o
Committee on the
Challenges of
Modern Society
                                EPA/600/R-93/012a
                                February 1993
     Demonstration of Remedial
       Action Technologies for
Contaminated Land and Groundwater

              Final Report
               Volume 1
                Number 190
          North Atlantic Treaty Organization
                 1986-1991

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                                          COMMITTEE ON
                                       THE CHALLENGES OF
NATO/CCMS                    MODERN SOCIETY
                                            Number 190
                  FINAL REPORT
                        Volume 1
       Demonstration of Remedial Action Technologies
           for Contaminated Land and Groundwater
                    Pilot Study Directors

              Donald E. Sanning, United States - Director
               Vokler Franzius, Germany - Co-Director
              Esther Soczo, The Netherlands - Co-Director


                   Participating Countries

                   Canada         Germany
                   Denmark      The Netherlands
                    France        United States
                Observer and Other Countries

                   Austria           Norway
                    Italy            Turkey
                    Japan       United Kingdom


                          Authors

              Thomas O. Dahl        Donald E. Sanning
             Merten Hinsenveld       James W. Schmidt
             Stephen C. James       Michael A. Smith
               Norma Lewis            Sjef Staps
            Robert F. Olfenbuttel, author and General Editor
                       1986-1991

                                            &f} Printed on Recycled Paper

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Abstract
This publication reports on the results of the NATO/CCMS Pilot Study "Demonstration of Remedial Action Tech-
nologies for Contaminated Land and Ground Water" which was conducted from 1986 through 1991.  The Pilot
Study was designed to identify and evaluate innovative, emerging and alternative remediation technologies and to
transfer technical performance and economic information on them to potential users.

Twenty-nine remediation technology projects were examined which treat, recycle,  separate or concentrate con-
taminants in soil, sludges, and ground water.  The emphasis was on in situ and on-site technologies; however, in
some cases, e.g., thermal treatment, fixed facilities off-site were also examined.  Technologies included are: ther-
mal, stabilization/solidification, soil vapor extraction,  physical/chemical extraction, pump and treat ground water,
chemical treatment of contaminated soils, and microbial treatment.

This report serves as a reference and guide to the potential application of technologies to various types of con-
tamination; it is not a design manual. Unique to this study is the examination and reporting of "failures" as well as
successes.

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Acknowledgements


The Pilot and Co-Pilot Study Directors thank all who made significant contributions to the work of the Pilot Study:

Those representing their countries made a major contribution to the direction of the Study by recommending
projects within their respective countries which would be of particular interest to this Study, and by discussing the
regulatory and general environmental technology situations in their countries.

The various chapters were written by the respective authors after reviewing reports prepared on the Case Studies
for the meetings of the Study Group.

Good use was made  of the NATO/CCMS Fellowship Program to further enhance the value of the Study and a
number of Fellows contributed directly to the preparation of this report. Robert Olfenbuttel of Battelle also served as
the general editor for the report, supported by Virginia R. Hathaway of JACA Corp., editor.

Expert speakers, often supported by NATO/CCMS travel funds, participated in the workshops and conferences of
the Pilot Study and contributed to the work of the Pilot Study Group.

Until his retirement, the NATO/CCMS International Staff was represented by  the former CCMS Director, Mr. Ter-
rance Moran. Dr. Deniz Beten replaced Mr. Moran and attended the Fifth International Meeting.

Ms. Naomi Barkley of the Office of Research and Development, Risk Reduction Environmental Laboratory, Super-
fund Technology Demonstration Division, U.S. Environmental Protection Agency served as Task Project Manager
for this project.

The names and addresses of all participants in the Study Group are given in Volume Two.
                                                iii

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Contents: Volume 1

Foreword	i
Abstract	  ii
Acknowledgements	iii
Figures	 x
Tables	xi

Chapter 1
Introduction	 . 1
   Donald E. Sanning and Robert F. Olfenbuttel
1.1   Background   	 1
1.2   Structure of the Study  	 1
     1.2.1   Categories of the Technologies Examined	 2
     1.2.3   How the Technology Information is Presented	2
     1.2.4   Summary of Conclusions	3
1.3   Contributions by CCMS Fellows	3
1.4   Contents of Volume 2	3

Chapter 2
Thermal Technologies	7
   Stephen C. James and Gregory L Stacy
2.1   Introduction   	7
2.2   Case Studies Chosen  	11
     2.2.1   Case Study 2-A: Rotary Kiln Incineration, The Netherlands  .  . .	11
     2.2.2   Case Study 2-B: Indirect Heating in a Rotary Kiln, Germany	12
     2.2.3   Case Study 2-C: Off-site Soil Treatment, Japan	13
     2.2.4   Case Study 2-D: Electric Infrared Incineration, United States	13
     2.2.5   Case Study 2-E: In Situ Vitrification, United States	14
2.3   Background of the Case Studies as a Group  	14
2.4   Performance Results	14
2.5   Residuals and Emissions  	15
2.6   Factors To Consider for Determining Applicability of the Technology	17
2.7   Costs	20
2.8   Future Status of Case Study Processes and Thermal Technologies as a Whole	21

Chapter 3
Stabilization/Solidification Technologies	23
   Merten Hinsenveld
3.1   Introduction	23
     3.1.1   Place of the Techniques in a Broad Sense	23
     3.1.2   The Stabilization/Solidification Process	24
3.2   Case Studies Chosen  	25
     3.2.1   Case Study 3-A: In Situ Lime Stabilization (EIF Ecology), France   	25
     3.2.2   Case Study 3-B: Petrifix Process (TREDi), France	25

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     3.2.3   Case Study 3-C: Portland Cement (Hazcon, presently IM-Tech), United States	25
3.3  Background of Case Study Sites as a Group	25
3.4  Performance Results	.25
3.5  Residuals and Emissions	27
3.6  Factors to Consider for Determining the Applicability of the Technology		27
     3.6.1   Limitations and Restrictions on the Use of the Technology	27
     3.6.2   Steps in Determining the Applicability of S/S Treatment	28
3.7  Costs	29
     3.7.1   General Cost Factors		29
     3.7.2   Costs Of The Hazcon Treatment System	30
3.8  Future Status of Case Study Processes and the Technology as a Whole	30

Chapter 4
Soil Vapor Extraction Technologies	33
   Norma Lewis
4.1  Introduction	. .  .  .	33
4.2  Case Studies Chosen	35
     4.2.1   Case Study 4-A:  In Situ Soil Vacuum Extraction, The Netherlands	35
     4.2.2   Case Study 4-B: Vacuum Extraction of Soil Vapor, Verona Well Field Superfund Site,
            United States  	,. . .	36
     4.2.3   Case Study 4-C: Venting Methods, Hill Air Force Base, United States	36
     4.2.4   Additional Case Studies, United States	36
4.3  Background of the Case Study Sites as a Group	 . 37
 4.4  Performance Results	38
     4.4.1   Analytical Procedures	38
     4.4.2   General Effectiveness of the SVE Process	38
     4.4.3   Removal of Nonhalogenated Solvents	  .	 39
     4.4.4   Removal of Gasolines and Jet Fuels	39
     4.4.5   Removal of Halogenated Solvents	40
     4.4.6   Usefulness for Enhancing In Situ Biodegradation	 . 40
4.5  Residuals and Emissions		41
4.6  Factors to Consider for Determining Applicability of the Technology	43
4.7  Costs	44
4.8  Future Status of Case Study Processes and the SVE Technology as a Whole	 48

Chapter 5
Physical/Chemical Extraction Technologies	53
   Merten Hinsenveld
5.1  Introduction  	53
     5.1.1   Place of the Techniques in a Broad Sense	53
     5.1.2   Principle of Extraction Techniques	54
     5.1.3   Principle of Electro-reclamation	'..'.'	 . .	 . . 55
5.2  Case Studies Chosen	.55
     5.2.1   Case Study 5-A: High Pressure Soil Washing (Klockner), Germany	 55
     5.2.2   Case Study 5-B: Vibration (Harbauer), Germany	.• .	55
     5.2.3   Case Study 5-C: Jet Cutting Followed by Oxidation (Keller), Germany ........... .56

                                               vi

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     5.2.4   Case Study 5-D: Electro-reclamation (Geokinetics), The Netherlands	56
     5.2.5   Case Study 5-E: In Situ Acid Extraction (TAUW/Mpurik), The Netherlands   	56
     5.2.6   Case Study 5-F: Debris Washing, United States   . .  .	 . 56
5.3  Background of the Case Study Sites as a Group	56
5.4  Performance Results	56
5.5  Management of Residuals	58
5.6  Limitations or Restrictions to the Use of the Techniques	58
5.7  Costs	58
     5.7.1   Fixed Costs	  .  . .	58
     5.7.2   Variable Costs	60
     5.7.3   Total Costs	..-••••	61
5.8  Future Status of Case Study Processes and Extraction Technologies as a Whole	62

Chapter 6
Pump and Treat Ground Water	65
   J.W.Schmidt
6.1  Introduction	65
6.2  Case Studies Chosen	65
     6.2.1   Case Study 6-A: Decontamination of Ville fVlercier Aquifer for Toxic Organics, Ville
            Mercier, Quebec, Canada. . .	 ...	66
     6.2.2   Case Study 6-B: Evaluation of Photo-oxidation Technology (Ultroxฎ International),
            Lorentz Barrel and Drum Site, San Jose, California, United States.	66
     6.2.3   Case Study 6-C: Zinc Smelting Wastes and the Lot River, Viviez, Averyron, France  .... 67
     6.2.4   Case Study 6-D: Separation Pumping, Skrydstrup, Denmark   	.67
6.3  Background of the Case Study Sites as a Group  	68
6.4  Performance Results	69
     6.4.1   Effectiveness of Aquifer Remediation at Ville Mercier	69
     6.4.2   Effectiveness of Treatment Technologies	69
     6.4.3   Lessons Learned on How to Improve Effectiveness	70
6.5  Residuals and Emissions   	:	71
6.6  Factors and Limitations  to Consider for Determining Applicability of the Technology	71
     6.6.1   Application of Pump and Treat	71
     6.6.2   Application of Ground Water Treatment Technologies  	71
     6.6.3   Availability of the Technologies	72
6.7  Costs	72
6.8  Future Status of Case Study Processes and the Technology as a Whole	73
     6.8.1   Air Stripping and Activated Carbon	 73
     6.8.2   Photo-oxidation Technologies	 74
     6.8.3   Precipitation Technology	75

Chapter 7
Chemical Treatment of Contaminated Soils: APEG	77
   Michael A. Smith
7.1  Introduction	......;..	77
     7.1.1   Applicability		77
     7.1.2   Variations on the APEG Process	78
                                                VII

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     7.1.3   Operational Requirements	.78
 7.2  Case Study Chosen	 ! ..;.....................:.. 79
     7.2.1   Background  . .	,	 79
     7.2.2   The KPEG Demonstration Project	 .  : .  . .:.•'... ... 80
 7.3  Performance Results	 80
 7.4  Residuals and Emissions  	80
 7.5  Limitations	.80
     7.5.1   Inherent in the Technology		.80
     7.5.2   Health and Safety	 ^  ..:....... 80
 7.6  Costs		 82
 7.7  Factors to Consider for Determining Applicability of the Technology		 .  . .  . .82
 7.8  Future Status of the Technology	 .  .	82

 Chapters
 Microbial Treatment Technologies  .  .	..'-. .'."	;................. 85
   SJefStaps
 8.1  Introduction	 ...  . .  . .  . .  . .  ... .  . ,	 85
 8.2  Case Studies Chosen	  ... .  ; ...... .  . ....... 86
     8.2.1   In Situ Projects	  . .  . . •]'• . . .  . ...  '. ;  . .  : .  ..... .. ,  ......... 86
            8.2.1.1  Case Study 8-A: Aerobic/Anaerobic In Situ Degradation of Soil and Ground
                  Water, Skrydstrup, Denmark		.86
            8.2.1.2 Case Study 8-B: In Situ Biorestoration of Soil, Asten, The  Netherlands ....... 86
            8.2.1.3 Case Study 8-C: In Situ Enhanced Aerobic Restoration of Soil and Ground Water,
                  Eglin Air Force Base (AFB),  United States	.86
     8.2.2   Ex Situ Projects  .	 86
            8.2.2.1  Case Study 8-D: Bidlogical Pre-treatment of Ground Water, Bunschoten, The
                  Netherlands	86
            8.2.2.2 Case Study 8-E: Rotary Composting Reactor for Oily Soils, Soest, The
                  Netherlands	87
 8.3  Background of the Case Study Sites as a Group  	88
 8.4  Performance Results	89
     8.4.1    Common Effectiveness of Process Units	90
     8.4.2   Effectiveness of the Rotating Composting Bioreactor on Diesel Fuel	91
     8.4.3  Lessons Learned on How to Improve Effectiveness	91
     8.4.4  Lessons Learned In Site Preparation and Testing	91
8.5  Residuals and Emissions   	92
8.6  Factors and Limitations to Consider for Determining Applicability of the Technology	92
8.7  Costs	93
8.8  Future Status of Case Study Processes and Microbial Treatment as a Whole	 94
     8.8.1   Future Status of Case Studies	94
     8.8.2   Future Status of Microbial Treatment in General  	94

Chapter 9
Selecting Remedies at a Complex Hazardous Waste Site	97
   Thomas O. Dahl
9.1   Introduction  	97
9.2  Interim Studies/Remedies	98

                                            viii •

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9.3  Litigation	-	 • ........	99
9.4  The Remedial Investigation/Feasibility Study (RI/FS) Process  	.99
9.5  Stringfellow Site RI/FS	102
9.6  Remedy Selection at Stringfellow	 .  . .	  105
9.7  Conclusions	•  • •  • •  • •  106

Chapter 10
Conclusions and Recommendations	109
   Donald E. Sanning and Robert F. Olfenbuttel
10.1 Introduction	109
10.2 Specific Technology Chapter Conclusions	 .  . .  .•...;.%  ...... ..... .  . .  . .  . .  109
    10.2.1  Chapter 2: Thermal Technologies	,.,.,,.........  109
    10.2.2  Chapter 3: Stabilization/Solidification (S/S) Technologies	110
    10.2.3  Chapter 4: Soil Vapor Extraction (SVE) Technologies	110
    10.2.4  Chapter 5: Physical/Chemical Extraction Technologies		  110
    10.2.5  Chapter 6: Pump and Treat Ground Water  .	  110
    10.2.6  Chapter 7: Chemical Treatment of Contaminated Soils: APEG	  111
    10.2.7  Chapter 8: Microbial Treatment Technologies	111
    10.2.8  Chapter 9: Selecting Remedies at a Complex Hazardous Waste Site  ...........  111
    10.2.9  Appendix: In Situ Vitrification  .  . .  . . ...'.:. .  . . .\  ....'.  .'.' :'.  .	  112
10.3 General Conclusions	  . . .	112
    10.3.1  Remediation	  . . ....... .  . .  .  . .  .". .	 .  112
    10.3.2  Technology Transfer	.'. .'.  . •>['.  .,,  .'.'-..,."", .  .-. .  : ....  ........  114
    10.3.3  Research	  114
10.4 Recommendations	,..,.,.....,.	  115
                                              IX

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Figures

Figure 4-1.  Soil vapor extraction system	34
Figure 4-2.  Two types of soil venting systems, (a) Use of passive vapor wells to prevent
            migration of off-site contaminant vapors, (b) Water table rise caused by the
            applied vacuum	44
Figure 4-3.  Guidelines for deciding if SVE is applicable	45
Figure 5-1.  The basic processes in extraction installations	54
Figure 7-1.  Schematic diagram of a typical glycol dehalogenation treatment facility	78
Figure 7-2.  APEG reactions	79
Figure 7-3.  Block diagram of internal flow of materials	81
Figure 8-1.  Cross-section of the soil with  an overview of the restoration process	87
Figure 8-2.  Eglin AFB Site profile	88
Figure 8-3.  Flow diagram of the RBCs and compost filters	 89
Figure 8-4.  Biological treatment process in the rotating bioreactor.	89
Figure 9-1.  Location of the Stringfellow Waste Disposal Site	98
Figure 9-2.  General site configuration by  1972 for disposal operations	98
Figure 9-3.  U.S. Superfund remedy selection process	100
Figure 9-4.  Approximate location of TCE contaminated ground water that extends from the
            Stringfellow Site into Glen Avon	104

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Tables
Table 1 -1.   Conclusions for NATO/CCMS final report; demonstration of remedial action
            technologies for contaminated land and ground water	
Table 2-1.   Numbers and types of hazardous waste incineration facilities in the United States.
Table 2-2.   Hazardous waste incineration facilities in Europe.	
Table 2-3.   Site data from U.S. hazardous waste incinerator projects	
Table 2-4.   Performance data for various U.S. hazardous waste incinerator projects	
Table 2-5.   European Community emission limits for municipal incinerators	
Table 2-6.   Typical incinerator operating conditions in the EC, as reported by manufacturers.  .
Table 2-7.   Methods to develop cleanup standards by country	  . .  ."	
Table 2-8.   Waste characteristics suitable for electric infrared incineration	 .  .  .
Table 2-9.   Typical costs of incineration of contaminated soils (in US$, 1988)	
Table 3-1.   Problem handled in these NATO/CCMS case studies	
Table 3-2.   Limitations of the case study techniques.	
Table 3-3.   Summary of estimated treatability costs for metals (x1000 US$, 1989)	
Table 3-4.   Estimated costs for the Hazcon System (in  US$, 1989).	  .  .
Table 4-1.   Summary of SVE case study information	
Table 4-2.   Reduction of weighted average TCE levels in soil, Groveland Well Site (TCE
            concentration in mg/kg)		
Table 4-3.   Characteristics limiting SVE feasibility - contaminant, soil, and site characteristics.
Table 4-4.   Factors affecting SVE treatment costs	
Table 4-5.   Terra Vac economic model (in US$, 1989). .	
Table 4-6.   Verona Well Field SVE costs (in US$,  1990)	
Table 4-7.   TCAAP Site D — Estimated construction and operating costs (in US$)	
Table 4-8.   TCAAP Site G — Estimated construction and operating costs (in US$)  	
Table 4-9.   Capital cost  estimation of SVE components (in US$, 1990)	
Table 5-1.   Problems handled in the NATO/CCMS case studies	
Table 5-2.   Limitations to the use of the case study techniques	
Table 5-3.   Summary of annual fixed costs (in US$ 1990)	
Table 5-4.   Summary of variable costs per tonne soil (in US$, 1990)	
Table 5-5.   Total costs of extractive treatment per tonne soil (in US$, 1990)	
Table 6-1.   Sources of contamination at case study sites	
Table 6-2.   Principal contaminants at the Ville Mercier,  and the Lorentz Barrel and Drum sites.
Table 6-3.   Performance results for Ville Mercier, and Lorentz Barrel and Drum sites	
Table 6-4.   Performance results for Lot River site	
Table 6-5.   Ville Mercier operating costs, (x 1,000  CDN$)	
Table 6-6.   Estimated capital and operating costs associated with three  Ultroxฎ system units
            (in US$, 1990 )	
Table 6-7.   Lot River operating costs (in French francs)	
Table 8-1.   Costs of control techniques by levels of pollutant removal efficiency (in US$). .  .  ,
Table 9-1.   Stringfellow  Site technical studies	,
Table 9-2.   Stringfellow  Site treatability studies	
.  4
.  8
.  8
.  9
. 16
. 18
. 18
. 19
. 20
. 20
. 26
. 28
. 30
. 31
. 37

. 40
. 46
. 47
. 48
. 48
. 49
. 49
. 50
. 57
. 59
. 61
. 62
. 62
. 68
. 68
. 69
. 70
. 73

. 74
. 74
.94
102
102
                                                  XI

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Table 9-3.   Summary of remedial alternatives resulting from the Stringfellow Site feasibility
            study	105

Table 9-4.   Estimated cost comparison of revised remedial alternatives - overall site remedy	106
                                                 XII

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                                                                                                1
Introduction

Donald E. Banning
United States Environmental Protection Agency
Office of Research & Development, Cincinnati, Ohio 45268
United States

Robert F. Olfenbuttel
Waste Minimization and Treatment, BatteHe-Columbus Division
505 King Avenue, Columbus, Ohio 43201
United States
1.1   Background
   Ground water and soil contamination are among
the most complex and challenging environmental
problems faced by  most countries today.  This chal-
lenge results from a number of significant factors, such
as the complex geochemical, physical and biological
nature of contaminated subsurface soils and ground
water; limited knowledge regarding the behavior and
interaction of pollutants within these environmental
matrices; and the sheer magnitude of the contamina-
tion.  These factors, in turn, limit the application and
effectiveness  of conventional  waste  treatment tech-
nologies and result in high remediation costs.
   As a result, there is an ongoing need for more reli-
able,  cost-effective cleanup technologies to address
these problems and many governmental and private
organizations, in many countries, have committed
resources to  the development, test  and evaluation,
and demonstration of technologies to meet this need.
The ongoing challenge to these organizations is how
to maximize the value of these technology advance-
ments and effectively transfer the information to
people responsible for making decisions and im-
plementing remedial actions.
   Consequently, a NATO Committee on the Challen-
ges of Modern Society (NATO/CCMS) Pilot Study was
conducted from 1986 through 1991 for the purpose of
identifying and evaluating innovative, emerging, and
alternative remediation technologies, and transferring
technical performance and economic  information on
them to potential users. A specific and important ob-
jective  of the Study was to identify "lessons learned"
from the technology demonstrations, including not only
the successes but also those which illustrated technol-
ogy failures or limitations.  The latter type of informa-
tion  is rarely presented in conferences and/or
discussed in the technical  literature but is very impor-
tant for making informed decisions that involve critical
time and monetary requirements.  It is also useful for
defining priorities in research and development
programs.

1.2  Structure of the Study
   The Pilot Study Group  examined a total of 29 dif-
ferent remediation technology projects conducted by
non-NATO sponsored organizations, within member
countries, over the five year course of the  Study.
These  technologies treat, recycle, separate or con-
centrate contaminants in soil, sludges and ground
water matrices.  In  some  cases, such as for thermal
treatment, fixed facilities off-site  were studied, al-
though the emphasis was on in situ and on-site biologi-
cal, chemical/physical and thermal waste treatment
technologies.  The study did not include barrier walls
or technologies in which containment  was a primary
technique.

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  Chapter 1		

  1.2.1 Categories of the Technologies Examined
    For the purposes of this Study, three categories of
  technologies in various stages of development were
  examined with respect to  their possible use in the
  cleanup of polluted sites. They are:
    ซ Alternative technologies: A technology that is fully
      proven  in routine use for end-of-pipe treatment;
      however, performance and cost data is not readily
      available.

    ปInnovative technologies: A technology at the pilot
      or field scale for which performance or cost infor-
      mation is not complete, thereby impeding its use
      for remediation. In general, innovative technology
      requires field  testing to prove its  effectiveness
      before it is considered proven and available for
      use in remediation.

    "  Emerging technologies: A technology at a stage
     where successful bench  testing has been con-
     ducted and pilot-scale evaluation is now required
     to determine its potential for use in remediation
     (James and Banning 1989).

    The 29 technology projects  covering these
 categories served as a primary source for the discus-
 sion  and  results presented  in  this report.  However,
 this project-specific  information was supplemented by
 data from other sources, such  as Fellows of the
 NATO/CCMS, guest expert speakers at the interna-
 tional meetings of the Pilot Study, and the collective
 experiences and knowledge of the writers.  As such,
 the information provided in the following chapters rep-
 resents a synthesis  of all this information, not a com-
 pilation of the details of each project. In this way, the
 report serves as a  reference to the relative  state-of-
 the-technologies discussed.  It is not intended to be a
 manual on technology applications but as  a  guide to
 the potential application of technologies to various
 types of contamination.

 1.2.3  How the Technology Information is
      Presented
   Chapters 2 through 8 present the results of the Pilot
Study by technology area.  They include the following
technologies:
   ป Chapter  2: Thermal Technologies. This chapter
    discusses the  type and use of thermal tech-
    nologies  in various projects examined under the
    NATO/CCMS Pilot Study, both fixed facilities and
    transportable incineration systems.  Thermal
    processes  are  technologies designed to break
    down hazardous waste through either combustion
    or pyrolysis by exposure of the waste material to
    high temperature in a controlled environment.

  •Chapter 3: Stabilization/Solidification Tech-
    nologies.  In this chapter, a general description is
      given of cement based stabilization-solidification
      techniques.  Stabilization-solidification (S/S)
      refers to techniques that aim at preventing migra-
      tion of contaminated material into the environment
      by forming a solid mass.

    • Chapter 4: So/7 Vapor Extraction Technologies.
      Soil vapor extraction (SVE), also known as in situ
      venting (ISV), is a process that uses air to remove
      volatile organic compounds (VOC's) and some
      semivolatile organic compounds (SVOC's) from
      the vadose (unsaturated) zone.

    • Chapter 5: Physical Chemical  Extraction Tech-
      nologies.  A wide range of processes can fit within
      this broad category of technology.   Under this
      Pilot Study the following processes were chosen
      and are discussed in this chapter:  ex situ extrac-
      tion of organic and inorganic contaminants; in situ
     jet cutting followed by  oxidation of organic con-
     taminants; in situ acid extraction of heavy metals;
      and in situ electro-reclamation of heavy metals.

    • Chapter 6: Pump and Treat Ground Water. This
     chapter discusses the extraction of contaminated
     ground water from the subsurface,  followed by
     treatment of the water  at the  surface to remove
     the pollutants.  Treatment can  be by means of
     physical/chemical/biological technologies.

    • Chapter 7: Chemical Treatment of Contaminated
     Soils: APEG. This chapter discusses the chemi-
     cal dehalogenation of contaminated soils using an
     alkaline metal hydroxide with polyethylene glycol
     (APEG).  Processes of this type are applicable to
     soils and soil-like materials (after excavation) con-
     taminated with either aromatic or aliphatic
     chlorinated organic compounds, although the lat-
     ter require more rigorous treament conditions. It is
     of particular interest for the treament of soils con-
     taminated with polychlorinated biphenyls (PCB's).

   • Chapter 8: Microbial Treatment Technologies.  A
     large number of organic contaminants can be
     degraded by microorganisms.  This technology is
     discussed in terms of the basic biological soil
     remediation techniques of in situ biodegradation,
     landfarming and composting, and bioreactors.

   Each of the technology chapters is organized in the
following manner:
   • Introduction:  A description of the technology, in-
    cluding basic principles of the process and where
    it potentially can be applied.

   ป Case Studies Chosen: A summary of each of the
    projects evaluated, including why the project was
    chosen for evaluation. Available  details on each
    project are presented in Volume 2.

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                                                                                        Introduction
   • Background of the Case Study Sites as a Group:
    A synthesis of  pertinent information  from the
    projects that will help readers understand the
    range of the technology's application in these
    studies.  This includes the type, concentration
    and sources of contamination, type of soil/ground
    water matrices containing the contamination, and
    the main lessons learned, if any, in the application
    of the technology.

   • Performance Results:  An assessment of the
    results  from the case studies,  including whether
    project  objectives were met, whether the technol-
    ogy processes as a whole showed a common ef-
    fectiveness, and lessons learned, if any, in con-
    taminated site preparation and operational test-
    ing.

   • Residuals and Emissions: A discussion of multi-
    media residuals  and emissions, if any, associated
    with the technology processes that need attention
    when evaluating the potential application of these
    processes to contaminated sites.

   • Factors and Limitations to Consider for Determin-
    ing the Application of the Technology.  A sum-
    mary of important factors  limiting the application
    of the  technology processes including whether
    they are in situ or above ground techniques; type
    of  soils,  contaminants and contaminant con-
    centrations they can potentially treat; level  of
    cleanup they may be limited to; requirements for
    treatability/pilot studies; availability; etc.

   • Costs:  An overview of major capital,  operating
    and maintenance cost factors that need to be con-
    sidered by remediation planners; typical costs
    and/or  costs specific to case studies are given in
    some chapters.

   • Future Status of Case Study Processes and
    Technology as a Whole:  A summary of the state
    of the technology and its expected role in future
    site remediations.

   The process of selecting technologies for cleaning
up a complex hazardous waste site is a difficult, but
necessary process, and one in which countries use a
variety of approaches suitable for their needs. There-
fore, in  addition to  the technology discussions, a
separate chapter on Selecting Remedies at a Complex
Hazardous Waste Site is included (Chapter  9)  to
describe  the remedy selection process  used by the
United States Environmental Protection Agency (U.S.
EPA) and to examine remedial selection problems of
mutual concern for many countries.

1.2.4 Summary of Conclusions
   One  of  the major accomplishments of  this Pilot
Study is that  it demonstrated the need to exchange
technical and economic information on contaminated
land and ground water iremediation technologies.  It
resulted in an extensive set of conclusions regarding
specific technologies, remediation in general, technol-
ogy transfer and research needs. The conclusions are
based on the technology case studies examined
during the Study, as well as on expert speaker presen-
tations and special studies carried out by the Fellows
of the Pilot Study.
   The conclusions reached from this Study reveal
both the strengths and weaknesses of current tech-
nologies as well as what efforts are needed to increase
the effectiveness  of remediation tools and their ap-
plication. The conclusions are  summarized  in Table
1-1 and fully discussed in Chapter 10 on Conclusions
and Recommendations. Chapter 10 also provides the
recommendations  made by the Study members to the
NATO/CCMS Council for future actions by that or-
ganization.


   Insert Table 1-1
1.3   Contributions by CCMS Fellows
   The  Pilot Study was significantly aided by the
NATO/CCMS Fellowship program.  There were twelve
NATO Fellows associated with this Pilot Study.  Nine
Fellows conducted associated studies and submitted
project reports to the Pilot Study under guidance of the
Pilot Study Directors.  Three Fellows contributed to the
preparation of the Final  Report.  The Fellows repre-
sented private, university and governmental organiza-
tions in  Germany, Italy, The Netherlands, Turkey, the
United Kingdom,  and the United States. Their ac-
tivities covered the range of technologies evaluated
under the Pilot Study, including the development and
evaluation of biological treatment technologies; chemi-
cal destruction techniques; ground water behavior; and
the removal of toxic metals from soil and ground water.
Many of their reports have been and are planned to be
published in  professional journals.

1.4   Contents of Volume 2
   Volume 2 of this report contains appendices cover-
ing the following information:
   • Statements by the countries involved in this Pilot
     Study discussing their regulations and other over-
     view topics (Appendix 1 -A)

   • NATO/CCMS guest speakers' presentations (Ap-
     pendix 1-B)

   • Final reports by the NATO/CCMS Fellows (Ap-
     pendix 1-C)

   • Summaries and detailed information, when avail-
     able, on specific case  studies of projects ex-

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Chapter 1	

Table 1-1.  Conclusions for NATO/CCMS final report; demonstration of remedial action technologies for contaminated
            land and ground water.

 This tablo presents a summary of the conclusions arising from the Pilot Study.  They are first presented by specific technology
 areas represented by the chapters in this report; these are followed by general conclusions on remediation, technology transfer and
 research needs. These conclusions are based on the technology demonstration case studies as well as expert speaker
 presentations and special studies carried out by Fellows of the Pilot Study.  The numbering corresponds to paragraph numbers in
 Chapter 10.

 10.2       Specific Technology Area Conclusions
 10.2.1      Chapter 2:  Thermal Technologies
 10.2.1.1    Existing high temperature incineration (on- and off-site) successfully destroys organic contamination; however, not all
             nations allow its use for chlorinated compounds.
 10.2.1.2    LoW temperature thermal desorption is a  successful technology for treating volatile and semivolatile wastes.

 10.2.2      Chapter 3: Stabilization/Solidification IS/S) Technologies                            •
 10.2.2.1    S/S has been proven for the immobilization of most inorganics.
 10.2.2.2    Long term effectiveness data is not available.
 10.2.2.3    Scientifically based S/S leaching tests would provide a more easily comparable data base than is available today.

 10.2.3      Chapter 4:  Soil Vapor Extraction (SVEI Technologies
 10.2.3.1     SVE is a viable technology for unsaturated zone remediation of volatile and semivolatile contaminates.
 10.2.3.2    Off-gases can be treated by conventional technologies.

 10.2.4      Chapters:  Physical/Chemical Extraction  Technologies
 10.2.4.1     Conventional extractive techniques have limited in situ applications.
 10.2.4.2    Above ground extraction methods are powerful techniques.
 10.2.4.3    Etectroreclamation deserves to be extensively investigated.

 10.2.5      Chapter 6:  Pump and Treat Ground Water
 10.2.5.1     Pump and treat is a limited technology for remediating aquifers.
 10.2.5.2    Air stripping and activated carbon, as illustrated in this case study (i.e., Ville Mercier), were only partially effective
            treatment processes.
 10.2.5.3     An ultraviolet radiation/oxidation process (Ultrox)  was effective in reducing the concentration of volatile organics in
            ground water to acceptable levels.           ,          '                      .-•-..
 10.2.5.4   A precipitation process involving the use of lime and sodium sulfide was effective in reducing the concentrations of
            zinc and cadmium to acceptable levels.        •           ,                        ,..-',.

 10.2.6     Chapter 7: Chemical  Treatment of Contaminated Soils: APEG Treatment
 10.2.6.1    The long term stability and behavior of the products of partial dechlorination in APEG processes require investigation.
 10.2.6.2    The combination of thermal pyrolysis and  APEG treatment applied at Wide Beach, New York,  USA, was successful iri
            reducing PCB concentrations to below target cleanup levels.

 10.2.7     Chapter 8: Microbial Treatment Technologies
 10.2.7.1    Bioromodiation process scale-up from laboratory to the field is difficult.
 10.2.7.2    There is a need for both data on oxygen behavior  in the subsurface and improved methods of providing oxygen for in
            situ bioromodiation.
 10.2.7.3    There is a need for further  research on bioavailability and achievable concentrations.
 10.2.7.4    Soil inoculation has  not been proven to enhance in situ bioremediation.
 10.2.7.5    Permeability is a key factor in applying in situ bioremediation.

10.2.8      Chapter 9: Selecting Remedies at a Complex Hazardous Waste Site
10.2.8.1    Remediation  should strive to  be a complete solution.
10.2.8.2    Treatability studies must be conducted as  early as possible for effective remedy selection, and technologies should be
            judged  by their overall performance.

10.2.9      Appendix: In Situ Vitrification
10.2.9.1    Vitrification is a promising technique for treating mixed organic and inorganic wastes.

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                                                                                                        Introduction
Table  1-1. (Continued)
  10.3       General Conclusions
  10.3.1      Remediation
  10.3.1.1    Energy efficiency practices influence plant design and, therefore, processing costs in different countries.
  10.3.1.2    Treatment and permanent solutions are preferred.
  10.3.1.3    Integrated technology treatment systems are needed for site remediation.
  10.3.1.4    Field treatability/pilot studies should be conducted for each technology under consideratioin, under the range of
             potentially applicable site field conditions.
  10.3.1.5    Technology scale problems need to be addressed in design and testing.
  10.3.1.6    A mass balance approach to remediation is desirable.
  10.3.1.7    Technology remedies that transfer contaminants from one media to another should be avoided, if possible.
  10.3.1.8    All remediations require proper operation and management.
  10.3.1.9    Long term monitoring of permanent remediation may be necessary to ensure that cleanup goals are met.
  10.3.1.10  Basic records should be preserved.

  10.3.2     Technology Transfer
  10.3.2.1    Uniform data collection is needed.
  10.3.2.2    Independent technology evaluations are needed for effective technology transfer.
  10.3.2.3    The NATO/CCMS network is an important source  of information.

  10.3.3     Research
  10.3.3.1    There  is a continuing need for development of new technologies and use of common research protocols.
  10.3.3.2    Scientific understanding of processes is essential in order to ensure against formation of harmful end products.
  10.3.3.3    Standardization of analytical methods is needed.
  10.3.3.4    Techniques are needed to remove contamination beneath urban structures without significance disturbance to ongoing
             activities.
 REFERENCES
      James, S.C. and Sanning, D.E. Summary of the NATO/CCMS conference - The demonstration of remedial
      action technologies for contaminated land and ground water, in: Journal of the Air and Waste Manage-
      ment Association, Vol. 39, No. 9, September 1989, p.  1179.

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Thermal Technologies

Stephen C. James and Gregory L Stacy
United States Environmental Protection Agency
Office of Research & Development,  Cincinnati, Ohio 45268
United States
ABSTRACT

   Based on the site and waste characteristics of a site, thermal treatment may be most efficient. Thermal processes
are technologies/systems designed to break down hazardous waste through either combustion or pyrolysis by
exposure of the waste material to high temperature in a controlled environment. Thermal processes can, in a matter
of seconds, destroy waste materials that might otherwise not be able to be destroyed by natural or other treatment
processes.
   This chapter on thermal technologies discusses the type and use of thermal technologies and various projects
examined under the NATO/CCMS Pilot Study,  both fixed facilities and transportable incineration systems. In the
United States, the majority of fixed facilities are dedicated to the treatment of hazardous wastes generated and sent
to a facility for treatment. Transportable systems are primarily used for the cleanup of uncontrolled sites (Superfund
sites). While the United States intends to treat waste on site, many countries transport the contaminated material to
the hazardous waste treatment facility.
2.1   Introduction
   Hazardous waste thermal technologies have been
selected and implemented for remediation at many
contaminated sites.  This technology can be used for
the treatment of contaminated liquids, sludges, soils,
debris, and air streams. The most common incinera-
tion technology used is rotary kiln.  Other types of in-
cineration are  infrared  incineration, liquid injection,
hearth, fluidized  beds, circulating beds, pyrolysis
processes, plasma systems, and various kinds of in-
direct  heating systems.   Incineration is a proven
means of destruction for  many organic wastes and
should be considered as a possible treatment for the
cleanup of most toxic waste sites.
   An incineration system includes a number of  sub-
systems including the following:
   • Waste pretreatment
      • Waste  screening
      • Size reduction (grinding)
      • Waste  mixing
• Waste feed
   • Belt conveyers
   • Augers
   • Apron feeders
   • Hoppers
   • Chutes
   • Pumps (for liquids, sludges, oils)
   • Screw conveyers
   • Ram feeders
• Combustion unit
   • Rotary kiln or secondary combustion chamber
   • Liquid injection
   • Fluidized bed or circulating bed
   • Infrared
   • Thermal desorption
• Heat recovery (optional - not normally applicable
 to on-site, transportable incineration systems)

• Air pollution control equipment to treat
   • Products of incomplete combustion

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 Chapter 2	

         -  Minimized in combustion chamber and after-
           burner
         •  Afterburners can significantly reduce the
           toxicity of the  exhaust gas from an  in-
           cinerator
       •  Particulate emissions
         -  Venturi scrubber
         •  Wet electrostatic precipitator
         •  Electrostatic precipitator
         -  Quench systems
         -  Fabric filter
       • Acid gases
         -  Packed towers
         •  Spray towers
         •  Spray dryers
    ซ Residue handling and disposal
       • Ash
         - Solidification
         - Use  as fill material on-site, or dispose of it
          off-site
         • Scrubber water used to cool ash
       • Liquids
         - Neutralization
         - Filtration
         - Precipitation (metals)
         - Clarification
        - Carbon adsorption or air stripping (for small
          amounts of organics which are sometimes
          recovered in scrubber water)
        - Discharge to a municipal wastewater treat-
          ment system after successful pretreatment
          using one or more of the above options.
   Tables  2-1 and 2-2 list the number and capacities
of various hazardous waste incineration systems in the
United States and  hazardous waste incineration
facilities  in Europe.   Table 2-3 lists specific site data
from all U.S. projects.
   Rotary kiln Incinerators are slightly inclined (3
percent),  refractory-lined, rotating cylinders.   Their
primary use is  the combustion of organic solids and
sludges and other  contaminated  waste such as
product,  contaminated soils, and liquids with a high
heating value.   Rotary kiln incineration involves the
controlled  combustion of  organic waste under net

Table 2-1. Numbers and types of hazardous waste in-
          cineration facilities in the United States.
 Table 2-2. Hazardous waste incineration facilities in
           Europe.
Technology
Rotary kiln
Fluldlzod bed
Liquid injection
Hearth
Number of units
42
15
95
32
Company
INDAVER
Kommunekemi
SARP
SARP
TREDI
SIDIBEX
TREDI
GSB
ABR
ZSM
HIM
Broerius
Boskalis Esdex
ATM
AVR-Chemi
Eooteohniek II
NBM
Ecotechniek I
Cleanaway
Reohem
Location
Belgium, Antwerp
Denmark, Nyborg
France, Bassens
France, Limay
France, Salaise
France, Sandouville
France, St. Vulbas
Germany, Ebenhausen
Germany, Herten
Germany, Schwabach
Germany, Wiesbaden
The Netherlands, Barneveld
The Netherlands, Ijrnuiden
The Netherlands, Moerdijk
The Netherlands, Rotterdam
The Netherlands, Rotterdam
The Netherlands, Schiedam
The Netherlands, Utrecht
UK, Brentwood
UK, Pontypool
Capacity
(metric
tons/yr)
50,000
50,000
20,000
50,000
40,000
35,000
6,000
100,000
30,000
30,000
45,000
25,000
4,000
60,000
40,000
80,000
60,000
55,000
40,000
13,000
oxidizing conditions (the final oxygen concentration is
greater than zero).
   Wastes and auxiliary fuel are injected into the high
end  of the kiln and  passed through the combustion
zone as the kiln slowly rotates. Rotation of the com-
bustion chamber creates turbulence and improves the
degree of combustion.  Retention time in  the kiln can
vary from several minutes to an hour or more. Wastes
are substantially oxidized to gases and ash within the
combustion zone. Ash is removed at the lower end of
the kiln.  Flue gases  are passed through a secondary
combustion  chamber and then through air pollution
control units for paniculate and acid gas removal.
   The typical hazardous waste kiln is a cylinder with
an outside  diameter of 3 to 4  meters, an inside
diameter of 2.5 to 3 meters, and a length of 11 to  13
meters.  Typically, 5 tonnes of material will be charged
into the unit. Actual  loads will be determined by the

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Thermal Technologies
Table 2-3. Site data
Vendor
AET
Canonie
Canonie
Canonie
Canonie
Chemical Waste Mgt.
Ensoo
Ensco
Ensco
Ensco
Ensco
Ensco
GDC Engineering
Harmon
Harmon
Harmon
IT Corporation
IT Corporation
IT Corporation
IT Corporation
Kimmins
Ogden
Ogden
Ogden
O.H. Materials
O.H. Materials
O.H. Materials
O.H. Materials
O.H. Materials
O.H. Materials
O.H. Materials
from U.S. hazardous
Site Name
Valdez
Ottati & Goss
Canon
South Kearny
McKin
confidential
Union Carbide
Lenz Oil
Sydney Mines
NCBC
Bridgeport
Smithville
Rubicon
Bog Creek
confidential
Prentiss
Motco
Cornhusker
AAP
Louisiana AAP
Sikes Pits
La Salle
confidential
Swanson River
Stockton
Goose Bay
Gas station
Rail yard
Twin City AAP
Rail yard
Florida Steel
Rail yard
waste incinerator projects.
Site Location
Valdez, Alaska
Kingston, New Hampshire
Bridgewater, Massachusetts
South Kearny, New Jersey
Gray, Maine
northeast, United States
Seadrift, Texas
Lemont, Illinois
Brandon, Florida
Gulfport, Mississippi
Bridgeport, New Jersey
Canada
Geismar, Louisiana
Howell Twp., New Jersey
Alabama
Prentiss, Mississippi
Lamarque, Texas
Grand Island, Nebraska
Minden, Louisiana
Crosby, Texas
La Salle, Illinois
Sacramento, California
Kenai, Alaska
Stockton, California
Goose Bay, Canada
Cocoa, Florida
Pennsylvania
New Brighton, Minnesota
Pennsylvania
Indianatown, Florida
Cleveland, Ohio

Source of
Contamination
Crude oil spill
Solvent treatment
Solvent recycling
Solvent recycling
Waste treatment &
disposal
PCB spills
Chemical manufacturing
Waste oil
Waste oil lagoon
Herbicide storage
Used oil recycling
PCB transformer leaks
Chemical manufacturing
Paint/solvent disposail
Gasoline tank leak
Wood treatment
Styrene tar disposal pits
Munitions plant pits
Munitions plant lagoon
Chemical waste pits
PCB capacitor
manufacturing
Town gas site
Oil pipeline compressor
oil
Underground tank oil
leak
PCB's
Petroleum tank leak
Repetitive spills
Munitions plant
Diesel tank spill
Steel mill used oils
Refueling station

Project
Status
Finished
Finished
Contracted
Finished
Finished
Contracted
Contracted
Finished
Finished
Finished
Ongoing
Contracted
Ongoing
Ongoing
Finished
Finished
Ongoing
Finished
Finished
Contracted
Contracted
Contracted
Ongoing !
Ongoing
Ongoing
Finished
Finished
Finished
Finished
Finished
Finished

Site Size
(tonnes)

7,200
5,900
16,300
1 6,300
31,800

23,600
9,100
20,000
90,700
' 6,350
47,200
20,400
540
8,300
72.6OO
40,800
90,700
309,400
62,600
20,400
72,600
14,500
3,600
900
1,400
1,800
1,200
16,300
1 ,400

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  Chapter 2
Table 2-3. (Continued)
Vendor
Sito Rocl. Systems
Site Rocl. Systems
Sito Rocl. Systems
Soil Remediation Co.
SoilToch
TOI Services
Thermodynamics Corp.
U.S. Waste Thermal
Processes
U.S. Waste Thermal
Processes
U.S. Waste Thermal
Processes
Vortac site contractors
Vesta
Vesta
Vesta
Vesta
Vesta
Wostinghouso/
Haztoch
Wostinghouso/
Haztoeh
Woston
Woston
Woston
Woston
Woston
Site Name
Koch Chemical
Gulf Oil
Sun Oil
multiple sites
Waukegan
Harbor
Chevron
S. Crop
Services
gas station
confidential
confidential
Vertac
Nyanza
Rocky Boy
S. Crop Service
Am. Crossarhn
Fort A.P. Hill
Peak Oil
La Salle
Revenue
Letterkenny
Tinker AFB
Paxton Avenue
Lauder Salvage
Site Location
Kansas
multi-sites
multi-sites. South Carolina
multi-sites
Waukegan, Illinois
El Segundo, California
Delray Beach, Florida
Temecula, California
California
San Bernadino, California
Jacksonville, Arkansas
Ashland, Massachusetts
Havre, Montana
Delray Beach, Florida
Chehalis, Washington
Bowling Green, Virginia
Tampa, Florida
La Salle, Illinois
Springfield, Illinois
Chambersburg, Pennsylvania
Oklahoma City, Oklahoma
Chicago, Illinois
Beardstown, Illinois
Source of
Contamination
Tank bottoms
Oil spills
Oil spills
Gas and oil leaks/spills
Marine motor
manufacturing
API sludges
Crop dusting operation
Petroleum tank leak
Oil spills
Oil spills
Chemical manufacturing
Dye manufacturing
Wood treatment
Crop dusting operation
Wood treatment
Army base
Used oil recycling
Transformer
reconditioning

Army depot
Air Force base
Waste lagoon
Metal scrap salvage
Project
Status
Contracted
Contracted
Contracted
Finished
Contracted
Contracted
Finished
Finished
Contracted
Finished
Contracted
Finished
Ongoing
Finished
Finished
Finished
Finished
Finished
Finished
Finished
Finished
Ongoing
Finished
Site Size
(tonnes)
600
16,300

2,700
18,100
27,200
1,600
,900
6,800
490
5,900
900
1,600
1,600
800
180
6,350
27,200
900
450
900
14,500
7,700
thermal input to the kiln rather than the mass load.
The heat source is either a hazardous waste or an oil
or natural gas flame directed  axially down the kiln.
The typical hazardous waste secondary chamber is
sized sufficiently to achieve a 2 second residence time
for combustion gases at 2,200 *C.
   Electric Infrared Incineration systems use silicon
carbide  elements to generate thermal  radiation
beyond the red end of the  visible spectrum. Waste to
be treated passes through the unit on a noncorrosive
steel belt and are exposed to the heat generated  by
the radiation.  Organics are driven from the waste
material.  Off-gases pass into a secondary chamber
that is heated via supplemental gas or fuel oil for com-
plete destruction of the organics.   Flue gases are
treated by a scrubber system and the residual ash is
collected for further treatment and/or disposal.  Normal
operating temperatures are  1,600 to 1,800 ฐC in the
                                                 10

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                                                                                Thermal Technologies
primary chamber and 1,900 to 2,200 ฐC in the secon-
dary chamber.
   Fluidized bed incinerators consist of a refractory-
lined vessel containing a bed of inert, granular, sand-
like  material.  In operation, combustion  air is forced
upward through the bed, which fluidizes the material at
a minimum critical velocity. The heating value of the
waste plus any auxiliary fuel maintains a desired com-
bustion temperature in the vessel.  The heat of com-
bustion is transferred back into the bed, and the
agitated mixture of waste, fuel, and hot bed material in
the presence of fluidizing  air provides a combustion
environment that resists fluctuations  in  temperature
and retention time due to moisture, ash, or Btu content
of the waste.
   A variation of the fluidized bed is the circulating
fluidized-bed (CFB) combustor.  This process uses
higher air velocity and circulating solids to create a
larger and highly turbulent combustion zone for the ef-
ficient  destruction of  organics  and the  retention of
resultant acid vapors.  The key to this combustion
technology is the  hydrodynamic behavior of the
fluidized bed. Conventional fluidized beds are general-
ly well understood.   They are characterized by the
clearly defined gas bubbles. Units of this  type operate
at gas  velocities of 2 to 3 m/s (depending on particle
size).  The  main difference  between  circulating and
fluidized beds  is the gas velocity.  CFB's operate at
gas velocities from 5 to 10 m/s.  These gas velocities
give  rise to rapid carry over of solids from the top of the
vessel.  In order to replenish solids in  the vessel, the
CFB systems have developed a solids  separation and
return loop. This enables the bed material to be in
constant contact with the waste material.
   Fluidized bed technology can be operated at lower
temperatures than other thermal systems because of
the high  mixing energies aiding the  combustion
process.  This mixing  offers  high thermal efficiency
while minimizing auxiliary  fuel requirements and
volatile metal emissions.
   Liquid-injection  incineration systems are usually
refractory-lined chambers  (horizontal, vertical  up or
down), generally cylindrical, and equipped with a
primary combustion and  secondary  chamber.  The
waste is burned directly in a burner or injected into the
flame zone or combustion zone of  the incinerator
chamber through nozzles.  Critical to the  operation of
this type of incineration system is the atomizing nozzle
used to convert the  liquid stream into finely atomized
droplets.
   Multiple-hearth incinerators are used for destroy-
ing solids  and  heavy sludges. Waste material enters
the combustion chamber at the top and drops through
a series of  refractory hearths until noncombustible
residues fall to the bottom of the unit.  This method is
useful for the recovery of metals from the waste feed.
Plasma systems use a plasma-arc device to create ex-
tremely high temperatures (25,000 'C).  Gaseous
emissions (primarily hydrogen and carbon monoxide),
acid gases in the scrubber, and ash components in the'
scrubber water are the residuals. These systems are
applicable to liquid waste only because of the injection
systems employed.
   In situ vitrification (ISV) uses an electric current to
melt soil or sludge at extremely high temperatures of
1,600 to 2,000 ฐC. This destroys organic pollutants by
pyrolysis.  Inorganic pollutants are incorporated within
the glass-like vitrified mass.  Water vapor and organic
pyrolysis by-products are captured in a hood,  which
draws the contaminants  into an off-gas treatment sys-
tem that removes particulates and other pollutants.
   The vitrification process begins by inserting large
electrodes  into contaminated zones  containing suffi-
cient soil to support the formation of a melt.  An arran-
gement (usually square)  of four electrodes is placed to
the  desired treatment  depth in  the volume  to be
treated. Because soil typically has low electrical con-
ductivity, flaked graphite and glass frit are placed on
the soil surface between the electrodes to  provide a
starter path for electric current.  The electric current
passes through the electrodes and begins to melt soil
at the surface. As power is applied, the melt continues
to grow downward, at a rale of 2.54 to 5.08  cm/h. In-
dividual settings (each single placement of electrodes)
may grow to encompass a total melt mass of 907 ton-
nes and a maximum width of 10.7 meters. Single-set-
ting  depths as great as 7.6 meters are considered
possible.
   Depths exceeding 5.8 meters have been achieved
with the existing large-scale ISV equipment.  Adjacent
settings can be positioned to fuse to each other and to
completely  process the desired volume at a site.
Stacked settings to reach deep contamination are also
possible. The large-scale ISV system melts soil at a
rate  of 3.6 to 5.4 tonne/h.   Because the void volume
present in paniculate  materials  (20 to 40 percent for
typical soils) is  removed during processing, a cor-
responding volume reduction occurs.  After cooling, a
vitrified monolith results,  with a silicate glass and
microcrystalline structure.   This monolith possesses
structural and environmental properties.

