. Many commercially-available systems operate as batch processes
with the extraction vessel(s) serving as the single solids handling device
during processing. Such designs minimize problems often encountered
during solids handling and allow the use of common centrifugal or positive
displacement pumps for the movement of solvent streams during processing.
A comprehensive treatability study, as discussed in Section 11.2.2.1, can
alert the remedial design professional to potential problems that may be
encountered in the field.
The effectiveness of certain solvents in mobilizing organic contaminants
can be pH dependent. For example, certain organic amine solvents remain
in an ionized form at neutral pH. This limits the ability of the solvent to
mobilize organic contaminants. At elevated pHs (>10 s.u.) these solvents are
in an un-ionized form which increases their ability to mobilize organic con-
taminants. Consequently, addition of caustic just prior to initiating extrac-
tion is needed to maximize the effectiveness of such solvents.
-------
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Design Development
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The use of hydrophillic solvents to remove organic contaminants also
results in removal of any water in the matrix. The treated solids are, there-
fore, dry. Removal of such solids from process equipment without the addi-
tion of moisture can produce fugitive dust emissions which may collect on
process equipment or present a safety hazard. Such problems can be re-
duced or eliminated by adding water or steam to the treated solids just prior
to discharge.
11.4.1 Soil Matrix Characteristics
SCE can be used to remove VOCs from most solids, but separation of
VOCs from solvents may prove difficult. As noted earlier, solvents typically
recoveBdby employing"evaporation or distillation systems. SCE solvents
have relatively low boiling points, which minimizes energy requirements and
results in excellent separation of the solvent and high-boiling point organic
contaminants. However, many yqCs have boiling points at or near those of
many SCE solvents that may be used Consequently, the VOCs must be
separated from extraction solvents using fractional distillation techniques.
Well-designed treatability tests should be used to determine if fractional
distillation or some other method of solvent recovery may be required.
I
11.4.2 Physical Conditions
Staging of untreated solids, screening equipment, process equipment,
treated solids, solvent storage, and fire protection equipment must be
planned well in advance of mobilization. Additionally, the planning should
account for the proximity of such operations to existing superstructures,
utilities, and sensitive populationsT this will ensure that operations are con-
ducted in an orderly and timely fashion.
7 7.5 Pretreatment Processes
i PI
11.5.1 Debris and Vegetation
Pretreatment requirements vary depending on the individual site. How-
ever, initial feed preparation is generally the same and consists of removal of
11.12
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Chapter 11
trees, stumps, and other vegetative matter. The soil must be excavated, and
debris and boulders must be either removed or size-reduced. High-pressure
water sprays are sometimes employed to clean the debris and boulders be-
fore disposal.
11.5.2 Feed Preparation
Feed preparation is also process-dependent. Typical operations include
the use of shredders and screens to obtain feed with maximum particle sizes
ranging from about 6 mm (0.25 in.) to about 7.6 cm (3 in.). Note that the
mechanical agitation employed by most processes will result in additional
size reduction.
In some cases, water is added to produce a pumpable slurry. For one
process, water is removed from the feedstock via mechanical dewatering
and/or evaporation.
Another process employs premixing of the feed with the solvent as a pre-
treatment step when contaminant concentrations are high (>3,000 mg/L)(Cash
1992). Premixing effects intimate contact between the solids particles and the
solvent, thereby reducing the overall time required for extraction.
11.6 Posttreatment Processes
SCE processes produce treated solids, water and air emissions, and con-
centrated contaminant extract. Samples of treated solids must be analyzed to
determine if the contaminants of concern have been suf ficiently removed to
meet cleanup criteria. If they do not, provisions must be made for re-treat-
ment or off-site disposal.
Water generated from solvent recovery processes must also be tested for
contaminants of concern prior to disposal in a Publicly Owned Treatment
Works (POTW). Alternatively, wastewater treatment processes may need to
be designed for eliminating contaminants of concern prior to discharge.
Air emissions are minimal from SCE processes. Most emissions are from
process vents used to ensure that excessive pressure will not build up within
the system. Such vents, should be routed to a condenser and/or activated
carbon filters prior to beine discharged to the atmosphere.
-------
I"
Design Development
Contaminant extract is the product of the solvent recovery or purification
system^ All soivent-extractable materialsTare concentrated in this fraction.
Therefore, this material is normally disposed by off-site incineration. Other
options mcludedehalo^^and disposal in a per-
mitted landfill. If the concentrate is not considered a hazardous waste, it
may be recycled.
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7 7.7 Telemetry, Process Control, and Data
Acquisition ' " ' "
The information provided on telemetry, process control, and data acquisi-
tion in the previous soil washing (Section 3.7) also applies to SCE. A spe-
cific process control system used by one SCE technology vendor is de-
scribed below.
1 ' i"1 , , "iM1 n, IF I, ' +, '' ILiill ' ' I I1 ,'!,"! ,,ซ ,,ii| iv i1 ' '': r ,i ' i',', " , ' i' || ,;rป!,ii!,,i!j v ,,| nn,h n ,
This instrumentation control system provides automatic control of the
system and minimizes the requirements for operator attention. All control
functions operate in a fail-safe mode, going to a fail-safe and re-startable
mode upon loss of power. Redundant measurement functions are provided
where needed to ensure safe operation. Additional controls provide equip-
ment protection, indicate:'operating 'parameters','and' initiate alarms in case of
abnormal conditions or malfunctions.
' fodicatqrs," controllers^ anil associated i equipment "are displayed" on and
controlled from a'display and keyboard at the operator interface located near
the solvent extraction system. This equipment permits an operator to super-
vise operation of the entire system, determine the location and type of any
malfunction, and initiate corrective action. Based on final design review
with the client, the local control panel may require installation in a pressur-
ized control cubicle to meet electrical codes.
The overall control system consists of several programmable logic con-
trollers (PLCs), connected to a CRT and an operator's keyboard, which
serves as the operator's interface. A local panel associated with the field
equipment (extractor) requiring local operator attention is linked to the cen-
tral operator display on the control panel to provide the operator information
on field activities. The PLCs are programmed for all discrete and analog
11.14
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Chapter 11
control with software running on an IBM-conipatible computer. The display
panel is programmed as the main computer interface with a supplemental
IBM-compatible keyboard. A data highway connection to the main control
room is provided. Alarms and process summaries are logged and printed in
the main control room.
Two PLC systems are incorporated into the control: design. One PLC
(with redundant backup) is dedicated to control and operation of the extrac-
tor/dryer sequence. Complete isolation of all control logic for the extractor
sequence from other plant control functions ensures safe operation of this
critical process equipment. The final control logic established for the extrac-
tors is permanently burned into read-only-memory, arid on-line logic
changes are impossible. The other PLC controls the remainder of the pro-
cessing equipment and the main operator control interface in the control
room. A noninterruptible power supply is provided for the PLC and operator
interface equipment to permit monitoring and orderly shutdown of the facil-
ity upon loss of electrical power. Communication between equipment skids
and the main control PLC system is via fiber optic cable to ensure the high-
est possible protection from electrical noise and to prevent erratic control
system operation.
All control valves are pneumatically actuated with a spring-return fail-
safe. The combination of pneumatically-operated valves (with several min-
utes of air supply) and battery backup for the control system allows the sys-
tem to shut down the process equipment in an orderly fashion if power fail-
ure occurs. '
Electronic transmitters signal the control room operator with continuous
information concerning process parameters, such as temperature and flow.
Local-only indication of process variables are generally limited to pump
discharge pressures, seal water flow, and similar variables that are typically
of interest to the field operator.
77.5 Safety Requirements
There are numerous safety and health issues that must be addressed prior
to implementation of remedial activities at hazardous waste sites. In addi-
tion to safety requirements applicable to typical waste site activities and
-------
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operation of process equipment (see Section 3.8), two other issues must be
addressed when considering use of SCE processes: (1) working with flam-
mable and thereby potentially hazardous solvents and (2) handling concen-
trated organic wastes.
All SCE processes use flammable organic extraction fluids that present
potential fire and explosion hazards. The flammability of these extraction
fluids varies. Low-molecular-weight hydrocarbons under pressure present
the greatest potential risk of explosion. However, numerous other extraction
fluids are volatile or are considered highly volatile with the potential to pro-
duce explosive vapors. To minimize these risks, all solvent process tanks
must be grounded, and nonsparking pumps and motors (typically pneumatic)
must be used in and around process equipment. Additionally, Chapter 5 of
the National Fire Protection Association (NFPA) standard requires that a
restricted access zone must extend from the extraction plant to a 15-m (50-ft)
radius around the extraction plant, and a control zone must extend from the
15-m (50-ft) line to a radius of 30 m (100 ft)(NFPA 1990). This requirement
may make it difficult to site an SCE system at some locations.
Still bottoms from solvent recycle/recovery systems yield highly-concen-
trated waste streams. These wastes include all solvent-soluble substances
that have boiling points greater than the extraction solvent. Consequently,
the contaminant(s) of concern will be present along with numerous other
organic compounds. This waste stream remains in a relatively mobile state
as it is removed from the process. Due to the concentrated nature of the
waste, individuals who handle this material should wear double layers of
chemical-resistant personal protective equipment for splash protection. Fur-
thermore, secondary containment of vessels holding extract is recommended.
77.9 Specifications Development
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The specifications development considerations presented and discussed in
Section 3.9 for soil washing, including the benefits of "simultaneous engi-
neering" also apply to SCE.
11.16
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Chapter 11
11.10 Cost Data
= - !
Cost estimates for application of SCE treatment systems at hazardous
waste sites vary widely due to site-specific considerations. Some of these
considerations are related to the material to be treated, such as total quantity,
contaminant concentrations, total extractable organic content, moisture con-
tent, and particle-size distribution. Other factors are related to physical con-
straints associated with the site, such as availability of an area for setup of
process equipment, materials staging, and utilities; fire protection; and ac-
cessibility. Each of these variables can affect overall project costs. For ex-
ample, the cost per unit volume treated decreases with an increase in the
total volume of material to be treated. This is due primarily to fixed-cost
items, such as mobilization, site preparation, regulatory compliance require-
ments, and demobilization, associated with process operations. These costs
are incurred regardless of the volume of waste to be treated at a given site.
An economic model developed by the US EPA's SITE program (Evans
1990) categorizes operating costs for SCE remediation technologies into the
following 12 elements:
site preparation,
permitting and regulatory requirements,
startup,
equipment, |
labor,
consumables and supplies,
utilities,
effluent treatment and disposal,
residual and waste shipping and handling,
analytical services,
maintenance and modifications, and
demobilization.
-------
Ill
Based on this model and estimates solicited from technology vendors,
SCE unit costs range from $110 to $5767tonne ($100 to $523/ton)(see fable
11.2). The values presented in Table 11.2 are estimates and can vary sub-
stantially for the abovei listefi reisons. The quoted unit costs include the cost
of disposal and destruction or treatment of all residue, analyses associated
with system operations (except for the Carver-Greenfield process), and mo-
bilization and demobilization.
Table 11.2
Cost Comparison
Quoted Costs
$/tonne
Process ($/ton)*
B.E.S.T.
CF
Systems
Carver-
Greenfield
TKRG'"
165 (150)
110-550
(lob-Sob)
129-576
(117-523)
187-330
(170-300)
Wet vs.
Dry Site Quantity Disposal/
Pricing Preparation tonne Destruction
Basis Included (ton) of Residues Analytical
Wet No > 18,000 Yes Varies
Mob/
Demob*
'" Yes"
Profit
Included
Yes
; ;. , -in '::::::, (> 20,000)
Wet Yes > 57,000 Yes Yes
Yes
Unknown
(> 63,000)
Wet Yes 21,000
Yes No
Yes
Yes
(23,000)
Wet Yes 675
(750)
Yes Varies
Yes
Yes
Costs are estimates only and are expected to be site-specific.
"Mob = mobilization, damob = demobilization
"Terra-Kleen Response Group, Inc.
Source": ""Donnelly et a'l. 1995' (modified); (JS EPA i"997
The US EPA has published detailed cost estimates for the CF Systems
process (US EPA l9^0a)"'ahdlhe"Carver-(j^nfield1'prbcess (US EPA
1992d). These estimates include technology-specific costs and a breakdown
of site-specific costs. In estimating costs for the CF Systems process, the US
EPA postulated the following scenarios:
a base case toeating 800,000 tonne (880,000 ton) of sediments
contaminated with PCBs in concentrations of 580 mg/L at 450
tonne/day (500 ton/day) over a 11.3-year period;
11.18
-------
Chapter 11
a hot-spot case treating 57,000 tonne (63,000 ton) of sediments
contaminated with PCBs in concentrations of 10,000 mg/L at 90
tonne/day (100 ton/day) over a 1-year period; and
analytical costs of $500/day in both of the above cases.
The estimated cost for the base case was $ 163 ฑ 20% per tonne ($148 ฑ
20% per ton) of raw feed, including excavation and pre- and posttreatment
costs, but excluding final contaminant destruction costs. Excavation and
pre- and posttreatment costs were estimated to be 41% of the total costs.
The estimated cost for the hot-spot case was $492, -30% + 50%, per
tonne ($447, -30% + 50%, per ton) of raw feed. Excavation and pre-
and posttreatment costs were estimated to be 3296 of the total costs (US
EPA 1990b).
US EPA also estimated the cost for the Carver-Greenfield process
assuming treatment of 21,000 tonne (23,000 ton) of drilling mud con-
taminated with petroleum wastes. The total cost estimate was $576/wet
tonne ($523/wet ton), with $243/tonne ($22 I/ton) allocated to technol-
ogy costs. Site costs were estimated to be $333/l:onne ($302/ton), in-
cluding $264/tonne ($240/ton) for incineration of contaminated residu-
als. The estimate excluded regulatory, permitting, and analytical costs
because of their variability. Also excluded were effluent treatment and
disposal costs. Rather than assume a cost for incineration, the vendor
assumed that the process would separate indigenous oil, which would be
sold to a refinery for $26/tonne ($24/ton), resulting in an overall cost of
$285/tonne ($259/ton)(US EPA 1992e).
11. J J Design Validation
The design validation concepts presented and discussed in Section 3.11
for soil washing also apply to SCE.
-------
Ill III (
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7 7.72 Regulatory Permits
As noted in Section 3.12 regarding permitting of soil washing applica-
tions, a complete review of pertinent environmental regulations must be
conducted early in the remediation process, and appropriate federal, state,
arid local permits must be secured prior to initiating site work. Processes
and process residuals unique to SCE systems must be addressed during the
permit process. These include use of flammable solvents, volatile emissions,
and handling of concentrated, waste streams.
.''..; "'.'':;- I'!-' '; ":;!": '":"*ป'"'Si ,ป:< "5* ;. "i ' " I"'11'''"1'-'! , i;" '*ป.'' ' w i,' '< "-H.s. lit1' ':
7 7.73 Performance Measures
SCE is a separation technology. It is employed to significantly reduce the
volume of waste that must be further treated and must produce a treated
residue that meets the requirements of the Record of Decision (ROD) or
other performance requkements. Thus, all or the associated performance
measurement considerations presented in Section 3.13 for soil washing
apply to SCE.
, IIPI II! B!l:i
i
(111 II II
77.74 Design Checklist
ii i in i ll
The following is a design checklist for SCE.
1. Waste Characterization
Concentrations of contaminants of concern
Particle-size distribution
Moisture content
,1
Concentration of the total solvent soluble fraction
2. Site Conditions
Site access
' , .: ', ,i. j, i" ' ' .";!
Facility layout
11.20
Jtivfljl
-------
Chapter 11
Excavation/staging plan
Pad and containment requirements
Utilities access
Building requirements
Support facilities (offices, decontamination facilities)
Hot spot locations
3. Treatment Standards
Contaminants of concern
Cleanup goals
Disposition of "clean" material
4. Treatability Study Information
Soil matrix/contaminant evaluation
Conceptual process-flow diagram
Conceptual engineering
Cost estimate
5. Schedule
Site preparation
Process equipment mobilization
Waste processing
Demobilization
-------
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-------
Chapter 12
IMPLEMENTATION AND OPERATION
72.7 Implementation
The procurement and contracting considerations presented and discussed
for soil washing apply equally to SCE. One SCE vendor offers to sell or
lease units for its solvent-based process or to provide treatment services for a
specified fee.
72.2 Start-up Procedures
Startup of a SCE system follows essentially the same procedures as those
for startup of soil washing systems. These procedures include hydrostatic
tests of the process tanks and plumbing followed by process runs using clean
soils. At that time, a complete check of the operating equipment for leaks
and system grounding is conducted. For a detailed discussion of start-up
procedures refer to Section 4.2 on soil washing.
72.3 Operations Practices
The considerations presented in Section 4.3 for soil washing generally
apply to SCE. However, SCE uniformly yields essentially 100% of the start-
ing mass as cleaned product, whereas soil washing, sometimes produces a
contaminated fines stream containing an appreciable amount of the starting
12.1
-------
'ii'T V I'lWiWl i1 L 'V'iifiiiiir'i' ":;"!. '" l'!llll!|l|iLli;i|fl"|1f!: ป"Bii i?'1'1! "I":',*! 'W1".'"'; 'lill1'1,,!1!.'1'' ''I^iff' fill
JBI'iiii"ป!,; ,;i, - :,i, i ,. ,1 ' irfi ... , ' ;1,. -; t " "l."i:~ , ^ , : . ;' s
Implementation and Operation
mass Hence, the major performance indicator for SCE is meeting the treat-
ment standard for the entire mass of feed soil or sludge.
\-\t-- 'ii:,-: " :,. "?, ' \. : v .. i, "'.',..> '-.> '. .ป M.?.-< .'isf"11.,*! ซ" fi:*1,,11-1"*' r ;:! : ,. !<;'. t 'Mat 'ป':ป
72.4 Operations Monitoring
\
Operations monitoring is conducted to ensure that the process oper-
ates efficiently, consistently, and safely. The specific requirements for
such monitoring are dependent upon the design of the remedial action as
well as the specific SCE process ernployed. Section 4.4 on soil washing
provides a general perspective of the types of operations monitoring that
would be typical for remedial processes. The parameters to be moni-
tored for SCE systems include:
1. Screening
Loading (mass/volume)
2. Extraction
Solvent addition (mass/volume)
, , ' ; ' , ,,T : ;; : i ; '
Duration of extraction cycle
Mixer speed
' Temperature
i
Pressure
3. Phase Separation
Duration of phase separation
Visual inspection of separation effectiveness
Concentration of contaminants in the solvent
i
4. Solvent Recovery System
Temperature
: |
Pressure
j
Condenser temperature
;" ' ,' '' -:
' - .- ,.- : ; ' 12.2
-------
Chapter 12
5. Treated Solids j
Appearance
Concentration of contaminants
72.5 Quality Assurance and Quality Control
The Quality Assurance and Quality Controls in Section 4.5 for soil wash-
ing also apply to SCE.
12.3
-------
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ikllllH^^^^^^^^^^^^ illdiili iJllJIll!' IllhliiiiiiliiJ
-------
Chapter 13
CASE HISTORIES
This chapter presents four Solvent/Chemical Extraction (SCE) cases.
Each of these cases are reprinted verbatim (other than minor edits to con-
form to the monograph outline) from previously published works.
In the first case, the US EPA's Superfund Innovative Technology Evalua-
tion (SITE) Program evaluated a pilot-scale solvent extraction process devel-
oped by the Terra-Kleen Response Group (TKRG). This process uses a
proprietary solvent, or mixture of solvents, to extract organic contaminants
from solids. A pilot-scale evaluation was conducted at Naval Air Station
North Island (NASNI), near San Diego, California, on soils which were
contaminated with polychlorinated biphenyhi (PCBs) and other organic sub-
stances. 4.5 tonne (5 ton) of soil with an average PCB concentration of 144
mg/kg were excavated, homogenized, and equally distributed to five extrac-
tion vessels. Eleven extraction cycles were used to produce a treated soil
with an average PCB concentration of 1.71 mg/kg on a dry weight basis
(98.8% removed). Oil and Grease (O&G) removal efficiencies were found
to be 65.9%. This low O&G removal efficiency was attributed to solvent/
solute relationships. Initial concentrations of hexachloro-dibenzofuran
(HxCDF) in soils averaged 0.067 |0g/kg. Following solvent extraction, no
HxCDFs were detected (<0.117 Jig/kg) in soil samples. A full-scale solvent
extraction system was operated at a site in Stockton, California. Pesticides
were extracted from 454 tonne (500 ton) of contaminated soil using 19 ex-
tractors, each 15.3 m3 (20 yd3) in volume. Three extraction cycles produced
solids with <0.093 mg/kg residual pesticide (<99% removed). These results
demonstrate that the TKRG's solvent extraction process is effective in re-
moving organic contaminants from soils.
The case was developed by Mark C. Meckes, Scott W. Engle, and Bill
Kosco, and reprinted with permission from the Journal of the Air and Waste
Management Association, Volume 46, Number 10, October 1996.
13.1
-------
Case Histories
II, 'Bis:. ;, ' ' It
' it:t!
' ..... "
IH t I.
Illfll',,!,:,!> Vnl >:i:l", ^' , ' :" r'.effl!' FW.
' .11 ........ .'' .r , "', , ,., , I,, ' 'ป ......... ,| ..... ;i||, IM 'i'iiป " IK'Hiiiiiili i 1. 1ป .' ''I'M .\JUhlplL. ,i Mr II. lil ...... V ill1 ''!'!,' ..... I ..Iff,, '" ..'.m1!!:,, ,' iiLi "' - . "" ป '" '. ..... Jiii ..... i ...... .'"|'^~N.I ...... B,,,.ir
This STD case was developed by Joseph Tillman, Lauren Drees, and Eric
Saylor as a part of US EPA's START and SITE programs in Cincinnati, Ohio
to announce key findings of a solvent extraction treatability study that is
fully documented in a separate report of the same title.
