United States          Office of Solid Waste       SW-872
             Environmental Protection      and Emergency Response     September 1982
             Agency            Washington DC 20460      Revised Edition
x°/EPA       Guide to the Disposal
             of Chemically  Stabilized
             and Solidified Waste

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      GUIDE TO THE DISPOSAL OF CHEMICALLY
       STABILIZED AND SOLIDIFIED WASTE
                      by

           Environmental Laboratory
U.S. Army Engineer Waterways Experiment  Station
         Vicksburg, Mississippi   39180
   Interagency Agreement No. EPA-IAG-D4-0569
                Project Officer

              Robert E. Landreth
  Solid and Hazardous Waste Research Division
  Municipal Environmental Research Laboratory
            Cincinnati, Ohio  45268
   y <;   •".-.'"•"   ,,'  ! T;,,:cc;ioii  Agency
   i-   ' •  '•'
   ::,,.  ,             "' '-'."•; x&
   Caicuo,  nti.'.ulj   6wb04
  MUNICIPAL ENVIRONMENTAL RESEARCH LABORATORY
      OFFICE OF RESEARCH AND DEVELOPMENT
     U.S. ENVIRONMENTAL PROTECTION AGENCY
            CINCINNATI, OHIO  45268

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                                 DISCLAIMER

      This report has been reviewed by the Municipal  Environmental Research
Laboratory, U.S. Environmental Protection Agency,  and approved for publica-
tion.  Mention of trade names or commercial products  does  not  constitute
endorsement or recommendation for use.
               r>. i
               . . "f--.- '•'--. f. .
                             irv
                                     ii

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                                  FOREWORD
     The Environmental Protection
public and governmental concern about
and welfare of the American people.
land are tragic testimony to the
The complexity of the environment
require a concentrated and integral
                                  Agency was created because of increasing
                                      the dangers of pollution to the health
                                     Noxious air, foul water, and spoiled
                                 deterioration of our natural environment.
                                      the interplay between its components
                                   ed attack on the problem.
    and
                                 the
     Research and development is
it involves defining the problem,
lutions.  The Municipal Environmental
improved technology and systems to
the solid and hazardous waste
ity sources; to preserve and treat
minimize the adverse economic,
tion.  This publication is one of
communications link between the
                               social
                                  the
     This study examines procedures
wastes for disposal, including physical
lines options for ultimate disposal
ify or chemically stabilize industrial
preservation of human health and tbje
isolate toxic materials.
       first necessary step in problem solution;
    treasuring its impact, and searching for so-
        Research Laboratory develops new and
     prevent, treat, and manage wastewater and
pollutant discharges from municipal and commun-
     public drinking water supplies; and to
         health and aesthetic effects of pollu-
        products of that research—a vital
  res|earcher and the user community.
                                    for the treatment of hazardous industrial
                                        and chemical test procedures and out-
                                    of treated wastes.  Techniques that solid-
                                       waste products may contribute to the
                                     environment by helping us immobilize and
                                      FRANCIS T. MAYO
                                      Director
                                      Municipal Environmental Research
                                        Laboratory
                                     iii

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                                  PREFACE

     The land disposal of hazardous  waste  is  subject to the requirements
of Subtitle C of the Resource Conservation and Recovery Act of 1976.  This
Act requires that the treatment,  storage,  or  disposal of hazardous wastes
after November 19, 1980 be carried out  in  accordance with a permit.  The
one exception to this rule is that facilities in existence as of November
19, 1980 may continue operations  until  final  administrative disposition is
made of the permit application (providing  that the  facility complies with
the Interim Status Standards for  disposers of hazardous waste in 40 CFR
Part 265).  Owners or operators of new  facilities must apply for and receive
a permit before beginning operation  of  such a facility.

     The Interim Status Standards (40 CFR  Part 265) and some of the adminis-
trative portions of the Permit Standards (40  CFR Part 264) were published
by the Environmental Protection Agency  in  the Federal Register on May 19,
1980.  The Environmental Protection  Agency published interim final rules
in Part 264 for hazardous waste disposal facilities on July 26, 1982.
These regulations consist primarily  of  two sets of  performance standards.
One is a set of design and operating standards separately tailored to each
of the four types of facilities covered by the regulations.  The other
(Subpart F) is a single set of ground-water monitoring and response require-
ments applicable to each of these facilities. The  permit official must
review and evaluate permit applications to determine whether the proposed
objectives, design, and operation of a  land disposal facility will comply
with all applicable provisions of the regulations (40 CFR 264).

     The Environmental Protection Agency is preparing two types of documents
for permit officials responsible  for hazardous waste landfills, surface
impoundments, land treatment facilities and piles:  Draft RCRA Guidance
Documents and Technical Resource  Documents.  The draft RCRA guidance
documents present design and operating  specifications which the Agency
believes comply with the requirements of Part 264,  for the Design and
Operating Requirements and the Closure  and Post-Closure Requirements
contained in these regulations.  The Technical Resource Documents support
the RCRA Guidance Documents in certain  areas  (i.e., liners, leachate
management, closure, covers, water balance) by describing current techno-
logies and methods for evaluating the performance of the applicant's design.
The information and guidance presented  in  these manuals constitute a
suggested approach for review and evaluation  based  on good engineering
practices.  There may be alternative and equivalent methods for conducting
the review and evaluation.  However, if the results of these methods differ
from those of the Environmental Protection Agency method, they may have to
be validated by the applicant.
                                    iv

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     In reviewing and evaluating the permit  application, the permit official
must make all decisions in a well defined  and  well  documented manner.  Once
an initial decision is made to issue or deny the  permit, the Subtitle C
regulations (40 CFR 124.6, 124.7 and 124.8)  require preparation of either a
statement of basis or a fact sheet that discusses the  reasons behind the
decision.  The statement of basis or fact  sheet then becomes part of the
permit review process specified in 40 CFR  124.6-124.20.

     These manuals are intended to assist  the  permit official in arriving
at a logical, well-defined, and well-documented decision.  Checklists and
logic flow diagrams are provided throughout  the manuals to ensure that
necessary factors are considered in the decision  process.  Technical data
are presented to enable the permit official  to identify proposed designs
that may require more detailed analysis because of  a deviation from suggested
practices.  The technical data are not  meant to provide rigid guidelines
for arriving at a decision.  The references  are cited  throughout the manuals
to provide further guidance for the permit officials when necessary.

     There was a previous version of this  document  dated September 1980.
The new version supercedes the September 1980  version.

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                                  ABSTRACT

     Stabilization/solidification of Industrial waste is a pretreatment
process that has been proposed to insure safe disposal of wastes containing
harmful materials.  This manual examines the regulatory considerations,  cur-
rent and proposed technology, testing procedures and design of landfills,
and other options involved in disposal systems using stabilization/
solidification of wastes.  A summary of the major physical and chemical
properties of treated waste is presented.  A listing of major suppliers  of
stabilization/solidification technology and a summary each process is
included.
                                     vi

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                                  CONTENTS
Foreword	   ill
                                                                 a
Preface	    iv
Abstract	    vi
Figures	    ix
Tables 	    x
Acknowledgment 	    xi

   1.  Introduction	    1
         1.1  Purpose	    1
         1.2  The Terminology of Waste Solidification/Stabilization   .  .    1
         1.3  Legislative Background  	    2
         1.4  Characteristics of Wastes for which Stabilization/
              Solidification are Effective and Economical   	    6
         1.5  Delisting Treated Hazardous Waste Products 	    7
   2.  Waste Stabilization/Solidification Technology  	    10
         2.1  Current Waste Stabilization/Solidification Technology.  .  .    10
         2.2  Cement-Based Processes  	    12
         2.3  Pozzolanic Processes  (Not Containing Cement)  	    15
         2.4  Thermoplastic Techniques (Including Bitumen,  Paraffin
              and Polyethylene)	    16
         2.5  Organic Polymer Processes	    18
         2.6  Surface Encapsulating Techniques (Jacketing)  	    19
         2.7  Self-Cementing Processes 	    20
         2.8  Classification and Production of Synthetic Minerals or
              Ceramics	    22
         2.9  Summary	    23
   3.  Properties of Stabilized/Solidified Wastes	    26
         3.1  Characterizing Wastes to be Treated	    26
         3.2  Requirements for Ideal Waste Stabilization/Solidification.    26
         3.3  Compatability of Wastes and Treatment Additives	    27
         3.4  Testing the Physical Properties of  Stabilized Wastes  ...    30
         3.5  Chemical Leach Testing of Stabilized Wastes	    40
         3.6  Effects of Biological Attack on Treated Wastes  	    43
         3.7  Effects of Curing and Aging Processes on Treated Material.    44
         3.8  Economic Considerations of Treatment Options  	    44
   4.  Assessment of Current Data on Physical and Chemical  Properties
       of Treated Wastes	    49
         4.1  Existing Data on Physical Properties of Treated Wastes  .  .    49
         4.2  Existing Data on Chemical Properties of Treated Wastes  .  .    50
         4.3  Correlation of Physical and Chemical Properties	    54
         4.4  Interpretation of Physical and Chemical Data	    54
                                     vii

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                                  CONTENTS
   5.  Design Considerations for Solidified and Stabilized Waste
       Disposal Facilities 	    56
         5.1  Special Considerations for Handling and Disposal of
              Stabilized/Solidified Wastes  	    56

         5.2  Design Factors for Hazardous Waste Landfills 	    57
         5.3  Use of Land Treatment of Biodegradable Industrial Wastes  .    58
         5.4  Operation and Management of Disposal Facilities for
              Treated Wastes 	    59

   6.  Stepwise Evaluation of Stabilized/Solidified Wastes 	    62
         6.1  Step 1.  Evaluation of Hazardous Nature of Treated Waste  .    62
         6.2  Step 2.  Determination of Maximum Toxic Hazard Under
              Normal Conditions	    64
         6.3  Step 3.  Determination of Physical Integrity and
              Durability	    64
         6.4  Step 4.  Estimation of Leaching Loss Over a Long Term.  .  .    65
         6.5  Step 5.  Assessment of Land Burial Sites	    66
         6.6  Step 6.  Evaluation of Monitoring and Closure Programs  .  .    66
         6.7  Step 7.  Quality Control of Waste Treatment	    69
         6.8  Step 8.  Evaluation of Aged Material	    69
         6.9  Permitting and Operating Experience	    69

Appendices

   A.  Sources of Fixation Technology	    72
   B.  Proposed Uniform Leach Procedure	    97

Glossary	   108
                                    viii

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                                   FIGURES

Number                                                                    Page

2-1     Examples of solidified electroplating waste  	    11

2-2     Close-up of plastic-jacketed electroplating waste  	    21

3-1     Compression testing of plastic-jacketed wastes	    34

3-2     Typical solidified waste test specimens after 4 wet-dry test
          cycles	    36

6-1.    Percent of constituents remaining in barrel-sized, cylindrical
          ingots (90 cm long x 55 cm diam.) of solidified  waste over
          100 years of.leaching for wastes having diffusivities of
          10   to 10    cm /sec	    67

6-2     Percent of constituent remaining in semi-infinite  slab  (10 cm
          thick) of solidified waste over 100 years of leaching for
          wastes having diffusivities of 10   to 10    cm  /sec  ....    68
                                      ix

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                                   TABLES

Number                                                                    Page
  1-1   Treatment Codes for EPA Hazardous Waste Manifests  	      3

  1-2   Some Attributes of Commonly Available Waste Treatment Options  .      4

  3-1   Reactions Occurring Between Incompatible Wastes  	     28

  3-2   Compatibility of Selected Waste Categories with Different
          Waste Solidification/Stabilization Techniques  	     31

  3-3   Long-Term Chemical Resistance of Organic Polymers  (Resins)
          Used in Solidifications	     32

  3-4   Standard Tests of Physical Properties   	     33

  3-5   Typical Results from Physical Testing of Stabilized and
          Untreated Industrial Wastes 	     37

  3-6   Present and Projected Economic Considerations  for  Waste
          Stabilization/Solidification Systems	     46

  4-1   Results of Physical Property and Leaching Tests Made by  Sludge
          Stabilization Vendors 	     51

  4-2   Relationship Between Percent Solids, Unconfined Compressive
          Strength and Cement Content of a Chemically  Stabilized
          Sludge	     53

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                               ACKNOWLEDGMENTS

      This manual was prepared by the Environmental Laboratory  (EL)  of  the
U. S. Army Engineer Waterways Experiment Station  (WES) under  sponsorship  of
the Municipal Environmental Research Laboratory,  U. S. Environmental Protec-
tion Agency.

      The contributing authors are Dr. Philip G.  Malone, Dr.  Larry W. Jones,
and Robert J. Larson.  Mr. Norman R. Francingues  reviewed  the manuscript  and
provided valuable criticism.  The abstracts presented  in Appendix B  are
available through the efforts of the many companies that responded to in-
quiries and submitted technical information for inclusion  in  this publica-
tion.  The project was conducted under the general supervision  of Dr. John
Harrison, Chief, EL; Mr. Andrew J. Green, Chief,  Environmental  Engineering
Division; and Mr. Norman R. Francingues, Jr., Chief, Water Supply and Waste
Treatment Group.

      The guidance and support of Mr. Robert E. Landreth,  Mr. Norbert B.
Schomaker and the Solid and Hazardous Waste Research Division,  Municipal
Environmental Research Laboratory, U. S. Environmental Protection Agency  are
gratefully acknowledged.  The diligent and patient efforts of Ms. Billie
Smith and the staff of the EL Word Processing Section  are  also  gratefully
acknowledged.  Illustrations and figures were prepared by  Mr. Jack H.
Dildine.  The Director of WES during the course of this work  was COL Nelson
P. Conover, CE.  Technical Director was Mr. F. R. Brown.
                                     xi

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                                   SECTION  1

                                 INTRODUCTION
1.1  PURPOSE

     The purpose of this manual is to provide  guidance  in  the  use  of  chemi-
cal stabilization/solidification techniques for  limiting hazards posed  by
toxic wastes in the environment, and to assist in  the evaluation of permit
applications related to this disposal technology.  The  document addresses
the treatment of hazardous wastes for disposal or  long-term  storage and
surveys the current state and effectiveness of waste-treatment technology.
This guide provides the background information needed for  waste generators
and regulatory officials to determine the testing  program  and/or product
information necessary for them to make the best  engineering  judgments con-
cerning the long-term effectiveness in site-specific conditions.

     The manual assumes the permit writer and/or other  readers are familiar
with the latest regulations concerning the disposition  and disposal of  haz-
ardous and nonhazardous bulk-liquid and semisolid  sludges  and  wastes  in
secure and sanitary landfills.  Some familiarity with general  soil charac-
teristics, water balance, climatic conditions, and fundamentals of leachate
generation would also be helpful to the manual user.

1.2  THE TERMINOLOGY OF WASTE SOLIDIFICATION/STABILIZATION

     The current interest in the technology of waste stabilization/solidifi-
cation in this country reflects recent social and  political  priorities
placed on environmental protection.  Current terminology in  the field
includes new terms and terms borrowed from other fields which  are  given new
and specific meanings.  As a matter of necessity,  the following terms are
used in this manual with the meanings as noted below.   These words have not
been officially defined by EPA as have those appearing  in  the  glossary  at
the end of the manual.

     "Solidification" and "stabilization" as used  here  both  refer  to  treat-
ment systems which are designed to accomplish one  or more  of the following:
(a) improve handling and physical characteristic of the waste, (b) decrease
the surface area across which transfer or loss of  contained  pollutants  can
occur, (c) limit the solubility of, or to detoxify, any hazardous  con-
stituents contained in the wastes.  Solidification implies that these re-
sults are obtained primarily, but not necessarily  exclusively, via the
production of a monolithic block of treated waste  with  high  structural

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integrity.  Stabilization techniques are those which have their beneficial
action primarily by limiting the solubility or by detoxifying  the waste  con-
taminants even though the physical characteristics of the waste may  or may
not be changed and improved.  Stabilization usually involves addition of
materials that ensure the hazardous constituents are maintained in their
least soluble and/or toxic form.

     The term "fixation," has fallen in and out of favor but is widely used
in the waste treatment field as generally meaning any treatment system which
solidifies and/or stabilizes the waste as just described above.  This is the
restricted use of the term as it is employed in this document.  Other deriva-
tives of this term such as "to fixate" (or "fixated" waste), to "fix"  (or
"fixed" waste), and even "fixalated" are not used in this manual.

     The term "treatment" has been legally defined by the EPA.  The  EPA  has
taken the broadest meeting of the term including any method of modifying the
chemical, biological, and/or physical character or composition of a  waste
(see Glossary).  Table 1-1 lists the types of treatment processes and their
EPA identification numbers which are used in the manifest system.  As seen
from the listing, treatment includes a wide array of specific  techniques;
but neither solidification nor stabilization is included.   Chemical  fixation
(T21) is listed under chemical treatment but is not specifically defined.
The chemical fixation category is the one under which all treatment
processes discussed in this document would fall except for  the encapsulation
techniques for which a separate category is listed under physical methods
(T39).  Table 1-2 lists some of the attributes of commonly-available,
hazardous waste treatment processes.  Note that different types of treatment
fulfill different functions on different forms and types of wastes.  Many
processes in Table 1-2 result only in volume reduction or waste separation
and thus still require solidification and stabilization of  the waste prior
to ultimate disposal.

     "Surface encapsulation" as used here is a technique of waste  treatment
involving isolation of the waste material by placing a jacket  or membrane of
impermeable, chemically inert material between the waste and the environment.
Ideally the jacket is bonded to the external surface of a solidified waste.
Encapsulation of small particles is sometimes called "microencapsulation,"
but this term is used by processors to describe a wide array of different
techniques and therefore has no specific meaning.

1.3  LEGISLATIVE BACKGROUND

     The Resource Conservation and Recovery Act  (RCRA) of  1976 (PL 94-580)
established a national hazardous waste regulatory program.  This law is  the
most comprehensive attempt  to date at guaranteeing the secured disposal  of
materials that could represent potential threats to human health and the
environment.  The Act includes provisions for developing criteria  to deter-
mine which wastes are hazardous, instituting a manifest system, and  estab-
lishing standards for siting, design, and operation of disposal facilities.
The Act encourages the States to conduct their own regulatory  programs,  but
it authorizes the U. S. Environmental Protection Agency  (EPA)  to administer

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       TABLE 1-1.  TREATMENT CODES FOR EPA HAZARDOUS WASTE MANIFESTS
     EPA
   Code #
Treatment
  EPA
Code #
Treatment
(a)  Thermal Treatment
     T06  Liquid injection incinerator
     T07  Rotary kiln incinerator
     T08  Fluidized bed incinerator
     T09  Multiple hearth incinerator
     T10  Infrared furnace incinerator
     Til  Molten salt destructor
     T12  Pyrolysis
     T13  Wet air oxidation
     T14  Calcination
     T15  Microwave discharge
     T16  Cement kiln
     T17  Lime kiln
     T18  Other (specify)
(b)  Chemical Treatment
     T19  Absorption mound
     T20  Absorption field
     T21  Chemical fixation
     T22  Chemical oxidation
     T23  Chemical precipitation
     T24  Chemical reduction
     T25  Chlorination              (d)
     T26  Chlorinolysis
     T27  Cyanide destruction
     T28  Degradation
     T29  Detoxification
     T30  Ion exchange
     T31  Neutralization
     T32  Ozonation
     T33  Photolysis
     T34  Other (specify)
(c)  Physical Treatment
     (1)  Separation of components
     T35  Centrifugation
     T36  Clarification
     T37  Coagulation
     T38  Decanting
     T39  Encapsulation
     T40  Filtration
     T41  Flocculation
     T42  Flotation
     T43  Foaming
     T44  Sedimentation
     T45  Thickening
     T46  Ultrafiltration
     T47  Other (specify)
                      (2)  Removal of Specific Components
                      T48  Absorption-molecular sieve
                      T49  Activated carbon
                      T50  Blending
                      T51  Catalysis
                      T52  Crystallization
                      T53  Dialysis
                      T54  Distillation
                      T55  Electrodialysis
                      T56  Electrolysis
                      T57  Evaporation
                      T58  High gradient magnetic
                           separation
                      T59  Leaching
                      T60  Liquid ion exchange
                      T61  Liquid-liquid extraction
                      T62  Reverse osmosis
                      T63  Solvent recovery
                      T64  Stripping
                      T65  Sand filter
                      T66  Other (specify)
                      Biological Treatment
                      T67  Activated sludge
                      T68  Aerobic lagoon
                      T69  Aerobic tank
                      T70  Anaerobic lagoon
                      T71  Composting
                      T72  Septic tank
                      T73  Spray irrigation
                      T74  Thickening filter
                      T75  Trickling filter
                      T76  Waste stabilization pond
                      T77  Other (specify)
                      T78-79  (Reserved)
NOTE:  Taken from reference 1-1.

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the program until suitable  State programs  are  established.   Should a State
choose not to develop a hazardous waste program or  not  to gain approval and
authorization for a program,  EPA must  administer the  program in its stead.

     Regulations have now been promulgated under the  RCRA that direct the
generation, handling, treatment, and safe  disposal  of hazardous and nonhaz-
ardous wastes.  Legal definitions of what  is hazardous  and  of  what consti-
tutes safe disposal have been developed  (1-1).

     The RCRA augments and  overlaps in some areas the authority delegated
to the agency in other legislation.  Previous  legislation had  addressed the
problem of hazardous waste  disposal indirectly  by regulating the effects of
waste disposal on surrounding air and  water quality.

     The Federal Water Pollution Control Act, as amended in 1972
(PL 92-500), and the Clean  Water Act of 1977  (PL 95-217) direct the estab-
lishment of an effluent permit plan for municipalities  and  industries,  but,
then do not specifically regulate discharges from solid or  hazardous waste
disposal activities.  However, in regional water quality planning (Sec-
tion 208 of the PL 92-500), any plan prepared must  include  a process to
control the dispersal of pollutants on land and in  subsurface  excavations to
protect the ground and surface waters.  Technically,  waste  disposal would be
controlled indirectly by enforcing a regional plan  to insure ground and
surface water quality.

     Under the Safe Drinking  Water Act of  1974  (PL  93-523),  the EPA Adminis-
trator is charged in Section  1442 with controlling  subsurface  emplacement of
waste.  The broad goal of this section is  to discover and control potential
threats to the quality of groundwater.  This Act is the basis  for regula-
tions on the subsurface injection of liquid waste and for surface impound-
ments.  An impoundment is defined as a natural  depression,  artificial
excavation, or diked enclosure used for storage, treatment,  or disposal of
wastes in the form of liquids, semisolids, or solids.   In its  broadest  inter-
pretation, the Safe Drinking  Water Act overlaps and reinforces the RCRA.

     The Toxic Substances Control Act  of 1976  (PL 94-469) established as
national policy that data should be developed on the  effects of the manufac-
ture, use, and disposal of  chemical substances  on health and the environment.
The EPA administrator is empowered to  prohibit  or otherwise regulate any
manner or method of disposal  of a toxic substance by  its manufacturer or by
any person who uses or disposes of a toxic chemical in  a commercial opera-
tion.  This provision includes all disposal of  toxic  substances on the  land
or in landfills or impoundments.  The  administrator is  authorized to take
action against persons disposing of a  toxic chemical  in any manner posing an
unreasonable risk to health and the environment.

     The Occupational Safety  and Health Act of  1970 specified  the maximum
permissible exposure limits for volatile,  hazardous chemicals  in the work
place.  Criteria established  under this legislation have been  adopted for
the disposal of hazardous industrial chemicals  that pose a  risk for airborne
contamination.  Under the RCRA and related legislation, the  EPA is now
responsible for all phases  of hazardous waste disposal.