2.2   Case Studies Chosen
   The following discussion summarizes the thermal
projects in this NATO/CCMS Pilot Study by participat-
ing countries.

2.2.1  Case Study 2-A:  Rotary Kiln Incineration,
      The Netherlands
   A national inventory taken in 1981  revealed that the
soil contamination problem in The Netherlands was far
greater than was  first thought.   The survey identified
about 4,000 cases of possible soil contamination.
However, this figure has since risen to around 7,500.
                                                  11

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 Chapter 2
 Since 1982, much experience has been gained with
 soil cleanup techniques.  In particular, thermal and ex-
 traction processes passed the technological develop-
 ment stage and are applied on a large scale for various
 types of soil contamination.
    Ecotechniek has two thermal soil treatment plants,
 one In Utrecht, and one near Rotterdam. The latter
 installation  has a  maximum treatment capacity of 50
 metric tons per hour. The contaminated soil is treated
 in the rotary kiln by direct heating at a temperature of
 up to 550 ฐC  with a residence  time of about 7-15
 minutes.  The resulting vapors are afterburned at  a
 temperature of 850-1,000 ฐC and  a residence time of
 1-2 seconds.   The afterburner limits the emission of
 hydrocarbons, CO, and HCN. Heat exchangers permit
 the reuse of the energy released. Measures to limit
 emission include a wet scrubber (SO2)  and a fabric fil-
 ter (dust).  The wash water from  the wet scrubber is
 cleaned and partly recycled for cooling the  cleaned
 soil.  The  process is suitable for the removal  of
 aromatic and aliphatic hydrocarbons  (up to 10,000
 mg/kg), cyanides (up to 400 mg/kg), and polynuclear
 aromatic hydrocarbons (PAHs) (up to 800 mg/kg).
    The installation is suitable for all types of soil. It is
 especially the moisture content, the organically-bound
 nitrogen and sulfur content of the soil, and the type of
 contamination that influence the costs. These vary be-
 tween Dfl 100 and Dfl 190 per metric ton. (One Dfl is
 approximately U.S. $0.5, October 1987.)
    To date, much experience has  been gained for the
 treatment of contaminated soil from former gasworks
 sites and soil contaminated by leaking fuel tanks.  A
 trial cleanup of soil contaminated with  chlorinated
 hydrocarbons is planned.  The treatment of two  types
 of soil have been evaluated  in particular with respect
 to:
   • "Easy to  clean" soils:  sandy soil, chiefly con-
     taminated with cyanides and polynuclear aromatic
     hydrocarbons (PAHs), derived from a former gas-
     works site; and

   ซ"Difficult to clean"  soils:  clayish soil  and rubble,
     chiefly contaminated with PAHs and mineral oil,
     derived from  a site  where various wastes had
     been dumped.
   They were evaluated with respect to cleanup of the
 soil and air emission during the treatment.
   The results showed that residual concentrations of
 mineral oil and cyanides amply met the requirements
 for both types of soil. For some of the PAHs, the quite
 strict requirements were  not met  for soil originating
 from the dump site. In the case of the  gasworks soil,
 higher residual concentrations of (Borneff) PAHs were
 allowed. As expected, no removal of heavy metals
took place.
    The results of air pollution monitoring show that the
 requirements set for emissions onto the air were met
 during the treatment of both types of soil.  (For more
 information on this project, see Appendix 2-A.)
 2.2.2 Case Study 2-B:  Indirect Heating in a Rotary
      Kiln, Germany
    The Ruhr Valley of Germany has several former
 gasworks and coking plants.  Contamination at these
 sites is due to process waste as well as spills. The soil
 is contaminated with aromatic and aliphatic hydrocar-
 bons. The site at Unna-Boenen is a former coke oven
 plant with an area of 250,000 m2. The site is divided
 into three areas:  coal area site, coking oven site, and
 acid resin storage.  Volatile  organic  compounds
 (VOC's) may be as high as 5 percent of the waste by
 weight.   Other contaminants  such as pesticides,
 PCB's, and heavy metals are present up to 1 percent
 by weight of the soil. In addition to the examination of
 various technologies for the cleanup of the site, an in-
 direct thermal heating technology was investigated.
   This system, designed by Ruhrkohle  Urnwelttech-
 nik of Unna Boenen (Germany),  is based on a closed-
 cycle indirect  thermal treatment (pyrolysis) process.
 Treatment of contaminated soil begins with mechani-
 cal crushing of the soil (to a maximum size of 50 mm).
 The crushed soil is stored in a feed hopper and travels
 from the hopper to the kiln by means of a double helix
 screw conveyer.  This permanently filled conveyer
 seals the  kiln system at approximately  1.5  mbar
 depression, which prevents the escape of dust or
 pyrolysis gas.  The crushed soil then passes through a
 rotary kiln 22 meters in length.  In the kiln, tempera-
 tures between 450 and 600  ฐC  release  volatile
 material.   Temperatures  are obtained by heating the
 outer shell of  the  rotary kiln with  18  natural gas
 burners. Water cools the treated soil that is returned to
 the original site.   Post-combustion  of the  released
 gases occurs in a secondary chamber.  In this cham-
 ber temperatures reach a maximum of 1,300 ฐC. After
 quenching and scrubbing, the gas exits through the ex-
 haust stack.
   The system was completed in May 1988 and began
 shakedown in July. Over 2,720 tonnes of soil have
 been decontaminated in  the trial testing.  The effec-
tiveness  of the soil decontamination increased  for
grain sizes less than 50 mm in diameter.  Operational
problems with the ash removal screw, which resulted
 in overheating of the ash  removal system and sub-
sequent obstruction, have been corrected. The design
of the plant enables it to be transported and reused at
different locations.  The operators planned full-time
operation of the system with the ability to process ap-
proximately 45,360 tonnes of contaminated soil per
year. (For more information on  this project, see Ap-
pendix 2-B.)
                                                 12

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                                                                               Thermal Technologies
2.2.3  Case Study 2-C: Off-site Soil Treatment,
      Japan
   The electro-chemical industrial facility was used
from 1917 to 1979 primarily for the production of soap,
bleaching powder, hydrogen chloride, organic com-
pounds, and, later, sodium hydroxide. It is located in a
residential area in Tokyo and is highly contaminated
with mercury and lead; this contamination was  dis-
covered in 1979 when the company stopped operation
and dismantled the facility in order to relocate the fac-
tory. The mercury contamination was generally limited
to the surface soils with an average concentration of
36,800 ppm (maximum concentration  of 156,000
ppm). About 56,000 m? of contaminated soil with mer-
cury levels above 2 mg/kg were required to be treated
before redevelopment of the site could occur. Based
on the level of mercury contamination, off-site thermal
treatment and on-site containment processes were
selected. All soils with mercury levels above 10 mg/kg
were to be sent off-site for incineration. All other soils
below this level were treated on-site using  immobi-
lization and containment.
   About 6,000 drums of contaminated soils were sent
to the Nomura Kosan Co., a firm specializing  in the
refining of mercury. Cost of the thermal treatment was
US$330/tonne  plus a  transportation cost of
US$81/tonne.  The treatment facility is equipped with a
vertical multistage rotary furnace called a Herreshoff
Furnace. The mercury contaminated soil  was treated
at temperatures from 600 to 800 ฐC. Volatile mercury
vapors were  condensed on the inner wall of a con-
denser.  Crude mercury was recovered from the soot
and refined  into a commercial grade product with a
purity of  99.99 percent.  Slag from the furnace was
placed in an on-site secure landfill. Trace amounts of
mercury and acid gas components in the flue gas were
removed from the exhaust gas by adsorption  and
neutralization. (For more information  on  this project,
see Appendix 2-C.)

2.2.4  Case Study 2-D: Electric Infrared
      Incineration, United States
    Beginning in the 1950's,  Peak Oil, an oil refiner,
operated a used-oil processing facility  in Brandon,
Florida.  Various  waste streams from the  refining
operation were dumped into a natural lagoon located
on the property.  The lagoon quickly became con-
taminated with PCB's and lead from the waste
material. This led to the contamination of the shallow
aquifer system that was the source of the local drinking
water supply. Because of the continuing contamination
of the aquifer from the lagoon, the United States En-
vironmental Protection Agency (U.S. EPA) initiated a
project to remove the contents of the  lagoon and the
contaminated soil under and around the lagoon. This
amounted to approximately 7,000 tonnes of sludge
and soil contaminated with  PCB's and lead.
   The U.S. EPA selected electric infrared incineration
for the cleanup operation.  In November 1986, a
transportable unit was brought to the site on five
separate  trailers.  Once on-site, the units were con-
nected together on new  or existing concrete pads
prepared for the cleanup operations. The connected
components formed the 22-meter long primary Com-
bustion unit (PCC), the 24-meter long secondary com-
bustion unit (SCC), an emission control system, and a
process management and monitoring center.
   Electric infrared incineration technology (originally
developed by Shirco Infrared Systems,  Inc. of Dallas,
Texas) is a mobile thermal processing system that
uses electrically powered silicon carbide rods to
generate heat for volatilization of organics from waste
in the primary incineration chamber. Waste is fed into
the primary chamber on a wire mesh belt and exposed
to temperatures up to 1010 ฐC by the infrared radiant
heat. Ash material from the primary is quenched and
gas  emissions are put through a control  system  for
neutralization and paniculate  removal.  Technology
demonstrations  were conducted on the full and pilot-
scale units at two Superfund  sites:  Peak Oil site in
Florida and  Rose Township site in  Michigan.  Both
sites contained PCB's arid high concentrations of lead.
In both cases, testing and "evaluation proved that the
technology could successfully destroy PCB's; the sys-
tem  achieved greater than 99.99  percent DRE's
(destruction and removal efficiencies). In addition, the
system was tested for its ability to retain and fix lead in
the ash.  the lead in the  ash was not fixed since it
could be easily  removed via leach testing.  This was
determined by  the Toxicity Characteristic Leaching
Procedure (TCLP) which is a United States testing pro-
cedure.
   This technology is applicable for  the treatment of
organic contaminants contained in soils  or sludges.
Since the waste is fed into and through the system on
a wire mesh belt, only solid material can be processed
through the unit.  Liquid organic wastes can only be
handled if they are mixed with a solid material before
processing.
   Testing has demonstrated the ability of the'electric
infrared incineration technology to:
   • Achieve organic destruction greater than the
     Resource Conservation and Recovery Act
     (RCRA) standard of 99.99 percent ORE

   • Achieve destruction of dioxins and furans greater
     than the RCRA standard of 99.9999 percent ORE

   • Achieve  destruction  of PCB's greater than the
     Toxic Substances Control Act (TSCA) standard of
     99.9999 percent

   • Achieved HCl RCRA  performance standard of 99
     percent removal
                                                 13

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  Chapter 2
    ป Achieved RCRA paniculate emission standard of
      180 mg/dscm (dry standard cubic meters).

    (For more information on this project, see Appendix
 2-D.)

 2.2.5 Case Study 2-E: In Situ Vitrification, United
       States
    In-situ vitrification (ISV) involves the in-situ melting
 of contaminated solids  in soils. An array of four
 electrodes  is placed to the desired treatment depth.
 As current  flows through the soil, it is heated to the
 melting temperature of the soil (typically 1600-2000
 ฐC). Once molten, the mass becomes the primary con-
 ductor and heat transfer medium, allowing the process
 to continue. The  molten mass grows downwards and
 horizontally as long as power is applied. A recent test
 treated a zone 8  m (27 ft) square by about 6 m (20 ft)
 deep (about 900 tonnes  at a bulk  density of 2,200
 kg/m3) and took 7 to 10 days to complete. The treated
 mass takes several months to a year or more to cool,
 although the collection hood can be removed after a
 few hours. Once  one setting Is completed, the equip-
 ment Is moved to  an adjacent area; neighbouring
 blocks will fuse together. The  process may be applied
 to contaminated natural soils, but also to other natural-
 ly occurring soil-like materials and solid process was-
 tes, Including slits, sediments,  sludges and tailings.
   As a result of the ISV process, individual con-
 taminants may:
   ซ Undergo chemical and/or thermal destruction

   • Enter the off-gases from  which they can then be
     removed

   ป Be chemically or physically Incorporated into the
     resultant solid product.
   In tests  at various scales, it is claimed that the
 process is  applicable to  soils  containing volatiles,
 semf-volatlles, and refractory (non-volatile) organic
 compounds  and inorganics (heavy metals), a variety of
 radioactive  materials, and a broad range of  combus-
 tible, metallic, and inorganic scrap  materials  (e.g.
 paper, plastic, wood, drums, concrete, rock, asphalt). It
 is also claimed that drummed  organic wastes can be
 treated.
   The ISV process results  in a  20 to 40 precent
 reduction in  volume for typical soils. Once processing
 is completed, clean backfill is placed over the residual
 monolith to  restore  site  levels. As cooling continues
 additional subsidence may occur.
   In  the United  States this technology  is available
from only one commercial vendor (Geosafe Corpora-
tion) and has been under development by Battelle
 Memorial Institute since 1980. However, the main
clean-up project that the technology was to  comple-
ment could  not go ahead because the vendor of the
technology withdrew it from the market. This  decision
 was prompted by an accident that occurred in March
 1991 during large scale testing which resulted in a fire
 and destruction  of some equipment. The company
 took the view that although the accident "involved only
 non-hazardous materials,.. such an event could have
 unacceptable  consequences if it were to happen at a
 hazardous waste site." The company did "not consider
 it prudent to  proceed with commercial large-scale
 operations if there is any reasonable chance of recur-
 rence of this event.." However, some work is continu-
 ing  with the U.S. Department of Energy.  (For more
 information on in situ vitrification, see Appendix 1-C.)

 2.3   Background of the Case Studies as a
       Group
   Thermal treatment has been used for many years
 to treat a variety of waste products generated from the
 manufacturing of products.  Over the last several
 years, thermal treatment has been used widely in the
 cleanup of remediation sites.  Primarily, this technol-
 ogy has been used in the treatment of  contaminated
 soils, sludges  and sediments; in addition it is some-
 times used to treat liquids.  Principally, this technology
 Is used to treat organic contamination. However, one
 case study  reports on  the recovery of  mercury from
 contaminated soil.
   The case studies represent a cross  section  of
 problems that  may be  found at sites throughout any
 country and also represent thermal technologies that
 are currently available.  Three case studies (Germany,
 The Netherlands and United States)  report on
 problems that are very common to all countries.
 These case studies  represent the treatment of
 aromatic and aliphatic hydrocarbons (former gasworks
 site), waste oil contaminated with PCB's (former waste
 oil refiner), and various other organic contamination
 that was improperly disposed of at these facilities. As
 can be seen from the results, thermal treatment offers
 a very high  level of destruction of the organic waste.
 The other case study (Japan) discusses the removal of
 mercury from  soil from a former electro-chemical
 facility.
   In each case study, defined cleanup goals were
 met. However data on the effectiveness of each case
 study varies widely.  Very  little  information was
 provided on waste feed preprocessing or  residual han-
 dling. Cost information that documented  the complete
 cost  of using thermal technologies was also missing.
 More information on performance and costs  are
 needed to accurately assess the technology overall.

 2.4   Performance Results
   When properly  designed, constructed  and
operated, thermal technologies should be able to treat
waste to appropriate regulatory levels while address-
                                                 14

-------
                                                                                Thermal Technologies
 ing other technical issues and operating as a cost-
 effective unit.
   General examination of performance data for ther-
 mal technologies indicate that various types of system
 problems occur.  One parameter which usually affects
 the performance of a thermal unit is the compatibility of
 the feed with the feed system.   The feed system can
 consist of belt conveyors, augers, hoppers, chutes,
 pumps, screw conveyors, and ram systems.  The feed
 system must be reliable and capable of continuous
 operation even when the feed varies widely in size,
 density, moisture content, and  other properties.  The
 feed system must also be capable of reducing the size
 of the incoming feed if necessary and must be reliable.
 If this is not the case, both the  technical performance
 of the unit and the projected cost to operate the unit
 will be affected. A feed system which constantly fails
 or can not produce the projected throughput to the
 thermal  unit will adversely affect  the  project.   In
 general, problems of this nature will lengthen the time
 to complete the job and this will negatively affect the
 project economics.
   In addition to the feed system, other operating con-
 ditions that can have impact on the operation of the
 unit are: waste pretreatment; type of combustion unit;
 air pollution  control equipment  used to treat-products
 of incomplete combustion, paniculate emissions, and
 acid gases; and residue handling and disposal for both
 ash and liquids.
   Results from the NATO/CCMS case studies  show
 that soils of smaller grain sizes  are the most success-
 ful.   Also, transportation (either moving a mobile in-
 cinerator system to the  site or  transporting the waste
 feed to an off-site incinerator) is  critical in the selection,
 efficiency, and economics of a system.  Most of the
 case studies discussed obtained  a destruction and
 removal efficiency  of 99.99 percent.  In addition to
 these results, Table 2-4 shows design  and operating
 parameters and performance data for various thermal
 units in the United States; see also Table 2-3 for more
 site information on these projects.

 2.5   Residuals  and Emissions
   Actions undertaken  to remediate a site using in-
 cineration or to operate a hazardous waste incinera-
tion facility must  meet specific performance and
 regulatory requirements and will require monitoring to
 assure compliance.  The following may be required to
 protect human health and the environment:
  • Performance, design,  or action-specific require-
    ments such as air emission standards, water dis-
    charge  standards, and land disposal require-
    ments for the ash.  In general, each country has
    developed their own standards for this category.

  •Ambient/chemical-specific requirements which
    set health risk-based concentration limits based
     on emission limits and ambient air quality stand-
     ards.

   • Other regulatory (local) requirements that pertain
     to the construction or operation of such an in-
     cineration system.

   Incineration systems will also require monitoring to
 assure  compliance with any regulatory requirements
 that have been imposed on the operation of the sys-
 tem.  Incineration systems will generally be required to
 perform continuous monitoring for CO and NOx. In ad-
 dition, continuous monitoring will generally be required
 for combustion temperature (primary and secondary
 chamber), waste feed rate, SOa, particulates, HCI, and
 various other parameters based on the waste feed and
 on permit requirements.
   Under RCRA in the United States, standards for in-
 cinerator performance include:
   • Principal organic hazardous constituents (POHC)
     of each waste feed must be destroyed and/or
     removed to a removal efficiency (ORE) of 99.99
     percent.  These hazardous organics are the most
     abundant and most difficult to burn.  Dioxins and
     RGB's must achieve a ORE of 99.9999 percent.

   • Particulate emissions must not exceed  180
     mg/dscm, corrected to 7 percent  oxygen in the
     stack gas.

   • Gaseous hydrogen chloride (HCI) emissions must
     be  controlled to a maximum of 8.8 kg/h, or be
     removed to 99 percent efficiency.

   RCRA standards for incinerator operation, monitor-
 ing, and inspection, as well as procedures for granting
 permits are also specified.  Incinerator owners  and
 operators must also comply with general facility stand-
 ards and administrative requirements for all hazardous
 waste management facilities.  In  the United States,
 many states also have their own standards which are
 more stringent than the national RCRA standards. In
 this situation  the more stringent standards  must be
 met.
   Compliance with the above  specifications and re-
 quirements is determined by incinerator performance
 during trial burns or duringi probationary operation.
 This operation also determines the incinerator's perfor-
 mance and the optimal operating conditions.
   The collected data is then  submitted to  the U.S.
 EPA with the application for permit. After review by
the U.S. EPA and by state agencies, a RCRA permit is
developed.  The  permit establishes operating require-
 ments, standards for carbon monoxide in the stack ex-
 haust gas, waste feed rate, combustion temperature,
 and combustion gas flow rate. The permissible values
of each  of these may be unique to each incinerator.
 Performance data submitted by the applicant ensures
                                                 15

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Chapter 2
Table 2-4. Performance data for various U





Vendor
AET

Cnnonio
Canonie
Canonie
Canonie
Choniical Waste
Mgt
Ensco
Ensco
Ensco
Ensco
Ensco
Ensco
GDC Engineering
Harmon
Harmon

Harmon
IT Corporation
IT Corporation
IT Corporation
IT Corporation
Kimmins
Ogdon
Ogden
Ogden
O. H. Materials
O. H. Materials

O. H. Materials
O. H. Materials
O. H. Materials
O. H. Materials
O. H. Materials

Site Reel. Sys.
Site Rocl. Sys.

Site Reel. Sys.
Soil Romod. Co.

SoilTooh





Site name
Valdez

Ottati & Goss
Canon Bridgewater
South Kearny
McKin
confidential

Union Carbide
Lenz Oil
Sydney Mines
NCBC
Bridgeport Rental
Smithville
Rubicon
Bog Creek
confidential

Prentiss Creosote
Motco
Cornhusker AAP
Louisiana AAP
Sikes Pits
La Salle
confidential
Swanson River
Stockton
Goose Bay
gas station

rail yard
Twin City AAP
rail yard
Florida Steel
rail yard

Koch Chemical
Gulf Oil

Sun Oil
multiple sites

Waukegan Harbor
,S. hazardous waste





Indicator compound
Petroleum
hydrocarbons
Volatile organics
Total VOC
Volatile organics
Trichloroethylene
PCB's


Hydrocarbons
Hydrocarbons
Dioxin
PCB's
PCB's


Petroleum
hydrocarbons
PAH's
PCB's
Trinitrotoluene
Trinitrotoluene
Total PNA's
PCB's

PCB's
Total hydrocarbons
PCB's
Benzene, toluene.
xylene
Diesel oil
PCB's
Diesel oil
PCB's
Petroleum
hydrocarbons
Toluene, xylene
Benzene, toluene.
xylene

Petroleum
hydrocarbons
PCB's
incinerator projects.
Contam-
inant
cone, in
treated
soil
(mg/k)


<0.2
<0.1

<0.1
<2.0


<5.0
<5.0
<15




<100

<2
"
<1.3
<1.3
<100
<2.0

<0.1
<1

<0.1

<100
<2
<100
<2
<50


<0.1


<50




Particulate
Trial emissions
burn (mg/dNm3
required @7% C)2)


Yes <69
No
No
Yes <69


Yes
Yes 14
No
Yes 39
Yes
Yes
Yes
Yes 34
No

Yes 25
Yes
Yes 39
Yes
Yes <183
Yes

Yes < 1 1 4
Yes <183
Yes
Yes 25


No

Yes 1 28
Yes 89


No




Yes




RCRA
permit


No
No
No
No


Yes





No

No

No
No
No
No
No
No

No
No
No
No


No

No
No


No


No

No




TSCA
permit


No
No
No
No








No
No
No

No
No
No
No
No
No

Yes
No
Yes
No


Yes

Yes
No


No


No

No
                                            16

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                                                                                  Thermal Technologies
Table 2-4. (Continued)
  Vendor	

  TDI Services
  Thermodynamics
   Corp.
  U.S. Waste
   Thermal Proc.
  U.S. Waste
   Thermal Proc.
  U.S. Waste
   Thermal Proc.
  Vertac site
   contractors
  Vesta
  Vesta
  Vesta
  Vesta
  Vesta

  Westinghouse/
    Haztech
   Westinghouse/
    Haztech
   Weston
   Weston

   Weston
   Weston
   Weston
_._


. .
Chevron Refinery
S. Crop Services
__— — — ^— — — —

Indicator compound

BOAT
Pentachlorophenol
Contam-
inant
cone, in
treated
soil
(mg/k)

0.003
Trial
burn
required

Yes
Particulate
emissions
(mg/dNm3
@7% 02)

80

RCRA
permit
No
No

TSCA
.permit
••• No
No
gas station

confidential

confidential

Vertac

Nyanza
Rocky Boy
S. Crop Services
American Crossarm
Fort A. P. Hill

Peak Oil

La Salle

Revenue,
 Letterkenny Depot

 Tinker AFB
 Paxton Avenue
 Lauder Salvage
Total hydrocarbons

Total hydrocarbons

Total hydrocarbons

.Dioxins

Nitrobenzene
Pentachlorophenol
DDT
Dioxin
Dioxin

PCB's

 PCB's

 PAH's
 Benzene, toluene,
  xylene
 Trichloroethylene
 RCRA constituents
 PCB's
<0.2
<0.001
<0.001
<2

<0.33




<2
No

No

No

Yes

Yes
Yes
Yes
Yes
Yes

Yes

Yes..

 No
 No

 No
 Yes
 Yes
                                                            18
                     183

                      46

                      69
                      25
                      46

                    <183

                    <183
                       46
No

No

No

No .

No
No
No ,
No
No

No

No

No
No

 No
 No
 No
No

No

No

No

No
No
No
No
No

No

No

 No
 No

 No
. No
Yes
  compliance with the permit.  Performance data
  reported for each test run includes:
     • Carbon monoxide in the stack exhaust gas
     • Waste feed rate
     • Combustion temperature
     * Combustion gas flow rate
     • ORE results
     • Particulate emissions results
     • HCI results.
     Normal fluctuations in the parameters should also
   be reported.
      Table 2-5 lists the European Community (EC) re-
   quirements for new municipal  incinerator plants.
   Again  these are  not the only  standards or the most
   stringent standards.  Before these standards were im-
   plemented, a more stringent set of standards had been
   proposed for Germany. Table 2-6 lists typical in-
   cinerator operating conditions in the EC.
                                     The incineration system must not only meet emis-
                                  sions standards, but it must also meet other cleanup
                                  standards.  Methods to develop these standards vary
                                  between countries and within countries.  Table z-f
                                  summarizes some of these.

                                  2.6  Factors To  Consider for Determining
                                        Applicability of the Technology
                                      Waste properties affect  incineration performance.
                                  Treatability testing using the specific waste from the
                                  contaminated site will allow investigation and  iden-
                                  tification of these potential problem areas and will pro-
                                  vide data on the applicability of the actual waste
                                  stream for a specific technology.  Prior to treatabilrty
                                  testing, complete  laboratory analysis for the fo lowing
                                  key physical and chemical properties of the waste feed
                                   matrix  are recommended: density, moisture content,
                                   heating value,  noncombustible ash content, particle
                                   size analysis, flash poiint, elemental analysis/composi-
                                   tion pH, metal species and  concentrations, and or-
                                   ganic species and concentrations. Treatability testing
                                   that includes  bench or pilot scale testing will establish
                                                       17

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   Total dust

   Motels
    Pb+Cr+Cu+Mn
    Ni+As
    Cd
    Ho

   HCl

   HF
  CO

  Total organlcs (as C)
lean Community emission limits
New
>5
30
1 5
1
0.1
0.1
50
2
300
100
=) 20
for municipal incinerators.
Plant**
. lant 	 Existing Plant**
<5 >6 1-6 <,
100 100 150 600
5
1
0.1
0.1
100
4
300
100 100 100 100
20
                      at 273 ฐK> 101'3 kpa-
                                               or 9% co* dry-
!h!ซ!w9/6 ฐf reco.mmended operating parameters for
Sfhin ฑn{T!llerCial U-nit 10 assure oAmum operation
SSSi  T'ft0ry ^qu'rements.  For incineration tech-
Includes5-'   ฐrmatlon necessary for treatability testing
   ซ Chemical composition of the waste feed
   ป Heat of combustion of the waste feed
   * Viscosity
   * Corrosivity
   ปIgnitability
   ซ Reactivity
   • Polymerization
   ซ Solfds content of waste feed
    • Metal content of waste feed.
    Once treatability tests are conducted,  data
 developed from the tests will help in deciding what ad-
 ditional information is needed. This could include:
    • Feed preparation data (materials handling)
    • Baseline operating conditions (residence times
     and temperature  in the primary and secondary
     chamber)                                    '
   * Energy consumption estimates
   • Ash storage and post treatment requirements.
   These  treatability tests  and appropriate analyses
will prov.de  data on the expected performance  of a
          Incinerator type
         ^™***^™*^*—l^       i   i—.
          Liquid injection

          Fumo

          Rotary kiln
          Afterburner hearth
          Primary chamber
          Secondary chamber

         Fluidizod bed
Combustion zone
temperature, ฐC
— • 	 	 	 . 	
980-1650
700-820
650-1260
1100-1370
650-980
760-1200
760-1100
	 	 	 	 	
Combustion gas
residence time, S
- — 	 	 	 	 _
0.3-2.0
0.3-0.5
2 hours (solids)
1.0-3.0
1.5-2.5
1 .0-5.0
Excess air, %
stoichiometric
120-250
50-200
50-250
1 20-200
30-200
200-400
100-15O
                                                18

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                                                                                   Thermal Technologies
Table 2-7. Methods to develop cleanup standards by country.
  Canada
    Only Quebec has a formalized approach.  A comprehen-
    sive list of generic criteria adapted from the "Dutch List"
    (see The Netherlands) is used for initial guidance and
    screening, with site-specific risk assessments as appropri-
    ate. ,
  Denmark
    No national approach; control by  local governments.  Use
    "Dutch List" for general guidance and screening as well
    as existing Danish standards where available. Final deci-
    sion on a  particular site based on site-specific consider-
    ations.  Formalized risk assessment methods now under
    development.
  France
    No national approach; control by  local governments.  Use
    qualitative risk assessments.  If pollution  is by natural
    substance, must reference background levels. Develop-
    ment of standards for soil pollution now under consider-
    ation.
  Germany
    No national approach; control by  provincial governments.
    Use of "Dutch List" with consideration given to  local
    conditions. German "Guides/Threshold" values for soil
    contamination now under development based on soil pro-
    tection policy initiated in 1985.
  The Netherlands
    National policy for maintaining soil "multi-function-
    ality."  Generic criteria (A-B-C levels) for evaluating
    significance of pollution enacted in 1983 (often re-
    ferred to as the "Dutch List"). Reference values
    for good  soil quality (new A-level) enacted in
    1987.  Contaminated land must be cleaned to
    multi-functional  quality (A-level)  unless it is techni-
    cally or financially unfeasible or environmentally
    harmful to do so.
  United Kingdom
    No national system. National guidance on "Trigger
    Concentrations" for some contaminants commonly
    found on industrial  sites often considered for rede-
    velopment.
  United States
    For NPL (National Priorities List)  sites (i.e. Super-
    fund), use federal and state requirements where
    available  and formal site-specific risk assessment
    methodologies.  For non-NPL sites, procedures
    vary widely by state and government jurisdiction,
    and include either generic criteria background
    levels,  or levels determined by site-specific formal
    risk assessment methodologies.
commercial scale unit. This information will be used to
determine compliance with regulations on incineration
technologies.  Before any treatability testing starts,
performance criteria for the technology and  limits on
the various emission streams needs to be determined.
For thermal technologies, the following need to be con-
sidered for regulatory compliance monitoring:
   • Physical and chemical characteristics of the feed

   • ORE levels for designated compounds and the
     presence of  PIC's (products of incomplete com-
     bustion) in the stack gas

   • Levels of HCI and particulates in the stack gas
   • Oa, CO, COa, NOx and SOx concentrations in the
     stack gas

   • Levels of various compounds (metals, dioxins) in
     the ash

   • Levels of  various compounds  (dioxins, PCB's,
     etc.) and other parameters (pH, TOC, etc.) in the
     scrubber water.

   Following waste  feed analysis and treatability test-
ing, an assessment for compliance with governmental
regulations for  incineration must be conducted.
   Based on the evaluation of technology performance
parameters, information on both physical and chemical
characteristics of the waste matrix  is necessary to
determine the suitability of that particular waste for
thermal processing and the  possible need for waste
preparation and pretreatment.  Table 2-8  presents  a
range of waste characteristics that are suitable for the
electric infrared incineration system.  An applicable
range of waste characteristics needs to be prepared
for each technology under consideration.
   Site requirements for the operation  of the various
fixed or transportable incineration technologies are dif-
ferent, based  primarily on the throughput of the tech-
nology.  A thorough description of the technology
including major components  and on-site needs  is re-
quired.  At a fixed facility, many of these needs can be
addressed in  the  design  and location  of the facility.
However, the  requirements for a transportable system
can determine or affect the selection  of a technology.
When considering the use of any incineration system,
the following characteristics are important  considera-
tions:
   • Climate
   • Geology
   • Topography.

Other requirements include:
                                                    19

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 Chapter 2
Table 2-8.  Waste characteristics suitable for electric in-
           frared incineration.
  Characteristics
                        Applicable Range
  Morphology
  Particle size
  Moisture content

  Density
  Hosting value
  Orgonics (including
   POHC's)
  Chlorine
  Sulfur
  Phosphorous
  PH
  Alkali metals
  Heavy metals
Solid (soil)
Semi-solid
Oily sludge (solid phase)
5 microns (2 inch) diameter
0-50 %wt (no free liquids or
 free-flowing sludges)
480 - 2082 kg/m3
0 - 23,244 Joules/g
0-100 %wt (determined by
 pre-operation testing)
0 - 5 %wt
0-5 %wt
0 - 300 ppm
5-9
0 - 1  %wt
0-1  %wt (determined by pre-
 operation testing)
   • Utilities including water, electrical, fuel, and
     telephone.  Water will be required for the process,
     equipment  and personnel decontamination, and
     drinking purposes. Electricity will be required for
     the process, offices,  laboratories, and monitoring
     equipment. Telephone service is essential, espe-
     cially for emergency response.

   ป Support Facilities including office and laboratory
     space, pad for setting up the  system,  pad for
     decontamination, sanitary facilities, parking area,
     and a visitors area must be defined.

   "Support Equipment may  include monitoring
     wells, excavation equipment, waste feed storage,
     decontamination equipment, sampling equipment,
     scales, forklift, analytical  equipment,  and health
     and safety equipment.

   ซ Services and Supply.  A security service may be
     needed to patrol the  site when personnel are not
     on the site.  Office supplies and sampling supplies
     will be needed.
   • Site Preparation, Equipment Setup, and Feed
     Preparation.  Site development needs and im-
     provements must be complete  before arrival of
     the unit and any field activities begin.

   In addition to the site requirements, other prepara-
tions relating to the operation of the  technology need
to be considered.  These are referred to  as material
handling requirements.  They can include waste ex-
cavation, feed preparation, and ash handling systems.

2.7   Costs
   Incineration costs will vary significantly  from site to
site.  Unfortunately, costs are sources of controversy
during site remediation.  The relatively high costs of
incineration often eliminate it as a treatment option.
This being the case, it is very important to  conduct an
accurate  cost assessment.   The following provides
some preliminary background information on this topic.
   The total cost of an incineration system varies with
several factors, including:
   • System capacity
   • Types of feedstocks
   • Regime (i.e., slagging vs ashing)
   • Length to diameter (L/D) ratio for rotary kilns
   • Type of solids discharge system
   • Type and capacity of afterburner
 .  • Type of auxiliary fuel used
   • Regulations.

   The cost of waste treatment also  varies consider-
ably from site to site; any estimate should  include the
following:
   • Site preparation
   • Permitting and regulatory requirements
   • Capital equipment
   • Start-up
   • Labor
   • Consumables and supplies
   • Utilities
Table 2-9. Typical costs of incineration of contaminated soils (in US$, 1988).
                                               Capacity (tonnes/h)
                                                      Unit cost ($/tonne)
  Centralized rotary kiln system

  Onsite incineration
   Smell site (<4,500 tonnes)
   Medium site (4,500 to 18,000 tonnes)
   Largo site (> 18,000 tonnes)
                         Commercial unit
                             <4.5
                           4.5 to 9.0
                             >9.0
                         330 to 720



                        1100 to 1360
                         330 to 880
                         110 to 440
 •Not Including the cost of transportation, removal of soils from the ground, or storage.
                                                    20

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                                                                              Thermal Technologies
   • Effluent treatment and disposal
   • Residuals/waste shipping and handling
   • Analytical services
   • Maintenance and modifications
   • Demobilization.

   Table 2-9 presents the estimated costs of incinerat-
ing contaminated soils in both on-site and off-site in-
cineration systems.  These  costs  do not include
transportation, storage, or removal of the soil from the
ground.
   Thermal treatment vendors generally prefer to bid
on projects where a processed waste is ready to feed
into their unit. Quotes are also based on the assump-
tions that the residue from the unit will meet discharge
standards  and that the thermal unit can operate  at
capacity for the length of the job. Failure to adequately
plan the technical requirements and estimate the costs
of a site remediation project can result in cost overruns
and possibly an incomplete remediation.
   In  addition to capital cost data, operational and
maintenance  (O&M) cost  data from previous studies
(pilot- or field-scale) need to be collected. O&M costs
include labor, power,  fuel,  chemicals, and main-
tenance needed to operate the system. The O&M cost
will also include costs for health and safety considera-
tions,  and regulatory requirements, such as permitting.
   Because of the various types of thermal treatment
technologies, prices will vary  widely.  The range  in
price  between low temperature (thermal desorption
technology) and high temperature incineration varies
widely.  Reported ranges for thermal technologies are
between US$60 and US$1,300 per tonne.  To  ade-
quately assess the costs 'for an individual project, the
above cost categories must be rigorously examined.

2.8   Future Status of Case Study
      Processes and Thermal
      Technologies as a Whole
   Incineration has  been a selected option for site
remediation and for the destruction of organics for
many years. Several incineration manufacturers  have
been in business for many years. Changes in the ther-
mal technologies have been introduced as a result of
changing environmental regulations.  With the applica-
tion of thermal technologies to site remediation, these
technologies now  must deal with a wide spectrum of
organic and in some cases inorganic contamination in
the waste matrix.  With increasing  environmental
monitoring and further understanding of thermal
destruction processes, manufacturers and operators of
thermal technologies have kept pace in the design and
operation of these units. Concerns over the transpor-
tation of waste off-site during site remediation has led
to the development of mobile  (transportable) units.
Each of the types of units discussed in this chapter has
undergone modification either by the original users or
by others using the same technology.  These modifica-
tions have addressed meeting or exceeding environ-
mental standards and controlling the costs of  operating
thermal technologies.
REFERENCES
     Cudahy, J.J. and Troxler, W.L. Thermal remediation industry contractor survey. 1m Journal of Air and
     Waste Management Association, 40(8), August 1990.

     Evans, G.M. Estimating innovative technology costs for the SITE program. 1m Journal of Air and Waste
     Management Association, 40(7):1047-1051, July 1990.

     Freeman, H.M. Standard handbook of hazardous waste treatment and disposal, McGraw-Hill, 1988, Chap-
     ters 2, 8.

     Handbook:  Permit writer's guide to test burn data, hazardous waste incineration. EPA/625/6-86/012, U.S.
     Environmental Protection Agency, Cincinnati, Ohio, September 1986.

     House of Lords Select Committee on the European Communities.  Air pollution from municipal waste in-
     cineration plants.  HMSO, Great Britain, 1989.

     James, S.C. Guidance for the field demonstration of remediation technologies. Jo: Journal of Air and
     Waste Management Association, 40(5), May 1990.

     NATO/CCMS Fourth International Conference.  Demonstration of remedial action technologies for con-
     taminated land and ground water. Angers, France, 5-9 November 1990.

     NATO/CCMS Pilot Study. Demonstration of remedial action technologies for contaminated land and ground
     water. Fourth International Workshop, Oslo, Norway, 13-15 March 1990.

     Shirco Infrared Incineration System: Applications analysis report. EPA/540/A5-89/010, U.S. Environmental
     Protection Agency, Cincinnati, Ohio, June 1989.
                                                 21

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Chapter 2
     Soczo, E.R. and Versluijs, C.W.  Review of soil treatment techniques in The Netherlands. National Institute
     of Public Health and Environmental Protection, Laboratory for Waste Materials and Emissions, Bil-
     thoven, The Netherlands.

     Superfund Engineering Issue: Issues affecting the applicability and success of remedial/removal incinera-
     tion projects. EPA/540/2-91/004, U.S. Environmental Protection Agency, Cincinnati, Ohio, February
     1991.

     Technology Evaluation Report: SITE program demonstration test: Shirco infrared incineration system, Peak
     Oil, Brandon, Florida.  EPA/540/5-88/002a, U.S. Environmental Protection Agency, Cincinnati, Ohio,
     September 1988.

     Technology Evaluation Report: SITE program demonstration test: Shirco pilot-scale infrared incineration
     system at the Rose Township Demode Road Superfund site.  EPA/540/5-89/007a, U.S. Environmental
     Protection Agency, Cincinnati, Ohio, April 1989.
                                                 22

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Stabilization/Solidification Technologies

Merten Hinsenveld
University of Cincinnati, Department of Civil and Environmental Engineering
741 Baldwin Hall (ML 71), Cincinnati, Ohio 45221-0071
United States
ABSTRACT

   Cement-based stabilization/solidification (S/S) tephniques attempt to prevent migration of contaminants into the
environment by forming a solid mass. The techniques chosen in the Pilot Study were: (1) Hazcon (United States),
applying ex situ treatment with Portland cement; (2) EIF Ecology (France), applying surface treatment with lime; and
(3) TREDI (France), using the Petrifix process. Only one of them (Hazcon, presently IM-Tech) yielded enough
information for evaluation.
   The case study processes accepted in the NATO/CCMS Pilot Study all apply generic binders, such as cement,
pozzolanic material, or lime.  No case studies applying other binders were submitted. In all cases, the combination
of metals mixed with organic components and a large site to be treated were the major incentives for applying S/S
treatment.
   S/S may lead to a substantial increase in the total volume of waste (more than 100 percent). Consequently, it is
possible that the treated material cannot be accommodated at the original site. Heavy metals in these processes are
retained in the stabilized product by physical entrapment and precipitation.
   In the Hazcon case, extensive leaching data exist on the treated soil. However, only limited leaching data are
available, on the original untreated wastes. This makes an evaluationpf the process difficult. From the available data
it can be concluded that the process leads to a strong reduction of the leachate concentrations. A reduction factor of
100 for lead, the predominant metal at the site, was seen during a demonstration on site, using the TCLP test. Similar
results were observed for zinc. For organic contaminants the process is generally not effective.
   The Hazcon case  provided extensive cost data from which an indication of the gieneral cost factors may be
obtained.
3.1   Introduction

3.1.1  Place of the Techniques in a Broad Sense
   Stabilization/solidification (S/S) refers to techniques
that  attempt to prevent migration of contaminated
material into the environment by forming a solid mass.
The two terms are generally used together.  Stabiliza-
tion  refers to  rendering the material insoluble;
solidification refers to the process of converting a liquid.
or sludge-like  waste into a solid form by  adding  a
binder. Even for materials already in solid form, like
soil, the process is referred to as, "S/S" treatment. In
practice the terms stabilization and immobilization are
often used as shorthand for stabilization/solidification.
Solidification solely to improve handling characteristics
will not be considered in this chapter.
   Many S/S technologies have been proposed and
tried in the  past ten years. Some  of them are
proprietary, involving the addition of adsorbents and
solidifying agents. The  S/S binders can be divided into
two major groups:
   • Inorganic binders,  such as cement, lime, kiln dust,
    fly ash, silicates, clay, and zeolites

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Chapters
   • Organic binders, such as asphalt, polyethylene,
     resins, epoxies, urea formaldehyde, polyesters,
     and organophilic clays.

   This chapter deals with stabilization processes
using generic binders, such as Portland cement, lime,
and fly ash.
   The advantage of organic binders often is their
ability to stabilize highly soluble wastes and to chemi-
cally bind organic contaminants.  This is not possible
with cement  and pozzolanic materials. Organic
binders, however,  are more expensive than cement
and pozzolans, and may be undesirable from an en-
vironmental point of view. Their application, therefore,
has been limited to specific wastes, such as nuclear
waste and highly toxic industrial waste.
   Besides the use  of binders for immobilization of
contaminants, thermal methods (vitrification)  may be
used. Vitrification is  a promising technique,  since it
combines destruction of organic contaminants with the
incorporation of metals in the  resulting  glass-like
matrix. See Chapter 2 for a general description of this
technology. The high cost involved in treatment and
the difficulty of permitting, however, are likely to
hamper the application of vitrification on a large scale.
   S/S may be used in a variety of applications. In situ
treatment is used when excavation is undesirable for
health reasons (e.g., dust emissions) or simply to
avoid the cost of excavation. It refers to mixing the soil
in situ with a  hollow auger mixer through which the
water-binder mix is pumped into the soil. This techni-
que will not be described in this chapter.
   Another application is S/S surface treatment, in
which only the top layer of contaminated soil is treated.
This application attempts to reduce the amount of
water penetrating the waste, and does not stabilize the
complete waste. Surface treatment reduces leaching
of contaminants from the untreated waste underneath,
but has too limited neutralization capacity for long-term
durability. Surface treatment will be briefly discussed in
one of the case studies. S/S treatment is mainly  used
in the United States, Canada, and France. In countries
where waste is evaluated on the basis of concentration
limits rather than on leaching behavior, S/S technology
may be used, for those wastes which  cannot be
treated otherwise, to produce a material that can be
more easily landfilled.

3.1.2  The Stabilization/Solidification Process
   Conceptually,  S/S treatment with cement,  poz-
zolanic material, or combinations of them is simple. It
consists of mixing  the contaminated  material with a
binder after or during the addition of (often proprietary)
chemicals. This is followed by the setting and harden-
ing of the mix. The  added chemicals may alter the
solubility or redox potential of the waste to be stabi-
lized  or may  prevent retardation of the  hydration
process. This, in turn, may improve the binding of the
contaminants to the matrix. The essential elements in
the process are: (1) pretreatment, (2) mixing, and (3)
casting and curing.
   1. Pretreatment.  In  ex situ applications, the
material is  sieved down to a certain particle size that
can be accommodated in the process equipment. If the
waste characterization indicates that the contaminants
are concentrated in a particular particle fraction of the
waste, pretreatment should also  seriously be con-
sidered to reduce the amount of waste to be treated. If
the waste contains a large amount of water, dewater-
ing may be necessary to remove  excess  water that
cannot be accommodated in the final solidified waste
form. Contaminants present in the  excess water may
be precipitated and stabilized as well. Homogenizing
the waste improves the consistency of the stabilized
product and the  performance of the process.  Before
mixing the  waste with the binders, chemicals can be
added to convert the contaminants  to a non toxic or a
less soluble form.
   2. Mixing. Mixing waste and binders can be done
ex situ or in situ. Ex situ mixing is more controllable
and attempts to produce a stable waste form by pump-
ing the mix into a mold. Mixing is the most critical step
in the  process.  Although it is conceptually simple,
many vendors have difficulty in executing this step for
two reasons:
   • Insufficient homogeneity of the original waste

   • Insufficient capability to adequately disperse the
    waste  in the binder mix.

   Insufficient mixing leaves waste forms that have  a
large variability in performance and may contain large
clumps of pure waste. This lowers the integrity of the
final waste form.
   3. Casting and curing. The waste-binder mix is
pumped into  a mold or a lagoon.  When cast  into  a
small mold, the mix should preferably set rapidly, so
that the mold is  available for a new cast quickly. In
case of a lagoon hardening, timing  is less critical, but
still important since the mix is introduced in the  lagoon
in layers that should set before the  next layer is intro-
duced.
   If the stabilized material is deposited on  a noncon-
trolled landfill the integrity of the material, as well as
the leachate concentrations, should be monitored.   It
may be necessary to treat the waste a second time  if
the release increases to unacceptable proportions.
   Although many experts believe that the  major part
of the contaminants will ultimately be released, the
concentrations in the leachate at any one time can be
low enough to pose no direct hazard to the environ-
ment. However, if the waste leaches for  an extended
period  of time, the environment will become  largely
loaded with contaminants unless the contaminants are
                                                  24

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                                                             Stabilization/Solidification Technologies
remineralized and components are  incorporated into
soil organic matter.

3.2  Case Studies Chosen
   Knowledge about S/S treatment processes is rapid-
ly increasing.  The case studies discussed in this chap-
ter  do not  represent the most recent status of the
technology. Furthermore, the technologies presented
do not, by far, represent the full range of S/S technol-
ogy now available. The technologies  chosen for the
NATO/CCMS Pilot Study only serve as a general il-
lustration of the available technology.
   Three case studies in which three different vendors
applied  their technology where  chosen for the
NATO/CCMS Pilot Study. These are:
   • EIF Ecology (France), applying surface treatment
    with lime
   • TREDI (France), using the Petrifix process
   • Hazcon (United States),  applying ex situ treat-
    ment with Portland cement.