' ..... ' ^ _ _ ' ' ' ...... 'p The'"third case describjeV the' p^^ a" combination of
dehydration and solvent extraction treatment technologies, this has wide
applicability for separating hydrocarbon solvent-soluble hazardous organic
contaminants (indigenous oil) from sludges, soils and industrial wastes. As a
result of this treatment, the products from a Biotherm Process facility are:
, ;;, .,: ; , , ,, . ..... ' ' ,.. , , ; ' : ...... ,13.2
-------
Chapter 13
(1) Clean, dry solids which meet U.S. Environmental Protection
Agency (US EPA) Resource Conservation and Recovery Act
(RCRA) Best Demonstrated Available Technology (BDAT)
and/or Toxicity Characteristic Leaching Procedure (TCLP)[40
CFR, Part 261] regulations for hydrocarbons (typically less
than 0.2% [by weight]) and are suitable for disposal in non-
hazardous landfills;
(2) Water which is virtually free of solids, indigenous oil, and sol-
vent and is treatable in an industrial or Publicly Owned Treat-
ment Works (POTW) wastewater treatment facility;
(3) Extracted indigenous oil containing contaminants which may be
recycled/reused for credit or disposed of at less cost man the
original waste feed.
A successful demonstration of the Biothenn Process on spent oily drilling
fluids was part of the US EPA Superfund Innovative Technology Evaluation
(SITE) Program. In this paper the use of the Biothenn Process for economic
treatment and minimization of hazardous refinery wastes is described, the
SITE program results are reviewed, and the Biothenn Process technology
extension to treatment of other wastes is presented.
The Biotherm Process case was developed by Theodore D, Trowbridge
and Thomas C. Holcombe.
The fourth case is an evaluation of Resources Conservation Company's
(RCC) Basic Extractive Sludge Treatment (B.E.S.T.ฎ) pilot plant. This
evaluation was conducted between July 1 and July 22,1992, during a dem-
onstration by the U.S. Environmental Protection Agency (US EPA), under
the Superfund Innovative Technology Evaluation (SITE) Program. The
demonstration evaluation was conducted in Gary, Indiana; the material
treated was contaminated river bottom sediments collected from two loca-
tions within the Grand Calumet River (GCR). The organic contaminants of
concern were PCBs and PAHs.
This demonstration was part of a cooperative effort. In addition to the US
EPA SITE Program, other agencies included US EPA's Great Lakes National
Program Office (GLNPO); the U.S. Army Corps of Engineers (COE), Chi-
cago District; and US EPA Region V. The GLNPO Assessment and
Remediation of Contaminated Sediments Program through the COE, in
13.3
-------
Case Histories
cooperation with US EPA Region V, arranged for the developer's services
and the location where the demonstration was conducted.
ill lllllill I , fir ,,'",, ' \;il!ji i'."ij i. "" i :(! ;./ i,]:;'1,i1 ii i, ;, [ , -', ],ti,, ;|i;* ; :, v,l/::, 4"; "I. KvW.l " ilV.Wihj.'l IK'ซ!lil|J,ilfi, -X.Mli "IB*":"" ;- V.T t..'.W .j*d|' Jป f
GLNPO leads the efforts to carry out the provisions of Section 118 of the
Clean Water Act (CWA). Under Section 118(c)(3) of the CWA, GLNPO is
responsible for undertaking a five year study and demonstration program of
methods for the;,assessment and remediation of contaminated sediments.
One of the areas of concern for priority consideration is the GCR. TheCOE
(Chicago District) has authorization (Rivers and Harbors Act of 1910) to
maintain harbor channels by periodic dredging. This
%.(, " ... :"1 ilL :''i';;;ciuu^ 1
designated the bottom sediments at various locations as moderately polluted,
heavily polluted or toxic. As a result, materials to be dredged from the Indi-
;\ :P;;; " ' ,'H. aha Harbor and Canal are not suiteble for open-water d^
Michigan. At the present time, an environmentally acceptable disposal facil-
ity for dredged materials from Indiana Harbor does not exist. Consequently,
""'''dredging to maintainadequateinavigaHolildepth's has not been conducted at
I; ill in :.(., n ",, I '-if : ; 11 "it, (i: ;l '' I';";, i."'F" iป''" ป ' '-tซ4>r'r" ' """ """ ' '""" ""'' ' " ' '"": ' "'"' ' "l"'
this harbor since 1972.
"Ill liii.ll 'H!1 " " Ji ป 11
i, m. . :i n
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Cose 7 Site Demonstration of'Terra-
MM' , Jj ,' ; jiiP ,,,i f! ,,i , V ill!,,, f ,!:'!,!!:,!!'.I1 jl,,i "L lit":!!!1,'!' nl1!!".1'1 iillll^lftilf:/!!!* ai!llป !",'f>^, I BIHii!1' ^"' II ' J * ^- !"ป.'
Kleen Response Group's Mobile Solvent
Extraction Process
In 1986 the US EPA Office of Solid Waste and Emergency Response and
the .Office^of Research andpevelppment estabjished the Superfund Innova-
tive Technology'1 Evaluation (SITE) program to promote 'th'e 'd'evelopmenf 'ami
use of innovative technologies to clean up uncontrolled hazardous waste
sites across the country. The SITE Program is composed of four major ele-
ments: the.pempn'sttatib^P^pgram.''^EmergliigTechnologies program,
the Measurement and Monitoring Technologies Program, and the Technol-
ogy Transfer Program (US EPA 1994b). The Demonstration Program is
designed to provide engineering and'cosT2[Iata"'for'sete'cte
-------
Chapter 13
The Terra-Kleen Response Group (TKRG) requested that US EPA's Site
Program evaluate their mobile solvent extraction technology, and was se-
lected for evaluation under the Demonstration Program. This technology is
a batch process system which uses organic solvents to separate contaminants
from soils, sediments, and sludges. Organic contaminants are concentrated
during processing, thus reducing the volume of hazardous wastes for final
disposal. Therefore, this technology is nondestructive.
TKRG's solvent extraction process is transportable and can be configured
to treat both small and large quantities of solids. System components are
often available from local suppliers throughout the United States. This avail-
ability of system components reduces setup time and can reduce the amount
of down time associated with equipment replacement.
The process is designed to use up to 14 different organic solvents or
blends of solvents to extract organic contaminants from solids. The
identity of these solvents is proprietary; however, none of the solvents
used is listed as a hazardous waste according to the U.S. Code of Fed-
eral Regulations (1994). i .
A schematic diagram of the TKRG's solvent extraction system is shown
in Figure 13.1. Processing begins following excavation of contaminated
solids, which are loaded into extraction vessels. The vessels are covered,
and clean solvent at ambient temperature and pressure is pumped into each
one. Organic contaminants in the solids are mobilized by the solvent with-
out the aid of a mixing device. Contaminated, solvent then flows into a clari-
fier, where heavy solids are separated from the solvent by gravity. Clarified
solvent is pumped through a microfilter, which removes fines, and then
through a proprietary solvent purification unit that concentrates the organic
contaminants. Clean solvent, discharged from the purification unit, is stored
in a holding tank for reuse. This sequence of treatment steps, known as an
extraction cycle, is repeated until contaminant concentrations of the solids
within the extraction vessels are reduced to a desired level. At this point, the
extraction vessels and all solvent carrying lines are drained, and the suction
side of a centrifugal blower is connected to each vessel's solvent discharge
line. Much of the solvent retained within a vessel volatilizes as air is rapidly
drawn through it by the blower. Vapors discharged by the blower are passed
through a condenser, where spent solvent is recovered as a liquid that is then
filtered and processed through the purification unit. This recovered solvent
is returned to the solvent storage tank for reuse.
13.5
-------
i ซ =- - -- i iซ! t"'"ป<
_'-'- !? !! ;i:i*r! ซ;35i;Sfc::^ : f
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i i :; ! :s - *i
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E= I _ _ = _ 3 :....;= JS _ i> J iXj _ . r__ 5 . "-^ _
f " = _ . _ ' K i , P -:- '=-.-
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* ' . z := - . * ซ- - "_ .- 'at.
s -L _ ^ __ _^ _ __ - - _ _ ^ :
_- . _ i_ I ,; :. ; -- -r ^ : _ฑfl"^r- - :
F ' i ^ ;: :? ;; ';';^ii ^r
; -" ; i, I !i ; '_ t (ijii IS !;
= J i: - s - I- -=---=*-" -T sk^sff -_ =-^t -^ i . _- -
f " T '!! l'ซ -.i ^ .- 1
: - "- i. "" f "2". ' t ='-. i -^*T, t " " ' " f
i II H ป -! . 'I !: ' - < ill 1 I (ซ,! * f
3 ---'-'-: I : = i =~? = :K i
i i-- ^i -,- s- - - - i- -r =
i :S a , (i : ; ; , ... : ; . ._;; ,, i
5 ; 1!! 1! i i ; ' i " ! ! !iซ';- i
"-"'':-" I I : i ^ :
i MB j,; ' - s , :: -- -. -- ta
p ,a iy a ,) s ( ! Mi, - a
:-.<*..- ' - : ,
Figure 13.1
Simplified Process Schematic Terra-Kleen Solvent Extraction Process
ITon ITon ITon ITon ITbn -,=-._ -.
; , Contaminated Soil Contaminated Soil Contaminated Soil Contaminated Soil Contaminated Soil , g
$P QP $P . ,, ^
TankA TankB TankC TankD
Solvent Extraction Solvent Extraction Solvent Extraction Solvent Extra
and and and and
Biological Treatment Biological Treatment Biological Treatment Biological Tre,
cx> Contaminated
O 3 Solvent < r ' ' ' '
lttlt**l***l*im**m*ppป*ปmmm*m*T-I ,.... iutt It,, . ^- . 1 ^
: VentGas
T
Vapor
^l1?.^?11 * '
Sedimentation
Tank
i,-
i; ...... "j^ Air and solvent vapor
1, ;! . ... <|T)(sz)(g) Sample locations
t! ;
i ___^
% i * f ! * =
TankE :i:-
ction Solvent Extraction 1 *v ' "
and : ,.--; ซ
atment Biologsca! Treatment ; = ~: -.
Contaminated = ;r=, ; ?
i Solvent i IT =-;
.: : m
...............^..... .............. ^
Filtration ! : "" " P
Unit f_ --ft: i 0=
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Purification V Storace : ^'- ^. i
Station ^ , :?^.-' ^
1 1 , ^s ^ ฃ
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.i!1'1!^ h 1m NB^JLilHti , i'1 Ii" u|' 'JHI j; ijji,!,; ,, i,, ,'."' ' i, ' ,, ,1! , j |ni , ' ! . ii;;ilrl" !'ซEW^ , , , I'll1'' ,
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Case Histories
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-------
Chapter 13
Some solvent remains associated with the treated solids following vapor
extraction. Further reduction of this residual solvent is effected through
biodegradation. This is accomplished by addling a mixture of water, nutri-
ents, and microorganisms to the soil in each extraction vessel. The vessels
are allowed to stand until residual solvent concentrations have been reduced
to acceptable levels for land disposal (several days).
Treated solids typically are removed from the vessels by a front-end
loader and returned to the site. Contaminants concentrated by the solvent
purification process are removed and disposed of off-site in accordance with
applicable regulations. Purified solvent may be used for treatment of solids
at other waste sites.
The SITE Demonstration of this technology was conducted during May
1994 in cooperation with the Naval Environmental Leadership Program
(NELP) at Naval Air Station North Island (NASNI) near San Diego, Califor-
nia. TKRG was contracted by NASNI to treat 4.5 tonne (5 ton) of soil con-
taminated with polychlorinated biphenyls (PCBs). The performance of the
TKRG's solvent extraction process was evaluated under the direction of the
SITE project manager in accordance with a mutually agreed-upon quality
assurance project plan. This project was considered a pilot-scale demonstra-
tion of the capabilities of the TKRG's solvent extraction process. The pri-
mary objective of this demonstration was to determine if the process could
achieve a soil cleanup level of <2.0 mg/kg total PCB.
Experimental Methods
NASNI environmental managers used existing site to identify an area on
base where soils were contaminated with >100 mg/kg PCB. A backhoe was
used to excavate 4.5 tonne (5 ton) of PCB-contaminated soil from the area.
This soil was then homogenized, using the front-end loader of the backhoe
for mixing. Five extraction vessels (designated A through E) were filled
with approximately one ton of homogenized soil, and were weighed to deter-
mine the total mass of soil to be treated. A sampling grid was laid out across
the top of each vessel, and a core sampler was used to collect seven samples
from each vessel. The seven samples were composited by vessel such that a
composite sample represented the contents of an individual vessel. These
samples were analyzed for soil moisture content (ASTM 1992) and particle-
size distribution (ASTM 1990) in accordance with American Society for
Testing and Materials (ASTM) methods. PCBis, volatile organic compounds
i
13.7
-------
ilill! 'I' I'll !-,, ! i ' "1" i,, I",,,, . iป, 1! * ill!", f ,' ' "i"' I i'|i,i' ii,, :",, 'I'iBIIII!, iQ, ' i,1" ii'iinni,,. 'i nn ,|,! '"I! ' i , :;i
I""1 "*!' .lii'"1! "Ill 111.1 li ' , '1 ''JjilR '"' .JJIW'Jl li'i ,, Hi"1 , '"1 ,"
:i & :s""!. *, <* : w ';ซ"5 , *"
::'i"11!? "1' Case Histories
IIPVI -.i1"1",:!1 1 :' ' , i.'i"f
VUjlii!;1,! jl'HF ''ill!!!'!:1 ' " "'1,1,114! II
' ill;11!1!,!:11'lili1"!,!,! , 'I'1," 'I! !" "Wli
, , , I I I. ,ซ ''Itt'l'tMiili! >.*."T
(VOCs), semivolatile organic compounds (SVOCs), and oil and grease
(O&G) were analyzed in accordance with US EPA's test methods for evalua-
tion of solid wastes (US EPA 1992g).
Following sample collection^ approximately 380 L (100.4 gal) of clean
solvent were added to each extraction vessel to cover the soil. After approxi-
mately 30 minutes, a drain valve was opened, and the solvent was permitted
to drain by gravity into a clarifier. The total elapsed time for this fill, stand,
and drain regime was approximately four to six hours and defines a single
extraction cycle. Samples of the extraction solvent were periodically col-
lected from the drain lines leading to the clarifier. Results from PCB analy-
sis of these samples were used to determineTif additional extraction cycles
were required to meet the predetermined soil cleanup goal (<2.0 mg/kg
PCB). The clarified solvent was pumped through a 5 micron bag filter and
then through TKRG's proprietary solvent purification station. Samples of
the purified solvent were collected periodically and analyzed for PCBs to
determine if the purification system was effectively removing contaminants
from the solvent. Purified solvent was pumped into a storage tank and held
there until it was''reusecl for subsequent extraction cycles.
When the solvent in all of the extraction vessels had finished draining, the
valves to the drain lines were closed, and a second" extraction cycle was initi-
ated. The extraction "cyclesfwere continued until the measured concentration
of PCBs in the drained solvent was <2".0 mg/L. Vapor extraction was then
employed to 'furflher recover solvent from the solids. The suction side of a
centrifugal blower was connected to the drain lines of each extraction vessel
and was operated continuously for three days. Following this treatment,
biological degradation of the remaining solvent was encouraged by spraying
a mixture of water, nutrients, and microorganisms onto the contents of each
extraction vessel,arid seven core samples of the solids were collected,
composited, arid analyzed for contaminants as described above.
Results
The characteristics of the soils obtained from each extraction vessel prior
to treatment are shown in Table 13.1. The untreated soil was a dry sand with
an average moisture content of 0.83%; 93.6% of tide solids was retained on a
0.075 mm screen. Polynuclear aromatic hydrocarbons (PAHs),
hexachlorodibenzofurans (HxCDFs), and pentachloro dibenzofurans
(PeCDFs) were identified, but only at low concentrations (total PAHs <3.4
-------
Chapter 13
Table 13.1
Physical and Chemical Characteristics of Untreated Soils
Extraction Vessel
Analyte
Particle Size (% > 0.075 ram)
Moisture Content (%)
Total PAHs2 (mg/kg*)
Total HxCDF3 (mg/kg*)
Total PeCDP* (mg/kg*)
Total PCS5 (mg/kg*)
Oil and Grease (mg/kg*)
A
92.7
0.79
2.10
0.659
< 0.409
130
747
B
93.4
0.79
223
0.629
0.144
140
720
C
93.4
0.79
338
0.647
< 0.343
134
707
D
935
0.80
155
0.848
0.162
147
767
E
95.0
0.99
154
0.704
0.218
170
860
Mean
93.6
0.83
224
0.697
< 0.255
144
760
SD1
0.85
0.09
0.69
0.089
-
15.7
605
'Standard Deviation
2Polynuclear Aromatic Hydrocarbons
"Hexachlorodibenzofuran
4Pentachlorodibenzofuran
5Polychlorlnated biphenyl
Dry weight
mg/kg; total HxCDFs <0.85 Hg/kg; total PeCDFs <0.7 mg/kg in the un-
treated soils. Other analyses showed the average O&G concentration to be
760 mg/kg and the average total PCB concentration to be 144 mg/kg. The
only PCB mixture identified matched Aroclor 1260 chromatographs.
Eleven extraction cycles were completed over seven days for each of the
five 1 tonne (1 ton) batches of contaminated soil. Solvent discharged from
one of the five extractors (A) was sampled and analyzed for PCBs after the
first, second, fifth, and eleventh extraction cycles. Results from these analy-
ses are shown in Figure 13.2. To limit the number of analyses, no attempt
was made to sample solvent discharged from the other four extractors. The
highest concentration of PCBs in the discharge solvent (61 mg/L) was ob-
served following the first extraction cycle. This was expected, since a high
initial concentration gradient existed between the solvent-soluble soil con-
taminants and the clean solvent. After completion of the first extraction
cycle, the solvent-soluble contaminant concentrations in the soil were re-
duced to a level below the initial contaminant concentration, thus reducing
the concentration gradient between the remaining solvent-soluble
13.9
-------
PliPiii- /Hi!1"" I * ป'., * , I!!!
IIP '
(a
Case Histories
I:!1 Oi?: , ill!":! !, -tป
.[ ';,''' /> i L s
ilillii 'If!.!' !ป'
!!;' hum! i|' "in i"
li!:v":< -T"' :ป!:.!ป;
J l!1';.,,!1' . "<,'': si:""!'!!!!'*" fell
ii," 'iltili, iiiiP!ll:iil!!!
ill 111 I'll) I
i LI
111'"!1" i
i S'i1'1!"
":'' '!!"' <
,,' I: i^11 ? 11?" **?!!'''''':i:.!'?:;":" "i' i-1'; '* Mf?f'' *'*' '*"'
contaminants and the solvent during the'nexrextractfon cycle. ^-^Q^CQ of
this is seen as the reduced solvent PCB concentration (14 mg/L) following
the second extraction cycle. This same phenomenon is believed to be re-
sponsible for the observed reduction in solvent PCB concentrations follow-
ing the fifth p.,4 mg/L) and efevehtn" (1 9 mg/L) extraction cycles.
After vacuum extraction was completed, the covers were removed from
the extraction vessels and a proprietary mixture of water, microorganisms,
C , , ;i;' ' j"|,ni!'. 'ij 'i!!|*j hiJJJ ' ',,, S'lSifi |. ,' ' iiiiป;ซ; J J11. jt ','':*''^f "'illfi1"111,' Ililjiyii.].]!1'1 .nm'UBm H'lliiiiWil.'lll, IIIIIIH^^^^^^ ซ' IB1' '''IK''*!:.'!^!!''1''!^!""'''*' ."ii,i,i nipiii"^ >"i' , *ป - ^^ jr '
knd nutrients was sprayed over the exposed soil surfaces. Soil samples were
I"!,.,, ni!||,,; , 'f'llSll! ' (I!' I"1''f" Bull H1 !r '.'' "In! iiiETMiniiiihi Sfm ป,,iiiii , .nr !, ซi,ii,ปiinซ ii * ,
-------
Chapter 13
O&G, PAHs, PCB, and, HxCDF in untreated soils were above method detec-
tion limits. Only the O&G and PCB concentrations in the treated soils were
found to exceed the method detection limits for these analytes. Figure 13.3
graphically compares the concentrations of O&G in soils before and after treat-
ment. The average concentration of O&G in the treated solids from all five
extractors was 258 mg/kg, yielding an average removal efficiency of 65.9%.
However, some variation in individual extractor performance is evident. For
example, removal efficiencies O&G ranged from a low of 58.5% for extraction
Tank A, to a high of 79.3% for extraction Tank D. Some of the observed varia-
tion can be attributed to sampling and analytical activities.
Figure 13.3
Oil and Grease Concentrations in Soil Before and After Extraction
1,000
soo -
BCD
Extraction Vessel
I Treated
I Untreated
Data variability is common to monitoring activities, regardless of the
matrix or technology under observation. To determine if the observed varia-
tion in O&G results was reasonable, the treated soil O&G concentrations
13.11
-------
iiiniiiiiir ' :>,'*, in. it i f
'S H
1 ......... i
f 'i
..... if:
Case Histories
i' f
II, Hill1 "i'
ซlll Kill J
ilrf iii11: '' i Hiii:
from each extraction were compared to the average O&G concentrations
from all five extractors, plus or minus two standard deviations (258 ฑ 124
m|/kg). Results from mis comparison show that all treated soil O&G con-
centrations were within two standard deviations of the average value. This
indicates that the observed variation between extraction tanks in product
O&G concentrations was within control standards for this investigation.
Regardless, the O&G concentration of the product solids from all extraction
tanks was shown to be <310 mg/kg.
B i;. iiv.i1;; Y " .i;111",111;.!,"! in: r-fjti .'...'> I i ill I n I J i iiiiiii mi j.'.xw ' ; '.Jt J j '' "
An earlier study (Meckes et al. 1993) using an alternate solvent extraction
pfoc'eSs at an Indiana waste site described an average O&G removal effi-
ciencyof 98.29S following treatment of one contaminated sediment sample.
Sediment treated by that system had much higher initial O&G concentra-
tions (mean = 7,580 mg/kg) than did the untreated soils used for this investi-
gation (mean = 760 mg/kg). The average O&G concentration following
treatment of sediments at the Indiana test site was found to be 140 mg/kg.
This is less than half of the average O&G concentration observed in soil
samples following treatment by the TKRG's process, and likely reflects the
differencein.toe.makeup of the O&G fractions between waste sites. No
direct companson waTmaHe' 'taetween'me two solvent extraction systems on
split samples from a single source of contaminated solids. Therefore, based
upon the above results, it is impossible to determine if one of the two sys-
tems could more effectively extract O&G from a given source of contami-
nated solids.