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     Solidification/stabilization options are treated  indirectly  in  these
regulations.  For example, rules for landfilling waste  (1-1) state that
"liquids be modified and/or treated to a non-flowing consistency  prior to
landfilling or in situ."  No solidification requirement beyond  this  is for-
mally required.  Stabilization or chemical binding  to  prevent loss of toxic
constituents, is mentioned in a relation to the effect  to be obtained, not
as a specific system to be required.  The rules state  treatment renders  the
waste "...nonhazardous, safer to transport,..."  No specific treatment
systems are indicated  (1-1).  The performance in hazard reduction is the
important factor in selecting or requesting stabilization of toxic wastes.
This approach encourages inventiveness and allows for  flexibility in dis-
posal systems (1-2).

1.4  CHARACTERISTICS OF WASTES FOR WHICH STABILIZATION/SOLIDIFICATION ARE
     EFFECTIVE AND ECONOMICAL

     Not all wastes justify treatment.  The practical  and economic decision
concerning which wastes should or should not be submitted to expensive treat-
ment systems is based  upon an overall consideration of  the  amount, composi-
tion, physical properties, location, and disposal problems  associated with
the specific waste.  Also of importance is the proven  effectiveness  and  the
costs associated with  the commercially available treatment  systems which are
applicable to the specific wastes in question.  Wastes  which are  designated
as hazardous by the EPA and are produced in large amounts,  are  those most
commonly considered for solidification and/or stabilization.  Thus,  the
treatment of high volume hazardous waste forms the  bulk of  the  discussion  in
this manual.

     Some types of legally non-hazardous wastes also benefit from treatment
processes which would  render the waste more easily  handled  or less likely  to
lose undesirable constituents to the local groundwater.   For instance, flue
gas cleaning sludges,  although specifically exempted as nonhazardous solid
waste by EPA (1-1), have been the subject of a number  of  solidifications/
stabilization studies  since their run-off water and leachates are typically
high in calcium  (600-800 ppm) and sulfate (1200-1500 ppm) and represent  a
significant threat to  the local groundwater even if no  heavy metals  are
present  (1-3).  Other  wastes, whose disposal might  benefit  from treatment
are:  mining overburden returned to the mining site; fly  ash, bottom ash,
and slag wastes; flue  gas emission control wastes generated from  the burning
of fossil fuels; and oil, gas, or geothermal drilling  fluids.   These and
other wastes have been specifically listed as solid wastes  which  are non-
hazardous.

     Organic wastes are less amenable  to currently  available treatment  tech-
nology than are inorganic wastes.  This generalization holds for  a wide
variety of organic compounds with a diverse array of properties which occur
in common wastes streams.  Wastes with greater than 10 to 20 percent organic
constituents are not generally recommended for treatment  by current,
commercial fixation techniques as the  organics interfere  with the physical
and chemical processes which are important in binding  the waste materials
together  (1-4).  Some  processors who handle large volumes of inorganic

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wastes will accept relatively small volumes of  selected  organic  wastes which
are mixed to a low concentration  in the  inorganic waste  treatment  stream.

     Organic wastes lend themselves to destructive  treatment  by  processes
such as incineration, UV-ozone or biological  systems.  Such treatments prop-
erly employed produce innocous products  (mainly CO   and  water) which after
scrubbing can be vented directly  to the  atmosphere.   Since the hazardous
organic-waste components are destroyed,  all of  the  problems associated with
ultimate disposal such as leachate or vapor losses,  land use  and reclamation,
and long-term manifest or record  keeping are  eliminated. Even for wastes
containing only moderate to small amounts of  organics, the organic fraction
is often best first separated by  solvent extraction or distillation so that
it can be disposed of separately.  The volume of ash and/or flue gas
scrubber sludge left after destructive treatment will vary widely  with the
type of organic material being treated,  but will almost  always be  a small
fraction of the original organic  waste.

     In summary, the wastes most  effectively  stabilized/solidified consist
mainly of inorganic materials in  aqueous solution or suspension  which con-
tain appreciable amounts of toxic heavy  metals  and/or inorganic  salts.  It
is also towards these waste types that most stabilization/solidification
techniques are directed.

1.5  DELISTING TREATED HAZARDOUS  WASTE PRODUCTS

     Hazardous wastes which have  undergone any  treatment processes are still
considered hazardous unless an exemption has  been petitioned  for,  and
granted, by the EPA for the specific waste in question.   The  process of
removing a particular waste from  the hazardous  waste category (called "de-
listing") is considered by EPA as a modification of the  original listing
determination and is, therefore,  treated as an  amendment to the  lists of
hazardous waste.

     To be successful, the petitioner must demonstrate that the  waste pro-
duced by a particular process or  treatment facility does not  meet  any of the
criteria under which the waste which was listed as  a hazardous waste.  If
the treated waste is a mixture of solid  waste,  and  if one or  more  of the
wastes is listed as hazardous  (or is derived  from one or more hazardous
wastes), the demonstration of non-hazardous character may be  made  with
respect to each constituent listed as a  hazardous waste, or the  waste mix-
ture as a whole.  If the waste is listed as hazardous because it exhibits
one of the characteristics of hazardous  wastes  (ignitability, corrosivity,
reactivity, or extractant procedure toxicity),  then the  petitioner must show
that demonstration samples of the treated waste products do not  exhibit that
characteristic.  The applicable testing  procedures  must  be employed.

     If any of the hazardous wastes present in  the  treated wastes  are listed
because they are made up of, or contained, toxic components then the peti-
tioner must demonstrate that the  treated waste  no longer contains  the toxic
component, or if still present, that the toxic  component is not  capable of
posing a substantial present or potential threat to human health or the

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environment.  If the waste was listed because  it  contains  an  "acute  hazardous
waste," in addition to demonstrating lack of toxicity,  the waste  must  be
shown to be non-fatal to humans in low doses or,  if  human  data is not  avail-
able, to not be fatal to other mammals at doses higher  than those prescribed.

     Thus delisting of solidified/stabilized waste is possible upon  the
demonstration to EPA's satisfaction that the component  or  characteristic for
which the waste was listed is no longer present or applicable to  the treated
product.  This determination of the non-hazardous character of the waste
product makes possible the much cheaper and less  rigorous  disposal of  the
wastes in any solid waste landfill.  The use of the  waste  in  any  productive
way  (such as foundation, fill, or construction materials)  must be preceded
by the delisting of the product as a hazardous waste.   It  is  unlikely  that a
whole waste-stream can be permanently delisted, or that a  particular waste
fixation process can be certified as producing a  non-hazardous product irre-
gardless of changes in the process parameters  or  in  the wastes being treated.

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                                  REFERENCES
1-1.   U. S.  Environmental Protection Agency.  Hazardous Wastes Management
      System.   Federal Register, 45(98):33063-33285, May 19,  1980.

1-2.   Wright,  A. P. and H. A. Coates.  Legislative Initiatives for
      Stabilization/Solidification of Hazardous Wastes.  In:  Toxic and
      Hazardous Waste Disposal, Vol. 2, R. B. Pojasek, ed.  Ann Arbor
      Science Publ. Inc., Ann Arbor, MI,  1978.  pp. 1-15.

1-3.   Duvel, W. A.  and others.  State-of-the-Art of FGD Sludge Fixation.
      EPRI FP-671.   Electric Power Research Institute, Palo Alto, California,
      1978.   268 pp.

1-4.   Malone,  P. G. and L. W. Jones.  Survey of Solidification/Stabilization
      Technology for Hazardous Industrial Wastes.  EPA 600/2-79-056.  U. S.
      Environmental Protection Agency, Municipal Environmental Research
      Laboratory, Cincinnati, Ohio, 1979.  41 pp.

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                                   SECTION 2

                 WASTE STABILIZATION/SOLIDIFICATION TECHNOLOGY


2.1  CURRENT STABILIZATION/SOLIDIFICATION TECHNOLOGY

     Several stabilization/solidification methods now available or under de-
velopment have as their goal the safe ultimate disposal of hazardous waste
either via a productive way or by landfilling.  Ultimate disposal implies
the final disposition of persistent, nondegradable, cumulative, and/or harm-
ful waste.  The four primary goals of treating hazardous waste for ultimate
disposal are:  (a) to improve the handling and physical characteristics of
the waste, (b) to decrease the surface area across which transfer or loss of
contained pollutants can occur, (c) to limit  the solubility of any pollu-
tants contained in the waste, and (d) to detoxify contained pollutants.
These goals can be met in a variety of ways,  but not all techniques attempt
to meet all the goals.  Thus individual treatment techniques may solve one
particular set of problems but be completely  unsatisfactory for others.
Process selection becomes weighing advantages and disadvantages for the
particular situation.

     The following major categories of industrial waste fixation systems are
discussed in this section:

     a.  Cement-based processes

     b.  Pozzolanic processes (not including  cement)

     c.  Thermoplastic techniques (including  bitumen, paraffin, and poly-
         ethylene incorporation)

     d.  Organic polymer techniques (including urea-formaldehyde, unsaturated
         polyester)

     e.  Surface encapsulation techniques  (jacketing)

     f.  Self-cementing techniques (for high  calcium sulfate sludges)

     g.  Classification and production of synthetic minerals or ceramics

Examples of treated waste materials are shown in Figure 2-1.  Since these
waste treatment systems vary widely in their  applicability, cost, and  pre-
treatment requirements, many are limited as to the types of waste that can
be economically processed.  Selection of any  particular technique for  waste


                                      10

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treatment must include careful consideration of the containment  required,
the cost of processing, the increase in bulk of material, and  the  changes  in
the handling characteristics.  The design and  location of any  placement  area
or landfill that eventually receives the treated waste is also a major con-
sideration in deciding on the degree of containment and the physical prop-
erties that will be required.

2.2  CEMENT-BASED PROCESSES

     Common (portland) cement is produced by firing a charge of  limestone
and clay or other silicate mixtures at high temperatures.  The resulting
clinker is ground to a fine powder to produce  a cement that consists of
about 50% tricalcium and 25% dicalcium silicates (also present are about 10%
tricalcium aluminate and 10% calcium aluminoferrite).  The cementation pro-
cess is brought about by the addition of water to the anhydrous  cement
powder.  This first produces a colloidal calcium-silicate-hydrate  gel of in-
definite composition and structure.  Hardening of the cement is  a  lengthy
process brought about by the interlacing of thin, densely-packed,  silicate
fibrils growing from the individual cement particles.  This fibrillar matrix
incorporates the added aggregates and/or waste into a monolithic,  rock-like
mass.

     Five types of Portland cements are generally recognized,  based on varia-
tions in their chemical composition and physical properties  (3-!).

     a.  Type I is the typical cement used in  the building trade,  and consti-
         tutes over 90% of the cement manufactured in the United States.

     b.  Type II is designed to be used in the presence of moderate sulfate
         concentrations (150 to 1500 mg/kg) or where moderate  heat of hydra-
         tion is required.

     c.  Type III has an high early strength and is used where a rapid set
         is required.

     d.  Type IV develops a low heat of hydration and is usually prescribed
         for large-mass concrete work but has  long set time.

     e.  Type V is a special low-alumina, sulfate-resistant  cement used  with
         high sulfate concentrations (>1500 mg/kg).

The types that have been used for waste solidification are Type  I  and,  to a
smaller extent, Types II and V.

     Most hazardous waste slurried in water can be mixed directly  with
cement, and the suspended solids will be incorporated into the rigid ma-
trices of the hardened concrete.  This process is especially  effective  for
waste with high levels of toxic metals, since  at the pH of the cement mix-
ture, most multivalent cations are converted into insoluble  hydroxides  or
carbonates.  Metal ions may also be incorporated into the crystal  structure
of the cement minerals that form.  Materials in the waste such as  sulfides,
                                       12

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asbestos, latex, and solid plastic wastes may  actually  increase the strength
and stability of the waste concrete.

Interfering Compounds—
     The presence of certain inorganic  compounds  in  the hazardous  waste and
the mixing water can be deleterious to  the setting and  curing  of the waste-
containing concrete (2-1).  Also, impurities such as organic materials, silt,
clay, or lignite may delay the setting  and curing of common portland cement
for as long as several days. fiAll insoluble materials passing  through a
No. 200 mesh sieve ( 74 x  10   m particle size) are  undesirable, as they may
be present as dust or may  coat the larger particles  and weaken the bond
between the particles and  the cement.   Soluble salts of manganese,  tin, zinc,
copper, and lead may cause large variations in setting  time and significant
reduction in physical strength.  Salts  of zinc, copper,  and lead are the
most detrimental.  Other compounds that are especially  active  as setting
retarders in portland cement include sodium salts of arsenate,  borate,  phos-
phate, iodate, and sulfide—ev^n at concentrations as low as a few tenths of
a percent of the weight of the cement used.  Products containing large
amounts of sulfate (such as flue gas cleaning  sludges)  not only retard  the
setting of concrete, but by reacting to form calcium sulfoaluminate hydrate,
they cause swelling and spalling in the solidified waste-containing concrete.
To prevent this reaction, a special low-alumina  (Type V)  cement was devel-
oped for use in circumstances where high sulfate  is  encountered.

Additives—
     A number of additives have been developed for use  with cement to im-
prove the physical characteristics and  decrease the  leaching losses from the
resulting solidified sludge.  Many of the additives  used in waste  treatment
are proprietary and cannot be discussed here.  Experimental work on the
treatment of radioactive waste has shown some  improvement in cement-based
fixation and retention of nuclear waste with the  addition of clay  or vermi-
culite as absorbents (2-2).  Soluble silicate  has reportedly been  used  to
bind contaminants in cement solidification processes, but this  additive
causes an increase in volume to occur during the  setting of the cement-waste
mixture.  A recently proposed adaptation of this  technique involves dissolv-
ing the metal-rich waste with fine-grained silica at low pH and then poly-
merizing the mixture by raising the pH  to 7.   The resulting contaminated gel
is mixed with cement and hardens within 3 days.

     Recent testing by Brookhaven National Laboratory indicates that a  mix-
ture of sodium silicate and Type II portland cement  produces a  rapid set
with no retardation from metallic ions  (2-2).  The sodium silicate appears
to precipitate most interfering ions in a gelatinous mass and  so to remove
their interferences and to speed setting.  Of  the wastes  tested, only boric
acid waste inhibited the set of the cement mixture.   The development of a
gel is important in the setting of the  cement-waste-silicate mixtures.   Ex-
cessive mixing after the gel forms seems to cause slower setting and lessen
final strength of the product.

Polymer Impregnation—
     The Brookhaven National Laboratory also developed  a polymer impregnation


                                      13

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process that can be used to decrease the permeability  of  concrete-waste
mixtures (2-3).  The pores of the waste-concrete are filled by  soaking  in
styrene monomer.  The soaked material is then heated to bring about  polymer-
ization.  This process results in a significant increase  in the strength  and
durability of the concrete-waste mixture.

Coatings—
     Surface coating of concrete-waste  composites has  been examined  exten-
sively.  The major problems encountered have been poor adhesion of the  coat-
ing onto the waste or lack of strength  in  the concrete material containing
the waste.  Surface coating materials that have been investigated  include
asphalt, asphalt emulsion, and vinyl.   However, no  surface coating system
for cement-solidified material is currently being advertised.

Advantages and Disavantages—
     Advantages of the cement treatment systems are:

     a.  The amount of cement used can  be  varied  to produce high bearing
         capacities (making the waste concrete good subgrade and subfounda-
         tion materials) and low permeability in  the product.

     b.  Raw materials are plentiful and inexpensive.

     c.  The technology and management  of  cement mixing and handling is well
         known, the equipment is commonplace, and specialized labor  is  not
         required.

     d.  Extensive drying or dewatering of waste  is not required because
         cement mixtures require water, and the amount of cement added  can
         be adapted through wide ranges of water  contents.

     e.  The system is tolerant of most chemical variations.  The  natural
         alkalinity of the cement used  can neutralize  acids.  Cement is not
         affected by strong oxidizers such as nitrates or chlorates.  Pre-
         treatment is required only for materials that retard or interfere
         with the setting action of cement.

     f.  Leaching characteristics can be improved where necessary  by coating
         the resulting product with a sealant.

     Disadvantages of cement-based systems are:

     a.  Relatively large amounts of cement are required  for most  treatment
         processes (but this may partly be offset by  the  low  cost  of mate-
         rial) .  The weight and volume  of  the final product is  typically
         about double those of other solidification processes.

     b.  Uncoated cement-based products may require a  well-designed  landfill
         for burial.  Experience in radioactive waste  disposal  indicates
         that some wastes are leached from the solidified concrete,  espe-
         cially by mildly acidic leaching  solutions.


                                      14

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     c.  Extensive pretreatment, more expensive  cement  types  or  additives
         may be necessary for waste containing large amounts  of  impurities
         such as borates and sulfates that affect  the setting or curing of
         the waste-concrete mixture.

     d.  The alkalinity of cement drives off ammonium ion as  ammonia  gas.

     e.  Cement is an energy-intensive material.

2.3  POZZOLANIC PROCESSES (NOT  CONTAINING CEMENT)

     Waste fixation techniques  based on lime products usually depend  on the
reaction of lime with a fine-grained siliceous (pozzolanic) material  and
water to produce a concrete-like solid  (sometimes  referred  to as a  pozzolanic
concrete).  The most common pozzolanic materials used in waste treatment are
fly ash, ground blast-furnace salg, and cement-kiln dust.   All of these mate-
rials are themselves waste products with little  or no commercial value  at
this time.  The use of these waste products to consolidate  another  waste is
often advantageous to the processor, who can treat two  waste  products at the
same time.  For example, the production of a pozzolanic reaction with power
plant fly ash permits the flue  gas cleaning sludge to be combined with  the
normal fly ash output and lime  (along with other additives) to product  an
easily-handled solid.  Many, if not all, of the  comments associated with the
cement systems apply to the pozzolanic systems including advantages and
disadvantages.

     Advantages of lime-based treatment techniques that produce  pozzolanic
cement are several:

     a.  Product is generally a solid with improved handling  and permeabil-
         ity characteristics.

     b.  The materials are often very low in cost  and widely  available.

     c.  Little specialized equipment is required  for processing, as  lime is
         a common additive in other waste streams.

     d.  The chemistry of lime-pozzolanic reactions are relatively
         well-known.  Sulfate does not cause spalling or cracking.

     e.  Extensive dewatering is not necessary because  water  is  required in
         the setting reaction.

     The lime-based systems have many of the same  potential disadvantages as
cement-based techniques:

     a.  Lime and other additives add to the weight and bulk  to  be  trans-
         ported and/or landfilled.

     b.  Uncoated lime-treated  materials may require specially designed
         landfills to guarantee that the material  does  not  lose  potential
         pollutants by leaching.

                                      15

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     Certain treatment systems fall in the category of cement-pozzolanic
processes and have been in use for some time outside the U.  S.   In  this case
both cement and lime-siliceous materials are used  in combination to give  the
best and most economical containment for the specific waste  being treated.
In general, the bulk of the comments under both classifications  above  hold
for techniques using a combination of treatment materials.

2.4    THERMOPLASTIC TECHNIQUES (INCLUDING
       BITUMEN, PARAFFIN AND POLYETHYLENE)

     The use of thermoplastic solidification systems in radioactive waste
disposal has led to the development of waste containment systems that  can be
adapted to industrial waste.  In processing radioactive waste  with  bitumen
or other thermoplastic material, the waste is dried, heated, and dispersed
through a heated plastic matrix.  The mixture is then cooled to  solidify  the
mass, and it is usually buried in a secondary containment  system such  as  a
steel drum.  Variations of this treatment system can use thermoplastic or-
ganic materials such as paraffin or polyethylene.

     The process requires some specialized equipment to heat and mix the
waste and plastic matrices, but equipment for mixing and extruding  waste
plastic is available.  The ratio of matrix to waste is generally quite
high—a 1:1 to 1:2 ratio of incorporation material to waste  (on  a dry-weight
basis).  The plastic in the dry waste must be mixed at temperatures ranging
from 130° to 230°C, depending on the melting characteristics of  the material
and type of equipment used.

     A variation of this process uses an emulsified bitumen  product that  is
miscible with a wet sludge.  In this process, the  mixing can be  done at any
convenient temperature below the boiling point of  the mixture.   The overall
mass must still be heated and dried before it is suitable  for  disposal.
Ratios of emulsions to waste of 1:1 to 1:1.5 are necessary for adequate  in-
corporation (2-2).

     In many cases, the types of waste rule out the use of any organic-based
treatment systems.  Organic chemicals that are solvents for  the  matrix obvi-
ously cannot be used directly in the treatment system.  Strongly oxidizing
salts such as nitrates, chlorates, or perchlorates will react  with  the
organic matrix materials and cause slow deterioration.  At the elevated  tem-
peratures necessary for processing, the matrix-oxidizer mixtures are ex-
tremely flammable.

     Leach or extraction testing undertaken on anhydrous salts embedded in
bitumen as a matrix indicates that rehydration of  the embedded compound  can
occur when the sample is soaked in water and can cause the asphalt  or  bitumen
to swell and split apart, greatly increasing the surface area  and rate of
waste loss (2-2).  Some salts (such as sodium sulfate) will  naturally  dehy-
drate at the temperatures required to make the bitumen plastic;  so  these
easily dehydrated compounds must be avoided in thermoplastic stabilization.

     The major advantages of the thermoplastic-based disposal  systems  are:
                                       16

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     a.  The rate of loss to contacting  fluids are  significantly  lower than
         those observed with cement-based and pozzolon  systems.

     b.  By disposing of the waste in a  dry condition,  the  overall  volume of
         the waste is greatly reduced.

     c.  Most thermoplastic matrix materials are  resistant  to  attack by
         aqueous solutions, and microbial degradation is minimal.

     d.  Most matrices adhere well to incorporated  materials.

     e.  Materials embedded in a thermoplastic matrix can be reclaimed if
         needed.

     The principal disadvantages of the  thermoplastic-based disposal systems
are:

     a.  Expensive, complicated equipment requiring highly  specialized labor
         is necessary for processing.

     b.  The plasticity of the matrix-waste mixtures may require  that con-
         tainers be provided for transportation and disposal of the mate-
         rials, which greatly increases  the cost.

     c.  The waste materials to be incorporated must be dried, which re-
         quires large amounts of energy.  Incorporating wet wastes  greatly
         increases losses through leaching.

     d.  These systems cannot be used with materials that decompose at high
         temperatures, especially citrates and certain  types of plastics.

     e.  There is a risk of fire in working with  organic materials  such as
         bitumen at elevated temperatures.

     f.  During heating, some mixes can  release objectionable  oils  and odors
         causing secondary air pollution.

     g.  The incorporation of tetraborates of iron  and aluminum salts in
         bitumen matrices causes premature hardening, and can  clog  and
         damage the mixing equipment.

     h.  Strong oxidizers usually cannot be incorporated into  organic mate-
         rials without the occurrence of oxidizing  reactions.  High concen-
         trations of strong oxidizers at elevated processing temperatures
         can cause fires.

     i.  Dehydrated salts incorporated in the thermoplastic matrix  will
         slowly rehydrate if the mixture is soaked  in water.   The rehydrated
         salt will expand the mixture causing the waste block  to  fragment
         and increasing its surface area greatly.
                                      17

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2.5  ORGANIC POLYMER PROCESSES

     Organic polymer techniques were developed as a  response  to  the  require-
ment for solidification of waste for transportation.  The most thoroughly
tested organic polymer solidification technique  is the urea-formaldehyde  (UF)
system.  The polymer is generally formed in a batch  process where  the  wet  or
dry wastes are blended with a prepolymer in a waste  receptacle  (steel  drum)
or in a specially-designed mixer.  When these two components  are thoroughly
mixed, a catalyst is added, and mixing is continued  until the catalyst is
thoroughly dispersed.  Mixing is terminated before the polymer has formed
and the resin-waste mixture is transferred to a  waste container  if necessary.
The polymerized material does not chemically combine with the waste—it
forms a spongy mass that traps the solid particles.  Any liquid  associated
with the waste will remain after polymerization.  The polymer mass must
often be dried before disposal.