   The problems handled  by  the manufacturers are
summarized in Table 3-1. The rationale  behind the
choice of these technologies is indicated below.

3.2.1  Case Study 3-A: In Situ Lime Stabilization
      (EIF Ecology), France
   In  this study, described in Appendix 3-A, on-site
stabilization at two sites in France was evaluated
(Sites A and B in Appendix 3-A). The immobilization
process consisted of mixing the material with lime. The
sites are  contaminated with a variety of hydrocarbons
and heavy metals. The study was chosen because the
NATO/CCMS members felt it useful to evaluate the
practice of S/S treatment in  France.  Since the
remediation was  already completed at the start of the
NATO/CCMS Pilot Study, these sites provided limited
information.

3.2.2  Case Study 3-B: Petrifix Process (TREDI),
      France
   The Petrifix process  was used by TREDI to stabi-
lize contaminants at two sites in France. These sites
are also described in Appendix 3-A as Sites C and  D.
Site C is a former  industrial disposal  site, con-
taminated  with  a variety  of  contaminants, mainly
chromium, sulfates, and  sulfides. The  study  was
chosen for the same reasons as the EIF process.

3.2.3  Case Study 3-C: Portland Cement (Hazcon,
      presently IM-Tech), United States
   The  Hazcon process (presently IM-Tech)  is a
proprietary  process using a patented nontoxic chemi-
cal called Chloranan (U.S. EPA 1989). Chloranan is
claimed to neutralize the inhibiting effects that organic
contaminants normally  have on the hydration of ce-
ment-based materials. The process is described in Ap-
pendix 3-B and was chosen for three reasons. First,
because the  study resulted in a detailed evaluation of
the process, and can be regarded indicative of the
results to be obtained with other cement stabilization
techniques. Second, because the technique was ap-
plied on a waste containing large amounts of organic
components. Third, because the process  is available
on a commercial scale making an economic evaluation
possible.  (For more information on this project, see
Appendix 3-B.)

3.3   Background of Case Study Sites as a
      Group
   The cases accepted in the NATO/CCMS Pilot
Study all apply cement, pozzolanic  material, or lime.
These binders are the most generic ones used to date.
No case studies applying other binders were  sub-
mitted. In all case studies,  the combination of metals
mixed with organic components plus a large site to  be
treated was the major incentive in applying S/S treat-
ment.

3.4   Performance Results
   Leachability  of the contaminants after S/S treat-
ment is largely reduced due to the insoluble state of
the contaminants, physical encapsulation in the waste
form, and chemical binding to the matrix.  The perfor-
mance of S/S treatment is primarily measured  by
standard leaching  tests,  a.s  required by  regulatory
authorities. At present, only short-term tests are avail-
able. Ongoing international research in predicting the
release rate  as  a function of environmental variables
(such as soil pH, chemical composition of the contact-
ing ground water, waste characteristics,  and binder
characteristics)  should lead to  more adequate tests.
Major improvements in this area can  be expected in
the years to come.
   A wide variety  of leaching tests  is  available  at
present. Most are required by regulatory agencies, but
have a poor scientific background.  Test  results are,
therefore, difficult to compare and it  is usually unclear
what they measure, since  leaching  mechanisms are
still poorly understood. Examples of leaching tests are:
   • Toxicity Characteristic Leaching Procedure,  or
    TCLP (United States)

   • Multiple Extraction Procedure, or MEP (United
    States)

   • American  Nuclear Society test method  16.1,  or
    ANSI 6.1 (United States)

   • Waste Extraction Test, or WET (United States)

   • SOSUF test (The Netherlands)
                                                 25

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Chapters
Table 3-1.  Problem handled in these NATO/CCMS case studies.
Process/technique
Manufacturer
Country
City
Area |mj)
Depth (m)
Amount of soil to be
Lime stabilization
EIF-Ecology
France
Site A: Marais de Ponteau-Lavera
Site B: Bourron Marlotte
Site B: 4,200
Site B: 6-7
Site A: 22,000 m3
Petrifix
TREDI
France
Site C: Nesle-Somme
Site D: Bellay-Ain

Site C: 5
Site D: 2.5
Site C: 6,804 tonnes
Portland cement
Hazcon (presently IM-Tech)
United States
Douglassville, PA
Total of five areas in the
site: 200,000
Unknown
200,000 m3
 treated

 Source
 Type of soil
 Typo and
 concentrations of
 contaminants
 Main lesson learned
 Site B: 22,680 tonnes

 Site A: Industrial residues of the
  Lavera petrochemical plant (sludges
  and sediments)
 Site B: Industrial residues from an old
  refinery plant (mainly acid tars and
  filtration residues)

 Site A: Not known
 Site B: Top layer - light and viscous
  material; middle layer - aqueous
  liquid; bottom layer - sticky material
  (composition unknown)
Site D: 8,165 tonnes

Site C: Industrial residues
Site D: Sludges from tannery
 plant wastewater treatment
Site C: Black-colored sludges
 and silty material
Site D: Not known
Site A: Not known                      Site C: Concentrations in
Site B: Not known                       leachate: COD up to 450
                                        mg/l; iron up to 47 mg/l;
                                        ammonia up to 80 mg/l;
                                        traces of copper and zinc
                                        (concentrations in the
                                        material itself unknown)
                                       Site D: Chromium 8,700
                                        mg/kg; sulfide 475 mg/kg;
                                        sulfates 500 mg/kg;
                                        nitrogen 350,000 mg/kg
                                        (35%)

Absence of data concerning the original waste characteristics and
concentrations makes evaluation and technology transfer impossible.
                                                                                               Oil recycling facility, with
                                                                                               wastewater sludge,
                                                                                               recycling oil, and filtercake
Five different wastes:
Site A: Oily sludge from
 wastewater treatment
Site B: Oily filtercake
Site C: Oil and oily water
Site D: Sludge (landfarming
 area)
Site E: Plant processing
 area

Lead 3,000 - 22,000
mg/kg (0.3-2.2%); oil and
grease 10,000 - 250,000
mg/kg (1-25%); VOC's 0-
150 mg/kg; semivolatile
organics 12-530 mg/kg;
PCB's 1.2-54 mg/kg; pH
2.6-7.0
                                                                                               Leachate characteristics of
                                                                                               treated material along are
                                                                                               not sufficient for a good
                                                                                               evaluation; leachate quality
                                                                                               from both treated and
                                                                                               untreated waste was
                                                                                               identical. The raw material
                                                                                               feed system  and the
                                                                                               blender may  be critical in
                                                                                               the process.
                                                           26

-------
                                                              Stabilization/Solidification Technologies
   •AfNOR  Standard Test X31 210 (France).  This
    test, to be used in France, strongly resembles the
    United States TCLP.

   Since leaching tests only  provide limited informa-
tion concerning long-term performance, several other
tests,  relating to the integrity  of the waste form under
various environmental conditions may be carried out,
such as:
   • Homogeneity of the final  product, which is also an
    indicator of the performance of the mixing opera-
    tion

   • Physical performance, such as strength

   • Influence of weather conditions, such as freeze-
    thaw and wet-dry performance

   • Acid neutralization capacity, which relates to the
    ability of the stabilized product to neutralize acids.

   Although the formation of a monolith is desirable to
guarantee the encapsulation  of the contaminants, it is
recognized that the performance of nonmonolithic or
"soil-like" waste forms may be as good or better than
monolithic waste forms (Barth and McCandless 1989).
   EIF Ecology. The information provided by this ven-
dor was too limited to be able to evaluate the perfor-
mance.
   TREDI. As in the  EIF Ecology stabilization, little is
known about the performance of the TREDI stabiliza-
tion.
   Hazcon.  The primary goal of the evaluation of the
Hazcon process was  to compare contaminant mobility
of the untreated versus treated soil. Although  exten-
sive leachate data exist on the treated soil, only limited
data are available on the original untreated wastes.
This makes  a comparison difficult. From the available
data it can be concluded that the process leads to a
strong reduction of  the  leachate concentration. A
reduction factor of 100 for lead, the predominant metal
at the site, was  seen during  the SITE demonstration
using the TCLP. Similar results were observed for zinc.
For organic contaminants, the process is generally not
effective. In most cases the  extracts from  the TCLP
leaching tests of untreated soil were found to be identi-
cal to those of the treated soil. Some data available on
the treatment of petroleum refinery wastes, however,
showed sharp reductions in leachate concentration
after waste treatment (U.S. EPA 1989). This indicates
that there might be selected applications where immo-
bilization of organics occurs. During the project,
numerous operating  difficulties were encountered by
Hazcon. Main shortcomings  were encountered in the
raw material feed system and in the blender.  It is
believed that improvements in this field can largely im-
prove operations.
3.5   Residuals and Emissions
   Stabilization/solidification leads to a strong in-
crease in the total, volume of waste. Since increases of
more than 100 percent are normal, the treated material
often cannot be accommodated in the original site and
must be  landfilled elsewhere. If the  treated waste is
very wet, a part of the process water must be cleaned.
The resulting sludge, however,  may be recycled back
into the system.
   The S/S process produces heat, which can lead to
emission of  hazardous components. Most of the
VOC's were volatilized during the Hazcon operation. In
cases where a large amount of VOC's is present, the
process should be executed in a closed system, where
the VOC's can be trapped and subsequently treated.
   An  inherent feature of isolidified waste is its leach-
ing ability. If improperly landfilled, most of the con-
taminants may eventually leach out. If the stabilized
waste is properly landfilled, (i.e., the landfill is properly
lined to prevent contact with ground and rain water)
leaching  into  the environment is not a problem. Ade-
quate  maintenance of a landfill in this  respect is of
major importance.

3.6   Factors to Consider for Determining
      the Applicability of the Technology

3.6.1  Limitations and Restrictions on the Use of
      the Technology
   S/S technology can be considered for two major
reasons.  The first is that no other treatment methods
are available for the particular site. This is specifically
true for wastes containing heavy  metals mixed with
small  amounts of organic contaminants. The second
reason is that the technique is more cost effective than
other techniques.
   Generally the cement- or lime-based binders have
not been proven successful in stabilizing organic com-
ponents. Although it may be possible to treat material
containing organic components  by adding certain
chemicals to prevent the unwanted effect  of the or-
ganic contaminants on  the cement hydration, the or-
ganic contaminants themselves are not well retained in
the stabilized waste form. Cement-based stabilization
techniques are, therefore, only applicable to wastes in
which  metals are the main source of  contamination
and where the release of organic contaminants is not
considered a main problem. The technique should not
be applied when the organics are highly toxic or where
large  amounts of volatile organic contaminants are
present.
   A  drawback of  S/S technologies  is their ques-
tionable long-term durability.  Analyses of crushed
samples show that there often  is hardly any chemical
binding, which implies that most of the contaminants in
the solidified waste form are essentially mobile and will
                                                  27

-------
  Chapter 3
  eventually leach out of the stabilized material. Physical
  entrapment and adsorption, however, strongly reduce
  the velocity of release.
     Another drawback of S/S  technology is that it re-
  quires large amounts of chemicals and leads to sub-
  stantial  volume  increases of  the stabilized products.
  Especially for dry materials like soil, an  increase of
  more  than 100 percent can be expected. Volume in-
  creases up to 140 percent have been reported. This
  means that the disposal site  needs to be more than
  double the size of the original site. In designing dump
  sites this factor will have to be taken into account.
     A summary of the  limitations related to the case-
  study projects is given in Table 3-2.
                                concentrations. The metals, however, are essentially
                                mobile. The stabilized material  should, therefore,  be
                                deposited on a controlled dump  site with adequate
                                drainage  and treatment facilities to prevent migration
                                into the environment.
                                3.6.2 Steps in Determining the Applicability of S/S
                                      Treatment
                                   A general five-phase investigation, to assess the
                                possible application of immobilization, is given by
                                Barth and McCandless (Barth and McCandless 1989)
                                and consists of:
 Table 3-2.  Limitations of the case study techniques.
   Manufacturer
   Technique
                            EIF-EcoIogy
 Lime Stabilization
                                                               TREDI
                                                               Petrifix
                           Hazcon (presently IM-
                           Tech)

                           Cement plus additives
   InJEx situ

   Feature of process used




   Long-term effect


   Release mechanism
 In situ

 Heavy metals are partly encapsulated;
 buffering capacity is the main cause of
 delayed release.

 If the waste is not stored dry,
 contaminants will be released

 Release is partly governed by diffusion.
 The waste form easily disintegrates,
 enlarging surface area. Utilization of
 acid neutralization capacity is the major
 release factor.
In situ
                           Ex situ
Heavy metals are encapsulated and precipitated; some
chemical binding may occur.
If the treated waste is not stored dry, contaminants will
be released.

Release is partly governed by diffusion and accelerated
when the waste form breaks up, due to increase of
surface area.  Utilization of acid neutralization capacity
is thought to be a major release factor.
  Typo of soil; fraction of       No limitations
   fines, organic* and rubble
  Type of contaminants

  Concentration of
   contaminants

  Volume increase
                                    No limitations
                                                               No limitations
                Organics are not immobilized; volatile organics may be released.

 No limitations                        No limitations                No limitations



	Depends largely on water content; dry solids will lead to an increase of 100-140%.
    In the EIF Ecology process, the contaminants are
essentially trapped due to the low solubility in the high
pH environment of the mix. Release, therefore,  strong-
ly depends on the acid neutralization capacity of the
stabilized product. In general, lime  as a sole binder is
not very effective.
   In the  Hazcon process, heavy metals are retained
in the stabilized product mostly by physical entrapment
and precipitation. The buffering capacity of the stabi-
lized material leads to a strong reduction in leachate
                                  1. Site sampling
                                  2. Waste acceptance/project planning
                                  3. Waste characterization
                                  4. Binder screening
                                  5. Performance testing.

                                  1. Site sampling. Many techniques are available
                              for taking a representative sample. In most cases, site
                              sampling for bench testing can be aimed at obtaining
                              either  a "worst case" sample and/or an "overall
                                                     28

-------
                                                               Stabilization/Solidification Tecfinofogfes
average" sample. The choice depends on the nature of
the waste and the quality and amount of data available
to the planner. For the treatability study, a sample of at
least 130 kg is recommended (Earth and McCandless
1989). An assessment of variability of the waste is im-
portant for determining the  size and number of
samples to be taken.
   2.  Waste acceptance. Generally, laboratory per-
mits are restricted to certain components and wastes.
An analysis of a representative  sample should give in-
formation on the  type of laboratory  needed for the
treatability study. Furthermore,  the waste acceptance
investigation should provide information about pos-
sible health  aspects that have  to be accounted for in
the study.
   3. Waste characterization.  Prior to binder screen-
ing and  performance testing,  the  waste is charac-
terized to obtain information needed to plan S/S
treatment. Important objectives of the waste charac-
terization are to:
   ป Assess the possibility of applying additional tech-
    niques in order to reduce the amount of waste to
    be treated.  In case the contaminants are con-
    centrated in a fraction of specific particle size, a
    separation technique might be considered.

   • Obtain  information concerning components that
    are known inhibitors to the hydration and setting
    of cement and pozzolans.

   Leaching behavior of the original waste is important
because  it gives information on the potential effective-
ness of the S/S treatment. In some cases it has been
established that leaching rates  after stabilization were
higher than before treatment, making the application of
S/S somewhat dubious. Establishing the original con-
centration of the total and soluble fraction of the con-
taminants to be immobilized is important in terms of
interpretation of leachability studies.
   4. Binder screening. Since S/S represents a rela-
tively new alternative in remediation, little technical in-
formation,  empirical  or otherwise,  is available to
assess its  potential (Barth and  McCandless 1989).
Many factors influence the performance of the waste-
binder mix. Some important factors are: soil type, con-
taminant type, and contacting  liquid (rain water, acid
leachate, sulphate-containing ground water, etc.).
   A first step in the possible consideration of immobi-
lization is mix design. The basis of a mix design is the
assessment of binder characteristics and waste char-
acteristics,  separately and in combination,  leading to
an estimate of appropriate mix compositions. Center
Hill Research Laboratories (University of  Cincinnati
1990) establishes so-called design windows (possible
compositions), derived from pH-solubility curves and
acid neutralization capacity-pH curves. Although the
establishment of design windows yields information on
waste-binder mixes, treatability studies are a neces-
sary second step in the assessment of immobilization
as an  environmentally sound remedial alternative.
Since only limited theoretical information is available
on selection of binders for a specific waste, trial and
error approaches are followed. In general, three binder
mixes  are considered: Portland cement, cement-kiln
dust mixtures, and lime fly ash mixtures. Apart from
possible  ad-hoc combinations, a standard trial com-
bination  of binder-to-waste mixes may be applied.
Barth and McCandless (Batth and McCandless 1989)
propose trying the nine possible combinations of the
three most widely used binders (Portland cement type
I, cement kiln dust, and lime fly ash type F) and three
binder-to-waste ratios (0.1,0.3, and 0.6).
   Other parameters, such as the water-to-cement
ratio (W/C factor)  and  slump, are assessed according
to established civil engineering practices. Based on
the results of the trial mixes, further optimization is car-
ried out.
   5. Performance testings. After the composition of
the binder mix is determined in the laboratory, the sta-
bilized  specimen must be tested on a larger scale. In
laboratory tests, performance testing aims at improv-
ing the binder mix and  determining the expected
leachate concentrations  as measured by standard
leaching tests and physical integrity tests. The
laboratory tests generally result in a fine tuning of the
binder-waste mix under optimal conditions. Since in
practice the actual stabilization is performed with field
equipment under  less ideal circumstances, pilot tests
are  necessary to obtain information on the  perfor-
mance of the  actual field stabilization. Mixing, for in-
stance, may be the critical step in the field.

3.7  Costs

3.7.1 General Cost Factors
   Currently (1991), little cost  information is publicly
available. In the  NATO/CCMS  case studies, costs of
treatment were only available for Hazcon. The costs of
this particular process  are summarized in section 3.7.2
below. However, the following general cost factors for
applying S/S treatment should be taken into account,
at a minimum.
   Costs of treatability studies. S/S, more than other
technologies, is an art rather than a science. The per-
formance of the technology is established by trial and
error, rather than by design. Consequently, treatability
studies may represent a  substantial part of the total
costs,  and the cost of these studies may be an impedi-
ment to the application of the technology.
   Barth and  McCandless (Barth and McCandless
1989)  give an indication of the costs involved in as-
sessing the potential of an S/S technique. These costs
are summarized in Table 3-3 and apply only to metal-
containing wastes. Two cases are indicated in Table
3-3: for wastes containing metals only, and for wastes
                                                  29

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  Chapter 3       		

  Table 3-3. Summary of estimated treatability costs for metals (xlOOO US$, 1989).

Site sampling *
Wosto acceptance
Waste characterization
Binder screening
Performance testing
TOTAL ESTIMATED COSTS

Labor
8.0
13.1
7.7
14.9
16.1
59.8
'Metals Only
Analysis
.-
3.9
5.2
3.8
5.8
18.7

Total
8.0
17.0
12.9
18.7
21.9
78.5
Metals
Labor
8.0
13.1
7.7
18.9
17.6
65.3
Plus Non-Volatile
Analysis
—
3.9
13.5
25.9
39.6
82.9
Organics
Total
8.0
17.0
21.2
44.8
57.2
148.2
  'Estimated average; highly project-specific.
 containing a combination of metals and nonvolatile or-
 ganlcs. It should be realized that the estimated costs
 only serve as an indication of the potential costs in-
 volved. As can be seen, the analytical costs are by far
 the most  significant factor in the total  cost of a
 treatability study when complex wastes are involved.
    Regulatory costs. The costs of permitting and en-
 vironmental monitoring of operations for any  regulatory
 authority may be substantial. Costs vary widely in each
 country. In countries following a federal system (e.g.,
 Germany and the United States), the regulations may
 vary substantially within the country as well.
    Site preparation costs. These costs include ac-
 cess to feedstocks and providing utilities needed for
 the plant to operate. They also include installation of
 equipment to support the operation such as storage
 tanks, pumps, and piping. Site preparation  costs can
 be strongly influenced by site  geology, proximity to
 residential areas, quantity and type of contaminants,
 and local costs of labor, utilities, and raw materials.
    Treatment costs. These costs are generally given
 by the vendor of the technology. In the Hazcon case,
 operations are assumed to be 7 days per week and 24
 hours per day. Any reductions in this schedule would
 add to the  remediation costs by increasing  the costs
 per tonne of treated waste. A vendor generally incor-
 porates a profit factor of about 10 percent into the es-
 timated costs.
   Costs for additional landfilling and cleaning of
 process water. The site  may not be able to accom-
 modate the largely increased volume of the waste after
treatment (more than 100 percent). Costs for additional
 landfilling of the treated material can be substantial.
   Site completion. This includes the removal of sup-
port equipment at the completion of the cleanup as
well as activities related to further use of the site and
possible long-term monitoring.
 3.7.2  Costs Of The Hazcon Treatment System
    A cost' analysis of the Hazcon system (now IM-
 Tech) has been  made by the U.S. EPA (U.S. EPA
 1989). A summary of these costs is given in Table 3-4.
 It should be noted that Table 3-4 only provides an in-
 dication of some of the costs involved in S/S treatment.

 3.8   Future Status of Case Study
       Processes and the Technology as a
       Whole
    The future status of the stabilization technology as
 a whole largely depends on the policies adopted  in a
 specific country.  Countries relying on concentration-
 based threshold values to evaluate hazardous waste
 are not likely to adopt the stabilization technology. In
 some countries, mixing a waste with another material
 is considered dilution of waste and is prohibited even if
 this dilution brings the concentration below certain
 threshold values.
    In general, it can be stated that stabilization techni-
 ques (i.e., landfilling  of stabilized  waste) should be
 avoided if treatment techniques are readily avajlabje.
 However, in many current industrial processes, as well
 as in households, large amounts of unspecific mixed
 waste are produced. To clean these wastes would re-
 quire so many conventional treatment steps, that treat-
 ment in these cases is not a realistic option. As long as
 industry continues to produce these unbeatable mixed
wastes in large amounts, landfilling  will be necessary.
Stabilization techniques to  pretreat these wastes may
be an option to consider.
   The processes  discussed in this chapter are not yet
optimized. Fundamental research is needed in a num-
ber of  areas,  such as development of adequate test
methods to assess the long-term durability of stabi-
lized waste, assessment of binding mechanisms in
                                                  30

-------
                                                                     Stabilization/Solidification Technologies
Table 3-4.  Estimated costs for the Hazcon System (in US$, 1989).
                                        Demonstration Test
                                       chemical consumption2
                                       Reduced chemical consumption2
                                 136 kg/min
                                  on-stream
                                   factor3
              1044 kg/min

               on-stream
                 factor3
                        136 kg/min
                        on-stream
                          factor3
                                90%
70%
90%
70%
90%
70%
 Startup and fixed costs
   Operator training                0.84    0.84
   Site mobilization                0.83    0.83
   Depreciation costs              0.25    0.32
   Insurance and taxes             0.25    0.32

 Labor costs
   Salaries and living expenses     50.32   64.70
   Administration                 0.25    0.32

 Raw materials  ,
   Cement                      50.00   50.00
   Chloranan                    66.67   66.67

 Utilities
   Fuel                          1.00    1.29
   Electricity                     0.03    0.03
   Water                         0.08    0.08

 Other costs
   Analytical                      5.65    6.50
   Facility modifications            0.25    O.32
   Site demobilization              0.83    0.83

   TOTAL*                     188     206
              0.84
              0.83
              0.11
              0.11
              6.56
              0.11
             50.00
             66.67
         0.84
         0.83
         0.13
         0.13
         8.44
         0.13
        50.00
        66.67
              0.23    0.29

              0.07    0.07


              2.26    2.40
              0.12    0.14
              0.83    0.83
            137
                    139
              0.84
              0.83
              0.25
              0.25
             50.32
              0.25
             33.33
             44.44
                      1.00
                      0.03
                      0.08


                      5.65
                      0.25
                      0.83

                    149
          0.84
          0.83
          0.32
          0.32
         64.70
          0.32
         33.33
         44.44
                        1.29
                       0.03
                       0.08


                        6.50
                       0.32
                       0.83

                     167
1044 kg/min

  on-stream
   factor3

90%    70%
Equipment
Support
Equipment rentals
Contingency

2.25
8.05
0.25

2.25
10.36
0.32

6.75
1.05
0.11

6.75
1.35
0.13

2.25
8.05
0.25

2.25
10.36
0.32

6.75
1.05
0.11

6.75
1.35
0.13
               0.84
               0.83
               0.11
               0.11
               6.56
               0.11
             33.33
             44.44
        0.84
        0.83
        0.13
        0.13
        8.44
        0.13
       33.33
       44.44
                        0.23    0.29

                        0.07    0.07


                        2.26    2.40
                        0.12    0.14
                        0.83    0.83
                                                          98
                                                                100
'Estimated accuracy of the reported costs is -30% + 50% or less.
2A higher amount of chemicals was used during the demonstration test.  The reduced chemical consumption refers to
 33% of the demonstration test amount used.
''The stream factor indicates the  continuing  performance of the installation (a lower on-stream factor produces
 higher costs per ton of treated material).
4Rounded to whole dollars.

Source:  adapted from U.S. EPA 1989.
stabilized waste forms, and methods to improve bind-
ing. Engineering improvements such as providing ade-
quate mixing in the field  and assessment practices
such  as characterization of the raw wastes should be
further standardized and improved.
    in terms of scientific advancement,  it would be
desirable to have leaching tests that have  a sound
                   scientific background. Most presently used tests do not
                   provide fundamental infonmation about the leaching
                   process. Because waste-binder mixes are not required
                   to be specified to a great esxtent, test results from dif-
                   ferent waste-binder mixes can be  related only very
                   marginally.
                                                       31

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Chapters	

REFERENCES

     Barth, E.F. and McCandless, R.M. et al.  Treatability assessment planning guide for Solidification/stabiliza-
     tion of contaminated soils, U.S. EPA Risk Reduction Engineering Laboratory, October, 1989.

     U.S. EPA. Hazcon solidification process, Douglassville, PA - applications analysis report, EPA/540/A5-
     89/001, May 1989.

     University of Cincinnati. Solidification/stabilization treatablity assessment report, Kassouf-Kimmerling Bat-
     tery (KKB), NPLsite, September, 1990.
                                                 32

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Soil Vapor Extraction Technologies

Norma Lewis
United States Environmental Protection Agency
Office of Research and Development, Cincinnati, Ohio 45268
United States
ABSTRACT
   Soil vapor extraction (SVE) has been useful for soils contaminated with gasoline, solvents and other volatile
organic compounds, and some semivolatile organic compounds.

v^TS^tt^
Ser to the air and to condensed wastewater streams. It can also be used with m,crob.al treatment.
 also discussed.

 4.1  Introduction
    Soil vapor extraction (SVE), also known as in situ
 venting (ISV), can be a cost-effective  remediation
 process for soils  to remove volatile organic com-
 pounds (VOC's) and some semivolatile organic com-
 pounds (SVOC's) from the vadose zone.  The vadose
 zone is the subsurface soil zone located between the
 surface soil and the top of the water table.
    SVE technologies have been used to remove vapor
 from landfills since  the 1970's. During the 1980's, SVE
 was used extensively to remediate contaminated soil
 from leaking underground storage tanks.  Only recent-
 ly has SVE been used to remediate contaminated haz-
 ardous waste sites. This technology can be useful at
 sites where there  are  interferences or  obstructions,
 such as buildings  and highways that generally have
 sub-bases of porous material. In general, SVE is used
 in conjunction with other technologies since it transfers
 contaminants from soil and ground water to air and to
 condensed wastewater streams.
                                ^^
   The process of SVE is characterized by air being
drawn through the soil.  As the air passes through the
series of soil pores, it follows paths of lower resistance
(i.e., through  zones of high air  permeability).  Air,
which  is drawn  through pores that  contain con-
taminated vapor and liquids, carries the vapor away
(advent the vapors).  Contaminants will vaporize from
one or more of the condensed phases  (aqueous, ad-
sorbed) replacing the vapors that were carried away in
the air stream. Continued vaporization occurs to main-
tain the vapor-condensed phase equilibrium that was
established before the contaminants were removed.
This process will continue until all of the condensed
phase organics  are removed from the higher per-
meability soil. Contaminants  in lower permeability
zones will not be removed by advection since the air
stream will continue to flow through the higher per-
meability soil.  If the contamination is located some
distance from the air flow, the vapor must diffuse to the
air stream before it can be  removed.  The diffusion

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   Chapter 4
   process would then limit the rate of contaminant
   removal by the SVE process (U.S. EPA 1991 a).
    , I!ฃ.baslc Pnenฐmena controlling the performance
   of SVE systems are, therefore,  based on vapor
   transport mechanisms. The effectiveness of this vent-
   ing operation is dependent on three main factors:
     • The chemical composition of the contaminant

     ป The rate of the vapor flow through the vadose (un-
       saturated) zone

     •The flow path of the carrier vapors relative to the
       tocation of the contaminant (Hutzler, Murphy and
       Gierke 1988).

     Compounds exhibiting vapor pressures over 0 5
  cmi   Can be  most readilv extracted using SVE (U S
  EPA 1991a).  When expressed in terms  of the air-
  water partitioning coefficient, compounds that have
  values of dimensionless Henry's Law constants
  greater than 0.01  are more likely to be removed by
  
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                                                                   Soil Vapor Extraction Technologies
aggregation, and stratification.  Soil moisture content
or degree of saturation is important because it is easier
to extract vapor from drier soils. As the size of a soil
aggregate decreases, the time required for the dif-
fusion of the chemical out  of the immobile regions also
increases. Clayey or silty  soils may be effectively ven-
tilated by the usual levels of vacuum developed in a
soil vapor extraction system (Camp,  Dresser and
McKee 1987; Terra Vac 1987).  (The levels of vacuum
developed in SVE  systems can range from  7  to 760
mm Hg; however,  usual levels range from 50  to 130
mm Hg [Hutzler, Murphy and Gierke 1988].)
   It must be recognized that soils with high clay or
humic content generally provide high sorption potential
for VOC's and thus can inhibit the volatilization of con-
taminants (U.S. EPA 1991a).  The success of the soil
vapor extraction in  these soils may depend on:
   • The presence of more conductive strata as would
    be expected in alluvial areas

   • Relatively low  moisture contents in the finer-
    grained soils (Hutzler, Murphy and Gierke 1988).

   Application of  proper scientific and engineering
principles are necessary for reliable cost-effective sys-
tem design and to ensure desired treatment results.
Design  considerations include the number of installa-
tion wells, well spacing,  well location, and well con-
struction,  including the vapor treatment system.  To
date, a typical SVE system design consists of a single
extraction well network which feeds a common vapor
treatment system.  However, modular system designs
can be used to remove VOC's from  specific con-
taminated areas  or from areas with differing con-
taminant concentrations.  Modular  system design,
 although more capital intensive, allows for rapid chan-
 ges in operations; this allows for optimizing the sys-
tem.  It permits the shutdown of various segments of
the system once  remediation of that area has been
 completed, thereby reducing operating  costs.  It also
 allows the operation of one segment  of the system to
 be continuous while another segment is operated on
 an intermittent basis.
    In some cases, subsurface soil conditions can be
 modified to facilitate the  application of the SVE tech-
 nology. For example, it may be necessary to lower the
 ground water level to  enlarge the unsaturated zone;
 this would allow adsorbed volatile organics an oppor-
 tunity to vaporize.  At sites where the ground water is
 lowered, the extracted ground water may require treat-
 ment.  In some cases, application of techniques such
 as radio frequency (RF) heating can be considered to
 increase soil temperature; this would increase the
 volatility of the  contaminants and enhance con-
 taminant removal.
    In addition to extracting VOC's, SVE can be used to
 stimulate biodegradation of less volatile contaminants
 by supplying air (oxygen) to the subsurface soils at the
same time. Although oxygen is usually the rate limiting
parameter for aerobic biodegradation, other biological
factors, such as availability of nutrients, require
evaluation when considering using  SVE in this way.
(See the  chapter on microbial treatment, below, for
further discussion of this application.)
   After the contaminated vapors have been removed
from the subsurface soil, treatment may be required to
condense/concentrate or destroy the contaminants in
the air/vapor stream before it can be discharged into
the atmosphere. There are a variety of technology op-
tions available  for treating these vapors.   For vapor
streams with high concentrations of VOC's, condensa-
tion, thermal incineration, or catalytic oxidation are ap-
plicable options.  For more dilute vapor streams,
gas-phase activated carbon adsorption  can be used.
For very dilute vapor streams, if local regulations per-
mit, direct discharge into  the atmosphere  may be  al-
lowed.  Other methods, such as biological treatment,
ultraviolet oxidation, and dispersion also  have been
applied. The type of treatment chosen will depend  on
the composition and concentration of the contaminants
in the extracted vapor stream (U.S. EPA 1991 a).
    As operational experience with the SVE technology
has developed, it has been  learned that vapor/liquid
separators are frequently needed  prior to the vapor
treatment device.  Such separators need to be sized
large enough to provide ample protection for the vapor
treatment  system which follows.  This means that
vapor/liquid separators should be  slightly oversized,
rather than sized specifically for the downstream
equipment. The separated ground water and conden-
sate collected from the vapor treatment may have to
be treated as a hazardous waste.
    In the  remainder of this chapter, case studies are
presented to illustrate specific applications of the SVE
technology.   In addition, residuals and emissions,
costs, factors to consider for determining  applicability
of the technology, and the future  status  of the SVE
system are discussed.

4.2  Case Studies Chosen
    The case studies which are presented in the follow-
 ing discussion are intended to illustrate how SVE has
 been applied  to a wide range of site and soil condi-
 tions, as well as to various contaminant types and con-
 centrations. These include three case studies chosen
 for this NATO/CCMS Pilot Study and three additional
 studies from the United States. The latter are included
 to provide a  broader  information  base on the SVE
 technology.

 4.2.1 Case Study 4-A: In Situ Soil Vacuum
      Extraction, The Netherlands
    This case study has two sites, known as Site 1 and
 Site 2.  Site 1 was contaminated with solvents (up to
 2200 mg/kg d.m. toluene); Site 2 was heavily con-
                                                   35

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  Chapter 4
  laminated with gasoline (11,000 to  18,000 mg/kg
  dm.).  There were two objectives of  this project: to
  study the SVE removal effectiveness for contaminants
  located beneath structures as well asto study the ef-
  fectiveness of in situ biological degradation of residual
  organics stimulated by the perfusion of air into the sub-
  surface soils. The contaminants at both sites were in
  fine- to coarse-grained sands.  Details  of this case
  study are presented in Appendix 4-A.

  4.2.2 Case Study 4-B: Vacuum Extraction of Soil
       Vapor, Verona Well Field Superfund Site,
       United States
    The Verona Well Field site located in Battle Creek,
  Michigan had several distinct  contaminated areas
  within 100 acres.  During routine testing of the  city's
  drinking water  supply, volatile  organic  compounds
  (VOC's) were discovered in 10  of the  30 production
  wells. The contamination  plume  extended  over  an
  area of approximately 1.3 km2 (0.5  mi2)  and contained
  VOC concentrations as high as 1,800 ppb in  both the
  ground water and  soil.  The contaminated soil con-
  sisted of fine- to coarse-grained sand  with traces of
  clay and  silt. The objective of the project was to
  remove VOC's from the unsaturated zone within the
  contaminated boundary (Danko, McCann and Byers
  1990). To accomplish this, the ground water had to be
  lowered from 2 meters to 3  meters below the ground
 surface to enlarge the unsaturated zone.  An  abstract
 of this case study is presented in Appendix 4-B.

 4.2.3  Case Study 4-C: Venting Methods, Hill Air
       Force Base, United States
    The United States Air Force Engineering and  Ser-
 vices  Laboratory began a research project with  Oak
 Ridge National Laboratory to conduct a  full-scale test
 of In situ soil venting at a jet fuel (JP-4) spill site.  The
 site chosen for the test was a fuel  yard at Hill Air Force
 Base (AFB), Utah where a 100,000 liters (27,000 gal-
 lon) JP-4 spill had occurred.  The  site was selected for
 several favorable characteristics, including nearly ideal
 geohydrology, significant JP-4 contamination in the
 soil, logistical support, and the opportunity to under-
 take tests of different venting configurations.  A sum-
 mary of this case study is presented  in Appendix 4-C.

 4.2.4 Additional Case Studies, United States
   The following case studies are presented to typify
 other applications of SVE. These case  studies have
 been well  documented and  therefore provide com-
 prehensive evaluations of performance results for dif-
ferent SVE system configurations and site and
 contaminant conditions.
   Groveland Well Site,  Massachusetts.   A
performance evaluation of the  Terra Vac,  lnc:'s
vacuum extraction system was conducted during a
56-day demonstration test run at  a Superfund site in
  Groveland,  Massachusetts.   This site  was
  contaminated with degreasing solvent and cutting oils.
  Total contamination at the  site was  estimated at
  between 1,360 to  13,600 kg (3,000 and 30,000 Ib) of
  VOC's with much  of the heavy subsoil contamination
  located beneath a building (U.S. EPA 1989a).
     The objectives of this field test were:
     •To determine how well the technology would
      remove VOC's from the vadose zone

     • To assess effectiveness in various soil types

     • To correlate declining recovery rates with time

     • To correlate VOC concentration in soils with those
      in extracted vapors.

     This case study is summarized in Appendix 4-D.1.
     Paint Warehouse Fire, Dayton, Ohio. An
 undetermined quantity of paints and paint solvents
 escaped into the soils at a paint warehouse in Dayton,
 Ohio, as the result of a catastrophic fire.  Even though
 water was not  used to fight the fire, uncombusted
 material still penetrated the soil and spread through
 the unsaturated zone.  Less than six weeks after the
 fire, several VOC's  were detected in nearby city wells.
 Rapid VOC removal from the porous  soils in the
 vadose  zone  was needed to reduce further
 contamination of the ground water.
    The objective of this project was to document the
 use of SVE for the rapid removal of the VOC's.  In ad-
 dition, the  modular SVE system configuration
 developed for remediating the site was also the subject
 of study.  Refer to Appendix 4-D.2 for the case study
 abstract.
   Twin Cities Army Ammunitions Plant (TCAAP).
 This case study covers two site locations (Site D and
 Site G), at the TCAAP located  at  New Brighton,
 Minnesota.   Site D was a solvent leaching pit/burn
 area and covered an area of 0.2 hectare (0.5 acre).
 Site G consisted of landfill material contaminated with
 VOC's and some metals. The SVE systems used for
 remediating both of these sites began operation in
 1986 and are the longest operating and the largest
 SVE systems to date (U.S. EPA 1990a).  The criteria
 used in selecting these sites for study were:
   • Duration of the SVE system operations
   • Quality of the initial site characterization
   • Amount and availability of operational data
   • Willingness of site owners/operators to participate
     in the project
   • Site characteristics, such as soil  type, con-
     taminant type, and size.

   Two separate pilot systems were installed to test
several design and performance variables. System 1
was  designed to evaluate tetrachloroethylene TCE
                                                36

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                                                                    Soil Vapor Extraction Technologies
Table 4-1. Summary of SVE case study information.
Case study
The Netherlands
- Site 1
- Site 2
Verona

Hill AFB
Groveland
Dayton fire site
Principal
contaminant

Toluene
Petroleum products
VOC's

Jet fuel
TCE, MC
Toluene
Level of
contamination

2,200 nig/kg
11,000-18,000
mg/kg d.m.*
1 mg/kg

Not specified
TCE:2,500 mg/kg
Not specified
Soil type

Fine to coarse sand
Fine to gravel sand
Fine to coarse sand

Medium to fine sand
Medium sand to
gravel
Sandy soil with clay
Depth to
ground
water

7 meters
2 meters
7.5 meteirs

Not
specified
Not
specified
13.5 to 15
Vapor treatment

Activated carbon
Biological purification
Activated carbon then
catalytic oxidation
Catalytic incineration
Vapor-liquid separator,
activated carbon
Vapor-liquid separator
  TCAAP
  - Site D


  - Site G
TCE, TCA, toluene


TCE
VOC's: 50 to
8,000 mg/kg
VOC's: 22 to 960
mg/kg
Arsenal sand


Fill with underlying
clay
49.5 meters   Vapor carbon system


39 meters    Activated carbon
 *d.m.  = dry matter or dry weight (d.w.)
removal from soils with relatively low VOC contamina-
tion (less than 2.3 mg/kg). The second system was a
larger design to remove TCE with higher concentra-
tions up to 5,000 mg/kg.  Appendix 4-D.3 contains an
abstract of this case study.

4.3   Background of the Case Study Sites
      as a Group
   Table 4-1  summarizes the applications of SVE for
the various case studies.  The case study sites share
several common traits. They all involve the extraction
of volatile organic  compounds from  porous to
moderately porous vadose  zone soils.   The con-
taminated soil types found at the case study sites were
principally soils characterized by their high air conduc-
tivity.  In general, these were fine- to coarse-grained
sands, although other soil types including some silts
and clays were present.  Typically, the soil hydraulic
conductivities ranged between 10^ to 10-8cm/s.
   The sources of contamination varied between sites.
They  include releases of contaminants from under-
ground storage tanks, landfills, waste  handling prac-
tices, and contamination resulting from a fire.
   The contaminants requiring remediation included:
   • Chlorinated solvents
   ซ Gasoline
   • JP-4 (a jet fuel)
                                       • Nonhalogenated solvents.

                                       These classes of compounds are typical of those
                                    for which SVE is used.  They all have a majority of
                                    constituents which are highly volatile.
                                       These case studies also represent a diversity of
                                    site-specific conditions for SVE application.  For ex-
                                    ample, they illustrate the application of SVE for rapid
                                    remediation of sites recently contaminated to prevent
                                    ground water contamination; the remediation of sites
                                    with  contaminants which have resided in the environ-
                                    ment over  time; and the remediation of sites  which
                                    have obstructions such as buildings that limit the ap-
                                    plication of invasive techniques.  Additionally, they il-
                                    lustrate the differing  system  configurations,  using
                                    vertical and horizontal venting, that can be used. Also,
                                    these case studies demonstrate how SVE can be used
                                    to stimulate in situ biological degradation to  effect
                                    removal  of less  volatile contaminants as well as
                                    residual volatile contaminants remaining in the soil.
                                       The SVE processes were used at each of the sites
                                    as an integral part of  a treatment train.  One of the
                                    most significant differences between the SVE systems
                                    presented involves the treatment techniques used for
                                    the off-gases.  Depending  on the contaminant con-
                                    centrations  in the extracted vapor stream, the treat-
                                    ment of the  off-gases included:
                                       •  Direct discharge for air streams which contained
                                        very dilute VOC concentrations
                                                  37

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Chapter 4	

   • Vapor phase activated carbon for low volume/low-
    to-moderately contaminated air streams

   • To catalytic oxidation for more highly con-
    taminated air streams.
 4.4  Performance Results
   For each of the case studies performance results of
the SVE system were collected. The following discus-
sion presents these results, and the key design criteria
and analytical procedures used in their determination.

4.4.1  Analytical Procedures
   To evaluate the performance of SVE systems, it is
important to quantify the amount of VOC's removed,
the amount of these contaminants remaining in the
soil, and the time for remediation.  Further, additional
data is needed for operating the air pollution  equip-
ment used to treat the extracted vapors. The following
discussion illustrates some of the techniques used for
accomplishing these tasks.
   The techniques used at the Groveland site typify
the procedures used to measure VOC removal.  The
quantification of VOC's removed was done by measur-
ing:
   ปThe  gas volumetric flow  rate  by rotameter,  and
    wellhead  gas VOC  concentration by  gas
    chromatography (GC)

   "The  amount of  VOC's adsorbed in the activated
    carbon canisters by desorption into CSg, followed
    byGC.

   VOC flow rates were measured and tabulated for
each well section separately.
   In  general similar approaches were used in all of
the case studies to determine residual contaminants in
the subsurface soils. These included the collection of
soil, soil gas, and ground water samples, and analyz-
ing these samples for the parameters of concern. At
the TCAAP site soil gas probes were  used in
boreholes drilled during the initial site assessment to
determine the residual soil gas in the subsurface.  Be-
cause these were already drilled the number of
boreholes required later for assessing the SVE perfor-
mance was reduced, thereby reducing costs as-
sociated with this testing.
   To collect data about the extracted vapors, vapors
extracted from both  SVE systems at the TCAAP were
continuously monitored for moisture content, tempera-
ture and pressure.  Similar data was collected in most
of the case studies which  required vapor treatment.
Additionally, air emissions were monitored  throughout
the operation, initially on a daily basis, and then on a
weekly basis.  The frequency of  sampling  was ad-
justed when the  data reflected trends indicating a
stability of the extraction process.  To gain an under-
standing of the SVE process, in addition to  evaluating
the performance of the system, other procedures were
used at The Netherlands Site 1.  These were the
modeling of the SVE action duration, the study of the
horizontal versus  vertical aerodynamical conductivity
of the soil, and the measurement of bacterial activity.
For the duration factor, the input parameters were the
estimated airflow in the subsoil, the sorptive properties
of the subsoil in relation to the contaminants, and the
physical/biological properties of the  contaminants at
soil temperature.  Air flow and tracer velocity measure-
ments  in relation to  the  applied negative pressure
gradient in the subsoil were made for use in the model.
At this site,  the horizontal directional aerodynamical
conductivity of the soil was found to be  about  150
meters per day (500  ft/d); in the vertical direction, it
was about 70 to 90 meters per day (230 to 300 ft/d).

4.4.2  General Effectiveness of the SVE Process
   SVE worked best at sites contaminated with VOC's
having Henry's Law constants greater than 0.01 or
vapor pressures greater than 0.5 mm Hg. However,
less volatile constituents can also be removed by SVE,
but removal efficiencies are reduced as the volatility
decreases.  SVE  has  been shown to remove VpC's
from fine- to coarse-grained sands with permeabilities
ranging between  10-3 to  10'8 cm/s. Although per-
meability (hydraulic conductivity) is frequently used as
a criterion for SVE applicability, air-filled porosity of a
soil is a more important factor.
   In general, SVE has been demonstrated to be ef-
fective for the removal of VOC's from vadose zone soil
up to depths of 180 meters (600 ft). Soil with moisture
content up to 30 percent can be effectively remediated.
(Ground water levels  can be  lowered to increase the
vadose zone.) Soils with high clay and/or  humic con-
tent will tend to adsorb the VOC's present and thereby
slow vaporization. Thus adsorption can affect the level
of remediation obtainable in such soil; that is, the soil
cleanup levels may not be achievable by SVE alone.
   Johnson, et al. (1990) suggest that SVE is capable
of removing approximately 90 percent of the volatile
contaminants with a vapor pressure  greater than 0.5
mm Hg.  This rule of thumb is generally supported by
the case study data and provides a  starting  point for
estimating how much material can be removed  and
how much will remain in the subsurface.
   To date,  insufficient data exists to permit develop-
ment  of empirical relationships for VOC  removal ef-
ficiencies for specific contaminants in various soil
types.  Based on the case studies presented, the mass
removal rates vary greatly from site to site. The mass
removal rates were observed to range up to 2300 kg/d
(5000 Ib/d).  Average mass removal rates typically
ranged between 5 and 30 kg/d. The rate at which con-
taminants were removed over the project life differed.
In several of the case studies, there was an initial
                                                 38

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                                                                   Soil Vapor Extraction Technologies
 sharp decline in the VOC mass removal rate followed
 by a period of gradual decline; this ultimately leveled
 off as residual cpntaminant  concentrations ap-
 proached zero. It is believed that this is characteristic
 behavior for sites where the  contaminants  have
 resided in the subsurface for some time and in which
 the moisture content of the soil is low. In other cases,
 mass removal  rates increased over time and then
 declined gradually before leveling off as the VOC con-
 centrations  in the extracted vapor approached  zero.
 Preliminary indications are that this occurs at sites
 where the  moisture  content is  high and the soil
 porosity is low. Since only limited data exist on SVE
 applications, the performance  results for the  case
 studies can  only provide an indication of the effective-
 ness of SVE applications for given contaminants and
 specific site  conditions.
   Operationally, the Groveland case study indicates
 that once the VOC concentration in the extracted
 vapor leveled off (as it approached zero),  the extrac-
 tion process can be terminated for approximately two
 days and then restarted.  (The time required to reach
 this leveling-off point was estimated to be  150 to 200
 days, based on modeling.) By stopping the extraction
 process, equilibrium in the air spaces can be  rees-
 tablished.  If, when the extraction process is begun
 again, the VOC concentration does not increase above
 the concentration which was observed when the
 process was stopped, it can  be concluded that the
 maximum removal efficiency achievable by the SVE
 process has been obtained. If, however, an increase
 in the VOC concentration is observed in the extracted
 vapor, it can be concluded that vaporization is still oc-
 curring.  At this point, intermittent operation  of the SVE
 system can  be used until the concentration of the ex-
 tracted vapor does not increase after the process has
 been stopped.