. - .' '. .- " '" ."ป.: ' , | - " " " - ' '- <
. PCB Removal ] j t_
PCB removal was consistently highiwith an average removal efficiency of
98.8%; concentrations of PCBs in treated soils averaged 1.71 mg/kg. Ana-
lytical results of the treated soil samples from all five extractors confirmed
that the treatment objective to produce soils with a total PCB concentra-
tion of <2.0 mg/kg was achieved (Figure 13.4). Furthermore, it was de-
termined that the average PCB concentration in the treated soil (1.71 mg/kg)
was significantly less than 2.0 mg/kg (significance level a - 0.05). The
observed range of PCB concentrations (O5 to 1.54 mg/kg) shows that little
variation existed between the treated soil samples obtained from individual
extraction vessels. As was noted above, some of th'e observed variation can
be attributed to sampling and analytical activities.
13.12
-------
Chapter 13
Figure 13.4
PCB Concentrations in Soil Before and After Extraction
B
200
150
100
50
170
130
134
1.701
1.541
1.691
BCD
Extraction Vessel
I Treated
I Untreated
To determine if the observed variation in PCB results was reasonable, the
PCB concentrations for the treated soil from each extractor were compared
to the average PCB concentration for all five extractors, plus or minus two
standard deviations (1.71 ฑ 0.22 mg/kg). Results from this comparison show
that all treated-soil PCB concentrations were within two standard deviations
of the average value. This indicates that the observed variation between
extraction tanks in product PCB concentrations was within control standards
for this investigation, and confirms the effectiveness of the process in consis-
tently meeting the specified soilcleanup goal.
i
HxCDF Removal
Concentrations of HxCDFs in untreated soil samples were all below 1.0
Mg/kg, with an average concentration of 0.697 jug/kg (Table 13.1). Concen-
trations of HxCDF in treated soils were ail below method detection limits for
this analyte (<0.117 Mg/kg). A removal efficiency for HxCDF was estimated
to be >83%, based upon the average concentration of HxCDF in the un-
treated soils, and on the method detection limit for this analyte in the sol-
vent-treated soils.
13.13
-------
l; ill ,.;.[' I'iM P'-Ki " '' ., , '' yj!i"i MH
I i'tilll!!' ! ..." ' I! li, 1 ,' "I,,1 . I'Siiil!'!1 It , ; ! ,, '" jC'iiBli OJIHI
if- PI! ,ii, jlii : / ; liiiiivii ' 'I ii1, .iHfiii*. ii "'i if
Solvent Removal from Treated Soils
Solvent concentrations in tre^ solids range'd from 46.9 to 36 0 g/kg
prior to vacuum extraction, with a mean concentration 40.5 g/kg. Vacuum
extraction quickly reduced the residual solvent concentration, as shown in
Figure 13 5 The greatest reduction of residual solvent (39.3%, taken as the
mean of the five extractors) was observed following the first day of vapor
extraction! '''Removal of solvenf following the first day of treatment was not
regulable, yielding"only an aBSitional 9% over two days of treatment for
an overall mean removal efficiency of 48.3%. To comply with the terms of
an operating permit issued by local officials, no additional vapor extraction
was attempted. Full-scale operation of the TKRG's solvent extraction sys-
;"; ;; ; ; te^i^iyesopening'^^&^ systemuntil,resid
concentrations are below 10 g/kg.
Following vapor extraction, the covers were removed from the extraction
vessels, and a proprietary mixture of nutrients and microorganisms was
sprayed over the solids. Figure 13.6 shows the effect of biological treatment
bltrie residual solvent, asfa mean value offour extractors. Residual solvent
concentrations of the solids in extractor A were not used for this analysis,
because those solids were manually mixed with a shovel on a periodic basis
during this phase of the evaluation. No mixing of solids was attempted m
the remaining four extractors. Biological treatment appeared to reduce the
concentration of residual solvent rapidly during the first four days of opera-
tion This yielded a mean removal efficiency of 60%. On the fifth day of
biological treatment; the centrifugal blower was used to supply air to the
extraction vessels for a brief period of time. Following this operation the
mean conception of 'solvent "insoii(20:8 g/kg) was found to exceed rtie
mean concentration prior to initiating biological treatment (13.2 g/kg). it
was discovered that some solvent had not been completely drained from the
base of the extraction vessels and me solvent drain lines. When the blower
was used to add air to the extraction vessels through the drain lines, sending
solvent was forced into the solids, thus increasing the concentration of sol-
vent in the solids. Biological treatment proceeded for nine more days. Dur-
ing this period, residual solvent concentration in the soil continued to de-
cline The lowest mean solvent concentration in the treated soil (5.4 g/kg)
was from the samples taken following twelve days of biological treatment.
The mean value of the residual solvent concentration was found to increase
during the thirteenth and fourteenth days of biological treatment (9.0 to 10.0
g/kg, respectively). This observed increase in residual solvent
13.14
-------
Chapter 13
Effecl
50
45
S 40
1 3!
.a so
1 ^
CO
f 20
1 15
10
c
Figure 13.5
I1 of Vapor Extraction on Residual Solvent
i " "
-
i
\
>y
N .
\
^-=
*""^^^fcj
^
'^S
"N
0 12 3
Day
Figure 13.6
Effect of Biological Treatment on Residual Solvent
Average Solvent in Soil (g/kg)
ป U. 0 d C3 " c
S
"
b^
1
1
/
/
L "I
*!
^
k -
L ^
1 1
V
^
ซ
1 [
f 1
r^
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
Day
Data from extractors B through E only
13.15
-------
Case Histories
I! if.I ":. i'"'|i ' "In HI:! ""IB,
[in in ', 'I' i ii
concentrations could not be attributed to any operational event. Treatment
was considered "complete at this point; final samples were taken from each
extraction vessel (as reported above), and the system was decommissioned.
As part of these activities, samples of purified solvent were collected from
the holding tank and were analyzed for PCBs. Results showed that the puri-
fied solvent contained no detectable concentrations of PCBs (<0.33 mg/kg).
Therefore, the solvent may be reused.
ffiii-Scate Treatment of Pesticide-Contaminated Soil
Since completion of this evaluation, TKRG has implemented a full-scale
solvent extraction system at a site In Stockton, California. This full-scale
system used 19 steel roll-off containers for batch treatment of soils. Each
roll-off container was filled with 15.3 m3 (20 yd3) of pesticide-contaminated
soil and operated in a manner similar to the system described above (Figure
iS.l); Therefore, 290.5 m3 (380 yd3) of soil were treated simultaneously
within the 19 vessels. Twelve grab samples of untreated soil were collected
as the solids were loaded into the first extraction vessel. These samples were
composited and analyzed for pesticides (US EPA l992g). Three extraction
cycles were used to remove pesticides from the soil. Following the third
extraction, all solvent was drained from the extraction vessel, and vapor
extraction was initiated. A closed-loop vapor extraction system was used for
the full-scale system. Air was drawn throughTthesolids via a centrifugal
blower and passed through a reMgerated condenser. The condensate was
recovered and treated through the solvent purification system. Air dis-
cjiarged from the condenser passed through a heat exchanger and was fed to
"S "intake" manifold at the top of the covered extraction vessel. Following this
treatment, 12 grab samples of the treated soil were obtained, composited,
and analyzed for pesticides (US EPA 1992ft). Results from these analyses
are shown in Table 13.2.
.' 5 ' '^M-ic^b^^ni'e'ffectively removSd DgT,DDD, and" DDE from" the "
Stockton soils'.'" Pesticide'concenttaHons'in treated soils were <0.093 mg/kg,
with removal efficiencies exceeding 99% for each analyte.
Conclusions
These results show that the TKRG's solvent extraction process is effective
in removing PCBs, O&G, HxCDF, and certain pesticides from dry sandy
soils. Results from the pilot operation at NANSI showed that the
13.16
-------
Chapter 13
Table 13.2
Pesticide Concentrations and Removal Efficiencies
Analyte
EOT
DDD
DDE
Before Extraction
(rag/kg)
805
122
15
SouiceofSoil
After Extraction
(mg/kg)
0.093
0.024
0.009
Removal Efficiency
(*)
99.9
99.8
99.4
DDT Dichlorodiphenyltrichloroethane
DDD Dichlorodiphenyldichloroethylene
DDE .Dichlorodiphenyldichloroethane
effectiveness of the process could be monitored by measuring contaminant
concentrations in samples of solvent discharged from the extraction vessels.
Furthermore, this work showed that the solvent purification system was
effective in removing PCBs from the extraction solvent. The pilot-scale
work also demonstrated that solvent removal from treated soils by vapor
extraction and biological treatment was possible. Further reduction of re-
sidual solvent concentrations in solids is deemed to be likely with additional
vacuum extraction (>3 days) and biological treatment. The vapor extraction
system was modified in the full-scale system to include a heat exchanger.
The effectiveness of this modification was not evaluated; however, it permits
operation of the vapor recovery system as a closed-loop system, thereby
eliminating a potential source of air emissions.
The effectiveness of the process in removimg O&G was limited. This is
most likely due to solvent/solute relationships. The makeup of the O&G
fraction can vary depending on its source(s). The average removal efficiency
of PCBs was found to be high (98.8%) during this evaluation, while the
O&G removal efficiencies averaged 65.9%. Results from a previous study
using an alternative solvent extraction system had average PCB and O&G
removal efficiencies of 99.2% and 98.2%, respectively. This suggests that
O&G removal efficiency may be used as an indicator of overall solvent ex-
traction process effectiveness, but that it is of limited use for determining the
effectiveness of the process in removing specific organic contaminants.
13.17
-------
Case Histories
:,::/:::i: '...'-' I: '':'.~:: .." .::' ,:::' , ." Acknowledgments " "
rxENJiiiii*' ii! I.:/- ! Jill ; ::iiiiiiis rim :' :.?:; ,ir. ,ซ ;" Jibi ' ", ;,:ซ; : i.i IIM. ., i ซ;a*#. ia*i*iKWfflff iiaisffrafi nhwic,;1!-* .^'i,!.* ,i .?T.^V. nisi .",
llfif $t**T "5 . I'!'*'* ?W .' lit '*$! ซ-! '!!-''''The'authors which to thank all of the individuals who assisted in the evalua-
'' ^" ' ' ' -* - : -'"-:!! -* - ' ' 'Son of to technolo^: 'ISpecificaffyi' 'we iSognlze Alan'"Cash of the Terra-
^i'iLi :,i s-J^S-^V ,,;;, i/' -Biji /:;:^^'^^':'''R|sponse''Grbup,''an3''Ari%HฃlIrison'an^^
Station North Island for their efforts in seeing this work through to completion.
iiniiiii ii, 'ii'i'niii&iniiiiiip niiiiiii
it:1,, '.i1 ii iซ lie1"' ,.,,,1 ;;;, iiiiiiir j,1
References
i',im,\ ...... K;i ป.
i:^" JlfiJ*
, iti!
::"!i . Kt
' ..... 'IF
' : A .
im-
ป!t,i.
..... ! ;i"
. "?
- .?
i iiv il
II I!!'1!1111!!"!;1"1'1!"11"! :!f1.i;,;' . ' I,,!'1 \W,,r i,,'"' ' I'll: iil'JISil '>
lillllili/l! T si I
'J'J1'"11"1'"
, III '"11111 Ill'TI||'|||l,|i
, ',. IlifvL1,'<''''': , !, K,,
i"' ''iiluii ','" T1!' j! 'if"
1 i ,n .liHi i1 '.,,.; ซi <'i
, ' lUhFr f!> ""i,, ''"'L
. i' l1 ' , '.
Silt
'"'**! I! Ill',''''1"1'
' ':,; : . i il i " k ' '!; .
if;, 1 ,: l >|i i',,,!! l11 in'"i,,!"1' !i lillifi " j
^Program, Technology Profiles. EPA/540/R-94/526. Tthedition.
"Cincinnati,'OH. " ''"'"''" "' '" ' '""" " ""' '"'"'
2. U?S. Code of Federal Regulations. }994. TOfe 40: Pra/ec^n of
: L . ^rifJ1 :"' '
3. American Society for Testing and Materials (ASTM). 1992.
Standard Test Method for Laboratory Determination of Water
(Moisture) Content of Soil and Rock, D 2216-90. ASTM.
4. American Society for testing and Materials (ASTM). 1990.
Standard Test Method for Particle Size Analysis of Soils, D 442-
63. ASTM.
5. US'EPA. i992g. 'Test Methods for Evaluation Solid Waste. 3rd
edition* Office of Solid ^ie and Emergency Response. Wash-
ington, DC.
6. Meckes, M.C., T.L Wagner, J. Tillman, and S. Krietmeyer: 1993.
pernbnslratipn of the basic extractive sludge treatment process.
. if - , I,1 Jp Air & Waste Manage. Assoc. 45(9)1
' 1111' ' '!, <'",!!., I, ' ' I'lil ' III,!,, >' I
',' i,""
Li- ,'i'f.ii i*.
fl III!
'lijiuli';ปI"I mil I! Pi ' '""i U 1
t .......... " $iiiKiป
IIIU,1 'llilll'llll' 1 J 'i
. ,,iii';. Ti::|"!, mi *:r1,,'."!"':;;,;', , * '
!i:!" '.?" fail i !;"! ' ;, ^ \ ' ''' .iซ i- >
i, ;:iiJi'' ,' it, '
::: ปi,-;::": -. v",,:,/:,,',::;';, LSI3.18
/I'.; , j, >" '! 'i :",n.it i. ;:' v L ' "i i is
-:1;1!1"1 if 'I -I;:",,{!"!; Hi""""1 . :.; (v,
',:.i ' 1 : *: i
i ' "'I'i':,!: i',,8, 111
, ; j, :" '. ',:",(i..t i. i;-1:'lv L ?. ",i is ;iv* I''**' | n:!' !, ..ji'i s;*,' , H lix I'N air. JIM^ iiim^^^^ iป^ iniiiiii
-------
Chapter 13
Case 2 Removal of PCBs from
Contaminated Soil Using the CF
Systems? Solvent Extraction Process:
A Treatability Study
US EPA conducted a treatability study on soil collected from the Spring-
field Township Dump (STD) Superfund Site. The approximately 4-acre site
is located near the town of Davisburg, Michigan (Figure 13.7). Between
1966 and 1968 the STD was used for the disposal of drummed and liquid
industrial waste. Primary contaminants in the soil (a fine-to-coarse-grained
sand) include: arsenic, lead, and barium; volatile organic compounds
(VOCs); and semivolatile organic compounds (SVOCs), which include
PCBs and the pesticide dieldrin.
On-site incineration had been specified in the Record of Decision for
remediating the soil at the site, but negative public opinion toward incinera-
tion has led to the consideration of treatment alternatives. Based upon pre-
liminary bench-scale testing on soil samples taken from the site, the CF
Systemsฎ (CFS) solvent extraction process was believed to be such an alter-
native. Therefore, a treatability study was conducted to determine whether
the technology would be effective in treating soils at the STD to the desired
cleanup standard.
Approximately 525.3 kg (1,158 Ib) of soil was obtained directly from
PCB hot zones at the STD Site and then screened on-site to remove oversize
material (>l/2 in. diameter), which was approximately 76.2 kg (168
lb)(14.5%). Of the approximately 453.6 kg (1,000 Ib) of material screened
to
-------
Ilii
" !
-"ป*?
:ป' i
! ! I!
:: *:;
m-.-'ii* ^
: i
lis*!!> i-
Ii i IN r i; ! paii i
sit la = ! ; ;:"i:: a ; ---'- -? _/-
ro
o
; |! : ;: II li!
- - ; -= ,' ซ' r,;;1
- -_ i ซ M J I j!| I!!;
ป:s| !
SIS ifi ii] I ii I Hi:!
M si
1 i , ,1 . -^ ,
I I r> J BJ > 1
Figure 13.7
Location of the STD Superfund Site
N
A
i i:i -" " ' i i ! I
iMl! I
iiii iii iilli i
ti ซ ! II
;: ! ii
-------
Figure 13.8
CFSฎ Process Diagram
Co
fo
Water
Reclaim
1
Filtrate
\
Filter Cake
(Product Solids)
Liquid
Sample
Location
*
Solid
Sample
Location
Liquid
Sample
Location
* Process path used for full-scale system only
o
(D
-------
L^ " I"";."!
"at1, ill!
i' , ill,'1"! ., ft, b,,,!' '
!,":.!il,'.'!!'. I!,,:1,*"!!"!,,,1 ..i,',*1,!,:1! ,"
Case Histories
' At Hazen Research Inc., the feed material was air-dried, further screened
to remove oversize material (>l/4 in. diameter), and mixed to produce a
homogenous test feed. Table 13.3 summarizes the" results of the test soil
screening for removal of oversize material.
I hi, T I1'ill, , ,||| iiiiiii
Si Si-' ' :* .1!
:, t
Table 13.3
Percentage of Screened Oversized Material
Location
Starting Material Material Screened
(Ib) (Ib)
Oversize
Springfield Township Dump
Hazen Research Inc.
1,158 168"
-626 [[[ 26"
I;'"1;.' Total % ..... oversfze'S 1/4'in.
.nii!"'," ;.!!,
-14.5
-4.0
L-i'8.5c
IILIII ,. i';.
.1 i?1: ป!, I,
;',- ' ii: .Mill,!; iliii v.fii *K ป R
Using plastic crating having approximately 1/2-in. openings.
'Using an ASTM sieve having 1/4-in. openings.
'Oversize material could be treated following size reduction (i.e., pulverizing) during a full-scale remediation.
If
liilllllii
The contaminated soil was fed in 45.4 kg (100 Ib) batches into the extrac-
tor and thoroughly mixed with approximately 68 % (150 Ib) of solvent for
each cycle. Following phase separation of the solvent and contaminants
from solids, the solvent/contaminant mixture passes from the extraction
system to the solvent recovery system. Once in the solvent recovery system,
the solvent is vaporized from the contaminant, condensed, and recycled back
I'M' >I' ,!;!';!'" to the extraction system as fresH"s7flveht After all"extraction cycles are com-
::!|i!|:t 'IS :'<':;;,,,: pleted, water is added to'the extractor and mixed with the solids to aid in
1 , 'if,I! N | I'"1"1!"!1''!'1'1"!' ' ^i! 'I'lfilP ! 'Ii II1!"' "' I"11'1 :ซi' n '"'ป II "'i""!"1" "I ''''li11,,!','!1! 'W "" "i1 '"I'' ii '' Illl .li1!'m*1' I". I" i, jjjjilMli'JIII 1, JIIBBi * 'IBj i,, i" i i " I, A,' Ill"' In ปn; ,. n 'ป 'i ' ^"' J "" .'
removing any residual propane. Product solids are discharged as a slurry in
water and then filtered to form a filter cake.
... . , :.:. , ....... : :The primary objectives for the treatability study were:
IliJK
< li!ปi r 4:, iilllli
] {' ...... i1 T'Ki: ..... \,>, i ..... 'liilA1 ' : "K:; :
,:! L'l'-l'
I
" STD soil to
the remedial action standard (RAS) of <1 mg/kg; and
.', '' ""I.1 :: ' /, ':', <; !' I l'i ป illli I "l I j i i ' I I
., : " ! :'M'; 13.22
nil 'J'liil'.ii'liiluiliiH i,,,, iiiiml Hi'I irilnllllllliilllllllir 'ill' "I ,[,' vJll1"; ill! Win III!;
-------
Chapter 13
determine PCB concentrations in the filtrate water to ensure
proper disposal.
Secondary objectives of the treatability study included but were not lim-
ited to: verifying the absence of PCBs in the pilot-scale unit prior to testing,
determining residual concentrations of dieldrin in the product solids, and
determining mass balance for total materials.
The CFS pilot-scale treatability study was conducted in two phases,
which included a total of five main process runs. Phase I consisted of three
test runs, each consisting of a different number of extraction cycles. The
first run consisted of three 20-minute extraction cycles, the second run con-
sisted of four 20-minute extraction cycles, and the third run consisted of five
20-minute extraction cycles.
Preliminary analytical results, using hexane as the extracting agent, indi-
cated that the primary objective of producing solids having <1.0 mg/kg PCB
concentration was met for the three-cycle run. Therefore, Phase n consisted
of two additional test runs using three 20-minute extraction cycles each,
since this process condition was believed to be the most economically fea-
sible in achieving the objective. It was later determined that these prelimi-
nary results underestimated the concentration of PCBs in the treated soil. A
sixth run consisting of two 20-minute extraction cycles was added to test the
limits of the pilot unit in treating soil to the desired levels. Table 13.4 sum-
marizes the process conditions for all six runs.
Analytical Results
Sampling was performed in accordance with an US EPA-approved Qual-
ity Assurance Project Plan. The critical process streams sampled for each of
the six runs included: feed soil; product solids (filter cake); and filtrate water.
Samples of the organic extract were taken at the end of Run 6, in order to
perform a mass balance on PCBs.
Table 13.5 summarizes the MDU's PCB percent removal efficiencies for
each run and as averages of all six runs and the 3 triple extraction cycle runs.
Oil and grease (O&G) analysis was also conducted on feed and product
solids for each test run to determine propanes capability in extracting semi-
and nonvolatile organic compounds in addition to PCBs. Results of the
O&G analyses are summarized in Table 13.6.
13.23
-------
!i i ;1 ซii ilil
I! f ง |jl PI
< I1
h:: I'ii i i i
Ml; ihi i ! 1
! i :'; f:1:' , _ M = = li
- 1 E ! :,\ i ,,il i = ! ! 1 = I:
,
,J ; j s V: ' ji ! ; "
s F ! = =
- = : i - I . :
Table 13.4
Process Conditions for all Test Runs
Feed Number of Mixing Time
Run Loaded Extraction Each Cycle Mixing Solvent/Feed Ratio
Test Phase Number (Ib) Cycles (min) Speed (by weight each cycle)
1 1
2
3
n 4
5
Added Run 6
100 3 20 FuU 1311
100 4 20 0/FuH! 1.5/1
100 5 20 FUU 15/1
100 3 20 FuU 15/1
100 3 23 FuU 15/1
'100 2 20 FuH 15/1
-P
=
:
Extraction Pressure
(psi)
Average/Range
315/250409
261/223-308
238/182-294
266/202-309
243/194-299
277/231-319
a i i
; IB | : ; S
n ; E
= 5iป
"f
: SB s :
^ ' ;
- ~
"i
Extraction Temperature
OF)
Average/Range . : : .