     Several organic polymer systems are available that are not  based  on UF
resins.  Dow Industrial Division is developing a vinyl ester-styrene system
(Binder 101) for use with radioactive waste  (2-4).   Testing of  this  material
is currently underway in the Nuclear Regulatory  Commission Research  Programs.

     The Polymeric Material Section at Washington State University has de-
veloped a polyester resin system that is being used  in solidification  of
waste.  This system is currently in a pilot-plant stage in the  processing  of
hazardous wastes (2-5, 2-6, 2-7).

     The major advantages of the organic polymer systems  (especially the
UF-resin system) are:

     a.  Less treatment reagent is required  for  solidifying the  waste  than
         in other systems.  The waste-to-reagent ratio is usually  about 30%
         greater for a UF organic polymer system than with cement.

     b.  The waste material treated is usually dewatered, but it is  not
         necessarily dried as in thermoplastic processes.   (The  finished,
         solidified polymer, however, must be dried  before ultimate
         disposal.)

     c.  The organic resin used is consistently  less dense  (specific gravity
         is approximately 1.3) than cement.  The low density  reduces the
         transportation cost related to the  reagents and  to the  treated
         products.

     d.  The solidified resin is nonflammable, and high  temperatures are
         not required in forming the resin.

     The major disadvantages of the organic  resin  techniques, especially
the UF resin systems are:

     a.  No chemical reactions occur in the  solidification process that
         chemically binds the potential pollutants.  The  particles of  waste
                                       18

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         material are trapped in an organic resin matrix, and breakdown  or
         leaching of the matrix will release many of the waste materials.

     b.  Catalysts used in the UF systems are strongly acidic, and  the
         waste-UF mixture must be maintained at pH  1.5 ± 0.5 for  solidifica-
         tion to occur in a rapid manner.  The low  pH can put many  waste
         materials into solution.  If the pH is not lowered to 1.5,  the
         polymerization is slow; solids will thus settle out, and the waste
         material will not be trapped effectively.

     c.  Uncombined or weep water is often associated with polymerized
         waste.  This must be allowed to evaporate  to produce a fully-cured
         polymer.  This weep water may be strongly  acidic and may contain
         high levels of pollutants.  Waste-UF mixtures shrink as  they age
         and will produce weep water during aging.

     d.  Some catalysts used in polymerization are highly corrosive  and  re-
         quire special mixing equipment and container liners.

     e.  The reaction producing the resin may release fumes that  can be
         harmful or disagreeable even in low concentrations.

     f.  Some cured resins, especially UF-based systems, are biodegradable
         and have a high loss of chemical oxygen demand.

     g.  Secondary containment in steel drums is a  common practice  in the
         use of organic resins, which increases the cost of processing and
         transportation.

2.6  SURFACE ENCAPSULATION TECHNIQUES (JACKETING)

     Many waste treatment systems depend on binding particles of  waste mate-
rial together.  To the extent to which the binder coats the waste particles,
the wastes are encapsulated.  However, the systems  addressed under  surface
encapsulation are those in which a waste that has been pressed or bonded
together is enclosed in a coating or jacket of inert material.  A number of
systems for coating solidified industrial wastes have been examined by TRW
Corporation (2-3).  In most cases, coated materials have suffered from lack
of adhesion between coatings and bound wastes, and  lack of long-term integ-
rity in the coating materials.  After investigating many alternative binding
and coating systems, TRW Corporation produced detailed plans for  what it
considered to be the optimum encapsulation system.  The TRW—developed system
has been tested and published data on the processes are available (2-8).

     The TRW surface encapsulation system requires  that the waste material
be thoroughly dried.  The dried wastes are stirred  into an acetone  solution
of modified 1,2-polybutadiene for 5 min.  The mixture is allowed  to  set  for
2 hr.  The optimum amount of binder is 3% to 4% of  the fixed material on a
dry-weight basis.  The coated material is placed in a mold, subjected to
slight mechanical pressure, and heated to between 120° and 200°C  (250° and
400°F) to produce fusion.  The agglomerated material is a hard, tough, solid


                                      19

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block.  A polyethylene jacket 3.5 mm  (1/4 in.) thick is  fused  over  the  solid
block and adheres to the polybutadiene binder.  In a 360-  to 450-kg  (800-  to
1000-lb) block, the polyethylene would amount to 4% of the fused waste  on  a
weight basis (see Fig. 2-2).

     The major advantages of an encapsulation process are:

     a.  The waste material never comes into contact with  water, therefore,
         soluble materials such as sodium chloride can be  successfully  sur-
         face encapsulated.

     b.  The impervious jacket eliminates all leaching into contacting  waters
         as long as the jacket remains intact.

     The major disadvantages of encapsulation are:

     a.  The resins required for encapsulating are expensive.

     b.  The process requires large expenditures of energy in  drying, fusing
         the binder, and forming the  jacket.

     c.  Polyethylene is combustible, with a flash point of 350°C,  making
         fires a potential hazard.

     d.  The system requires extensive capital investment  and  equipment.

     e.  Skilled labor is required to operate the molding  and  fusing
         equipment.

2.7  SELF-CEMENTING PROCESSES

     Some industrial wastes such as flue-gas cleaning or desulfurization
sludges contain large amounts of calcium sulfate and calcium sulfite.   A
technology has been developed to treat these types of wastes so  that they
become self-cementing (2-9).  Usually a small portion  (8%  to 10% by weight)
of the dewatered waste sulfate/sulfite sludge is calcined  under  carefully
controlled conditions to produce a partially dehydrated  cementitious calcium
sulfate or sulfite.  This calcined waste is then reintroduced  into  the  bulk
of the waste sludge along with other  proprietary additives.  Fly ash is
often added to adjust the moisture content.  The finished  product  is a  hard,
plaster-like material with good handling characteristics and low permeabil-
ity.  The major advantages of self-cementing systems are:

     a.  The material produced is stable, nonflammable,  and
         nonbiodegradable.

     b.  There are reports of effective heavy metal retention, which is
         perhaps related to chemical  bonding of potential  pollutants.

     c.  No major additives have to be manufactured and  shipped  to  the
         processing site.


                                      20

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21

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     d.  The process is reported to produce faster setting time and more
         rapid curing than comparable lime-based systems.

     e.  These systems do not require completely dry waste.  The hydration
         reaction uses up water.

     The major disadvantages of self-cementing systems are:

     a.  Self-cemented sludges have much the same leaching characteristics
         as cement and lime-based systems.

     b.  Only high calcium sulfate or sulfite sludges can be used.

     c.  Additional energy is required to produce the calcined cementitious
         material.

     d.  The process requires skilled labor and expensive machinery in  cal-
         cining wastes and mixing the calcined wastes back to the bulk  of
         the waste with proprietary additives.

2.8  CLASSIFICATION AND PRODUCTION OF SYNTHETIC MINERALS OR CERAMICS

     Where material is extremely dangerous or radioactive, it is possible
to combine the waste with silica and either fuse the mixture in glass or to
form a synthetic silicate mineral (2-10, 2-11).  Glasses or crystalline
silicates are only very slowly leached by naturally occurring waters, so
these waste products are generally considered to be safe materials for  dis-
posal without secondary containment.  No work using glassification of
industrial wastes are now going on.

     The major advantages of glassification or mineral synthesis are:

     a.  The process is assumed to produce a high degree of containment of
         wastes.

     b.  The additives used can be relatively inexpensive  (syenite and
         lime).

     The major disadvantages of these processes are:

     a.  Some constituents  (especially metals) may be vaporized and lost
         before  they can bind with the molten silica if  high-temperature
         processes are used.

     b.  The process is energy-intensive.  The waste-silicate charge  must
         be heated  (often up to 1350°C) for melting and  fusion.

     c.  Socialized equipment  and trained personnel are required  for this
         type of operation.
                                       22

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2.9  SUMMARY

     A wide variety of possible techniques exist  for waste  treatment.
Obviously, no system is applicable to every waste  in all  situations.   The
amount and character of the material to be stabilized,  the  economics  in-
volved and the properties of the disposal site  (see Section 7)  are  all
important factors in deciding which treatment procedures  are best for  any
given situation.  By careful evaluation of economics, the hazardous nature
of the material, and the containment provided by  geologic and hydrologic
situations at nerby landfills, it should be possible to establish a minimum
cost for responsible disposal of a particular waste.  A list of companies
marketing stabilization/solidification technology  in the  United States is
given in Appendix B.

     The cost for waste treatment processes depends on  the  volume of  the
waste to be fixed.  Therefore, it may become cost-advantageous  to concentrate
hazardous wastes into a minimum volume to reduce handling and additive re-
quirements.  When hazardous wastes are concentrated, the  precautions  involved
in handling and transportation are necessarily  increased, so onsite stabili-
zation or solidification is desirable.  In fact,  stabilization/solidification
may become a unit operation to complete a waste treatment system.   The waste
treatment operations could be tailored to produce  the hazardous residue in  a
minimum volume with a pH and chemical composition  compatible with the  treat-
ment system that is required to insure safe containment under specific land-
fill conditions.
                                      23

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                                  REFERENCES
2-1.  Popovics, Sandor.  Concrete-Making Materials.  McGraw-Hill, New York,
      N.  Y., 1979.  370 pp.

2-2.  Columbo, P. and R. M. Neilson, Jr.  Properties of Radioactive Wastes
      and Waste Containers.  Progress Report No. 7, BNL-NUREG 50837, Brook-
      haven National Laboratory, Upton, N. Y., 1978.  61 pp.

2-3.  Burk, M. R., R. Denham, and H. Lubowitz.  Recommended Methods of Re-
      duction, Neutralization, Recovery or Disposal of Hazardous Wastes.
      Vol. 1Y TRW Systems Group, Inc., Redondo Beach, Calif. June 1974.
      89 pp.

2-4.  Columbo, P. and R. M. Neilson, Jr.  Properties of Radioactive Wastes
      and Waste Containers.  Progress Report No. 5, BNL-NUREG 50763, Brook-
      haven National Laboratory, Upton, N. Y., 1977.  32 pp.

2-5.  Mahalingam, R., M. Juloori, R. V. Subramanian, and Wen-Pao Wu.  Pilot
      Plant Studies on the Polyester Encapsulation Process  for Hazardous
      Wastes.  In:  Proceedings of the National Conference  on Treatment and
      Disposal of Industrial Wastewaters and Residues, Houston, Texas,  1977,
      107 pp.

2-6.  Subramanian, R. V., Wen-Pao Wu, R. Mahalingam and M.  Juloori.  Poly-
      ester Encapsulation of Hazardous Industrial Wastes.   In:  Proceedings
      of the National Conference on Treatment and Disposal  of Industrial
      Wastewaters and Residues, Houston, Texas, 1977.  107  pp.

2-7.  Subramanian, R. V. and R. Mahalingam.  Immobilization of Hazardous
      Residuals by Polyester Encapsulation.  pp 247-269 In:  R. B.  Pojasek,
      ed.  Toxic and Hazardous Waste Disposal, Vol. 1.  Ann Arbor Science
      Publishers, Inc., Ann Arbor, Mich., 1979.  407 pp.

2-8.  Lubowitz, H. R., R. L. Denham and G. A. Zakrzewski.   Development  of
      a Polymetric Cementing and Encapsulating Process for  Managing Haz-
      ardous Wastes.  EPA-600/2-77-045, U. S. Environmental Protection
      Agency, Cincinnati, Ohio,  1977.  167 pp.

2-9.  Valiga, R.  The SFT Terra-Crete Process,  pp. 155-166, In:  R. B.
      Pojasek, ed.  Toxic and Hazardous Waste Disposal, Vol. 1.  Ann
      Arbor, Mich.,  1979.  407 pp.
                                       24

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2-10.  Gilmore, W. R. (ed).  Radioactive Waste Disposal, Low  and High
       Level.  Noyes Data Corp., Park Ridge, N. J.,  1977.   363 pp.

2-11.  Kerr, R. A.  Nuclear Waste Disposal:  Alternatives  to  Solidification
       in Glass Proposed.  Science 204:289-291, 1979.
                                      25

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                                   SECTION  3

                   PROPERTIES OF STABILIZED/SOLIDIFIED WASTES

     Selection of the best treatment system requires detailed  knowledge  of
the constituents and characteristics of the waste to be  treated,  the  amount
of waste to be handled, and the location and environment  of  the waste dis-
posal site.  This section deals with the characteristics  that  an  ideal
treatment system and its product would be expected  to have and the  major
considerations that are involved in the selection of the  best  treatment  sys-
tem for a specific waste stream.

3.1  CHARACTERIZING OF WASTES TO BE TREATED

     The first step in selection of the best system involves a detailed
knowledge of the wastes to be treated.  A complete  inventory of all constit-
uents in the waste streams should be made.  The  source and amount of  each
waste type (including the process or operation that produces it,  how  it  is
transported, stored, and treated, and its production rate and  production
schedule) should be determined.  This information is necessary for  selection
processes and will be required for disposal planning.

     A complete knowledge of all components of all  waste  streams  at a par-
ticular site is of great importance.  Much  information can be  gained  from
the knowledge of the process or operation by which  the waste is produced.
This detailed information should include types of materials  and concentra-
tions, organic constituents, solvents, etc.  Where  organics are present,  it
is essential to know details about chemical stability, flash points,  and
heating value.  The inorganic components and their  relative  concentrations
must be determined.  Toxic heavy metals, even in small concentrations, are a
major concern.  The pH, buffering capacity, and  water content  of  the  waste
are of critical importance in many solid waste treatment  systems.

3.2  REQUIREMENTS FOR IDEAL WASTE STABILIZATION/SOLIDIFICATION

     The ideal fixation process renders the noxious constituents  chemically
nonreactive and/or immobile so that no secondary containment is necessary
for safe disposal.  For example, incorporation into a stable crystal  lattice
effectively isolates noxious materials from any  environmental  interactions,
and maintaining the pH in the range of 9 to 11 immobilizes most multivalent
cations as insoluble hydroxides and other compounds.  Sludges  with  high
concentrations of particular cations can be treated with additives  chosen
specifically to immobilize these contaminants.   Anions,  although  typically
much less toxic, are much more difficult to bind into an unleachable  product,
Chlorides and sulfates, the most common anionic  sludge components,  produce
                                       26

-------
only a few insoluble salts.  To contain anions  such as  these  the waste  must
be physically isolated from any leaching medium by secondary  containment  or
special landfill covers.

     To be completely effective, the waste  treatment must  produce  a  final
mixture whose physical properties are such  that its disposal  does  not perma-
nently render the land unsuitable for alternative uses  such as  building
sites or agriculture.  However, the production  of treated  wastes with "soil-
like" character that might be suitable for  agricultural use seems  unlikely
in cases where the major contaminants are toxic metals,  certain organics,
and/or high levels of salt.  The long-term  action of organic  acids normally
produced by the biological activity in agricultural soils  would be expected
to mobilize even the most tightly bound contaminant eventually. Such mobi-
lized constituents would then be taken into the food chain or washed into
the groundwater.  The most secure final form of treated waste appears to  be
monolithic mass that has good dimensional stability, freeze-thaw resistance,
low permeability, a high bearing capacity,  and  resistance  to  attack  by
biological agents.  An end product such as  this could be used as a founda-
tion for buildings or roads, or simply buried and covered  over  in  a  landfill.

     The ideal treatment process does not require extensive heat treatment
or large amounts of energy-intensive reactants.  Also,  the waste material
should be reclaimable by some reasonable technique, since  some  of  the sludge
contaminants  (e.g., manganese and chromium)  are predicted  to  be in critical
supply in the future.

     These are rather stringent requirements for any waste treatment pro-
cess.  A great deal of study by private industry and government is going
into the development of better treatment procedures.  However,  with  current
technology and with complete knowledge of the waste to  be  treated  and the
treatment processes available, the production of finished  products that will
approximate the ideal stabilized material is possible.

3.3  COMPATIBILITY OF WASTES AND TREATMENT  ADDITIVES

     As in any hazardous waste handling operation, care must  be taken
during stabilization/solidification to avoid mixing together  materials  that
can react with one another in a detrimental way.  In waste treatment, this
requirement of nonreactivity must also apply to the reagents  or materials
used in treatment.  Potential detrimental consequences  of  mixing wastes
include:

     a.  Heat generation.

     b.  Release of toxic materials or flammable gases.

     c.  Fire or explosion.

Table 3-1 summarizes some typical reactions that could  occur  during  hazard-
ous waste treatment and handling.
                                       27

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     Many treatment systems require the mixing of  reactive waste  and/or
reagents of many kinds to produce a more stable or nonreactive  product.
This process requires great expertise and knowledge of  the precise  nature
and composition of the waste and of the waste reagents.   Such mixing  is
typically carried out in treatment systems which accept diverse types of
waste from diverse sources.

     In addition to waste incompatibility problems, it  is also  necessary to
note incompatibility of waste and stabilization/solidification  materials
over both long and short time periods.  Though many reactions between waste
materials and treatment reagents occur very slowly, the result  may  be accel-
erated deterioration of the treated waste and loss of containment proper-
ties.  Table 3-2 summarizes major incompatibility  problems that can be
encountered with various waste solidification/stabilization  techniques.
Most of the difficulties are similar to those found in  any hazardous  waste
handling operation.  For example, without great care and  knowledge, oxi-
dizers and easily oxidized materials should not be mixed; strong  acids, and
strong bases should not be combined; cyanides and  sulfides should not be
acidified; and organic solvents must be isolated from soluble materials they
attack or dissolve.

     Some solidifying reagents may never set or harden  if the wastes  con-
tain inhibiting materials.  Silicate polymer reactions  can be slowed  by
organics or high concentrations of certain metals.  Organic  polymers  can be
broken down by solvents, strong oxidizers, or strong acids  (Table 3-3).
Organic polymers are also degraded by ultraviolet  radiation  (exposure to
sunlight).

     Care must be taken in all systems requiring the mixing  of  hazardous
wastes with other waste materials or with reagents required  for solidifica-
tion or stabilization.  In general, the silicate-based  (cement  or pozzolan)
containment systems are most tolerant to a wide variety of wastes,  both
inorganic and organic.

3.4  TESTING THE PHYSICAL PROPERTIES OF STABILIZED WASTES

     The physical properties of the waste are modified  by the stabilization/
solidification process.  The end product of many treatment processes  is a
solid block resembling low-strength concrete, which can be subjected  to
standard tests of physical properties so that its  durability under  field
conditions can be predicted  (3-1).  Some processes produce a friable  or
soil-like product that must be subjected to tests  more  typically  used for
soil-cement  (3-2).  Prediction of chemical containment  characteristics of
these stabilized wastes from physical properties is much  more difficult  than
prediction of long-term physical characteristics.

     The primary aims of physical testing of  treated  and  untreated  wastes
are  to  (1) determine particle size distribution, porosity, permeability and
wet  and dry densities,  (2) evaluate their bulk  properties,  (3)  predict the
reaction of a material to applied stress in embankments,  landfills, etc.,
and  (4) evaluate durability.  A variety of physical properties  tests  are
                                       30

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     TABLE 3-3.   LONG-TERM CHEMICAL RESISTANCE OF ORGANIC POLYMERS (RESINS)
                           USED IN SOLIDIFICATION*

Chemical
Acetic acid 50%
Benzene
Butadiene
Carbon tetrachloride
Chloroform
Chromic Acid
Cresol
Dichlorobenzene
Diethyl ether
Gasoline
Metallic salt sol.
Sulfuric acid (cone.)
Trichloroethane

Conventional
polyethylene
Excellent
Poor
Not resistant
Poor
Poor
Excellent
Poor
Poor
Not resistant
Poor
Excellent
Moderate
Not resistant
Resistance of resins
Linear
(high density)
polyethylene
Excellent
Moderate
Not resistant
Moderate
Moderate
Excellent
Poor
Poor
Not resistant
Moderate
Excellent
Moderate
Not resistant

Polyvinyl
chloride
Moderate
Not resistant
Not resistant
Moderate
Not resistant
Excellent
Poor
Not resistant
Not resistant
Poor
Excellent
Not resistant
Not resistant

*  Adapted from information given by Nalge Chemical Company.
                                      32

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              TABLE  3-4.   STANDARD TESTS  OF  PHYSICAL  PROPERTIES
             Test
              Source
Bulk and dry unit weight

Unconfined compressive strength


Permeability

Wet/dry durability

Freeze/thaw durability
Appendix II of EM 1110-2-1906*

Appendix XI of EM 1110-2-1906 and
  ASTM Method D2166-66**

Appendix VII of EM 1110-2-1906

ASTM Method D559-57

ASTM Method D560-57
 *  See Reference 3-3.
**  See Reference 3-4.

applicable to treated and untreated wastes.   Five  standardized  tests  that
have been used in the past and for which some data are available  are  dis-
cussed briefly.  A complete description of  these testing  procedures can be
found in the sources listed in Table  3-4.

3.4.1  Bulk and Dry Unit Weight

     The bulk unit weight is  the weight  (solids plus water)  per unit  of
total volume of material mass, irrespective  of the water  content  (see
Table 3-4).  The dry unit weight is the ratio of the oven-dried weight  to
the total volume.  The volume of the  sample  tested is usually computed  from
measurements of a regularly shaped mass produced by molding  or  trimming.
The drying temperature used to obtain the dry weight of the  material  should
be specified.  Unit weights provide information for weight-volume relation-
ships and are used to compute earth pressure  or over-dirt pressure in con-
struction.  They are a measure of density and, indirectly, of void volume.

3.4.2  Unconfined Compressive Strength

     The unconfined compressive strength is  defined as the maximum unit
axial compressive stress at failure or at 15% strain, whichever occurs
first (see Table 3-4).  The unconfined compressive strength  test  is appli-
cable only to cohesive or cemented material.  To determine compressive
strength, a cylindrical specimen is prepared  and loaded axially.   The re-
sults are usually presented as a graph of compressive stress sustained  by
the sample versus strain.  The shear  strength of a cohesive  material  is
obtained by multiplying the unconfined compressive strength  by  0.5.   Shear
strength is an important factor in determining ultimate bearing capacity of
the treated waste, stability of the embankments formed from  solidified
wastes, and pressure against retaining walls  surrounding  waste  materials.
Figure 3-1 shows testing of jacketed materials.
                                      33

-------
Figure 3-1.  Compression testing of
             plastic-jacketed wastes.
               34

-------
3.4.3  Permeability

     Permeability can be defined as the ability  of  a material  to  conduct or
discharge water when placed in a hydraulic gradient  (3-3).   The permeability
of a material depends on various parameters,  including  density, degree  of
saturation, and particle size distribution.   Previous work has indicated
that two types of tests are needed for determining  permeability of  treated
and untreated sludges (3-2).  A falling head  permeability test can  be used
on raw sludges, and fixed sludges can be tested  using a modified  constant
head test in a triaxial compression chamber with back pressure used to
ensure complete saturation.  A complete description of  the two tests can be
found in the USAE Soil Testing Manual (3-3).  The permeability of a material
indicates the ability of the material to permit  or  prohibit  the passage of
water.  Permeability is an important factor in waste disposal because it
influences the rate at which contaminants in  the waste  may be  released  to
the environment.