 4.4.3 Removal of Nonhalogenated Solvents
   Performance results from Site 1  in The Netherlands
 show that,  within four months  of operation, ap-
 proximately 580 kg (1300 Ib) of toluene was withdrawn
 from the  contaminated area.  Initial concentrations of
 toluene in the fine- to coarse-grain sand ranged up to
 2200 mg/kg.  Concentrations of up to 8000 mg of
 toluene/m3 were measured in the withdrawn soil vapor
 (up to 40 g/m3 in a specific extraction well).
   At the Dayton Site, the soil volume to  be treated
 was divided  into four cells, based on the air flow rate
 which could  be provided by a  pumping unit.  Each of
 the four cells was brought on  line for two week inter-
 vals.  The  system recovered 1690  kg (3720 Ib) of
 VOC's during the first 73 days of operation.  After 56
weeks of operation, over 3600 kg (8000 Ib) of VOC's
 had been recovered from the site.   By April 1988,
composite off-gas VOC measurements had fallen to
 less than 1  ppm.  At the same time, VOC concentra-
tions  in the  unconfined aquifer  had, for almost two
 months, been at nondetectable levels for all hydrocar-
 bon species identified prior to treatment.  By June
 1988, all  off-gases extracted  from the shallow, un-
 saturated  soil were below 1 ppm. All  perched water
 extracted  from the vacuum wells yielded VOC con-
 centrations below action levels accepted by Ohio's
 EPA and the cleanup activities were halted.  (Ground
 water VOC action levels were established for the
 ketones as follows:  acetone,  810 ng/L;  MIBK, 260
     ; and MEK, 450 ng/L.)
 4.4.4 Removal of Gasolines and Jet Fuels
   At The Netherlands Site 2, the soil was heavily con-
 taminated with 11,000  to 18,000  mg/kg petroleum
 products.  Over the first year of operation, the SVE
 system extracted approximately 1 ,900 kg (4200 Ib) of
 volatile organics from the soil, and approximately 800
 kg (1800 Ib) was broken down in the soil by microbial
 action;  (thus, a total of nearly 2,700 kg (6000 Ib) of
 gasoline was removed or broken down). Nine months
 after beginning the SVE process,  the  soil-air vapor
 withdrawal rate was increased from 25 to 50 m3/h  (15
 to 30 cfm). The concentration of volatile gasoline com-
 pounds was 3 g/m3. After an additional ten weeks,  the
 SVE air extraction rate was increased once again to 63
 m3/h (37 cfm). To keep the concentrations of the con-
 taminants in the extracted-air at about the same level,
 the extraction rate was increased during the clean up
 period.  This was necessary for the  efficient operation
 of the biological treatment plant.  There were no limita-
 tions caused by the geological situation.
   At Hill AFB, approximately 50,000 kg (110,000 Ib)
 of JP-4 hydrocarbons had been extracted in the vented
 soil gas between start-up in December 1988 and Oc-
 tober 1 , 1989. The contaminated area was determined
 to be 37 meters by 37 meters (122 ft by 122 ft) to a
 depth of 15 meters (50 ft) below the land surface. The
 highest soil gas  hydrocarbon  concentrations had
 dropped from 1 79 percent of the lower explosion limit
 (LEL) in February 1989, to 88  percent LEL  in April
 1989.  Also, the concentration of hydrocarbons in  ex-
 tracted  gas from the entire venting system dropped
 from 38,000 ppm  hexane equivalent in  December
 1988, to 500 ppm hexane equivalent in October 1989
 (Downey and Elliott 1990).
   During these 9 months of operation at Hill AFB,
 SVE volatilization removed 47,500 kg (105,000 Ib) of
 VOC's and another 6,800 to  9,000 kg (15,000 to
 20,000  Ib)  were converted by biodegradation.  Soil
 hydrocarbon levels were reduced by 95 percent, and a
 corresponding drop of 99 percent was noted in soil gas
 levels.  Only 7 percent of the post operation soil
 samples exhibited total  hydrocarbon levels greater
than the 100 mg/kg cleanup criterion used.    \
   At the Verona Well Field site, VOC's at concentra-
tions as high as 1800 mg/kg were located in a plume
covering approximately 1 .3 kma (0.5m2) ;and extending
                                                 39

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 Chapter 4
 downward from the surface to 7.5 meter (25 ft).
 Results described here come from both the pilot and
 full-scale operation at the Verona Well Field site.  The
 pilot system, which operated for 69 hours during a 2-
 month period beginning in November 1987, extracted
 about  1360 kg (3000 Ib) of VOC's from the vadose
 zone.  The full-scale SVE system began operation in
 March 1988 and, after 25 months  of operation, had
 removed approximately  19,500 kg (43,000 Ib) of
 VOC's. The TVOC's extracted per day dropped from
 49 kg/d (108 Ib/d)  initially to less than 45  kg/d (100
 Ib/d) by May 1990.  By September 1990, this amount
 became less than 2.2 kg/d (5 Ib/d).

 4.4.5 Removal of Halogenated Solvents
   At the Groveland Well site, analysis indicates that a
 total of 588 kg (1,297 Ib) of VOC's were extracted over
 the 56-day test period.  The soil porosity ranged from
 40 to 50 percent, and was nearly the same for both the
 clay and sands over the 7-meter (24 ft) depth of the
 wells.   The permeability/hydraulic conductivities
 ranged from 10'4cm/sforthe sands to 10-8cm/sforthe
 clays.   The majority of the contamination resided
 above the clay layer. Table 4-2 shows the reduction
 of weighted average TCE levels in the soil during the
 56-day demonstration test.  This weighted average
 level was obtained  by averaging soil concentrations
 obtained every 0.9 meters (2 ft) by split spoon sam-
 pling methods over the entire 7-meter (24-ft) depth of
 the wells.  The largest reduction in TCE soil concentra-
 tion, about 95 percent, occurred in Extraction Well 4,
 which  had the  highest initial level of contamination.
 The majority  of the soil borings taken after the test
 gave VOC levels that were not detectable (U.S. EPA
 198 9 a).
   The two SVE systems at TCAAP have shown the
 ability to remove significant quantities of VOC's from
 the soils. The Site D system removed a total of 49,200
 kg (108,460 Ib) of solvents between January 1986 and
 May 1990; and VOC concentrations at Site D
 decreased generally four orders of magnitude.  The
 pretreatment concentrations of TCE varied widely over
 the site and ranged from nondetectable up to 7 million
 jig/kg.   Of the 26  post-treatment soil samples col-
 lected, only five detected TCE  above the  detection
 limit; the highest concentration was 29 u.g/kg.
   TCAAP Site D soils consist of predominantly silica
 sand with a porosity ranging from 36.7 to 39 percent
 and permeabilities ranging between 5.7 x 10'4 and 3.5
x 10'3 cm/s. The soil moisture content ranged from 1.7
to 14 percent.  Over the first four months of operation,
the mass removal rate ranged from 7 to 16 g/d. After
four months of operation, a deep vent was installed, 46
 meters (150 ft), and removal rates increased to 24 g/d.
At this  site, because the soil was silica sand, soil ad-
 sorption did  not play a  significant role; thus, the
volatilization phenomenon was the rate controlling
factor.
Table 4-2. Reduction of weighted average TCE levels
          in soil, Groveland Weli Site (TCE concentra-
          tion in mg/kg).

Extraction Well
1
2
3
4
Monitoring Well
1
2
3
4
Pre-
treament

33.98
3.38
6.89
96.10

1.10
14.75
227.31
0.87
Post-
treatment

28.31
2.36
6.30
4.19

0.34
8.98
84.50
1.05
Percent
reduction

13.74
30.18
8.56
95.64

69.09
39.12
62.83
- '
Source: U.S. EPA April 1989
   VOC concentration in TCAAP Site G soils and fill
materials  decreased generally two orders of mag-
nitude.  The pretreatment concentrations varied from
non-detectables up to 400,000 ng/kg of TCE.  Many
samples were in the 10,000 to the 100,000 M9/kg
range. As of May 17, 1990,,an estimated 45,000 kg
(100,000 Ib) of VOC's had been removed from Site G
since remediation began in January 1986.  Of the 245
post-treatment soil samples collected, only seven indi-
cated TCE concentrations above the detection limit
with the highest concentration being  420 u.g/kg (U.S.
EPA1990a).
   Initially, the removal rates at Site G showed a sharp
decline and a more gradual decline during later opera-
tions. Mass removal rates, beginning  at approximately
2300 kg/d (5000 Ib/d), decreased to 450 kg/d  (1000
Ib/d) within 14 days.  After 76 days, mass removal
rates had dropped to approximately 90 kg/d (200 Ib/d).
They then dropped to 23 kg/d (50 Ib/d) after 195 days,
and to 0.45 to 4.5 kg/d (1 to 10 Ib/d) after 1060 days of
SVE operation.
   The soil types present in the landfill area (Site G)
were heterogeneous and consisted of fill material, con-
struction debris, office trash and industrial waste.  As a
result, adsorption of contaminants onto landfill material
played a more important role in the release of the VOC
under SVE application.

4.4.6 Usefulness for Enhancing In Situ
      Biodegradation
   Another important mechanism of remediation using
SVE is biodegradation  which can directly affect the
                                                 40

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                                                                   Soil Vapor Extraction Technologies
amount of residual organic contamination remaining in
subsurface  soil.  The increased oxygen levels in the
soil gas due to infiltration of atmospheric air can stimu-
late biological activity.  In the case studies which
evaluated this effect, the SVE process  enhanced in
situ biodegradation of nonhalogenated materials such
as toluene, gasoline, and aviation fuels.   In the other
case  studies, the  effect SVE may have had  on
biodegradation was not evaluated.  However, it would
be expected that, if microbial populations and sufficient
nutrients were present, degradation may have been
occurring simultaneously with vaporization. Thus, in
recent spills where microbial populations have not had
a chance to develop, it is less likely that SVE will
stimulate biodegradation than at sites where the con-
taminants have resided in  the subsurface for an ex-
tended period of time.
   At Hill AFB,  it was found that bioactivity was
responsible for 13 to 17 percent of the total hydrocar-
bon removal during the first 70 days of venting.  Over
the 9 months of operation, a total of 6,800 to 9,000 kg
(15,000 to 20,000 Ib) were converted by biodegrada-
tion.  Over the  study period, the percent of total
hydrocarbon removal attributable to biodegradation
remained essentially the same.
   Similarly at the two sites  associated with The
Netherlands case study, biodegradation  was used to
enhance remediation efforts.  At Site 1, under  aerobic
conditions, toluene and other hydrocarbons  were
found to biodegrade in situ under the  conditions
provided by the  SVE perfusion of air.  The  rate of
biodegradation of toluene, per kilogram of soil, was es-
timated to be approximately 2 mg C/kg/d (Spuy et al.
1990; U.S. EPA 1990b).  At Site 2, in situ biodegrada-
tion of the less volatile fraction of the gasoline was en-
hanced by  application  of the SVE process.   It was
estimated that, over the first year of operation, ap-
proximately 800 kg (1800 Ib) of  the gasoline con-
stituents in the soil were biologically degraded  without
the addition of nutrients.
   Although halogenated solvents are not as readily
biodegradable as nonhalogenated solvents, they still
can be broken down in the subsurface environment.
No observations  of subsurface biological activity were
noted, or sought,  in the case studies  involving
halogenated VOC's. Those case studies for which an
assessment of in  situ bioremediation activities as-
sociated with SVE applications have been conducted
involved nonhaloaenated volatile organic con-
taminants, such as those found in solvents and fuels

4.5  Residuals and Emissions
   Air emission problems could be created by  using
the SVE system  if the vapor stream were not treated.
In some cases, vapor treatment may not be required
for systems that  produce a very low emission rate of
easily degradable chemicals.  The decision to treat
vapor must  be made in conjunction with air quality
regulators.   If vapor treatment systems are required,
technologies available for this  purpose include liq-
uid/vapor condensers, gas-phase granular activated
carbon, incinerators, and catalytic converters.
   Liquid/vapor condensers (separators) are generally
used for  raw material recovery and/or as a pretreat-
ment device for removing VOC contaminants prior to
other control devices.  For SVE systems, condensers
are used  to protect blowers and increase the efficiency
of the vapor treatment system. Condensers are also
used  as  the primary control device for emission
streams with concentrations greater than 5,000 ppm.
Variability in VOC concentration will decrease the
overall control efficiencies olf condensers. Removal ef-
ficiencies for condensers are typically less than that for
the other three techniques, ranging from about 50 to
80 percent using chilled water.  Removal efficiencies
approaching 90 percent are possible using subzero
refrigerants such as ethylene glycol or freon, but this
significantly increases capital and operating  costs
(U.S. EPA 1989c).  The entrained ground water and
condensate brought up through the SVE system may
have to be treated as a hazardous waste, depending
on the types and concentration of the contaminants.
   Once  entrained or condensed material has been
removed  from the vapor stream, other treatment tech-
niques can be used to remove the remaining VOC's
from the  vapor stream.  Carbon adsorption is most
commonly applied as a pollution control technique
and/or for solvent recovery.  It can be applied to very
dilute mixtures of VOC's but typically performs better
with concentrations exceeding 700 ppm. Carbon ad-
sorption units can be designed to achieve efficiencies
of 99 percent.  Actual efficiencies may be somewhat
lower, ranging from 60 to 90 percent, depending upon
inlet concentration and factors such as stream
temperature, moisture content (relative humidity), and
maintenance. Usually, dehumidification is necessary if
high humidity  (i.e., relative humidity greater than 50
percent)  is present.  Cooling the stream is usually re-
quired if  the stream  temperature exceeds 65 ฐC (150
T).  Carbon adsorption can usually handle variable
input stream conditions. Removal efficiencies are not
affected when flow rates arid concentrations vary sig-
nificantly. Carbon adsorption performs best with com-
pounds having a molecular weight between 50 and
150 g/mol, or organic compounds containing between
four to ten carbon atoms.
   If air  emissions control or vapor treatment  is re-
quired for an SVE installation, a vapor phase granular
activated carbon (GAG) adsorber system probably will
be the most practical system, depending on chemical
emissions rates and VOC kivels.  Gas-phase GAC re-
quires heating of the extracted air to control the relative
humidity  in order  to optimize the carbon usage rate.
As the fraction of water increases, the capacity for the
target chemical decreases and the carbon  replace-
                                                 41

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 Chapter 4
 ment rate increases.  The spent carbon may be con-
 sidered as a hazardous waste depending on the con-
 taminants (Hutzler, Murphy and Gierke 1988).
    Two different methods are used to apply carbon ad-
 sorption to SVE systems. One method uses  a fixed
 bed regenerative system allowing reuse of the carbon
 bed, while the other uses carbon canisters which can-
 not be reused.  Fixed bed systems have higher capital
 and annualized costs relative to carbon canisters. As
 such, fixed bed systems are generally used when high
 gas volumes require treatment,  and cleanup duration
 is extended. Carbon  canister systems are  generally
 used for low gas volume  extraction processes. (U.S.
 EPA 1991 a).
    Since carbon adsorption is a conventional technol-
 ogy for the removal of organics  from a vapor stream,
 little emphasis was placed  on  evaluating its  perfor-
 mance in the case studies. Only when the carbon ad-
 sorption systems were found to affect the overall cost
 of the remediation were they compared, in economic
 terms, with other vapor treatment systems.
    Thermal incineration is widely used to  control a
 variety of emission streams  containing VOC's.  This
 treatment is capable of handling a broader range of
 compounds compared to  other techniques.  Destruc-
 tion efficiencies exceeding 99 percent for VOC con-
 centrations  above 200 ppm, as well  as destruction
 efficiencies  exceeding 95  percent for concentrations
 as  low as 50 pprn, are obtainable. However, this sys-
 tem is not well suited for streams with variable flow
 rate conditions since this tends to change mixing and
 residence times from design values, and therefore
 lowers combustion efficiency. Therefore, the system
 performs best with relatively constant flow rates and
 with dilute mixtures of VOC's in  the air stream. Sup-
 plemental fuel  is required to maintain combustion,
 especially if treating dilute VOC streams. This tends to
 increase operating costs and makes this technique
 less desirable (U.S. EPA 1989c).
    Catalytic converters  are similar to thermal in-
 cinerators in design and operation except that they use
 a catalyst to enhance combustion. The catalyst allows
 the reaction to take place at lower temperatures, there-
 by  reducing the amount of supplemental fuel  neces-
 sary relative to thermal incineration.  Typical  design
 efficiencies for this technique are usually around 95
 percent, although 99 percent  is quoted in some  cases.
Actual efficiencies may be somewhat lower  (e.g., 90
percent) depending upon  operational  and  main-
tenance practices.  This technique is not as broadly
 applicable as thermal incineration because the catalyst
 Is more sensitive to pollutant  characteristics and
process conditions.  In addition,  compounds such as
 halogens (e.g., chlorinated hydrocarbons), lead, mer-
cury, tin, zinc,  and phosphorous may damage the
catalyst and severely affect performance. Therefore
catalytic converters are not usually selected as a VOC
 control system when metals and/or halogenated con-
 taminants are present.  This method is usually chosen
 for nonhalogenated compounds over thermal incinera-
 tion for SVE sites because of lower  operating costs
 (U.S. EPA1989C).
    In two of the case studies, catalytic oxidation was
 used to destroy the organics present  in the extracted
 vapors. At the Hill AFB demonstration, during the 9-10
 month operation of the  SVE system, 95 percent of the
 vapors extracted were passed through one of two
 catalytic oxidation units. The first unit was a 14 nrvVmin
 (500 ft3/min) fluidized bed unit that operated for eight
 months. The  second was a 28 m3/min (1000 ftS/min)
 fixed bed unit  that used a precious metal catalyst and
 was operated  for six months. There  was a period of
 four months when the two units operated together to
 treat the venting off-gases.   The  fixed bed  was
 operated between 240  and  330 ฐC (470ฐ and 625 ฐF)
 while the fluidized bed unit was operated between 330
 and 370 ฐC (625 and 700 ฐF).
    Results showed that the fluidized bed unit had an
 average 89 percent destruction efficiency and the fixed
 bed unit had a 97 percent  destruction efficiency.  In
 this study, it was found that the fixed bed system could
 not handle the large  flow rate of highly concentrated
 VOC's.  Because the process  is one of oxidation or
 burning of the contaminants, the heat released in the
 process caused the fixed beds to  get so hot that the
 end of the bed would melt.  Temperature safety con-
 trols can be  used to prevent  this from happening.
 However, such controls limit the amount of con-
 taminant that can be  treated. Because of better heat
 transfer, the fluidized bed unit can handle the higher
 concentration flow rates.  Its disadvantage is that the
 system needs a catalyst.   At the Hill AFB site, ap-
 proximately 70 kg (150 Ib) of catalyst were added to
 the reactor over the eight month operation.
   The Air Force, at Eglin AFB in Florida, conducted a
 pilot-scale catalytic oxidation unit test on fuel con-
 taminants which had been  air stripped from  ground
 water.  The unit used an electric preheater to raise the
 inlet gas temperature to 540 ฐC (1000 *F) before pass-
 ing it through a precious metal fixed bed catalyst reac-
 tion chamber.  Although this technology  resulted in
 on-site destruction  of the organic  contaminants,
 hydrogen sulfide that was stripped out of the water
 caused a chemical reaction in the catalytic oxidation
 unit which effectively  and rapidly deactivated the
 catalyst (U.S. EPA November 1990).  This illustrates
the need for a good understanding of the chemical
constituents comprising the  vapor stream and for as-
sessing the impact of those  constituents  on the
catalyst.
   Catalytic oxidation was also used at the Verona
Well site when activated carbon costs  became exces-
sive.  From March 1988 to January 1990, the VOC
contaminants were removed from the vapor stream by
                                                 42

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                                                                   Soil Vapor Extraction Technologies
activated carbon adsorption.  At that time, the carbon
vapor extraction treatment system was replaced by an
on-site catalytic oxidation technology for cost reasons.
(Carbon adsorption costs were three times as great as
that for catalytic oxidation.)  Of the VOC's present in
the vapor stream,  TCE proved to be the hardest  to
destroy by this technology and therefore was used as
the indicator of destruction efficiency.  At 415 *C (780
ฐF), average TCE discharge concentrations of 204 ppb
were  found  in the  stack emissions-this is about 60
percent of the discharge limit.  At 446 ฐC (835 ฐF), the
level of TCE dropped to 35 ppb. As a result of these
findings, the catalytic oxidation system was operated
at 427 ฐC (800 ฐF) without any difficulties.
   In  summary,  vapor phase activated  carbon  was
used  for extraction systems where there was a low
volume of gas extracted and remediation time was ex-
pected to be short.  Limited data indicated removal ef-
ficiencies of 90 to 99 percent. Costs for activated
carbon systems used to treat air streams with  high
VOC  concentrations were found to be excessive.  The
major cost factor attributable to the high costs was as-
sociated  with regeneration.   In such cases, catalytic
oxidation, an alternative to vapor-phase activated
carbon, was found to be a more cost effective vapor
treatment technique.  In particular, at the Verona  Well
Field  site, it was shown that catalytic combustion of off
gases could reduce the emissions to below 100 ppb
(the allowable discharge level) at approximately one
third the cost.
   As noted previously, other residuals produced can
include aqueous waste streams from  liquid/vapor
separators and ground water extracted  to lower the
water table.  Conventional treatment  techniques  in-
cluding biological treatment  and/or activated carbon
can be used to  treat  these waste streams.  At The
Netherlands Site 2, however,  these aqueous waste
streams were treated with the vapor stream in a com-
mon biological treatment system.
   In this single treatment process (referred to  as a
biological purification system), the gasoline vapor with
an organic loading of approximately 210 g/h  was
treated along with  extracted ground water which had
an organic load of approximately 8 g/h  (15 m3/h at 0.5
g/m3)(U.S. EPA1990b).

4.6   Factors to Consider for Determining
       Applicability of the Technology
   One must "realize that there are practical limitations
on the final soil contamination levels  that can  be
achieved with soil venting systems.  Knowledge of
these limits is necessary to realistically set cleanup
criteria and design effective  venting systems. Maxi-
mum efficiency of a venting operation is limited by the
equilibrium partitioning of contaminants  between the
soil matrix and vapor phases. The maximum removal
rate is achieved when the vapor being removed  from
an extraction well  is in equilibrium with the con-
taminated soil" (Johnson et al.  1990).  Models for
predicting this maximum removal rate have  been
presented by Mariey and Hoag (1984) and Johnson et
al. (1988).  The former considered only compositions
in a residual free-phase, while the latter  also con-
sidered the effects of sorption and dissolution proces-
ses (Johnson et al. 1990).
   Venting also presents the possibility of inducing
migration of off-site contaminant vapors toward the ex-
traction wells.  If this occurs, the scope, cost and time
for remediation can  be significantly impacted, due to
the influx of these off-site contaminant vapors. A pos-
sible solution to this problem is to install a vapor bar-
rier, using vents, at the perimeter of the contaminated
zone.  Alternatively, by  allowing vapor flow into  the
perimeter ground water monitoring wells, a vapor bar-
rier would be formed to  block the migration of these
off-site contaminants. In some situations  it may be
necessary to  install passive air injection wells, or
trenches (Figure 4-2a) (Johnson et al. 1990).
   Application of vacuum extraction systems may also
cause a water table  rise.  When contaminated soils lie
just above the water table, they can become saturated
by the rise in the water table. Where the water table
rise equals the vacuum  (that point expressed as an
equivalent water column height, i.e., in mm H2O) the
maximum rise occurs. The recommended  solution is
to install a  dewatering  system, with ground water
pumping wells located as dose to the vapor extraction
wells as possible.  The dewatering system must be
designed to ensure that contaminated soils remain ex-
posed to vapor flow (Figure 4-2b) (Johnson  et al.
1990).
   Uncertainties  which  appear to  limit SVE include
lack of precise information on site heterogeneities and
contaminant  location;  inability to predict cleanup
schedules; and uncertainty regarding the ability of the
technology to  achieve cleanup goals.  These areas of
uncertainty must be recognized when conducting
treatability tests,  pilot testing, when performing
detailed analysis of alternatives, and when implement-
ing the technology for  site remediation (U.S. EPA
1991b).  Figure 4-3  (Johnson et al. 1990) provides a
guideline for deciding  if a soil vacuum  extraction
process is applicable to a particular site.
   Table 4-3 summarizes the factors that limit SVE ap-
plication.  It discusses reasons for the potential limita-
tions, presents the  data collection  requirements that
identify these limitations, and indicates at which phase
of the technology selection process it becomes impor-
tant.  In the United States, this process consists of:
   • A prescreening phase, where all possible ap-
     propriate technologies for the given contaminants
     are identified
                                                  43

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 Chapter 4
          Vapor
        Extraction
            Veil
                                                      (b)
    OH-site
Contamination
Unsaturated
 Soil Zone
  Vapor
Extraction
   Well
                      Passive Air Injection Well
                               or
                Perimeter Ground Water Monitoring Well
                                                       Saturated
                                                       Soil Zone
                                    Water Table upwelling
                                     Caused by Vacuum
     Source: Johnson et al. 1990.
 Figure 4-2. Two types of soil venting systems, (a) Use of passive vapor wells to prevent migration of off-site con-
          taminant vapors, (b) Water table rise caused by the applied vacuum.
   ป A remedy screening phase, where the number of
     technologies considered is reduced to a manage-
     able number based on site-specific conditions

   • A remedy selection phase, where the remaining
     viable technologies are evaluated for technical
     and economic merits to permit technology selec-
     tion

   ปA remedy design phase,  which involves those
     treatability studies and design activities needed to
     permit the construction of the facilities.

   Some requirements apply before the prescreening
phase is initiated.  These consist of the compilation of
data from literature and data base sources, and from
sfte-specific assessments, investigations, and charac-
terizations.   (See related discussion in the chapter
below on selecting remedies at a complex hazardous
wsate site.)

4.7   Costs
   Treatment costs for sites depend on various condi-
tions such as:
   * Site size, and extent of contamination
   ซ Regulatory requirements for permits, and opera-
    tion
   ซ Site-specific and chemical-specific conditions
   ซ Site cleanup criteria.

   Therefore, costs should be estimated on a case-by-
case basis.
   Treatability data collected can be very  useful in
generating  cost estimates.   These estimates  will  be
more precise when they are based on pilot-scale data.
Table 4-4 relates data  collected during treatability
                  studies to the major components affecting SVE costs.
                  The cost of pumping which is associated with the num-
                  ber of wells, can be significant.  Instrumentation, and
                  analytical costs for monitoring the process will also af-
                  fect system costs (U.S. EPA 1991 a).
                     In general, a cost analysis addresses both capital
                  costs, and operating and maintenance costs.  Capital
                  costs  include both depreciable and  nondepreciable
                  cost elements. Depreciable costs include direct costs
                  for site development, capital equipment, and equip-
                  ,ment installation.  Indirect costs include:
                     • Engineering services prior to construction
                     • Administrative tasks, such as permitting
                     • Construction overhead and fee
                     ป Contingencies.

                     Nondepreciable costs include those direct costs as-
                  sociated with purchased  engineering and technical
                  services for the development of operating procedures
                  manuals and operator training, etc. (U.S. EPA 1989a).
                     Operating and maintenance costs include variable,
                  semivariable, and fixed  cost  elements.  Variable
                  operating cost  elements include utilities and
                  residual/water disposal costs.  Semivariable costs in-
                  clude unit labor and maintenance costs, and laboratory
                  analyses.  Fixed costs include depreciation, insurance,
                  and taxes (U.S. EPA 1989a).
                    An economic model for the Terra Vac vacuum ex-
                  traction system at the Groveland Well site is presented
                  in Table 4-5.  This model illustrates the relative dis-
                  tribution of capital, operating and maintenance and
                  fixed costs and the major elements of each. The costs
                  presented are based  on the transportable skid-
                  mounted unit that may not be permanently installed at
                  the site.            ,  -
                                                  44

-------
                                                                             Soil Vapor Extraction Technologies
         No
         No
    No
    further
    action
         No
                                Process
                          Leak or spill discovered
                     Emergency response & abatement
                           Site characterization
                           Exposure assessment
                            Regulatory review
                         Yes
Define  clean-up objectives
                        Screen treatment alternatives
                           Air permeability test
                          Ground water pump test
                               System design
                      System operation & monitoring
                                                          Output
                                              Background review

                                              Site characteristics:

                                              Subsurface  characteristics
                                              - Soil stratigraphy
                                              - Characteristics of distinct soil layers
                                                (permeability estimates, soil types)
                                              - Depth to ground water
                                              - Ground water
                                              - Seasonal water table fluctuations
                                              - Aquifer permeability (estimate)
                                              - Subsurfact  & above-ground temperature

                                              Contaminate delineation
                                              - Extent of free-phase hydrocarbon
                                              - Extent of soluble contaminant plume
                                              - Composition of contaminant
                                              - Soil vapor concentrations (optional)
                                                                         Removal rate estimates
                                                                         Vapor flowrate estimates
                                                                         Final residual levels & composition
                                                Air permeability of distinct soil layer
                                                Radius of influence  of vapor wells
                                                Initial vapor concentrations
                                                Drawdown determination
                                                Radius of influence
                                                Pumping  rate determination
                                              - Number of vapor extraction  wells
                                              - Vapor well  construction
                                              - Vapor well  spacing
                                              - Instrumentation
                                              - Vapor treatment system
                                              - Flowrate (vacuum) specifications
                                                                      -  Venting recovery rates
                                                                      -  Changes in vadose zone contamination
    Source: Johnson et al. 1990.
                                                    (Target levels based  on
                                                    exposure  assessment)
Figure 4-3. Guidelines for deciding if SVE is applicable.
                                                         45

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 Chapter 4
 Table 4-3. Characteristics limiting SVE feasibility - contaminant, soil, and site characteristics.
                               Reason for limiting application
                                      Data collection requirements
                                 Application of data
   CONTAMINANTS

   Low volatility (vapor
   pressure)

   High density, high water
   solubility

   SOIL

   Low air permeability


   High humic content
  High moisture content
  Low temperature

  High clay content
  PH
  Low porosity
  SITE

  Distribution and quantity of
  contaminants
  Variable soil
  conditions/characteristics


  Stratigraphy, heterogeneity
  Buried debris
 Indicative of low potential for
 contaminant volatilization
 Contaminant identification
 Tendency to migrate to saturated zone   Contaminant identification
 which is less efficient for SVE
 Hinders movement of air through soil
 matrix

 Inhibits volatilization, high sorption of
 VOCs, need for column test
 verification

 Hinders movement of air through soil
 and is a sink for dissolved VOC's.
 May require consideration of water
 table depression

 Lowers contaminants' vapor  pressures

 Loss of structural support through the
 drying of clay

 Hinders movement of air through soil;
 need for field permeability tests

 Material selection
Hinders movement of air through soil;
need for field air permeability tests
May not be cost effective; will require
overall definition of contamination and
potential NAPL* pools; need pilot-
scale verification

Inconsistent removal rates "short
circuiting" or bypassing contaminated
zones

Affects well design and placement,
and SVE design; need field air
permeability tests and/or pilot-scale
verification

Inconsistent removal rates; need field
air permeability and/or pilot-scale
verification
 Field air permeability test
 Analysis for organic matter
Soil temperature

Shrinkage limit tests
                                                                    Field air permeability, moisture
                                                                    content
Porosity (calculated) specific
gravity, bulk density
Soil mapping, soil gas survey,
site characterization
Soil mapping and
characterization (type, particle
size, porosity)

Field air permeability
(distribution) tests
 Remedy screening


 Remedy screening



 Remedy selection


 Remedy screening
Analysis of soil moisture content    All phases
All phases

Remedy screening


Remedy selection
Remedy design,
remedy selection

All phases
Remedy selection
Remedy screening
                                                                                                    Remedy selection
                                                                   Site history, geophysical testing     Remedy screening
*Non-aquoous phase liquids

Source: U.S. EPA March 1, 1991

   To provide an indication of SVE project costs, three
examples from the case studies cited are presented.
Table 4-6 identifies the costs for the Verona Well Field
Site work in Michigan. These costs indicate the overall
                                 costs for various aspects of the project.  Of interest is
                                 the  comparison of the activated  carbon vapor treat-
                                 ment system, which  was initially  installed,  to the
                                 catalytic oxidation process which later replaced the ac-
                                                           46

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                                                                          Soil Vapor Extraction Technologies
Table 4-4.  Factors affecting SVE treatment costs.
  Component affected
                                  Factors governing component
                                          selection
                                                 Data required
  Number of extraction wells
  Passive wells (inlet) and air
   injection wells

  Depth of wells

  Vacuum pump  or blower


  Vapor/liquid separator


  Surface seals
Radius of influence


Extent of contamination

Air flow distribution


Depth to impermeable layer

Vacuum  level and air flow rate


Liquid (water) removal rates


Air flow distributions
                                Surface water infiltration

  Water table depression pumps     Depth to water table
Pressure profile from air permeability and pilot tests;
mathematical model to optimize selection1

Contaminant distribution

Air permeability tests; pilot tests, number of vapor
extraction wells

Depth to bedrock2; depth to water table

Air permeability tests, pilot tests, number of vapor
extraction wells

Moisture content, vapor flow rates (oversized mist
eliminator recommended)

Air permeability tests, pilot tests, mathematical modeling
of air flow patterns

Rainfall, permeability for surface soils

Depth to water table
  Off-gas treatment
  Liquid (water) treatment
  Operating costs
Water infiltration rates

Contaminant removal rates,
contaminant identities, moisture
content after vapor/liquid
separation

Site water removal rates
Size of SVE system, cleanup time,
analytical costs, and residuals
disposal  costs
Site hydrological behavior

Air permeability tests, pilot tests; moisture content
during pilot tests
Site hydrological behavior, moisture content in off-gas,
contaminant concentrations in water

All of the above plus cleanup time predictions based
upon mathematical modeling and prior experience
 1ln general, specify more wells than predicted by the mathematical model
 location and subsurface conditions.
 20n some sites, SVE may be the only available technology for application
 than wells bored into soils.


 Source: U.S. EPA March 1,  1991
                              as optimum because of uncertainties in the contaminant

                              to fractured bedrock. These wells will be much more costly
tivated carbon system for vapor treatment (McCann
1990).
   Construction and operating cost summaries for the
TCAAP case study  (Site D  and G) are presented  in
Tables 4-7 and 4-8,  respectively.  Remediation of Site
D soils have  been estimated  at US$451,000 or
US$22/m3 (US$17/yd3) soil.  Air emission controls
were not required for the Site  D system.  Site G soils
have been treated at an estimated cost of US$969,000
or US$17/m3 (US$13/yd3) soil.
   To provide general assistance in developing a
rough SVE cost estimate, Table 4-9 presents capital,
and operating and maintenance costs for each of the
SVE system components over typical operating  size
ranges.  Capital and certain operating costs  may be
                           approximated by determining the system size and mul-
                           tiplying unit size estimates by the values given in the
                           table  (U.S. EPA 1991a).  It also presents costs for
                           polyvinyl chloride (PVC) and stainless steel (SS)
                           materials of construction for extraction well construc-
                           tion.  The compatibility of the contaminant and other
                           soil chemical  characteristics with the well and piping
                           materials needs to be assessed before system  con-
                           struction. For example, stainless steel will not perform
                           well under very corrosive or high chloride conditions.
                           Similarly, PVC may be  attacked by certain organic
                           compounds.   The surest way to establish the ap-
                           propriate  materials of construction is to consult  ven-
                           dors  of  these  products.   It should be  noted that
                           vapor/liquid separators have been included as an in-
                                                       47

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 Chapter 4
 Table 4-5. Terra Vac economic model (in US$, 1989).


  Cost components	  $/tonnes

  Sito preparation                               3.12

  Permitting and regulatory

  Equipment
   Contingency (10% of direct costs)                .31

  Startup and fixed cost
   Operations procedures/training                   .44
   Mobilization and shakedown                     .92
   Depreciation (10% of direct costs)                .31
   Insurance and taxes (10% of direct costs)           .31

  Labor costs                                  3.05

  Supplies - Raw materials

  Supplies - Utilities
   Electricity                                    .44

  Effluent treatment                            14.14

  Residual disposal                              8.27

  Analytical
   During operation                             1.59
   Protest and posttest analyses                   18.36

  Facility modifications
   (10% of direct costs)                           .31

  Sito demobilization                              .36

   TOTAL  	                       51.93


 •Based on equipment capital cost of $50,000 for treating
  approximately 5,440 tonnes of contaminated soil. Does
  not Include profit for the contractor.

Source: U.S. EPA July 1989
Table 4-6. Verona Well Field SVE costs (in US$, 1990).

  COST COMPONENTS
   Design of pilot-scale unit, full-scale
   construction, and startup
$500,000
   Carbon adsorption system and total cost   $610,000
   of carbon

   Catolytio oxidation system              $187,000

   Operations including utilities, process      $305,000
   monitoring and maintenance

 UNIT COSTS

   Cleanup of contaminated soil            $30/m3

   Cleanup of contaminants	$79/kg

Source: Personal communication
 tegral part of the SVE system.  However, vapor treat-
 ment processes which are dependent on the con-
 taminants and concentrations are not included.

 4.8   Future Status of Case Study
       Processes and the SVE Technology
       as a Whole
    At the Dayton site and the  two sites in the Twin
 Cities  Army Ammunitions  Plant  case study, SVE
 remediation has been completed; at the Verona Wells,
 Hill AFB and  the Groveland sites, remediation con-
 tinues.
    Future technology applications seems  highly
 promising as  the process has several advantages.
 Soil vapor extraction can be effectively used for remov-
 ing a wide range of volatile  chemicals under a wide
 range of conditions.  The process can be part of a
 remediation effort and used along with other treatment
 processes.  Air injection has the advantage of control-
 ling air movement, but injection systems need to be
 carefully designed.  Volatile chemicals can be ex-
 tracted from clays and silts but at a slower rate. Inter-
 mittent operation  is more efficient under  these
 conditions.   The intermittent  blower operation  is
 probably more efficient in terms of removing the most
 chemical with the least energy. The design and opera-
 tion of these systems can be flexible enough to allow
 for rapid changes in operation, thus, optimizing the
 removal of chemicals. Equipment used for  SVE sys-
 tems is readily available and easy  to operate.  To
 protect down stream air pollution control equipment,
 air/water separators should  probably be installed  in
 every system.  Such  devices are inexpensive and easy
 to construct.
    As with any in situ process, it is usually impossible
 to do a complete materials balance on a given site be-
 cause most sites have an unknown amount  of VOC's
 in the soil and in the ground water.  As a result, it  is
 difficult to establish when the cleanup has been com-
 pleted.  To determine if contaminants are continuing to
 vaporize, SVE processes could be operated  on an in-
 termittent basis for a period of time after the VOC con-
 centrations in the extracted vapors have approached
 zero. This technique can  help to limit the soil boring
 and ground water data on residual contamination re-
 quired to demonstrate that cleanup objectives have
 been attained. Although  many  aspects of  the SVE
technology are understood, additional information
which would be of assistance to engineers and opera-
tions  personnel needs to be developed.  Documenta-
tion of case studies where difficulties resulting from the
misapplication of the technology or operating  problems
would be useful. All too often, only success stories are
documented.   However, failures or marginal succes-
ses can provide more insights into factors which need
to be considered in other applications. These can be
particularly useful when a thorough investigation/ as-
                                                   48

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                                                                       Soil Vapor Extraction Technologies
Table 4-7. TCAAP Site D — Estimated
Description
CAPITAL
System installation
Subtotal
OPERATIONS AND MAINTENANCE2
Labor3
Professional labor
Craft labor
Subtotal
Operations
Electricity
System monitoring
Subtotal
TOTAL
construction and operating costs (in US$).
Units Cost/Unit ($) Cost ($)
257,000
1000 hours 50/h 50,000
1 500 hours 30/h 45,000
1 ,770,000 kWh 0.04/kWh 71,000
160 samples 175/sample 28,000


Total ($)
257,000
95,000
99,000
451,000
 'Cost information supplied by TCAAP (U.S. EPA July 1990). Does not include design, construction supervision, vent sampling,
 or safety monitoring.
 2Total over operating period (February 86-May 90).
 Estimated as 70 percent of Site G information (see Table 4-8).
sessment of the failure identifies the cause(s) of that
failure.
   It is known that temperature affects the volatility of
organic compounds and therefore the efficiency of the
SVE process.  Under what conditions and for what
contaminants would  it be cost effective to consider
technologies such as RF heating to increase the soil
temperature in order to extract organic contaminants
or speed remediation?   Would  heated air injection
serve the same purpose, and what effect would it have
on  extraction rates?  How would implementation of
such techniques change  the  overall efficiency of the
process for different soil types?
Table 4-8. TCAAP Site G — Estimated construction and operating costs (in US$).
Description
CAPITAL
System installation
Vapor treatment system
Subtotal
OPERATIONS AND MAINTENANCE2
Labor
Professional Labor
Craft labor
Subtotal
Operations
Electricity
System monitoring
Carbon changeouts
Subtotal
TOTAL
Units Cost/Unit (ง)

1400 hours 50/h
2200 hours 30/h
2,400,000 kWh 0.04/kWh
180 samples 210/sample
16 changes 14,300/change

Cost (ง)
257,000
213,000
70,000
66,000
96,000
38,000
229,000

Total ($)
, 470,000
136,000
363,000
969,000
 'Cost information supplied by TCAAP (U.S. EPA July 1990). Does not include design, construction supervision, vent sampling,
 or safety monitoring. .     ,     '.                                            ....           ,   .,   	
 2Total over operating period (February 86-May 90).
                                                     49

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 Chapter 4	

 Table 4-9.  Capital cost estimation of SVE components (in US$, 1990).
                                                                           Capital
           Component
PVC1
                    304 SS2
                                                                                        Other
           Extraction Well Construction

            Drilling

            Casing
             5cm                            $7-$10/m
             10cm                           $10-$16/m
             15cm                           $23-$29/m

            Screen
             5cm                            $7-$13/m
             10cm                           $16-$23/m
             15cm                           $33-$49/m

            Sand or gravel

          Piping
             5 cm                            $3-$7/m
             10cm                           $7-$13/m
             15cm                           $20-$33/m
             20 cm                           $39-$527m

          Valves (ball)
             5 cm                            $60
             10cm                           $150
             15cm                           $700
             20cm                           $1,300

          Joints (elbow)
             5 cm                            $11
             10cm                            $50
             15cm                            $100
             20 cm                            $460

          Water table depression pumps (45-95
          gpm)

          Surface seals
           Bontonite
           Polyethylene (.254 mm)
           HOPE
           Asphalt

          Blower (rotary or ring)
           0-28 dNnvVmin
           8-14dNm3/min
           28 dNnvVmin

          Vapor/liquid separators
           (3,800 L to 7,600 U

          Instrumentation
           Vacuum gauge
           Flow (Annubar)
           Sampling port
           Gas  chromatograph/FID
                                  $2,000 to $5,000/well
                  $39-$46/m
                  $75-$82/m
                  $118-$131/m


                  $49-$56/m
                  $89-$102/m
                  $134-$151/m
                  $31-$36/m
                  $72-$82/m
                  $111-$125/m
                  $171-$180/m
                  $1,000
                  $2,000-$2,200
                  $3,200
                  $5,000
                  $20
                  $52
                  $300
                  $560
                                  $20-46/m3
                                  $3,700


                                  $99/m2
                                  $2.70/m2
                                  $6/m2
                                  $6/m2
                                  $5,000 to $25,000
                                  $13,000
                                  $40,000

                                  $3,500 to $17,500
                                 $50-$75
                                 $300
                                 $20-$30
                                 $20,000 (if purchased;
                                  usually rented)
'Polyvinyl chloride
'Stainless stool

Source:  U.S. EPA March 1, 1991
                                                      50

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                                                                  Soil Vapor Extraction Technologies
   At this time, SVE systems are often designed with
flexibility so that changes can be made  during
remediation.  Although  such system flexibility is
desirable, it also can increase costs. Since there have
been numerous installations of the SVE system under
a wide range of site, soil and contaminant conditions; it
appears that an analysis  of these applications could
provide useful information to design engineers as well
as operating personnel.   Johnson et al. (1990) have
supplied a beginning for the development of such
guidelines.  This needs to be expanded to reflect "les-
sons learned" from SVE  applications.  For example,
operating criteria  need to  be established outlining
those conditions when a system should be operated in
the  intermittent  extraction mode rather than a con-
tinuous extraction mode.
   Little attention has been paid to the effect  of
naturally occurring organics on extraction rates or the
ultimate removal efficiencies.  Since such soil com-
ponents can adsorb organic contaminants, to what ex-
tent do they reduce the effectiveness of the process?
   It has been found that SVE can be used to enhance
in situ biodegradation of a number of nonhalogenated
VOC's and other semivolatile compounds in subsur-
face soil.  Similar information is needed for a wider
range of organics and site conditions. And more work
is needed  to examine SVE and bioremediation as a
process rather than looking at each technology  in-
dividually.
    Since buildings and  other interferences can  be
found at many sites where VOC contamination occurs,
 it is likely that it will be necessary to remediate con-
taminated  soils  near these structures.  What special
 techniques (e.g.,  horizontal drilling) could be used
 under these conditions?  Would using SVE  result  in
 transporting vapors into the building or could they  be
vented away?   Additionally, at the Dayton, Ohio fire
site, it was found that VOC vapor could be transported
through concrete.  Is asphalt similarly affected? The
answers to these questions would be useful in deter-
mining what cap configurations and construction
materials should be used.
   Other technical issues that need to be resolved in-
clude the effectiveness of forced or passive vapor in-
jection wells; other means of controlling vapor flow
paths; well-documented demonstrations for removing
contaminants from low-permeability soils; the pos-
sibility of decreasing  residual contaminant levels in
water-saturated zones by air sparging/vapor extrac-
tion; and optimal operation schemes for multiple vapor
extraction well systems (U.S. EPA 1991a).
    Alternative treatment  methods for off-gasses
provides an other area for future investigations.  For
example, an Advanced Oxidation Process is being
studied for the destruction of VOC's in air; this work is
being conducted at the Lawrence Livermore National
Laboratory under U.S.  EPA Superfund Innovative
Technology Evaluation (SITE) program. The destruc-
tion mechanism is based on photolytic oxidation of
contaminants using a newly developed ultraviolet (UV)
 light source, consisting of a pulsed-plasma xenon
flashlamp that generates extremely intense UV emis-
 sions.  These UV emissions are better suited for or-
 ganic contaminant destruction  than  conventional
 mercury-based UV lamps because the  photon flux is
 shorter in wavelength and higher in intensity.  Prelimi-
 nary experimental results indicate that the proposed
 UV flashlamp treatment scheme will yield high VOC
 destruction rates.  This process can be coupled to the
 gas venting system and creates no secondary waste
 stream.
 REFERENCES
      Camp  Dresser andMcKee, Inc. Interim report for field evaluation of Terra Vac corrective action technology
      at a Florida LUST site. Contract No. 68-03-3409, U.S. Environmental Protection Agency.  Edison, New
      Jersey, December 21,1987.
      Danko J P  McCann M.J. and Byers, W.D. Soil vapor extraction at a Superfund site in Michigan. Presenta-
      tion at U.S. Environmental Protection Agency SITE Conference in Philadelphia, Pennsylvania, May
      1990.
      Downey, D.C., and Elliott, M.G. Performance of selected in situ soil decontamination technologies: An Air
      Force perspective. Environmental Progress (Vol. 9, No. 3), August 1990.

      Hutzler, N.J., Murphy, B.E., and Gierke, J.S. State of technology review.  Soil vapor extraction systems.
      Department of Civil Engineering, Michigan Technological University, Houghton, Michigan. U.b. tn-
      vironmental Protection Agency, Cincinnati, Ohio, August 1988.

      Johnson P C  Stanley, C.C., Kemblowski, M.W., Byers, D.L., and Colthart, J.D.  A practical approach to the
      design, operation, and monitoring of in situ soil-venting systems.  Groundwater Monitoring Review,
      Spring 1990.

      McCann, M., CHaM Hill. Personal communication. October 26, 1990.
                                                   51

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Chapter 4
                 ^rPhase destruction of organic contaminants in groundwater and soil using advanced




                                                           contaminated soil' TAUW lnfra Cฐ™"' B.V.,
    Terra Vac, Inc. Demonstration test plan: In situ vacuum extraction technology, SITE Program, Groveland
    Wells Superfund Site, Groveland, MA. Enviresponse No. 3-70-06340098, US Environmental Protec
    tion Agency, Cincinnati, Ohio, November 1987.

             < Tฃchno!ฐ9y evaluation report: SITE program demonstration test Terra Vac in situ vacuum extrac-
                                       Vฐ'Ume '• EPA/540/5^-003a, U. S. Environments Protection
    U.S. EPA. Applications analysis report:  Terra Vac In situ vacuum extraction system, EPA/540/A5-89/003
    U.S. Environmental Protection Agency, Cincinnati, OH, July 1989.

    Pi'S n?LA> 50ilva50r5xtlia(2io^s VOC control techno|ogy assessment, 450/4-89-017, Office of Air Quality
    1989        Standards, U.S. Environmental Protection Agency, Durham, North Carolina, September
        ,' yacuumAextraction ซeld demonstrations - draft report.  Roy F. Weston, Inc. for the U.S. Environ-
    mental Protection Agency, Cincinnati, Ohio, July 1990.
     ™-                   lntemattona' Conference: Demonstration of remedial action technologies
    tor contaminated land and ground water. Angers, France, November 1 990.