133/125-138
122/106-133 ' :
117/93-150 -' !;
124^8-140 ^
119/98-137 J ii.
125/110-138 : L
During one of the four extraction cycles, the mixer was Inoperable; however, a solvent flow was established by recirculating propane from the top of the extractor into the bottom. r
j ! hi
o
CD
1
(D
en
;
E
i
ป
i
I (I
-------
Chapter 13
Table 13,5
PCB Removal Efficiencies
Number of Product Solids
Run Extraction Soil Feed Concentration1 Concentration1
Number Cycles (mg/kg) ! (rag/kg)
1 3 210 4.9
2 4 240 1.8
35 340 22.
4 3 3102 ; 4.02
5 3 220 5.8
62 220 19.0
Average3 260/250 6.3/4.9
% Removal
97.7
993
99.4
98.7
97.4
91.4
97.6/98.0
'The test method used was SW-846 3540/8080; Aroclor 1254 was the only PCB identified.
2Average concentration of analyses of field duplicate samples (see Table B.7).
Two values are given; the first is the average of all six runs and tho second is the average of the three extraction cycle
runs (Runs 1, 4, and 5).
Table 13.6
Oil and Grease Removal Efficiencies
Number of Product Solids
' Run Extraction Soil Feed Concentration1 Concentration1
Number Cycles (mg/kg) (mg/kg)
1 3 4,480 112
2 4 4,560 73
3 5 5,870 <20
4 3 5,460 133
5 3 5,140 93
6 2 7,060 279
Average2 5,430/5,030 < 118/113 >
1The test method used was SW-846 9071 .
*Two values are given; the first is the average of all six runs and the second is the average of the three-
runs (Runs 1 , 4, and 5).
% Removal
975
98.4
>99.6
97.6
9S2
96.0
97.8/> 97.8
extraction cycle
13.25
-------
fill II
II lull i
Case Histories
ire*;,: !!!!; i, iiift>. fiii;:,,:ซ. ;aan.iry... miff'; iii, j>.
,:'>'] llll|llli:|i;iK|r.il.i: '?!, Till
llllill l ill ( I III
Illllllllil
ijiiiiir
Ilillllll illllHlLtl','
f Illllllllil1' i",IT in i \ IL ;
liiiiiiiiiiiL ' i' 1 "
:
'-(IZIII , I1:::
'I J 'I" " mill"
'! aiiiiib 'i I-1 'K
iv !"mf
HllV'iki | lih'iin mir
iifi
PCBs were not detected in the filtrate samples collecteS for the five main
test runs (<1.0 Jig/L). However, for Run 6, which involved only two extrac-
tion cycles, PCBs" were ^detected at'lJ jjgiC! the"p^ucfofl'OTllectelifi'i'fi; I"1 Jf";::i-1, '' j';'ifc $3M.'*JWtW k''i'SliKf ซ%.'HBiili* JWttJ'ita '!w:/' ซ'if&f ..< xJM.t Pi* Hlfr ซB'i'SHim
There were several quality control analyses conducted to evaluate the
ill -.'irin t'!.'.'it: >.1 I-K.I" i!1'1 i: .. a.. .,bi'tiiiii': .111.r''.r ., .1 * / , ni... -r, , , _,
laboratory performance. These results are discussed in detail m the full
report. The critical target analyte (PCB Aroclor 1254) was spiked into both
a sample of the product solids and ihto'a samplei"of'"the product water to
determine the accuracy and precision for these matrices. The results of these
rnitrixspl&ei/maMx'spi^^ show
that accuracy and precision were obtained for both matrix types and that the
project quality assurance (QA) goals were met.
llliN , i ,i, '" ; ' ., i MI ' IN ii , i i
13,26
ir i" :
ilii1! inhlll'lrllln liUIHII'i'.
Illlllh]', llllllillll'IL'aiEillllllDllliilliiiirll'iJ"1 4'lllliiJilllli'Tllllii JJIIiiHIIH ,
tMlr: Ill I 111.;ซ!.,I ';,,'III .'I'1"
-------
Co
vj
Table 13.7
Total Materials Balance
Run Number
1
2
3
4
5
6
Total
Feed Soil1
45,400
45,800
45,800
45,800
45,800
45,800
274,400
Input (g)
Water
52,600
80,800
93,800
88,500
99,500
103,000
518,200
Output (g)
Total Oil Extract
98,000
126,600
139,600
134,300
145,300
148,800 3,700
792,600 3,700
Slurry
71,600
147,400
116,200
134,800
141,200
158,800
770,000
F-l Filter Solids
485
485
485
640
640
640
3,380
Total3
72,090
147,900
116,700
135,400
141,800
163,100
777,000
Recovery (%)
Material
73.6
1172
83.6
101
97.6
110
93
'Runs 2-6 include the addition of 454 g of sand to fill void space in the extractor.
2Solids not flushed out in Run 1 exited at the end of Run 2.
totals rounded to four significant digits.
9
Q
TJ.
(D
-------
iiiiiii i inn 1 1 Hill 1111
nil 1 11 in in ii it nil in i ii ii i i i mi i linn
I (111 ill
111 ....... I
Case Histories
It
Table 13,8
PCB Aroclor 1254 Matrix Spike/Matrix Spike Duplicate (MS/MSD) Results
Sample
Product Solids
Filtrate
in i ,._^^L
Spike
4.9 mg/kg
10.0 |ig/L
Sample
Concentration
4.1 mg/kg
< 1.0 ug/L
MS
8.2 mg/kg
9.0 ug/L
MS %R
84
90
1
MSD
9.1 mg/kg
7.8 ug/L
MDS96R1
102
78
RPD2
*>
14
^"The QA objective for accuracy was a recovery of 50-150%.
c' c
ฐ
% Recovery
ซ100
_
where: C ' = the measured concentration In the spiked sample;
C0 = the measured concentration in the unsplked sample; and
C, = the known concentration of analyte added to the sample.
*The QA objective for precision was an RPD of S 40.
(Maximum Value-Minimum Value)
(Maximum Value+Minimum Value)/2
(Bi*iปs!.ป ..... i
jPlln'iil Illl. I,';.' 'I
,,
1 win ii 'nil
" '.'sis. jr Jiiซ '
-------
Chapter 13
Table 13.9
PCB Aroclor 1254 Field Duplicate Results
Sample Matrix
Feed
Product Solids
Product Oil
Filtrate
Sample Result
350 mg/kg
4.0 mg/kg
1 1,200 mg/fcg
< 1 Hg/L
Result 2
260 mg/kg
3.9 mg/kg
1 1,300 mg/kg
<1 Hg/L
RPD!
30
25
0.9
NC2
'The project objective for precision was an RPD of <, 40.
2NC = not calculated
four-extraction cycles conducted during Run 2. The two concentration val-
ues, for Run 2 (1.8 mg/kg) and Run 3 (2.2 rng/kg), are essentially equal
since they are within the range of field sampling and analytical error. How-
ever the O&G analyses conducted can be used to supplement the interpreta-
tion of results, with respect to organics removal in general. As Table 13.6
indicates, when the O&G data are evaluated, the five-extraction cycles used
for Run 3 appears to have performed the best for overall organics removal.
The performance of the runs relative to one another is illustrated in Fig-
ures 13.9 and 13.10. These show the removal of PCBs and O&G, respec-
tively, for each test run as the decline in contaminant concentration from
starting feed to product solids as sloped lines. Both figures show the dispar-
ity in performance between test runs for the respective parameters, which
may not be as apparent when simply looking; at percent removal values.
Figure 13.9 clearly shows that Runs 2, 3, and 4 came closer to the test objec-
tive, assuming a feed concentration equal to the average of all runs (250 mg/
kg). Their slopes essentially parallel one another. Figure 13.9 also shows
that Runs 1 and 5 had an almost identical performance and that Run 6 had
the poorest performance. For O&G removal, Figure 13.10 indicates that
Run 3 produced the cleanest solids, while Runs 1, 2,4, and 5 had similar
performance. Again, Run 6 had the poorest -performance, indicating that
greater than two extraction cycles are required to achieve O&G removal
efficiencies >96%. These results suggest that the extraction process
13.29
-------
Histories
Riij^jl fi''i l jjjik i,; Sฃl,:' igij', i| "V> /": |,. |:;" ;;,,' l'i, > ^ ] j^ijiv -^.^: \, , -^Wi f-ift iSj$i: '^H1'l ^' '^' ' *$$? $ ^ ' '^ilfflSK III 111!
! !lii lli,,;Jlll!lr, ii 'il Illlliilili I'Hi: Inli I',; lit, , "I,:!11!'! Ill1 ("Hill
i 'i i an, mil1, -i,
iiEiJiii;1,,;
..... IK'-iii ' iiijiii' '. ...... iSii''.! ' :ซ, 'ii.')*. "'f ''
ii.i'iiiiu .. ::
;;"::: '.;,
3!" iiiiii Ti,iE" .< > I;!
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i !, "!' I,,*',! l>, ,11 (!<,
ii::,: :: " J" '..iiiiii-ii
llliptll1 vi, i? i, K, HI;,' i; ii
IlilEil ;, ' i'1;-! 'i1;:'!"!;, n,
Kill; 1 ,1.1. !_ ,11. I. .17
iFiin fi "" ;n " ' i iiiiiii
iiiiiiiiin1 :t,. ' "" 'in 'is IIF
,::: : ;,; , '; ,~.
SSiiir 1! II'1 ! ,i ' ' !:, '' i!!!"T
ipift;:' ;.fil
*, :1 ,1 "1 i, "i ' i' ,| 300
i! ' ; , ' '''ป 'itfl
i jo i .' v ป y
; Silj,,, "i;!1,1!1,; ;:, ' : 'i , fe.
ง 200
li.lili.llllllll II,:.1,,1, ' S
S
o
I""!!!" ' lll'i " 'i.'l" QJ
.1.11111' i ,!", ' f. -a " " 100
:,::,; "'!
ii',,1,!1! '! ' ! , ' ,!", ."',;,n:'" '!"'!"' "in.1 ป!ป';
'isii^.^Mii' ':!='' ':::ii,;, i.:.
\
\
\\^_
\r4")
S\" VP.
\ซ%x ""--ฉ
\ . YX\ ""--..
\ ' /o'^':>- "--
^ \\ V\ """"-...
\ f*\ \\ \ ---,
\, ,,\ , \ฃL>\ . . "*--
12345 10 15 20
,', i-'ii-'ak. .niini1 i iiiiiii in iiiiii i iiii|i|i(ii||ii iliillllilllliilllllllll in i :il,)liiiv iMi'''!'')':!')!1 .T^iyiiiiii'iii.H^^^^
Product Solids Concentration (PCBs in mg/kg)
(f) Run number
Test objective
:::::: 3 extraction-cycle runs
- - 4 extraction-cycle runs
5 extraction-cycle runs
2 extraction-cycle runs
'!! :! "I1, "IB1
fiiir:li.,
"i ..... (ii ..... !' :
Ill": i'1
, i ' , ;ii:,l ..... i, i",.;:.; i, .'III 1 .....
, : :: ฃ! '!'!;;?' ' ,: .....
' , ;" , ;. ' "ill' ...... in .
. , ^ ..... i- "! ;!;
i .siiis, ii-!,,;: tjc;:t'ปfitjSiiiiflH';i;aBur
i ; !: -wi-ma w.;iwisซpxf '* ^t
operating conditions could be further optimized to yie
efficiencies than were identified in this study.
iililili -i jillfM^^^^^^^^^^ ii! ii irF,, ,'.{ Ill IF.:1, V; illi!!1 i ]i'!;!', liiiij-,::;''!)-:
'.i;" y:'(**i!i"fcii((m''iuH i
er remova
II lllllll Ii III II' III II
lllllll 1
1
lllllll
Another important conclusion that resulted from the study regarded the
volume reduction of ihazardous>, waste. Although the CFS solvent extraction
process is not capable of destroying PCBs and other contaminants present in
the STD soil (asl^'the'case ''with solyent'ex in general)!
it is a means of separating those contaminants from the soil, thereby reduc-
ing the volume of hazardous waste that must be treated. This in turn rggucgs
the cleanup costs" mvoifveicl. liie'cumiilative masTdFthe wet'contammatecl
feed soil for all six runs of the treatability study was approximately 274,000
g. The mass of the oily extract sampled at the completion of Run 6 was
approximately 3,700 g. Therefore, the process reduced the overall mass of
the contaminated material to ^35% of jjts original waste mass. The volume
13.30
-------
Chapter 13
of the feed soil [SG=1.34 grams per milliliter (g/mL)] and oil extract
(SG=0.87 g/mL) were approximately 204 and 4.3 L (53.9 and 1.1 gal), re-
spectively. Therefore, the process reduced the; overall volume of the con-
taminated material to 2.1% of its original waste volume. The highly concen-
trated oil extracted from the CFS process is either destroyed by incineration
or chemical dechlorination.
Figure 13.10
Oil & Grease Removal Trend
7,000 r-
3
*ปx
c
o
1
ca
8
I
b
4,000
3,000
2,000
1,000
\ <:
\ ^ '"*'. *' ""*
1 ^ **"* I*" \ ** J^^k
I ^ ** ' C^X f6y
. 1 \ '\ '\ ^^**^^
\ * *'ป"* ***ป ^ ^ N
1 * '*''. '\ s>>>
\ ^ ''\\ \ ^"^H
1 (1} Vv\ \ s%Ssv
. CW \ \^. \ -**
\ * r*\ ' s
i i * \ i \ '' i i i s*- i
0 *.ni\ ntfr\ in
30 50 100 150
Product Solids Concentration (O&G in mg/kg)
300
Q) Run number
" 3 extraction-cycle runs
- - 4 extraction-cycle runs
5 extraction-cycle runs
- - - 2 extraction-cycle runs
13.31
-------
Ill
Case Histories
lllnil.C i I: I if ''''!,!li" < " llll'Tlii,!1 I:1!1"!' "i '! 4ซ ,' IP1 (I , I1
-------
Chapter 13
Figure 13.11
Block-Flow Diagram of the Biotherm Process1" for Refinery Sludge Treatmen
Sludge
Evaporation
and
First Solvent
Extraction
Water
Solvent
Slurry
Solvent
Multi-Stage
Solvent
Extraction
Solids/
Solvent
Cake .
Desolventizing
Solids
Biotherm Process Battery Limits
Solvent
+
Oil
Solvent
Solvent/Oil
Distillation
(In Refinery)
Oil
The solvent also prevents scaling and fouling of the heat transfer surfaces,
thereby assuring good heat transfer. By evaporating the water, problems
with emulsions are avoided, even with "difficult-to-process" feeds.
Depending on the water content of the feed, a single-effect or an energy-
saving multi-effect water evaporation system may be utilized under mild
process conditions (<5 psig, <121ฐC [250ฐF]). Next, the dried solids/solvent
slurry is fed to a multi-stage counter-current extraction unit Where the solids
are contacted with additional clean, recycled solvent until the desired degree
of indigenous oil extraction is reached. Finally, the bulk of the solvent is
separated from the solids by centrifuging. The residual solvent is removed
by "hydroextraction", a desolventizing step that uses hot recycled low pres-
sure inert gas to vaporize the solvent from the solids at relatively low tem-
peratures (<177ฐC [350ฐF]). The product solids contain minimal percent-
ages of water (<2%) and solvent (<1 %).
The spent solvent containing extracted indigenous oil is returned to the
refinery and reprocessed. Alternatively, a solvent/indigenous oil distillation
unit may be included in the Biotherm Process facility to separate the solvent
for reuse and recover the indigenous oil for disposal. The solvent is
13.33
-------
s* \"'m> lit ;:
Case Histories
"i in
111 Si1: ' ,'j ; ..... ;i ..... "
IK
*'ii:
: '
' I'-1
typically a narrow-cut refinery hydrocarbon stream with a boiling point of
about 204ฐC (400ฐ"F). Food-grade TsoparL or other nontoxic hydrocarbons,
including alcohols, are also suitable solvents depending on the application.
The combination of water evaporation with solvent extraction in the
Biotherm Process results in many technical advantages:
any emulsions initially present are broken;
emulsion formation during processing is prevented;
solvent extraction of contaminants is more efficient; and
if metals contamination is a concern, the reduced volume of dry
solids product may be stabilized(fixed^ or otherwise treated
jig:;,;];''ii; ,i,,;:,-. 7jj, ^. ,*..; ,;:,: ' 'f;;, . . more;readily for'Iandfill disposal.
' ii
Refinery Waste Treatment Standards
งVf Hazardous, listed,wastes generated by oil refineries have been categorized
. ' " 'j "'" i,,,'"' ' ' iiliijig!!ซ' ii i! iflllT1, ' '1 '!!fป,, "' " .ill1',' /i1' jii'! ' "' i ',,,'I'',,|,'i!"v"i!,"1" ;V' ''|!f' ."''li'l'il'".:..* ili'iiiL1"1'ป rซ\f, I -III 'fc^iMllH'11:!!! !ii'ป mi "nil 1'iM" .yiiiiii'Wili'',!,1', '''ilii,, f'Mlm" ',. niiiill v1 !,mil1,: ,,,:ij|j,||i| ;'| Jsu, if: |i if ,i i<;Hlii ."'Hii1'1,1
., ',1 i;:,;: ' ;Y . "!' p." ||| i; by toe US EPA under RCRA as follows:
J,::! ,f'i, C 7 ";';", i '" '''';, K048 dissolved aVfloatS^
III"1'! "i i'!1".1 i., - III,111"!"!!?!,1,, l'il!*i ', '''"II ", !' '" Nf'iii.,1 ,!!! , :i|i,|iป inililli ',lii, ' I I!!!1!,!,!,,*''! ailliri'ill'lil,, fl il,i!|if,,,'l |,,',:i''i|i! I'll! 11, il" J" , i ,'i',l' i , ' ,i'' ,1,, in ' !lllii|l,,,,|":ili 1,'ilii, ,| '
F" t :. I" ' '" i, i! i, Mi! ' ' ' .' , 'ป";": ", ' ' ''.''" "'!';! '< '> '.'"", i:; i (I" 1 't ''tfBCfflfUr "i11*1! ."iSi ! V.'',": ii I Cr' :'T: f'' Ji If I i::,, ':,, J "i ": T KM ill" ill ' K ' "!'{'* ill
ilj'ji,,;,; ; " "'iiff , iji''" |, :. ,',ปi''K049 slop oil emulsion solids;
;;;:;;;;;,;;'.'. .-;,;, ' ;,:; ;,;;;; ' .." '"': .'.,!. ''.".<.''''' ;-.::;'--,:.ป-:";^^; ;. ;,]':. \ ':.:'..".. ;:,:.. ,'.:;, ;,,.: ;;;;;;:: ;;;;
* K050heat exchanger bundle cleaning sludge;
K051API separator sludge;
;;:":, ,""::.;. i;:;; '." '',,:'l": : "" K052 leaded tank bottoms; ,,..,'., ,,
F037 primary oii/water7sbiids^ separation sludge; and
F038 secondary (emulsified) oiVwater/soh'ds separation sludge.
7"; i'i , : ii" 'li'"1 '... 'I;.' " i^atrnent^standards^for^
the BDAT Standards and those for hydrocarbons from these Refinery K- and
F- wastes
IlSPi" ,:t: ' "ill1!" i*!!,: !:'li ;.;.. '
i; , "s ; ,;.'", I" ]'.''..'..' Pjroceงs,,wni;notrempye_ these, m^tds,,fe
abQve, overall volume reduction of the solid waste and removal of the oil
and water will usually permit more economic treatment of the residual met-
als-containing solids via solidification (fixation) or acid leaching, etc.
By separating the individual components of a waste stream which in turn
allows them to be recycled back to the refinery and incorporated in a refinery
I
-------
Chapter 13
product, the Biotherm Process meets the criteria for the "closed-loop recy-
cling exclusion" of RCRA (40 GFR 261.1[a][8]; 40 CFR 264.6[a][l]-[3])
which reduces the waste treatment permitting process.
Table 13.10
US EPA Best Demonstrated Available Technology (BOAT)
Standards for Refinery Hazardous Wastes K048-K052
Hydrocarbon Compound
Benzene
Ethylbenzene
Toluene
Xylenes
Naphthalene
Phenanthrene
2-MethyIphenol
Anthracene
Benzo(a)anthracene
Pyrene
Chrysene
Benzo(a)pyrene
Phenol
4-Methylphenol
Bis(2-ethylhexyl)phthalate
Di-n-butylphthalate
BDAT Specifications (ppm)
14
14
14
22
42
34
6.2
28
20
36
15
12
3.6
6.2
7.3
3.6
Biotherm Process Treatment of Refinery K-Wastes
Tables 13.11 and 13.12 present analytical results on feeds and product
solids from laboratory simulations of the Biotherm Process on API Separator
Bottoms (Table 13.11) taken from an operating refinery and Lagoon Sludges
(Table 13.12) accumulated from oil refineries and other waste sources
(which include chlorinated hydrocarbons) over a period of many years.
13.35
-------
' '! Illn , ill1!,,,.