3.4.4  Wet/Dry Durability

     The wet/dry durability test is used to evaluate the resistance of  soil-
cement mixtures to the natural weathering stress of wetting  and drying.   In
the test procedure (see Table 3-4), cured specimens are subjected to 12 test
cycles, each consisting of 5 hr of submergence in water and  42 hr of low-
temperature oven drying.  Each cycle is followed by  two firm strokes on all
surface areas with a wire scratch brush.  Test results  are generally ex-
pressed as weight loss after 12 wet-dry cycles or the number of cycles  that
cause sample disintegration, whichever occurs first.  Specimens that fail
this type of test cannot be expected to have  good long-term  containment prop-
erties for those processes that depend upon isolating the waste.  Figure 3-2
shows typical solidification test specimens after 4 wet-dry  test  cycles.

3.4.5  Freeze/Thaw Durability

     The freeze/thaw durability test is used  to  evaluate the resistance of
soil-cement mixtures to the natural weathering stress of freezing and thaw-
ing.  In the test (see Table 3-4), cured specimens  are  subjected  to 12  test
cycles, each consisting of freezing for 24 hr, thawing  for 23 hr, and two
firm strokes with a wire scratch brush on all surface areas.   Performance is
evaluated by determining the weight loss after 12 cycles or  the number  of
cycles that cause disintegration, whichever occurs  first.  Specimens that
lack freeze/thaw durability must be protected from  frost if  containment is
to succeed for those processes that depend upon  isolating the waste or
lessening its surface area.

3.4.6  Summary

     Some typical results of physical testing of stabilized  and untreated
industrial waste are listed in Table 3-5.  The data show that stabilization
processes generally increase density and strength,  and  decrease permeabil-
ity.  Note that many of the treated sampes lack  durability.  The most strik-
ing feature of these results is the treatment processes do not produce
                                      35

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products with similar physical properties.  The lime-based pozzolan products
are similar to low-strength concrete with high bulk and dry unit weights,
relatively high compressive strengths, and low permeability.  The  cement-
based, concrete-like product also has these same properties.  The  soil-like
product on the other hand had little increased strength and had increased
permeability.  Strength and impermeability would be of value if isolation  of
the waste constituents in a strong, monolithic block of material was  the
intent of the treatment process.  Dense, impervious products would be  ex-
pected to lose little pollutant to the environment because of the  decreased
surface area of waste that is exposed to the leaching medium.  The solidi-
fied blocks must be nearly impermeable to produce effective containment,
because even small volumes of water moving through the waste will  carry off
appreciable amounts of contaminants.  A large difference between bulk unit
weight and dry unit weight is indicative of a large amount of pore space
(void space), which allows for a high permeability and/or relatively  rapid
diffusion of materials from within the solidified waste.  Plastic  encapsula-
tion  (see electroplating waste in Table 3-5) yields the optimum result of
producing an impermeable material.  The plastic coating over the waste com-
pletely blocks water passage in or out of the waste so that the bulk  and dry
unit weights are identical, and the permeability is unmeasurably low  (i.e.,
the block is impervious).  Very little diffusion of material or flow  in or
out of this product is possible as long as the jacket remains intact.

     The process using patented additives to produce a soil-like material
attempts to stabilize the waste constituents using a different procedure.
Basically the process adjusts the pH to a preselected range and then  adds  an
ingredient (sodium silicate) that tightly binds the inorganic constituents
of the waste so that they will be held in the treated waste matrix.   The end
result is a soil-like waste mixture that has a high differential between
bulk and dry unit weights  (large amount of pore space), low strength,  and
relatively high permeability.  This system depends on precipitation and
adsorption phenomena to produce containment.

     Preliminary results indicate that either treatment system, physical
isolation or chemical immobilization, can be effective for specific waste
contaminants.  Physical properties alone are not effective in predicting the
ability of any treatment process to contain a particular waste type.   De-
tailed knowledge of the method of containment of a particular treatment
process and of the waste to be treated is necessary before the physical
properties have any predictive value.

3.4.7  Other Tests of Physical Properties

     Other physical tests may be appropriate for determining the suitability
of treatment processes for wastes with different or unusual properties or
for specialized applications of the final treated waste product.

Soil Tests—
     Additional soil analyses that might prove useful with  treated wastes
under special circumstances include tests for compaction, Atterberg limit,
triaxial compression, and  bearing capacity.  Compaction tests are  used to


                                      38

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determine the maximum unit weight or minimum void  ratio  that  can be  obtained
for a soil-like material.  The density of this material  has a maximum at  the
optimum water content.  A compaction test is generally conducted on  soils or
treated wastes to determine suitability for use  in a  landfill where  struc-
tures are to be placed on the site.

     Atterberg limit tests are used to determine the  water  content at the
boundaries between liquid and plastic states.  The tests are  applicable only
to fine-grained cohesive materials.  The water contents  are used to  estimate
properties such as compressibility, strength and swelling characteristics,
which provide an indication of how the material  will  react when stressed.

     Triaxial compression tests are used to determine the shear strength  of
soil-like materials under controlled drainage conditions.   The shear strength
provides an indication of the bearing capacity of  the material and the sta-
bility of embankments constructed of the material.  Bearing tests are com-
monly used to evaluate subgrades for pavements.  These tests  provide
structural settling data with regard to applied  load  for the  material being
tested.  Since some waste samples that appear stable  or  solid may liquefy if
vibrated, strength determinations should include a vibrated series of
specimens.

     One area of soils testing that has been generally ignored but that has
application for landfilling of treated sludge or waste is trafficability
testing.  Disposal of stabilized waste in any large quantities requires the
use of tracked and wheeled vehicles to move and  place the material.   It is
important to know what type of vehicle can be used on the material and what,
if any, curing time is required before a vehicle can  cross  it.   This infor-
mation can be obtained by performing cone penetration tests along with other
soil tests already discussed.  Most earthmoving  equipment companies  can
provide the information needed on their particular equipment  to complete
trafficability evaluations.

Concrete Tests—
     Of the additional concrete tests that are applicable to  soil-cement
mixtures, one test in  particular that might prove useful in  evaluating
stabilized waste for commercial use is a strength  versus curing time test.
In this test, a determination similar to the unconfined  compressive  strength
test is used to determine the compressive strength of the curing cement-
waste mixture.  Strength tests are generally conducted each day until maxi-
mum strength is reached.  Strength versus curing time tests are useful for
determining the necessary curing time needed for safe application of a load
to a material after placement.

     The problem noted with regard to sulfate reaction in stabilized
sludges indicates that a swelling test of the type used  with  concrete might
also be appropriate.  Standard swelling tests use  a sulfate solution (3-5).
A simple adaptation of this test can be made by  substituting  distilled water
for the sulfate solution used with concrete samples.  Significant changes
and dimensions and/or loss of strength and spalling indicates a failure.
                                      39

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     The additional testing procedures described above are useful  in  eval-
uating stabilized sludges that are to be used in special applications.   The
additional cost of these tests cannot be justified for routine  landfilling
operations.

3.5  CHEMICAL LEACH TESTING OF STABILIZED WASTES

3.5.1  General

     Chemical leach testing of wastes is a  technique  that is  used  to  examine
or predict the chemical stability of treated wastes when they are  in  contact
with aqueous solutions that might be encountered in a landfill.  The  proce-
dures demonstrate the degree of immobilization of contaminants  produced  by
the treatment process.  A great number of techniques  for leach  testing are
available  (3-6).  Unfortunately, no single  leach testing system can dupli-
cate the variable conditions that may be encountered  by landfilled treated
wastes.

     Most  test procedures are conducted at  temperatures (20°  to 25°C) and
pressures normally occurring in the laboratory.  The  major variables  en-
countered  in comparing different leaching procedures  are:

     1.  Nature of the leaching solution.

     2.  Waste-to-leaching solution ratios.

     3.  Number of elutions of leaching solution used.

     4.  The time of contact of waste and leaching solution.

     5.  Surface area of waste.

     6.  Agitation technique employed.

     There is no uniform opinion as to how  each of these variables should
be treated in a testing procedure  (3-7).

Nature of  the Leaching Solution—
     Ideally, the leaching solution employed in any testing procedure should
approach the actual fluid that is in contact with the wastes  in the landfill
environment.  Unfortunately, there is no way of developing a  single leaching
solution that represents all the varying conditions with regard to pH,
oxidation-reduction potential  (Eh), presence of chelating or  complexing
agents, etc. that might be present in a landfill.  The general  tendency  in
most investigations is to use an agressive  leaching solution  with  low pH and
low Eh to  simulate a the worst case landfill environment.

     Further practical restraints are placed on the composition because  the
test solution must be useful in an ordinary laboratory situation.   Prepara-
tions  that require handling under  inert gases or  that require reagents  that
cannot be  obtained in an adequately pure form without great expense are  not
                                       40

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appropriate for a generalized testing  system.  Most  investigators have se-
lected weakly acidic solutions such as  carbonic  acid (CO  -saturated water)
or acetic acid as leaching media  (3-7).

     Use of these mildly acidic leaching  solutions has  its  basis in the fact
that natural precipitation and soil waters  (which contain CO )  are mildly
acidic.  Simple acetate buffer systems  have  long been used  in estimating the
availability of trace metals in agriculture.   For example,  Morgan's solution,
an acetic acid-sodium acetate buffer,  is  routinely used to  assess availabil-
ity of metals in agricultural soils.   To  the extent  that  these  mildly acid
systems reflect increased solubility in rainwater or soil water, they repre-
sent the best compromise as a leaching  medium.   The  groundwater in a land-
fill (especially in a landfill containing only solidified industrial wastes)
may never reach the low pH observed in  the acetic acid-based solutions,  but
roots growing down into the waste could possibly reduce the pH  in their
immediate vicinity to levels similar to those  seen in acetic acid and
acetate buffer solutions.

Waste-to-Leaching-Solution Ratios—
     The decision as to the ratio of waste to  the amount  of leaching solu-
tion is always a compromise.  Obviously,  a waste can come into  contact with
an enormous quantity of leaching solution (rainwater, groundwater, etc.)
after disposal.  Where the waste-to-leaching solution ratio is  very large,
(1:1 or 1:2), common ion effects can reduce  the  solubility  of certain chemi-
cal constituents.  Smaller waste-to-leaching-solution ratios (1:5, 1:40) are
considered to be appropriate (3-6).

     In most cases, the practical restraints on  the  testing require that a
large enough volume of leaching liquid  be used to allow the analyses to be
performed at the low levels necessary  to  assure  the  health  and  safety of
persons coming into contact with a leachate  from the waste.   Thus if a level
of a toxic organic compound must be determined to part-per-billion levels,
several liters of leachate must be available from the test  procedure.

     The ability to generate a relatively large  volume  of leachate by run-
ning tests in duplicate or triplicate is  a very  practical asset in the
design of a testing procedure.

Number of Elutions of Leaching Solution Used—
     In most leachate testing, the initial samples of leachate  produced can
be considered to contain the maximum concentrations  of  potential contaminants
that will be observed in the test procedure.   The reason  is that the initial
leach liquid samples are exposed to the waste  while  the highest concentra-
tions of soluble contaminants are present on the fresh  waste surfaces.  Also,
the maximum amount of fine-grained solid  material (which  would  have a greater
inherent solubility because of its small  particle size) is  available in the
waste during the first elution.

Surface Area of Waste—
     The ideal testing system would expose a leaching solution  to the same
surface area that it would be exposed to  in a  landfill.   In the case of a
                                      41

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dense impermeable waste material, this surface area could  equal  only  the
boundary surface of a waste monolith.  In a loose, powdery material or  a
sludge, however, the surface area may be hundreds or  thousands of  times
greater than the boundary surface of the waste mass.

     One of the objectives of many waste solidification/stabilization
systems is to produce a monolithic mass with a minimum  surface area across
which loss of pollutants can occur.  Testing techniques that  call  for the  I/
waste to be ground to a powder destroy much of the advantage  produced by
solidification by these processes.  However, some processes are  designed  to
contain the waste even after being ground to a fine powder.

     A compromise is to test the coherence of a  solid waste by impact test-
ing and to use the monolith or fragmented monolith as a test  specimen.  This
approach offers the advantage of allowing a material  that  would  not normally
be landfilled in fragments to be tested in the configuration  in  which it  has
a minimum area for contaminant loss.  The major  disadvantages of such a
physical and chemical testing system are that:

     a.  The exact stress that should be applied to fracture  a coherent
         waste specimen as it might be fractured during landfilling or  com-
         paction cannot be accurately determined for  all cases.

     b.  The surface area of the test specimen cannot be known with any
         precision after the specimen has been fragmented. This is impor-
         tant if rate of transfer of contaminant per  unit  surface  area  is
         to be considered.

     c.  Physical testing of solidified/stabilized materials  indicates  that
         wetting/drying and freezing/thawing cycles can produce  rapid dis-
         integration of many treated wastes.  In many cases this fragmenta-
         tion may be more complete than simply cracking the specimen  in
         impact test apparatus.

     d.  The variation in fracture patterns between specimens of the  same
         waste introduces another level of variability  into the  testing
         procedure and reduces the repeatability of the test.

Agitation Employed—
     The agitation of test samples during leaching or the stirring of the
leaching solution has been advocated to permit more rapid equilibrium to
occur between the specimen and the leaching solution.   However,  there is  no
real analogy in nature for an agitated leaching  solution in contact with  a
solidified waste.  In most cases where the waste would  be landfilled, the
water or leachate in contact with the waste would be  stationary  or flowing
very slowly so that effective diffusivities characteristics are  of prime
importance.

     The major objection to agitating or mixing  the leachate  and solid
wastes is that mixing or shaking can grind the test specimen  to  smaller
pieces, thereby increasing the surface area exposed to  the leaching solution
and invalidating the test.

                                      42

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3.5.2  The EPA Extraction Procedure  (EP Toxicity  Characteristic)

     The EPA extraction procedure  (EP) is the only  leach  testing  system
currently proposed by EPA as a definitive part of the procedure for  the
identification of hazardous wastes (3-8).  Analysis of waste materials  can
be used to demonstrate the toxicity  of wastes, but  no simple test exists  to
show the degree to which these hazardous materials  will be  released  into  the
surroundings.  The goal of the EP is to determine the amount of contaminant
that is released under circumstances approaching  those that occur during  the
improper management of hazardous wastes.  The EP  involves exposure of  the
waste to a mild acid leaching solution.  The EP can be considered an aggres-
sive procedure for stabilized/solidified waste because it simulates
the environment to which the wastes  would be exposed if they were placed  in
a municipal landfill and saturated with landfill  leachate.  In cases where
the stabilized/solidified wastes are cast in large  monolithic masses,  cer-
tain minor modifications of the test procedure are  required.  Details  of  the
Extraction Procedure and its associated tests are discussed in Section 7.

3.6  EFFECTS OF BIOLOGICAL ATTACK ON TREATED WASTES

     In long-term containment of treated hazardous  and toxic wastes, biologi-
cal attack can be a major problem.   Biological attack can occur by direct
utilization of some solidification material  (such as UF resin) as a  substrate
for bacterial growth, or by the biological production of  acid materials that
can attack and corrode treated wastes.

     Columbo and Neilson (3-9) approached the problem of  possible direct  bio-
degradation of solidification matrix materials by measuring the total  amount
of organic carbon released into leaching waters.  Of the  four solidification
materials studied (Portland Type II  Cement, Urea-Formaldehyde  (UF) resin,
asphalt, and vinyl ester-styrene) the UF resin showed the greatest problem
with organic carbon release.  In an  18-day leaching program, a 211.7 g  sample
released 4.48 g of carbon.  No other solidification material approaches this
carbon release.  UF is generally conceded to be biodegradable.

     Other biological reactions can  affect solidified wastes indirectly.
For example, if wastes containing metallic sulfides are incorporated in a
cement matrix, reactions similar to  those occurring in the  production  of
acid mine drainage can occur.  The sulfides can oxidize to  sulfate and  pro-
duce sulfuric acid, which can attack and dissolve concrete.  This type  of
reaction occurs during the oxidation of pyrites and amorphous iron sulfides.
Atmospheric oxygen is necessary for  this reaction to proceed, and therefore
such reactions typically occur at the top of the  saturated  zone in sulfide-
rich landfills or waste piles.

     Plant roots are another source  of acid that  can remobilize wastes.
Root hairs typically discharge carbon dioxide into  surrounding water and
create a mild acid (carbonic acid) that is capable  of putting many toxic
metals into solution as bicarbonates.  Organic acids released by  decaying
roots can also cause corrosion of some waste materials, particularly those
solidified with a lime or cement-based process.
                                      43

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3.7  EFFECTS OF CURING AND AGING PROCESSES ON TREATED MATERIAL

     Curing and aging processes affect various treated  (solidified) wastes
in widely different ways.  Some polymeric materials add linkages during  cur-
ing and become stronger and less prone to leaching.  In other polymers,
where the waste is not an integral part of the structure,  separation  of
solid and aqueous phases can occur.

     Examples of these different effects can be seen in the  contrasts  between
cementitious (silicate) solidification systems and UF systems.  Moore  and
others (3-10) demonstrated that for cementitious systems less leaching was
observed when cement-based samples had been cured more  than  100 days.  The
conditions of curing were also important.  Specimens cured under humid con-
ditions (where polymerization would be accelerated) were less leachable  than
samples that were allowed to dry during curing.

     In contrast to cement-based systems, UF solidification  results in the
formation of a weep water that is not bound into the polymer structure.
Aging of this material produces shrinkage and additional excess water  (3-11).
Containment of waste decreases with aging.

     Other waste treatment systems that involve bitumen-based or water ex-
tensible polymer systems may also show long-term curing changes, but  no  data
are currently available to demonstrate whether aging/curing  effects will be
detrimental to waste containment properties.

     Obviously, where encapsulation systems use a surface  coating  of  polymer,
aging effects will be especially critical.  If isolation depends on the  in-
tegrity of a polyethylene or organic polymer jacket, any weaking or embrit-
tlement will severely compromise waste containment  (3-12).

     Each proposed treatment system will require testing after aging  to
assure long-term waste containment.

3.8  ECONOMIC CONSIDERATIONS OF TREATMENT OPTIONS,

     Most waste materials that are currently being considered for  disposal
have no present value, and thus all solidification/stabilization costs repre-
sent additional expenses to be added to the ultimate cost  of the product or
service sold.  A complete economic analysis must consider  costs of waste
transportation, materials and equipment required for stabilization/
solidification, skill levels of treatment plant operators, fees or royalties
for use of patented processes, and cost of transporting and  landfilling
treated wastes.  This type of analysis often must be undertaken oa^a^case-
by-case basis.  However, to obtain an initial impression of  the usefulness
of different waste treatment systems now and in the future,  it is  possible
to restrict economic considerations to present and projected costs for mate-
rials, equipment, and energy.  In most treatment systems,  the cost of  mate-
rials required is the major item regulating present and projected  costs.
Table 4-6 outlines the present and future economic considerations  for major
waste stabilization/solidification systems.


                                      44

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     As shown in Table 3-6, the silicate-based  systems  (cement-based  and
pozzolanic) operate with the least expensive materials and have  the most
stable pricing structures for raw materials.  The organic polymer  systems
(including bitumen) have the most easily disturbed raw material  costs be-
cause the prices of raw materials used in these  systems are  tied to the
price of oil.  At present economic considerations appear to  be heavily
weighted toward low-temperature silicate systems and against organic
polymers.
                                      45

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                                  REFERENCES

 3-1.  Mahloch, J. L., D. E. Averett, and M. J. Bartos.  Pollutant Potential
       of Raw and Chemically Fixed Hazardous Industrial Wastes and Flue  Gas
       Desulfurization Sludges.  EPA-600/2-76-182, U. S. Environmental Pro-
       tection Agency, Cincinnati, Ohio, 1976.  117 pp.

 3-2.  Bartos, M. J. and M. R. Palermo.  Physical and Engineering Properties
       of Hazardous Industrial Wastes and Sludges.  EPA-600/2-77-139, U.  S.
       Environmental Protection Agency, Cincinnati, Ohio,  1977. 87 pp.

 3-3.  Engineering and Design - Laboratory Soils Testing.  Engineering Man-
       ual, EM 1110-2-1906, U. S. Department of the Army,  Washington, D.  C.,
       1970.

 3-4.  Annual Book of ASTM Standards, Part II.  American Society for Testing
       and Materials, Philadelphia, Pa., 1973.  874 pp.

 3-5.  Bogue, R. H.  The Chemistry of Portland Cement, 2nd ed. Reinhold
       Publishing, New York, N. Y., 1955.  793 pp.

 3-6.  Lowenbach, W. A.  Compilation and Evaluation of Leaching Test Methods.
       EPA-600/2-78-095, U. S. Environmental Protection Agency, Cincinnati,
       Ohio, 1978.  102 pp.

 3-7.  Anderson, M. A., R. K. Ham, Rainer Stegman, and Robert Stanforth.
       Test Factors Affecting the Release of Materials from Industrial
       Wastes in Leaching Tests,  pp. 145-168.  In:  Pojasek, R. B., ed.
       Toxic and Hazardous Waste Disposal, Vol. 2, Ann Arbor Science Publ.
       Inc., Ann Arbor, Mich., 1978.  259 pp.

 3-8.  U. S. Environmental Protection Agency.  Hazardous Waste Management
       System.  Federal Register, 45(98):33063-33285.  May 19, 1980.

 3-9.  Colombo, P. and R. M. Neilson, Jr.  Properties of Radioactive Wastes
       and Waste Containers Progress Report No. 5, April-June 1977.  Publ.
       No. BNL-NUREG-50763, Brookhaven National Laboratory, Upton, N. Y.,
       1977.  43 pp.

3-10.  Moore, J. G., H. W. Godbee, and A. H. Kibbey.  Leach Behavior of
       Hydrofracture Grout Incorporating Radioactive Wastes.  Nuclear Tech-
       nology, 32:39-52, 1977.

3-11.  Columbo, P. and R. M. Neilson, Jr.  Properties of Radioactive Wastes
       and Waste Containers.  BNL-NUREG - 50692, Brookhaven National Labora-
       tory, Upton, N.Y., 1977.  53 pp.

                                      47

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3-12.  Lubowitz, H. R. , R. L. Denham and G. A. Zakrzewski.  Development of a
       Polymeric Cementing and Encapsulating Process for Managing Hazardous
       Wastes.  EPA-600/2-77-045, U. S. Environmental Protection Agency,
       Cincinnati, Ohio, 1977.  167 pp.

-------
                                  SECTION 4

             ASSESSMENT OF CURRENT DATA ON PHYSICAL AND CHEMICAL
                        PROPERTIES OF TREATED WASTES
     Recent interest in chemical stabilization of hazardous  industrial
wastes is beginning to bring about the accumulation of data  from  studies
dealing specifically with these solidified waste products.   Most  information
found in this section comes either from a few government-sponsored  studies
or from the vendors of waste treatment systems themselves.   The results
presented here are intended to be representative of the kinds  of  tests  that
are commonly performed and the ranges of data that are typically  found.
Many of the data have been transformed into common units  to  give  uniformity
and comparability to the results.

4.1  EXISTING DATA ON PHYSICAL PROPERTIES OF TREATED WASTES

     Because no physical testing regime specific for solidified waste has
been designed, most tests performed are those commonly used  to determine  the
properties of soils and concrete.  Thus, the test results  do not  always
represent the best information needed to judge the containment capability  of
the treated waste, but they are useful in making comparisons with other ma-
terials whose properties are described in the literature.  The incompleteness
of the data and the variability in the testing techniques  make correlation
of physical properties with leaching characteristics very  difficult.  Cor-
relations should be made only in cases where the physical  properties are
known to be determined on replicates of the actual samples used in  the  leach-
ing test.  Details of the typical test and interpretation  of the  results are
discussed in Section 3.4.