    U.S. EPA. Soil vapor extraction technology: Reference handbook. EPA/540/2-91/003, Risk Reduction En-
    gineering Laboratory, Cincinnati, Ohio, February 1991 .
    P™,         K fฐ,r condu?ting treatability studies under CERCLA:  Soil vapor extraction. Risk Reduction
    Engineering Laboratory, Office of Emergency Remedial Response and Office of Solid Waste and Emer-
    gency Response. Revised Final Draft March 1 , 1991
                                              52

-------
Physical/Chemical Extraction Technologies

Merten Hinsenveld
University of Cincinnati, Department of Civil and Environmental Engineering
741 Baldwin Hall (ML 71), Cincinnati, Ohio 45221-0071
United States
ABSTRACT
   Six case studies, covering a broad spectrum of techniques, were chosen for this t>4ATO/CCMS Pilot Study: ex
situ extraction (two case studies); In situ acid extraction (one case study); in situ jet cutting followed by oxidation
(one case study); electro-reclamation (one case study); and debris washing (one case study).
   The  ex situ extraction techniques (Kiockner and Harbauer)  mainly differ in  scrubber technology and the
combination of particle separation techniques. The two techniques clean the soil mainly through removal of the heavi y
contaminated fines from the soil. Their best result is generally obtained for sandy soils. Both techniques are available
on a commercial scale.
   The  applicability of in situ extraction techniques in general, where removal of the heavily contaminated fine
particles is not possible, is limited to sandy soils. The In situ acid extraction technique (TAUW/Mourik) is applicable
for sand only The site contained cadmium pollution and was ideally suited forthe technique (sandy soil, low adsorptive
capacity, homogeneous). The cleaning results were better than expected; the results are considered an ideal case.
The technique is available on a full scale.
   The  in situ jet cutting technique (Keller) is capable  of removing contaminated soil with  the simultaneous
replacement of clean stabilized soil. This makes the technique in principle applicable for cleanup activities underneath
buildings. The oxidation was applied on the easily oxidizable contaminants (e.g., phenols) in the removed son. i ne
technique is available on a pilot scale.
   In situ electro-reclamation (Geokinetics) is a new technique for heavy metals removal. Whereas the other
techniques are applicable to sandy soils, electro-reclamation can be applied to clean clayey soils contaminated with
heavy metals At present no other technique exists for heavy metals removal from clayey soils. The technique uses
the flow of water which is  induced by applying an electrical field to the soil, but the removal mechanism is not yet
fully understood. A full-scale system is operable. Promising results have  been obtained with cleanup of soil and
sludge contaminated with copper, zinc, lead, and arsenic.
 5.1  Introduction

 5.1.1 Place of the Techniques in a Broad Sense
    This chapter concentrates on ex situ and in situ ex-
 traction, in situ jet cutting followed by oxidation, and in
 situ electro-reclamation. These techniques were sub-
 mitted as case studies to the NATO/CCMS Pilot Study.
    The case study techniques belong to a group
 generally referred to as physical-chemical treatment
techniques. They aim at removal or destruction of con-
taminants and are generally executed in an aqueous
environment. Examples of other techniques in this
group are: particle  separation techniques, flotation
techniques, and  reduction and dechlorination techni-
ques.
   Ex situ extraction, as presently applied in soil clean-
ing, mainly refers to a combination of particle separa-
tion techniques and dissolution and dispersion in an

-------
  Chapter 5
  aqueous environment.  This chapter only deals with
  aqueous extraction agents.  The use of organic sol-
  vents to, for instance, extract PCB's from soils and
  sediments, is in development and approaching com-
  mercial scale.  When organic solvents are used, the
  technique is referred to as solvent extraction. Solvent
  extraction is not discussed in this section.
     The term "extraction" was adopted in the early
  stages of development, beginning in the 1980's, be-
  cause it was believed that contaminants could easily
  be extracted from the soil. At present we know that,
  because contaminants are heavily adsorbed onto the
  fines (particles smaller than 63 m), the cleaning in
  these installations is mainly due to the separation of
  these heavily contaminated fines from the bulk of the
  soil.  Therefore the term "classification" techniques
  would have been more appropriate.
     In situ extraction has been applied to a limited ex-
  tent, because separation of heavily contaminated fines
  is not possible. It is, therefore, limited to those  cases
  where the soil does not contain  adsorptive materials.
  The case study described in this chapter is an example
  of such an ideal site.
     In situ jet cutting followed by oxidation is a  rather
  unique case study  in that the soil is removed  by jet
  cutting as opposed to being excavated, and backfilled
  after  treatment. In  the case study described  in this
 chapter,  no particle separation techniques were ap-
 plied. The easily oxidizable contaminants were ideal
 for applying this technique. It may, therefore, be con-
 sidered a best case  example.
    Electro-reclamation  has very recently been  intro-
 duced in the field of soil treatment. Little experience
 with this technique has been gained so far. The techni-
 que applies  an electrical field to the soil.  It  either
 creates an electrical driving force for the contaminants
 themselves, called electro-phoresis, or it induces  water
 flow, called electro-osmosis, in which dissolved con-
 taminants may be entrained. This technique is  espe-
 cially suitable for removal of heavy metals from clayey
 soils.  There are presently no other techniques  avail-
 able for these "difficult" soils.

 5.1.2  Principle of Extraction Techniques
    The basic processes in extraction installations con-
 sist of (1) pre-screening of the soil, (2) mixing with an
 extracting agent, (3) fluid-solids separation, (4) treat-
 ment of the cleaned soil, and (5) water purification and
 sludge treatment. (See  Figure 5-1.)
    Extraction installations may incorporate a variety of
other techniques besides the actual extraction. In
general, particle separation techniques (separation on
size and/or density), chemical treatment (mainly oxida-
tion), and flotation techniques are integral components
of extraction installations. In principle the same
process scheme will  be applied for the oxidation tech-
nique,  but  without significant separation of  the  fines
                Contaminated soil

                      I
                  Pretreatment
                     I
                                  Coarse material
       Water


    Chemicals
Scrubbing and
  extraction
                                Extracting
                                agent —ซ
                    Phase
                   separation
                After-treatment
                   Cleaning of
                 extracting agent
                                        I
                                      Sludge
                 Cleaned soil
                               Sourco: Hlmonvold 1990.
 Figure 5-1. The basic processes in extraction installa-
           tions.

 and with the water purification step consisting of oxida-
 tion only.
    Flotation techniques in the present extraction instal-
 lations are only used to clean the process water, but
 they may also be used to clean soil. This latter applica-
 tion, however, requires special knowledge, so that only
 a few firms have specialized in this (very powerful)
 technique. Most firms using extractive methods do not
 have the required knowledge for this application. Flota-
 tion as a soil cleaning technique is available on full
 scale in The Netherlands, but is not referred to in this
 chapter.
    Most of the cleaning efficiency in extraction installa-
 tions, in general, is  from the removal (separation) of
 the heavily contaminated  fines from the  soil.  The
 chemicals added in  the  scrubber, mostly NaOH  and
 some  soaps, mainly serve  as dispersing agents to
 keep these fine particles  in suspension.
    The  process  of extraction-classification  can
 economically be applied to soils with a combined fines
 and organic matter content of less than about 30 per-
 cent. There is a simple reason for this limitation: fines
 are difficult to dewater and  lead to huge amounts of
 sludge. For example: one tonne of  soil containing 30
 percent fines leads to about 0.6 tonne of contaminated
 sludge (compared to  the original soil, the water content
 of the fines is roughly doubled) and 0.7 tonne of clean
 soil; the waste  stream  has been reduced by only 40
 percent.  In exceptional cases, the contaminants con-
tained in the fines may be destroyed  by oxidation or
other techniques. In that case there  is  no limitation on
the amount of fines.  In general, however, part of  the
fines will consist of organic matter, and removal of the
                                                   54

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                                                            Physical/Chemical Extraction Technologies
fines prior to oxidative treatment will largely reduce the
amount of oxidants to be used for destruction of the
contaminants.
   It will be clear from the above that the applicability
of in situ extraction techniques is quite limited because
removal of heavily contaminated fine particles is often
not possible.

5.1.3  Principle of Electro-reclamation
   Electro-reclamation is a rather new technique for
heavy metals removal from soils in situ. The principle
of the movement of water, charged particles, and ions
in a saturated porous medium when subjected to an
electrical field is well known.  The principles of
electrophoresis and  electrolysis are widely used in
analytical measurements; the movement of water is
utilized  in practice and includes dewatering and con-
solidation  of soils  in foundation engineering
(Casagrande  1983). The  technique has also been
used  for desalting agricultural land.  The possibilities
and limitations in environmental applications, however,
are still a subject of research.
   Researchers do not  quite agree on  whether the
primary removal mechanism for the heavy metals from
soil is electro-osmosis, electrophoresis, electrolysis, or
a combination of mechanisms. The removal efficiency
can possibly be improved by using acoustic waves in
addition to the electrical field  - a technique known to
enhance dewatering  of sludges or leaching of waste
(U.S. EPA 1990) - or by the addition of acid (Lageman
et al. 1990).  Oxidation and reduction reactions in-
duced by the electrical field are also a subject of study.
   Electrochemical studies have shown that an acid
front is generated at the  anode,  migrating in time from
the anode towards the cathode (U.S.  EPA 1990).
Metallic electrodes as well as  metallic objects (e.g.,
drums and  pipes) in the soil will either corrode and
thus interfere with the removal of  heavy metals or be
coated with  metals. Therefore, graphite electrodes are
often used in the  field and metallic objects should be
removed prior to treatment.
   In general the flow of  water will be directed from the
anode to the cathode due to the net positive charge of
the solute. Depending on this charge, the complexes
will either move to the cathode or to the anode. Water
flowing towards the cathode  is  pumped off, together
with the dissolved ions. A solution of  HCI or NaCI is
infiltrated at the anode to  replace the removed ions,
preventing  an equilibrium from  establishing.  Promis-
ing results have been obtained when cleaning up soils
and sludges contaminated with  heavy metals like Cu,
Zn, Pb, and As. In principle, the technique is applicable
for most types of soil, but  is particularly applicable to
cleaning clayey soils. For  cleaning very permeable
and sandy soils, a conventional in  situ extraction might
be cheaper. The technique also  shows possibilities for
cleaning soils and sludges in storage facilities.
5.2   Case Studies Chosen
   The five case studies chosen for this pilot study
cover a broad spectrum of techniques:
   • Ex situ extraction (two case studies)
   • Oxidation (one case study)
   • In situ extraction (one; case study)
   • Electro-reclamation (one case study).

   In this section, a brief description of each of the
case studies will be given.

5.2.1 Case Study 5-A: High Pressure Soil Washing
      (Klockner), Germany
   The  high pressure soil washing  system was
developed in  The Netherlands by BSN  in the middle
1980's and adapted by KIScknerto German specifica-
tions. The installation has a commercial scale of about
13 to 36 tonne/h. A description is given in Appendix
5-A. The most characteristic aspect of the process is
the use of a high pressure water jet to scrub the soil
particles. Nozzle pressures of  up to 350 bar can be
applied. Pretreatment of the soil is purely mechanical,
consisting of sieving the rubble fraction (lumps greater
than 6 cm) on a coarse screen. The fraction smaller
than 6 cm is fed to the high pressure water jet in which
the  aggregated particles are disintegrated. The
process was selected in the NATO/CCMS Pilot Study
for a number of reasons.  Firstly,  because of its
simplicity: pretreatment is simple and no chemicals are
added. Secondly, because of its large scale and the
experience built  up  over the past 5  years. Up to the
present,  some 300,000 tonnnes of contaminated soil
have been treated with this and the following installa-
tion. The installation can be purchased and is fully
commercial. Thirdly, the process can be used to treat
soils contaminated  with a combination of volatile or-
ganic contaminants  (which are stripped out of the soil
by the air entrained  in the water jet) and heavy metals.
Volatile components are not removed in extraction in-
stallations that do not apply high pressure.

5.2.2 Case Study 5-B: Vibration (Harbauer),
      Germany
   This case  study,  reported in Appendix 5-B, involves
the cleaning  of soils contaminated with oil residuals.
The primary characteristic of this process is the use of
a mechanical vibration scrubbing system. The case
study was chosen for a number of reasons; the most
important was its claim of being able to clean the soil
down to a particle size of 0.015 mm (usually conven-
tional extraction  installations can go down to about
0.050 mm). This low cut off size leads to a  strong
reduction in the amount of sludge produced. The ven-
dor  claims that the exceptionally low particle size of
0.015 mm can be reached by a combination of a wide
                                                  55

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  Chapters  	

  variety of particle separation techniques. The installa-
  tion has a commercial scale.

  5.2.3 Case Study 5-C: Jet Cutting Followed by
       Oxidation (Keller), Germany
    This case study describes the oxidation of soil con-
  taminated with phenols and cresols. The soil is
  removed from the underground by a cutting water jet
  and simultaneously replaced by clean soil. The actual
  cleaning  is done ex situ. Originally the technique was
  used for stabilizing the underground for foundation pur-
  poses, but it has been adapted for treating con-
 taminated soils. The contaminated soil that is  brought
  up by the water jet could be cleaned  by a number of
 wet techniques, but the company involved has no  ex-
 perience  in doing so and chose to use a simple oxida-
 tion technique. The study was selected  for the
 NATO/CCMS Pilot Study because of the possibility of
 applying a wet cleaning technique for soils underneath
 buildings  without the  need of tearing  these buildings
 down. In this respect it could be classified as an in situ
 technique. The technique is also interesting because,
 by using only an oxidation technique without any
 separation techniques, no sludge is produced.

 5.2.4 Case Study 5-D: Electro-reclamation
      (Geoklnetlcs), The Netherlands
   This case study describes the use  of an electrical
 field to remove heavy metals from clay soils. The study
 is reported in Appendix 5-D, including  an excellent
 description of the principle of the  technique. The site
 studied in this case was contaminated with  arsenic
 caused by a former timber preservation  impregnating
 plant. Field experiments have been conducted  by a
 number of researchers, but problems at the electrodes
 occurred. Geokinetics claims to  have mastered this
 problem. The case study was chosen because of the
 application of this new technique which can be applied
 In situ to  remediate clayey soils contaminated with
 heavy metals.  For these soils, no alternative  techni-
 que is presently available.

 5.2.5 Case Study 5-E: In Situ Acid Extraction
      (TAUW/Mourik), The Netherlands
   This case study, the results of which are described
 in Appendix 5-E, deals with the in situ cleaning of a
 sandy soil contaminated with cadmium. The cadmium
 contamination, caused by a photographic paper fac-
tory, was  bleached into the soil in a liquid form.  This
case study was chosen because the problem studied
here represents  a best case for in situ extraction: a
very mobile contaminant in a permeable soil  having
low adsorptive capacity.

5.2.6  Case Study 5-F: Debris Washing, United
      States
    This technology applies to the decontamination of
 metallic debris, such as transformer casings, drums,
 and miscellaneous scrap metal which is often found at
 hazardous waste sites.  Because the rest of this chap-
 ter discusses technologies for  the cleaning of  soil,
 greater detail about debris washing will not be included
 in this chapter. However, considerable detail on debris
 washing can be found in Appendix 5-F.

 5.3   Background of the Case Study Sites
       as a Group
    Table 5-1  shows an  overview of the different case
 study sites. It can be  concluded that there is  little
 resemblance  between these  sites, showing the wide
 range of application of physical  chemical techniques.
 As can be expected, however, most sites applying ex-
 traction contain sandy soils, leading to an acceptable
 amount of sludge produced. Acceptable may be
 defined to mean that cleanup costs plus the cost of
 sludge disposal are less than or  equal to the disposal
 of the contaminated soil. For the Klfickner installation
 (Case Study 5-A), the fraction smaller than 0.063  mm
 ends up in the sludge, whereas for the Harbauer sys-
 tem (Case Study 5-B) only the  fraction  smaller than
 0.015 mm becomes sludge. The site on  which in situ
 extraction was applied (Case Study 5-E) was extreme-
 ly sandy and is an exceptional site. The electro-
 reclamation study (Case Study  5-D) involved clayey
 soils. This technique is exceptional in a sense that it is
 the only technique capable of cleaning these difficult
 soils.
    In the in situ acid extraction (Case Study 5-E), there
 were  no fines and no organics at all present in the soil.
 The amount of organics in the  jet cutting  oxidation
 case study (Case Study 5-C) did not seem to influence
 the performance of the  oxidation process.  The case
 study on electro-reclamation and the in  situ acid  ex-
 traction case study can  be regarded as  opposites in
 that electro-reclamation works with clay soils having a
 low permeability, whereas  in situ acid extraction only
 works when the soils are very sandy and  show a high
 permeability. If soil is very permeable and has a  low
 adsorptive capacity, extraction is cheaper than electro-
 reclamation. Electro-reclamation is needed in case  the
 soil is very impermeable.

 5.4   Performance Results
   In  extraction, cleaning results  strongly depend on
the form in which contaminants are present  in the soil
 and the grain  size distribution, Generally difficult to
clean  are soils containing a large fraction of particles
smaller then 0.060 mm or soils containing a large
amount of organic  material. In  ex situ extraction,  the
fines end up in the sludge.  A small fraction  of highly
adsorptive particles in the soil make the ex situ extracr
tion easier, because separating this fraction from the
soil removes most of the contaminants as well.
                                                 56

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                                                           Physical/Chemical Extraction Technologies
Table 5-1. Problems handled in the NATO/CCMS case studies.
Process/
Technique
Manufacturer

Country
City
Area (m2)
Depth (m)
Source of
contamination

Type of soil

Type and
concentration of
contaminants


Amount of soil to be
treated (tons)
Main lesson learned





High pressure soil
washing
Klockner

Germany
Berlin
unknown
unknown
Scrap metal, copper
refinery

Sandy soil, less than
20% clay
Heavy metals,
halogenated
hydrocarbons, non-
halogenated
hydrocarbons
100,000

	





Vibration

Harbauer

Germany
Berlin
1 6,000
unknown
Oil recovery


Sandy soil

Halogenated
hydrocarbons.
aromatics, oil


unknown

—





Jet cutting/
oxidation
Keller

Germany
Hamburg
unknown
unknown
Disinfectant
factory

Sand, clay and
peat
Phenols, cresols




unknown

-





Electro-
reclamation
Geokinetics

The Netherlands
Lopperisum
unknown
1-2
Timber
impregnating
plant
Clay

Arsenic 400-500
mg/kg



450

Presence of
metal objects
can have a large
influence on
cleaning results

In-situ acid
extraction
TAUW/
Mourik
The Netherlands
Soestduinen
6,000
unknown
Photographic
paper factory

Sandy soil

Cadmium




45,000

Adsorptive
capacity and
permeability as
measured in
laboratory differs
from practice
   A major difficulty  encountered in interpreting the
results of the case studies was the absence of inde-
pendently obtained data. Data available from the com-
mercial vendors involved generally represent their best
results (mostly in sandy soils).  Presenting cleaning
results of sandy soils generally leads to higher clean-
ing efficiencies than would be obtained on the average
in practice.  In the jet cutting oxidation case study
(Keller, Case Study 5-C), only easily oxidizable con-
taminants were present.
   The electro-reclamation case study has a some-
what different position in that the technique is used for
soils that are difficult or impossible to clean with other
techniques.
   High pressure soil washing (Case Study 5-A,
Kldckner). The case study  of Klockner,  shows dif-
ferences obtained in  cleaning efficiency ranging from
35 to 100 percent. These  differences cannot be ex-
plained, due to insufficient information provided by the
vendor. The soil treated  by Klockner is an easily
cleanable sandy soil containing about 1.6 percent par-
ticles smaller than 0.063 mm.
   Vibration (Case Study 5-B, Harbauer). The soil
cleaned with the Harbauer system contains more fines
than the soil treated in the Klockner case (37 percent
smaller than 0.1 mm) and is probably more difficult to
clean without getting a large amount of sludge. How-
ever, Harbauer claims to produce a residue of only 2
percent, meaning that most of the fines above 0.015
mm were not heavily contaminated  or could be
cleaned and subsequently separated. We have been
unable to check these claims. The cleaning efficiency
for mineral oil, PAH's,  phenol,  and cyanide ranged
from 86 to 100 percent.
   Water Jet followed by oxidation (Case Study 5-
C, Keller). In contrast to the two extraction techniques
(Klockner and Harbauer), no particle separation tech-
niques were used in this  project. The results show a
destruction  efficiency of more  than 90 percent for
phenol. Reaction time needed ranged from 0.5 h to 3
h, mainly depending on the degree of destruction and
the amount of organic material in the soil.
   Electro-reclamation (Case Study  5-D,
Geokinetics). The Geokinetics case study shows that
removal of arsenic from a clay soil is possible, bringing
concentrations down from more than 250 ppm to about
100 ppm and lower. In particular, one part of the site
was difficult to clean, due to the presence of metal ob-
jects that functioned as preferential conductors for the
                                                 57

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 Chapters	

 electrical current, thereby delaying the movement of
 the contaminants in their vicinity.
    An important lesson learned from this experience is
 the need to identify metal objects  in the soil and
 remove them before electro-reclamation is applied.
    In situ acid extraction  (Case Study 5-E,
 TAUW/Mourlk). The TAUW/Mourik case study can be
 regarded as an example of an in situ acid extraction
 under ideal conditions. The soil cleaned is very perme-
 able and contains hardly any adsorbing material. The
 results of a trial were so good that the initial cleaning
 goal was brought down from 5 mg-Cd/kg to 2.5 mg-
 Cd/kg. It was found that the desorption of cadmium in
 practice was better than was expected on the basis of
 laboratory studies. The permeability of the deeper
 layers of soil was found to be quite different from the
 permeability of the top soil.

 5.5   Management of Residuals
    In  ex situ extraction techniques the main cleaning
 mechanism, in general, is the separation of the fines
 from the soil. In most cases, fines are the fraction of
 particles smaller than about 0.063 to 0.030 mm  (an
 exact definition of 'lines" is not useful). Separating this
 fraction from the soil leads to the production of sludge,
 which is generally the  main drawback of  extractive
 methods. Sludge consisting mainly of fines is con-
 sidered non-cleanable and is disposed of in a control-
 led dump site. Harbauer is the only vendor that claims
 to be able to clean the fraction between 0.050 mm and
 0.015 mm, therefore producing only limited amounts of
 sludge. However, past experience in The Netherlands
 has shown that it is doubtful that this will hold true in
 general. In the  relatively  few cases where the con-
 taminants are not heavily adsorbed to the fine fraction,
 the contaminants entered the soil in a solid form. (This
 could very well explain the exceptional result obtained
 In the Harbauer case study).
   If oxidation is used,  production of sludge can be
 avoided. This is, however, only possible for organic
 contaminants that are easily oxidizable, e.g., phenols.
 The In situ extraction techniques  produce a sludge
 containing only the extracted  contaminants and the
 added chemicals in a concentrated form, the volume of
 which amounts to only a small percentage of the soil
 cleaned.  The electro-reclamation technique also
 produces  a small amount of sludge from the water
 purification unit.

 5.6   Limitations or Restrictions to the Use
      of the Techniques
   If the right combination of particle separation
 processes  are used in  combination with extraction,
there are few restrictions for these  techniques in
general. Contaminated soils are considered non-
cleanable if the contaminants are equally adsorbed to
 the entire soil fraction (equal distribution over particle
 size and particle density) and when the contaminants
 are relatively insoluble, thus making separation of any
 fraction  and flushing with  a water-based solvent
 useless.
    Application of the oxidation technique is  limited to
 well oxidizable contaminants. Other oxidizable
 material  present will largely  increase the amount of
 oxidant used. Trials in using oxidants in The Nether-
 lands showed very limited applicability.
    For in situ techniques aiming at removal of con-
 taminants, the contaminants must be readily soluble in
 an aqueous solvent and not be heavily adsorbed onto
 the soil particles. This will only be true for  a limited
 number of cases,  such as the TAUW/Mourik case
 described earlier. Since the mechanism of cleaning by
 electro-reclamation has not been explained,  little can
 be said about its limitations in this respect.
    Any soil that is cleanable in situls also cleanable in
 installations,  but there are additional costs for excava-
 tion and handling of the material. A major drawback of
 in situ techniques in general  is the difficulty  of deter-
 mining  accurate results because of the difficulty in ob-
 taining, without significant cost, accurate concentration
 profiles, both before and after the remediation opera-
 tion. Table 5-2 gives an overview of the limitations of
 the different techniques addressed in this Pilot Study.

 5.7  Costs
    In this section an overview is given of some major
 cost factors that determine the total cleaning costs in
 an extractive  installation. The costs of electro-reclama-
 tion, in  situ acid extraction, and jet cutting followed by
 oxidation were not available at this time.
   The  general overview of costs involved in extractive
 cleaning of soil has been drawn from past experience
 with extractive cleaning of soils in The Netherlands
 (Hinsenveld 1990).   The costs apply  to installations
 such as the Harbauer and Klockner systems, each of
 which will be  largely determined by cost factors men-
 tioned in this section. The cost factors are applicable to
 a lesser extent to the Keller installation, since this in-
 stallation is simpler than the other extraction installa-
 tions from a treatment point of  view.
   This  discussion of costs is not claimed to be com-
 plete and  care must be taken  to take cost factors into
 consideration that are not addressed  here, such as
 cost factors that are specific for an  installation, a
 project,  a country, and so on.
   The costs are given in 1990 US$.

5.7.1  Fixed Costs
   Location.  An extractive installation  is constructed
on an emission controlled site. The costs for such a
site include:
                                                  58

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                                                              Physical/Chemical Extraction Technologies
Table 5-2. Limitations to the use of the case study techniques.
Process/Technique High pressure soil
washing
Manufacturer Klockner
Technique available Germany, The
in Netherlands
In/Ex situ Ex situ


Type of soil Preferably sandy soils.
Not suitable for clay



Fraction of fines Not more than 30% of
the particles smaller than
0.063 mm and organics





Fraction of organics




Fraction of rubble No limitations
Type of No limitations
contaminants




Concentrations of No limitations
contaminants



Production of sludge Double the amount of
the fraction smaller than
0.015 and of the fines


Remarks Buildings on
contaminated site must
be torn down.






Vibration
Harbauer
Germany

Ex situ


Preferably sandy
soils.
Not suitable for
clay

Not more than
20% smaller than
0.015 mm

Not more than
30% smaller than
0.063 mm and
organics





No limitations
No limitations





No limitations




Double the
amount of the
fraction smaller
than 0.063 and
of the organics
Buildings on
contaminated site
must be torn
down.





Jet cutting/
oxidation
Keller
Germany

In situ soil
cutting; ex situ
treatment
Preferably sandy
soils



No limitations







High content of
organic material
leads to
excessive
oxidant use
No limitations
Only easily
oxidizable
components i.e..
phenol;
heavy metals are
not removed
High
concentrations
lead to high
oxidant use

Not produced




Technique can
be used
underneath
standing
buildings.




Electro-
reclamation
Geokinetics
Australia, The
Netherlands
In situ


Suitable for both
sandy material
and clay. For
sand, flushing
might be cheaper
No limitations







No limitations




No limitations
Only proven for
heavy metals




High
concemtrations
can leiad to high
use of electricity

Little; highly
concentrated



Technique can be
used underneath
standing
buildings; Metallic
objects in the
ground leads to
insufficient
cleaning and high
electricity costs.
In situ acid
extraction
TAUW/
Mourik
The
Netherlands
In situ


Sand, with
high
permeability


Not more than
a few percent
smaller than
0.1 mm




Must be very
low or absent



No limitations
Only acid
soluble heavy
metals



High
concentrations
can lead to
high flushing
costs
Little; highly
concentrated



Technique can
be used
underneath
standing
buildings.




Note: A large fraction means more than 30% of the contaminated soil.
                                                    59

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 Chapter 5
   ป The annual costs of the installation site, including
     maintenance of the site itself. These amount to
     about US$150,000 to US$270,000. These costs
     also incorporate a number of facilities of which the
     most important are: the construction of fluid-tight
     underlining, runoff water control and a secondary
     impermeable barrier (about US$50 to US$80/m2;
     these costs are roughly doubled in case a hood is
     needed), and the facilities needed at the site. For
     a s'rte of an average size of 10,000 to 20,000m2,
     the investment, including fences, weigh bridges, a
     carwash facility etc., is estimated to be about
     US$750,000 to US$1,500,000.

   ซ Catchment and treatment of percolation water.
     Percolation water from other parts of the site is
     generally caught separately.  It includes  surface
     runoff from the covered contaminated soil,  sur-
    face runoff from parts of the site that are not in
     use, and surface runoff from roads. Only if the
     contamination is unacceptably high will this runoff
     be treated. Annual costs, depending on the size of
    the s'rte and the type of  contaminant range from
     about US$60,000 to US$90,000.  This brings the
    total  estimated annual costs of  the location to
     about US$210,000 to US$360,000.

   Water discharge. The costs of discharge  are lar-
gely dependent on the size of the site and arrange-
ments made by the local government.  Estimated
annual costs range from US$20,000 to US$30,000.
   Installation of soil cleaning equipment.  The in-
vestments needed for the soil cleaning installation, the
sludge treatment unit, and the treatment of process
water are difficult to specify for every unit separately,
because of major differences  between the installa-
tions. For Installations presently used  in The Nether-
lands, these costs  range roughly from US$2,500,000
to US$4,500,000.  With a depreciation of 5 years and
including necessary maintenance and replacement,
the  annual  costs amount  to  US$660,000 to
US$1,200,000.
   Operation of the Installation. For a direct opera-
tion of a soil cleaning installation, treatment of process
water, filter press sieving, and logistics, some four to
six people are needed. In most countries, this person-
nel frequently must have completed on-s'rte hazardous
waste management training and be certified to work on
the site. The training generally includes practice in the
field of inhalation protection, first aid,  and fire abate-
ment. Annual  costs amount to US$240,000 to
US$300,000.
   Process control and development. Process con-
trol,  making and  evaluating test  cleaning, and  the
evaluation of technology developments  are  mostly
done by an engineer of academic level. Annual costs
amount to US$90,000 to US$120,000.
   Shovels and trucks. Input of soil into the installa-
 tion, on a coarse sieve, is done with help of a shovel or
 a front-end loader. Another truck is needed for remov-
 ing the sludge from the containers. These vehicles
 generally need pressurized cabins and an air filter. The
 costs amount to US$90,000 to US$150,000 per year.
   Licenses. Most commercial firms use one or more
 licenses. Different arrangements have  been made in
 the past for payment. Payment at once, followed by a
 yearly depreciation or payment per year per tonne
 cleaned material are general practices. Estimated
 costs range from US$60,000 to US$90,000.
   Canteen, showers, and offices.  Buildings and
 normal costs like water, electricity, heating, telephone,
 and the cleaning of work clothes and offices amount to
 annual costs of about US$60,000 to US$90,000.
   Other costs. In the field of soil remediation,  costs
 of insurance,  permits, administration, accountants,
 bank guarantees, etc., can be quite substantial. Fur-
 thermore, costs concerning the establishment and
 control of  safety procedures, medical checkup of
 workers, advice from medical doctors as well as  costs
 for depreciation of measurement devices must not be
 forgotten. These annual costs are estimated to range
 from US$90,000 to US$120,000.
   Direction and acquisition.  The pre-project ac-
 quisition and specification of the work can be quite dif-
 ficult in this field. Estimated costs amount to
 US$60,000 to US$90,000.
   A summary of fixed costs is given in Table 5-3.
   These total fixed costs must be divided by the total
 amount of cleaned soil (approved tonnes). With an an-
 nual production of 22,700  tonnes at the lowest and
 40,800 tonnes at the  highest investments, the  fixed
 costs amount to US $68 and US$63 per tonne, respec-
 tively of cleaned soil.

 5.7.2 Variable Costs
   Deposit of soil before treatment. The soil on  ar-
 rival  has to be deposited and covered at the site. The
 trucks used for this operation must be washed before
 leaving the site again. The cost of this operation
 strongly depends on the frequency of deposit. Costs
 are about US$1 to US$2 per tonne of soil.
   Analysis. In order to verify the indicated concentra-
 tions and types of contaminant, as well as to assess
 the expected sludge to be generated after treatment of
 the soil, samples  are taken and analyzed during the
 process of depositing the soil. Analyses are also con-
 ducted for assessing process parameters to minimize
 emissions and residues and to indicate the expected
 quality of the end product (e.g., cleaned soil, sludge).
 These costs strongly depend on the homogeneity of
the soil and the amount of soil being cleaned. Es-
timated costs are US$2 to US$7 per tonne of soil. ,
                                                 60

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                                                            Physical/Chemical Extraction Technologies
 Table 5-3. Summary of annual fixed costs (in US$ 1990).
Cost item
Location
Discharge
Install soil cleaning equipment
Operation of installation
Process control and
development
Shovels and trucks
Licenses
Canteen, showers and offices
Other costs
Direction and acquisition
Lower
values
210,000
18,000
660,000
240,000
90,000
90,000
60,000
60,000
60,000
60,000
Higher
values
360,000
30,000
1 ,200,000
300,000
120,000
1 50,000
90,000
90,000
1 20,000
90,000
   TOTAL ANNUAL FIXED
   COSTS                1,548,000    2,550,000

   TOTAL PER TONNE SOIL        68          63
   Electricity and water.  Energy is needed for most
of the unit operations. Water is needed, because the
soil and the sludge leave  the installation  with an in-
creased water content compared to the original soil.
These costs  strongly depend on the amount of  soil
cleaned per hour and the amount of sludge produced
from the soil.  More fines lead to both higher electricity
costs as well  as a higher water demand. Estimated
costs range from US$2 to US$4 per tonne of soil.
   Chemicals. Depending on the system used in the
extractive soil cleaning installations, the following
chemicals may be  used: chemicals for pH condition-
ing,  emulsifiers  and demulsifiers, coagulants, floc-
culants, and flotation aids. The costs will be a function
of" the type and  concentration of contaminants,  the
chemical composition of the soil,  and the sludge con-
tent. Costs range from US$4 to US$7 per tonne of soil.
   Filter material.  Cleaning of process water and air
is sometimes done  by means of sand filters and active
carbon filters. Both types of filters must be processed
afterwards (i.e., regenerated or deposited). The costs
involved strongly depend on the type and  concentra-
tion of contaminants and are in the range of US$1 to
US$3 per tonne of soil.
  'Safety and occupational health. Depending on
the risk factors, personal protection is needed. In some
cases the presence of a safety and occupational
health specialist  is  required. Costs are estimated as
US$2 to US$7 per tonne of soil.
    Reuse of the cleaned soil. This is still a problem.
 In case the concentrations; are very low (for instance,
 at the Dutch reference levels), the soil can be used
 multi-functionally. In many cases,  the cleaning com-
 pany pays for the transportation costs of this material.
 At higher residual concentrations, the cleaned soil can
 sometimes be used in asphalt production installations.
 The costs,  therefore, depend on the type and con-
 centration of the residual contaminants  and on the
 transport distance. Typical costs in The Netherlands
 range from zero to US$10 per tonne of soil.
    Ultimate disposal  of cleaned soil depends on
 regulatory requirements. It should be noted that even
 when the soil is cleaned to trace concentrations of con-
 tamination,  the public will likely be very  reluctant to
 allow reuse  of the cleaned soil (psychological factors).
    Reuse of rubble, etc.  Rubble and gravel mixed
 with other soil particles which are separated from the
 soil may require treatment, depending on the composi-
 tion. These  coarse materials may be reused in road
 building, but are often deposited  at a landfill site. The
 costs per tonne of material depend on the composition
 of the material, type and concentration of the con-
 taminants, and the distance of transport. A range may
 be indicated as US$17 to US$66 per tonne of rubble.
 For soil containing 10 percent rubble and other non-
 soil materials, this amounts to US$2 to US$7 per tonne
 of soil.
   Reuse of sludge. The mineral fraction (mostly the
 fraction smaller than  0.063 mm to 0.030 mm) is trans-
 ferred from the soil to the water phase and finally ends
 up in the sludge. Usually the sludge will be processed
 by a  mechanical dewatering unit.  The sludge, in
 general,  contains the larger part  of the contaminants
 (most contaminants are heavily adsorbed on this frac-
 tion). Deposit of this material may be expensive due to
 its high concentrations of contaminants, such that only
 controlled and permitted landfills will accept the
 sludge. The  cost of disposal will be dependent on the
 amount of the  minimal fraction  in the soil (fraction
 smaller than 0.063 mm to 0.030 mm), the distance of
 transport, and the cost of landfilling. A soil with 10 per-
 cent mineral content  leads to estimated costs of dis-
 posal of US$7 to US$46 per tonne of soil. If the sludge
 has to be treated   before  deposit, by  solidifica-
 tion/stabilization techniques: for example (see Chapter
 3), the costs will be a multiple of the above mentioned
 figures.
   A summary of variable costs is given in Table 5-4.

 5.7.3 Total Costs
   From the  inventory above it is clear that the costs of
 cleaning soil depend on a large number of factors. This
 inventory is based on experience  in The Netherlands;
this should  be  borne in  mind  when  calculating the
costs  for other countries. Some of  the item costs
probably will be very different and  the costs given here
                                                 61

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Chapters
Table 5-4. Summary of variable costs per tonne soil (in
          US$, 1990).
  Cost Item
                              Lower
                              values
Upper
values
  Deposit of soil before
  treatment
Analysis
Electricity and water
Chemicals
Filter material
Safety
Rouse of cleaned material
Rouse of rubble, etc.
Deposit of sludge
TOTAL VARIABLE COSTS
2
2
4
1
2
0
2
7
21
7
4
7
3
7
10
7
46
93
should, therefore, not be used as a direct reference for
estimating costs. Furthermore it is expected that a
number of other costs not mentioned here might be
added to  the calculation for certain countries. The
above method of calculating the treatment costs
should, therefore, only serve as an example of how a
Table 5-5. Total costs of extractive treatment per tonne
          soil (in US$,1990).
                                Lower
                                values
Higher
values
 Total fixed costs                  68        63

 Total variable costs                21        93

  TOTAL COSTS OF TREATMENT     89       156
rough calculation might proceed. The total costs of
treatment are indicated in Table 5-5.
   In general, the costs for treatment in The Nether-
lands on the basis of 10 percent rubble and 10 percent
sludge will vary between US$89 and US$156. In the
above  mentioned inventory,  general administration
costs and the costs of profit have also been omitted.
Commercial firms add in general  about 10 percent to
15 percent to the above mentioned figures for this pur-
pose. In addition research and  development costs
have been omitted.

5.8   Future Status of Case Study
      Processes and Extraction
     Technologies as a  Whole
   As indicated, extractive methods are suitable for a
large range of soils and a large range of contaminants.
The  ex situ extraction methods are powerful techni-
ques for soils containing heavy metals as well as or-
ganic contaminants. For soils containing a combination
of metals and organics,  there are presently no other
techniques  available. For soils  containing only or-
ganics, thermal techniques are generally more effec-
tive. A further improvement  of the extraction
installations by using new separation techniques is ex-
pected. The use  of organic solvents and supercritical
extraction techniques are being investigated at the mo-
ment. These techniques might further enlarge the ap-
plicability of the  extraction techniques, but are
generally more expensive. The Keller technique, using
only  oxidation, has a limited applicability. The jet cut-
ting method used in the cleanup  operation, however,
might be useful to reduce the  costs of cleanup under
buildings, because the buildings would not need to be
dismantled.
   In situ extraction techniques will probably continue
to play only  a marginal role  in the cleanup of con-
taminated sites dye to their limited applicability.
   However, the electro-reclamation technique could
prove to be a powerful technique for solving problems
associated with cleaning clayey soils and sludges, but
is still under development. For in  situ cleaning of clay
soils containing heavy  metals, electro-reclamation is
the only technique available at the present time.  For
that reason,  electro-reclamation deserves to be invesr
tigated intensively in order to assess its potential.
                                                  62

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                                                          Physical/Chemical Extraction Technologies
REFERENCES
                                            demonstration of a pi.ot-sca.e debris washing system. Journa.
    Casagrande, L.J. Boston Society of Civil Engineers, 69 (2) 1983, pp 255-302.
             ^kf ฐuฐ'' W" a?? Sff"98' GA  Elซ=ปro-reclamatlon: State of the art and future developments

           Dordrechl!T9e9noV        Va" **" Brink (8ds0> Contaminated Soil >9ฐ- Kluwer Academic Pub

    U.S. EPA  Technology evaluation report: Design and development of a pilot-scale debris decontamination •
    system, Volume 1. EPA/540/5-91/006a, U.S. Environmental Protection                             ^
                           innฐVative tecnnolฐ9y evaluation program: Technology profiles.  EPA/540/5-
                                              63

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 Pump and Treat Ground Water

 James W. Schmidt
 Wastewater Technology Center, Rockdiffe Research Management, Inc.
 867Lakeshore Road, Burlington, Ontario L7R 4L7
 Canada
ABSTRACT

   Four pump and treat ground water case studies were chosen for the Pilot Study.  The first three deal with an
evaluation of treatment technologies. The first of these evaluates the use of more conventional processes: air stripping
and activated carbon adsorption at full scale; the second concerns advanced photo-oxidation technology (at pilot
scale). Generally, the types of contaminants treated were volatile organic compounds and a few other nonvolatiles
such as phenols and PCB's. The third evaluates the use of precipitation and clarification for removing cadmium and
zinc from contaminated ground and surface waters from an old zinc smelting operation.
   The final case study deals with minimizing the quantity of water to be treated with a concurrent reduction in the
amount of contaminants to be treated. A particular well pumping technique was examined also at pilot scale at the
W3STS sitG in Dฉnm3rk.


                                                   contaminants from the aquifer.  In addition, con-
                                                   taminants that are adsorbed or held by the soil par-
                                                   ticles may be desorbed from the  soil particles,
                                                   maintained  in solution in the ground water, and
                                                   pumped out at the extraction well.
                                                      In all cases, for decontamination to be effective,
                                                   sources contributing to the contamination of the
                                                   ground water must be removed, such as, sludge
                                                   ponds, buried drums, and nonaqueous phase liquids in
                                                   the soil matrix.

                                                   6.2  Case Studies Chosen
                                                      In terms of system design for pump and treat, the
                                                   hydrogeological and geochemical properties of the
                                                   aquifer must be known, as well as the behavior of the
                                                   contaminants within the aquifer and the ground water.
                                                   Extraction wells can be designed from basic hydrologic
                                                   principles to ensure that an appropriate "cone of in-
                                                  fluence" exists.
                                                      There are a number of factors to be considered in
                                                  designing a treatment sys;tem.   These are  indicated
                                                  briefly here and  elaborated on in Section 6.6. One
 6.1   Introduction
   This chapter deals with pump and treat technology,
 with the primary emphasis on treatment technologies
 for pumped ground water. Outlined in this chapter are
 four case studies, the performance of various tech-
 nologies, lessons learned, costs, factors to be con-
 sidered for using the technologies and, finally, the
 future of the technologies demonstrated.
   Pump and treat technology consists of the extrac-
 tion  of contaminated ground water from the subsur-
 face, followed by treatment of the ground water at the
 surface  to remove the contaminants.  Treatment can
 be by means of  physical/chemical technologies,
 biological treatment technologies,  or any appropriate
 combination of these.
   The application of pump and treat technology can
 be considered for essentially two cases: containment
 of the contaminants  in the ground water to within  a
 confined zone thereby preventing the spread of the
 contamination, and decontamination of the aquifer.  In
this  latter case, injection wells may be  installed
 "upstream" of the  pumping well(s) to help  flush the

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Chapters	

consideration is the actual treatment process(es) that
will be used.  The treatment processes will be a func-
tion of the type and quantity of contaminants present
as well as the volume of ground water to be treated.
The quantity of contaminants and volume of water to
be treated can also impact  significantly on treatment
costs.  This factor may be overlooked but it is  highly
desirable to examine the possibility of reducing the
volume of water to be treated and,  if possible, the
quantity of contaminants to be treated. It is essential
that the treated ground water and any residuals or
emissions meet the regulatory requirements.
   To partially illustrate these points, four case studies
were chosen.  One case study illustrates flow and con-
taminant minimization and  the other three illustrate
various ground water treatment technologies.
   One other case study is outlined in Chapter 8 below
which also relates to this chapter on  pump and treat
technologies.  This case study is biological pretreat-
ment  of ground water, The Netherlands (Lin-
dane/Bunschoten).   An additional project report  is
included in Appendix  1-C: on-site in situ reclamation:
membrane filtering  and biodegradation, Denmark
(former gas works site/Fredensborg).

6.2.1 Case Study 6-A: Decontamination of Vllle
      Mercler Aquifer for Toxic Organlcs, Vllle
      Mercler, Quebec, Canada.
   This case study was chosen for two reasons. First-
ly, it Is a demonstration of a  full scale "pump and treat"
system, the first in Canada and  perhaps North
America, designed to decontaminate  an aquifer.
Secondly, an evaluation of the treatment technologies
 employed  (a combination  of "air stripping" and ac-
tivated carbon) was being undertaken by Environment
 Canada.
    Site. From 1968 to 1972 some 40,000  m3 of waste
 oils and liquid industrial wastes from chemical and
 petrochemical industries in the vicinity of Montreal,
 Quebec were dumped in a  lagoon in an old gravel  pit
 located near Ville Mercier, Quebec.  The dump site
 was  closed  in 1972.  Over the next 10  years,  as a
 result of several investigations, it was determined that
 about 30 km2 of  the  aquifer supplying drinking water
 for several local communities was contaminated.
    The gravel pit is located  in a sand and gravel esker
 of f luvio-glacial origin. The sand and gravel extend to
 a depth of roughly  30 meters and overlie fractured
 dolomite and sandstone bedrock.  The most con-
 taminated zone extends over an area of about 2 km2
 down gradient from the lagoon.
    The climate in the area  is typically temperate, with
 snow and rain averaging about 254 cm per year.  Cold
 weather extends generally  from mid October through
 mid April.
    Treatment System.  The installation became
 operational  in 1984.  Three ground water extraction
wells were located down gradient from the lagoon and
provided a flow of 65 L/s to the treatment plant. The
primary treatment processes involve air stripping to
oxidize  and precipitate iron and manganese and to
remove volatile organic compounds (VOC's); coagula-
tion and flocculation with alum and polymer addition;
sedimentation and rapid sand filtration to remove iron
and manganese and other suspended solids.  Ac-
tivated carbon is used to remove the remaining organic
compounds. More detailed information is provided in
the references at the end of this chapter and in Appen-
dix 6-A.

6.2.2  Case Study 6-B: Evaluation of
      Photo-oxidation Technology (Ultra*1*
      International), Lorentz Barrel and Drum
      Site, San Jose, California, United States.
   This case study was chosen because it was the
evaluation  of a photo-oxidation process to  treat or-
ganics in a contaminated ground water.  This technol-
ogy was evaluated under the  Superfund Innovative
Technology Evaluation (SITE) program of the  United
States  Environmental Protection Agency (U.S. EPA).
The demonstration took place in February and March
1989 at a former drum recycling facility in San Jose,
California.
   Site. In 1947, Lorentz Barrel and Drum began its
drum recycling operations. Drums were  received from
over 800 private companies as well as military bases,
research laboratories and county agencies in Califor-
nia and Nevada.  The drums generally contained
residual aqueous wastes, organic  solvents, acids,
metal oxides, and oils.  Residual wastes from drums
and wastewaters were  disposed of  in an on-site
drainage ditch routed to a large sump.  Prior to 1968,
wastewater from the sump was discharged to the
 storm drain system.  In subsequent  years, discharge
was to the sanitary sewer. This practice was discon-
tinued between 1983 and 1984.  Subsequently, liquid
wastes were reportedly reduced in volume by evapora-
 tion, put in drums, and disposed of off-site as hazard-
 ous wastes. In 1987, the facility ceased operation and
 the U.S. EPA Regional Office in California assumed
 lead  agency responsibility for site remediation and in-
 itiated a remedial investigation/feasibility study. When
 the company began operations, the site consisted of
 25.9 hectares.  Since then half has been sold.  The
 highest contamination levels are suspected to be in the
 remaining 13 hectares.
    The surface soils are  silt and clay (about 1 meter)
 underlain by sand and gravel, about 7 meters below
 which there is a clay aquitard.  The water table occurs
 at a depth of approximately '6 meters.  The  shallow
 ground water flow appears to follow the ground surface
 topography flowing towards a local watercourse,
 Coyote Creek, about 0.8 km away.       '      :
                                                   66

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                                                                        Pump and Treat Ground Water
    The climate in the area has warm, dry summers
 and cool, wet winters.  Normal average rain fall is 353
 mm (13.9 inches) most of which occurs from Novem-
 ber through April.
    Treatment Process.  The Ultroxฎ technology (a
 registered trademark  of Ultrox  International)  simul-
 taneously uses  ultraviolet radiation, ozone  and
 hydrogen  peroxide to  oxidize dissolved organic con-
 taminants (including chlorinated hydrocarbons  and
 aromatic compounds)  found in ground water or was-
 tewater.
    The objectives of the technology demonstration
 were to:
    • Evaluate the ability of the technology to treat the
     44 volatile organic contaminants found  in  the
     ground water at the site

    • Evaluate the effects of major process parameters
     on process performance

    • Evaluate the efficiency of the ozone decomposer
     unit in treating off-gas from the reactor

    ซ Develop information useful for evaluating whether
     this technology is suitable for other hazardous
     waste sites with similar conditions.

    Five variables  examined during  the 10-day pilot
 scale test included hydraulic retention time, ozone
 dose, hydrogen peroxide dose, UV radiation intensity,
 and influent pH level.  To facilitate the test program,
 three indicator VOC's were selected:  trichloroethylene
 (TCE) 1,1-dichloroethane (1,1-DCA) and  1,1,1-
 trichloroethane (1,1,1-TCA).  At a flow rate of 14 Lpm
 3.75 gpm, the reactor retention time was 40 minutes.
 This was varied between 20 and 60 minutes. Addition-
 al details are presented in the references at the end of
 the chapter and in Appendix 6-B.

 6.2.3  Case Study 6-C: Zfnc Smelting Wastes and
      the Lot River, Viviez, Averyron, France
   This case  study was chosen because it  repre-
 sented an example of a "pump and treat" system and
 the contaminants of concern were metals (in contrast
 to organics).
   Site. Zinc  production in Viviez was started in the
 1870's.  Until 1930, a thermal process was used to ex-
 tract the zinc from the ore with the wastes being dis-
 posed of on a hillside near the plant.  After 1930,  an
 electrometallurgic process was used and again the
wastes were deposited near the plant.  The total, now,
 is  about 700,000 tonnes. Water percolating through
the wastes dissolves cadmium and zinc which reach
the ground water and eventually, surface water.  In
 1987, it was calculated that 37 kg/d of cadmium were
reaching the Lot River.  Hydrogeological studies were
undertaken to better define the hydrodynamic be-
haviour of the  alluvial aquifer, the hydraulic relation-
  ship between the waste heap and the aquifer, and the
  surface water regime in the vicinity of the heap.  Addi-
  tional water analyses were done on various chemical
  parameters as well.
    In 1988,  action was taken to cover ponds on the
  heap, to relocate the smallest storage piles, and collect
  contaminated surface and ground water.  With these
  actions, the cadmium flux was reduced by 94 percent
  to 2 kg/d.  Several additional actions, such as flushing
  parts of the heap and diverting surface water, resulted
  in reduced quantities of contaminated water to be
  treated.
    Treatment Process.  The treatment is performed
  in a batch mode with 320 to 800 m3 of contaminated
  water collected in any one day. The process involves
  the addition of lime in several reactors followed by the
  addition of sodium sulfide.  Polymer is added to the
  clarifier to ensure effective settling of the sludge and to
  ensure that the effluent objectives are  met.  The
  sludge is dewatered on a filter press  and sent off-site
 for metal recovery.  The effluent is  discharged to  a
 receiving water.  Additional work is underway to further
 reduce the quantity of water (and contaminants) to be
 treated and,  hopefully, reduce the  cost of treatment.
 Additional details are presented in Appendix 6-C.