"i l\
f;, S"|j 1
Case Histories
"I "III" i ,11 'Hill1 " hi, 1 ,, I "I ill'l '
,i">"nii an1,1;I"1 a,
/it;
Table 13.11
Biotherm Process Analytical Results After Three Laboratory
Solvent Extraction Steps on API Separator Bottoms
Component
Water
Solids
Oil and Grease
Benzene
Toluene
Ethylbenzene
Xylenes
Naphthalene
Fluorene
Phenanthrene
Feed
76.5% (by weight)
3.6% (by weight)
19.9% (by weight)
50 ppm
50 ppm
670 ppm
360 ppm
3.5 ppm*
3.0 ppm'
'sฃ ppm*
s"1!' '"J "i": f-iiih'i-i "iisis:, !:,' IF i ,t" " if ""!, %Removal,
Product Solids Solids Basis
0.4% (by weight)
II
99.4% (by weight)
0.2% (by weight)(TPk)
u '"
I
1.2 ppm
u ' l:
'"u "
. , i ,, ซ,| ,, .. I ,ii
II
1.1 ppm*
, ' "", ,;, , , " ; , j",1,;
8.4 ppm
99+
99.9+
99.9+
99.99+
""::"99.99+"""""
93.1
98.7
942
Comments
-
''
Meets BDAT
Meets BDAT
Meets BDAT
Meets BDAT"
-
-
Approximate, below limits of reliable quantltatlon
TPH Total Petrolaum Hydrocarbons (US EPA Procedure 418.1)
U Undetected, % removals based on minimum detection limits
BDAT Best Demonstrated Available Technology
'", i;: I-
i
In both cases, the water was evaporated from the feed sludges during the
first laboratory extraction which was followed by two extractions using fresh
Isopar-L solvent. This closely simulates the counter-current extraction of a
commercial unit in which fresh recycle solvent is contacted with the
I i : : I' !,:- ! '. iป";r M ., 'I'"!" ":; t, "JIU Ait , i. , , i ซ,, .ซ,.ป. a < - -^ _v -
"cleanest" solids to permit final traces of contamination to be removed. Ex-
tractions were performed at approximately;"1'OA solvent to solids ratio at
about 93ฐC (200bF). The number of extractions, the solvent to solids extrac-
tion ratio and the actual solvent used may be adjusted for the commercial
operation to optimize the contaminant removal according to the specific
project's overalltreatment targets.
i ป" js:^,' '.in, jj, r^ ii|i,v Hi ,, i,:."1 j,^ i'ป!,, 11 ih'1. ,: ' | ;, "11 '"'" jur f : i.<, ".iPi....;; uJijii:,'1";;,1111., j ;: '" i iMJ'ii.:,'1 |; i ni ,;,,. iป" i; !i * , ซi.,,,:J|i;ll!i!.j"i!i'j '$, '':...ซ . it1,''!'!! r1",?1 f''111'!!*!1'1'"' ''"i'!
Asshown mtables 13.11 and^13.12, removal efficiencies of specific
contaminant compounds based on the solids present in the sludge feed were
nearly always more than 99% and in most cases signficantly higher than that
when there was analytically reliable detection. In virtually all cases, the
13.36
-------
Chapter 13
1
Table 13.12
Biotherm Process Analytical Results After Three Laboratory Solvent
Extraction Steps on Refinery (and Other Waste) Lagoon Sludge
Component
Water
Solids
TPH
BDAT Compounds
Benzene
Toluene
Ethylbenzene
Xylenes
Phenol
m,p-Cresol
o-Cresol
Naphthalene
Acenaphthene
Huorene
Phenanthrene
Di-n-butylphthalate
Anthracene
Bis(2EH)phthatate
Pyrene
. Benzo(a)anthracene
Chrysene
Feed
34.6% (by weight)
14.6% (by weight)
28.0% (by weight)
ISO ppm
530 ppm
530 ppm
1,400 ppm
1,600 ppm
240 ppm*
200 ppm'
2,800 ppm
320 ppm*
830 ppm*
2,700 ppm
330 ppm*
320 ppm*
1,200 ppm
600 ppm*
100 ppm*
170 ppm*
Product Solids
0.5% (by weight)
99.0% (by weight)
0.5% (by weight)
2 ppm*
4 ppm
V
1 ppm
35 ppm
7 ppm'
3 ppm*
1 ppm*
U
1 ppm*
13 ppm
2 ppm*
10 ppm
35 ppm
6 ppim*
2 ppm*
3 ppm*
%Removal,
Solids Basis
99.9+
99.6
99.8
99.9+
99.9+
99.4
992
99.7
99.99
99.1
99.9+
99.9
99.8
99.1
992
99.7
99.4
995
Comments
_
-
: -
Meets BDAT;
TCLP = U
Meets BDAT;
TCLP = 0.05
Meets BDAT;
TCLP = U
Meets BDAT;
TCLP = U
TCLP = 0.15
TCLP = U
Meets BDAT;
TCLP = U
Meets BDAT;
TCLP = U
No BDAT;
TCLP = U
No BDAT;
TCLP = U
Meets BDAT;
TCLP = U
Meets BDAT;
TCLP = U
Meets BDAT;
TCLP = U
TCLP = U
Meets BDAT;
TCLP = U
Meets BDAT;
TCLP = U
Meets BDAT;
TCLP = U
13.37
-------
Case Histories
jillillll! i
fix :<:
IIIK'I1 ;"f - liiirl1 ' HIM 'ilU
IE: 1,1 I1!,-.
H lllllll > I i"1'",!1!" is l"
!1' ' I' ' 'I'v: II 'lll'llilllr,
' h:*:! I1' '!'!!*
"1 : "ii,l,ป". li I, ill lill' '
, n r^T1?
1 ::, In I i
"hi ' It
pi k.,;',, ':',l,,-;
111 11 ii1, -"H!" I , Ill
lii f1 ii:', 'Mil
'! Illllh, "'iHiaill, IJi
ilt"J'i|:':i'iL"'-:,: ; ..it nil,!: J Ifiiil
Table 13.12 cont,
Biotherm Process Analytical Results After Three Laboratory Solvent
Extraction Steps on Refinery (and Other Waste) Lagoon Sludge
i:'":: 'i'i ;;,. !Uii|.iiiii'i''' , jinn!!, nil
' '1,11m: !i, 'Hi:: ,''',',.ii|i.|,'i!,S'' '
,';!;"'Ill ,i!"' I "fl'ff ;,"i!,!1 ,,!!' ', r ' "S,
"'jiA' M" '"'!
Component
. "i"! i"i.i ...... lll.i11. "' ..... .'' '.' I ''
lliiiiiil1'1';..!.!.'1""
' "'
Feed
. . . ..
i. ...... i ...... ft,,;. i|i ; ,:,, | | ;. i"||n;'',j. ,(":',.. ll201R.ia,i
Product Solids Solids Basis Comments
Other Hydrocarbons
"; Styrehe
2-Methylnaphthalene
Acenaphthylene
Dibenzofuran
Butylbenzylphthalate
Di-n-octylphthalate
Fluoranthene
Chlorohydrocarbons
Methylene Chloride
1,1,1-Trichlorethane
Trichloroethene
1 . 1 ,2-Trichlorethane
V " , i*
Tetrachlprpethene
Chlorobenzene
1 ,2-Dichlorobenzene
Hexachlorobutadiene
Trichlorobenzene
Pentachlorophenol
Hexachiorobenzene
l,000ppm
5,600 ppra
450 ppm*
100 ppm*
480 ppm*
1,100 ppm
330 ppm*
. '.. ., ','H
72 ppm
240 ppm
190 ppm
19 ppm*
. L" , ' i . 1, V,
260 ppm
72 ppm
790 ppm*
1,200 ppm
440 ppm*
4,7 15 ppm
360 ppm*
il
' 12 ppm '
" 1' ppm*
16 ppm
2 ppm*
4ppm*
5 ppm*
u ''
' 'u"
u
u
1 ppm*
III III'" 1 IHIIIIIIII 'III111' IL 1 lilTlK 1 ' T', IA.I
u
: ' ii '
u
u '
U
18 ppm*
u "
1
99.7
99.99
99.0
" ' 99l
99.7
99.9
'"'"99.2"
!'": '' " "" '
' ' " 99.9+
99.9
99.9
99.1
"'i, . ' , r ,iid"i!'ii.i"
99.9
99l8
99.7
99.8
99.4
99.9
992
TCLP = U
f CLP" = ll
TCLP = U
" TcLP="fJ '
tctl? = 0,
TCLP = U
"TCLP'^U
TCLP = 0.51
TCLP = U
TCLP = 0
TCLP = U
. i, ''i1 ;",!!, 'ซ '"in,, iiji1 if '..si'iiiiiii'j: i;<,ซn
TCLP = U
""'TCLPVU
TCLP = U
TCLP = U
TCLP = U
TCLP = U
TCLP = U
,: " ' , 1,,,, , , , III"1;!!!"1 mi i,ili "Thiii! ' '.i ,ป!,:!!,; Hi vi r> > I1.:,!! i Tail1;,'I KI i" !ป" ,',i ' "I "I!!1:
, ",, , " ,,,ป:, i'1'1 'r , '"', :, - ii' , H ml1, , I " ii1, f "h"'" ป'ป j "'IT: ,i. *," J'ili !' h 'll'i.l il"i Til H !' :, " ", i,, ft i'i,
, f "iii,,'",f ' , 'l !, ,, : , ill , f ii, "' ,1" : : M;, b ' i"" 'i I1:',]!,1 i, i",! ,,t hi,"'',,:,:'Siii;I "'?' i11,: Hi"1 .if, " i V1' ''..i1
Approximate, below limits of reliable quantitation
TPH fptai Petfoleum flydnidarfions (US EPA Prbcidure 418.1)
U Uffiitecfed. ฐ/o removals based on minimum detection limits
BDAT Best Demonstrated Available Technology
TCLP fpxfcity Characteristic Leaching Procedure (40 CFR, Part 261)
"iin1,, ,1,,,'iiiiM1" i,: 'if i! ' 'inr a '
" L. In,:!. I i'l ! "link1! T1! i!lll"!",."
1 iiiiiji'iiiii1 'iii'iniiiiiiiiiiiiiii'ii' 'iiiiiiiiiiinii!11!! jr! ' ci ' nil
;-|IH^^^
.'iiiiiiii't'iJMr'iir'iihiiiiiiiiiiiiiiiii.iiiip 'Mill,' "!' '' 'unn
: ,:.,! t V,' rซ\v
BDAT standards for refinery hazardous waste hydrocarbon compounds are
ffibt It is noted that'}ichleylng''refiheiy "hydrocarbon BDAT levels may not
be the only remediation criteria for the lagoon sludge (Table 13.11) since it
contains' hydrocarb'bn and chlorinated hydrocarbons which are not included
in the refinery RCRA standard.
i" t
.iii;'::.^ 'ง&*
-------
Chapter 73
Only the partially oxygenated aromatics rn.p-cresol and bis(2-
ethylhexyl)phthalate failed to meet the hydrocarbon BOAT standards (Table
13.12). There is some concern in the industry that the apparent high levels
of the plasticizer bis(2-ethylhexyl)phthalate may be artifacts of sample han-
dling procedures due to leaching of plastic utensils or clothing (gloves, etc.)
containing the plasticizer prior to the analysis. This, coupled with the belief
that refinery wastes would not typically contain this manufactured petro-
chemical product, means that the presence of bis(2-ethylhexyl)phthalate
must be carefully verified in a specific feed before too much effort is ex-
pended on its removal from the waste.
To illustrate the flexibility of the Biothernt Process in a refinery waste
treatment application, it is also possible to use only the water evaporation
(drying) feature in certain circumstances. In this case the dried solids are not
desolventized but remain with the solvent either in a centrifuge cake or a dry
slurry. This Biotherm Process product is then fed to a coker (Elliot 1992),
asphalt plant or other suitable refinery operatiion. Here the "solvent" is typi-
cally a higher boiling hydrocarbon like a fuel oil which is a component of
the feed to the downstream refining unit (e.g.,, coker).
I
Biotherm Process Pilot Plant Treatment of Spent Drilling Fluids
(US EPA SITE Demonsration Program)
US EPA's Superfund Innovative Technology Evaluation (SITE) program
is dedicated to advancing the development, evaluation, and implementation
of innovative treatment technologies applicable to hazardous wastes and
waste sites. Dehydro-Tech Corporation (now Biotherm, LLC) was selected
by the US EPA in 1990 to participate in the SITE, program and a Biotherm
Process pilot plant demonstration was conducted at the US EPA research
facility in Edison, New Jersey in August 1991, using drilling fluid waste
from the PAB Oil and Chemical Services (PAB Oil) Superfund Site in
Abbeville, Louisiana. Drilling fluid waste, a combination of fine bentonite
clay, water and oil is very similar to refinery sludges and the technical/engi-
neering results of this demonstration can be readily extended for processing
refinery and other waste streams in a commercial facility. The Applications
Analysis Report (AAR) and Technology Evaluation Report (TER) written by
the US EPA for the demonstration program are available from Biotherm,
LLC or the US EPA (US EPA 1992a; US EPA 1992f).
13.39
-------
Case Histories
'* V rflllll :! I; ill
'Hi!:
hi iiiiiii in
ill !
illlliT1
'II ill
I'll
jl
performed in a mobile pilot plant having a pro-
pe:iig capacity of; about 45.4 kg/hr (100 Ib/hr) feed (about 13.6 kg/hr [30
Ib/hr] soh'ds) installed on a 14.6 m (48 ft) trailer. In commercial units, the
Biotherrn Process is normally operated on a continuous basis. However,
becauseof equipment "limitations', "tfie" SITE demonstration was done batch-
wise on a total of 294.8 kg (650 Ib) of feed in two runs as described below:
. dehydration was done batch-wise in a single effect evaporation
operation at about 121ฐC (250ฐF) and 55.9-58.4 cm (22-23 in.)
,''''i'lili |l' .t ;,|i !||,,! i',i '|| , Ill1'1 '"ill 4 lh l'i ' "I'llh'il II1'1 '! '"I.1 hnli'i"!1 'II111 Mr I! "'Mil n<'' '''ill!'ป,|!,': :l' " I h, "P<: <
-------
Chapter 13
proportional increase in the absolute value of the metals content in the solids
and TCLP extract may be expected due to volume reduction through the
process. There is no evidence, however, that actual teachability of metals is
increased by the process.
Table 13.13
Biotherm Process Analytical Results After Three Pilot Plant Extraction Steps
on Spent Drilling Fluids (US EPA SITE Demonstration Program)
Component
Feed
Product
Solids
%Removal,
Solids Basis
Comments
Test Run 1
Water (% by weight)
Solids (% by weight)
Solvent (% by weight)
Indigenous Oil (% by weight)
TPH (% by weight)
Indigenous TPH (% by
weight)
Phenol
Phenanthrene
2-Methylnaphthalene
Isophorone
Bis(2-EH)phthalate
Di-n-octylphthalate
21.8
514
MA
175
14.7
14.7
< 100 ppm
16ppm
< 26 ppm
< 50 ppm
< 50 ppm
< 50 ppm
<0.1
96.6
0.9
1.4
0.8
<0.1
< 0.7 ppm
0.3 ppm
< 0.7 ppm
< 0.4 ppm
0.6 ppm
< 0.3 ppm
_
N\
95.8
972
99.99+
>99
99.0
>98
>99
>99
>99
Compositions
not normalized
Total solids
product passed
all TCLP tests
Test Run 2
Water (% by weight) 34.8 <0.1
Solids (% by weight) 52.4 98.3
Solvent (% by weight) N\ 1.0
Indigenous Oil (% by weight) 7.2 0.9
TPH (% by weight) 8.9 0.7
.Indigenous TPH (% by 8.9 <0.1
weight)
Phenanthrene 8.1 ppm < 1.7 ppm
2-Methylnaphthalene 49 ppm 2.3 ppm
Naphthalene < 28 ppm 1.0 ppm
Bis(2-EH)phthalate < 50 ppm 1.4 ppm
Di-n-octylphthalate < 50 ppm U
MA.
93.7
96.1
99.99+
>90
>97
>98
>98
>99
Compositions
not normalized
Total solids
product passed
all TCLP tests
TPH Total Petroleum Hydrocarbons (US EPA Procedure 418.1)
Indigenous TPH Total TPH less TPH contributed by residual "food-grade" solvent
U Undetected, % removals based on minimum detection limits
SITE Superfund Innovative Technology Evaluation program
TCLP Toxicity Characteristic Leaching Procedure (40 CFR, Part 261)
13.41
-------
Case Histories
llEilll|lil i1 IJJVli'liriiJI i1: ; '" 1IHI ' II lll'illiil'llilliiil:! Ill II
I|BP1|1IH ! " iM Ml i |j! ' i; ii,i[ i, IP" I ,!!, !'| ',; III llr :|IIIIIM
!i:i^ I ;.> liiiiN Ci.t'i !>'' I
! ! -If til'' rK, W;f:;""!' W i: i II ii
Table 13.14
Biotherm Process Product Water Quality from Spent
Drilling Fluids (US EPA SITE Demonstration Program)
"* "; ' ' Test Run 1
Solvent, (% by weight)
TPH (wppm)
Suspended
Solids (mg/L)
BQPS (mg/L)
COD (mg/L)
pH
Metals
' ' :"" ' =:; :::
Test Run 2
0.90 ' " 0.10 ;: :
1,442
82.3
333
703
16 " "'" '" " 12.7 =' " """
1,193
457
Trace
394.7
6.82
Trace
I I III
111 11(11111 111 III I 111111 illIllllll
III (I 11 Illllll III
i i |l|| III |i| i HI I 1111! II |"| Illllll I II 11 Illllll II11 I L II I I 111 I I illlillll l Id
The average ultimate particle size analysis of 12 microns and average
agglomerated particle size of 73 microns from the Biotherm Process on the
PAD Oil Site material reveals that the process can treat solids having smaller
particle sizes tnaii those'feeing"h'andTecl"'b"ycblwenfioriaf SQ{\ washing tech-
niques. Considered as ultimate or agglomerated particles the sizes are below
or close to the 63 micron average below which the US EPA has found soil
washing to be difficult (US EPA 19900).
The centrifuge centrate of solvent containing indigenous oil was a dark liq-
uid with a strong odor indicative of'm~ehea^Tiy3rocaYbon' (crude oil) source of
the indigenous oil. Although not done in the demonstration, as part of a com-
mercial process the centrate can be easily split by fractional distillation into its
indigenous oil and solvent components allowing cost-effective recycling of the
recovered solvent and disposal of the indigenous oil.
The condensed water product was a clear liquid with low suspended sol-
ids and low biological oxygen demand (BOD). Specific analyses are given
in Table 13.14. The characteristics of me'^^^^^^Q^^JQ^
lute municipal wastewater and complied with the Organic Chemical, Plas-
tics, and Synthetic Fibers industrial category discharge, limits with respect to
metals and organics concentrations.
13.42
-------
Chapter 13
Biotherm Process Remediation of F'CB Contaminated Soil
An additional application of the Biotherm Process is for the extraction of
PCB 's (and/or other trace hazardous compounds) from contaminated soils,
sediments, etc. Table 13.15 presents laboratory analytical data indicating
greater than 99.95% PCB removal from a soil by first concurrently drying and
solvent extracting followed by two solvent extractions using S-140 solvent at
ratios of 6/1 solvent to solids (Pedersen 1991). These data partially confirm
previous findings that the combination of water removal and solvent extraction
via the Biotherm Process is more effective for PCB removal than solvent
extaction of a water-wet soil. Results of other workers shown in Table 13.16
indicate that PCB extraction is particularly difficult in the presence of water.
Table 13.15
Biotherm Process Analytical Results After Three
Extraction Steps on PCB Contaminated Soil
Comments
Component Feed Product Solid's (Removals reported on solids basis)
Water (% by weight)
Solids (% by weight)
Oil (% by weight)
Aroclor 1260
(PCB)(ppb)
'
4 < 0. 1
B 99.0
28 0.8
2,000 < 1
-
. -
99.8% Removal
99.95+% Removal
Biotherm Process Economics
Table 13.17 presents some typical comparative economics when treating a
refinery K-waste (e.g., K-051 API Separator Sludge) via the Biotherm Pro-
cess and illustrates the value of feed component separation and volume re-
duction which is achieved by the process. In this case it is assumed that
4,536 tonne/yr (5,000 ton/yr) of waste, concentrated by onstream centrifug-
ing or belt pressing from a typical 100,000 bbl/day oil refinery is treated at
the refinery site. The on-site investment for l:he facility is about $1.3 million
13.43
-------
I'Sifc jiiiiin " ' iiflyiinii!1
Case Histories
'.I- ''111! 3(11'
iiili'i'illi1 , i I ! . . ,; , III III
'If illKlli!'''1! ,9! I
li, llllllillll' peed" Sludge 100% Solids
Solvent Kerosene
":"; :l:: '"Initial " M,26S
After 4 Extractions 251
Source: Blank, Rugg, and Steiner 1989
Soil Moisture 40% Moisture
" "~ '' Initial 28
After 1 Extraction 25
After 2 Extractions 25
,
Source: Massey and Darian 1989
-Ei Table 13.16
Extraction of PCB's from Contaminated Soil
58% Solids/42% Water
KWnsene Acetone
PCB Concentration on Solids (ppm)
36,268 33,641
" "" ' ' "' ง0,873 11
10% Moisture Dry Soil
PCB Concentration (ppm)
:': "" 28 " " '"Jl":" " 50
18 ! 10
175 0
,: | , !
Table 13.17 assumes a credit for recovery of the indigenous oil of $l5/bbl
which lowers the net operating cost of the Biotherm Process Unit to $82 to
$88/tonne ($75 to $80/ton) of feed. The present alternative for hazardous K-
Waste disposal as practiced by many refineries is to burn the wet sludge in a
cemejitkilnorincineratoratacost of $549 to$l,648/tonne ($500 to $1 fnn
toh)I f hus'i"Sie"giQ^g^'p^Qcess has a major economic advantage.
13.44
-------
Chapter 13
Table 13.17
Biotherm Process Economic Estimates Refinery K-Wastes
Cost Component
Operating and Maintenance Costs:
Electricity, 46 kW
Steam, 1.2 klb/hr
Cooling Water, 130 gal/min
Operators, I/shift
Maintenance
Indigenous Oil Recovery
Capital Recovery
Biotherm Process Cost (including Indigenous Oil Recovery)
Disposal Costs:
Water Disposal; 0.6 ton/feed ton, 150 gal
Solids in Nonhazardous Landfill; 0.1 ton/feed ton
Recovered Oil Credit; 0.3 ton, 1.8 bbl
Total Processing/Recovery Costs
Disposal as Hazardous Waste in Cement Kiln/Incinerator
Savings for Biotherm Processing
Unit Cost
$0.06/kWhr
$450/klb
$ 0.50/kgaE
$35 k/man-3'r
3% Inv/yr
Estimate
12% Inv/yr
-
$15/kgal
$100/ton
($15/bbl)
-
$500/ton
-
Waste Feed
($/ton )
4
8
6
32
8
3
31
92
2
10
(27)
77
500
>400
Process/Economic Bases:
Feed:
Water 3,000 tons/yr 60% (by weight)
Solids 500 10
Indigenous Oil 1.500 2Q
Total 5,000 tons/yr 100% (by weight)
(0.7tons/hr)
Estimated On-site Facility Investment (1993) $1.3 million (US)
It should be noted that if, because of the presence of undesirable compo-
nents, the recovered indigenous oil had to be disposed of as hazardous waste at
$549/tonne ($500/ton)($165/tonne [$150/ton] of feed), the total processing/
recovery costs would be about $275/tonne ($250/ton), still a savings of about
$275/tonne ($250/ton) of feed. Similar reasoning would prevail if the separated
solids were still hazardous and required disposal as a hazardoTas waste at $5497
tonne ($500/ton) solids or the equivalent of only $55/tonne ($50/ton) of feed.