     Another important consideration in discussing the physical properties
of treated wastes is that the physical properties that are important to the
containment success of the different types of treatment processes vary
greatly with the treatment type.  For instance, the unconfined compressive
strength of a treated product is meaningful only for those processes that
limit contaminant loss by producing a solid monolith.  Processes  that produce
soil-like or plastic, spongy masses or encapsulates require  completely  dif-
ferent testing regimes.  Even typical soil tests such as Atterberg  limits or
undrained shear strength may not have an important bearing on  containment
properties of the soil-like products of some treatment systems.   The physi-
cal tests that are indicative of treatment success are process-specific and
must be determined for each individual case.

     Unconfined compressive strength (or analogous measurements)  and permea-
bility are most commonly reported for the treatment processes  that  produce

                                     49

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monolithic products for which high strength values and  low permeabilities   ,-
are said to be indicative of good containment^  Compressive  strengths  of  10
to 10  N/m  and permeabilities of 10   to  10   cm/sec are  not  unusual  for
concrete-based treatment systems  (Table 4-1).  Organic  admixture  systems
generally are plastic  (with low strength)  and vary from highly permeable  to
impermeable depending on the kinds and amounts of additives  used.   The treat-
ments that produce clay or soil-like products cannot be tested using the
physical testing procedures designed for concrete-like  products.   These
products usually have relatively high permeability and  depend  on  containing
the pollutants by binding them inside a molecular matrix.  A summary of the
kinds of physical tests reported by the major vendors in the field are pre-
sented in Table 5-1 along with the process type and comments of performance
in leach tests.

     The details of the tests that are performed are quite important and
should be indicated for each test made.  Table 4-2 illustrates the changes
in the unconfined compressive strength of  samples of treated products  made
with varying amounts of cement and water content of the particular sludge
being fixed.  Note that a 10% to  15% change in the water content  will  change
the compressive strength of the product several fold.   Small changes in the
amounts of impurities or the sludge pH can also have profound  effects  on  the
properties of the final product.

     A comprehensive study of physical and engineering  properties of treated
and untreated flue-gas cleaning and hazardous industrial sludges  has been
performed by the U. S. Army Engineers, Waterways Experiment  Station (WES)
(4-1, 4-2, 4-3).  The same treated and untreated sludge samples were also
used in several leaching tests, some of which are still in progress.   Five
flue-gas cleaning sludges and five hazardous industrial sludges were treated
by up to seven different solidification/stabilization vendors. The wide
variety of final products made it difficult to choose which  physical and
engineering property tests to run.  Physical property tests  that  could be
run on all treated sludges were specific gravity, water content,  void  ratio,
velocity, bulk unit waste, and dry unit waste.  Tests for  engineering  prop-
erties included compaction, unconfined compression, modulus  of elasticity,
permeability, and durability.  Wet-dry and freeze-thaw  cycle tests were also
performed.  Results reported to date for the leaching tests  on the same batch
of samples indicate that none of  the physical properties tested were of
significant value in estimating loss rate  in all leaching  tests.  The results
of the physical tests appeared to useful only for predicting handling  char-
acteristics or disposal site requirements.  The tests might  be useful  pre-
dicting the success of a specific treatment system on a particular waste
type, but were not valid when comparing between treatment  types.

4.2  EXISTING DATA ON  CHEMICAL PROPERTIES  OF TREATED WASTES

     Results of leaching tests are commonly reported by vendors of waste
treatment systems.  However, the  protocols of leaching  tests vary widely,
from a 1-hr unstirred, distilled-water leaching test on undisturbed treated
waste samples to extended, repeated leaching of ground  samples by aggressive
leaching solutions.  Some vendors report results of field  tests.   Table 4-1
                                      50

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lists typical types of leaching tests and results from the major vendors of
waste treatment systems.

4.3  CORRELATION OF PHYSICAL AND CHEMICAL PROPERTIES

     The great variety of treatment techniques makes it difficult to  consis-
tently correlate physical and chemical properties in treated materials.  The
asphaltic materials and the plastic-jacket encapsulates are imprevious
solids and both show excellent waste retention.  When admixes of wastes and
pozzolan or Portland cement are attempted the results become less easily in-
terpreted. Some admix systems depend on chemical binding and adjustment of
pH, thus impermeability, increased strength and decreased void space  are not
as important as the chemical composition and potential binding reactions in
the mix.

4.4  INTERPRETATION OF PHYSICAL AND CHEMICAL DATA

     Interpreting the chemical and physical data collected on stabilized/
solidified wastes is very complex.  How much waste containment must a sta-
bilized specimen exhibit?  How strong physically must a treated waste mate-
rial be?  Absolute guidelines may be set, or the best judgment of regulatory
officials may be used.  Two major methods of data interpretation exist:  At-
tempting to predict environmental impact, or using rigid standards for waste
materials that ensure some degree of containment regardless of surrounding
conditions.

     No presently required chemical leach test is designed to predict the
ultimate containment of treated toxic waste, but test protocols developed
for the nuclear waste industry can be employed to model waste containment
(4-4, 4-5, 4-6).  The problem of radionuclear waste escape from solids
formed using matrices of cement, asphalt, ceramic, or glass media can be
modeled using expressions that take into account diffusion and concentration-
dependent dissolution.  Details of tests based upon the predictive Inter-
national Atomic Energy Agency testing procedure are given in Appendix B and
further discussion of predictive models is given in Section 6.
                                      54

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                                 REFERENCES
4-1.  Mahloch, J. L., D. E. Averett and M. J. Bartos, Jr.  Pollutant Poten-
      tial of Raw and Chemically Fixed Hazardous Industrial Wastes and Five
      Gas Desulfurization Sludges—Interim report.  EPA-600/2-76-182, U.  S.
      Environmental Protection Agency, Cincinnati, Ohio.   1976.   105 pp.

4-2.  Bartos, J. J., Jr., and M. R. Palermo.  Physical and Engineering Prop-
      erties of Hazardous Industrial Wastes and Sludges.   EPA-600/2-77-139.
      U. S. Environmental Protection Agency, Cincinnati, Ohio.   1977.  77
      pp.

4-3.  Thompson, D. W. and P. G. Malone.  Physical Properties Testing of Raw
      and Stabilized Industrial Sludges.  Pp. 35-50.  In:  Pojasek, E. B.
      (ed.).  Toxic and Hazardous Waste Disposal, Vol. 2,  Ann Arbor Press.
      Ann Arbor, Mich.,  1979, 259 pp.

4-4.  Godbee, H. W., and D. S. Joy.  Assessment of the Loss of Radioactive
      Isotopes from Waste Solids to the Environment.  Part I  Background  and
      Theory.  Publ. ORNL-TM-4333, Oak Ridge National Laboratory, Oak Ridge,
      Tenn., 1974.  57 pp.

4-5.  Moore, J. G., H. W. Godbee, A. H. Kibbey, D. S. Joy.  Development of
      Cenentitious Grouts for the Incorporation of Radioactive Wastes.  Part
      I  Leach Studies.  Publ. ORNL-4962, Oak Ridge National Laboratory,  Oak
      Ridge, Tenn., 1975.  116pp.

4-6.  Moore, J. G. Development of Cementitious Grouts for  the Incorporation
      of Radioactive Wastes.  Part 2.  Continuation of Cesium and Strontium
      Leach Studies.  Publ.  ORNL-5142, Oak Ridge National Laboratory, Oak
      Ridge, Tenn., 1976.  144pp.
                                     55

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                                  SECTION 5

             DESIGN CONSIDERATIONS FOR SOLIDIFIED AND STABILIZED
                          WASTE DISPOSAL FACILITIES
     Disposal of treated wastes is subject to the same regulatory and  oper-
ational constraints and considerations as the disposal of any  other waste
stream, even though the end product is nonhazardous and/or easily managed  or
transported.  This section addresses special aspects of  treated wastes that
may be important to the disposal operation, and the general aspects and
alternatives of waste disposal under currently proposed  regulations and
technology.  The major emphasis of this section concerns nonhazardous  dis-
posal technology and regulations under RCRA definitions  and procedures
necessary to avoid the more rigorous hazardous waste disposal  requirements.

5.1  SPECIAL CONSIDERATIONS FOR HANDLING AND DISPOSAL OF STABILIZED/
     SOLIDIFIED WASTES

     Chemical treatment usually strives to produce a solid monolith in order
to exclude leaching waters from the bulk of the waste materials.  The  larger
the treated waste block, the greater is the proportion of the  waste that is
isolated from environmental interactions.  The treated waste may also  require
secondary containers such as drums or tanks.  Some treated wastes present
unique problems to the typical waste handling and compacting equipment de-
signed for loosely packed refuse or semisolid sludges.   The solid block
should be formed and covered with a minimum of fracturing to retain the ben-
efits of treatment.

     A very common practice (especially for hazardous sludges)  is to  combine
the treatment and disposal operation.  In this method, the wastes are  trans-
ported to the facility in their original  (and perhaps hazardous) condition,
where they may undergo chemical treatment.  The wastes are mixed with  the
appropriate chemical additives and pumped directly to the waste disposal area
as a semisolid slurry that solidifies in place into a single monolithic mass.
As yet, no specific regulations have been written concerning this type of
operation, but it appears that if hazardous wastes are involved, the  treat-
ment phase of the operation would be covered by the more rigorous hazardous
waste regulations with regard to storage and treatment operations.

     All treated wastes are susceptible to breakdown and release of  the
contained wastes if they encounter an aggresive environment in the waste
disposal site.  Even mildly acid environments will slowly breakdown most
cement- and pozzolan-treated wastes.  High sulfate concentrations in  the
contacting waters will cause surface spalding and structural breakdown of


                                     56

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cement-based products.  Organic solvents, and even oils and  greases,  can
cause loss of integrity in asphalt-based treated wastes.  Strong  oxidants
can cause breakdown of many organic-based treated wastes.  Even glass-
containing wastes can be etched and devitrified in strongly  alkaline
environments.

     Sanitary landfills are currently being studied as depositories of  non-
hazardous treated wastes, since they represent a common and  well  understood
disposal system  (5-1).  Although long-term results are not available, it now
appears that the increased rate of dissolution of the cement- and pozzolan-
treated wastes is more than offset by the large exchange capacity of  the
cellulosic residue in the municipal waste.  Little heavy metal release  to
the surrounding environment occurs.  Attenuation of the pollutants by the
municipal refuse may be only temporary however, since after  the bulk  of the
organic material is broken down, release may occur.  Sanitary landfills are
best presumed to be unsuitable for disposal of treated wastes.

5.2  DESIGN FACTORS FOR HAZARDOUS WASTE LANDFILLS

     Treated wastes that meet the EPA criteria for hazardous waste must be
disposed of in a landfill that has been designed and approved for handling
hazardous solid waste.  In general terms, hazardous waste landfills must
provide complete, long-term protection of the quality of surface  and  sub-
surface waters from any of the hazardous constituents disposed therein  and
from any hazards to public health and the environment.  Such sites must be
located or engineered to avoid direct hydraulic continuity with surface and
subsurface waters.  Subsurface flow of groundwater into the  disposal  area
must be prevented.  Leachate generation shquld be avoided; any produced must
be collected and treated.  Monitoring wells must be installed, and a
sampling and analysis program must be designed and approved.  These require-
ments would also be desirable for typical, sanitary landfills.  The primary
difference involves the degree of concern and care, and the  record keeping
that must be involved where hazardous materials are involved.

     The state of the art for predicting discharges or releases from  land-
fills is poor.  Therefore EPA states in their proposed rules that the only
option available to insure protection of human health and the environment is
to prescribe design and operating standards for hazardous waste landfills
that provide maximum containment.  An inert, essentially impermeable  liner
is required at all hazardous waste landfills.  Furthermore,  in localities
where climatic and natural geologic conditions are such that leachate
buildup might be expected (where evaporation does not exceed precipitation
by 20 in. or more), an active leachate collection system is  required  so that
any leachate generated can be removed and treated.  Landfills located over
an underground drinking water source must install groundwater and leachate
monitoring systems and provide for up to quarterly sampling  and analysis of
specified parameters.  Sampling, analysis, and record keeping are required
for at least 20 years after closure of the landfill.  Exact  location  of each
hazardous waste (with respect to permanently surveyed benchmarks) and the
dimensions and compositions of the waste must be recorded and kept available
for inspection.
                                     57

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     EPA has proposed to restrict hazardous waste landfills from accepting
ignitable, reactive, or volatile wastes, or wastes that are bulk liquids,
semisolids, or sludges.  Liquid wastes in containers are prohibited but
liquids may be solidified in the container.  Bulk liquids can be fixed to
meet regulations.

5.3  USE OF LAND TREATMENT OF BIODEGRADABLE INDUSTRIAL WASTES

     Landfarming incorporates biological, chemical, and physical processes
of the upper soil horizons to effectively treat biodegradable industrial
wastes.  Selection, deposition, and postdepositional care must be adminis-
tered to maximize the effectiveness of waste degradation.  Disposal of
hazardous waste by landfarming may require pretreatment to eliminate  com-
bustion, reaction, or volatilization hazards.  Such treatment must result in
waste attributes conducive to the landfarming degradation processes.

     Similarities between this recycling of waste products and agricultural
farming all depend on planning and readily available, dependable, large-scale
equipment.  Combined agricultural techniques and landfarming of wastes can
result in improved land surface and soil characteristics, but the primary
objective is to dispose of waste continuously while maintaining or improving
the soils disposal efficiency for long-term usage.

     The densities and makeup of microbial populations vary with soil depth
and geographic location.  Geographic location also affects the seasonal dura-
tion and intensity of microbial activity.  The surface or near-surface dep-
osition of waste materials and mixing by conventional plow techniques exposes
concentrated waste material to large populations of microbes.

     Whether waste material is deposited on or beneath the soil surface is
determined by many factors such as the character of the waste, the microbes,
and the soil.  The function of the created waste-soil system is to produce
harmless volatiles, water soluble components, and decomposition products
available for uptake by vegetation.  Absorption of waste components by
mineral constituents of the soil must be avoided or the storage capacity
will eventually be reached and waste will be transmitted to groundwater
systems.  Depending on future site use, the landfarm can become a repository
of nonbiogradable materials, although such is not the purpose of a landfarm.
Pretreatment could provide nonbiodegradable material in a fixed form, pos-
sibly improving soil texture.

     Although the interactions among the soil constituents and waste  mate-
rials are complex, a list of general factors is given as follows:

      Temperature
      Moisture content
      pH
      Inorganic nutrients
      Oxygen availability
      Chemical composition of wastes
      Physical characteristics
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     The requirements for landfarming delineate environmental  concerns  pri-
marily related to water quality.  The landfarm must not have direct contact
with surface water or groundwater systems.  Erosion problems are  generally
not associated with landfarm areas because of restrictions posed  by surface
slope requirements.  However, any direct exposure of waste materials by ero-
sion must be considered.  Subsurface geology must prevent possible ground-
water contamination.  The surface slope must be sufficiently steep to prevent
ponding, but it must be gentle enough to prevent erosion.  The soil pH  must
be above 6.5 to prevent leaching of toxic metals.  Soil characteristics
throughout the site must be ascertained before, during, and after the site
is in active use.  This requirement establishes that the soil  has been
returned to an equivalent preexisting condition before closure.   Ignitable,
reactive, volatile, and incompatible wastes are not permitted  in  a landfarm
disposal system.  Some treated waste may prove to be suited to landfarming
if release of degradable compounds occurs at a rate comparable to their
destruction.  The technical resource document on Design and Management  of
Hazardous Waste Land Treatment Facilities (5-2) should be consulted for
further detail.

5.4  OPERATION AND MANAGEMENT OF DISPOSAL FACILITIES FOR TREATED  WASTES

     Many of the listed operational procedures discussed below are not  now
required for waste disposal facilities that are permitted to accept only
nonhazardous waste.  However, because most treated wastes would be catego-
rized as hazardous if they were not treated, procedures suitable  for hazard-
ous waste should be followed insofar as possible.  In the case of long-term
instability of the treated product, such precautions may prevent  environmen-
tal or groundwater degradation in the vicinity of the disposal site.  Most
procedures protect the operators of the disposal site as well  as  the general
public, and they can be accomplished with relatively small expense.  EPA's
position at this time is that treatment of any kind does not reduce the need
for a complete monitoring program.

5.4.1  Monitoring of Ground and Surface Waters

     The most frequent and serious environmental impact in the disposal
facility is also the most easily overlooked and most expensive to rectify—
that of losing leachate and pollutants to the groundwater.  Monitoring  of
the groundwater quality to ascertain whether pollutants are being lost  from
the disposal sites is the only method to be certain that no hazardous con-
stituents are being lost.  Monitoring should begin before opening of the
site to provide baseline data on the water quality in the area.   Ideally,
background samples should be taken throughout all hydrological seasons, as
considerable variation can occur within the year.

     Monitoring wells should be placed both up and down the groundwater
gradient from the disposal site.  Changes in the overall groundwater quality
in the area would not be seen equally in water samples from all wells.   Pol-
lutants from the disposal site itself should only show up in the  water  sam-
ples from wells down the groundwater gradient.
                                     59

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     Any elevated or abnormal concentrations should  immediately be  double-
checked with new water samples so that immediate remedial action  can be
taken.  A quick response to stop the source of  the leachate  infiltration  is
always cheaper and more effective than efforts  at cleaning up an  aquifer
after extensive pollution has occurred.

5.4.2  Gas Monitoring

     Landfills containing putresable materials  produce  large amounts of
methane and carbon dioxide.  Other gases  (hydrogen,  ammonia, hydrogen  sul-
fide, etc.) can be produced in appreciable quantities from particular  wastes
typically found in some landfills.  These reactive gasses can migrate  and
attack treated wastes causing a greatly increased loss  of constituents.
Depending on the geology and soil permeabilities at  the site, gases can
migrate long distances underground and accumulate under any  structures on
or near the disposal site.  Explosive gases, especially methane,  should be
monitored.  Toxic or asphyxiating gases should  also  be monitored  on a
regular basis with appropriate instruments.  The presence of such gasses
should bring about a reassessment of the  containment properties of  the
treated wastes.

     Gas migration through the soil is especially prevalent  in sandy,
permeable soils and in rainy periods as the influx of rainwater into the
soil forces gases into the surrounding areas.   Landfill gases are elusive,
and concentrations can vary greatly at the same sampling point over the
course of a few hours or between simultaneous sampling  at two adjacent
sampling points.  Areas with stunted or dying vegetation should be  checked
as likely areas of gas migration and/or collection.
                                      60

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                                 REFERENCES

5-1.   Myers, T.  E., and others.  Chemically Stabilized Industrial Wastes
      in a Landfill Environment.  Paper presented at 6th Annual Solid
      and Hazardous Wastes Research Symposium, Chicago, 111., March  17-20,
      1980.

5-2.   Brown, K.  W.  1980.  Design and Management of Hazardous Waste  Land
      Treatment  Facilities.  SW-874.  Office of Solid Wastes, U. S.  Environ-
      mental Protection Agency, Washington, D.C.  In press.
                                     61

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                                  SECTION 6

             STEPWISE EVALUATION OF STABILIZED/SOLIDIFIED WASTES
     In any waste disposal operation that involves a treatment such as
stabilization/solidification applied to a waste and ultimate land disposal
of the solid product, a number of considerations immediately arise:

     a.  Is the waste still ignitabile, reactive, or toxic?


     b.  What is the maximum toxic hazard presented by the solidified waste
         under normal conditions?

     c.  Will the stabilized/solidified material remain in a solid condition
         (with low permeability) in the disposal site?

     d.  What is the best estimate of leach losses over a long term  (i.e.
         100 years)?

     e;  What are the operating plans at the site selected?

     All of these questions are important in judging the acceptability  of a
hazardous waste disposal operation.  Unsatisfactory answers to any one  of
these questions would require revision of the disposal program.

     •The evaluation procedure outlined in this section uses examples from a
common case—disposal of a waste that has been treated using a cement-based
or pozzolan system for shallow land burial.  The procedure outline may
require modification for other treatment systems where plastic incorporated
waste materials are produced or where secondary containers such  as drums are
employed.  Parts of this section are based upon EPA's Hazardous  Waste
Management System; Part III, Identification and Listing of Hazardous Waste
(6-1).

6.1  STEP 1.  EVALUATION OF HAZARDOUS NATURE OF TREATED WASTE

6.1.1  Determination of Ignitability.

     To be classified on non-hazardous, the treated waste must not be  ignit-
able and must not cause fires through friction, absorption of moisture, or
spontaneous chemical changes nor burn persistantly or vigorously.  If  any
free liquid is present in the sample, the liquid must pass the test proce-
dure outlined in ASTM Standard D-93-79 or D-3278-78.  The waste  is classified
                                    62

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as hazardous if it has a flash point  less  than  60°C.   If  gases  are evolved
from the treated waste, they shall not be  ignitable as  determined  by
49 CFR 173.300.

     Example:  If a waste hydrocarbon is to be  blended  into  a cement mix,
ignitability tests should be run on any liquid  or  supension  associated with
the treated wastes.  Solid samples of the  treated  waste should  be  tested to
determine if a sustained fire is possible  when  the wastes are ignited.   The
Pensky-Martens Closed Cup Tester (ASTM D-93-79)  is particularly suited to
working with suspensions of solids and materials that  form fumes when heated.
Sustained burning of treated solid material can be judged using results from
tests such as ASTM F 501.  Data from  ASTM  F 501 should  include  flame time,
glow time, drip flaming time, and burn length.

6.1.2  Determination of Corrosivity.

     Any liquid associated with treated wastes  must have  a pH equal to or
greater than pH 2 and equal to or less than pH  12.5  (6-2,  6-3).  Treated
materials must not corrode steel (SAE 1020) at  a rate  greater than 6.35 mm
(0.250 in.)/yr at a test temperature  of 55°C  (130°F) as determined by the
National Association of Corrosion Engineers Standard TM-01-69 (6-3).

     Most cement or pozzolan-based treatment  systems will maintain a pH near
12.5 in any associated liquid due to  the calcium hydroxide present in the
additives.  The pH of a saturated aqueous  solution of  calcium hydroxide at
25°C is 12.4.  Therefore it would be  possible for  any  liquid associated with
treated material to fail this corrosivity  test.  The pozzolan or cement-
based treated material might only be  acceptable under  the corrosivity stan-
dard if no free liquid is present.

6.1.3  Determination of Reactivity.

     To be classified as non-hazardous the treated waste  should be normally
stable and not undergo violent chemical changes.   Materials  that react with
water will obviously have reacted during processing using cement or pozzolan
incorporation.  Compounds that are normally reactive will be diluted;  but  in
general will remain reactive.  Under  the alkaline  conditions involved in
cement incorporation, sulfides and cyanides will not normally decompose, but
if later exposed to acid groundwater, hydrogen  sulfide  or hydrogen cyanide
gas can be produced.  Both of these materials would be  inappropriate for
pozzolan or cement incorporation.  Solutions  with  high  concentrations of
ammonium compounds can decompose to produce ammonia gas in a strongly alka-
line environment.  These materials may present  problem  during processing and
disposal of treated wastes.

     Materials that are explosive, oxidizers  or autopolymerizable  substances
should also be disallowed in treated  wastes.  The  Explosive  Temperature Test
(40 CFR 250.13) could appropriately be applied  to  treated wastes where ex-
plosive potential is suspected.  Treated wastes  that contain materials  un-
stable to mechanical shock will, although  diluted, can  retain their insta-
bility in the blended product.  Bureau of  Explosives impact  testing
                                      63

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(49 CFR 173.53(b), (c), (d), and  (f)) could be appropriately used  for  testing
treated wastes.

6.1.4  Determination of EP Toxicity

     The standard EPA Extraction  Procedure  (EP) and maximum acceptable con-
taminate levels are outlined in reference 6-1.  The list of contaminants  rep-
resents only the minimum requirement at this  time and  therefore  does not
include many other potentially dangerous materials that might be present  in
the incorporated wastes.  The analytical requirements  should be  selected  to
suit the specific wastes blended  into the treated solid.  For example,
electroplating wastes commonly contain degreasing compounds and  phenolics.
It would be appropriate to look for these materials in the extracts from  any
treated electroplating sludge.