 6.2.4  Case Study 6-D:  Separation Pumping,
      Skrydstrup, Denmark
    This case  study  was  chosen  because it
 demonstrated the use of a novel pumping technique,
 separation pumping, to reduce the volume of ground
 water and the quantity of contaminants to be treated.
    Site.  In the  period 1963-1974, chemical waste
 from a  refrigerator factory was dumped in a gravel pit
 near  Skrydstrup  in western Denmark.   The ground
 water was considerably contaminated by 1,1,1
 trichloroethane and organic phosphorus.  The waste
 was excavated in 1986.  The drums with chlorinated
 solvents were sent for destruction and the con-
 taminated soil was placed in a special waste disposal
 site for treatment. (For more details, refer to Appendix
 6-D.)  The  pollution plume has been found up to 1.5
 km downstream and to a de;pth of 25 meters.
    Technique. This technique relies on simultaneous
 pumping from the top and bottom of a fully penetrating
 well through the  polluted  section of the aquifer.  The
 objective is to reduce the volume of  water requiring
 treatment.  In a test well, during the  period July-Oc-
 tober  1989, from  50 to 65 percent of the total water
 pumped was within acceptable limits of contaminants -
 obviously a significant reduction in the volume of water
 that would have  to be treated.  In the  subsequent
 period,  November 1989  to March 1990, the pump
 ratios had to be changed such that only 10 percent of
 the total discharge was within acceptable limits;  still,
 however, producing a reduction in the volume to be
treated.  Additional pilot scale  experiments with en-
                                                 67

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Chapters
couraging results were also completed in a limestone
aquifer and a chalk aquifer. As these were only pilot
scale experiments, no cost data are available yet for
full scale application.  Additional details are provided in
Appendix 6-D.

6.3  Background of the Case Study Sites
      as a Group
    Only three  of the four case studies mentioned
above will be used to demonstrate the performance of
treatment technologies.  Before  describing the perfor-
mance results,  background information is provided on
the sources  and types of contaminants,  some site
characteristics, and the success in  remediating one
aquifer. The sources of contamination are set out in
Table 6-1.
    Table 6-1.  Sources of contamination at case study sites.
      Site
      Ville Mercier
      Lorentz Barrel and
      Drum

      Lot River
                            Source
Waste dump in a rural area
containing primarily organic
wastes and oils.  Some PCB's
detected.

Decommissioned industrial site in
an urban area.

Old industrial site near an urban
area.
Table 6-2. Principal contaminants at the Ville Mercier, and the Lorentz Barrel and Drum sites.
  A. Villa Mercier
                                                       B. Lorentz Barrel and Drum'
  Phenols'
  1,2-Dichloroethane (1.2 DCA)'
  1,1,1-Trichloroethano (1.1.1-TCA)1
  1,1,2-TrichloroethanD (1.1,2-TCA)
  Trichloroethylene (TCE)1
  Chloroform
  Chlorobonzone
  Trans 1,2 Diohloroathylene
  PCB's1
  Iron
  Manganese
Benzene2
Benzyl Chloride
Bis (2-chloroisopropyl) ether
Bromobenzene
Bromodichloromethane
Bromoform
Bromoethane
Carbon tetrachloride
Chloracetaldehyde
Chloral
Chlorobenzene
Chloroethane3
Chloroform3
1-Chlorohexane
2-Chloroethyl vinyl ether
Chloromethane
Chloremethyl methyl ether
Chlorotoluene
Dibromochloromethane
Dibromomethane
1,2-Dichlorobenzene
1,3-Dichlorobenzene
1,4-Dichlorobenzene
Dichlorodifluoromethane
1,1 -Dichloroethane2'3
1,2-Dichloroethane3
1,1-Dichloroethylene3
  Trans-1,2-dichloroethylene3
  Diohloromethane
  1,2-Dichloropropane3
  1,3-Dichloropropylene
  Ethyl benzene
  1,1,2,2-Tetrachloroethane
  1,1,1,2-Tetrachloroethane
  Tetrachloroethylene3
  Toluene
  1,1,1-Trichloroethane2'3
  1,1,2-Trichloroethane
  Trichloroethylene2'3
  Trichlorofluoromethane
  Trichloropropane
  Vinyl Chloride
  Xylenes
  Arsenic4
  Barium*
  Chromium*
  Cobalt*
  Iron
  Manganese
  Molybdenum*
  Nickel*
  Vanadium*
  Zinc*
 'Contaminants selected to evaluate the performance of the technology.
 'Contaminants selected as "indicator" VOC's to guide the test program at Lorentz.
 'Principal contaminants measured for test work.
 4Motals found in wells on-site but not reported in test work.
    Table  6-2 identifies the principal contaminants at
 Ville Mercier and Lorentz Barrel  and Drum.  Volatile
 organic compounds (VOC's) and some  PCB's were
     found at both sites.  In the case of Lot River, the con-
     taminants of concern are the toxic  metals, zinc and
     cadmium.
                                                        68

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                                                                           Pump and Treat Ground Water
    The site characteristics of the case studies were
 significantly different.  As the focus of the chapter is
 primarily on treatment technologies, the  type and
 range of site characteristics are not particularly
 relevant.

 6.4  Performance Results

 6.4.1 Effectiveness of Aquifer Remediation at Ville
      Mercier
    It was anticipated that the  aquifer would be
 remediated within a period of five years based upon
 the predesign hydrogeological investigations, the site
 investigations that were conducted as part of the 1989
 study clearly indicated that this did not occur  nor would
 it likely occur within the foreseeable future.  The
 reason for this was that, when additional monitoring
 wells were placed and sampled, significant  quantities
 of nonaqueous phase liquids (NAPL)  were  found
 throughout the soil and into the  fractured  bedrock.
 Thus, although the pumping appeared to be effectively
                constraining the down gradient movement of con-
                taminants, it was obvious that the aquifer could not be
                remediated until some means was found to remove the
                NAPL.

                6.4.2 Effectiveness of Treatment Technologies
                    Each of the  treatment systems'.at the three sites
                were judged using a similar basis, i.e., that the ef-
                fluents and emissions had to meet regulatory stand-
                ards. The specific objectives to be met are presented
                in Tables 6-3 and 6-4. The effectiveness of the treat-
                ment systems at Ville Mercier and Lorentz Barrel and
                Drum was assessed  by how well they removed the
                contaminants of concern priimarily VOC's and if the ef-
                fluent criteria were met. For the Lot River case study,
                the process was assessed on its ability to reduce zinc
                and cadmium.
                   Ville Mercier. A review of the results of the perfor-
                mance of the treatment plant from 1984 to 1989 (Ap-
                pendix 6-A) and during the two sampling campaigns
                undertaken in  1989 reveals that there were a number
Table 6-3. Performance results for Ville Mercier, and Lorentz Barrel and Drum sites.


                                                        Results in figlL (unless otherwise noted)
  Compounds
                                                 Ville Mercier
Objective
                                                       Results
                                          Lorentz Barrel and Drum

                                                	Results6
Objective4   Run 12"    Run 13e
Iron (mg/L)
Manganese (mg/L)
RGB's
Phenols
Benzene
Chloroform
Chloroethane
1 , 1 -Dichloroethane
1 ,2-Dichloroethane
1 , 1 -Diohloroethylene
Trans-1 ,2-Dichloroethylene
1,1,1-Triohloroethane
1 ,1 ,2-Trichloroethane
Trichloroethylene
1 ,1 ,2,2-Tetraohloroethane
Tetrachloroethylene
1 ,2-Diohloropropane
Vinyl Chloride
Any other VOC
0.30
0.05
0.01
2.0
50



50


33
50
4.5




50.00
0.02 0.01

nil

78.0 27.0



620 1 23


nil nil
441 25.0
1 1 .0 1 .0









5.0
5.0
5.0
5.0
1.0
5.0
5.0
5.0

5.0
5.0
5.0
5.0
0.5

low
low


0.23
0.74
0.00
3.80
0.92
0.00
0.00
0.43

0.55
0.045
0.19
2.60
0.11

low
low


0.45
0.81
0.00
4.20
1.00
0.00
0.00
0.49

0.63
0.045
0.091
2.90
0.12

Ville Mercier - Oxidation-air stripping followed by suspended solids removal and activated carbon. Lorentz Barrel and
 Drum - Ultroxฎ process consisting of the use of hydrogen peroxide, ozone and ultraviolet light.
2Campaign conducted 4 months after granulated activated carbon (GAC) replacement; period - two weeks.
3Campaign conducted immediately after GAC replacement; period - six weeks.
""Regulatory threshold.
'Thirteen volatiles identified - only 3 common to both sites.
6Mean values; Runs 12 and 13 were replicate runs.
                                                   69

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Chapter 6
Table 6-4.  Performance results for Lot River site.
Effluent
pH
Suspended solids
Phosphorus
Hydrocarbons (total)
Motals (total)
(Zn + Cu + Ni + Al
+ Fo + Cr + Cd +
Pb + Sn)
Zino
Cadmium
Monthly average
Maximum daily
Objective
5-9
<30 mg/L
< 10 mg/L
<5 mg/L
< 1 5 mg/L
<5 mg/L
0.2 mg/L
0.4 mg/L
Results (daily
average)
8.5-9
N/A
N/A
N/A
N/A
0.5 - 3.0 mg/L

0.03- 0.18 mg/L
 N/A ป Not available
 of problems associated with various unit operations in
 the treatment train.  The initial unit operation, consist-
 ing of a packed column, was designed for iron oxida-
 tion and, to some extent, stripping of the VOC's. Iron
 was oxidized effectively; however, the column packing
 quickly became coated with an iron colored scale.
 Removing the scale added to maintenance of the sys-
 tem. The packed column had not been designed as an
 efficient air stripping device and therefore the perfor-
 mance results for VOC's are inferior to those expected
 from a column designed specifically as an air stripper.
   The carbon columns failed to perform as well as
 required, so effluent quality objectives were not consis-
 tently met.  For example, 1,2-DCA "broke through" the
 carbon within  two to three weeks after replacement.
 This may have been due to factors such as competi-
 tive adsorption with other VOC's or generally with the
 other organics present measured as "total organic
 carbon", or simply because 1,2-DCA is poorly adsor-
 bable.
    Significant changes in the influent concentration of
 VOC's likely impacted on the performance of the treat-
 ment train as well.  As an example, the concentration
 of 1,2-DCA increased about ten times over what was
 expected from the initial pump well tests. Therefore, in
 summary, a number of factors contributed to the in-
 ability of the treatment system to consistently meet the
 effluent objectives.
    Lorentz Barrel and Drum.  The Ultroxฎ process
 was evaluated for a period of 10 days during which five
 variables were examined and 13 runs conducted.
 Given an initial set of conditions based upon  a
treatability study, the objective of the evaluation was to
determine a set of operating parameters under which
the process effluent would meet the permit require-
ments. The objective was met and a set of operating
conditions was defined.
   The preferred operating conditions, determined in
the demonstration are the following:
   • Electricity 11  kw/h operation  (24 UV lamps
     operating)
   • Ozone 110 mg/L
   • H2Oa-13mg/L
   ป Influent pH - 7.2 (unadjusted)
   • Retention time - 40 minutes
   • Flow rate-14 L/min
   • Reactor - 568 liters wet volume
   ป Cooling water -13 L/min.

   Lot River. Although information on the treatment
process was provided, there was  no information
provided on the long term operation of the treatment
process.  The data provided  indicate that for the me-
tals of concern, zinc and cadmium, the effluent objec-
tives were easily met.

6.4.3 Lessons Learned on How to Improve
      Effectiveness
   Ville Mercier.  Because of the unexpected finding
of NAPL at the site several years after the treatment
system had been operating, the need for comprehen-
sive hydrogeological/geochemical investigations to be
undertaken prior to  initiating  the pump and treat sys-
tem was clearly underscored.
   As noted, a number of factors impacted on the per-
formance of the treatment system. As a result, the fol-
lowing needs have been identified:
   • Comprehensive treatability studies should be un-
     dertaken prior to design.  These should be at
     bench and pilot scale (preferably at the site to be
     cleaned up).

   • More comprehensive hydrogeologic/geochemical
     information should be obtained before a remedia-
     tion scheme is implemented.

   • Ground water treatment plants should be
     designed with flexibility  so that the performance
     can be optimized under variable influent condi-
     tions.

    As an integral part of the 1989 Ville Mercier study, a
 pilot plant was constructed and operated to determine
 if a different combination of  unit  operations would be
 appropriate to treat the ground water. The pilot plant
 study was conducted from January through July 1989.
    The unit operations tested and selected as being
 appropriate for a treatment train were:
                                                  70

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                                                                        Pump and Treat Ground Water
    ซ Diffused aeration followed by sand filtration for
     iron removal

    ป Optimized, packed,  air stripping column for the
     removal of VOC's

 ,   • Activated carbon for polishing purposes (TOC's,
     phenolics).

    Because the air stripping column was optimized ori
 the basis of 1,2-DCA being the limiting contaminant, it
 was found that the existing discharge objectives could
 be met using only this unit operation (with pretreatment
 for iron removal).
    Lorenfz Barrel and Drum.  The period of the tech-
 nology evaluation was limited to 10 days.  Although an
 appropriate set of operating conditions was defined to
 meet the objective of the demonstration, these were
 not necessarily either an optimum set or the most cost
 effective.
    Lot River.  It is difficult to draw  significant con-
 clusions given the limited  information provided.  How-
 ever,  it  should be  noted that the  usefulness of
 minimizing the volume of contaminated water and the
 quantity of pollutants to be treated appeared to, have a
 significant impact on  the treatment system and the
 receiving water. The treatment process, as designed,
 effectively removed the metals of concern to accept-
 able levels.

 6.5  Residuals and Emissions
   Ville Mercler. From this plant, there were air emis-
 sions,  sludge from the clarifier and spent activated
 carbon.
   The air emissions were acceptable to the  local
 regulatory authority, the Ministry of the  Environment of
 Quebec (MENVIQ). The  sludge was  analyzed  for a
 variety of chemicals and found acceptable for disposal
 in a local sanitary landfill.  The spent activated carbbn
 was returned to the supplier in the United States for
 regeneration.
   Lorentz Barrel and Drum.  A "Decompozon" unit
 (for which no  process or technical details were
 provided) was employed to destroy residual ozone and
 residual VOC's that were present in the "air emission.
 This unit successfully reduced the contaminants to ac-
 ceptable levels.
   Lot River.  The residual from the process was a
 sludge containing significant concentrations of zinc
 and cadmium. The sludge was dewatered, using a fil-
ter press producing a cake of 20-30 percent solids con-
taining  zinc (25 to 35  percent), cadmium (0.2 to 0.5
percent),  and calcium  (1.5 to 6 percent).   The dried
sludge was shipped off-site for metal recovery.
 6.6  Factors and Limitations to Consider
      for Determining Applicability of the
      Technology

 6.6.1 Application of Pump and Treat
   The nature of the "pump and treat" technology
 limits its use to situations where a realistic quantity of
 water can be pumped out of a contaminated aquifer
 within a reasonable period of time, particularly if the
 goal is to decontaminate the aquifer.
   This technology will only be applicable to situations
 where the soils are relatively permeable,  and where
 the contaminants in the ground water are well defined,
 both  in terms of the chemical  nature of the con-
 taminants and their  behaviour in  the soil and ground
 water matrix.
   All sources of contamination must be removed in
 order for the cleanup to be successful.  This includes
 obvious sources such as  buried tanks, drums, etc.,
 and also less obvious sources, such as "pockets" of
 nonaqueous phase liquids.

 6.6.2  Application of Ground Water Treatment
      Technologies
   • Comprehensive  hydrogeological and  geochemi-
    cal characterization of the site must be completed
    in order to identify the treatment system design
    requirements, such as the volume of flow; the
    quantity,  type and nalture of contaminants; and
    probable variability in contaminant concentra-
    tions.

Application of Air Stripping and Activated Carbon

   • Appropriate treatability studies should be con-
    ducted to identify the design parameters for the
    air stripper and  activated  carbon  adsorbers. At
    this stage, pretreatment requirements  should be
    identified  and appropriate design parameters
    developed.

   • Effective removal of volatile organic compounds
    and other adsorbable organic compounds will be
    accomplished when the process train is properly
    designed.

   • Pretreatment will be required for the removal of
    iron and  manganese, oil  and  grease  and
    suspended solids.

   • If metals  are present, some form of  additional
    treatment  (pre or post) will  have to  be incor-
    porated into the treatment train.

   • Chemicals  may need to be added to control
    microbiological growths in the various units.
                                                71

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Chapter 6	

   ป Air emissions may or may not be acceptable to
    the regulatory authorities; a number of tech-
    nologies exist to control the emissions from air
    strippers.

   • Means of disposal of activated carbon (and any
    other process residues) needs careful considera-
    tion; the spent carbon may be considered a haz-
    ardous waste.

Application of Photo-oxidation Technology

   "The chemistry  of the process is quite complex
    when a number of different organics  are being
    treated. Therefore the process cannot be mathe-
    matically modelled, nor can oxidant dosage be
    based  on stoichiometric relationships  to the or-
    ganics present. This means that the appropriate
    operating conditions and oxidant dosages can
    only be determined through treatability experi-
    ments at an appropriate scale.

   " Effective for removal of volatile  organic com-
    pounds and other nonvolatile organic compounds.

   ซ There are no residues generated by the process.

   • Electrical power requirements for the process are
    significant and require careful consideration.

   " Hydrogen peroxide is the only chemical required
    and must be readily available.  This is not seen as
    a significant problem.

   ป Pretreatment will be required for the  removal of
    iron and manganese, oil and  grease,  and
    suspended solids.

   ปIf  metals are present, some form of  additional
    treatment (pre or post) will  have to be incor-
    porated into the process train.

   • Based on the gas chromatography (GC) and gas
    chromatography/mass spectroscopy analysis per-
    formed for VOC's, semivolatile  organics  and
    PCB's/pesticides, no new compounds were
    detected in the treated  water.   The organics
    analyzed by GC methods represent less than 2
    percent of the total organic carbon (TOC) present.
    Very low TOC removals occurred, which implies
    that partial oxidation of organics (and not com-
    plete conversion to COa and HaO) took place in
    the system.

   ซVariability in the concentration of influent con-
    taminants to the process must be carefully con-
    sidered as the operational parameters for the
    process can only be set for a given set of influent
    concentrations.  Presumably, continuing
    treatability testing would be required to determine
    the appropriate level of the operating parameters
    for a significant change in the influent concentra-
    tion of organic compounds. Another option to ac-
    commodate variability may be the installation of
    equalization capability.

   • Presumably, there is no limit on the concentration
    of organics that can be successfully treated. The
    limiting factor will be cost, primarily for oxidants
    and for power: ultraviolet (UV) lights are relatively
    inefficient, e.g., 0.1  percent.

Application of Precipitation Technology

   • Treatability studies at an appropriate scale are es-
    sential.

   • Effective for removal of cadmium and zinc and
    many other heavy metals.

   • Variability of the volume of water to be treated will
    impact on system design, e.g., tank sizes required
    and must be carefully considered.

   • Not all metals can be removed using lime and
    sodium sulfide and, therefore, the solubility of me-
    tals in relation to pH must be carefully considered.

   • Residual sludge may present a disposal problem
    in some jurisdictions.  Recovery of the metal
    values appears to be an attractive option.

   • The quantity of lime required for precipitation is
    relatively insensitive to the concentration of me-
    tals to be treated.  However,  the  quantity of
    sodium sulfide to be used is a direct function of
    the quantity of metals to be treated.

6.6.3  Availability of the Technologies
   All the technologies are commercially  available.
However, they have to be appropriately designed to
suit the site and  contaminated ground water charac-
teristics.  Technologies and process trains can either
be designed by consultants, or proprietary  "commer-
cial packages" can be purchased from various sup-
pliers.

6.7  Costs
   Ville Mercier.  The plant was constructed and be-
came operational in 1984. The total capital cost for the
treatment facility including the purge wells was
Cdn$3.1 million (Simard 1987).  The operating costs
for the plant are set out in Table 6-5.  Over the period
of operation from 1984 to 1987, it can be seen that the
unit operating costs decreased significantly from
US$0.70  to US$0.39/m3 and  was projected to
decrease to US$0.32/m3. It should be  noted that the
relative cost of the activated carbon is a significant ex-
pense and, therefore, steps to minimize this cost would
be desirable.

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                                                                         Pump and Treat Ground Water
Table 6-5.  Ville Mercier operating costs, (x 1,000 CDN$).

FIXED COSTS2
VARIABLE COSTS3
Maintenance
Electricity
Chemicals
Activated carbon
SUPPLEMENTARY COSTS4
TOTAL COSTS
Volume treated (10egal)
Operating time (%)
UNIT COSTS (Cdn$/103 gal)
(US$/m3)
1984/85
270.0
11.0
41.1
60.3
222.7
172.7
777.8
181.8
34.5
4.30
0.70
1985/86
307.0
16.5
57.9
108.0
271.0
65.6
826.0
284.0
54.1
1 2.90
0.48
1986/87
283.7
22.4
59.8
145.0
210.3
152.6
873.8
369.1
70.3
2.37
0.39
1987/881
212.9
22.0
76.0
168.0
290.0
133.8
902.7
420.0
80.0
2.15
0.35
1988/891
212.9
23.2
79.8
176.4
304.4
139.1
935.8
472.5
90.0
1.98
0.32
        nagement, personnel, maintenance of works and equipment, disposal of sludges and domestic wastes supply of tools and
 varlTmaterials, drinking water, telephone and alarm services, insurance program, control analyt.ca. costs, and upkeep of the

 access road.
 including those set out in the table plus cleaning of the purge wells.
 'Including purchase and repair of mechanical equipment, minor modifications, and techn.cal stud.es needed for sound plant

 management.
    Lorentz Barrel and Drum Site. Table 6-6 was ex-
 tracted from an  "Applications Analysis Report"
 prepared for the  U.S.  EPA  (U.S. EPA 1990) on the
 Ultroxฎ technology.  These costs are order-of-mag-
 nitude estimates (-30 to +50 percent) as defined by the
 American  Association of Cost Engineers.  A more
 detailed explanation of the  derivation of these costs
 can be obtained from the report.  The significance of
 the utility costs as the size of the units increase should
 be noted although the relative cost per liter treated
 decreases.
     For the purpose of this economic analysis, it is as-
 sumed that the system will be operated in a continuous
 mode, 24  hours a day, 7 days a week, for one year.
  During this period, the unit should treat approximately
  40 million liters in the 75L/min unit, 200 million liters in
 the 375 L/min unit, and 500  million liters in the 950
  L/min unit. One year was chosen as the period of time
  for this analysis so that reliable annual operating and
  maintenance costs could be  determined.  Based  on
  these data, unit operating costs  were calculated and
  are presented in Table 6-6.  Numerous assumptions
  with respect to the mode of operation of the units were
  made and these are outlined in greater detail in the
  U.S. EPA report.
      Lot River.  No information was provided on the
  capital costs of the system. However, operating cost
  data were provided and are set out in Table 6-7.
6.8   Future Status of Case Study
      Processes and the Technology as a
      Whole

6.8.1  Air Stripping and Activated Carbon
   The design  of air stripping and activated carbon
processes  is highly developed and well understood.
Mathematical models exist for both processes.  The
design of processes to treat the emissions  from an air
stripper are also well developed.  However, the  Ville
Mercier experience reinforces the need for careful con-
sideration of the types of ntaminants to be treated
for successful process design and performance.
   Both unit operations can be designed by qualified
consultants. Proprietary systems are also commer-
cially available. Recently, several novel proprietary air
strippers, which  supposedly have advantages  over
packed towers, have come onto the market place.
   Areas anticipated for research and development re-
 late to more cost-effective processes for the treatment
 of air emissions from air strippers.  In part, this is ex-
 pected because of the likelihood that regulatory agen-
 cies  will not allow untreated air  emissions from air
 strippers in the future.
    Future developments may relate to the use of  more
 specific resins  for the recovery of organics from  liquid
 or gaseous streams, or to the use of membrane  tech-
 nologies,  such as pervaporation to  remove  the or-
                                                     73

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Tabla 6'6. Estimated capital and operating

Item
CAPITAL COSTS
Sito preparation costs
Permitting and regulatory costs
Capital equipment costs
Startup and fixed costs
Site demobilizing costs

Total One-Time Costs

OPERATING & MAINTENANCE COSTS
Labor costs
Supply and consumable costs
Utility costs
Effluent monitoring and disposal costs
Residuals and waste shipping, handling, and
transporting costs
Analytical costs
Equipment repair and replacement
costs

Total Annual Operation and Maintenance Costs
CALCULATED UNIT COST, US$ PER 3750L
costs associated with three Ultroxฎ system
units (in US$,
1990).
Treatment Flow Rate
75 L/min


36,000
3,500
70,000
32,000
2,000

143,500


6,600
10,500
1 2,000
3,000

1,000
24,000

4,000
61,100
5.82
375 L/min


55,000
7,500
150,000
32,000
3,000

247,500


6,600
1 6,500
58,000
3,000

5,000
24,000

22,000
135,100
2.57
950 L/min


75,000
13,000
260,000
32,000
4,000

384,000


6,600
20,800
145,000
3,000

7,000
24,000

33,000
239,400
1.82
  ganics, condense them into a small volume, and either
  purify them or destroy them using other processes.

  6.8.2 Photo-oxidation Technologies
    The Uitroxฎ technology is one example of a class of
 technologies generally called  "advanced oxidation
 processes".  A number of competing processes which
 are a variation of the Ultroxฎ technology are commer-
 cially available.   Some of these use only the oxidants
 Ha02 and Oa; others use medium pressure UV lamps
 In combination with H2O2 or O3.
    Advances will come as we  increase our under-
 standing of the process and can therefore more readily
 define optimum process operating conditions.
    Other advances are  likely to occur in the areas of
 reductag power consumption, ameliorating the effects
 of foulants, such as iron and  manganese, and combin-
 ing the process with membrane technologies to treat a
 broader mix of contaminants.
   As there are no residuals from these processes and
 when operating experience is gained  with these
 processes, the future looks promising as regulations
 with respect  to the treatment of emissions become
 more stringent.   (It should be noted, however that
there may be residuals associated with pretreatment
processes.)
 Table 6-7. Lot River operating costs (in French francs).
  Chemicals

  Handling

  Energy

  Analyses

  Maintenance

  Personnel

  TOTAL


  CALCULATED UNIT COSTS/M3**
 2,460 F/d

 600 F/d

 2,190 F/d

 260 F/d

 1,890 F/d

 2,830 F/d

 10,230 F/d

 12 to 33  F/m3


US S 2 to US$6/m3
(approx.)
 *5 French francs = approximately US$1.
"Cost is variable depending upon the flow to the plant which
  can vary from 20 to 50 m3/h.
                                                  74

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                                                                                                           1
                                                                       Pump and Treat Ground Water
6.8.3  Precipitation Technology
   This technology is readily available and can either
be designed or can be purchased as a "turnkey" pack-
age from a number of vendors.
   The technology is highly developed. Residuals in
effluents may be lowered through the use of "tertiary"
processes after clarifiers.  These generally consist of
either granular media filtration or membrane "filtration".
Both processes are commercially available.
   If sludge disposal is a serious problem, specific
resins or "adsorbents" may be used as an alternative,
thus eliminating sludge production.  However, the me-
tals must then be removed from the resins or adsor-
bents and preferably recovered, with  any chemicals
used being  recycled.  Obviously  if simply another
sludge is produced, there is no point in using this alter-
native.
REFERENCES

     Aquifer decontamination for toxic organics:  the case study of Ville Mercier, Quebec.  Final Report Vol. Ill by
     the SNC Group for the Wastewater Technology Center, December 1991.

     Goubier, R.  Vieille montagne. in: Proceedings, NATO/CCMS Fourth International Conference, Demonstra-
     tion of Remedial Action Technologies for Contaminated Land and Ground Water, Angers, France,
     1990. p. 28.

     Halevy, M., Booth, R. and Schmidt, J. Assessment of ground water treatment at Ville Mercier, Quebec, la:
     Proceedings, NATO/CCMS Third International Conference, Demonstration of Remedial Action Tech-
     nologies for Contaminated Land and Ground Water, Montreal, Canada, 1989. p. 36.

     Lewis, N., Topudurti, K. and Foster, R.  A field evaluation of the UV/oxidation technology to treat con-
     taminated ground water at a hazardous waste site, in: Proceedings, NATO/CCMS Third International
     Conference, Demonstration of Remedial Action Technologies for Contaminated Land and Ground
     Water, Montreal, Canada, 1989. p. 60.

     Mattel, R. Groundwater contamination by organic compounds in Ville Mercier:  new developments. In:
     Proceedings, NATO/CCMS Second International Conference,  Demonstration of Remedial Action Tech-
     nologies for Contaminated Land and Ground Water, Bilthoven, The Netherlands, 1988. p. 144.

     Nilsson, B. and Jakobsen, R.  The separation pumping technique, in: Proceedings, NATO/CCMS Fourth In-
     ternational Conference, Demonstration of Remedial Action Technologies for Contaminated Land and
     Ground Water, Angers, France, 1990. p. 48.

     Proceedings: A symposium on advanced oxidation processes for the treatment of contaminated water and
     air. Toronto, Canada. June 4 and 5,1990.  Environment Canada, Wastewater Technology Center
     Burlington, Ontario.

     Schmidt, J.  Aquifer decontamination for toxic organics, Ville Mercier,  Quebec, Csinada.  In: Proceedings,
     NATO/CCMS First International Workshop, Demonstration of Remedial Action Technologies for Con-
    taminated Land and Ground Water, Karlsruhe, Germany, 1987. p. 51.

    Simard, G. and Lanctot, J.P. Decontamination of Ville Mercier aquifer for toxic organics.  in:  Proceedings,
     NATO/CCMS First International Meeting, Demonstration of Remedial Action Technologies for Con-
    taminated Land and Ground Water, Washington, D.C., U.S.A.,  1987.  p. 135.

    Technology Evaluation Report. SITE program demonstration of the Ultroxฎ international ultraviolet radia-
    tion/oxidation technology. Prepared for Risk Reduction Engineering Laboratory, ORD, U.S. Environ-
    mental Protection Agency, Cincinnati, Ohio, April, 1990.

    U.S. EPA. Ultraviolet radiation/oxidation technology.  Applications Analysis Report. EPA/540/A5-89/012,
    U.S. Environmental Protection Agency, Cincinnati, Ohio, 1990. 69 pp.
                                               75

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 Chemical Treatment of Contaminated Soiis: APEG

 Michael A. Smith
 Clayton Environmental Consultants, Ltd.
 68 Bridgewater Road, Berkhamsted, Hertfordshire HP4 1JB
 United Kingdom
ABSTRACT

   The conversion of halogenated compounds (particularly PCB's) in contaminated soils into far less harmful
products may be carried out using an alkaline metal hydroxide with polyethylene glycol (APEG). Processes of this
type are applicable to soils and soil-like materials (after excavation) contaminated with either aromatic or aliphatic
chlorinated organic compounds; the latter require more rigorous treatment conditions.
   In general terms, the reagent (APEG) dehalogenates the pollutant to form a gylcol ether and/or a hydroxylated
compound and an alkali metal chloride which are water soluble. There are many variants of the general process,
many covered  by patents etc. The most widely used version uses potassium hydroxide in combination with
polyethylene glycol to form a polymeric alkoxide anion referred to as KPEG. The end products of the technology are
regarded as nontoxic and having minimal environmental impact.
7.1   Introduction
   This chapter is about the chemical treatment, or
dehalogenation, of soils contaminated with chlorinated
organic compounds, using an alkaline metal hydroxide
with polyethylene glycol (APEG). A schematic draw-
ing of an APEG  application is shown in Figure 7-1.
The soil is screened to remove debris and large ob-
jects, homogenized, and reduced in size to allow treat-
ment in the reactor without the soil binding to the mixer
blades and to permit close contact of the contaminants
with the reagents. Because water inhibits the reaction,
it may be necessary to dry the soil before treatment.
   Typically  the reagents are mixed thoroughly with
the contaminated soil in a reactor which is heated to
100 to 180 ฐC (the range 25-150 ฐC has also been
quoted (U.S. EPA 1989b). The reaction proceeds for 1
to 5 hours depending upon the type, quantity and con-
centration of the  contaminants.  The treated material
goes from the reactor to a separator where the reagent
is removed and can be recycled.
   During the reaction, water vaporizing from the reac-
tor is condensed and collected for further treatment or
recycling through the washing process, if required.
Carbon filters are used to trap any volatile organics
that are not condensed.  The soil is washed with water
to remove residual reagents and products,  and
neutralized by the addition of acid. It is then dewatered
before disposal. The treated soil may be returned to
beneficial  use with appropriate amendment with fer-
tilizers etc.

7.1.1  Applicability
   APEG processes are applicable to contaminants in
soils,  sludges, sediments and oils.  These processes
are mainly used  to treat chlorinated aromatic or
aliphatic organics  such  as polychlorinated  biphenyls
(PCB's), polychlorinated clibenzo-p-dioxins (PCDD),
polychlorinated   dibenzofurans   (PCDF's),
polychlorinated terphenyls (PCTP's), chlorobenzenes,
and some halogenated pesticides and herbicides.
   The concentrations of PCB's treated are reported
to be  as  high as  45000 mg/kg (4.5 percent); con-
centrations in this  case were reduced to less than 2
mg/kg per individual PCB congener (U.S. EPA  1990).
However, there  are reported to be limitations  to the

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Chapter?

• Waste Treatment •
141

^ •ฐM". 	 	

Soils and ^pp—^c 7<•
>. ป*"ป. X"V .4 tf-^^
Wll*rl * l**^
r|
ES Wasn Water ^/ ^ wisri WnMDf '
Reactor ฃ to Recyao ^ ฃ to Rปcyaซ J

Now •oaoCMd Iron GMBQO Rซm*dtfbon Carp, Icr Booz. Aปซo A Hamilton Inc

Figure 7-1. Schematic diagram of a typical glycol dehalogenation treatment facility.
process with regards to lower weight Arociors; DMSO-
based processes may not work on Aroclor  1240 for
example (see below).Polychlorinated dibenzo-p-
dioxins (PCCD's - "dioxins") and poiychlorinated
dibenzofurans (PCDF's - "furans") have been treated
to nondetectable levels at ng/kg (parts per trillion) sen-
sitivity (U.S. EPA 1990).
   APEG technology, preferably using the reagent
KTEG (potassium  tetraethylene  glycol), will
dehalogenate aliphatic compounds  but higher
temperatures and longer reaction times are  required
than for aromatic compounds.

7.1.2 Variations on the APEG Process
   The most widely used variant  of the process uses
potassium hydroxide  (KOH) with polyethylene  glycol
(PEG) to form a polymeric alkoxide anion, referred to
as KPEG. This acts as an effective nucleophile and as
a phase-transfer catalyst (Komel and Rogers 1985).
The presence of oxygen is an essential requirement of
the process.  The reactions involved are shown
schematically in Figure 7-2.
   In some KPEG reagent formulations  to treat
chlorinated  aromatics, dimethyl sulfoxide  (DMSO) is
added to reduce the reaction time. Sofolane (SFLN -
tetrahydrothiophene) may also be used to accelerate
the reaction.
   Although potassium hydroxide has been the most
widely used reagent, sodium hydroxide has been used
In the past and may be used increasingly in the future
because of lower costs. Other possibilities include
combinations of potassium or sodium hydroxides with
tetraethylene glycol (ATEG).
   Proprietary variations include the "APEG-PLUS"
treatment  system which uses potassium hydroxide
with DMSO marketed by the Galson Remediation Cor-
poration and one offered by SDTX Technologies Inc
who  own the Fuller Institute patents  (e.g. Pytlewski
andKrevitz 1983).
   The United States Environmental Protection Agen-
cy (U.S. EPA) has devoted effort to the development of
KTEG (potassium tetraethylene glycol) processes for
the treatment of halogenated aliphatic compounds
(Kernel and Rogers 1985; Harden and Ramsay 1986;
Rogers and Kernel 1987).   When  KTEG is used, a
dehydrohalogenation  reaction occurs. Halogenated
compounds with one carbon atom react to form carbon
dioxide and potassium halide. Compounds containing
more than one carbon react to form acetylene (Rogers
and Kernel 1987; Harden and Ramsay 1986). KTEG
has been shown on a laboratory scale to work with
compounds such as ethylene dibromide, carbon
tetrachloride, ethylene dichloride, chloroform and
dichloromethane  (Harden and Ramsay 1986; Rogers
and Kernel 1987).

7.1.3 Operational Requirements
   Land is required for the operating plant, and for the
safe and secure storage of reagents, soil to be treated,
oversize material  prior to crushing or disposal, and for
treated soil pending certification that treatment has
been;effective.
                                                78

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                                               Chemical Treatment of Contaminated Soils: APEG
          HO-PEG +  KOH   	

          Aryl-ci + KO-PEG

          Aryl-0-PEG  	
	>   KO-PEG   -f H2O	(1)

  	>  Aryl-O-PEG +  KC1  ....(2)

•> Aryl-OH +  Vinyl-PEG	(3)
    Note: In reaction  (1)  the  polyethylene glycol  (PEG) is reacted
    with potassium hydroxide to form  the reactive  KPEG species.  This
    preparative step may be performed directly in  the contaminated
    matrix  or externally.  Reaction (2)  takes place takes  place over a
    wide temperature range from ambient to about HOC.  Reaction  (3)
    represents  the conversion  of the  ether linked  PEG/Aryl moeity to
    a phenolic  with consequent release of  a vinyl  terminal
    polyethylene glycol.

    Equation (4)  below represents  this overall reaction.
       R-(C1)_+ A-PEG
-OR1
                       AC1
 Figure 7-2. APEG reactions.
   A supply of water is required. Energy is required to
dry the materials to be treated, heat the reaction ves-
sel, and to dry the treated materials. Electric power
and a steam generating plant will be required; accord-
ing to the U.S. EPA (U.S. EPA 1989b), a full-scale
dehalogenation plant with a batch capacity of 60 m3
(80 yd3)  requires  an  average of 670 kilowatts, (U.S.
EPA 1989b). Such a plant might be expected to treat
120-150 m3 (160-200 yd3) in one working day.
   On-site analytical facilities, including extraction
equipment and  gas  chromatography/mass
spectrometry, are  required to monitor inputs and out-
puts from the process. Perimeter air monitoring may
be required.
   Contaminated  soils and reagents are hazardous
and a safety plan is required to ensure personnel
safety, safety in plant  operation, and to protect.the en-
vironment.

7.2  Case Study Chosen
   Only  one case  study  was  included  in the
NATO/CCMS Pilot study: the U.S. EPA's SITE (Super-
fund  Innovative Technology  Evaluation) Demonstra-
tion at Wide Beach, New York (U.S. EPA 1989a; U.S
EPA  1991b; U.S.  EPA 1991 a). This involved applica-
tion of a KPEG process to the treatment of PCB-con-
              taminated soils in combination with a complex four-
              stage "thermal processor".

              7.2.1 Background
                The Wide Beach site is located in a residential area
              south of Buffalo, New York. From 1968-1978, PCB
              (Aroclor 1264) contaminated waste oil was used for
              dust control on local roads at Wide  Beach. About
              155,000 liters of oil were applied.  Following installa-
              tion of a sewer in 1980,  excavated contaminated soil
              was used as fill in residential gardens (yards) and a
              community recreation area.
                Soil contamination in the area ranged from 0,18 to
              1026 mg/kg in samples collected from residential
              driveways, roadways and drainage ditches. PCB con-
              centrations in excess  of 10 mg/kg were detected at
              depths of up to 1 meter in the soil in drainage ditches;
              in general, these concentrations reached only to about
              0.15 to  0.3 meters in depth.  It was estimated that
              21,700 tonnes (15-16,000 m3) of soil were con-
              taminated; about 43,000 tonnes of soil were actually
              processed.
                A cleanup target of not more than 2 mg/kg was set
              (U.S. EPA 1989a; AOSTRA 1990).
                                           79

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Chapter?
7.2.2 The KPEG Demonstration Project
   The remedial action at Wide Beach consisted of:
   • Excavating soils with PCB concentrations greater
     than 10 mg/kg from all areas

   • Excavating contaminated asphalt material from
     roadways for disposal off-site, with uncon-
     taminated material being retained for reuse

   • Treating  the  PCB contaminated soils in a con-
     tinuous process using an  Anaerobic Thermal
     Processor (ATP) in  association with a KPEG
     process

   • Using the cleaned soil as fill in excavated areas

   ป Repaving the roadways and driveways

   ซ Treating  perched water in the sewer trench (this
     water has been found to contain up to 10 ng/l
     PCB's).

   Afterthe work was completed, the residences were
thoroughly cleaned to remove any stray dust, etc.
(See Figure 7-3 for the overall flow of materials.  See
Appendix 7-A for a more detailed discussion of  the
process.)

7.3   Performance Results
   The continuous-processing ATP  technology was
demonstrated in May 1991. Key  findings of the
demonstration were:
   ซ The ATP unit removed PCB's in the contaminated
     soil to levels below  the desired  cleanup con-
     centration of  2 mg/kg. PCB  concentrations were
     reduced  from an average concentration of 28.2
     mg/kg in the contaminated feed soil to an average
     concentration of 0.043 mg/kg in the treated soil.

   ซ The ATP does not appear to create dioxins and/or
     furans.

   ป No volatile or semivolatile organic degradation
     products  were detected in the treated soil. There
     were also no leachable VOC's or SVOC's
     detected  in the treated soil.

   • No operational problems affecting the ATP's
     ability to treat the contaminated  soil were ob-
     served.
7.4   Residuals and Emissions
   There are three main process streams: the treated
soil, the wash water and, possibly, air emissions.
   The treated soil will need to be analyzed to deter-
mine if it meets treatment objectives and/or regulatory
requirements for disposal or re-use. The soil's acidity
must be adjusted to a suitable value before disposal or
reuse.
   Research by the U.S.  EPA has shown the  by-
product compounds to be neither toxic nor otherwise of
concern (see for example Komel and Rogers 1985).
However this will only be the  case if the process is
carried out properly and dechlorination is complete. If
full dechlorination is  not  achieved, toxic residual
materials may remain (see Limitations below).
   Waste wash water  should contain  only trace
amounts of contaminants and reagents, and should
meet appropriate discharge standards enabling it to be
disposed to public sewer or surface water, subject to
the usual licensing and regulatory requirements.

7.5   Limitations
   Factors limiting the effectiveness of glycolate treat-
ment include highly concentrated contaminants
(greater than 5 percent), high  water content (greater
than 15 percent), low pH (less than 2.0),  high humic
content (soil), and the presence of alkaline-reactive
materials (e.g., aluminium or other metals).

7.5.1  Inherent in the Technology
   Although shown to be effective for a wide range of
chlorinated hydrocarbons in a range of media, there
are limitations to its effectiveness with regard to certain
compounds such as lighterweight Aroclors (e.g., 1240,
1242)  and hexachlorobenzene.  This has  been at-
tributed, at least in the case of the latter (Rogers et al.
1991),  to steric hindrance caused by the bulky nature
of the  attacking nucleophilic  reagent, polyethylene
glycoxide.
   The apparent lack of  information on the long term
stability of the resulting products in the soil environ-
ment may also  be limiting in  some applications  be-
cause  it may be considered that the initial nontoxic
nature  of the reaction products can not be guaranteed
to last.
   These potential difficulties appear to be overcome
in the combined thermal and KPEG treatment used at
Wide Beach which appears  to result in complete
destruction of PCB's through combined chemical and
thermal action.

7.5.2  Health and Safety
   Treatment of certain chlorinated  aliphatics in high
concentrations with APEG  may produce compounds
that are potentially explosive (e.g. chloroacetlylenes)
and/or cause a fire hazard.  The use of DMSO or
similar reagents may result in the formation of highly
flammable volatile organics (e.g., methyl  sulphide).
Alkaline reactive materials such as aluminium can
result in formation of hydrogen. Vapors from heating
oily soils, which are often the  matrix in which PCB's
are found, can also create such potential problems as
                                                 80

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    Chemical Treatment of Contaminated Soils: APEG
                               a  i
                                              a>
                                              .2
                                              •s

                                              (0

                                              I
                                              TJ

                                              •g
                                              O
                                              OQ
81

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Chapter?
fires and noxious fumes.  These potential  problems
can all be overcome by appropriate  process design.
The process must also be conducted with care be-
cause of the elevated temperatures and production of
steam, the use of caustics in the process, and the
acids used in neutralization. If DMSO is used, care
must be taken to prevent contact of DMSO with skin.  It
is a powerful solvent and skin penetrant, and enhan-
ces transport of PCB's through the skin, thus increas-
ing the risk of  exposure.  KTEG  processes are
exothermic and can produce vinyl halides as inter-
mediate compounds. Special considerations will there-
fore apply in the design of plants to operate these
processes (Harden and Ramsay 1986).

7.6   Costs
   In September 1990 US$, costs were put at $220-
550/tonne ($200-500/short ton).
   One vendor quoted the average cost of treatability
studies as US$2000-3000 depending  on the chemistry
of the target contaminant(s). Treatment costs were es-
timated to be $130-390/m3 ($100-$300/yd3) depending
on site-specific factors (U.S. EPA 1989b).
   Costs at the Wide Beach demonstration site had
been estimated (U.S. EPA 1989a) as likely to be about
$6,000,000 to treat about 15,000 m3 (20,000 yd3) of
soil to achieve a level not greater than 2 mg/kg, i.e.,
about $390/m3 ($300/yd3). In practice, the contract
value for the work was $15,500,000. Information on
the details of this value is not available, nor is informa-
tion on the cost  of treating the larger than  expected
volume of soil (23,000 m3) that was actually treated.

7.7   Factors to Consider for Determining
      Applicability of the Technology
   Studies on materials to be treated should include
determination of the nature and quantities of individual
organic compounds present,  and investigation of the
presence of moisture, alkaline metals, organic matter
content (humic content), clay content, glycol extrac-
tables content, presence of "multiple phases" and total
organic  halides, and other factors that have the poten-
tial to affect processing times, effectiveness and costs.
The major difficulty is devising means to reduce
processing times sufficiently to permit practical treat-
ments to be effected.
   Laboratory treatment studies should be carried out
to determine optimum operating factors such as type
and quantity of reagent to use, temperature and treat-
ment time.

7.8   Future Status of the Technology
   The  KPEG technology demonstrated in Wide
Beach has been selected for application for treatment
of soils and sediments containing 500 to 500,000
mg/kg PCB's at Waukegan Harbour north of Chicago
(de Percin 1991).
   Batch processes of this type have also been shown
to be effective in terms of reducing contaminant levels
to acceptable concentrations in a number of applica-
tions (for example see Peterson 1990).
   Variants of the process are available from a num-
ber of vendors. It is expected that work will continue to
incorporate the dechlorination process with other treat-
ment steps to ensure effective application to a range of
contaminants and media. In addition, it is expected
that efforts will be made to overcome the limitations to
effectiveness mentioned above.
   It should be noted however, that competitor tech-
nologies are being developed. One process  in par-
ticular is catalytic transfer hydrogenation (Rogers et al.
1991) in which hydrogen is the reacting nucleophile.  It
is claimed that this process overcomes the problems of
steric hindrance associated with the use polyethylene
gylcol, and is thus  capable of bringing  about total
dechlorination with  formation of non-toxic reaction
products.
   In contrast, reports that quick lime might be an ef-
fective treatment agent for PCB's  have been shown
not to be true (U.S. EPA 1991 c; Sedlaket al. 1991).
REFERENCES
     AOSTRA Taciuk processor performing soil cleanup. The TARpaper, Vol.13, No.4,1990.

     de Percin, P. SITE demonstration of the TACIUK thermal desorption process at the Outboard Marine Corp.,
     Waukegan Harbour, Illinois Site, 1991.  Appendix 7-D to this report.

     Harden, J. M. and Ramsay, G. C. Catalytic dehydrohalogenation: A chemical destruction method for
     halogenated organics.  EPA/600/2-86/113, U.S. Environmental Protection Agency, Cincinnati, 1986.

     Heller, H. Poultice method for extracting hazardous spills. U.S. Patent 4483716,1984.

     Komel, A. and Rogers, C.  PCB destruction: a novel dehalogenation reagent. IQ: Journal of Hazardous
     Materials, 12,161-176,1985.

     Peterson, R. L. Methods for decontaminating soil.  U.S. Patent 4447541, 1984.
                                                 82

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                                                Chemical Treatment of Contaminated Soils: APEG
 Peterson, R. L. Method for reducing content of halogenated aromatics in hydrocarbon solutions. U.S.
 Patent 4530228, 1985.

 Peterson, R. L. Method for decontaminating soil. U.S. Patent 4574013,1986.

 Peterson, R. L. APEG-Plus™: dechlorination of soils and sludges. In: Proceedings of the Symposium Haz-
 ardous Waste Treatment: Treatment of Contaminated Soils, Cincinnati, Ohio, (Air & Waste Manage-
 ment Association, Pittsburgh 1990) pp. 94-99,1990.

 Pytlewski, L. L. and Krevitz, K. Method for decomposition of halogenated organic compounds  U S  Patent
 4400552,1983.

 Rogers, C. J. and Kernel, A. Chemical destruction of halogenated aliphatic hydrocarbons.  U S Patent
 4675464, 1987.                                                              :

 Rogers, C. J., Kernel, A. and Sparks, H. L. Base catalyzed decomposition of toxic and hazardous chemi-
 cals. U.S. Environmental Protection Agency, Cincinnati, 1991.

 Sedlak, D. L., Dean K. E., Armstrong, D. E., and Andren, A. W. Interaction of quicklime with
 polychlorobiphenyl-contaminated solids, in: Environmental Science and Technology, Vol 25 No 11
 1936-1940,1991.                                                                        '

 Taciuk, W. The AOSTRA-TACIUK thermal pyrolysis/desorption process, 1991.  Appendix 7-B to this report.

 Taciuk, W. and Ritcey, R. M. PCB decontamination of soils and sludges with the Taciuk process. In:
 Proceedings HAZTECH CANADA, 4th Annual Environmental Conference, Calgary, 1991.

 U.S. EPA. Chemical on-site treatment utilizing KPEG process at Wide Beach, New York.  Emergency
 Response Division, U.S. Environmental Protection Agency, November 1989.

 U.S. EPA. Innovative technology: glycolate dehalogenation.  U.S. Environmental Protection Agency, Direc-
tive 9200.5-245S, 1989.

 U.S. EPA. Chemical dehalogenation treatment,  in: APEG Treatment. U.S. EPA Engineering Bulletin
 EPA/540/2-90/015. U.S. Environmental Protection  Agency, 1990.
 U.S. EPA. Demonstration plan for the Taciuk Thermal Processor at the Wide Beach development site:
 Demonstration Program Draft Report, U.S. Environmental Protection Agency. March 1991.