Again, a substantial savings over disposal of the total feed as hazardous waste.
13.45
-------
'Ill
IPlll'l',111!,
1!
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nil iiiini i inn n i mm in n i inn i n i in i 1 1 inn i i inn 11* 1 1 inn linn mi n iiiiiiiiiiiiiiiinniiiiiii hi mini nn nn
p',11 mi "in ' i " "'ii i'iii',,i,i''ii i hi
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Case Histories
I i+lfiiUJIl""!!1 '. ' ''I ' jflililliWI:'!!!,',,1' , ;i 'i,!l, * ซ '!': I'1' Til III
In applications where only drying is done with the use of a heavy "sol-
vent", Biotherm Processing costs will be one half to two thirds of those
when full solvent extraction and desolventizing is performed.
Table 13.18 presents Biotherm Process economics developed according to
the guidelines furnished by the US EPA for the SITE demonstration for
remediating 20,865 tonne (23,000 ton) of drilling fluid wastes having the
properties of the PAB Oil Site materials. Although the total technology
based costs of $110 to $182/tonne ($100 to $200/ton) of feed for the
Biotherm Process is attractive relative to alternative processes, larger plants
result in even more economical operations. It is obvious from Table 13.18
mat the most important factor in ^Controllableoperating costs is operating
labor. This portion of the total cost drops at higher unit capacities because it
requires about the same number of operators to run larger units.
As sh'own in fable 13.18, a significant Biotherm Process advantage is
that it produces residuals which may be disposed of very economically.
Using the economic bases furnished by the US EPA, it is assumed that
the clean product solids are backfilled at their original location at
$16.50/tohne ($15/ton); alternately they could be sent to a sanitary land-
fill at $49.50/tonne ($45/ton). As noted previously, removal of oil and
water from the solids also gives a product which is more'readily stabi-
lized if remaining components such as metals require it Recovered
water is treated in a POTW at $2.00/kgal.
In Table 13.18 it is assumed that since the recovered indigenous oil was
originally a product of petroleum drilling production, it may be recycled to
an oil refinery at an approximate crude oil value of $20.00/bbl. As a result,
there is a credit to this Biotherm Process application of over $33/tonne ($307
ton) of feed for the recovered indigenous oil. It must be noted that because it
came from a Superfund site, the suggested US EPA basis (US EPA 1992a;
I*1 ii ' iJiliilB ' ' ! .' '1 ..< ''Wi'jHif' >1i,W3!',,.:Jiii Rปv,, & ซ; ,. j, 3 ซป yr^-^-- _M : :ซ...*:,ซ, at
IE,:1; " ซ ; ,ซ,ซ lyg ,.(., -j^. t
j j-tiiiiiii .,,1 liiiii
' i:; iinB ' fill
IV: 'I,': !' '''It:' Mil
l,f/"X iy^^fil JLWJ. U-UL/VyUMJ- *-ป* *wvปw.ซ.vw -..*ป-.Q -
,;':,ซ! fjt''Vs^"* /atift?'nSffJtrmn? rfci OOO/tonl oil") or aoDroxi-
ifiijlt^hvii Si - <"' jtHf * ; flr.;.ii;,.ii j'mSe: min - -' i',; -$4V5y Per ** gal OJUm (.aDOUt q> 1 ,Uyy/lOnne LO>1,UUU/IU11J uiv U1 apprwAi
' ' '" ' ' ' ;l " ""'''' '" :'i;""'"'":"! "l " ' ('"IJ!"1 * - $2647tbnne ($246/ton) of feed versus a credit of about $33/tonne
mi: iimiii'uiiniiiiiimiimn ( i
^a^, <,^,~ ^~.
($งd7ton) of feed shown in Table 13.18. While disposal as hazardous waste
rnay be appropriate in^ some cases, due to regulatory constraints and/or
where analyses indicate the presence of sufficient contamination to require
burning, in this instance incineration seems unnecessary.
III us Hi!!!" f 'i'1 ,,j. !, 'j'i'1:!*;, ' ||
13.46
-------
Chapter 13
Table 13.18
Biotherm Process Economic Estimates Spent Drilling Fluids
Basis: 23,000 ton Remediated; 31% Water, 17% Indigenous Oil. 52% Solids
Feed Rate (ton/hr)
Years @ 70% On-Stream
Investment ($ in millions)
1.4
,Z7
130
1.9
ZO
IX
is
15
1.75
Technology Based Costs ($/ton feed)
Capital Amortization
Startup/Shutdown
Labor
Solvent Makeup
Utilities
Maintenance
Total Technology Based
21.50
820
105.50
8.90
15.30
4.50
16:1.90
18.70
8.20
78.50
8.90
15.30
3.90
133.50
16.20
820
59.00
8.90
15.30
3.40
111.00
Site Specific Costs ($/ton feed)
Site Prep/Excavation
Residuals Treatment
Solids and Water
Recovered Oil Credit
Total Site Specific
Grand Total (S/ton feed)
54.00
130
(31.20)
3o>io
194.00
40.20
730
(31.20)
16.30
149.80
30.20
730
(31.20)
630
117.30
Economic Bases (except as noted per US EPA):
Equipment Amortization: 7%/yr interest, 10 year life
Startup/Shutdown Costs: $125k startup; $63k shutdown
Labor: 1 Feed and 2 System Operators Q $40/hr. 3 shifts/day; 1 mechanic & $40/hr. 1 shift/day
0.5 Supervisor @ $60/hr, 1 shift/day
Solvent: 5.93 gal/ton of feed & $1.50/gal
Utilities:
Cooling Water 8.8 kgal/ton of feed @ $0.05/kgal
Fuel (steam) 1.47 MBtu/ton of feed 6 $5.00/MBtu
Electricity 28.6 kWhr/ton of feed G $0.06/kWhr
Nitrogen 1.16 kscfAon of feed ฎ$5.00/kscf
Maintenance 3% Investment/yr
Site Prep/Excavation: $75.55/hr operation
Solids Disposal: 0.48 ton/ton of feed 6 $15.00/ton
Water Disposal: 72.2 gal/ton of feed ฉ $2.00/kgal
Indigenous Oil Credit: 1.56 bbl/ton of feed 9 $20.00/bbl (per Biotherm)
13.47
-------
1 III
Case Histories
if I"
Si ivy i ,"
llli""" . "i ' If!
in
Caution must be exercised in comparing the continuous operation of the
refinery waste case of Table 13.17 (0.7 ton feed/hr) with the relatively short
remediation period (1.5-2.7 years) of the drilling fluid case of Table 13 18
4_2 5 ton feed/hr). Although the higher capacity divisor of the remedia-
tion case Is an advantage, it is offset by higher labor costs since it must be
more fully manned at an independent site rather than operated within a refin-
ery complex. Capital recovery concents"'mist also be considered for a con-
tinuing treatment process in a refinery where a "feed" supply is assured for a
number of years versus the relatively short period of operation of a remedia-
tion project where the investment capital must be recovered in less time for
on! project or over a few assured projects. Finally, feed compositions and
product quality requirements will determine both investment and operating
costs for specific projects. Sufficient economic details are given in both
tables so that the reader may develop very preliminary screening economics
for comparable potential projects.
No eco^ soil remediation cases since they
would be very sle-specific, but it is predicted that treatment costs would be
in the $110 to $182/tonne ($100 to $200/ton) of feed range like those for the
drilling fluid cases^ Costs of treating/destroying the concentrated PCB prod-
uct stream are not included.
Conclusions '" '
The technology flexible, commercially proven, proprietary Biotherm
Process is a combination of dehydration and solvent extraction treatment
technologies which has wide applicability for separating hydrocarbon sol-
vent-soluble hazardous organic contaminants (indigenous oil) from sludges,
soils and industrial wastes. Materials which may be treated include refinery
K- and F- wastes which are regulated under RCRA, contaminated soils and
sediments which must be remediated under Superfund, as well as other haz-
ardous and nonhazardous solids7on/water"mixtures. As a result of this treat-
ment, the products from a Biotherm Process facility are:
(1) Clean, dry, hydrocarbon-free solids which meet RCRA BDAT
and other regulatory requirements and are suitable for disposal in
II .; :>'' !?'/ ฐ-MII . -lisj - " ..*ป-. .. ". '.* ii
nonhazardous; landfills;
(2) Water which is treatable in an industrial or POTW wastewater
treatment facility;
13.48
I ill 'lllii'iliii I Ill Ill I
-------
Chapter 13
(3) Extracted indigenous oil containing contaminants which may be
recycled/reused for credit or disposed of at less cost than the
original waste feed.
While Biotherm Process economics are feed and product quality sensitive
and site-specific, typical operating costs are usually between $55 and $110
per feed tonne ($50 and $100 per feed ton) for a refinery type waste and
$110 and $182 per feed tonne ($100 and $200 per feed ton) for soil
remediation; both are very competitive with other treatment techniques such
as incineration which may be $549 to $l,648:/tonne ($500 to $l,500/ton) for
hazardous waste.
References
1. Elliot, J.D. 1992. Maximize distillate light products. Hydrocar-
bon Processing. January: 75-84.
2. US EPA. 1992a. The Carver-Greenfield Process, Dehydro-Tech
Corporation, Applications Analysis Report. EPA/540/AR-92/
002. Washington, DC: US EPA. August.
3. US EPA. 1992f. Technology Evaluation Report: The Carver
Greenfield Process, Dehydro-Tech Corporation. NTIS Docu-
ment Order No. PB92-217462AS. Washington, DC: US EPA.
August
4. US EPA. 1990c. Engineering Bulletin: Soil Washing. EPA/540/
2-090/017. US EPA Risk Reduction Engineering Laboratory,
Cincinnati, OH. September.
5. Pedersen, J.W. 1991. Use of the Carver-Greenfield Process for
remediating petroleum contaminated soil. Master's Thesis. The
Cooper Union for the Advancement of Science and Art. April 15.
6. Blank, Z., B. Rugg, andW. Steiner. 1989. LEEP-Low Energy
Extraction Process: New Technology to Decontaminate PCB-
Contaminated Sites. EPA SITE Emerging Technologies Pro-
gram. Randolph, NJ: Applied Remediation Technology, Inc.
7. Massey, MJ. and S. Daiian. 1989. ENSR process for the extractive
decontamination of soils and sludges. Paper presented at the PCB
Forum, US EPA International Conference for the Remediation of
PCB Contamination. Houston, TX. August 29-30.
13.49
-------
: . . !. , I' : Ill: I l|l| I I I II I ! Ill Illllll
Case Histories
111 lllllll ( I I illliill 111 I III I III ,:"M/!' MM" ..... "';ป ..... ,": ' !,'."': *" iC ..... ,,!,ป* ill ^lWfnit,;**Mlltr,1. ...... ii ..... I ..... iljiliJi/iyililS!;''1 ........ :':ซ:;- '.'.; if ...... ;,ii Ililllh 'III ..... it
Case 4 Resources Conservation
'^QOX^M'?.BaslcJx*r?ฐnv? *lu.d9^
,1; iiiiif1" ....... rr.it' ..... n1:*1
.1.5. T.ฎ), Grand Calumet
River, Gary, Indiana
The B;KS.T.ฎ Process is a patented solvent extraction system that uses
triethylamine at different temperatures to separate organic contaminants
from sludges, soils, arid sediments. The organics are concentrated in an oil
phase, thereby reducing the volume of wastes that require further treat-
ment. Multiple extractions are conducted at predetermined process con-
ditions and are followed by>olvenFrecovefy,'" oil polishing, solids dry-
ing, and water stripping.
The use of triethylamine as the extracting agent distinguishes B.E.S.T.ฎ
from other solvent extraction and soil washing technologies. Triethylamine
has a property known as inverse miscibility. At temperatures below 16ฐC
iijj ;;:i: I-:::;'; (60ฐF), triethyiamine is miscible with water; above 16ฐC (60ฐF), triethy-
lamine is only slightly miscible with water. Therefore, at temperatures be-
low 16ฐC (60ฐF), solids can be dewatered and organic contaminants can be
extracted simultaneously. This process is referred to as a cold extraction.^
Following cold extractions, &e exttacBon teinperafiitS is raised above 16ฐC
(60ฐF), and any remaining brgariic contaminants are removed. These warm
and hot extractions are usually conducted at temperatures ranging between
- 38 to 77ฐc (100 to170"F) The organic contaminants initially present in the
sludge or soil are concentrated in the oil fraction; additional treatment (e.g.,
incineration) is required to destroy or immobilize these contaminants.
1 "ill! ii" 111 " " i , , V i,T|^s1Summary::wis''de^ioped by US ERA's Risk'induction Engineering
Laboratory, Cincinnati, Ohio, to announce key findings of a SITE Program
demonstration, which is fully documented in two separate reports.
The SITE Program was established in 1986 to promote the development
and use of innovative technologies to remediate Superfund sites. One com-
ponent of the SITE Program is the Q^QnstratibnPiogram; through which
US EPA evaluates field or pilot-scale technologies that can be scaled up for
commercial use ."'"The 'main''objective' of the demonstration is to develop per-
formancel engineering, and cost information for these technologies.
iin 111 i in i iiiii
III I I i III, il11 ill i i .v .*>>/..:'! .!i!|1ซ'ia*-?VU;
.,,: r;r'1i(aป;'f . . _ ..
-' MM ; ,', " : ...... : "; ". ~T ..... *" ' "" : ' **;': I ' ' . " : " ""' " "' :: ' : : " " ' ' " ' " ":;"!:: ;;:l!i : '"""' ..... ! ......... lir '. ,
-------
Chapter 13
This Technology Demonstration Summary highlights the results of an
evaluation of the effectiveness of the B.E.S.T.ฎ Process to remove PAHs,
PCBs, and oil and grease (O&G) from bottom sediments collected from the
OCR in Gary, Indiana. Figure 13.12 shows the general locations of the
demonstration test area, test sediment collection points in the GCR, and
major regional features. Sample locations were chosen to obtain two differ-
ent sediment types, Sediment A and Sediment B. Sediment A contained
high concentrations of metals and low concentrations of organic compounds,
relative to Sediment B. Sediment B, collected! upstream from Sediment A,
contained high concentrations or organic contaminants such as PAHs, PCBs,
and O&G.
Figure 13.12
Regional Location Map
Chicago
N
A
Gary, IN
13.51
-------
Case Histories
IIIIIII'IIIIIIIIIIIU,!,. ,11(1"! ("i ,11
I1!''!!!:!1"1""! f'lii
i| "ill,1'1'!!1 i>t I <; ifpini',
L '"I,11 1 L lllilliilii'.
ITU;
111!!"1"
" ,i 'li'Mii initii
, ,;" ..... 'ifji ...... !'!!l:fl|||l
i,:'1; ,,11!;,; ..... rw" fl
IIF'iUi'll! II1 MI! ' "Ii
1,1 f lEIIHii ! i..'.| "' : "
PI I ' MiLUll1 II1!1 LF lI'iMRIJ,
Prior to the demonstration testing, both sediment types were prescreened
JQ separate oversize materials and were thoroughly homogenized (mixed).
r^^-jfcencfijgcale treatability tests were then conducted on each of the
sediment types. These tests were performed by RCC to determine initial
operating conditions, such as the number of extraction cycles, to be used in
rr^fl^i^g^ A flowchart of the experimental design used to guide the
B.E.S.T.ฎ evaluation is shown sis Figure 13.13.
:. "iiini! iii;:i" : i
ill, (illit !']': 1 U !!l!"i| r 1,1,1. IF l:>> II i III
HI , 1 ii
' .u-
llili i 111 il
a ....... it: m
,,,i ,, ,1,
Figure 13.13
Experimenfal Design Flow Diagram
River Sediment
Characterization Sampling
Collection of
River Test Material
Prescreening and
Homogenization
of Test Material
Bench-Scale
Treatability Tests
Demonstration
Tests
. *
, ,,
: j;!
'-:': The ...... demonstration consisted of two ..... gepSe tesls^ one for each sediment
type. Each test consisted of two phases. Phase I involved determination of the
^"Bmixm process "variables. from the results of three runs, and Phase H consisted
^two'11aMtionairiins at^ ....... Samples of ***
'Intreated sediments, product roll^'^oductwibi^'aiui product' oil were col-
lected during each of the five runs (Phases I and II). These samples were ana-
Jj^'fe total'"EAHs, PCBs, and O&G: ......... Product solids, product water, and
product oil were also analyzed for residual triethylamine solvent.
13.52
n i::ai. :,". i 11
-------
Chapter 13
Results of the demonstration showed that the process met (or exceeded) the
vendor's claims for organic contaminant removal efficiency of >96% for treat-
ing both of the test sediments. The analytical results for Sediment A indicated
that the process removed greater than 98% of the O&G, greater than 99% of the
PCBs, and 96% of the PAHs. The residual solvent in the product solids and
product water generated from Sediment A was 45 mg/kg and less than 2 mg/L,
respectively. A final oil product was not generated for Sediment A because of a
lack of oil (less than 1%) in Sediment A feed. The analytical results for Sedi-
ment B indicated that the process removed greater than 98% of the O&G and
greater than 99% of the PCBs and PAHs. The: residual solvent in the product
solids, product water, and product oil generated from Sediment B was 103 mg/
kg, less than 1 mg/L, and 733 mg/kg, respectively.
Process Description
The B.E.S.T.ฎ pilot-scale system is designed to separate organic contami-
nants from soils, sludges, and sediments, thereby reducing the volume of
hazardous waste that must be treated. Triethylamine is used as the extracting
agent because it exhibits several beneficial characteristics. These character-
istics include:
a high vapor pressure (therefore the solvent can be easily recov-
ered from the extract of oil, water, and solvent through simple
stream stripping);
formation of a low-boiling azeotrope with water (therefore the
solvent can be recovered from the extraction to very low residual
levels, typically less than 100 mg/L);
a heat of vaporization one-seventh that of water (therefore, sol-
vent can be recovered from the treated solids by simple heat with
a very low energy input); and
alkalinity (pH = 10)(therefore, some heavy metals can be con-
verted to metal hydroxides, whicli can precipitate and exit the
process with the treated solids).
The generalized B.E.S.T.ฎ solvent extraction process is shown in Figure
13.14. Contaminated materials are initially screened to less than 1/2-in.
diameter (1/8-in. for this demonstration). The screened material is added to
a refrigerated Premix Tank along with a predetermined volume of 50% so-
dium hydroxide. The Premix Tank is sealed, purged with nitrogen, and then
-------
a "I 1 !'TI
I !!ซ! I !i Mi i
i : BJ-.L ซr ^ fc i ;?ai it ^ฅ I r "! - l= =
'
= j ^ w- -= iซi 5=
|j| i J p| ; ii ;!'
i 3;y: i
^ =JM = 3S;_. 11 ;SH= , s b p .an = I la 111 a 1= =
r I ,>!? ซ !ซ , u Jiap i i *J ,-ป;
;ป;ปซ ; ;; ag- i 5;: 5:,.
; !
("! : f ;" : ;| i , P;c^1raซa. 4 ซ L -: :; i ,:=, |f -i ! -;- - .=f " ; i" ? ' !
ii= = -- . j = i - *= t- - - * =: -i, -=-. .=_-'.--;==_ ^ ,- ~^-- m _=3
I' -'= ! / -!: H^.ฃl;:^ ;-':- '* /^ !,- -V .. .-Jiป-= :
!ซ: .M' s ; ^: ;::ซ^?:-*i:, ;^:: r^ ;
| jll! I i! ji! '
111 i !N !li i
H P
I! I IW Mil
":-*:;: ~ "gf , '
;^JK^lll
1 j' pi
Figure 13.14
Generalized Diagram of the RCC B.E.S.T.ฎ Solvent Extraction Process
8
(D
sr
(D
co
-2
Primary Extraction/
Dewatering
SoU>
Secondary Extraction/
Solids Drying
Solvent Storage I Solvent Separation I Solvent Recovery
111
inter
r*
vent
anter
N
; I
)
t\SL/
i
IfTi
iyy
fc
A
V
^-k
Solvent
Evaporator
Oil Product
Water
Stripper
Water Product
-------
Chapter 13
filled with chilled triethylamine solvent. The chilled mixture is agitated and
allowed to settle. The resulting solution and this cold extraction consists of a
mixture of solvated oil, water, and solvent. The mixture is decanted from the
solids and centrifuged, and the solvent and water are separated out of the
mixture by distillation.
The cold extractions are repeated as additional feed is added to the
Premix Tank to accumulate enough solids to perform subsequent extraction
cycles. Solids with high moisture contents may require more than one cold
extraction. During this demonstration, Sediment A (containing 41% mois-
ture) required two cold extractions.
Once a sufficient volume of moisture-free solids is accumulated, it is
transferred to the steam-jacketed Extractor/Dryer. Warm triethylamine is
then added to the solids. This mixture is heated, agitated, settled, and de-
canted. The warm and hot extractions separate the organics not removed
during the initial cold extractions. Three products are derived from the total
process: product solids, product water, and concentrated oil containing the
organic contaminants.
The pilot plant used for this demonstration is a self-contained mobile unit
that allows on-site testing to be performed at a pilot-scale. It consists of two
portable skids that are mounted on a low boy trailer 2.4 m by 13.7 m (8 ft by
45 ft) on which the unit is transported. The process skid 6.1 m by 2.4 m (20
ft by 8 ft) has two levels and contains the majority of the B.E.S.T.ฎ process
equipment including the Premix Tank, the Extractor/Dryer, the Solvent
Evaporator, the Centrifuge, storage tanks, pumps, and heat exchangers. The
second smaller utility skid 3 m by 2.4 m (10 ft by 8 ft) contains several util-
ity systems to support the operation of the process skid, including a refrig-
eration unit used to cool the solvent. Power requirements for the pilot plant
are 480 V, three-phase power at 225 amp, which is accessed from a main
power source (i.e., electrical drop) by an electrical distribution panel sup-
plied by RCC. A support trailer accompanies the pilot plant, transporting ancil-
lary equipment and providing a storage and working facility during testing.