     The extraction procedure is  not efficient in assessing the  loss of
every contaminant.  Organic contaminants may  not be efficiently  extracted
from all matrices.  Where serious organic contamination is suspected,  addi-
tional testing using a variety of leaching  solutions would be prudent.

6.2  STEP 2.  DETERMINATION OF MAXIMUM TOXIC  HAZARD UNDER NORMAL CONDITIONS

     Because the solidified waste is to be  landfilled, it will be  exposed to
rainwater, soil water or possibly even groundwater  (assuming the water table
could rise into the landfill).  The surrounding water  could become saturated
with respect to any toxic or noxious compounds present as the wastes.

     In order to discover if the  waste can  release objectionable levels of
toxic substances, a maximum possible concentration  (MPC) type of test  can be
performed.  The solid sample is dried and ground to a  powder ( 200 mesh).
The ground sample is shaken or stirred in smallest practical volume of dis-
tilled water (at 20°-25°C) until  the concentration of  potentially  toxic con-
stituents no longer increases in  the solution in contact with the  waste.   If
it is suspected that a very soluble toxic material is  present in the ground
waste; the solution should be removed and placed in contact with a fresh
(unleached) aliquot of ground waste.  The goal of this type of test is to
determine as nearly as possible what concentration of  toxicants  can be
expected in water saturated with  respect to the compounds in the waste.

     An example of an effective MPC test protocol used in Harwell  Labora-
tories (U. K.) is given in reference (6-4).   The Harwell testing procedure is
a multiple shake test that uses a minimum amount of leachate to  assure that
a saturated condition is produced in the liquid.  Such tests represent a
worst-case situation.  Materials  that can show very low concentration  of
potential pollutants would rank well in selection of  treated materials for
disposal.

6.3  STEP 3.  DETERMINATION OF PHYSICAL INTEGRITY AND  DURABILITY

     In many stabilized/solidified wastes the containment properties depend
on limiting the surface area across which transfer  of  potential  pollutants


                                      64

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can occur.  Physical testing systems are  required  to  judge  the  durability of
the solidified waste.

     Physical testing of waste materials  becomes very important where the
conditions for shallow land burial are not  ideal.   For example,  durability
testing is important where cover will not be  sufficient to  prevent  cyclic
wetting and drying, or freezing and thawing.   If the  cover  is permeable,  all
of the containment for the waste may depend on the production of an imper-
meable monolith.  However, for treated materials that can be ground to a
powder and still not lose materials to leaching as in the MPC testing, the
durability tests would be important only  for  structural integrity and would
have little meaning for containment characteristics.

     Physical properties testing is covered in Section 3.   In general the
stronger, more impermeable, and durable a treated  waste, the more effective
will be its containment.  If the material does not fragment to  create dust
or increase the surface area for exchange,  losses  will be minimized.   Cement-
based treated wastes can be prepared with properties  that approach  com-
mercial concrete.  Tests have shown compressive strengths up to 2500 Ibs/ sq
in., with excellent durability, permeabilities of  7.9 x 10   cm/sec and less
than 20 % weight loss after 12 freeze-thaw  cycles  (6-4).  Column leach test-
ing has shown that in cement-based systems  the strongest material,  has the
minimum contaminant loss  (6-6).

     Where the maximum possible concentration tests show potentially hazard-
ous levels of toxicants, durability would have to  be  very high  to demon-
strate that physical characteristics of the material  will prevent this
"worst case" situation from occurring.

6.4  STEP 4.  ESTIMATION OF LEACHING LOSS OVER A LONG TERM

     Stabilized/solidified waste is meant to  be landfilled  and  to remain
buried indefinitely.  In cases where infiltration  is  minimal and dilution of
any potential leachate occur, no contamination from the waste will  be
detectable.

     When solidified wastes are buried the  major factor limiting the loss of
material from the monolithic mass is diffusion of  the chemical  constituents
to the surface of the solid.  The rate of solution of material  at the sur-
face is large compared to the diffusion rate.   Diffusion in a solid can be
assessed using tests such as the Uniform  Leaching  Procedure (ULP) given in
Appendix B.  The results of the ULP are given as effective  diffusivities
(measured in cm /sec).

     Effective diffusivities or leachability  constants can  be used  in com-
paring the containment afforded by different  solidification systems and for
predicting the long-term losses from masses of wastes (6-7).  Very  little
information is available on effective diffusities  of  solidified industrial
wastes.  Johnson and Lancione (6-8) presented some data on  diffusivities  of
stabilized/solidified arsenic wastes; but the testing protocol  used varied
significantly from the standard system.   Most data on leachabilities  of
                                     65

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solidified waste come from nuclear waste treatment.  Usually  the  elements
and the types of material treated differ greatly from typical  industrial
wastes.  In general, glass-fused wastes have had lower  loss rates then
plastic (bitumen) encapsulated materials and plastic (bitumen) materials
have lower loss rates than cement-based materials  (6-9).  Determining ef-
fective diffusinities is the best documented system for comparing the reten-
tion of different constituents of waste using  the  same  solidification system
as for comparing the containment produced by different  solidification sys-
tems on one waste.

     Diffusivities for different constituents  can  also  be used to model  the
long-term loss of specific materials from solidified waste materials that
have known shapes and dimensions.  Details of  modeling  are given  by Anders,
Bartel, and Altschuler (6-7).  If the size and shape of a waste mass are
known and if it can be assumed that diffusion  into a very dilute  solution  is
the principal transport mechanism, a model for the loss of individual con-
stituents can be set up.  Figures 6-1 and 6-2  give the  calculated retention
rates for cylindrical  barrel-size ingots  and for flat slabs  (10 cm thick)
for 100 years for materials having diffusinities ranging from 1 x 10    to
1 x 10~  .

     For example, if a cement-solidified cadmium waste  were being evaluated,
results from the ULP can be used to select an  appropriate curve.   If the
wastes are solidified in drums, the appropriate diffusivity curve from  Fig-
ure 6-1 would be selected and the percent loss of  cadmium from a  single
ingot could be estimated.  A steel drum would  normally  last 15 years so
solution losses could be estimated from a point 15 years from the time  of
burial when the solidified waste would be exposed. Similarly Figure 6-2
could be used to predict waste losses from a semi-infinite slab of waste
10 cm thick.  Other waste configurations can be modeled from  equations
available for less common shapes such as spheres or parallelepeds, etc.
(6-7).

6.5  STEP 5.  ASSESSMENT OF LAND BURIAL SITES

     Other manuals in this series have examined performance of land burial
sites and should be consulted  (6-10, 6-11).  In the case of treated wastes
where designs call for creating low permeability monoliths, the escape  of
potential contaminants has been assumed to occur principally  along the  sur-
face of the emplaced mass.  If the physical properties  of the waste  indicate
a durable final material, a maximum escape rate for contaminants  based  on
the surface area of the emplaced waste mass can be estimated.   This would  be
a maximum rate that would assume a maximum diffusion gradient (6-7).   Other
procedures such as estimation of percolation rate  from  cover  parameters and
examination of liner and drain performance would precede as with  landfills
designed to receive untreated wastes.

6.6  STEP 6.  EVALUATION OF MONITORING AND CLOSURE PROGRAMS

     Monitoring and closure of a solidified hazardous waste site  would  be
similar to any other hazardous waste facility. Manuals for assessing  these
                                      66

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            BARREL SIZED INGOT
            (90cm XSScm)
10   20   30
90    100
                             40    50   60   70
                                 YEARS
Figure 6-1.   Percent  of  constituents remaining in barrel-sized,
             cylindrical ingots  (90 cm long x 55 cm diam) of solidi-
             fied  waste  over  100  years of leaching for wastes
             having diffusivities of 10~  to 10~   cm /sec
                    67

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100
                          SLAB SIZE
                          10 em THICK
                            40   5©   60

                                YEARS
Figure 6-2.   Percent  of  constituent remaining in a sami-infinite
             slab  (10 cm thick) of solidified waste over 100 ye^rs
             of  leaching^for wastes having diffusitities of 10
             to  10    cm /sec.
                                                              100
                                                            ~
                              68

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aspects of landfill design should be consulted.   If  the  treated  wastes  were
classified as non-hazardous by EPA, then closure  of  the  facility would  be  no
different than any other waste disposal area.

6.7  STEP 7.  QUALITY CONTROL OF WASTE TREATMENT

     Treated waste material may vary greatly  from batch  to  batch due  to
variation in wastes incorporated or the conditions of  treatment.   In  cement
or pozzolan-based systems, small amounts of interfering  materials can reduce
strength, durability and chemical containment drastically.   In some solidi-
fication operations in which the material  is  poured  out  to  solidify as  a
monolithic mass, solidification may not occur and if an  additional layer is
poured over the unsuccessfully solidified  wastes, a  highly  leachable  zone  in
the waste mass is created.  Such poor operating practices should be avoided.

     Any treatment process should include  a system for determining the  char-
acter of the treated waste and a provision for reprocessing the  material
before final deposition if the treatment process  was unsuccessful.  The
exact sampling pattern for determining treatment  quality would depend on the
variability of the feedstock for the treatment system  and the quantity  of
waste treated.  In batch operations, each  separate batch should  be leach
tested and tested to determine selected physical  properties.  In a cement-
or pozzolan-based system, any large changes in set-time  or  texture of the
treated waste should be cause for a more complete testing sequence.   Sam-
pling procedures are outlined in references on industrial sampling designs
(6.12).

6.8  STEP 8.  EVALUATION OF AGED MATERIAL

     Periodically samples should be cored  from aged  solidifed wastes  to
determine if breakdown and loss of contaminants has  occurred.  If the physi-
cal properties, strength and durability have  not  decreased  and the perme-
ability of core materials has remained low, the assumption  of a  low-
permeability monolith of waste is justified.  Leach  testing of core material
can be used to ascertain any decrease in containment properties  with  age.
If a landfill operation can demonstrate that  the  treated waste is not break-
ing down, longer periods can be permitted  between resampling of  treated
waste.  For example in the first year of operation one core per  1000  cubic
meters volume might be judged adequate.  If the sample appears uniform  and
unchanged the core requirement could be halved.

6.9  PERMITTING AND OPERATING EXPERIENCE

     There are at present few long-term records for  operating hazardous
waste landfills where treatment is being employed.   Only small amounts  of
treated wastes have been emplaced at various  manufacturing  localities in the
United States.  Where these sites have been investigated, no major contami-
nation of groundwater or sub-waste soil has occurred (6.13,  6.14).  The lack
of experience with treated wastes and the  potential  for  application of
treatment processes to inappropriate waste dictates  that caution be exer-
cised in granting permits.
                                     69

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                                 REFERENCES
 6.1.   U.  S.  Environmental Protection Agency.  Hazardous Waste Management
       System; Part III,  Identification and Listing of Hazardous Wastes.
       Federal Register 45(98):33083-33133.  May 19, 1980.

 6.2.   U.  S.  Environmental Protection Agency.  Test Methods for the Evalua-
       tion of Solid Waste, Physical/Chemical Methods.  SW-646.  Office of
       Water  and Waste Management, Washington, D.C., 1980.  584 pp.

 6.3.   U.  S.  Environmental Protection Agency.  Methods for Chemical
       Analysis of Water and Wastes.  EPA 600/4-79-020, Environmental Moni-
       toring and Support Laboratory, U. S. Environmental Protection Agency,
       Cincinnati, Ohio,  1979.  1970.  298 pp.

 6.4   Wilson, D. C., and S. Waring.  The Safe Landfilling of Hazardous
       Wastes.  Paper presented at 3rd Int. Industrial Waste Waters and
       Waste  Congress, IUPAC, Stockholm, Sweden, Feb,  1980.  14 pp.

 6.5.   Bartos, M. J., and M. R.  Palermo.  Physical and Engineering Proper-
       ties of Hazardous Industrial Wastes and Sludges.  EPA 600/2-77-139.
       U.  S.  Environmental Protection Agency, Cincinnati, Ohio, 1977.  89 pp.

 6.6.   Jones, L. W., and P. G. Malone.  Physical Properties and Leach Testing
       of  Solidified/Stabilized Flue Gas Cleaning Wastes.  U. S. Environ-
       mental Protection Agency, Cincinnati, Ohio.   (in preparation).

 6.7.   Anders, 0. U., J.  F. Bartel, and S. J. Altschuler.  Determination of
       Leachability of Solids.  Analytical Chemistry.  50(4):564-569.   1978.

 6.8.   Johnson, J. C., and R. L. Lancione.  Assessment of Processes to
       Stabilize Arsenic-Laden Wastes,  pp. 181-186.   In:  Disposal of
       Hazardous Wastes.   EPA-600/9-8-010.  Environmental Protection Agency,
       Cincinnati, Ohio, 1980.

 6.9.   Moore, J. G., H. W. Godbee, and A. H. Kilbey.   1977.  Leach Behavior
       of  Hydrofracture Grout Incorporating Radioactive Wastes.  Nuclear
       Technology 32:39-52.   1977.

6.10.   Moore, C. H.  Landfill and Surface Impoundment  Performance Evaluation
       Manual.  U. S. Environmental Protection Agency, Cincinnati, Ohio.
       (in press).
                                     70

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6.11.  Perrier, E., and A. C. Gibson.  Hydrologic Simulation on Solid Waste
       Disposal Sites.  U. S. Environmental Protection Agency, Cincinnati,
       Ohio.  (in press).

6.12.  U. S. Environmental Protection Agency.  Samplers and Sampling Pro-
       cedures for Hazardous Waste Streams.  EPA/600/2-80-018.  U. S. En-
       vironmental Protection Agency, Cincinnati, Ohio, 1980.

6.13.  Mercer, R. B., P. G. Malone, and J. D. Broughton.  Field Evaluation
       of Chemically Stabilized Sludges,  pp 357-365.  In Shultz, D. W.
       (ed.).  Land Disposal of Hazardous Wastes.  EPA 600/9-78-016.  U. S.
       Environmental Protection Agency, Cincinnati, Ohio, 1978.   453 pp.

6.14.  Jones, L.  W.,  P. G. Malone, and T. E. Myers.  Field Investigation of
       Contaminant Loss from Chemically Stabilized Sludges.  Presented at
       Sixth Annual EPA Solid and Hazardous Waste Research Symposium,
       Chicago, Illinois,  March 17-20, 1980.  15 pp.
                                     71

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                                 APPENDIX A

                       SOURCES OF FIXATION TECHNOLOGY
     The data in this appendix were obtained from:  Environmental Labora-
tory, U. S. Army Waterways Experiment Station.  Survey of Solidification/
Stabilization Technology for Hazardous Industrial Wastes.   (EPA-600/2-79-056,
U. S. Environmental Protection Agency, Cincinnati, OH.   1979.)  Addition and
changes contained in this appendix are from new communications  from vendors.

NOTE:  All information given in Appendix A has been taken directly from
vendor literature and sales brochures.  No attempt has been made to verify
or interpret any vendor claims.  This listing is given for  illustrative and
informational purposes only and should not be used for design or permit
functions.
                                      72

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a.  Name of Vendor:  Atcor Washington Inc.
                     Division of Chem Nuclear Systems, Inc.
                     Park Mall
                     Peekskill, NY  10566

    Contact:  M. Brownstein, Director
              (914) 739-9000

b.  Category of fixing process:  The process is classed as a masonry-based
solidification systems (using cement).

c.  Types of wastes treated:  System is primarily designed to effectively
solidify typical wastes from both boiling water reactor and pressurized water
reactor nuclear power plants (which include 25% Na^SO,, 12% H^BOo, bead type
ion exchange resin and various filter media - solka floe, diatomeccous earth
and filter aid).  The Atcor Radwaste Solidification System includes an
in-line mixer/feeder which fills any size container, permits inclusion of
bulky items and flushes clean with a minimum of water.  All operation
procedures are remote and/or automatic.

d.  Types of waste excluded from treatment:  sludges which do not combine
with cement could not be handled, however, testing for specific sludges is
required to ensure application suitability.

e.  Cost of fixation:  Cost is variable depending upon waste to be treated.
Dry masonry cement is added up to volume equal to the volume of waste which
gives final product about 130% of volume of original waste.  Cement cost is
approximately 9 cents per kilogram, but capital expenditure, transportation
and personnel costs will vary greatly with the individual job.

f.  Leach and strength tests:  Leach and strength studies showing product
acceptability for cement-based radwaste systems are numerous.  The product
is a monolithic cement structure exhibiting no free water and an acceptable
leach rate for shallow-land burial.

g.  Examples of past applications and current contracts:  At present the
Atcor system is used solely within the commercial nuclear power industry,
however, studies are currently under way to use system for solidifying
arsenic wastes and incinerator-generated wastes.  Radwaste solidification
systems have been purchased by 11 major power companies including:  Northern
States Power Company (Monticello and Prairie Island), Wisconsin Public
Service Co. (Kewanee), Wisconsin Electric and Power Co. (Point Beach), Ten-
nessee Valley Authority (Beliefonte), Taiwan Power Co. (Chin-Shan and
Kwosheny), Duquesne Light Co. (Beaver Valley), and others.
                                     73

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a.  Name of Vendor:  Canadian Waste Technology, Inc.
                     160 Torbay Road
                     Markham, Ontario  L3R-1G6
                     Canada
    Contact:  David Krofchak, President, Canadian Waste Technology, Inc.
              (416) 495-9502

b.  Category of fixing process:  The solidification process is based upon
the production of stable silicate compounds analogous to natural geologic
materials.

c.  Type of waste treated:  All inorganic wastes from heavy, medium and  light
industries such as waste pickle liquor, plating wastes, etc., containing
acids, chromium, copper, iron, magnesium, manganese, nickel, zinc, cadmium,
lead, mercury, vanadium, chlordies, sulphates, phosphorous and virtually any
inorganic chemical or combination thereof.  Specialized applications have
been designed to treat mine tailing wastes and sewage sludges from primary
and secondary treatment plants.

d.  Types of waste excluded from treatment:  The process is ineffective
against some organic wastes, but organic wastes of up to 20% of the volume
of the formulated inorganic wastes have been treated successfully on a case
to case basis.

e.  Approximate cost of processing:  Each location where wastes are treated
has different costs depending upon quantity of wastes and the method of
operation.  However, costs of approximately $8.00 per cubic meter ($6.00 per
cubic yard) or 0.8 cents per liter (3 cents per gallon) are easily achieved
(August 1977),  This price assumes no cost for removal of solidified material
from the site.  No apparent increase in fixed material to raw sludge volume
has been found.

f.  Data on leach and strength tests:  Extensive strength and leach tests
have been made by the company; those cited below were in cooperation with
the Ontario, Canada, Ministry of the Environment, Pollution Control Branch,
Industrial Section (from a paper entitled "An Assessment of a Process for
the Solidification and Stabilization of Liquid Industrial Wastes, 1976,  by
G. A. Kerr, Q.C., Minister) the conclusions of this report were:

    (1)  The solidification process appeared to hold and stabilize most  of
the heavy metals contained in the liquid  (acidic metal-bearing liquid indus-
trial wastes).  Heavy metal values in the leachates (laboratory and field)
were commonly below 1 mg/liter.

    (2)  Leachates from the testing of processed material contained high
concentrations of dissolved solids.

    (3)  The bulk of the common heavy metals present in the waste were re-
tained in the processed material during extended period of leaching with
distilled water when considered on a mass basis.  Losses of heavy metals
were relatively minor.
                                      74

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    (4)  Landfilling may be used to dispose of  the processed material  pro-
viding adequate facilities are available for the collection and  treatment  of
leachate and run-off.  The concern over dissolved solids  contamination will
dictate the adequacy of the facilities required.
                                      /•    o
         Material with up to 20.7 x 10  N/m  (3000 psi) unconfined  compres-
sive strength has been produced, but for reasons of cost,  the  end product  is
generally of low strength.

g.  Examples of past applications and current contracts:   Currently over
380,000 liters/day (100,000 gpd) are being treated at a treatment site in
the city of Hamilton, Ontario.  The fixed material is being used as a  cover
for the sanitary landfill.  Negotiations are currently underway  with com-
panies in the United States and in Canada for the licensing of the  technology
to operate similar sites and many cases to treat company  wastes  on  site.
                                      75

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a.  Name of Vendor:  Chemfix, Inc.
                     1675 Airline Highway
                     Kenner, Louisiana  70062
               or mail correspondence to:
                     P. 0. Box 1572
                     Kenner, Louisiana  70063

     Contact:  M. W. Duncan, President
              (504)729-4561

b.  Category of fixing process:  Inorganic chemical additives  (cements  and
soluble silicates) are mixed with the wastes to produce a gelling reaction
that is followed by hardening.  Mobile treatment plants that can each handle
1,000,000 liters/10 hour shift are provided.  The process is also applied in
fixed installations.  The additives consist of less than 5% up  to 10% by
volume of the waste.  The process varies with the percent solids and nature
of the wastes.  Generally the higher the percent solids the lower the
additive requirement.

c.  Types of wastes treated:  Most types of waste can be accepted for this
processing.  The additives react with polyvalent metal ions producing stable,
insoluble, inorganic compounds.  Nonreactive materials (e.g. certain
organics and asbestos) are physically entrapped in the matrix  structure
resulting from the reaction process.  Process is usually custom designed
for each type of waste.

d.  Types of waste excluded from treatment:  Some wastes containing certain
organic compounds and/or toxic anions are not normally treated, however, in
some such cases, specified pretreatment will allow solidification/fixation.

e.  Approximate cost of processing:  Varies greatly with the % solids and
nature of the waste.  Laboratory testing to determine cost is  provided.
Reagent costs would typically fall in 1 to 5
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a.  Name of Vendor:  Dravo Lime Company
                     650 Smithfield Street
                     Pittsburgh, PA  15222

    Contact:  C. J. McCormick
              (412) 566-4433

b.  Category of fixing process:  Dravo Lime Company's solidification  addi-
tive, Calcilox, is a dry, free flowing, light grey-colored powder of  inor-
ganic origin.  It is hydraulically active and when added  to  the  slurry
improves its handling and ultimate land disposal characteristics by imparting
structural integrity to the settled slurry.  The process  could probably  best
be classed as pozzolanic or cementitious.

c.  Type of waste treated:  Calcilox is applicable to all calcium-based  SO
scrubber waste as typically produced from coal-fired utility  scrubbers.
Calcilox is also applied to many inorganic mineral processing tailings that
contain a large percentage of silica and alumina.  Typical applications  are
on fine coal preparation wastes and uranium mill tailings.

d.  Type of waste excluded from treatment:  Sludges containing organics  and
sewage wastes cannot be treated.

e.  Approximate cost of processing:  The weight percent of Calcilox additive
dosage ranges from 5 to 15% of the dry slurry solids weight.  Low dosages
(5-10%) are used with mechanically dewatered wastes (55 to 70% solids) and
higher dosages (10-15%) with lower solids slurries such as thickener  under-
flows with 25 to 35% solids.  Costs are site and process  dependent:   no  firm
estimates are available.

f.  Data on leach and strength tests:  Leach data are available  from  field
tests on flue gas cleaning waste and indicate reduced leach  rates when com-
pared to raw sludges.  Typically, leaching rates are reduced  one to two
orders of magnitude below untreated wastes.  The strength of  the product is
controlled by the mixing ratios, but the product has a dry,  clay-like con-
sistency similar to compacted clayish soil.

g.  Examples of past application and current contracts:   Extensive experience
has been gained through contracts with several large power plants such as
the Bruce Mansfield Power Station in Shippingport, PA, the Duquesne Light
Company Phillips Power Station, and Allegheny Power Service  Company's
Pleasants Station.  Current coal waste applications are at several large
American Electric Power Company mines and at smaller independent operations
in Ohio and West Virginia.  Ongoing tests are being conducted with several
uranium producers in the western United States under a Department of  Energy
contract.