U.S. EPA. AOSTRA-SoilTech anaerobic thermal processor treats PCBs in soils at Wide Beach develop-
ment Superfund site in Brant, New York. U.S. Environmental Protection Agency, Cincinnati.  1991.

U.S. EPA. Fate of polychlorinated biphenyls (PCB's) in soil following stabilization with quicklime.
EPA/600/2-91/052, U.S. Environmental Protection Agency Office of Research and Development
Washington DC, 1991.
                                           83

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                                                                                                8
 Microbial Treatment Technologies
 SjefStaps
 Grontmij nv
 P.O. Box 203, 3730 AE De Bilt
 The Netherlands
 ABSTRACT

   A large number of organic contaminants can be degraded by microorganisms.  The compounds can vary from
 easily degradable compounds like monocyclic aromatics to more xenobiotic compounds like chlorinated aliphatics.
   Basically,  biological soil  remediation techniques can be divided into three groujps:  in situ biodegradation,
 landfarming and composting, bioreactors.
   An advantage of biological treatment is its cost-effectiveness.  On the other hand, the treatment period is relatively
 long, ranging from a few weeks for composting up to a few weeks to several years for in situ biorestoration. Also,
 when treating soil biologically, it is typical that, depending  on  the type of soil and contaminant, some residual
 concentrations will remain after treatment. It has to be determined whether these low residual concentrations can
 be regarded as safe.
   Given the high level of international research in microbial treatment, it is expected that the scope of application
 will be broadened in the coming years.
   This NATO/CCMS Pilot Study included five case study reports regarding microbial treatment. In addition, as a
 NATO/CCMS Fellowship project, the study "International evaluation of in situ biorestoration of contaminated soil and
 ground water" was conducted. These studies are discussed in this chapter.
8.1   Introduction
   A large number of organic contaminants can be
degraded by microorganisms. The compounds can
vary from easily degradable  compounds like
monocyclic aromatics (e.g., benzene) to  more
xenobiotic compounds (e.g., trichloroethylene, a
halogenated hydrocarbon).
   Biological treatment techniques for contaminated
soil and ground water aim at optimizing conditions for
promoting biodegradation  of organic compounds
therein. These factors are related to characteristics of
the chemical compound, soil, and the indigenous
population of microorganisms.
   The chemical compound and its degradation path-
way are decisive for the environmental characteristics
to be chosen. For example, an aerobic environment
should be chosen in the case of nonhalogenated con-
taminants, and an anaerobic environment should be
chosen in most cases of halogenated contaminants,
since the fastest degradation occurs under these con-
ditions.
   The purpose of biological treatment is the degrada-
tion of contaminants to harmless intermediates  and
end products to such a degree that the remaining con-
centrations of contaminants and degradation products
are below the applicable standard. The ultimate goal is
to reach complete mineralization of the contaminants,
that is, degradation into CO;> and HaO.
   Basically, biological soil  remediation techniques
can be divided into three groups:
   • In situ biodegradation
   • Landfarming and composting

-------
Chapter 8
   • Bioreactors.

   The first technique is applied In situ; the latter two
are applied on- or off-site.
   In situ biodegradation of soil and ground water aims
at the stimulation of the biological degradation of con-
taminants in the subsurface environment. Usually a
recirculation system for ground water is installed. Con-
taminated ground water is treated above ground, after
which oxygen and, if necessary, nutrients are added to
the water that infiltrates the soil, in order to stimulate
the indigenous microorganisms to  degrade con-
taminants. The ground water treatment can consist of
an air stripper for volatile contaminants or a biological
treatment for dissolved contaminants.
   Also, activated carbon filters are often used. Con-
taminants in the exhaust air from an air stripper can be
removed by means of activated carbon or a biofilter
with compost.
   In addition to In situ biorestoration by means of
recirculation of water,  venting can be applied in order
to stimulate the indigenous microorganisms to degrade
contaminants and to remove volatile contaminants in
the unsaturated zone.
   With landfarming, contaminated soil is spread out
over a certain land surface up to a thickness of about
0.40-0.60 meters. If necessary, nutrients are added.
Regularly, the soil  is mixed by means of agricultural
implements  in order to increase  the biological
degradation.
   Composting is a treatment similar to landfarming.
However, the soil is placed  on heaps and materials
such as wood chips or compost are usually added to
facilitate the oxygen distribution through the heaps.
   Bioreactors are used to treat more recalcitrant com-
pounds, such as polynuclear aromatic hydrocarbons
(PAH's). A soil-water(-air) system is used, in  which
several  environmental factors can be controlled and
maximized for optimal  degradation.

8.2  Case Studies Chosen
   The  NATO/CCMS  Pilot Study included five case
studies regarding both in situ and  on- or off-site
microbial treatment technologies.  In addition  to these
case studies,  a NATO/CCMS Fellowship project under
the Pilot Study was conducted:  "International evalua-
tion of in situ biorestoration of contaminated  soil and
ground water (Staps 1990)." In this Fellowship project,
21  in situ biorestoration projects in The Netherlands,
Germany, and the United States were visited and
evaluated. Because of the evaluating character of the
Fellowship project, its  results run through the "in situ"
part of this chapter as a continuous thread.
   A short description of the case studies  is given
below.  Longer discussions are included in Appendix
8.
8.2.1     In Situ Projects

8.2.1.1   Case Study 8-A: Aerobic/Anaerobic In Situ
         Degradation of Soil and Ground Water,
         Skrydstrup, Denmark
   The purpose  of the project was to verify whether
full-scale cleanup of ground water is possible using in
situ biodegradation of chlorinated solvents.
   Four separate research approaches to biorestora-
tion have been initiated:
   • Biodegradation of  chlorinated  solvents in con-
    taminated soil

   • Aerobic biodegradation of chlorinated solvents by
    addition of methane

   • Aerobic biodegradation of chlorinated solvents in
    the unsaturated zone by co-metabolism by oxida-
    tion of methane and/or propane gas

   • Anaerobic biodegradation of chlorinated solvents
    in the contaminated zone by addition of sodium
    acetate.

8.2.1.2   Case Study 8-B: In Situ Biorestoration of Soil,
         Asten,  The Netherlands
   The objective of this research and demonstration
project is to study the technical and financial feasibility
of in situ biorestoration of a subsurface soil con-
taminated with oily substances. The approach of the
project started from a literature study (1983) and
laboratory research, continued with column studies,
and is ending up with a full-scale cleanup (started in
1990). Field data are currently  not available. A
simplified schematic is shown in Figure 8-1.

8.2.1.3   Case Study 8-C: In Situ Enhanced Aerobic
         Restoration of Soil and Ground Water,
         Eglin Air Force Base (AFB), United States
   The project includes a full-scale biodegradation re-
search project at a  JP-4 jet fuel spill site on Eglin AFB
near Ft. Walton Beach, Florida, United States. A treat-
ment system was designed to compare the operational
benefits and limitations of the following three hydrogen
peroxide/nutrient application methods:
   • Injection wells
   • Infiltration galleries
   • Spray irrigation.

   Figure 8-2 shows the system flow diagram.

8.2.2     Ex Situ Projects

8.2.2.1   Case Study 3-D: Biological Pre-treatment of
         Ground Water, Bunschoten, The Nether-
         lands
   The subject of this project is the pretreatment of
ground  water  contaminated with hexachloro-
                                                  86

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                                                                      Microblal Treatment Technologies
             IN SITU BIORESTORATION OF A SUBSOIL
                                                                       stripping
                                                                    1000-2000
                                                                    >2000
                                                                    100 - 1000
                                                                    (mg gasolinei/kg)
                                                                                      discharge
Figure 8-1. Cross-section of the soil with an overview of the restoration process.
cyclohexane (HCH, a pesticide), chlorobenzene, and
benzene. The project concerns some small-scale ex-
periments with a trickling filter and a rotating biological
contactor. A simplified schematic is shown in Figure
8-3.  The applied method is based on the following four
main processes:
   • Washing of contaminants from the soil by  en-
    hanced recirculation of purified water

   • Purification of the pumped-up water by reverse
    osmosis (RO)

   • Biological purification of the concentrate of  RO
    (without inoculation)

,   • In situ biodegradation of contaminants in the soil.
;    The present concept will be tested in a large-scale
    pilot project in The Netherlands.
8.2.2.2  Case Study 8-E: notary Composting Reactor
         for Oily Soils, Soest, The Netherlands
   This biological treatment method was developed for
off-site decontamination of  oil-contaminated soil at
field capacity. First, laboratory-scale studies were car-
ried out in order to determine the optimum  environ-
mental conditions for oil degradation. Then the
(research) project  was carried out at a former
municipal solid waste composting installation. The soil
was treated in the rotating bio reactor, in which the soil
temperature, oxygen, moisture, and nutrient levels can
be adjusted. A  schematic of the biological treatment
process in  the rotating bioreactor is shown in Figure
8-4.
                                                  87

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Chapter 8
                                               ,';
ABQVEGROUWJ
                               J
                               U
                                                        FREE PRODUCT
                                                          INFLUENCE
                                                                                       \
                                                                                         \
                                                 9     20
                                                      reet
                                                         O  RECOVERY MEU.
                                                          ซ  HONITORING VCLL
                                                         ^  EJECTION WELL
Figure 8-2. Eglln AFB Site profile.
8.3   Background of the Case Study Sites
      as a Group
   When regarding the group of case study sites, it is
evident that there is considerable heterogeneity. For
example, the contamination sources include a chemi-
cal waste disposal site, a (former) gas and kerosene
station, and a pesticide production facility. A municipal
composting installation was also studied in relation to
biodegradation.
   These sources were  responsible  for the following
range of contaminants:
   • CWorinated solvents
   • Petrol
   • JP-4 (an aviation fuel)
   ป Hexachlorocyclohexane (HCH, a pesticide) in dif-
    ferent forms
   ซ Diesel oil.
                                   These contaminants are typical of the compounds
                                that generally can be biologically  degraded. They
                                range from the easily degradable petrol to the more
                                recalcitrant chlorinated compounds.  Typically, the in-
                                dividual projects have to deal with a specific group of
                                contaminants like mono-aromatic hydrocarbons,
                                polynuclear  aromatic  hydrocarbons, or chlorinated
                                hydrocarbons. Each of these groups has its own re-
                                quirements for degradation.
                                   Another example of the diversity of the project sites
                                is that some required the treatment of soil, some of
                                ground water, and some of both soil and ground water.
                                Biodegradation was applied within the projects as fol-
                                lows:
                                   • In situ treatment of both soil and ground water (in
                                    combination with  on-site biological and chemi-
                                    cal/physical treatment).

                                   • On-site treatment of the ground water (both with
                                    and without physical/chemical treatment).     :
                                                 88

-------
                                                                    MIcroblall Treatment Technologies
   • On-site treatment of the soil (after excavation).

   In two cases, the treatment was combined with ex-
cavation; in one case the waste from a chemical waste
disposal site was excavated, after which in situ bio res-
toration of the ground water was applied. In a second
case, the soil was  biologically treated on site after
being excavated.
8.4   Performance Results
   In general, degradation results were assessed in
relation to the original site concentrations  of the con-
taminants (percent degradation). In order to get insight
into the risks of the intermediate or residual concentra-
tions, standards  like  the Dutch Examination
Framework for Soil  Pollutants were used in several
projects.
           from raw water basin
                                                                                to raw water basin
                                     RBC's
 Figure 8-3. Flow diagram of the RBCs and compost filters.
 Figure 8-4. Biological treatment process in the rotating bioreactor.
                                                   89

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 Chapter 8
    Different countries require widely varying clean-up
 standards. For example, a project in The Netherlands
 started with a concentration level of mineral oil in the
 soil that in Germany is regarded to be a sufficient level
 of reclamation.

 8.4.1     Common Effectiveness of Process Units

 IN SITU BIORESTORATION
    In situ biorestoration can technologically and finan-
 cially compete with other technologies when it is  ap-
 plied at a suitable location and the process is well run.
 The remediation time can vary between a couple of
 months and several years, and is largely dependent on
 the initial concentrations, the kind of contaminants,  the
 soil structure, and the cleanup requirements.
    In The Netherlands,  an Examination Framework for
 soil pollutants  has been set up. In this Framework,
 three different indicative values can be distinguished:
    * A - Reference value
    ป B - Indicative value for further investigation
    ป C - Indicative value for cleaning up.

    In principle, the A-value must be reached when
 cleaning contaminated soils in The Netherlands.
 Residual concentrations below B-level, or even un-
 detectable levels, have been reached with  in situ
 biorestoration in projects for petrol, kerosene, diesel
 oil,  fuel oil, mineral oil, and certain chlorinated
 hydrocarbons (e.g., 4-chloro-2-methylphenol)  (Staps
 1990).
   In situ blodegradatlon of contaminated ground
 water (Case Study 8-A). Laboratory tests showed that
 tetra-chioroethylene (PCE),  trichloroethylene  (TCE)
 and 1,1,1-trichIoroethane (TCA) in sewage sludge can
 be degraded under anaerobic conditions. Lower
 chlorinated compounds are formed.
   It was not possible to achieve anaerobic degrada-
 tion of PCE, TCE or TCA in laboratory tests on sedi-
 ment from the Skrydstrup aquifer.  This might be due
 to the fact  that there  has not been a  restricted
 anaerobic environment in the upper part of the aquifer.
 It  was possible to build up a methane-oxidizing
 blomass which was able to  degrade TCE and 1,1,1-
 TCA, but not PCE.
   The ground water at  Skrydstrup contains high con-
 centrations of chlorinated aliphatics. Therefore, the
 toxicHy of 1,1,1-TCA and TCE towards a mixed culture
 of methane-oxidizing bacteria was examined in batch
 experiments. The consumption  of methane was  in-
 hibited, even by small concentrations of 1,1,1 -TCA and
 TCE. A total inhibition of the methane consumption
was observed at a TCE concentration of  13  mg/L,
whereas a total inhibition was not observed at a 1,1,1-
TCA concentration of 103 mg/L.  Experiments also
 showed that the presence of methane inhibited the
degradation of TCE.
    Accumulation   of  dichloroethanes   and
 dichloroethenes was observed in the leachate from the
 two sites of excavated soil from Skrydstrup, showing
 that anaerobic biodegradation had occurred at  both
 sites.  A significant amount of the contaminants  from
 both sites has been removed, but it could not be deter-
 mined how much had been  removed by biodegrada-
 tion and how much had been removed by other
 processes, such as stripping.
    A pilot plant for aerobic on-site biodegradation of
 chlorinated aliphatics in ground water has been estab-
 lished at Skrydstrup. The plant was operated with dif-
 ferent hydraulic retention times, in order to optimize
 the degradation of the chlorinated aliphatics.  It  was
 possible to obtain degradation of TCE of 40 percent
 with a hydraulic residence time of 3.5 hours.  At the
 same time, a methane consumption of 85 percent was
 observed. Degradation of TCA did not occur. About 10
 percent of 1,1,1-TCA and TCE were stripped.  The
 plant  was operated with alternating addition of
 methane to avoid competition between methane and
 chlorinated aliphatics, but it did not result in  an in-
 creased degradation of TCE.

 EX SITU BIODEGRADATION
    Rotating  biological contactor for  biodegrada-
 tion of HCH  in ground water (Case Study 8-D).
 Over 90  percent removal of HCH,  benzene,  and
 chlorobenzene in the  rotating  biological contactor
 (RBC) can be attributed to biodegradation. Volatiliza-
 tion and adsorption onto the sludge  are of minor  impor-
 tance to the total  removal. aHCH and •yHCH show a
 degradation rate of up to 70 percent. 8HCH shows  little
 breakdown, while  eHCH  and  (3HCH concentrations in
 the RBC remain constant. The mineralization of con-
 taminants is  complete;  there were no metabolites
 found  with gas chromatography/mass spectroscopy
 analysis.
   Rotary composting bioreactor (Case Study 8-E).
 The production-scale trials of the  rotary composting
 bioreactor indicate that,  at a soil temperature  of ap-
 proximately 22 ฐC, the  oil can  be degraded.   This
 process starts with concentrations up to 6000 mg oil/kg
 dry soil, and drops within one week to a residual con-
 centration, varying from less than 50 to 350 mg/kg dry
 soil. In this process, the greatest microbial activity oc-
 curs in the first 3-4 days. In processes  where other
 circumstances are present (temperature,  oxygen con-
tent, humidity), results will be different.
   Compost filter.  Compost filters can be  used to
treat off-gas, mainly from air strippers that are used to
 remove volatile components from ground water on
site. The  system is based on adsorption of the con-
taminants on compost material, followed by
biodegradation by  microorganisms.  Generally, perfor-
mances of compost filters for treatment of air  show
poor results (i.e., approximately 70 percent for a  broad
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                                                                       Microbial Treatment Technologies
  range of compounds). This is regardless of whether
  there is a mixture of compounds or an individual com-
  pound present.

  8.4.2    Effectiveness of the Rotating Composting
          Bioreactor on Diesel Fuel
    The approach in Case Study 8-E  of using a com-
  posting installation for biological treatment of soil con-
  taminated with  diesel fuel is rather unique.
  Consequently, it has unique effectiveness for a biologi-
  cal system.  Relatively low residual concentrations
  (less than 50-350 mg oil/kg dry soil) can be achieved in
  a relatively short time period (one week).

  8.4.3     Lessons Learned on How to Improve
          Effectiveness
    In situ  biorestoration.  Recirculation of the ex-
 tracted ground water has positive  effects on soil
 biodegradation. The reason for this is not yet precisely
 known.  It might be due to the fact that surfactants,
 which are produced by microorganisms, are recircu-
 lated through the contaminated soil. Another explana-
 tion can be that the recirculating water contains
 degradation products, which can more easily be
 broken down than the original contaminants. In this
 way, there is an extra stimulation of the microbial ac-
 tivity, which influences the total biodegradation.
    The positive effect of the addition of surfactants is
 still questionable. Fundamental research and practical
 experience  indicate that the effect on degradation is
 negative. Detergents that can be applied need  to be
 biodegradable  (the original contamination should not
 be replaced by contamination with surfactants).  How-
 ever,  in several research projects microorganisms
 preferred these surfactants as a food source and
 degraded the original contamination less than before
 surfactant addition.
    When applying surfactants, clogging problems also
 occurred, due  to complex interactions between soil
 surfactants,  soil particles, contaminants, and microor-
 ganisms.
    Addition of microorganisms to the subsoil, with the
 aim of enhancing the biodegradation, is being used by
 a few  companies  on a field scale. These microor-
 ganisms can either be selected in the laboratory or can
 be  cultured at the laboratory after being sampled from
 the contaminated  site. Although this  approach has
 some  potentially beneficial effect,  it has not been
 proved to date. Cost-benefit calculations are unavail-
 able.
   The experiences with hydrogen peroxide (H2O2) as
 a supplemental  oxygen source are not  consistent with
 respect to effectiveness. While in the Asten  project
 hydrogen peroxide was chosen as the most promising
oxygen source  after laboratory  research, the results
with H2O2 in the Eglin project are very disappointing.
Currently, there is no explanation for this difference in
  results. The differences may be due to enzymatic
  breakdown of H2O2 or due to abiotic degradation.
    Another cause could be the different temperatures
  in Florida and The Netherlands. As long as the ef-
  ficiency of hydrogen peroxide  cannot be predicted,
  preliminary (field) treatability testing is necessary when
  considering its application.
    Venting of volatile contaminating compounds in the
  unsaturated zone and treatment of these components
  above ground can be  a cost-effective  method for
  removal compared to in situ biorestoration by means of
  recirculation of water. Apart from the volatilization of
  contaminants, venting will enhance biodegradation be-
  cause of the extra oxygen supply. Also combinations
  of venting in the unsaturated zone and the application
  of a water recirculation system can be cost-effective.
    Off-site biorestoration.  The application of an off-
  site rotating bioreactor for degrading oily contaminants
  (Case Study 8-E) is one waiy of  improving the effec-
 tiveness of off-site biological! soil  treatment compared
 to other biological techniques like landfarming and in
  situ biorestoration.

 8.4.4     Lessons Learned In Site Preparation and
          Testing
    The success of in situ biorestoration, as all in  situ
 technologies, largely depends on the permeability of
 the soil. Since the  soil itself is used as a bioreactor, the
 permeability is the gate to the degradation. When per-
 meability is limited, in situ biorestoration is adversely
 affected.
    If the permeability of the soil allows in situ biores-
 toration, the  most important limitation (for oily con-
 taminants) is usually oxygen supply.  In fact, in
 demonstration projects, oxygen is always the limiting
 factor. Understanding  the behavior of oxygen in  the
 subsoil and  the possibilities for enhancing  oxygen
 supply are the prime technological challenges to  im-
 proving in situ biorestoration effectiveness.
   Because of the general  complexity of soils, the
 degradation process can never be predicted complete-
 ly. Therefore,  preliminary testing and evaluation, both
 in the laboratory  and in field tests,  will always  be
 necessary. The field  tests should include oxygen
 utilization  rates and potential clogging  problems.
 These clogging problems can occur as a result of the
 reaction of oxygen with iron or manganese present in
 the soil. Clogging  can  also be caused by excessive
 bacterial growth, due to the stimulation of microbial ac-
 tivity.
   Biodegradation  is necessarily limited to those  or-
 ganic compounds that  can be degraded biologically.
 To date,  there is a broad range  of compounds that
 have  been proved in principle  to be biologically
degradable. As research continues, more  and more
compounds can be added. Continued research and
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Chapter 8	

demonstration will be needed to achieve biodegrada-
tion in the field.
   Some contaminants seem to be only biodegradable
in the presence of other, easily degradable con-
taminants. This degradation  is  called co-metabolism.
For example, chlorinated alkenes can be degraded in
the presence of oxygen and methane, while methane-
oxidizing bacteria (methanotrophs) obtain energy from
the   oxidation  of   methane.   The  enzyme
monooxygenase, which then is formed, brings about
the degradation of chlorinated alkenes (McCarty et al.
1989;Janssen etal. 1987).
   Inoculation with (selected) microorganisms has not
been shown to improve degradation results.  In most
cases, the indigenous population, which has been
adapted to the specific contamination present, can be
stimulated in order to reach comparable degradation
results. It is expected that the strategy and technology
of isolating and selecting microorganisms will  be most
beneficial for very specific contaminants.

8.5   Residuals and Emissions
   The residuals and  emissions from biological treat-
ment can be divided into the following categories:
   ซ Residual concentrations of contaminants and in-
     termediates in soil and ground water

   • Emissions  of contaminants and intermediates
     with the ground water being discharged

   ซ Emissions of contaminants and intermediates into
     the air.

   When treating soil biologically,  it is typical that,
depending on the type of soil and contaminant, some
residual concentrations will remain after treatment. It
has to be determined whether these low residual con-
centrations can be regarded  as safe.  Attention should
also  be paid to compounds that can be formed by
faiodegradation and in  certain cases appear to be
resistent to further degradation.
   A similar problem is the presence of residual con-
centrations in the ground water; site-specific charac-
teristics determine whether or  not low concentrations
of contaminants should  be  accepted as safe  in the
ground water to be discharged.
   The above mentioned subjects of concern are also
 applicable to the exhaust air from either soil venting,
 (biological)  ground water treatment, or composting.
 Petrol-contaminated soils should not be treated in a
 rotating bioreactor without provisions to reduce emis-
 sions of volatile aromatics into the air. At the Soest
 project no  significant emissions of aromatics from
 dlesel-polluted soils were measured.  However, at the
 beginning of the incubation,  hydrocarbon emissions of
 up to a lew hundred mg/m3 may sometimes occur.
   The use of activated carbon to treat air emissions is
a relatively expensive treatment method; consequent-
ly, a compost filter is potentially very welcome. How-
ever, the effectiveness of compost filters generally is
rather poor. Catalytic oxidation can be a good alterna-
tive for larger amounts of contaminants in air to be
treated.

8.6   Factors and Limitations to Consider
      for Determining Applicability of the
      Technology
   A general advantage  of biorestoration is the fact
that it is an "environmentally sound" technology; there
is very little or no generation of waste products. Atten-
tion should be paid, however, to the formation of inter-
mediates, which in some cases, can be  more harmful
than the original contaminant (for  example
tetrachloroethylene degrading to vinyl chloride).
   Another advantage of biological treatment is its
cost-effectiveness. Off-site landfarming  will generally
be cheaper  than  alternative techniques like thermal
treatment or soil washing after excavation. On the
other hand, the treatment period  is relatively long,
ranging from a few weeks for composting up to one or
two seasons for landfarming.
   In situ biorestoration  is often more  cost-effective
than in situ soil washing, largely due to the shorter time
period that is needed for cleanup.
   As mentioned earlier, it  is typical that biological
treatment will leave some residual concentrations of
contaminants in the soil. This is caused by limitations
in the "bio-availability" of contaminants at low  con-
centration levels. The  problem of bio-availability is not
fully understood. Several factors might play  a  role.
The concentrations may be too low to be favorable as
an energy source for the microorganisms, or the con-
centrations can be too low to induce the production of
certain enzymes necessary for biodegradation.
   In certain countries, such as The Netherlands, the
limited capability of microbial treatment to reach low
residual concentrations may  lead to limited or no pos-
sibilities for application. For example, the relatively low
residual concentration of less than 50-350 mg/kg dry
soil achieved in the Soest project is still higher than the
A-level defined in the Interim Soil Clean-up Act (50
mg/kg dry soil for soil containing  10 percent organic
matter).            '           '•."..
   As regards in situ biorestoration, the permeability of
the soil is a very important parameter. Generally, a Kf-
value  of 10'5 m/s  is regarded as  being the minimum
permeability required for successful application.
   When considering the use of biological treatment,
the following should be considered:

    Biological treatment in general
,   ป Biodegradability of contaminant(s)
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                                                                    Microbial! Treatment Technologies
   • Microbial parameters (total cell count,  nitrifiers,
    denitrifiers, hydrocarbon degraders)
   • Inoculation
   • Oxygen and redox conditions
   • Oxygen demand (TOC, DOC, BOD)
   • Ntotai, NH4+, NOa, NOa concentrations
   • Phosphate concentration
   • Nutrient demand
   • Contaminant degradation rate
   • Bio-availability
   • pH
   • Temperature
   • Concentration of potential toxic components
   •• Mass balance (contribution of biodegradation ver-
    sus vaporization)
   • Formation and fate of intermediates
   • Residual concentrations of contaminant and inter-
    mediates.

   In situ biorestoration
   • Partition of contaminants in soil and ground water
   • Soil permeability
   • (Geohydrological) isolation
   • Fe and Mn concentrations
   • Heterogeneity of the soil
   • Behavior of the oxygen source in the subsoil and
    effectiveness of providing oxygen  to  microor-
    ganisms.

   Biological treatment of ground water
   • Partition of contaminants in soil and ground water
   • Soil permeability.

   Ex situ biological soil treatment
   ป Consequences for excavation and transport
   • Partition of contaminants in soil and ground
    water.

   When cleaning up contamination of both the soil
and ground  water, the partition of contaminants be-
tween soil and  ground water is important. Most con-
taminants will be present both in an adsorbed form on
soil particles and in  a dissolved form in the ground
water. The monitoring of the cleanup process can  at
first be based on the concentrations of contaminants in
the ground water. When  low concentrations in the
ground water have been reached and there  is a very
slow decline in concentrations, the recirculation
process should  be stopped for a while in order to allow
the concentrations in soil and ground water to reach a
new equilibrium. This must be repeated several times.
Only when the concentrations in the  ground  water do
not rise after a period of rest and the concentrations in
the soil are sufficiently low, can termination of the
remedial action be considered.

8.7   Costs
   In situ biorestoration. A wide range of site- and
system-characteristics and remedial objectives influen-
ces the total costs for  in situ biorestoration projects.
Included are:
   ซ Geology and soil structure
   • Type and concentrations of contamination
   ซ Distribution of contamiinants in the subsoil
   • Total surface  and volume of the contaminated
     area
   • System characteristics:  recirculation, water and
     gas treatment, etc.

   In the case of the Asten site (Case Study 8-B), total
costs for in situ biorestoration of a  sandy soil and
ground water contaminated with petrol are estimated
to be about 70-80 percent of the costs for excavation
and treatment off-site. As regards total costs, a great
advantage of in situ biorestoration for industrial sites is
the fact that commercial activities can be continued
during the cleanup period; because the process occurs
largely in the soil itself, there is no need for stopping
industrial activities.
   For smaller sites, like petrol stations, costs vary be-
tween 40 and 250 US$/m3 (1990).  For larger sites,
costs are estimated up to 150 US$/m3. Of these costs,
operating and  maintenance costs account for about
two-thirds of the  total costs. Generally, approximately
one-third of the cost is due to preliminary research and
installation costs, which occur in about equal amounts
(Staps1990).
   If applicable, in situ  biorestoration will in many
cases be more cost-effective than other techniques,
such as incineration, or soiil washing of the excavated
soil plus treatment of the ground water (approximately
70-170  US$/m3  excluding excavation and transport
costs).
   On-site biological  treatment of ground water.
The  on-site treatment  of HCH-contaminated ground
water with the rotating biological contactor (RBC) is es-
timated to lead to a cost reduction of at least 30 per-
cent (with  costs ranging  from US$102,000 to
US$130,000) compared to using activated carbon plus
physical/chemical  treatment alone  (costing
US$175,000). In  Table  8-1, treatment costs are given
in relation to treatment techniques and removal ef-
ficiencies. For a combined biological/physical/chemical
treatment, costs  have been  calculated for three dif-
ferent biological removal efficiencies. Also costs for a
one-stage physical/chemical treatment without biologi-
cal pretreatment are given.
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 Chapters
 Table 8-1.  Costs of control techniques by levels of pollutant removal efficiency (in US$).
      Removal efficiency, RBC
                 Costs
HCH
70%
60%
20%
0
Benzene/
Chlorobenzene
95%
95%
60%
0
RBC
55,000
45,000
17,500
-
Activated
carbon
7,500
10,000
50,000
100,000
Physical/
chemical
installation
40,000
50,000
62,500
75,000
Total
102,500
105,000
130,000
175,000
 8.8  Future Status of Case Study
      Processes and Microbial Treatment
      as a Whole

 8.8.1 Future Status of Case Studies
    Results of demonstration tests on applying biologi-
 cal treatment as a substitute to airstripping at the
 Skrydstrup site (Case Study 8-A) are promising.
 Therefore, additional experiments will  be carried out
 and full-scale treatment is likely to be applied. As the
 operation of the airstripping unit brings along high
 energy  costs, biological methods are  regarded  as a
 very relevant alternative to bring down operation costs.
 The monitoring  of soil will continue with additional
 microbiological  investigations in the two compart-
 ments.
   The  laboratory and column studies related to the
 Asten site (Case Study 8-B) were finished in 1989. The
 full-scale cleanup was started in 1990 and is expected
 to be finished in 1992.
   Because of the poor results obtained in using
 hydrogen peroxide at the Eglin site (Case Study 8-C)
 and cost estimates that were very high for cleanup, the
 Air Force decided not to cleanup the site with in situ
 bforestoratfon.
   The research project related to RBC-application for
 on-stte ground water treatment at Bunschoten (Case
 Study 8-D) was finished. Because of the project
 results, rt was recommended that more biological tech-
 niques like RBC's should be applied in ground water
 remedial action,  especially  for (chlorinated) aromatic
 contaminants.
   Based on the results of the  rotating bioreactor at
 Soest (Case Study 8-E), it cannot be guaranteed that
the A-ievel for mineral oil, required by The  Nether-
 lands, will be achieved by soil treatment in the bioreac-
tor. Therefore, there  are no practical applications for
this kind of biological cleaning of oil-contaminated soil
 in The Netherlands.
 8.8.2 Future Status of Microbial Treatment In
      General
   Given the level of international research in the area
 of microbial treatment, it is expected that the scope of
 application will be  broadened in the coming years.
 More compounds will be proven to be susceptible to
 microbial  degradation. Thus, the importance of
 microbial treatment  might improve in the future. How-
 ever, the status of microbial treatment will depend on
 the residual concentrations that can be  reached  and
 the standards that have been set by the authorities.
 For example,  in The Netherlands, the applicability of
 microbial degradation is limited because of the relative
 severely standards.
   Available research indicates that there is a factor
 called "bio-availability", which refers to  limits on the
 availability of the contaminants in the soil to the water.
 In order to be available for microorganisms, the con-
 taminants must be dissolved in the  water.  Bio-
 availability is of major concern for compounds with a
 low  water solubility. This  is one  of  the current
 obstacles for broadening the field to the further ap-
 plication of microbial treatment.
   As regards the range of compounds that can be
 degraded by means of microbial treatment, there  can
 be a further extension of applicability to other com-
 pounds  like PAHs or other chlorinated  compounds.
 The permeability of the soil will remain a specific limita-
 tion for the application of in s/fc/biorestoration.
   The status  of microbial treatment for ground water
 is expected to have more possibilities for growth, be-
 cause here the microbial treatment is often followed by
 a polishing step, for example, with activated carbon.
 The  philosophy here is that  every bit of biological
 degradation that can happen  first helps reduce total
treatment costs when alternative and more expensive
technologies must be added at the end.
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                                                                    Microblal Treatment Technologies
REFERENCES

     Janssen, D.B., Grobben, G. and Witholt, B.H. Toxicity of chlorinated aliphatic hydrocarbons and degrada-
     tion by methanotrophic consortia. in: O.M. Neijssel, R.R. van der Meer and K.C.A.M. Luyben, (Eds.),
     Proceedings of the Fourth European Congress on Biotechnology, Vol. 3. Elsevier Science Publishers,
     Amsterdam, 1987.

     McCarty, P.L., Semprini, L. and Roberts, P.V. Methodologies for evaluating the feasibility of in situ
     biodegradation of halpgenated aliphatic ground water contaminants by methanotrophs. Proceedings,
     AWMA/EPA Symposium on Biosystems for Pollution Control, Cincinnati, Ohio, Feb. 21-22,1989.

     Staps, S.  International evaluation of in situ biorestoration of contaminated soil and ground water RIVM-
     report no. 73878006,1990.
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Selecting Remedies at a Complex Hazardous Waste Site

Thomas O. Dahl
United States Environmental Protection Agency
National Enforcement Investigations Center, Denver, Colorado 80225
United States
ABSTRACT

   Selecting remedies at a complex hazardous waste site is a difficult but necessary process. Countries use a variety
of approaches. This chapter uses the Stringfellow Site in California, United States (U.S.) as a case study to describe
the process used by the United States Environmental Protection Agency (U.S. EPA) and examine remedial selection
problems of mutual concern to many countries. The environmental problem at the Stringfellow Site and the remedy
selection process are described. Major conclusions include:

   • Selecting remedies at a complex site requires a methodical approach to move from uncertainty to rational
    decisions.

   • Flexibility within the process must be maintained to address inevitable unforeseen circumstances.

   ป Conducting treatability studies as eariy as possible and arriving at conclusions from interim remedies are
    important in effective remedy selection.

   • Constructing remedies is not the final chapter in cleaning up complex sites; long term monitoring is required
    to validate remedial hypotheses and to determine success.
9.1   Introduction
   Selecting remedies at a complex hazardous waste
site is a difficult, but necessary process.  A variety of
approaches are used by countries.  The process
selected by a given country is driven by such variables
as sense of urgency, philosophical approach, degree
of experience and funds available.  To illustrate the
process used by the  U.S. and to highlight areas of
mutual concern for many countries, a case study is in-
cluded below. This case study describes the remedy
selection process at a U.S. site.
   During the 1950's,  southern California was under-
going rapid post-war  industrial growth.  One unfor-
tunate outcome  was the generation of increasing
amounts of hazardous waste. Consequently, the State
of California began seeking safe disposal sites for
these waste  products.  This search led to Pyrite
Canyon, a box canyon on the southern slopes of the
Jurupa Mountains, approximately 80 kilometers (50
miles) east of Los Angeles, California (see Figure 9-1).
   nderlying the shallow alluvium in  Pyrite Canyon is
bedrock of  metamorphic arid igneous origin.   It was
reasoned that the combination of the bedrock floor, a
cemented alluvial cone, and the construction of a con-
crete barrier dam across the surface drainage channel
could provide a suitable location for a disposal site.
   In 1955, the Stringfellow Quarry Company received
a permit to operate a hazardous waste disposal facility
in the canyon.  The 6.9 hectares (17 acres) disposal
site was operated from 1956-1972 and consisted of as
many  as 20 surface impoundments (see Figure 9-2).
About 200 industries sent 130 million liters (34 million
gallons) of liquid industrial process wastes containing

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Chapters
Figure 9-1. Location of the Stringfellow Waste Disposal
          Site.

spent acids and caustics, solvents, pesticide by-
products, metals, and other inorganic and organic con-
taminants to the site by trucks which discharged the
wastes into the ponds.
   In 1968, site operators noted soil  discoloration on
the downgradient side of the concrete  barrier dam.
Over the next several years, the site had an increasing
number of problems. These problems included surface
water overflow during  heavy  rains, and the ap-
pearance of inorganics in ground water at the site
monitoring  well which was over  1,000 meters (3,400
feet) downgradient from the site. These events cul-
minated in  November 1972 with the voluntary closing
of the site and, despite subsequent efforts to reopen it,
the site's land use permit was revoked in 1974.  Sub-
sequently, the site reverted to the State of  California
because the owners had not paid taxes.

9.2  Interim Studies/Remedies
   Between 1975  and 1982 the State of California
conducted studies and implemented interim remedies
at the site, though with limited budgets.  The studies
determined that:
   ป The cemented alluvial cone was  underlain by an
    alluvial, permeable stream channel extending to
    about 27 meters (90 feet) below grade.
                                                                                        100-  0  100' CTO-


                                                                                           SCALE IN FEET

                                                                                          LtOENP
                                                                      ป CONCRETE DAM


                                                                  •ป COLLECTION SUM*
                                                                                           AREAS CONSIDERED
                                                                                           T0 " CONTAMINATED
                                                                                           FROMFONOSFRAV
Figure 9-2. General site configuration by 1972 for dis-
          posal operations.

   • The bedrock underlying the downgradient end of
    the site and the concrete barrier dam were frac-
    tured,  providing potential pathways for off-site
    contaminant migration.

   • Ground waters were entering the site from
    upgradient springs.

   • Permeable, alluvial materials existed next to both
    ends of the concrete barrier dam, providing addi-
    tional potential pathways of contaminant migra-
    tion.

   • Site-related  contaminants, including  metals and
    chlorinated organics, were found in ground waters
    at and downgradient from the site.

   Interim  remedial actions  conducted  during this
period included:
   • Millions of liters of on-site pond liquids were
    hauled off-site for disposal.

   • Pond bottoms and soils from the northern half of
    the disposal site were excavated down to bedrock
    and moved to the southern half of the site.

   • Lime kiln dust was disked into surface materials
    of the southern half  of the site; kiln dust was
    placed over the entire disposal site.  These ac-
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                                                Selecting Remedies at a Compllex Hazardous Waste Site
     tions were taken in an unsuccessful effort to
     neutralize the highly acidic wastes.

   • French drains were placed along bedrock lows in
     the northern half of the site to carry subsurface
     liquids to a sump from which they could  be
     pumped to off-site storage and disposal.

   * An east-west clay-core barrier dam approximately
     240 meters (800 feet) long was constructed near
     the old concrete dam, from canyon wall to canyon
     wall and from surface to bedrock.

   • A french drain was placed at the upgradient base
     of the clay core barrier dam to  take hydraulic
     pressure  off the dam and carry liquid to two
     sumps for pumping to off-site storage and dis-
     posal.

   • Silica gel was injected into fractured bedrock un-
     derlying the clay core dam in an effort to seal frac-
     tures.

   • The disposal site was covered with an  ap-
     proximately 0.3  meter (1  foot) layer of clayey
     material, and then a 0.3 meter (1 foot)  layer of
     topsoil.

   • A surface drainage system was installed on the
     sides of the disposal site to carry uncontaminated
     runoff around the site.

   • A 14-well monitoring network  was installed
     downgradient from the site.

   •Approximately 760 cubic  meters (1,000 cubic
     yards) of  DDT-contaminated soil  were removed
     from the site and disposed of offsite.

   • Two mid-canyon extraction wells were con-
     structed approximately 600 meters (2,000 feet)
     downgradient from the barrier dam.

   In 1980, things changed in many ways when  the
U.S. passed the Comprehensive Environmental
Response,  Cleanup and Liability Act  (referred to  as
"Superfund") to deal with abandoned hazardous waste
sites such as Stringfellow.  In 1982 the site was placed
on the U.S. EPA's National Priority  List (NPL)  as
California's highest ranked site.  Including the site on
the NPL made it eligible for Superfund remedial action
money.

9.3   Litigation
   Work done at the Stringfellow site up to 1982 was
significant but not sufficient to fully define the areal and
vertical extent of contamination or to mitigate all con-
tamination.  By the fall of 1982, U.S. EPA had iden-
tified approximately  200 industries that had sent
wastes to  the site.  Under Superfund, U.S. EPA
notified  these  industries, as  well as  former
 owners/operators/transporters, that they  had been
 identified as Potentially Responsible Parties  (PRP's)
 and tried to have them acpept responsibility for neces-
 sary studies and remedies.
    Efforts toward  a, PRP-led cleanup failed, and in
 April 1983 the  U.S. and State of California filed suit
 against 31 of the  PRP's in U.S. District Court.  The
 industries involved represented over 80 percent of the
 liquid volume that had been disposed at the site.
 These litigation efforts continue in  one of the most
 heavily litigated cases in the U.S. While these efforts
 continue, U.S.  EPA pays for  the  necessary
 studies/remedies with the intent of  recovering costs
 from the  responsible parties.  In addition, the U.S. EPA
 and the State of California meet regularly with a techni-
 cal  committee of PRP companies to discuss site
 developments and to encourage PRP participation in
 necessary studies/remedies;.

 9.4  The Remedial Investigation/Feasibility
      Study (RI/FS) Process
    In 1983, the  U.S. and State of California decided to
 conduct  a Remedial Investigation/Feasibility Study
 (RI/FS) at the Stringfellow site to determine the areal
 and vertical extent of contamination, assess risks, and
 select remedies.
   The process which U.S. EPA uses  to select
 remedies is specified in the National Oil and Hazard-
 ous Substances Pollution Contingency  Plan (NCP)
 and is shown in Figure 9-3; the process  seeks to
 gather progressively more and more  detailed informa-
 tion.  Once the agency receives information that there
 may be a problem, it conducts a Preliminary Assess-
 ment, which'makes use of readily available information
 to see if  further action is necessary.  If it is, a  Site In-
spection  is conducted which gathers more  extensive
 information, perhaps including some sampling.
   Data  collected during the Preliminary Assess-
 ment/Site Inspection phases are put into a site  scoring
 model. If the numeric score is high enough, the site is
 placed on the National Priorities List and a RI/FS is
 conducted. Throughout the process, investigators
 must be aware of the need for short term actions (e.g.,
 removal  of leaking drums, construction of a security
'fence, etc.); these  are termed "Removal Actions" by
 the U.S. EPA. Similarly, if it becomes apparent during
 the often lengthy RI/FS process that interim remedial
 actions are called for (e.g., construction of a leachate
 treatment plant), they should be started rather than
 waiting for the whole process to be completed.
   Once a decision has been made to conduct a
 RI/FS, a  planning or Scoping phase is begun.  This
 phase includes activities such as:
   • Meeting with study participants to discuss impor-
     tant  issues and assign responsibilities.
                                                 99

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Chapter 9
    FROM:
    •  Preliminary
      Assessment
    •  Site
      Inspection

    •  NPL
      Listing
                                      SITE          ;   TREATABILITY
                             CHARACTERIZATION: INVESTIGATIONS
SCOPING
 OF THE
  RI/FS
              DEVELOPMENT
                    AND
                SCREENING
                     OF
              ALTERNATIVES
                                                           DETAILED
                                                         ANALYSIS OF
                                                        ALTERNATIVES
TO:
   Remedy
   Selection
   Record of
   Decision
   Remedial
   Design
   Remedial
   Action
Figure 9-3. U.S. Superfund remedy selection process.
  • Evaluating existing data to develop a conceptual
    site model to assess the problem as it is under-
    stood at the time and  to identify potential ex-
    posure pathways and health and/or environmen-
    tal receptors.

  • Beginning limited field investigations, if existing
    data are not adequate to scope the project.

  • Identifying preliminary remedial action objectives
    for  each contaminated medium,  and likely
    remedial actions. These will change with time as
    more information becomes available, but concep-
    tualizing early is extremely useful.

  ซIdentifying the preliminary criteria that will apply to
    site characterization and remediation. There can
    be many of these, particularly if several regulatory
    agencies exist; if criteria can be identified early,
    the site investigators can use them as work goes
    on.

  ป Determining data needs and the level of analytical
    and sampling certainty required for additional data
    collection.  For example, initial data may show
    that a problem exists but may not be enough to
    define actual risks or select remedies.

  ซ Evaluating the need and setting the schedule for
    treatability studies to better evaluate  potential
    remedial alternatives.
                             • Designing a data collection program that
                               describes sampling and analytical requirements.
                               Often jt is difficult to balance between a concern
                               for controlling costs and perfection. However,
                               one must not forget that the resulting process
                               must yield conclusions that can be defended and
                               from which the site can be characterized and the
                               problem solved.

                             • Developing a work plan that documents the scop-
                               ing process and outlines anticipated future tasks.

                             • Identifying health and safety protocols required
                               during field investigations and preparing a site
                               health and safety plan. As one learns more about
                               the problem, these may have to change to reflect
                               greater or lesser threats.

                             • Meeting with the community and developing a
                               community relations plan. The studies and
                               remedy implementation may take much time; and
                               it is extremely important to  establish a program
                               that both keeps the public well informed and asks
                               for its input.

                             Once the scoping phase of the RI/FS process is
                          completed, a Site Characterization phase is  begun.
                          This consists of:
                             • Conducting field  investigations.  Some of the
                               primary effort includes defining the areal and ver-
                              tical extent of contamination and degree of threat
                                             100

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                                                Selecting Remedies at a Complex Hazardous Waste Site
    to health and the environment. Determining how
    much data to collect is always a difficult task, and
    as mentioned earlier requires a balance between
    a concern for controlling cost and perfection.

   ซ Analyzing field samples.  Many analytical techni-
    ques, some at high cost, are available to the in-
    vestigator. Again there must be a balance which
    gets the job done without spending too much of
    the available funds on the analyses and leaving
    too little for the  remedies.  Much  attention must
    also be given to quality assurance/quality control
    methods to assure that the investigator can draw
    conclusions that can be defended.

   • Evaluating the results of the data analysis to char-
    acterize the site and develop a baseline risk as-
    sessment.  The baseline risk assessment is
    designed to provide an evaluation of the potential
    threat  to  human health and the environment if
    there was no remedial action.  It provides the
    basis for determining whether or not remedial ac-
    tion  is necessary and for justifying the remedial
    actions.  The assessments  include contaminant
    identification, exposure  and toxicity assessments,
    and  risk characterization.  Where possible,  as-
    sumptions (such as dose/response relationships,
    standard ingestion rates  for receptors, etc.)
    should be standardized to remove variables from
    this difficult analysis.

   • Determining if data are sufficient for developing
    and evaluating potential remedial alternatives. As
    field investigations continue and data are
    analyzed, new concerns often arise beyond those
    which were identified at the beginning.  For ex-
    ample, additional contaminants may be identified
    which are not treatable by the same technologies
    (e.g.,  extractable versus  volatile  organics).
    Therefore, it is not uncommon to have to rescope
    investigative  approaches to  address  these con-
    cerns.  The use  and  acceptance  of  such a
    dynamic process is very important.  If the process
    is  rigid, the result may  be a well conducted,  but
    entirely inadequate investigation.

   The Development and Screening of Alternatives
phase  of the  RI/FS process is one which can be
described as iterative, but in fact  is  part of the neces-
sary thought process which begins at the time of Scop-
ing. It includes:
   • Identifying remedial action objectives.  As dis-
    cussed above, the earlier these can be identified
    the  better so that the  investigations  can be
    designed to address them.

   • Identifying potential technologies that will address
    these objectives. Often there will be  a variety of
    technologies that are potentially applicable.  For
    example, if there is a volatile organics comtamina-
    tion problem, both activated carbon and air strip-
    ping  are potentially applicable technologies.
    Later evaluations  may demonstrate  that one is
    more appropriate for use than the other (e.g., be-
    cause of cost, presence of other organics, etc.).

   • Screening the technologies. Various criteria are
    possible; the U.S. EPA uses  effectiveness, im-
    plementability, and cost.  In general,  one should
    use a set of criteria that eliminates technologies
    that are not applicable.   For example,  if the
    presence of  a particular contaminant makes a
    technology ineffective, or if the necessary depths
    of application are not achievable, those tech-
    nologies should be screened out. The screening
    mechanism selected should attempt to balance
    the desire to reduce options as quickly as pos-
    sible against the desire; to leave options open for
    finally selecting the "right" remedial option.

   • Assembling technologies into remedial alterna-
    tives that address the problem.  Again the U.S.
    EPA uses the criteria of effectiveness, implemen-
    tability, and cost.  Effectiveness focuses primarily
    on whether the alternative protects human health
    and the  environment.  Implementability focuses
    on  the technical aspects (i.e.,  the ability to con-
    struct and successfully operate) and  administra-
    tive aspects (e.g.,  the ability to obtain approvals
    for  using the  alternative).  Cost focuses on rela-
    tive comparisons between alternatives, recogniz-
    ing that a high degree of accuracy is not possible
    at this stage.  There i;> a wide range of alterna-
    tives  which can be developed.  The U.S. EPA
    develops a range which has as its upper end an
    alternative which prevents, as  much as possible,
    the need for any long term management of
    residuals and untreated wastes. The lower end of
    the range is a "no action" alternative.  The best
    approach is to find a cost-effective alternative that
    satisfies  the upper end of the range.  However,
    this is not always possible for any  number of
    reasons, including the important variables of high
    costs and technical uncertainty.