Test Program
The primary objective of this SITE demonstration was to evaluate the
effectiveness of the B.E.S.T.ฎ solvent extraction technology on two test sedi-
ments having different contaminants or contrasting concentration levels of
13.55
-------
ill I I II III III III III III ill 11
i i i i in nil
Case Histories
n nnii
the same contaminants. Therefore, the sediments treated were collected at
two different transect locations along the east branch of the OCR (see Figure
13.12). Sediments collected and homogenized from Transect 28 were desig-
nated Sediment A, and sediments collected and homogenized from Transect
6 were designated Sediment B. The transect locations were located approxi-
mately 3.22 km (2 mil) apart. The Sediment A (Transect 28) location was
located slightly downstream of an oil-skimmed settling lagoon, which re-
ceives wastewater from primary bar plat mills and basic oxygen process
(BOP) stiops.' Sediment B (Transect 6) was located slightly downstream
from the djscharge of a coke plant. Sediment A consisted of high levels of
metals and low"levels of organic"contemfnants relative to Sediment B. Sedi-
ment B was composed of high levels of organic contaminants and lower
levels of metals.
Prior to the demonstration, each of the two sediment types was
prescreene"d, thoroughly homogenized, and subjected to bench-scale treat-
ability testing. These tests, which were conducted by RCC, provided initial
operating conditions. Critical measurements were identified with the aid of
sedimenrcharactenzalon analyses". The critical parameters selected for the
demonstration tests were:
","-"li; *:''l!::FiAHs'"and PCBs in all solid and liquid process streams;"
'" o&G in'tneTeet'niateriai, treated solids, and water (o&Gt was
>' ' ,: i', i.: !' ,;! Him ill!" '-'"Pซ, n"' Ji":'". ซ HI-PHP! '' "w, :;n.;j:.i n mui n| "i ;,ป,, '',;,< j :j ^iii ปi. ||ป"!; | air i; iiiyiBiLii i, iiiniiii1 ii|r; HP: v\\ iii a r 1,1 ,,1,1 i|iini|||! ih cm \<& ini'n <.ii||i;" 'iii'^ii11 ' ,M " i n i; ซP ,:
-------
Chapter 13
variables for each test sediment. These variables included number of extrac-
tion cycles, mixing times, and extraction temperature. Three sets of condi-
tions, determined by RGC, were tested. Phase II consisted of two additional
runs at optimum conditions determined in Phase I. This resulted in a total of
three runs at optimum conditions for each sediment type. Tables 13.19 and
13.20 present the actual sequence of extraction cycles conducted during the
demonstration for Sediments A and B, respectively.
Table 13,19
Extraction Sequence Used for Sediment A
Extraction Temperature ("F)
Extraction
Cycle
1
2
3
4
5
6
7
Run 1
cold (62)
warm (106)
warm (95)
warm (95)
warm (103)
hot (170)
-
The three optimum runs are Runs 3,
Phase I
Run 2
cold (50)
cold (40)
cold (38)
warm (98)
warm (125)
hot (160)
hot (160)
4, and 5.
Run 3
cold (53)
cold (45)
warm (100)
hot (155)
hot (166)
hot (166)
hot (166)
Phase H
Run 4
cold (48)
cold (42)
warm (110)
hot (155)
hot (163)
hot (164)
hot (164)
Run 5
cold (52)
cold (46)
warm (97)
hot (152)
hot (167)
hot (160)
hot (160)
Samples were collected and analyzed for each process stream specified in
Table 13.21. PAHs, PCBs, and O&G were critical analyses for all media
except vent gas. These contaminants were known to be in both sediment
types and were the primary constituents targeted for removal using the
B.E.S.T.ฎ Process. Triethylamine was targeted for analysis in the product
streams and vent gas emissions because of its potential as a process residual.
Moisture content and TCLP were considered critical because of the original
characteristics of the sediments (high moisiture and metals contents).
13.57
-------
lllllllll lllllllll II lllllllll lllllllll III lllllllll lllllllll 1 lllllllll 1 lllllllll IIIII 111 II II III IIIII 11 lllllllll 11 11 II III lllllllll 1111 III
11 111 IIIII III III 1 11 1 IIIII 1
III I'll II II 1 1 11 ll 1 III 1 111
Case Histories
I" ; i r ; i ' : , ;.: " ,: "i , ;;;: .: , ,:. :.'. : :.
Table 13.20
Extraction Sequence Used for Sedi
Extraction Temperature (*F)
Extraction Phase I
Cycle Runl Run 2 Run 3
jajjmi ;:f,":|| ;i|p; ' ,i|,i,' ,,, ..:;:;y ^ftj.^ '. IAI ,. coid(49) coid(28) coid(32)
1A2 cold (47) cold (42) cold (40)
ง. ::' , '|,:; 1 1 : ;/ |||; | : ; j j^j1; ; . . ^ ( ' | coid ob '^ ty
1B1 cold (41) cold (39) cold (29)
1B2 cold (53) cold (47) cold (38)
1B3 cold (52) cold (36) cold (46)
2 hot (145) hot (152) hot (151)
3 hot (152) hot(!>5,7> I1?'. 1125
4 hot (161) hot (150) " '"'hot'Tlsi)"
5 hot (148) hot (152) hot (151)
lllllllll IIIII lllllllll 1 III I III I II III 1 III III IIIII IIIII IIIIllllll lllllllll IIIII IIIII lllllllll
1 II II 1 III II IIIIII
nil i i ii iwiinnn in
,
i i '
ment Bฐ
1 i ,ir . , '','' .1 1,1,1 1:1,11"' ' 'i1 ' , 1 'i iiiiili vi""i''ii' T",,,,! / hi
Phase n
Run 4 Run 5
cold (28) cold (51)
cold (48) cold (41)
cold (39) cold (39)
i Mi in II 1 i,l ,1'il' - , lii'lll" ISii, - >,' 11
cold (51) cold (39)
cold (53) cold (45)
cold (46) cold (44)
hot (147) hot (146)
hot (156) hot (160)
lo't (i'70)' - , "h3t"(153) " '
hot (155) hot (154)
6 hot (157) hot (151) hot (146) hot (158). hot (152)
7 '" hot (143) "'-"' ': hot (150) ^ - - /'
The three optimum runs ant Runs 2, 4, and 5.
Because of the high mofsture content of Sediment B, both sediment and solvent were fed to the Premix Tank. The
portions of each . "we're limited so that the temperature rise of the solvent/water phase was at an acceptable limit.
"NC = not conducted
Ill U i Ji HI ii i| iiiiii in i i | '/: ':;;:ซ: '": ,i,:: < v ii i1 " ''.';. ". , &\"i;f !'.*>' wfjui-'SW niiN
iiiikiii li'l1 ' i ll I'll ' i ' : "I1 ;>'',: ",!:;;;: :-i ..t:-\,i '! :;i rwi Kiwmi '. $m
Six main process streams were sampled and analj
'zed for each of the two
tests. These process streams IncluSed u-|^a|-^ ^ea|men|s (raw fge^), prod-
uct solids, product water, product oil or oil/solvent mix, recycled solvent,
and vent emissions. Decant water collecitei from Buckets holding the feed
from one of the Sediment B batches was also sampled. Each lot of product
triethylamine was sampled prior to use.
\
Results
The following data summary is derived from this SITE demonstration:
Contaminant reductions of 96% or greater for total PAHs and
greater than 99% for total PCBs were achieved from treatment of
in iiiii ii i n
nil inn i in ii nun i i inn
(ii ii1 in "in i in
i n i i in i i i
1 II 11 1 1 , ,'",,, ; , '1 !!!' '( ,:,:,:", |,l,'l ilirl1,!*,*1,11 ,, 111,1 ;!!'! lh '' ' ,i, ,,l III,,"1 rii,1!," ,r, ,,,,:, |," , Hill1, ,, /"I;;;1 ' t , , , ' 1,11: V ' "1 iUll|, , ! .il1', , 'I, illll,'"!!,,!',,,!
1 ' 111 ' ' ^:'::'ft'^ '! W,W fc'^.ซ)}:W, !i r' W> '>?^ i\n&i^m
I Ill i i in .,.' '*'.' .i',.1*?**:'*! t!; ''l,iSS':-,";!li,.',ii :<,
II II IIIIII III 1 1 : ',, ' ,11 ' il1' '' I1 " i1 niiniJ1"1'1 , I'lliU lii'nl,1 ,"' ,'l;i:illll
11 1 Hiiiiiiiii i i i , I,. "':. ; v 'i'.1 mi!:1""!'''! ,:;:,,,Bi.:i|ii' :&^ ' "BiV'iiH i"ซ
<:,
J ' :,J'i
1! A
, ,.ซ:,. , ,,:> , ^"'.'J , ^ ,
liii1!-,1'! ป(,;), ii !!p'"ปrtiiiit> r , n it ,'':,. :'*i'fci''ii^ jiiiiii *. '^',m~i
-------
Chapter 13
bottom sediments collected from Transect 28 (Sediment A) of the
OCR. Contaminant reductions of greater than 99% for total
PAHs and greater than 99% for total PCBs were achieved from
treatment of bottom sediments collected from Transect 6 (Sedi-
ment B) of the OCR. Table 13.22 provides the percent removals
for individual PAH compounds from test sediments, as deter-
mined from averaging the three optimum runs. Table 13.23 pre-
sents the PCB removal efficiencies from test sediments for each
test run and as total optimum run averages.
O&G removal efficiencies in excess of 98% were achieved in the
treated solids generated from both sediment types, as shown in
Table 13.24.
Mass balances calculated for all materials entering and exit-
ing the process indicated that very good mass balance clo-
sures were achieved from treatment of both test sediments.
Closures of 99.3% and 99.6% were obtained for Sediments A
and B, respectively.
The products generated using the B.E.S.T.ฎ Process were consis-
tent with RCC's claims with regard to residual triethylamine
concentrations. Average triethylamine concentrations of 103 mg/
kg, less than 1 mg/L, and 733 mg/kg for solid, water, and oil
product, respectively, were generated during the treatment of
Sediment B (Transect 6). Solid and water products generated
from the treatment of Sediment A achieved average residual tri-
ethylamine concentrations of 45 mg/kg and less than 2 mg/L,
respectively. Product oil was not generated from treatment of
Sediment A because Sediment A originally contained very little
oil (less than 1%). A summary of RCC's claims, and actual tri-
ethylamine concentrations in the treated solids, product water,
and product oil are presented in Table 13.25.
Costs
Operating and equipment capital cost estimates were developed for the
proposed full-scale B.E.S.T.ฎ system. The cost estimates were based on
information provided by the vendor and on several assumptions. These as-
sumptions were based on the experiences of this demonstration and a
-------
I i
ill 1
i i
r s ซ;: li!' ?' n H
I I
1
1
1
t
It- -
fc
'=>
9
I
B
|
[j
E
t =
J
6;
I;
l:
1
1"
1
V
i
*
fc
1
i J ; : i a i , ป, :
~ S vii li!i :: | (; 1 !
ป " a ' i i ii i rr - :
1 1 in; ]!!i I, K ii ii
- : ; ; '
:r
i ,. _ ;
2 ^ ^ ป = : ^ . / =^
"- V ij ] 5 i >: :'
~= = ' - r ^ = ! TV
.=.;(._
- ^ ' .= - 5 !. E-- !V
. .- s :
*
Y
== 1 -, ~f! \==_= = " J - = = ,.--,-"
fc MB! i ;ii, i ; I I :ป; = - m
1 ;nsi i U; ! I i I J it! 1
:;'" ' .- ;. : :s. : ซ
T - ! , ; ! , i
-: - = l !
^: = _ A : ^ :; r I _ = L L : . ^ ! _,!:__ \
'4' M? ' i - ;; - r / i { : , - v , - :
ii ^ "^=: * = =. = ? J1 ^ , 1 !i = ฐ . ;J J
, '_ i ; ; , , I - -
; fc ซ: !; ; >! - '- ! i . ^^ :. .
.'. r' MT " : ;. : " " . -. - * '..'. "." ;
Table 13.21
Summary of Analyses Conducted for the RCC B.E.S.T.ฎ SITE Demonstration
_
Parameter
V-
''i. Critical
'j PAHsป
L PCBs
Oil and Grease
ii Moistureb
ป Triethylamine
^
TCLP Metalsc
I Non-critical
* Total Suspended Solids
Proximate/Ultimate
| Total Metalsd
Treated
Untreated Sediment Water Phase Decant Water Oil Phase Intermediate Solvent Feed
Sediment (Product (Product (From Raw (Product Solvent/Oil and Recycled
(Raw Feed) Solids) Water) Feed) Oil) Mixture Solvent Vent Gas
-
AAAAAAA
A A A A A A A
A A A A
A A A
A A A A
A A
A A A
A A A
A A A A
O
Q
CO
O
:c
<75*
g
of
in
J
-_
-
I
=
=
t
=
: |
!
"
= =
I
i
-
=
-:
i
Total Recoverable Petroleum
Hydrocarbons
-------
Volatile Solids
Total Cyanide
Reactive Cyanide
Reactive Sulfide
Particle Size
Total Phosphorus
pH
Total Dissolved Solids
Total Organic Carbon/Total
Inorganic Carbon
Biochemical Oxygen
Demand
Conductivity
Special Studies
Biodegradation
A
A
A
A
A
A
A
A
A
A
A
A
A
A
" ~~~ A
A
A
A
A
A A
A
A
A
_ _ _ _ _ __^_ . _ ___ _._ __ __ _ __
'Specific PAH compounds analyzed are presented in Table D.4.
"Moisture was critical for all samples except for the oil phase.
"TCLP metals include As, Ba, Cd, Cr, Pb, Hg, Se, and Ag.
"Total metals Include Sb, As, Ba, Be, Cd, Cr, Cu, Mn, Hg, Ni, Se, 71, Va, and Zn.
g
Q
1
Co
-------
inn n ii i i inn
III 1 1 111 1 1 Illliil
lin^^^ Ill ril'i ',|li'l!l!l:!lli" I"!!' riill'lfi ' '.Ml'li ill i'lllif IIHSll' hWSi * MH^^^ I:TH^^^^^^ PI
' ^ ' : ; " " '''':': j^ ^""
Case Histories
" ; ' ""
' "
iiiiM^^^^^^^^^^^^^ 1 i nin^^
ii
ป '
Table 13.22
PAH Removal Efficiencies
Sediment A
Treated
FAHAnalyte Feed" Solids' % Removal1"
Sediment B
Treated
Feed" Solids" % Removal11
Acenaphthene 68 13 98.1 12.800 42 99.7
'' ;;'"1 ":" ' '" :' '"" "; ::''l":' : 'A'cenaphlylerie '"": < 16 <0.8 - " '"210 6.6 96.9
Anthracene 22 13 94.1 2,370 16 993
Benzo(a)anthracene 25 052 9Z9 1,050 47 99.6
Benzo(a)pyrene 24 034 98.6 810 4;6 99.4
Benzo(b)fluoranthene 23 036 98.4 857 4.1 993
iii linn in i in i i mi
1 n, 4 nii
1^ Ill I';:!;.!'!! '
Hi iginniinnnni^iiiiinniilJniiilinfliii'iM!!!:1 ir :
nii.ninininiiii H irrni niiiin11,, .r
il?""
tX*. :,"ri 'sis i;1!:
Mซ i MBSt. r:
Benzo(k)fli
i 1 1 n in i in iiii i i in
Benzo(ghi)
Chrysene
Dibenz(a,h
Fluoranthei
' ' ' ' ' "" Fluorene
., , Indeno(l,2,
',i'i,,ttiiw ''" -"i'1'!!,1 '"'',;,"! ";: >
Naphthaleri
loranthene 17 022 98.7
pcrylene" 15 ' 02^"'' '" SSjtt
""25 032 975
533 3.6 993
"457 "' ' ' 23 """ 'MS
"937' 17 '' 993
)anthracene < 18 <0.76 - 140 <2.9 >97.9
,e 76 1.4 982 1,280 16 99.6
51 1.9 963 7,290 35 993
3-cd)pyrene 15 0.18 985 547 22 99.6
phthalene 25 3.7 852 6,410 83 98.7
",!' x , , i '' '' , I',,,:", ,,'ป', Ifi 111* II, ' , ,'v' ..."I!!!',,!1 < 1 , '''Kilt" 'I"|, i|, nl", 1,'
e < 18 5.1 - i
g,700 230 98.8
Phenanthrene 92 3.6 96.1 10,800 41 99.6
111!'! HI,) lli:i,i|||, ,j ' If! ;!!!!;, iiililll'lji , ;,!;' .y(*!j;. "l",,; , ", ,' ., i i( jfj 'lfl.:tja,Fil. .'"iajifj.'! t|, .'ill,"';!:"'!,!:! ill'lll.*" 1 -I, 'il'.' ill*!' E"" .Jlii'l, 'Ml,', njilr ,'f , i i
:,;;: " i!,:;!,,,,,,!,!:,:, ,;,,,::;;;:, ,.,.' :,pyrene 67 uo 983 2,810 12 99.6
' ' "': - '-" " - '" Total PAHs " 548" 22 96.0 ' "70,920 Slfl' 993
*Concentrat
, . ]" i ' ..ifitii.:;;!,, -, ; , .. , (Sediment A
Lllf r ' if i, , ill'',! i ifi'1 iii'iiiiiii'igiiifiiiii iiiiiinil: ' :',,,!,' ' i,,i n-1
lilllllfl ,11 :,i:' f" , l',, '' , ''" ,' I; ' ijv'niilniy'li , t'llllj ', ./.si i! ' ,i,ili,,
111 , :
ons reported in mg/kg (dry weight basis) and are the average of the three optimum runs for each sediment
= Runs 3, 4, and 5; Sediment B = Runs 2, 4, and 5).
* ii'" Feed Concentration-Treated Solids Concentration .1QO
,,1: , f "ii,,i ,:'| ,,:if, i"1; i,,1; jim1 ';,', ill i n i
i TI "i"1."'.,'11];,!1;1 **;:ซ;; ijlji; ,;",,, ;,*-; ;'! ;; "', '',. 1' .,J'[''^ $'''* >,,,: ;:.. i:1!""!1'! .i*;'!}, <{?(:;. \ !!'"'
ii:",,',:!!'' !:'',ii'!!i'J':''J'iS iii ' ' :':"ซ""';: ':-
maxi'1 i^jFiiLittitiin iiiiii n
,' : ! | l^A?,!',1,
inn i i i ill nil i i nil
'IhjJ.;^^,,,.'!! ?Ar .iM1,' ' >,Jl p.,l^lJjj|L^ .#.,4;!^ '^MM
'ป i 111 ' " "! , . ."" I1!, " , , . i "'' 'i i! , ' "l!l|1 . '!,i'i ' .'"l1!; ,|i '!!,,i ' 'Jlii In 'I; :|" 'ill |l III lilllllllil, 1 ,/ Hill, 1! If I-' ' , 'I, J t!!! 1
K :2v's111IfSl
-------
Table 13.23
PCB Removal Efficiencies
Parameter
Sediment A
Total PCBs-Feed
(mg/kg-dry weight)
_ Total PCBs-Treated Solids
to (mg/kg-dry weight)
W Percent Removal (%)
Sediment B
Total PCBs-Feed
(mg/kg-dry weight)
Total PCBs-Treated Solids
(mg/kg-dry weight)
Percent Removal (%)
Test Runs
R1 R2 R3 R4ป R5b Average" Standard Deviation c
733 6.41 8.01 11.8 16.4 lm 4'1/42
<0.07 020 0.05 0.04 0.04 0.08/0.04 0.07/0.006
>99 96.9 99.4 99.7 99.8 99.2/99.7
364 316 495 . 462 497 427/425 82/96
1.5 Zl .12 1.8 1.4 1.6/1.8 0.35/0.35
99.6 993 99.8 99.6 99.7 99.6/99.6
"Concentrations reported for Run 4 are the average of three field replicate measurements.
'Concentrations reported for Run 5 are the average of samples analyzed in triplicate.
cTwo values are given; the first pertains to all five runs and the second pertains to the three optimum runs (Sediment A = Runs 3, 4, and 5 and Sediment B = Runs 2, 4, and 5).
Chapter 13
-------
a ; *ป!!
<=
,
1! i , : ซ r;!: I.-.1; !
: . . -- :; ~~ ---:- - ;::;i, ป! ,; '. -". ' ! ' - * - ;;: -~- : --.--' iv
Table 13.24
Oil and Grease Removal Efficiencies
Test Runs
Parameter Rl
Sediment A
Total Oil and Grease-Feed
(mg/kg-dry weight) 9,400
Total Oil and Grease-Treated
Solids (mg/kg-dry weight) 195
Percent Removal (%) 975
Sediment B
Total Oil and Grease-Feed
(mg/kg-dry weight) 66,400
Total Oil and Grease-Treated
Solids (mg/kg-dry weight) 1,800
Percent Removal (%) 97^
R2 R3 R4- R5"
7,800 7,400 6,600 6,700
169 203 65 65
97.8 973 99.0 99.0
116,000 67,300 167,00n ^^
ll33- 1,490 1,230 1,810
985 97.8 993 982
^^Concentrations r^ned for Run 4 are the average of three Held replicate measurements.
|ฃฐncenv.aaons reported for Run 5 are the average of samples analyzed in triplicate.
- 1 wo values are o;ซon- thg {j^, pertains to gi| five ^^ and ^ second pertains to the average of the three optimum runs (Sediment A =
Sediment B = Runs 2,4, and 5).
Average" Standard Deviation0
7,580/6,900 1,030/436
140/111 69/79
98.2/98.4 - : - ^~
103,000/127,000 41,600/35,300 . '. . .
1,530/1,460 266/310
985/98.9
Runs 3, 4, and 5 and
= ^
o
Q
in
CD
I
i"
en
-------
01
Triethylamine Concentrations
Table 13.25
Treated Solids, Product Water, and Oil Phases
Test Runs3 Standard
Parameter Claim Rl
Sediment A
Triethylamine in Treated
Solids (mg/kg) < 150 61.7
Triethylamine in Product
Water (mg/L) < 80 < 1
Triethylamine in Oil Phase
(%) NA.