"Calcilox" is a registered trademark of Dravo Lime Co.
                                      77

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a.  Name of Vendor:  Environmental Technology Corporation
                     Suite 200
                     1517 Woodruff Street
                     Pittsburgh, PA  15220

    Contact:  Albert R. Kupsiec, Vice President
              (412) 431-8586

b.  Category of fixing process:  The ETC Solidification System requires  com-
monly available reagents in addition to the lime which is currently used in
wastewater processes.  The hazardous wastes are neutralized and  solidified
resulting in a sludge which totally encapsulates the moisture and  chemically
binds heavy metals and other chemicals within the sludge.

    Lime is required to neutralize the acidity of the hazardous  waste  and to
complex most of the heavy metal cations as insoluble hydroxides.   Chemistry
of the reagents is well known, but before now they had not been  used in  a
single system.  One of the reagent acts as an ion exchange media for complete
heavy metal removal and removes excess water within the system.  The other
reagents act as binders which bridge the sludge particles and increases  the
physical strength and load-bearing capacity of the final sludge.   The  final
sludge produced is soil-like in appearance.

c.  Types of waste treated:  The hazardous wastes involved in the  development
of the ETC system are mostly spent pickling acids from steel mills.  Sulphu-
ric acid composes the largest amount of wastes by volume.  Other types of
wastes treated include (1) hydrochloric acids; (2) other pickling  acids;
(3) spent plating solutions; (4) sludge from industrial waste treatment
plants; (5) scrubber sludges; and  (6) organic sludges.

d.  Types of waste excluded from treatment:  None listed.

e.  Approximate cost of processing:  Cost of neutralizing and solidification
of waste pickle liquors varies with the method of mixing and type  of lime
used.  Treatment with dry lime followed by ETC reagents costs one  cent per
liter.  Addition of lime as a slurry increases the amount of the other re-
agents required so that the costs  rise.  Other sludges can be stabilized at
costs of 0.40 cents to 3.00 cents  per liter.

f.  Data on leach and strength tests:  Leach tests were conducted  in the open
in lined, V-shaped trenches fixed  with perforated plastic pipe which directed
all leached liquid into plastic collection buckets.  After about one month
the leachate from 10 different sludges had from 1000-5000 mg/1 total dis-
solved solids, 500-800 mg/1 SO^ and 150-600 mg/1 Cl.  Analysis for heavy
metals showed less than 0.01 mg/1  of nickel, zinc, iron, chromium  and  manga-
nese.  Only copper was present at  0.03-0.04 mg/1 levels. Hardness  (i.e.
physical strength) is a function of the total amount of solids present and
the quantity of reagents added.

g.  Examples of past applications  and current contracts:  None reported.
                                      78

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a.  Name of Vendor:  Envirotech
                     3000 Sand Hill Road
                     Menlo Park, CA  94205

    Contact:  David L. Keaton, Vice-President

    NOTE:  For information on treatment of S02 sludges contact:
           Walter Renburg, Jr.
           Air Group/Pittsburgh
           Envirotech Corporation
           Two Airport Office Park
           400 Rouser Road
           Pittsburgh, PA  15108

b.  Category of fixing process:  The process is sodium silicate and cement-
based.   (U. S. Patent 3,837,872)  Envirotech is the exclusive licensee  in
the field of fixed treatment units for National Environmental Control,  Inc.
(parent company of Chemfix Corporation).

c.  Types of waste treated:  Details available from company.

d.  Types of waste excluded from treatment:  Details available from company.

e.  Approximate costs of processing:  Figures available from company.

f.  Data on leach and strength tests:  Can be obtained from company.

g.  Examples of past applications and current contracts:  Contact company
directly.
                                     79

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a.   Name of Vendor:  Hittman Nuclear and Development Corporation
                      9190 Red Branch Road
                      Columbia, MD  21045

     Contact:  Charles W. Mallory
               Vice President, Engineering
               (301) 730-7800

b.   Category of fixing process:  Hittman Corp. uses a variety of volume
reduction and binding techniques to produce waste containment.  They have
experience with ion-exchange, carbon adsorption, evaporation, and incin-
eration with cement, gypsum and organic binders (such as Dow binder).
Selected chemical additives are used with binders to ensure waste retention.

c.   Types of wastes treated:  Hittman has had experience with radioactive
waste including aqueous solutions, sludges, filter media, oils, and organic
liquids.

d.   Type of waste excluded from treatment:  None encountered.

e.   Approximate cost of processing:  This is application dependent and must
be determined on a case-by-case basis.

f.   Leach and strength tests:  Representative data are available from the
vendor.

g.   Examples of past applications and current contracts:  Hittman Corp.
operates solidification/stabilization services for 15 to 20 nuclear power
plants across the United States.
                                     80

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a.  Name of Vendor:  I. U. Conversion Systems, Inc.
                     115 Gibraltar Road
                     Horsham, PA  19044

    Contact:  Norman F. O'Leary, Vice President, Marketing; or
              Richard W. Patton, Industrial Sales Manager
              (215) 441-5920

b.  Category of fixing process.  The IUCS Poz-0- Tec process utilizes  fly  ash
and other additives.  The Poz-0-Tec chemistry is a combination of  two simul-
taneous reactions:  a rapid reaction that occurs between the  soluble  salts
present in fly ash and the lime and alumina that is found in  the fly  ash
glass; and a slower pozzolanic reaction that occurs between the silica  in
the fly ash and lime. The latter reaction occurs over a period of  months.

c.  Types of waste treated:  This solidification system was developed ini-
tially for the electric utility industry for SO- scrubber sludge stabiliza-
tion.  Four million tons of FGC sludge is treated by this process  in  a  single
year.

    Conversion Systems has also successfully stabilized and tested electro-
plating wastes, steel mill wastes, and chemical process wastes.  Based  upon
these results, the process can stabilize or encapsulate wastes having the
potential of leaching salts or heavy metals into the environment.

d.  Wastes not suitable for treatment:  Some organic wastes.

e.  Approximate cost of fixation:  Each waste must be evaluated for each
client by Conversion Systems.  Several alternative methods are available
which result in somewhat different scopes of service.  Preliminary cost es-
timates for processing sludges usually fall in the range of 1 to 7 cents  per
liter of waste. Some parameters influencing this range are quantity to  be
processed, water content, waste toxicity, equipment redundancy, desired
methods of operation and scheduling requirements.

f.  Leach and strength tests:  Physical and environmental properties  of Poz-
0-Tec improve with time as the pozzolanic reactions proceed.  The  cementi-
tious reaction produces a monolithic mass of low permeability which is
subject to surface leaching only.  The following is a compilation  of  typical
structural properties of Poz-0-Tec stabilized material:

    Wet density               1360-1600 kg/nu (85-100 Ib/cu ft)
    Dry density               1040-1360 kg/m  (6585 Ib/cu ft)
    Moisture content          2550% moisture,.,
    Cohesion                  >95.7 x 10 N/m  (>2000 Ib/sq ft)
    Unconfined compressive
     strength                 >!.  x lO^N/m  (>25 Ib/sq ft)
    Permeability coefficient  10   to 10~  cm/sec
    Allowable bearing
     capacity                 2.87 x 10 N/m   (3 tons/sq  ft)
    Stable fill slope         2 horizontal to 1 vertical
    Saturation                incomplete

                                      81

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    Poz-0-Tec stabilized sludge may occupy more volume than the unstabilized
sludge, but any increase in material is offset by the weight reduction
brought about by dewatering the sludge before treatment and the greater
heights to which the fixed sludge pile can be built in the disposal area.

g.  Examples of past applications and current contracts:  Conversion  systems
currently has contracted to fix 8 million metric tons of SO  scrubber sludge
produced at eleven electric power plants in the U. S.  It is also stabilizing
all wastes from an SO  scrubber and water treatment plant of a large  battery
manufacturer.

    The company is also developing alternative disposal applications  where
the physical characteristics of the fixed sludge can be used to advantage.
Poz-0-Tec stabilized materials have been used as a base in parking  lot and
road beds.  Cast Poz-0-Tec blocks are currently under study for use in con-
structing artificial reefs.

    Poz-0-Tec is a registered trademark of I. U. Conversion Systems,  Inc.
                                      82

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a.  Name of Vendor:  Industrial Waste Management, Inc.
                     Suite 70, 340 E. 64th Street
                     New York, New York  10021

    Contact:  B. Alva Schoomer, President
              (212) 355-1979

b.  Category of fixing process:  The Enviroclean process may utilize portland
cements or lime and pozzolans or cement and lime and pozzolans depending upon
desired results and local availability in some instances.  Processed waste  is
soil-like in consistency and becomes concrete-like mass.  Strength continues
to develop over period of years.  U.S. patent pending on process.  Company
emphasis is on recycling of wastes by processing right on site into roadways,
parking lots and walkways.

c.  Types waste treated:  Industrial, utility and certain municipal wastes.

d.  Wastes not suitable for treatment:  Most organics and wastes of less than
15% solids for reasons of economics.

e.  Approximate cost of fixation:  $12/yd3 to $20/yd3 ($15.60 to $26.20/m3)
not including removal, hauling or final disposal.  Cost will vary with  in-
dividual sludge chemical composition, water content and volume to be
processed.

f.  Leach and strength tests:  Both leach test results and strength develop-
ment as well as permeability will vary by the chemical addition rate and the
type of sludge. ^Initial strengths in the 15 to 40 Ibs/ft  range develop^
75 to 400 Ibs/ft  range in 3 to 6 months typically and 300 to 700 Ibs/ft
in two years.- Permeabilities initially in the 10   to 10   cm/sec range will
reduce to 10   to 10   within one month.  A 48 hr. leachate test with dis-
tilled water from a toxic metal hydroxide sludge from an etching operation
report ion concentrations below 0.5 ppm for Cu, Fe, Pb, Zn, Cr (total), PO  ,
Ni and Cd.

    Volume increase from addition of materials for chemical stabilization
will vary from 1.1 to 1.6 times pretreatment volume.

g.  Examples of past application and current contracts:  Company is currently
entering U.S. market.  Past applications available directly from company.
Enviroclean is a pending service mark of Industrial Waste Management, Inc.
                                      83

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a.  Name of Vendor:  Newport News Industrial Corp.
                     230 41st Street
                     Newport News, VA   23607

    Contact:  J. R. May, Manager, Radwaste Management Systems
              (804) 380-7761

Newport News Industrial Corporation is primarily involved with volume
reduction and waste handling techniques for radioactive materials.  They
have broad experience with producing compact wastes that are compatible with
solidifying agents such as urea-formaldehyde, water extendable polyesters
and bitumen.  They are currently in the process of developing a new solidifi-
cation method applicable to hazardous chemical wastes including radwastes.

b.  Category of fixing process:  Not available.

c.  Type of waste treated:  Not available.

d.  Type of waste excluded from treatment:  Not available.

e.  Approximate cost of processing:  Not available.

f.  Data on leach and strength tests:  Not available.

g.  Examples of past application and current contacts:  Process still  in
developmental stage.
                                      84

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a.  Name of Vendor:  Polymeric Materials Section
                     Department of Materials Science and Engineering
                     Washington State University
                     Pullman, WA  99164

    Contact:  R. V. Subramanian
              (509) 335-6784

    NOTE:  The Department of Materials Science and Engineering,  Polymeric
Materials Section is not a vendor of the raw materials and  equipment  neces-
sary for fixation, but has extensive experience and developmental  expertise
in the polyester encapsulation of hazardous wastes.  In cooperation with
members of the Department of Chemical Engineering, this technology has  suc-
cessfully been developed through the pilot plant stage.

b.  Category of fixing process:  An organic polymer (polyester resin) is used
to solidify the wastes.

c.  Types of waste treated:  Although very broadly effective, the  process
appears to be quite effective for low-level radioactive wastes,  metal ion
wastes, cyanides, arsenic wastes, and some specific organic wastes such as
kepone, PCB, and some pharmaceuticals.

d.  Type of waste excluded from treatment:  The process is  not effective on
very highly acidic sludges (especially at pH less than 1.0).

e.  Approximate cost of processing:  The price of polyester resin  is  about
$1.00/kg (45 cents/lb).  Since the maximum volume fraction  of close-packed
spheres is 74%, the minimum amount of resin which must be added  to the  waste
is about 25% by volume.  The fixed waste is usually 133% to 175% of the vol-
ume of the unfixed waste.

f.  Data on leach and strength tests:  Tests made using a fixed  product
encapsulating 60% by weight of,a 24% sodium sulfate solution indicated  com-
pressive strength of 15.0 x 10  N/m  (2180 psi).  Irradiation with 600  Mgad
gamma radiation actually increased the compressive strength to 20.7 x 10
N/m  (3000 psi).  The strength of the product is dependent  upon  the type,
proportion and form of waste incorporated.

    The leachabilities of Co-58, Sr^85 and Cs-134 from a similar encapsulated
sodium sulfate waste were 3.2 x 10  , 3.5 x 10  , and 5.9 x 10   cm,  respec-
tively over a period of 120 days.  The leach curves leveled off  at this value
after an initial rise in the first 20 days.  Thus, the leachability,  after
the initial dissolution of surface material, was practically negligible.

g.  Examples of past applications and current contracts:  Ontario  Hydro,
Toronto, Ontario is pursuing this process for rad waste encapsulation.
                                      85

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a.  Name of Vendor:  Sandia Laboratories
                     Albuquerque, NM  87115

    Contact:  R. L. Schwoebel, Manager
              Chemistry and Materials Characterization Department
              (505) 264-4309, ext. 5820

    NOTE:  Sandia's waste management program is wholly oriented toward  sta-
bilization of radiation containing wastes (July 1975).

b.  Category of fixing process:  The Sandia Solidification Process project
is a feasibility study of the solidification of solid wastes.  Fission  prod-
ucts cations and actinides undergo ion exchange on inorganic ion exchangers
being developed at Sandia Laboratories.  These ion exchangers are hydrous
oxides of Ti, Zr, Nb, Ta.

c.  Type of waste treated:  The process is designed for high-level radio-
active wastes such as the high level waste stream resulting from commercial
nuclear fuel reprocessing was well as caustic defense waste streams with high
salt (NaNO ) contents.

d.  Type of waste excluded from treatment:  The high  cost of process pre-
cludes low value, low hazard wastes.

e.  Approximate cost of processing:  Cost estimates for continuous column
flow systems are comparable to glassification processes.  Periodic batch
processing would probably be cheaper than glassification.

f.  Data on leach and strength tests:  The final product, subsequent to ion
exchange, could be fired to produce a ceramic product  (mixed titanates  and
titania) having leach rates as much as an order of magnitude lower than that
of borosilicate glass stabilized waste.

g.  Examples of past applications and current contracts:  Process in feasi-
bility study stage only.
                                      86

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a.  Name of Vendor:  Sludge Fixation Technology,  Inc.
                     227 Thorn Avenue
                     P. 0. Box 32
                     Orchard Park, NY   14127

    Contact:  Richard E. Valiga
              (716) 662-1005

b.  Category of fixing process:  The Terra Crete  process  is  a  "self-cementing
process" based on the production of a cementitious material  from  calcium
sulfite hemihydrate or calcium sulfate.  A portion of  the sulfite/sulfate
sludge stream is dried and calcined to produce a  cementitious  agent.   This
material and other additives (as needed) are introduced into the  waste stream
and react to form a hard, low permeability mass from the  sludge.

c.  Types of waste treated:  The system is primarily designed  to  operate with
sulfite/sulfate-based sludges produced from SO  stack  scrubbing operations
but is adaptable to other situations where calcium sulfite/sulfate  sludges
can be obtained.

d.  Types of wastes excluded from  treatment:  Not specified.

e.  Cost of fixation:  A flue gas  cleaning sludge would cost between  $2.00
-2.75 per ton for fixation.

f.  Leach and strength tests:  Data on leaching of antimony  and lead-rich
flue gas cleaning sludge shows  0.01 ppm lead in  the leach liquid.  The un-
confined compressive strength obtained from the Terra  Crete material  depends
on the amounts of additive used, but data showing strengths  from  9.57 x 10
N/m  (200 Ibs/ft ) to 5.74 x 10  a/m  (12,000 Ibs/ft ) are available.   Per-
meabilities are on the order of 10 " to 10   cm/sec.

g.  Examples of past applications and current contacts:  None  specified.

Terra Crete is a registered trademark of Sludge Fixation Technology,  Inc.
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a.  Name of Vendor:  Southwest Research Institute
                     8500 Culebra Road
                     P. 0. Drawer 28510
                     San Antonio, Texas  78284

    Contact:  John M. Dole, Manager
              Process Research & Engineering

    NOTE:  Southwest Research Institute (SRI) is a contract research organi-
zation and as such is not marketing processes or products.

b.  Category of fixation process:  Two fixation processes have been
developed:

    (1)  SRI has developed a thermoplastic epoxy system that combines  the
better features of thermosetting epoxy system with the better features of
thermoplastic systems.  Low-cost extended epoxy resins and hardeners which
are solids at ambient temperatures are heated (204°C) where they become  low
viscosity liquids.  They are then combined and mixed with heated fillers or
aggregates and discharged.  They set instantly as thermoplastic materials
and then cure as a thermosetting material to provide the typical physical
property features of epoxy containers.  These epoxy materials can be used as
coatings for other fixation processes.

    (2)  Three different systems using sulfur have been developed for  indus-
trial sludge stabilization.  These systems are:  (a) a modified sulfur
process where sulfur is used as a binder for the toxic sludge to produce a
concrete-like material. Since sulfur melts at about 120°C, the sludge must
be heated and dried before processing.  Because of the brittle nature  of
sulfur, a modified form is usually found to be superior for concrete applica-
tions; (b) the plasticized liquid sulfur system is a new development in  which
sulfur is modified to the extent that it can be used as a substitute for
asphalt;  (c) the third process is sulfur impregnation.  Surfur has been  used
previously as an impregnation agent for concrete, gypsum, porous brick,  tile
and mud block.  In addition to filling the voids to reduce water absorption,
considerable strength improvements also result.  This system is of use in
increasing the strength and leach resistance of sludge fixed by other  methods
such as concrete admixing.  Most of the sulfur composite work listed above
is still in the developmental stage.

c.  Types of wastes treated:  Not fully determined.

d.  Wastes not suitable for treatment:  Not fully determined.

e.  Approximate cost of fixation:  Not determined.

f.  Leach and strength tests:  Not yet available.

g.  Examples of past applications and current contracts:  Currently  in de-
velopment and testing phase.
                                       88

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a.  Name of Vendor:  Stabatrol Corporation
                     1402 Conshohocken Road
                     Norristown, PA   19401

    Contact:  Richard E. Valiga
              (215) 279-3992

b.  Category of fixing process:  The Terra Tite process involves  the addition
of cementitious materials to the waste sludge to produce a concrete-like
material.

c.  Types of waste treated:  Most industrial wastes can be treated.  The
Terra Tite process has great technical flexibility.

d.  Types of wastes excluded from treatment:  None specified.

e.  Cost of fixation:  None specified.

f.  Leach and strength tests:  Permeabilities on the order of  10   cm/sec
are obtained.  Leaching is insignificantly low.  Terra^Tite^material has
shown unconfined compressive strengths up to 4.78 x 10  N/m   (5 tons/sq ft).

g.  Examples of past applications and current contacts:  Heavy metal sludges,
50,000 tons; heavy metal salt cake, 10,000 tons; contaminated  soils,
5,000 tons.

Terra Tite is a trademark of Stabatrol Corporation.
                                     89

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a.  Name of Vendor:  Stablex Corporation
                     Suite 112
                     2 Radnor Corporation Center
                     Radnor, PA  19087

    Contact:  John Scofield
              (215) 688-3131

b.  Category of fixing process:  The patented  technology, described  as
Sealosafe, involves adding two silicate-based  powders to the waste which  is
dissolved or dispersed in water thereby producing a slurry and  the slurry
sets into a rigid, rock-like cast.  Due to its physical and chemical  form,
this mass is referred to as synthetic rock.

    The physical and chemical interactions which take place simultaneously
are referred to as the mechanism of crystal capture.  Up to ten additional
ingredients are also used, depending upon the  type of waste to  be treated,
to enable the crystal capture mechanism to operate under optimum conditions.

c.  Types of wastes treated:  The process is suitable for:

    (1)  All inorganic wastes.

    (2)  Organic wastes which can be homogenously incorporated  into  an
aqueous phase either by dissolution, suspension, or absorption.

    (3)  Wastes in (1) or  (2) above in liquid, solid, or sludge form, includ-
ing contaminated articles  such as filter cartridges, clothing,  rubber boots,
etc.

    (4)  The process is exceptionally successful in treating all heavy
metals, arsenic, mercury and asbestos.  The process also deals  with  anionic
wastes such as fluoride, chloride, etc.

d.  Wastes not suitable for treatment:  The process is not suitable  for
solidification of:

    (1)  Oils, solvents, and greases which are not miscible with an  aqueous
phase.

    (2)  Very large quantities of water with minimal amounts of toxic
ingredients.

e.  Approximate cost of fixation:  In typical  applications one  ton of waste
would yield 1.15 to 1.4 tons of end product, called Stablex.  The volume
increase  in this weight increase  is between 5% and  10%.

    Precise cost estimates are not possible because of  the different prop-
erties of the wastes to be treated.  Experience  indicates an extremely  broad
range of between $5.00 to  $350.00 per ton depending upon the type, quantity
and complexity of  the waste involved.


                                     90

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f.  Leach and strength tests:  Extensive experience and information  is
provided by the company.  The product, Stablex, is 10 times  less permeable
than concrete.  Leaching tests in which fixed samples are ground to  a fine
powder and totally immersed and wetted in ten-times their weight of  dis-
tilled water for one hour indicate that very little material  is lost to the
water. One example using a solid waste fixed by the process  and hardened  for
three days (and containing 39,000 ppm copper, 46,000 ppm zinc, and 42,000 ppm
chromium) lost less than one ppm of these toxicants.  The product, Stablex,
has an unconfined compressive strength about equal to that of  the grouts  used
for void filling and soil stabilization but much lower than  concretes and
mortars.

g.  Examples of past applications and current contracts:  A  treatment center
near Birmingham in the United Kingdom has a current throughput of 200,000
tons of waste per year (its capacity will be increased from  70,000 tons per
year in 1978).  Another treatment center near London, U.K., was commissioned
in 1978 with a capacity of 400,000 tons per year.  Both plants operate as
regional treatment plants handling a variety of wastes from  different
sources. Construction of two plants in Japan and the first plant in  the
U. S. has been scheduled to begin in 1979.