   If available data are insufficient to evaluate the
remedial  alternatives, Treatability Investigations
(bench and/or pilot scale) may be necessary.  The
point at which these can be conducted varies; they
should be conducted as early as possible within the
process. In some cases the need  can't be predicted
until the screening process has begun.  For example,
as studies continue and more data  become available,
it may become clear that  a certain technology seems
to be promising (i.e., anticipated cost or performance).
In these cases, extra time will be required to perform
the necessary treatability studies and then  resume the
remedial selection process.
                                                 101

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 Chapter 9
    The next step in the RI/FS process is the Detailed
 Analysis of Alternatives.  The criteria which are used
 by U.S. EPA for this analysis are:
    • Overall protection of human health and the en-
     vironment

    ซ Compliance with "applicable or relevant and ap-
     propriate requirements" (ARAR's)

    • Long term effectiveness and permanence

    • Reduction of toxicity, mobility, or volume through
     treatment

    ป Short term effectiveness

    • Implementability

    • Cost

    ป State acceptance

    ป Community acceptance.

    Each alternative is analyzed against each criterion
 and then compared against one  another.  This  iden-
 tifies strengths and weaknesses so that U.S. EPA can
 evaluate the alternatives and prepare  a Proposed
 Plan. This plan, which summarizes the remedial  alter-
 natives  and  identifies a preferred alternative, is
 presented to the public for comment.  After considering
 the comments received, U.S. EPA documents the
 remedial alternative  chosen in a  Record of Decision.
 Then the selected alternative is designed and  con-
 structed.
    Successful construction of facilities is not the end of
 the  process.  It  is extremely important that a  com-
 prehensive monitoring system be designed  and imple-
 mented.   Since there  is not enough  long  term
 experience with remedies, it is a good idea to start with
 a system that errs  on the high  side for monitoring
 points, parameter coverage, and frequency of  sam-
 pling.  As experience  is gained, these can be
 diminished or modified to reflect new information. It is
 also important to select and use statistical techniques
 to characterize cleanup over time.  Apparent changes
 may be  subtle  or misleading, and statistical sig-
 nificance is necessary for decisions over time.  Initial
 predictions of cleanup times should be viewed with
 caution,  as considerable uncertainty often  accom-
 panies the necessary calculations.

 9.5  Stringfellow Site RI/FS
   Beginning in 1984, a large number of technical site
studies (see  Table 9-1) and treatability studies  (see
Table 9-2) were conducted at and near the Stringfellow
Site as part of the RI/FS process.  Most of these were
conducted under the direction of the State of California
and the U.S. EPA.  Several were conducted for com-
panies that had originally sent wastes to the site.  Be-
Table 9-1. Stringfellow Site technical studies.


  Environmental (soil, air, water) sampling

  Geology/hydrology

  Fault/fracture survey

  Geophysical
   - Electromagnetic conductivity
   - Resistivity
   - Seismic

  Soil gas sampling

  Hydraulic testing

  Ground water modeling

  Air modeling

  Risk assessments
cause it was increasingly clear that completion of the
RI/FS process for this complex problem would  take
much time, numerous additional interim remedies were
implemented. To date, these have included:


Table 9-2. Stringfellow Site treatability studies.

 Reverse osmosis

 Carbon adsorption optimization

 Carbon regeneration

 Incineration

 Metals precipitation

 Air stripping

 Ultraviolet oxidation

 Dewatering tunnel (conceptual study)

 Ion exchange

 Stabilization/solidification

 Rotating biological contactor

 Ultrafiltration

 Additional technology evaluations (ongoing)
   ' Provision of an alternate drinking water supply to
    approximately 500  residents of nearby Glen
    Avon, California to protect them from potential
    hazard exposure.

   ' Diversion of surface waters around and from the
    on-site area to prevent contamination.
                                                  102
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                                                Selecting Remedies at a Complex Hazardous Waste Site
   • Interception and diversion of shallow uncon-
     taminated ground water upgradient of the site.

   • Improvement of surface drainage patterns.

   • Construction of a pretreatment plant in  the mid-
     canyon area to remove metals and organics from
     on-site, mid-canyon and lower canyon extracted
     ground waters.  Treatment includes lime  and
     sodium hydroxide additions for metals  removal
     and activated carbon for organics  removals.
     Treated waters are taken to a sewer drop station
     and then discharged offshore in the  Pacific
     Ocean. The plant began operation in late 1985,
     and by January 1992 had successfully treated
     about 170 million liters (45 million gallons) of con-
     taminated ground water.

   •Installation of a subsurface french  drain
     downgradient from the barrier dam to intercept
     shallow, contaminated  ground water for later
     treatment at the pretreatment plant.

   •Installation of additional mid-canyon extraction
     wells to improve the efficiency of the capture sys-
     tem. The intercepted water is sent to the pretreat-
     ment plant.

   • Establishment of a  systematic ground  water
     monitoring program to detect any encroachment
     of site-related contaminants.

   • Installation of a lower canyon extraction well sys-
    tem approximately  1,200 meters (4,000 feet)
     downgradient from the  barrier dam to  capture
     ground water contaminants that otherwise would
    flow into the community  (PRP companies imple-
     mented this interim remedy).

   In 1987 the Remedial Investigation (Rl) report was
released to the public; some of the major conclusions
included:

On-site Conditions
   • Approximately 83 million liters (22 million  gallons)
    of contaminated ground water are held in uncon-
    solidated soil and rock material on-site.  An  un-
    determined amount of contaminated ground water
    is in the fractured bedrock underlying the site.
    Contaminated ground water was found as deep
    as 60 meters  (200 feet) below land surface in
    bedrock wells.

   • Most contaminants on-site were found in  the
   .• ground water; the on-site soil (alluvium/fill) is not a
  ,, primary source of mobile  contaminants (solvents,
    metals, etc.). Mobile contaminants were found al-
    most exclusively in the ground water.

   • Contaminated  ground  water is moving
    downgradient from the site, leaving the  site al-
     most entirely through the fractured bedrock under
     the subsurface barrier wall. Sulfates were found in
     percentage concentrations, heavy metals in 10O's
     of mg/L, and volatile and extractable organics in
     mg/L ranges.

   ซ The site contains over 600,000 cubic meters
     (800,000 cubic yards) of unconsolidated soil and
     rock (alluvium, decomposed rock and metamor-
     phic rock) that contains contamination.

   • The on-site barrier/extraction system  intercepts
     and recovers over 80  percent of the potential
     ground water leakage from the site.

   ซ The composition and distribution of on-site con-
     taminated soils, rocks, and ground water are ex-
     tremely heterogeneous.

   • Soils beneath the low permeability site cover but
     above the  water table are principally con-
     taminated with pesticides, polychlorinated
     biphenyls (PCB's),  parachlorobenzene sulfonic
     acid (p-CBSA), a DDT by-product, and traces of
     slightly water soluble organic compounds. These
     soils are also acidic and contain several heavy
     metals at levels above natural background.

   ซ" The pesticides and PCB's in the  unsaturated
     soil/fill on-site are immobile.  The remaining low
     levels of soluble organiics and metals can be mo-
     bilized by leaching through ground water infiltra-
     tion.

   • The on-site soil/fill below the water table has
     many of the same insoluble organic compounds
     in it as the unsaturated  zone; however, levels of
    water soluble organics and heavy metals are
     much higher and appear to be associated with the
    ground water.

Downgradient Conditions
   ซ A plume  of contaminated ground water extends
    over 3 kilometers (2 miles) downgradient from the
    site and  ranges from 60 meters (200 feet)  to
    about 270 meters (900 feet) wide (Figure 9-4).

   • The Stringfellow-related contaminants found  in
    this plume under the community of Glen Avon in-
    clude several organic solvents (trichloroethylene,
    chloroform,  chlorobenzene,  dichlorobenzene),
    sulfate, and p-CBSA.

   • Heavy metals in the ground water extend about
    600 meters (2,000 feet) downgradient from the
    site; they have been tied up or precipitated out in
    the aquifer materials upgradient of this point.

   • Under 1985/86 water level conditions, which are
    affected by  significant  mid-canyon extraction,
    ground water flux past canyon cross sections  is
                                                103

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Chapter 9
                                                                     SUBSURFACE CLAY
                                                                     BARRIER mm GEL
                                                                     INJECTION BENEATH^.
                                                                                      ON-StTEAReA
                                                               >,ซ,*•*"*""•ป  ^TVป
                                                               v'!    ••••"*<^
                                                               ,   HID CANYON      TREATMENT
Figure 9-4. Approximate location of TCE contaminated ground water that extends from the Stringfellow Site into
         Glen Avon.
    estimated to increase from about 45 to 57 liters
    per minute (12 to 15 gallons per minute) in the
    upper portion of Pyrite Canyon below the site, to
    about 110 liters per minute (28 gpm) just north of
    Highway 60 (1,500 meters or 5,000 feet
    downgradient of the site).

   ป The two original mid-canyon extraction wells are
    estimated to extract about 50 to 60 percent of the
    total ground water flow through the mid-canyon.
    The addition of five more interception wells in the
    mid-canyon in late 1986 increased this fraction.

   " Contaminated  surface runoff can discharge from
    the site during sustained rainfall.  Under present
    conditions, no measurable amounts of surface
    water contamination have been found further than
    600 meters (2,000 feet) downgradient of the site.

   ซ Surface soils within 300 meters (1,000 feet) south
    of the site have been contaminated at concentra-
    tions above existing environmental standards.
   • Within the zone  extending about 300  meters
    (1,000 feet) downgradient of the barrier,
    measurable contamination by site-related con-
    taminants was also found in subsurface soils.

Public Health Evaluation

   • Before starting interim abatement actions in 1980,
    the pathways for exposure to the contaminants in-
    cluded air, surface water, soils, and ground water;
    now, the primary exposure pathway of concern is
    migrating contaminated ground water.

   • The  combined maximum  lifetime risk from ex-
    posure to ground  water contaminated with
    trichloroethylene  (TCE) and chloroform in the
    community area, if used for drinking water, ex-
    ceeds the U.S. EPA's  risk  guidelines (i.e., a car-
    cinogenic risk ranging  from 1 in a million to 1  in
    10,000 cancer occurrences).

   • Without site  remediation and  ground water
    cleanup, the contaminants which have already
                                                 104

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                                                   Selecting Remedies at a Complex Hazardous Waste Site
    migrated below the mid-canyon extraction system
    will continue to; migrate downgradient, adding to
    the risk of exposure for the local community.

   • Air emissions modeling indicates that, even if the
    on-site cap/cover were removed to excavate the
    underlying contaminated materials, there  would
    be only a minimum threat to the residents of Glen
    Avon.

   • Contaminated surface soils in the first 300 meters
    (1,000 feet) downgradient from the site's subsur-
    face  barrier  system are  a potential risk  to  in-
    dividuals in  Pyrite Canyon by breathing  in air-
    suspended dust under severe wind conditions.
    Continual  airborne dust from this zone will not
    reach the community area, and the levels  of soil
    contamination in this zone are not an ingestion or
    skin contact health risk.

   • Subsurface soils within 600 meters (2,000 feet)
    downgradient of the site are accumulating
    precipitated  and adsorbed contaminants from
    migrating ground water. While there is no human
    health threat now, this zone must be considered a
    secondary contamination source during remedia-
    tion planning.

9.6  Remedy Selection at Stringfellow
   The data compiled during the technical and
treatability studies were evaluated to  determine ap-
propriate  remedies.   As part of the Feasibility  Study
released in 1988, 86 technologies were screened for
potential application; 30 were retained for remedial al-
ternatives selection.  Seven remedial alternatives were
chosen from these technologies and were analyzed in
detail using the nine criteria discussed earlier.
   The seven remedial alternatives ranged from the
no action alternative to one which included incineration
of on-site contaminants (Table 9-3). As one would ex-
pect,  these alternatives spanned a wide range  of an-
ticipated costs.   A "low cost"  alternative, the on-site
natural flushing and downgradient  plume cleanup op-
tion, was estimated to have a 30-year present worth
cost  (assuming  a 7 percent  discount rate) of ap-
proximately US$131 million (1989 $).  A "high cost" al-
ternative,  the  on-site  soil incineration and
downgradient plume cleanup option, was estimated to
cost about US$742 million (Table 9-4).
   A  Preferred Alternative was selected which  in-
cluded:
   • Dewatering the on-site area with extraction  wells

   • Implementation of soil-gas extraction for volatile
    organics removal in the on-site area, if field tests
    prove favorable

   • Diversion of surface drainage away from the site
Table 9-3. Summary of remedial alternatives resulting
          from  the Stringfellow Site feasibility study.


 Remedial Alternative 1


 The no action alternative, would involve discontinuing on-site
 (Stream  A) and mid-canyon (Stream B) ground water
 extraction and treatment that is presently performed. Also,
 there would be no effort to minimize the generation of
 contaminated leachate from the on-site area; or to clean up or
 stop the further migration of the downgradient plume.

 Remedial Alternative 2


 Natural flushing of the on-site area, and downgradient plume
 cleanup.

 Remedial Alternative 3


 On-site dewatering, extraction and treatment of on-site
 leachate, and downgradient plume cleanup.

 Remedial Alternative 4A


 On-site dewatering, extraction and treatment of on-site
 ieachate, in situ soil-gas extraction, in situ soil flushing, and
 downgradient plume cleanup.

 Remedial Alternative 4B


 On-site dewatering, extraction and treatment of on-site
 leachate, in situ soil-gas extraction, selective soil excavation
 of higher contamination areas, soil treatment and redisposal
 on-site, in situ soil flushing, and downgradient plume cleanup.

 Remedial Alternative 5


 On-site dewatering, extraction and treatment of on-site
 leachate, full excavation of all cliggable soil, soil treatment
 followed by redisposal on-site into the excavation, and
 downgradient plume cleanup.

 Remedial Alternative 6


 On-site dewatering  with extraction and treatment of on-site
 leachate, in situ soil-gas extraction, additional treatability
 studies of on-site soil contamination, and downgradient plume
 cleanup.
    i Continued extraction, treatment and sewering of
     contaminated ground water from the on-site, mid-
     canyon and lower canyon areas,

    | Extraction, treatment and reinjection of ground
     water back into the community area

    i Additional studies to determine whether there is a
     feasible method for further addressing on-site soil
     and bedrock contamination

    i Installation of a multilayered cap in the on-site
     area.
                                                    105

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 Chapters         	.	

 Table 9-4. Estimated cost comparison of revised remedial alternatives - overall site remedy.
                                RA No. 2
                                             RANo. 3
                                                        RA No. 4A
                                    RA No. 4B
                                                                                  RANo. 5
  Total estimated
  capital costs (million
  US$)

  Total estimated
  present worth costs
  7% discount rate
  (million US$)
 $40.7
$131.2
 $44:2
$156.2  "
 $55.5
"$197.8
                                     $253.3
                                     $392.3
                                     $630.9
                                                                                 •$741.7
                                                                                             RA*No. 6
Approximate time
until ground water
cleanup is achieved
(years)
Zone 1
Zone 2
Zone 3
Zone 4
448
162
40
25
Never
162
40
25
' 65
46 '
40
25
60
46
40
25
63
46
40
25
*'*
46
40
25
                                                            $64.7**
                                                           $186.0**
 "RA No. 6 Is the DHS/EPA Preferred Alternative.


 "Estimated time and costs for cleaning up Zone 1 are not clear at this time", the results of"on-going pilot tests of soil treatment
 processes and evaluations based on EPA's nine Superfund criteria may affect what future on-site actions are taken.
   The selection of ground water treatment and dis-
posal methods will address heavy metals, organics
and Inorganics, depending upon levels of contamina-
tion, and desired end uses for the treated water.
   Treatability studies and experience with operating
the interim pretreatment plant which began operation
in late 1985 provided valuable information on how to
effectively treat the ground waters and what problems
to anticipate. When trying to deal with a complex site
such as the Stringfellow Site,  numerous interactions
and interferences may occur.   For example, on-site
ground waters at Stringfellow contain percent levels of
sulfates.  When these  waters  are  treated for metals
removal by lime addition, a large amount of  gypsum
sludge  is also generated.  These  metals/inorganics-
laden sludges in turn are disposed of off-site as, haz-
ardous wastes.
   Another example of potentially hidden costs results
from the large percentages of organics that cannot be
identified by conventional gas  chromatography/mass
spectroscopy (GC/MS)  methods.  Only about 5 per-
cent of the organic carbon in on-site ground waters at
Stringfellow is identifiable by  the  GC/MS methods;
therefore, more activated carbon is necessary for treat-
ment than would be predicted by  using the GC/MS
results.  It  was also discovered that some ground
waters that appeared to be treatable by air stripping
from the standpoint of the volatiles were, in fact, not
since other compounds caused frothing which
prevented effective stripping.   Making  these types of
discoveries early in the  remedial process is invaluable
in scoping  potential remedies and  selecting effective
remedies.
   To date, the U.S. and State of  California  govern-
ments have spent approximately  US$110 million on
the site.  The estimated present worth cost of the
                     Preferred Alternative, not including implementation of
                     additional technologies following the planned
                     treatability studies, is  an additional approximately
                     US$186  million.  Cost estimates are assumed  to
                     potentially vary by -30 to +50%.
                        In September 1990, the U.S. EPA signed a Record
                     of  Decision (ROD) to implement some of the items
                     contained in the Preferred  Alternative.  Another
                     Record of Decision will be necessary in the  future to
                     reflect the treatability study outcome and to make final
                     cleanup goals/remedy decisions.  To implement the
                     September 1990 ROD, the U.S. EPA convinced PRP
                     companies to come forward, negotiate and take over
                     implementation of the ROD elements.  Obligations un-
                     dertaken  by the PRP's will require work into the late
                     1990's. Once a final ROD is issued by U.S. EPA, addi-
                     tional negotiations will commence regarding  remedial
                     work that could last for the foreseeable future.

                     9.7  Conclusions
                        Selecting remedies at a complex hazardous waste
                     site requires a methodical approach to successfully
                     move from uncertainty to rational decisions.  It is also
                     necessary to keep the investigative process flexible in
                     order to deal  with inevitable unforeseen circumstan-
                     ces.  As noted in this chapter  as well as in others in
                     this report, applying lessons learned from interim
                     remedies and conducting treatability studies  as early
                     as  possible are also important to effective remedy
                     selection.
                        The remedial efforts conducted over the past  15
                     years  at the Stringfellow Site have  been extremely
                     time-consuming and costly but are, nonetheless, rep-
                     resentative of what can happen when there is the com-
                     bination  of a complex problem,  an aggressive

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                                               Selecting Remedies at a Complex Hazardous Waste Site
environmental regulation, a litigation atmosphere, and
ah aroused public. Cleanup of Stringfellow site-related
contamination is, at best, many years away,  The.coiv
struction of remedies is not the final chapter in clean-
ing up Complex sites such as this; long term monitoring
is required to validate remedial hypotheses and deter-
mine success.  Hopefully, lessons have been and will
continue to be teamed from sites such as Stringfellow
that will be helpful to others in solving hazardous
waste site problems.
REFERENCES
     California Department of Health Services. Stringfellow hazardous waste site feasibility study (Draft Final).
     Sacramento, California, June 30,1988.

     California Department of Health Services. Stringfellow hazardous waste site remedial investigation (Draft
     Final). Sacramento, California, June 1,1987.

     National Oil and Hazardous Substances Pollution Contingency Plan (NCP). 40 CFR 300,55FR8666, March
     8,1990.

     U.S. Environmental Protection Agency. Guidance for conducting remedial investigations and feasibility
     studies under GERCLA (interim final). EPA/540/G-89/004, OSWER Directive 9355.3-01, October 1988.
                                                 107

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                                                                                            10
Conclusions and  Recommendations

Donald E. Banning
United States Environmental Protection Agency
Office of Research & Development, Cincinnati, Ohio 45268
United States

Robert F. Olfenbuttel
Waste Minimization and Treatment, Battelle-Columbus Division
505 King Avenue, Columbus, Ohio  43201
United States
10.1 Introduction
   One of the major accomplishments of this Pilot
Study was that it demonstrated the need to exchange
technical and economic information on contaminated
land and ground water remediation technologies.  The
conclusions are first presented by the specific technol-
ogy chapters in this report, followed by general obser-
vations on remediation, technology transfer and
research needs.  The conclusions are based  on the
case studies, expert speaker presentations, and spe-
cial studies carried out by  Fellows of the Pilot Study.
   In addition to the conclusions, a number of  recom-
mendations were made by the participants in this Pilot
Study to the North Atlantic Treaty Organization's Com-
mittee on the Challenges of Modern Society
(NATO/CCMS) in a separate Summary Report to this
final report. They address potential actions that could
be taken to increase technology development and
technology transfer for site remediation.

10.2 Specific Technology Chapter
     Conclusions
   The following conclusions were reached  on the
basis of the case studies included in the Pilot Study, as
well as related experiences  and observations of the
Study's participants. They include specific technology
needs that could be met through research, develop-
ment and demonstration activities.
10.2.1   Chapter 2: Thermal Technologies

10.2.1.1 Existing high temperature incineration (on-
        and off-site) successfully destroys organic
        contamination; however, not all nations
        allow its use for chlorinated compounds.
   High temperature  incineration is a successfully
documented remediation technology that can be ap-
plied for treatment of sludges, soils, liquids and air ef-
fluents contaminated with various organic constituents.
This technology has been  successfully applied in
many NATO countries, although the thermal treatment
of chlorinated organics is not allowed in at least one
country, The Netherlands,, because of concern for for-
mation of dioxins and/or furans.   The technology is
currently offered by several vendors in many countries
and extensive documentation exists on its costs and
performance.

10.2.1.2 Low temperature thermal desorption is a suc-
        cessful technology for treating volatile and
        semivolatile wastes.
   This technology, which generally operates at
temperatures below 800 "C, allows for the desorption
of volatile and semivolatile constituents from solid and
semi-solid waste. The removed constituents,
entrained in an air stream, are then processed through
a secondary treatment unit, usually a secondary com-
bustion chamber.  Metal and other nonvolatile waste
components come out in the  residual ash stream and

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 Chapter 10	

 can be further processed, if necessary, for final dis-
 posal.

 10.2.2   Chapter 3: Stabilization/Solidification (S/S)
          Technologies

 10.2.2.1 S/S has been proven for the immobilization of
          most inorganics.
    S/S technologies, used as an isolation technology,
 have been shown to be effective with many inorganic
 contaminants, but not with  materials containing or-
 ganic chemicals.

 10.2.2.2 Long term effectiveness data is not available.
    The long term effectiveness of these processes has
 not been proven, especially when they are applied
 under field conditions (weathering,  leaching, structural
 durability, etc.).

 10.2.2.3 Scientifically based S/S leaching tests would
          provide a more easily comparable data
          base than is available today.
    A variety of S/S teaching tests exist today, most of
 which do not have a common technical basis nor  a
 readily understood knowledge of their physico/chemi-
 cal processes. It is, therefore, rarely possible to com-
 pare S/S leaching results due to the lack of data on the
 physfochemical forms of the waste  treated, the chemi-
 cal basis of the S/S mix, the process design  used, and
 the final product pH.  It would be helpful, therefore,  if
 current leaching tests had a more fundamental and
 uniformily understood basis.

 10.2.3    Chapter 4: Soil Vapor Extraction (SVE)
          Technologies

 10.2.3.1  SVE is a viable technology for unsaturated
          zone remediation of volatile and semi-
          volatile contaminants.
   The SVE technology has been demonstrated to be
 viable for the removal of volatile and some semivolatile
 organic compounds from vadose (unsaturated) zone
 soils  that have sufficient air conductivity. These soil
 types typically include porous soils such as  fine- to
 coarse-grained sands. The presence of water in the
 pore spaces  impedes the vapor  transport into the
 gaseous phase. This can be overcome  by lowering
 the ground water level in the area of contamination.
 10.2.3.2  Off-gases can be treated by conventional
          technologies.
   There are  a wide variety of technology options
 available for the treatment of off-gases. These include
 activated carbon, condensation, and thermal destruc-
tion processes.  A number of new technologies are
currently  under development which may provide a
wider range of cost-effective  alternatives for treating
the extracted vapors.
 10.2.4   Chapter 5: Physical/Chemical Extraction
          Technologies

 10.2.4.1  Conventional extractive techniques have
          limited in situ applications.
    In situ extraction techniques will probably play only
 a marginal role in the cleanup of contaminated sites
 due to their limited applicability to soils with high per-
 meability.

 10.2.4.2  Above ground extraction methods are power-
          ful techniques.
    Conventional above ground extraction methods are
 powerful techniques for a large range of soils contain-
 ing heavy metals as well  as organic contaminants, but
 are limited in the soil  size fraction they can effectively
 clean.  One of the major drawbacks of ex situ extrac-
 tion techniques is, however, the production of sludge.

 10.2.4.3  Electroreclamation deserves to be extensive-
          ly investigated.
    Electro reclamation is  a promising new technology
 for the in situ cleanup of clayey soils contaminated with
 heavy metals.  There currently is no other technique
 that shows the  same possibilities.

 10.2.5   Chapter 6: Pump and Treat Ground Water

 10.2.5.1 Pump and treat is a limited technology for
         remediating aquifers.
    The pump and treat operation that started out  in
 1984, as described in this chapter, was intended  to
 remediate  the aquifer  within 5 years.   Although
 remediation has been limited, the pump and treat
 operation continues to perform as a barrier technology
 for inhibiting the further migration of contaminants.
 The case reflects other remediation industry pump and
 treat  experiences that shows, in general, that ground
 water extraction and treatment is not an effective ap-
 proach by itself for the ultimate remediation of aquifers
 to health-based cleanup concentrations.

 10.2.5.2 Air stripping and activated carbon, as il-
         lustrated in the case study Ville Mercier,
         were  only partially effective treatment
         processes.
   The air stripping unit, described in this case study,
was one of the earliest designed systems for treating
 both ferrous iron and volatile organic contaminants  in
ground water. Activated carbon was used with the unit
to capture nonvolatile organics and residual volatile or-
ganics.  However, this approach was found to be only
partially successful in treating contaminated  ground
water.  Subsequently, a pilot-scale study at this site
using  an alternative iron removal process involving dif-
fused air combined with sand filtration, effectively
removed the iron to acceptable levels. This approach,
combined with an alternative  air stripping system
designed to remove  the  most difficult contaminant,
                                                  110

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                                                                  Conclusions and Recommendations
rather than volatile contaminants generally, effectively
reduced the organics to acceptable levels.

10.2.5.3  An ultraviolet radiation/oxidation process
         (Ultrox™) was effective in reducing the con-
         centration of volatile organics in ground
         water to acceptable levels.

10.2.5.4  A precipitation process involving the use of
         lime and sodium sulfide was effective in
         reducing the concentrations of zinc and cad-
         mium to acceptable levels.

10.2.6   Chapter 7: Chemical Treatment of
         Contaminated Soils: APEG

10.2.6.1  The long term stability and behavior of the
         products of partial dechlorination in APEG
         processes require investigation.

10.2.6.2  The combination of thermal pyrolysis and
         APEG treatment applied at Wide Beach,
         New York, USA, was successful in reducing
         PCB concentrations to below target
         cleanup levels.

10.2.7   Chapter 8: Microbial Treatment
         Technologies

10.2.7.1  Bioremediation process scale-up from
         laboratory to the field is difficult.
   The complex physical, chemical and biological na-
ture of the  subsurface  environment makes both
laboratory testing and pilot-scale field evaluations
(treatability studies) essential elements of a successful
approach to  remediation.    Generally, either bench
and/or pilot-scale  studies in the laboratory need to be
followed by pilot and/or full-scale testing in the field.

10.2.7.2 There is a need for both data on oxygen be-
         havior in the subsurface and improved
         methods of providing it for in situ
         bioremediation.
   Since oxygen is both the limiting  and most expen-
sive factor in most applications of in situ bioremedia-
tion, it is important to gain insight  into oxygen supply
and behavior in the subsurface.  Further experimenta-
tion with oxygen delivery techniques is needed.  One
promising technique is the use of soil vapor extraction
methods. The combined effect of vapor extraction and
biodegradation appears  to  provide a method for
achieving remediation of a wide range of organic con-
taminants.

10.2.7.3  There is a need for further research on
         bioavailability and achievable residual con-
         centrations.
   To date, bioremediation  of contaminated soil al-
ways leaves some residual  concentrations of con-
taminants which  may be  acceptable, depending on
site-specific remediation objectives.  These  residual
concentrations can be higher or lower than what is al-
lowed, depending  on a number of possible factors,
particularly the apparent nonavailability of the con-
taminants to indigenous microorganisms. This can be
a restriction for application of biological techniques.
Since bioremediation is often a relative cheap alterna-
tive to other remediation technologies, there exists a
need for further research on bioavailability and over-
coming its impediment to complete site remediation.

10.2.7.4  Soil inoculation has not been proven to en-
         hance in situ bioremediation.
   Although artificially supplied microorganisms  are
expected to have some beneficial effect, this has not
been proven. A major obstruction is that soil microor-
ganisms tend to adsorb onto (soil) particles, and con-
sequently cannot be transported over long distances in
the subsoil.  Another impediment may be the inability
of artifically supplied microorganisms to tolerate real-
world subsurface conditions and/or compete with in-
digenous populations.

10.2.7.5 Permeability is a key factor in applying in situ
         bioremediation.
   Apart from the biodegradability of  typical con-
taminants, permeability is the key parameter which de-
termines the applicability  of in situ biorestoration.
Permeability affects the contact of the microorganisms,
contaminants and the oxygen being supplied to sup-
port the biodegradation process.

10.2.8   Chapter 9: Selecting Remedies at a
         Complex Hazardous Waste Site

10.2.8.1  Remediation should strive to be a complete
         solution.
   Once a remediation sites has been identified, an as-
sessment of critical problems  must be made. Impacts
from the site on the environment and health need to be
addressed and relevant cleanup goals established.
Remediation efforts can be  phased and monitored so
that problems are solved in a timely fashion.  Once the
planned remediation actions have been completed,
long term monitoring may be needed to determine if
the remedial actions have been successful overtime.

10.2.8.2 Treatability studies must be conducted as
         early as possible for effective remedy selec-
         tion, and technologies should be judged by
         their overall performance.
   Conducting treatability studies as early as possible
is essential to effective selection of remedies.  The
consequence of not doing them until late in the  selec-
tion process may be unnecessary delays in construct-
ing remedies.  The consequence of not doing them at
all may  be  ineffective remedies.  In addition, tech-
nologies should be judged  by their overall perfor-
mance,  including generation of new waste streams
                                                  111

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  Chapter 10	

  and long term performance, and not by cleaning
  results only.

  10.2.9   Appendix: In Situ Vitrification

  10.2.9.1 Vitrification is a promising technique for treat-
          ing mixed organic and inorganic wastes.
    Heavy metals combined with organic contaminants
 still pose problems in the present treatment schemes
 and treatment trains  may be  needed to address this
 problem. It is not expected that this will change in the
 future. Vitrification combines the advantages of a ther-
 mal process  (destroying the organic contaminants)
 with immobilization of the inorganics.  Furthermore, it
 leads to a final product showing a considerable resis-
 tance to leaching.

 10.3  General Conclusions
    In  addition to  the specific technology  area con-
 clusions discussed in Section  10.2, the participants of
 the Pilot Study reached the following conclusions that
 apply to most if not all of the case studies,  as well as
 conclusions derived from special studies of the Fel-
 lows and guest expert speakers to the Pilot Study.

 10.3.1    Remediation

 10.3.7.1  Energy efficiency practices influence plant
          design and, therefore, processing costs in
          different countries.
    Energy costs in the  United States (U.S.) are very
 much  lower than those in Europe.  This may have in-
 fluenced plant design, since one might expect  more
 attention to have been paid to energy efficiency in
 plants designed in, for example, Germany, than those
 designed in the U.S.  Thus, simply multiplying energy
 costs fora plant operating in the U.S. to give an energy
 cost for a similar plant in Europe may be misleading
 (leading to a high estimate of operating costs) because
 the European designer would take care not to use so
 much energy (but possibly have a higher capital cost,
 in consequence).  Similar considerations might apply
 to attitudes to how labor-intensive operation of a plant
 is.
   Therefore, care should be taken when comparing
 costs of different technologies, and when considering
 the application of a technology in a country other than
 that in which it was developed.  Allowance must be
 taken of variable factors such as energy and labor
 costs,  which will  not  only influence operating costs
 directly, but  also plant design  and associated capital
 costs.

 10.3.1.2  Treatment and permanent solutions are
         preferred.
   Remediations based on technologically permanent
solutions are preferred. Successful remediation re-
quires  treatment of the  waste source.  Containment
 technologies may only provide temporary solutions
 leading to the potential need for additional remediation
 at a future date.

 10.3.1.3  Integrated technology treatment systems are
          needed for site remediation.
    The complexity of contaminated sites and multiple
 pollutants requires a multidisciplinary use of engineers
 and scientists to solve the problems.  Similarly, multi-
 technology solutions offer the potential to be more ef-
 fective in cleaning up sites than the historical use of
 single  technology systems.  A combination  of tech-
 nologies can facilitate the preprocessing and treatment
 of contaminated soils and ground water, as  well the
 postprocessing of residuals.
    Modular designed integrated treatment trains  can
 provide system flexibility in optimizing specific process
 units to treat different contaminants of varying con-
 centrations within various media.  This modular arran-
 gement also allows the addition or withdrawal of
 processing units within the system, as needed, as well
 as allowing users the opportunity to insert  and
 evaluate new/upgraded technologies as they become
 available.  Modular design requires additional up-front
 design but may result in lower capital  and operating
 costs than conventional one-technology designs.
    This integrated systems approach also applies to
 situations where there  are multiple areas  of con-
 tamination on a given "site" and where it makes more
 sense  to use specific technologies on each area,
 rather than trying to make one technology solve all of
 the contamination problems,  the  challenge is to  get
 away from the traditional idea of one technology "fits
 all."

 10.3.1.4  Field treatability/pilot studies should be con-
          ducted for each technology under con-
          sideration, under the range of potentially
          applicable site field conditions.
    This conclusion of  the first NATO/CCMS study on
 contaminated land is reaffirmed by this NATO/CCMS
 Pilot Study. The complex physical and chemical na-
 ture of the subsurface environment makes both
 laboratory testing and  pilot-scale field evaluations
 (treatability studies) essential elements of a successful
 approach to remediation.  Generally,  either bench
 and/or pilot-scale studies in the  laboratory need to be
 followed by pilot and/or  full-scale testing in the field.
 These treatability studies should indicate if the technol-
 ogy is applicable to the waste and provide information
 on the optimal level of treatment effectiveness that the
technololgy can achieve.  Bench- and pilot-scale reac-
tor  evaluations must be  tailored to each specific  ap-
plication in order to obtain the  maximum amount of
credible data at minimum costs and establish the basis
for follow-on field evaluations.
                                                  112

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                                                                   Conclusions and Recommendations
 10.3.1.5  Technology scale problems need to be ad-
          dressed in design and testing.
    Care must be taken in translating technologies from
 bench to pilot to demonstration or full-scale so that all
 aspects of the scale up are taken into account (e.g,
 reactor design, materials and residuals handling).
    The scale up of pilot-scale systems to full-scale
 operating systems can often result in unforeseen dif-
 ficulties which  need to be addressed in the design.
 Careful consideration  is needed of  how design vari-
 ables (e.g., wall effects, mixing efficiencies, flow pat-
 terns, fugitive emissions, retention times) can change
 as a result of system scale up. To overcome some of
 these  problems, particularly for technologies  which
 have not yet been widely used, operating flexibility can
 be built into the system by modular design, by provid-
 ing the ability to vary feed rates and by providing surge
 capacity at various points throughout the system. It is
 important that adequate design attention be paid to all
 unit operations and that vendors of similar equipment
 are contacted to obtain information on scale up
 problems.  However,  care must be exercised when
 using  vendor information because frequently their
 scale up  procedures are based  more on experience
 and testing of  a  particular waste using proce-
 dures/protocols that they have developed.  Although
 these testing procedures may work, the design prin-
 ciples  involved may not be fully developed or under-
 stood.

, 10.3.1.6  A mass balance  approach  to remediation is
          desirable.
    For all projects, remediation design should be
 based on a firm understanding of the mass and types
 of pollutants involved, the current location of all of the
 mass remaining in the subsurface, and the chemical,
 physical  and biological processes controlling the
 movement and fate of the  mass from the subsurface.
 Usually, however, knowing any one of these is rare for
 in situ remediation, let alone all of them.   While it is
 desirable to conduct all  remediation from a mass
 balance perspective, experience shows that it will be
 practically impossible to obtain a true mass balance in
 either  in situ or above  ground processes because of
 the heterogeneity  of the subsurface environment,
 limitations of investigation tools and current technology
 to accurately determine and/or predict the fate and be-
 havior of the contaminants, such as their direction and
 rate of  movement, spacial  distribution and concentra-
 tion.
    Nevertheless, all technology application evalua-
 tions should be planned and  conducted on a mass
 balance basis since it provides a  rational and fun-
 damental structure  for  asking specific questions and
 obtaining specific information that  is necessary for
 determining contaminant fate and behavior,  for
 evaluating and selecting  treatment options, and for
monitoring treatment effectiveness at both laboratory
and field scale sized operations.

70.3.1.7 Technology remedies that transfer con-
         taminants from one media to another
         should be avoided, if possible.
   Remediation activities sometimes transfer con-
tamination from one media, such as contaminated soil,
to another media (e.g., air). Therefore, it is advisable
to review all  the pollutant emission pathways which
could result from remediation activity.  If any emission
is possible, its impact on treatment effectiveness and
surrounding media should be evaluated.  Under such
scrutiny, some technologies may be rejected because
emission control and/or the  additional treatment
needed to lessen its impact on other media may
change the feasibility of the overall  planned remedia-
tion effort.

10.3.1.8 All remediations require proper operation and
         management.
   Implementing technologies that have been proven
using field demonstration-scale  treatability studies is
not enough to ensure success of the remediation ac-
tivities. The overall effectiveness of a remediation
scheme, which may include  many interrelated ele-
ments of  civil engineering works and soil and/or
ground water cleanup technologies, will depend heavi-
ly on the care with which the individual processes are
operated in the field; site and operating conditions
may change over time and skilled people are needed
to adjust technologies to these changes and/or remove
them from operation if they don't meet expectations.
Similarly, a strong quality assurance program needs to
be in place and activities carried out by a dedicated,
effective management team.

70.3.1.9 Long-term monitoring of permanent remedia-
         tion may be necessary to ensure that
         cleanup goals are met.
   Construction of soil and ground water remedies is
not the endpoint for determining whether environmen-
tal protection concerns have been satisfied.   Com-
prehensive, long term monitoring is essential to assure
that the required remedies are implemented, operated
and maintained, and ultimately are successful. This, in
turn, requires that long term oversight be conducted by
well trained personnel.

10.3.1.10 Basic records should be preserved.
   A major challenge in evaluating current and emerg-
ing technology effectiveness to that used in the past is
that there is usually insufficient data available on which
to base an evaluation, particularly for in situ remedia-
tion activities. Therefore, it will be advantageous to fu-
ture remediation planners  if records of  site
investigations and associated remediation  activities
are preserved for future reference and evaluation.
                                                  113

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 Chapter 10
 10.3.2   Technology Transfer

 10.3.2.1 Uniform data collection Is needed.
   There is a critical need for the establishment/use of
 a uniform  data  reporting  methodology that can be
 universally applied.  Various data base systems are
 available and in use.  However,  input of consistent
 data into these systems and easy  access to them will
 benefit all users. One particularly critical area of infor-
 mation needed  in these data bases is the cleanup
 standards used  at each site since these provide the
 basis  (remediation goal)  upon which technologies
 have been shown to be effective or not. The cleanup
 standards are also important since there are no current
 internationally agreed on standards and those ap-
 plicable in one nation or state may not be pertinent in
 another.

 10.3.2.2 Independent technology evaluations are
         needed for effective technology transfer.
   Since reporting systems and data bases are only
 as good as the data in them, a major challenge to the
 remediation community is  obtaining  reliable, credible
 data in a timely fashion.   Projects  in the field of
 remediation techniques for contaminated soil are so
 different in approach, execution and  demands for
 cleanup, that comparison of technology and  results is
 difficult if not impossible without organized, consistent
 preplanned evaluations.
   To  overcome these difficulties, demonstrations of
 technologies are needed that are well designed from a
 mass balance point of view and objectively monitored,
 analyzed and reported on by those who do not have a
 vested interest in the technology itself. When properly
 designed, executed and documented, such field trials
 and demonstrations on a  variety of site and ground
 water matrices will not only verify the strengths and
 limitations of technology but also  provide a credible
 basis for technology transfer and application. These
 actions require a serious  commitment of support by
 governments to  do so because no private organiza-
 tions will have the capability to do this in a concerted,
 consistent manner.
   This NATO/CCMS Pilot Study  has shown the
 benefits to  be gained  from such well designed,  sup-
 ported, and independently monitored field scale
 demonstrations for the evaluation  of soil and ground
 water treatment technologies.  The participants of fu-
ture NATO/CCMS Pilot Studies of  a  similar character
would further enhance the utility of  future candidate
 demonstrations  by providing guidance on project
 design and information needs which would maximize
their value as case studies.

 10.3.2.3 The NATO/CCMS network is an important
         source of information.
   In order to share the successes and failures of
technologies used within the hazardous waste treat-
 ment arena, continued, positive interactions between
 NATO members are needed.  Often successful  ap-
 plications of technologies are addressed  in public
 forums  and the literature with little attention paid to
 those efforts which were not totally successful or that
 were outright failures.  It is more likely that the free
 exchange of information and technology developments
 will encourage all aspects of environmental research
 and development when there are avenues  available
 which promote interaction and communication such as
 the NATO/CCMS Pilot Study Group. It has provided a
 valuable network for information exchange that other-
 wise would not have been available.

 10.3.3   Research

 7 0.3.3.1 There is a continuing need for development
         of new technologies and use of common re-
         search protocols.
   The  technical  limitations and or cost of present
 technologies  indicate that ongoing research and
 development (R & D) is needed to improve the effec-
 tiveness of current technologies and provide new treat-
 ment alternatives.  There is also  a need for the
 development of guidance to aid in the design and con-
 duct of research,  pilot-scale, and demonstration
 studies  in order to  maximize their value to potential
 users.
   As in the case of remediation, it is essential in all
 research studies on treatment or contaminant tech-
 nologies that all materials used are fully characterized,
 in terms of their chemical, physical, mineralogical and
 microbial composition.

 10.3.3.2 Scientific understanding of processes is es-
         sential in order to ensure against formation
         of harmful end products.
   As in the case of remediation activities, processes
 can be shown to be "effective" by relatively simple test-
 ing (e.g., showing that the targeted contaminant
 detected in the feed material is no longer present in the
treated material), but it is not a sufficient basis for  ac-
 ceptance of a treatment technology since toxic inter-
 mediates, byproducts and residuals may be formed.
Therefore, a thorough understanding of the treatment
process mechanisms involved is required in order to
avoid such undesirable occurrences.

 7 0.3.3.3 Standardization of analytical methods is
         needed.
   There is a lack of standardization of analytical
methods used within the worldwide hazardous waste
community  and, in fact, within each  country.  As a
result, there can be confusion about what  the data
means and the conditions under which the data was
obtained and analyzed.  Under such  circumstances,
data can be misinterpreted or appear inconclusive.  A
level of confidence in the interpretation of data can be
established underworld wide acceptable standardized
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                                                                 Conclusions and Recommendations
analytical methods.  Concurrently, greater attention is
needed in the area of experimental design and in es-
tablishing the hypotheses which define what data are
needed and the quality of that data, which in turn es-
tablishes the analytical methods. Then data collected
can and should be interpreted in view of the questions
it was set out to answer as defined by the experimental
design.  In addition, it would be beneficial to the haz-
ardous waste community if qualified organizations had
ongoing programs to both evaluate new analytical
techniques and update the analytical standards cor-
responding to use of those techniques.

10.3.3.4 Techniques are needed to remove contamina-
         tion beneath urban structures without sig-
         nificant disturbance to ongoing activities.
   The  remediation of  contaminated sites in urban
areas raises a particular need  for in situ technologies
that can be applied around and beneath buildings, in-
frastructure and services, with  minimal disturbance to
artifacts or to the environment.

10.4 Recommendations
   The following recommendations were made by the
participating members to the NATO/CCMS.

10.4.1   CCMS is invited by the Pilot Study Director to
         commend this report to NATO Council for
         approval.
   All of the participants in this phas'e of the study
need to be commended for their professionalism, tech-
nical  expertise and cooperation.   The Pilot Study
Director particularly thanks the  two Co-pilot Countries,
Germany and The  Netherlands for their  assistance.
All of the Fellows need to be  complimented  on their
technical quality and input to the study.   The Expert
Speaker activities within the study were a stellar suc-
cess in providing an intellectual stimulus to all of their
participating Countries.  Over and above the technical
successes of the study, a camaraderie was estab-
lished between the participating country repre-
sentatives that led to many spinoff activities between
different Countries and  in different areas  of environ-
mental technologies.  Professional enhancement and
recognition increased for many of  the participants.
Conference participation and publications resulting
from this  Study were  numerous throughout both
Western Europe and North America and these proved
to be valuable technology transfer activities that
provided information being generated within the Study
to the rest of the environmental community in a timely
manner.
   Therefore, the NATO/CCMS is invited to commend
this Final Report to  member governments and draw
their attention to the technical information and the Con-
clusions and Recommendations contained  herein.
 10.4.2   Continue the NATO/CCMS Pilot Study to in-
         clude reporting on the field demonstration
         of technologies and on new/emerging tech-
         nologies.
   Ongoing problems with waste management prac-
tices in all countries continue the need for advancing
the state-of-the-art in remediation technologies.  The
current phase of the NATO/CCMS Pilot Study on this
topic provided an excellent forum for technology ex-
posure and technology transfer among countries.
Therefore, it is recommended that this Study continue
into a second phase.  Since in situ and on-site
remediation usually takes time, this second phase will
enable member countries to  see how well the tech-
nologies perform during complete remediation ac-
tivities.  It will also enable  current members, and
additional countries that haive expressed an interest in
the Study, to  take advantage of data from new field
demonstrations.  In addition,  it  will provide them the
opportunity to report  on developments in national
legislation and regulations, as well as exchange tech-
nical information on ongoing work in the development
of new technologies, and potentially avoid duplication
of research projects.

 10.4.3   Continuation of the current NATO/CCMS Pilot
         Study should also include cleanup criteria,
         project design methodologies, and
         documentation of completed remediations.
   The continuation of this NATO/CCMS Pilot Study
can advance the state-of-the-art in remediation tech-
nologies by including  related areas  of interest to
decisionmakers.  These include an examination of
cleanup  criteria used  by various countries,
methodologies used in the design of research, pilot
and field  demonstration projects,  and documentation
of completed  remediations that examines  suc-
cess/failure, costs, field problems, etc.

10.4.4   Encourage participation of NATO and
         nonNATO countries in the continuation
         study.
   Past participation has been a two-way reward for
participating Pilot Study mesmbers. Not only have par-
ticipants learned but have also shared their experien-
ces with others.  The sharing of knowledge from the
current Pilot Study, coupled with an increased ex-
change of information with new participants, can en-
hance technology transfer and remedial  action
progress.

10.4.5   NATO/CCMS should encourage more active
         participation by all member countries.
   The NATO/CCMS should  encourage membership
within Pilot Studies, whether as full participants or as
observers, by as many countries as possible. It should
draw the  attention of member countries to the  way in
which membership can open the doors for researchers
and regulators, within and outside central government,
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Chapter 10
and to high quality technology exchange programs. It
should, therefore, encourage member countries to
adopt formal observer status, even if the country itself
wishes to have only minimal active participation at the
official level. The NATO/CCMS is  also requested to
encourage member countries to give greater publicity
to the activities of Pilot Study Groups and to the related
Fellowship program.
10,4.6   Encourage participation under the NA TO
         Science Committee to establish a scientific
         program and advance study institute for soil
         and ground water contamination issues.
   There are significant deficiencies in our fundamen-
tal understanding of subsurface soil and ground water
systems and the complicated interactive processes
which  control  contaminant behavior and fate within
those systems. Without profound scientific advances
In our understanding of these phenomena, site inves-
tigation and  treatment technologies will likely be slow,
risky, expensive, and poorly effective.
   Therefore, the NATO Scientific  Committee is  en-
couraged to establish  a  special scientific program for
addressing fundamental  gaps  in understanding these
phenomena.  Such  a  program should include a
Science Fellowships Programme, an Advanced Study
Institute, Advanced Research Workshop(s),  as well as
collaborative research grants, including both  NATO
and nonNato researchers.

70.4.7   NATO/CCMS should support the transfer/ap-
         plication of results of current study through
         workshops and seminars within NATO and
         nonNATO countries.
   Mindful of the contaminated land problems  known
to exist in certain nonparticipant NATO countries, and
In many nonNATO countries, including those in East-
em and Central Europe, the Pilot Study Group recom-
mends that NATO arrange a series of workshops and
seminars specifically in those places, in order to aid in
the dissemination of the results of the present study.
 10.4.8   The NATO/CCMS should encourage annual
         technology transfer reports from each of its
         individual pilot studies.
   This Pilot Study showed the value to member
countries of frequent publications and verbal presenta-
tions on the status and  results  of the its activities.
Therefore,  all Pilot Study  Directors and technical par-
ticipants are encouraged  to publish  an annual report
on the progress of their Study in either international
conferences or journals, or both.  Publication in both
Europe and North America is encouraged.

 10.4.9   Create a more formal interface of the continued
         pilot study with OECD, EC and other inter-
         national groups.
   Throughout the first phase of the pilot study there
was minimum involvement/representation from other
international groups such as OECD and EC at the
meetings.  On two occasions the Pilot Study Director
visited OECD and conducted a briefing for Waste
Policy Management officials.  The EC attended and
presented at one meeting over the five year period.  It
is recommended that the NATO/CCMS lend its  sup-
port to the various interested Pilot Studies to formalize
and  increase the participation of other international
groups.

 10.4.10  A budget for writing the final report should be
         established to encourage final report
         preparation.
   Researchers generally have a limited budget for
activities not directly involving their regular work. At
present, the preparation of final reports is a spare time
activity. Furthermore, not all studies  provide the infor-
mation necessary for a detailed final report and addi-
tional information acquisition is needed in some cases.
Because contributions to the NATO/CCMS study are
not directly profitable to the institution in which the re-
searchers are employed, it is desirable that NATO pro-
vide  a financial incentive to employers to give
contributors time to work on NATO/CCMS reports
during regular working hours.  This would also make
the  acquisition of additional information (telephoning,
writing letters) easier.
                                                           • U.S. GOVERNMENT PRINTING OFFICE, 1993 -750 -002/ 609S"t
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