Sediment B
Triethylamine in Treated
Solids (mg/kg) <150 106
Triethylamine in Product
Water (mg/L) < 80 < 1
Triethylamine in Product Oil
(mg/L) < 1,000
R2 R3 R4b R5 Average0 Deviation'
93.1 27.8 28.0 79.6 58/45 29.6/29.8
<1 <1 <1 22 <2/<2 -
65.8d
88.7 55 130 893 94/103 27.4/23.7
1.0 <1 <1 <1
-------
Case Histories
"!'hP Jill > illili
.!!:,!,'li!'1 . ', , I1
previous full-scale test conducted at a site in Georgia. Certain cost factors
which were not included in the treatment cost estimate were assumed to be
the responsibility of the site owner/operator. Costs associated with system
mobilization, site preparation, startup, and demobilization were also ex-
cluded from the treatment cost estimate. The reasoning used in making
these estimates, or omitting a particular cost category, is discussed in the
Applications Analysis Report.
The pilot-scale unit used in this demonstration operated at an average feed
rate oF4p!8 kg (90* Ib) of contaminated se^ment?day. The fall-scale com-
mercial unit is projected to be capable of treating 169 tonne/day (186 ton/
dayXTPb) of contaminated soil or sludge] The cost estimates are based on
the remediation of contaminated soil, sludge or sediment using the proposed
full-scale unit. The treatment cost is estimatedlo tie $123/tonne (|il2Aon|
if the system is on-line 60% of the time or $103/tonne ($94/ton) if the sys-
tem is on-line 80% of the time. Cost information is presented in the Appli-
cations Analysis Report for this demonstration.
"'"I ' ' ' , ! :'' f" , """ ,"''(' ' : ,: ' '' '|||||'|1|I!;1 ' "''" I
Conclusions
The B.E.S.T.ฎ solvent extraction process is designed to treat sludges,
" i, '', l!!"''ป " ,!, i '., '! ' i:,'i'I :i ..M* ,', 11 ,"!.,, ," tin i 11, , <ซ, MI, .ป, , , ,n', i i; ,
soils, and sediments contaminated with organic compounds. The system is
capable of physically separating organic contaminants, such as PAHs, PCBs,
and O&G from contaminated media and concentrating the organics for con-
taminant volume reduction. The prototype fufrscaie system is only appli-
cable to sludges, but the proposed full-scale system will be applicable to
soils and sediments as well. ." ' i " ' '".'""'"', '.',." "'. .'"!'".''..".'.".
The effectiveness of treatment can be illustrated from this demonstration
and from previous case studies. This demonstration removed at a minimum
96% of the PAHs, greater than 99% of the PCBs, and greater than 98% of
the O&G from the contaminated sediments.
' 1 i,:,"' , 'S'"1' i 'H!1'1!1 'I'
13.66
-------
Appendix A
LIST OF REFERENCES
Soil Washing
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I
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Westinghouse Hanford Company. 1994. 300-FF-l Operable Unit Physical Separation of Soils Pilot
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-------
I": & -
List of References
l!,;
;; :'::'yl': ^>!i'1.!.?;;' !^Jli^i^fn9'!
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neers. In review. |
Edwards, D., R. Luthy, and Z. Liu. 1991. Solubilization of polycyclic aromatic hydrocarbons in
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A.2
-------
Appendix A
Freeze, G.A., J.C. Fountain, G.A. Pope, and R.E. Jackson. 1995. Modeling the surfactant-enhanced
remediation of perchloroethylene at the Borden test site using the UTCHEM compositional simula-
tor. Surfactant-Enhanced Subsurface Remediation-Emerging Technologies. D.A. Sabatini, R.C.
Knox, and J.H.Harwell (eds.). Washington, DC: American Chemical Society.
Frederick, Kevin. 1995. Private communication. Wyoming Department of Environmental
Quality. May.
Haley, J.L., B. Hanson, C. Enfield, and J. Glass. 1991. Evaluating the effectiveness of ground water
extraction systems. Ground Water Monitoring Review. Winter: 119-124.
Jin, M., M. Dilshad, D.C McKinney, G.A. Pope, K. Sepehinoori, and C. Tilbury. 1994. American
Institute of Hydrology Conference. Minneapolis, MN. pp 131-159.
Judge, C., P. Kostecki, and E. Calabrese. 1997. State Summaries of Soil Cleanup Standards, Soil,
and Groundwater Cleanup. November.
Keeley, J. 1989. Performance evaluations of pump and treat remediation. US EPA, EPA/540/
4-89-005.
Knox, R.C., D.A. Sabatini, J.H. Harwell, C.C. West, F. Bkiha, C. Griffin, D. Wallick, and L.
Quencer. 1995. Traverse City field test. Presented at In Situ Surfactant Use Workshop. Kansas
City.MO. September.
Krebs-Yuill, B., J.H. Harwell, D.A. Sabatini, and R.C. Knox. 1995. Economic considerations in
surfactant-enhanced pump-and-treat remediation. Surfactant-Enhanced Subsurface Remediation,
Emerging Technologies. D.A. Sabatini, R.C. Knox, and J.H. Harwell (eds.). Washington, DC:
American Chemical Society, pp 265-278. i
I
Lagrega, M.D., P.L. Buckingham, and J.C. Evans. 1994. Hazardous Waste Management. The
Environmental Resources Management Group. New York: McGraw-Hill. pp968.
Laman, Jerry T. 1989. A discussion of the operating history at an ammonium carbonate solution
mine pilot test. In Situ Recovery of Mineral. Volume I. New York: Engineering Foundation.
MacDonald, J.A. and M.C. Kavanaugh. 1994. Restoring contaminated groundwater: an achievable
goal? Environmental Science & Technology. August: 362A-368A.
Magee, B.R., L.W. Lion, and A.T. Lemley. 1991. Environmental Science Technology. 25:323-331.
McCoy & Associates. 1990. Innovative slurry wall designs for containment of ground-water con-
tamination. The Hazardous Waste Consultant. May/June: 1-9.
McKee, C.R., J.F. Schabron, and S.C. Way. 1995. Field screening gets a boost. International
Ground Water Technology. 1(5). May.
McKee, C.R. and D.A. Sabatini. 1995. Private communication. September 3.
McKee, C.R. and D. Whitman. 1991. Designing in situ waste recovery systems. Short course
presented to Association of Groundwater Scientists and Engineers. Dublin, OH.
McKee, C.R. and S.C. Way. 1994. Unpublished report. :
McKee, C.R., S.C. Way, R.Gunn, and J. Evers. 1981. Hydrologic site characterization for in situ
coal gassification. In Situ. 5(3). New York: Marcel Dekker, Inc.
McPhillips, L.C., R.C. Pratt, and W. S. McKinley. 1991. Effective Groundwater Remediation at the
United Chrome Superfund Site. US EPA. Pittsburgh, PA. Air and Waste Management Association.
Merritt, Robert C. 1971. The extraction metallurgy of uranium. In-Situ Recovery of Mineral.
Volume I. Golden, CO: Colorado School of Mine Research Institute.
A.3
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""::T ;1
List of References
. . . . I
Murphyi Jack. 1991. Designing in-situ waste recovery systems. Short course presented to the
Association of Ground Water Scientists and Engineers. Dublin, OH.
MI ii I ' , '; ;;!j ',:: ,, ,i, ,. , .i* .!" , : ."is ป..
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Appendix A
US EPA. 1991. Engineering Bulletin: In Situ Soil Flushing. EPA/542/2-91/021.
US EPA. 1992. Evaluation of ground-water extraction remedies. Phase II, Volume 1, Summary
Report. Office of Emergency and Remedial Response. Washington, DC. February.
US EPA. 1992. A Guide to In Situ Soil Flushing. EPA/542/F-92/007.
US EPA. 1993. Remediation Technologies Screening Matrix and Reference Guide. EPA542-B-93-
005. July.
US EPA. 1995. Abstracts of Remediation Case Studies. EPA-542-R-95-001. US EPA, Office of
Emergency and Remedial Response. Washington, DC.
Ward, Calvin H., Raymond C. Loehr, Evan K. Nyer, Michael R. Piotrowski, J. Michele Thomas,
James C. Spain, John T. Wilson, and Robert D. Morris. 1995. Innovative Site Remediation Technol-
ogy Bioremediation. Annapolis, MD: American Academy of Environmental Engineers.
Way, S.C. and C.R. McKee. 1982. In situ determination of three-dimensional aquifer
permeabilities. Ground Water. 1(2): 594-603.
Way, S.C. and C.R. McKee. 1990. Designing In situ Waste Recovery Systems. Presented to the
Association of Groundwater Scientists and Engineers. Cincinnati, OH (August) and San Francisco,
CA (October).
Zheng, C., G.D.Bennett, and C.B. Andrews. 1992. Reply to discussion by Robert D. McCaleb of
analysis of ground-water remedial alternatives at a Superfund site. Ground Water. 30(3):440-442.
Solvent/Chemical Extraction
American Society for Testing and Materials (ASTM). 1990. Standard Test Method for Particle Size
Analysis of Soils, D 442-63. ASTM.
American Society for Testing and Materials (ASTM). 1992. Standard Test Method for Laboratory
Determination of Water (Moisture) Content of Soil and Rock, D 2216-90. ASTM.
Blank, Z., B. Rugg, and W. Steiner. 1989. LEEP-Low Energy Extraction Process: New Technology
to Decontaminate PCB-Contaminated Sites. EPA SITE Emerging Technologies Program.
Randolph, NJ: Applied Remediation Technology, Inc.
Cash, A.B. 1991. Proposal for participation in the U.S. Environmental Protection Agency's SITE
Program. Oklahoma City, OK.
Cash, A.B. 1992. Telephone conversation with Mark C. Meckes. June.
CF Systems Brochure. 1992. Solvent extraction treatability study profile. Waltham, MA.
Donnelly, James R., Robert Ahlert, Richard J. Ayen, Sharon R. Just, and Mark C. Meckes. 1994.
Innovative Site Remediation Technology Solvent/Chemical Extraction. Annapolis, MD: American
Academy of Environmental Engineers.
Environment Today. 1991. Carver-Greenfield Process tries cleaning oily solids. Environment
Today. January/February. i
Evans, Gordon M. 1990. Estimating Innovative Technology Costs for the SITE Program. J.Air&
Waste Manage. Assoc. 40(7): 1047-1051.
Hazardous Waste Consultant 1991. Carver-Greenfield Process applied to petroleum-contaminated
soils and sludges. The Hazardous Waste Consultant. January/February: 1.7-1.9.
A.5
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List of References
Holcombe,f.C.andE.A.Kollitides. 1991. Drying fuels with the barver-Greenfield Process. Paper
presented at the Clean Energy from Waste Symposium during the ACS National Meeting. New
York. August 26-3D.
Lau P.L 1991. Drying of alum sludge using the Carver-Greenfield Process. Contra Costa Water
District. Concord, CA. August. Unpublished.
Massey MJ andS.Darian. 1989. ENSR process for the extractive decontamination of soils and
sludges'. Paper presented at the PCB Forum, US EPA International Conference for the Remediation
of PCB Contamination. Houston, TX. August 29-30.
Meckes, M.C., E. Renard, J. Rawe, and G. Wahl. 1992. Solvent extraction processes: a survey of
systems in the SITE program. /. Air & Waste Manage. Assoc. 8:42.
Meckes, M.C., tl. Wagner, J. Tillmari; and srkrietmeyer. 1993" Demonstration of the basic extract
live sludge treatment process. J. Air & Waste Manage. Assoc. 43(9).
Meckes, Mark C, Scott Engle, and Bill Kosco. 1996. Site demonstration of Terra-Kleen response
group's mobile solvent extraction process. J.Air & Waste Manage. Assoc. 46(10). October.
Meckes, Mark C., Joseph Tillman, Lauren Drees, and Eric Saylor. 1997. Removal of PCBs
from a contaminated soil using CF-Systems' solvent extraction process. /. Air Waste Manage.
Assoc. In Press. .
National Fire Protection Association (NFPA). 1990. Solvent extraction. Industrial Fire Hazards
Handbook. 3rd edition, pp785-8ll4
NETAC. 1991. Carver-Greenfield Process for oily waste extraction. NETAC Environmental Prod-
uct Profiles. National Environmental Technology Applications Corporation. Pittsburgh, PA. April.
Pedersen, J W. 1991. Use of the Carver-Greenfield Process for remediating petroleum contaminated
soil. Master's Thesis. The Cooper Union for the Advancement of Science and Art. April 15.
Robbins,LC. 1990. A pemianent solution to hazardous waste: tie B.E.S.T.* solvent extraction
process. Marketing Information from Resources Conservation Company. Bellevue, WA.
Tose, M.K. 19871 Removal of polychlonnated biphenyls (PCB'st from sludges and sediments with
B.E.S.T. extraction technology. Paper presented at 1987 Annual Meeting with Biotechnology
Conference. New York. November 15-20.
Trowbridge, TJD., T.C. Holcombe, and' E.L"iCoilitides": 1991 Extraction and drying of superfund
wastes with the Carver-Greenfield Process. Paper presented at Third Forum on Innovative Hazard-
ous Waste Treatment Technologies: Domestic and International. Dallas, TX. June 11-13.
Office of the Federal Register." 1994. Title 40: Protection of the'Environment, Part 261. U.S.
Code of Federal Regulations. Washington, DC: National Archives and Records Administration.
Office of the Federal Register. 1996. 1996 Code of Federal Regulations, Title 40, Part 261, SubpartD.
Lists of Hazardous Wastes. Washington, DC: National Archives and Records Administration.
US EPA. 1989. Dehydro-Tech Corporation (Carver-Greenfield) process for extraction of oily waste.
The Superfund Innovative Technology Evaluation Program: Technology Profiles. 2nd edition. EPA/
540/5-89/013. Cincinnati, OH. pp31-32. November.
' ' 'I'1" < ''" ".'I'. "Jllp'"'' ' . I !"i " . ' " ' .: ."' J .'.
US EPA. 1990a. CF Systems organics extraction process, New Bedford Harbor, Massachusetts,
applications analysis report. EPA/540/A5-90/002. Cincinnati, OH. August.
US EPA. 1990b. Dehydro-Tech Corporation (Carver-Greenfield) process for extraction of oily
waste. The Superfund Innovative Technology Evaluation Program: Technology Profiles. 3rd edition.
EPA/540/5-90/006. Cincinnati, OH. pp 36-37. November.
A.6
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Appendix A
US EPA. 1990c. Engineering Bulletin: Soil Washing. EPA/540 '/2-090/017. US EPA Risk Reduc-
tion Engineering Laboratory, Cincinnati, OH. September.
US EPA. 1991a. Dehydro-Tech Corporation (Carver-Greenfield) process for extraction of oily
waste. Innovative Treatment Technologies Overview and Guide to Information Sources. Cincin-
nati, OH. pp5-13. October.
US EPA. 1991b. Dehydro-Tech Corporation (Carver-Greenfield) process for extraction of oily
waste. The Superfund Innovative Technology Evaluation Prog ram: Technology Profiles. 4th edition.
EPA/540/5-91/008. Cincinnati, OH. pp 58-59. November.
US EPA. 1991c. Synopses of federal demonstrations of innovative s ite remediation technologies.
EPA/540/8-91/009. Cincinnati, OH. May.
US EPA. 1992a. The Carver-Greenfield Process, Dehydro-Tech Corporation, Applications Analysis
Report. EPA/540/AR-92/002. Washington, DC: US EPA. August.
US EPA. 1992b. Guide for conducting treatability studies und'er CERCT.A: solvent extraction.
EPA/540/R-92/016a. Cincinnati, OH.
US EPA. 1992c. Literature survey of innovative technologies .for hazardoi is waste site remediation
1987-1991. Washington, DC. February. Preliminary draft.
US EPA. 1992d. The Carver-Greenfield process. Superfund Innovative Tea \nology Evaluation
Program: Demonstration Bulletin. EPA/540/MR-92/002. Cincinnati, OH. February. ',
US EPA. 1992e. The Superfund Innovative Technology Evaluation Program: 1 Technology Profiles.
EPA/540/R-92/077. 5th edition. Cincinnati, OH. November,
US EPA. 1992f. Technology Evaluation Report: The Carver Greenfield Process.. Dehydro-Tech
Corporation. NTIS Document Order No. PB92-217462AS. Washington, DC: Ut S EPA. August.
US EPA. 1992g. Test Methods for Evaluation Solid Waste. 3rd edition. Office of'Solid Waste and
Emergency Response. Washington, DC.
US EPA. 1993. Resources Conservation Corporation B.E.S.T. solvent extraction technology, appli-
cation analysis report. EPA/540/AR-92/079. Cincinnati, OH.
US EPA. 1994a. Solvent extraction treatment. Engineering Bulletin. EPA/540/5-94/.'503. Cincin-
nati, OH.
US EPA. 1994b. Superfund Innovative Technology Evaluation Program, Technology Profiles. EPA/
540/R-94/526. 7th edition. Cincinnati, OH.
US EPA. 1996. Innovative Treatment Technologies: Annual Status Report. EPA-542-R-96-010.
8th edition. Washington, DC.
US EPA. 1997. Terra-Kleen Response Group, Inc., Solvent Extraction Technology: Final .Innova-
tive Technology Evaluation Report. National Risk Management Research Laboratory, Offici e of
Research and Development, US EPA. Cincinnati, OH. Pending Publication.
Weimer, L.D. 1989. The B.E.S.T. solvent extraction process applications with hazardous sh'adges,
soils, and sediments. Paper presented at Third International Conference New Frontiers for Haiiard-
ous Waste Management Pittsburgh, PA. September. '
A.7
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THE WASTECHฎ MONOGRAPH SERIES (PHASE II) ON
INNOVATIVE SITE REMEDIATION TECHNOLOGY:
DESIGN AND APPLICATION
This seven-book series focusing on the design and appliication of innovative site remediation
technologies follows an earlier series (Phase 1,1994-1995) which cover the process descriptions,
evaluations, and limitations of these same technologies. The success of that series of publications
suggested that this Phase II series be developed for practitioners in need of design information
and applications, including case studies.
WASTECHฎ is a multiorganization effort which joins in partnership the Air and Waste Manage-
ment Association, the American Institute of Chemical Engineers, the American Society of Civil
Engineers, the American Society of Mechanical Engineers, the Hazardous Waste Action
Coalition, the Society for Industrial Microbiology, the Sloil Science Society of America, and
"he Water Environment Federation, together with the American Academy of Environmental
Sngineers, the U.S. Environmental Protection Agency, Ihe U.S. Department of Defense, and the
J.S. Department of Energy.
A Steering Committee composed of highly respected members of each participating organization
with expertise in remediation technology formulated and guided both phases, with project
management and support provided by the Academy. Each monograph was prepared by a Task
Group of recognized experts. The manuscripts were subjected to extensive peer reviews prior to
publication. This Design and Application Series includes:
Vol 1 - Bloremediation
Principal authors: R. Ryan Dupont, Ph.D., Chair,
Utah State University; Clifford J. Bruell, Ph.D.,
University of Massachusetts; Douglas C. Downey,
Parsons Engineering Science; Scott G. Hiding,
USEPA; Michael C. Marley, Ph.D., Environgen, Inc.;
Robert D. Norris, Ph.D., Eckenfelder, Inc.; Bruce
Pivetz, USEPA.
/ol 2 - Chemical Treatment
Principal authors: Leo Weitzman, Ph.D., LVW
Associates, Chair; Irvin A. Jefcoat, Ph.D., University
if Alabama; Byung R. Kim, Ph.D., Ford Research
Laboratory.
/ol 3 - Liquid Extraction Technologies:
ioil Washing/Soil Flushing/Solvent Chemical
'rincipal authors: Michael J. Mann, P.E., DEE,
VRCADIS Geraghty & Miller, Inc., Chair, Richard
F. Ayen, Ph.D., Waste Management Inc.; Lome G.
Sverett, Ph.D., Geraghty & Miller, Inc.; Dirk
Jombert II, P.E., LIFCO; Mark Meckes, USEPA;
Chester R. McKee, Ph.D., In-Situ. Inc.; Richard P.
Praver, P.E., Bergmann USA; Phillip D. Walling,
r., P.E., E. I. DuPont Co. Inc.; Shao-Chih Way,
h.D., In-Situ, Inc.
'ol 4 - Stabilization/Solidification
tincipal authors: Paul D. Kalb, Brookhaven National
^boratory, Chair, Jesse R. Conner, Conner Technolo-
ies, Inc.; John L. Mayberry, P.E., SAIC; Bhavesh R.
'atel, U.S. Department of Energy; Joseph M. Perez, Jr.,
tattelle Pacific Northwest; Russell L. Treat, MACTEC
Vol 5 - Thermal Desorption
Principal authors: William L. Troxler, P.E., Focus
Environmental Inc., Chair, Edward S. Alperin, IT
Corporation; Paul R. de Percin, USEPA; Joseph H.
Button, P.E., Canonie Environmental Services, Inc.;
JoAnni S. Lighty, Ph.D., University of Utah; Carl R.
Palmer, P.E., Rust Remedial Services, Inc.
Vol 6 - Thermal Destruction
Principal authors: Francis W. Holm, Ph.D., SAIC, Chair,
Carl R. Cooley, Department of Energy; James J.
Cudahy, P.E., Focus Environmental Inc.; Clyde R.
Dempsey, P.E., USEPA; John P. Longwell, Sc.D.,
Massachusetts Institute of Technology; Richard S.
Magee, Sc.D., P.E., DEE, New Jersey Institute of
Technology; Walter G. May, Sc.D., University of Illinois.
Voi 7 - Vapor Extraction and Air Sparging
Principal authors: Timothy B. Holbrook, P.E., Camp
Dresseir & McKee, Inc., Chair, David H. Bass, Sc.D.,
Groundwater Technology, Inc.; Paul M. Boersma,
CH2M Hill; Dominic C. DiGuilio, University of
Arizona; John J. Eisenbeis, Ph.D., Camp Dresser &
McKee, Inc.; Neil J. Hutzler, Ph.D., Michigan
Technological University; Eric P. Roberts, P.E., ICF
Kaiser Engineers, Inc.
The monographs for both the Phase 1 and Phase II
series may be purchased from the American Academy
of Environmental Engineer^*, 130 Holiday Court, Suite
100, Annapolis, MD, 21401; Phone: 410-266-3390,
Fax: 410-266-7653, E-mail: aaee@ea.net
*U.S. GOVERNMENT PRINTING OFFICE: 1998-411-B95X9Q494
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