The Sealosafe Service includes a process protected by patents  and patent  ap-
plications in the United States and overseas and Sealosafe and Stablex are
trademarks of the Stablex Group of Companies.
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a.  Name of Vendor:  TJK, Inc.
                     7407 Fulton Avenue
                     North Hollywood, CA  91605

    Contact:  Masaaki Endo, General Manager
              (213) 875-0410

    NOTE:  This company has contracted to market the Takenaka Sludge Treat-
ment (TST) System  (Takenaka Komuten Co., Osaka, Japan) in the U. S.  Studies
conducted by EPA on Kepone and arsenic disposal problems are now underway.

b.  Category of fixing process:  Hardeners are principally cement-family  or
cement-based materials.  In addition, special additives are used for sta-
bilizing harmful substances.  Several series of hardeners are used depending
upon the specific mud or sludge to be treated.

c.  Type of waste  treated:  The TST system is a technique for solidifying
mud of comparatively high water content or sludge discharged from factories
and plants.  It transforms the material into a form easy to handle for  uti-
lization in land reclamation and pollutant control.  Treatable material can
be widely dispersed, settled sludge or sludge obtained directly from the
factory or plant.  In the case of sludges with toxic substances such as
mercury, chromium  and cadmium, TST treatment stabilizes and chemically  fixes
these harmful substances.

d.  Types of waste excluded from treatment:  Two types of sludges tested  but
found unsuitable are sludge produced from a wool scouring plant (greater  than
20% fats and oils) and sludges containing large amounts of paints wastes.

e.  Approximate cost of processing:  Costs of processing will, of course,
vary with the type of sludge and additives required but will run from about
$10/m   ($8/yd ) to $20/m   ($16/yd ).  These estimates do not include trans-
portation or disposal.  Volume increase upon treatment is from 1.05 to  1.15
times pretreatment volume.

f.  Data on leach  and strength tests:  Extensive leach testing has been
carried out by the company.  In their standard leach test, the treated  sludge
is ground to a particle size between 0.5 mm and 5 mm.  This powder is then
mixed with distilled water and adjusted to pH of between 5.8 and 6.3 with
HC1 or C02. The final mixture  (100 ml) is 10%  (weight/volume) sludge to
water.  This mixture is stirred for 6 hours at room temperature and 1 atmo-
sphere and then filtered or centrifuged before analysis.  Results of tests
made with a wide variety of sludges and muds containing a wide variety  of
toxic metal ions show that only low levels of pollutants are released even
in this relatively severe  leaching test.  (Ions reported and their maximum
allowable concentrations: Alkyl-Hg and Hg, no detectable; Cd, 0.3 mg/1; Pb,
3 mg/1; organic-P, 1 mg/1; Cr  , 1.5 mg/1; As, 1.5 mg/1 and CN, 1 mg/1.)

    Unconfined compressive strength varies widely with the type of sludge
and kind and amount of additives used, but values of 5-10 x 10  N/m  are  not
unusual with 20%  (w/v) additives.
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g.  Examples of past applications and current contracts:  Twenty-six projects
have been completed since 1973.  Seventeen projects involved deposits under
water (46,000 m ), seven involved factory discharges (14,500 m ) .  In the
majority of these projects toxic substances were successfully contained.
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a.  Name of Vendor:  Teledyne Energy Systems, Inc.
                     110 West Timonium Rd.
                     Timonium, MD  21093

    Contact:  William E. Osmeyer, Product Manager
              (301) 252-8220

b.  Category of fixing process:  The company sells cement, asphalt, and
organic polymer solidification (Dow  licensee) systems primarily for  the
nuclear industry.

c.  Types of waste treated:  Company has extensive experience with nuclear
wastes, both in solidification and disposal.  Details are available from  the
company.

d.  Types of waste excluded from treatment:  Consult company directly.

e.  Cost of fixation:  Information available from company.

f.  Leach and strength test:  Details on testing with radwastes available.

g.  Examples of past applications and current contracts:  Available directly
from company.
                                      94

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a.  Name of Vendor:  Todd Shipyards Corporation
                     Research and Technical Division
                     P. 0. Box 1600
                     Galveston, Texas  77553

    Contact:  C. E. Winters, Jr., Sales/Marketing Representative
              (800) 2312868/2869       (713) 744-7141

b.  Category of fixing process:  The organic polymer product called  "Safe-T-
Set", is a non-toxic, non-hazardous, powdered, thixotropic  thickner  which  is
effective with concentrated wastes as well as liquids.  Safe-T-Set solidifies
into a homogenous mix with no liquid displacement.  It is not a urea-
formaldehyde formulation.

c.  Types of waste treated:  This product was designed specifically  for  in-
dustrial radioactive waste sludges.  Tests have not been made with general
industrial wastes at this time (Dec 1978).

d.  Type of waste excluded from treatment:  No extensive tests have  been
made.

e.  Approximate cost of processing:  Costs will vary with the amount of  addi-
tive used to solidify the mass.  Typical data given by the  company indicate
that 6 to 20% Safe-T-Set are typical and give hardening time of 14 to  3  min-
utes respectively at 21°C.  The cost of Safe-T-Set is approximately  $6.60/kg
in 500 kg quantities (4/77).  Additive costs (at 10%) would be approximately
$600 per ton of fixed waste.

f.  Data on leach and strength tests supplied by the company:  Extensive
leaching and strength tests are reported by the company.  These tests  were
conducted with simulated radioactive wastes and were designed to prove that
Safe-T-Set, when mixed with radioactive liquid waste, would minimize activity
release if container integrity was lost during transportation or after dis-
posal by burial.  Nine tests were performed:  Escape of radioactive  material
through Safe-T-Set and soil, temperature cycle test, immersion study of  pH
dependance, pH of fixation, immersion study at pH 7.0, off  gas study,  sta-
bility when innoculated with bacteria, irradiation and toxicity.

g.  Examples of past applications and current contracts:  No information
available.

Safe-T-Set is a trademark of Todd Shipyards Corp.
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a.  Name of Vendor:  TRW Systems Group
                     One Space Park
                     Redondo Beach, CA  90278

    Contact:  H. R. Lubowltz, Staff Scientist
              (213) 535-4321

    NOTE;  TRW Company has done extensive testing, development and evaluation
on fixation technology for the EPA.  Data below was taken from Recommended
Methods of Reduction, Neutralization Recovery or Disposal of Hazardous Waste
by Burk, Derham, and Lubowitz of TRW, USEPA contract #68-03-0089, 21 June
1974, and Lubowitz and others, 1977, Development of a Polymeric Cementing
and Encapsulating Process for Managing Hazardous Wastes, EPA-600/2-77-045.

b.  Category of fixing process:  The two types of fixation additives which
were selected for best overall potential and then studied and tested exten-
sively were:

    (1)  Inorganic cements:  Type 2 Portland cement, plaster of paris
(calcium sulfate hemihydrate) and lime (pure calcium oxide).

    (2)  Polybutadiene resins of specific stereo configurations (atactic 1,
2-polybutadiene).

All fixation techniques were tested with and without jackets of both thermo-
plastic and thermosetting resins and asphalt.

c.  Types of waste treated:  All types of solid wastes and sludges were felt
to be treatable, but the specific wastes treated in this study were simulated
solid wastes and sludges containing compounds of six toxic elements: arsenic,
mercury, selenium, chromium, cadmium, and lead.

d.  Wastes not suitable for  treatment:  None given.

e.  Approximate cost or processing:  Process design and economics were
covered extensively in the study.  Details of the design and economics  of
both the organic and inorganic encapsulation processes, cost benefit analysis
and a summary of results were included.  Raw material cost was  the factor
most affecting the process costs and was a primary consideration in the
original selection of the fixation processes.

f.  Data on leach and strength tests:  Extensive tests were made and results
are available.  Tests made included:  mechanical testing, determination of
bulk density, surface hardness, and compressive strength; microscopic exam-
ination of  the interface between fixed specimen and the coating and leaching
experiments using three leaching solutions  (distilled water, saturated  car-
bonic acid  of pH 3.8 to 4.0, and O.lM sodium sesquicarbonate solution).
Leaching was conducted at room temperature in 750 ml of leaching solution
which was mildly agitated twice per day.

g.  Examples of past applications and current contracts:  Not available.


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a.  Name of Vendor:  Werner and Pfleiderer Corp.
                     160 Hopper Ave.
                     Waldwick, NJ  07463

    Contact:  John Stewart or Richard Doyle
              (201) 6528600

    NOTE:  Werner and Pfleiderer Corporation manufactures equipment for  in-
corporating low and intermediate level radwastes into a bitumen or plastic
matrix.  Their equipment and their techniques have been used  in almost all
testing of bitumen encapsulation of hazardous industrial wastes.

b.  Category of fixing process:  The technique used is bitumen encapsulation
or incorporation using a screw extruder.

c.  Types of wastes treated:  No industrial wastes are currently being sta-
bilized by asphalt encapsulation but, testing of asphalt encapsulated
arsenical wastes has been undertaken by the U. S. Environmental Protection
Agency.

d.  Types of wastes excluded from treatment:  Sludges containing strong
oxidizers such as nitrates, chlorates, perchlorates and persulfates should
not be encapsulated in asphalt.  Sludge containing borates may require
special handling because they tend to cause early hardening of asphalt
materials.  Salts that swell excessively on rehydration may require special
processing.

e.  Cost:  Not available for industrial wastes at this time.  Usually wastes
are mixed on 1-to-l weight ratio asphalt to dry wastes.  Asphalt of suitable
grade for blending cost 13 to 35 cents per kg.  Capital, operating expenses
are presently not available for non-radioactive disposal operations.  The
cost of secondary containers (55-gallon steel drums) must also be added  in.

f.  Leach and strength tests:  According to information furnished by the
company, leach rates 100 times less than those observed with  comparable
cement mix can be expected.  If the microdispersed salt/asphalt mix is coated
with as little as 5 mm (0.2 in.) of pure asphalt the leach rate was zero in
distilled water over a period of two and one-half years.  Strength test  data
are not obtained for asphaltic mixes as there are plastic solids that are
usually placed in steel containers.

g.  Examples of past applications and current contracts:  Full scale radwaste
encapsulation units are in operation at Marcoule, France and  Karlsruhe,  West
Germany.  No one is presently using similar equipment in industrial waste
processing.
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                                  APPENDIX B

                       PROPOSED UNIFORM LEACH PROCEDURE
B.I  BACKGROUND

     The leachability of a solidified waste can be considered  to be  a  physi-
cal property of the material much like specific gravity or unconfined  com-
pressive strength.  As such, the leaching characteristics of the solid can
be measured to a high degree of accuracy using uniform or "standard" leach-
ing procedures.  Uniform methodology is needed because leachability  is
specific for the species being leached, the composition and rate of  flow (or
replacement time) of the leaching medium, and other details of  the leaching
vessel and procedure.  The procedure proposed is analogous to  those  used to
determine other physical and/or chemical properties in that environmental
and long-term factors which might effect the property are not  taken  into
account.

     Consideration of the leaching characteristics of a solidified waste
material is also best separated from any environmental factors  which might
be encountered at the disposal site, and from the attributes of any  packag-
ing or jacketing material.  For most purposes, the single most  important
characteristic of the waste solid itself is the rate at which  it will  lose
constituents to the environment, and particularly, to contacting waters—
i.e. its leachability.  For this reason, a wide array of "standard"  leach
tests have been derived for specific waste products and/or conditions  which
have little commonality or theoretical basis.  Comparison of results from
different leach testing procedures is difficult or impossible.

     The Uniform Leach Procedure (ULP) presented here is proposed as a prac-
tical, reproducible, and rapid test which will provide data that can be used
to compare directly the leaching characteristics, different solidified waste
products, and/or to give a quantification of the leaching property of  dif-
ferent production runs of the same treatment process for quality assurance.
It is not proposed to assess parameters which might be significant at  spe-
cific waste disposal sites or for single samples of individual waste
solidication/stabilization processes.  No attempt is made to mimic the
actual conditions that the waste might encounter upon shallow  burial or
other disposal activity.  No accelerating conditions, such as  caustic  leach-
ing media or elevated temperatures are used.  The ULP is designed only to
give a quantitiatve and comparable measure of the waste solid's leachabil-
ity.  It is similar in conception, practice, and interpreation to the  Inter-
national Atomic Energy Agency standard leach test proposed originally  in
1971(C-4) and to its subsequent modifications, such as the "Standard on
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Leachability of Solidified Radioactive Waste" being developed  by  the  Ameri-
can Nuclear Society Working Group ANS-16.1  (0. U. Anders, personal
communication).

     The long-term leaching rate is strongly influenced by many factors  such
as the occurrence of chemical reactions between the leaching fluid  consti-
tuents (such as dissolved C02 or oxygen) and the surface  of the solid,
changes in the leachate pH and erosion, corrosion, or product  spalling or
cracking.  These factors which present the  greatest difficulty to the pre-
diction of the long-term stability of the treated waste product cannot be
approached by short-term leaching tests and require long-term, site-specific
laboratory or field studies to determine.   For specific situations, the  ULP
can be run in conjunction with leaching tests which incorporate site  or
process specific parameters such as leaching medium composition,  temperature
changes, time and numbers of elutions, ratio of leaching  medium volume to
weight of waste, etc.  Results of these site-specific, specialized  leach
tests, when compared to the uniform test results, will serve to estimate the
degree to which the particular disposal conditions will affect the  release
of contaminants from the treated wastes—i.e. their leachability.   Such
leach procedure results, thus "calibrated", can be used to monitor  the con-
tinued effectiveness of the treatment process or variations of it,  over  the
permit period.

     The products of all common solidification/stabilization processes can
be evaluated using the Uniform Leach Procedure.  Wastes treated with  cement,
lime or flyash, asphalt or other organic binders such as  urea-formaldehyde
resin and other plastics, or glass and ceramic materials  and their  com-
posites can be evaluated using the ULP and  the results compared directly
with each other.

B.2 THEORETICAL BASIS OF THE UNIFORM LEACH  PROCEDURE

     Several mechanisms which are responsible for the loss of  constituents
from solid masses have been identified and  described in various studies  of
leaching behavior of solid materials (B-l to B-7).  An early effect in any
leach test is an initial "wash-off" of small particulates adhering  to the
surface of the test speciman in which the concentrations  of most  potential
contaminants are usually very high.  After  this phase, the concentration of
contaminant species in the leachate is determined either  by their maximum
solubility in the leaching medium or by their rate of diffusion to  the sur-
face of the solid where solution can take place.  The ULP incorporates both
an initial rinse or "wash-off" and a relatively short-term  (14 day) static
leaching test.  Results are evaluated using solution or diffusion kinetic
theory.

     The initial "wash-off" portion of the  test produces  a measure  of the
amount of material on the surface of the solidified material which  is not
incorporated into the solid matrix and is thus immediately available  to  the
leaching medium.  This aspect of the leaching of treated  waste products  is
ignored altogether in most test procedures  or simply lumped together  with
the initial leachate samples.  However, it  represents a serious problem  to
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the interpretation of the leaching test  results.   The  "wash-off"  material is
also a separate problem from the longer  term  loss  of contaminants.   The
amount of "wash off" material often can  be modified directly  by attention to
mold design or curing techniques.  Solidified products which  have extremely
high "wash-off" contaminant levels may be refused  or rejected on  this  ground
alone.  The ULP allows airblasting of the product  surface  prior to testing,
these high initial values must represent a highly  mobile surface  deposit.
An initial leach rate which is lower than can be explained by diffusion  or
solution theory may be due to factors such as a delay  in filling  of any
surface voids in the specimen or the presence of a surface film or other
passive surface phenomenon which delays  surface "wetting"  or  interaction
of the surface with the leaching medium.

     Solubility limited constituents in  the leachate samples  typically
follow a pattern in which their concentration remains  relatively  constant at
or near the maximum solubility of the constituent  in the leaching solution.
In this case, the amount of the constituent available  to the  leaching  solu-
tion at the surface of the solid is greater,  or is replaced more  rapidly,
than it is removed by solution in the leaching medium.  Solubility limited
leach rates or leaching kinetics are often found for major constituents  in
the waste or matrix material.  Such is the case for calcium and sulfate  ions
in flue gas cleaning sludges or in many  high  sulfate industrial sludges
which are neutralized with lime.  Constituents present in  low concentration
in the waste but which have low solubility can also exhibit solubility
limited leaching kinetics.  For example, many heavy metals have constant
leach rates in leaching tests made with  alkaline,  treated  or  untreated,
industrial sludges (B-6).  Minor variations in the pH, temperature, or
presence of other competing ions in the  leaching medium can cause rapid  and
erratic concentration changes of solubility limited leachate  constituents by
causing major changes in the solubility  of the leaching species.   Depletion
of the low solubility constituents from  the surface of the solidified  waste
will cause a change to internal diffusion-limited  kinetics.

     Those constituents which have solubility in the leaching medium higher
than their availability for solution at  the surface of the solid  matrix  show
leaching kinetics which are described by classical diffusion  theory—the
rate of their appearance at, and solution from, the surface being dependent
upon the rate of their diffusion from inside  the matrix of the solidified
waste to the surface.  These internal diffusion-limited leachate  constitu-
ents have high initial concentrations which decrease over  time due to  the
depletion of the constituent in the surface layers of  the  solid matrix.

     Solution of the mass transport equations for  diffusion of a  constituent
from a semi-infinite medium  (the waste-containing  solid) has  been shown  to
give the following expression (B-2):
                                            h
                             £A      9C  / D
                             	n   =  2S  I e
                              A       V  \ 7T
                               o         ^
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 where

      LA  = total amount lost  in  (n)  leaching  periods,  mg
        n
       A  = initial amount in  specimen, mg
        o

        t = lapsed time to (n) sample,  sec

                                     2
        S = exposed surface area, cm
                      3
        V = volume, cm

                                                                 2
       D  = effective diffusivity (or diffusion  coefficient),  cm /sec
        e

 Equation (1) upon rearrangement yields:



                                      /ZA  (V) \2
                                    M
-------
 where
      At -
  A  = amount of constituent lost in leaching period (n), mg

 At  = duration of (n) leachate renewal period, sec

t /2 = elapsed time at middle of (n)leachate renewal period, sec
 Solving Equation (3) for the diffusion coefficient, D  , yields:
                          D
                                            t -
                                              At
                                                                (4)
     For specimens which have high initial "wash-off" levels of  the  leaching
species, a correction for the initial amount can be made by either leaving
that value out of the accumulated fraction leached or by using the
relationship:
                                A
                                                                           (5)
Where  (A /A ) is the fractional amount of the constituent  lost  in  the
initial rapid "wash-off" operation.  Use of- the incremental mass  loss
(Equations 3 and 4) will also alleviate problems with high  or  low initial
losses.

     The amount of the species of interest leached  (referred to  as  £A  /A
or A /A ) is dependent upon both the shape and the  size of  the leaching
specimen.  To compare between leach tests using differently shaped  and  sized
waste solids, the equations for the amount leached  incorporate the  speci- „
men's surface to volume ratio (S/V).  Thus, the values of surface area  (cm )
and volume (cm ) must be known accurately so that meaningful comparisons  of
the data can be made.

B.3  THE LEACH TEST PROCEDURE

     The ULP intentionally prescribes a detailed protocol to be  followed
explicitly as to leaching medium composition, leachate renewal frequencies,
and other test conditions such as temperature and pressure.  The major  pur-
pose of the ULP is to determine the effective diffusivity of the solidified
material as supplied for comparative or quality assurance purposes.   Other
testing conditions and leaching medium compositions may be  required to  more
nearly represent anticipated conditions under which the specific waste  may
be disposed; but such tests are not part of the ULP as proposed  here.   The
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ULP is designed to be accomplished as reproducibly, and as  simply  and
quickly as possible.

Specimen Preparation
     The waste to be solidified should be thoroughly mixed  to  assure a rep-
resentative sample is used and should undergo preparative treatment as close
to that experienced by the actual treated waste product as  possible.   Core
drilling of large waste forms may be used to prevent edge effects  in the
small molds or disparity in treatment techniques due to scaling  effects.
The solid specimen must have a defined and known size and shape  (such  as  a
monolithic cylinder, parallelepiped or sphere).  Cylinders  must  have
diameter-to-length ratios, and parallelpipeds a minimum thickness-to-length
ratios, of from 0.2 to 5.  A cylindrical shape is preferred.   The  minimum
dimension in any direction is 1 cm.  All details of solidification, casting,
curing, and storage conditions and containers shall be reported.

     The surface of the specimen must be smooth, without voids,  and homo-
geneous so that the calculated surface area approximates the true  surface
exposed to the leaching medium.  The surface should not be  washed  or wetted
before testing but may be air blasted to remove lose particles and dust.

Leaching Test Vessel

     No specific vessel shape or dimensions are required, but  the  following
points must be noted.  The vessel must be nonreactive with  respect to  the
leachate and the waste test specimen and must not adsorb species of interest
during the leaching test.  It must prevent excessive evaporation of leachate.
The geometry of the vessel must allow all of the external surface  of the
specimen to be exposed to the leaching medium using the volume of  leachate
specified below and to have sufficient free space to allow  handling of the
leachate and the test specimen.  Sufficient space must be available in the
vessel so that the test specimen is surrounded on all sides by leaching
medium at a depth equal to or greater than the smallest specimen dimension.
A support for the test specimen to rest upon must be provided  in the vessel;
it must not interfere with leachate addition or removal, cause damage  to  the
specimen, or cover more than 2% of the surface of the specimen.

Leaching Medium

     The leaching medium used in all Uniform Leach Procedures  is deminera-
lized water with an electrical conductivity of less than 10   mho/cm at 25°C
and a total organic carbon content of less than 5 ppm.  The leaching medium
should be equilibrated with air so that it is saturated with respect to
oxygen and carbon dioxide, and has a pH of between 4 and 5.5.

     The volume of leaching medium used for each leaching interval shall  be
related to the surface area of the specimen by the following relationship:

                             3                  2
          leaching medium (cm )/surface area (cm ) = 10.0

     This ratio was selected as a compromise between having sufficient


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volume to minimize leachate changes and solubility  limits  during  the  short
leachate-renewal intervals and having a small enough volume  to  produce
measurable changes in concentrations of the  leached species  analyzed.

Test Procedures

Initial Rinse—
     An initial rinse or "wash-off" of the test  specimen shall  be made  be-
fore the actual leaching is begun.  The specimen is immersed in one leachate
volume (see above) for 30 seconds, then removed  and placed in the leaching
vessel.  This initial rinse volume is analyzed for  all  constituents of
interest.  The analytical results are presented  in  the  report section.

Changing the Leaching Medium—
     The following procedure should be followed  at  the  end of each leaching
interval.  The leachate should be removed from the  leaching  vessel, divided
into necessary aliquots and preserved for analysis.  The leachate should be
stirred to suspend any particulates before sample splits are made since the
analyses to be made should include particulate as well  as  dissolved mate-
rials.  Precipitation which occurs in the leachate  during  the leaching
interval must also be included in the analyses.   The leachate should  not be
filtered to remove particulates.  In some cases,  the leachate will have to
be acidified to make representative samples.

     The leaching vessel (but not the test sample)  should  be rinsed in
demineralized water to remove all traces of  the  previous leachate. The test
specimen should be exposed to the air for as  short  a time  as possible;  in no
case shall its surface be allow  to dry.  The  leaching medium (demineralized
water) for the next leach interval is then added and the apparatus left for
the next time interval.  The leachate is not  agitated or stirred  during the
leaching interval.

     An alternative method which may be employed if practical is  to remove
the test specimen from the leaching vessel and to quickly  place it in a new,
freshly.rinsed leaching vessel.  Care should  be  taken to not scar or  scratch
the specimen surface  (or to drop it) during  the  operation.  In  all cases the
leachate should be preserved and analyzed as  soon as possible.

Leachate Replacement Frequency—
     Since the length of the time intervals  between leachate renewal  will
affect the rate of constituent release  (B-l,  B-2) and therefore the diffu-
sion coefficient found, a uniform replacement schedule  is  required.   The
leachate shall be replaced completely after  cumulative  leaching times of 2,
7, and 24 hours after initiation of  the test.  Further  leachate replacements
are to be made at 24 hour intervals  for the  next 4  days and then  at  72  hour
intervals for the next 9 days which  completes the ULP testing for that  speci-
men.  This procedure gives  10 data points—three in the first 24  hours, 7 in
the first 5 days—to evaluate the leaching characteristic  of the  solidified
waste product.  The procedure is completed in 14 days.
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B.4  ORGANIZATION AND PRESENTATION OF THE RESULTS

     The results of the ULP include all of  the  details  of  the  procedure as
actually used so that adequate comparisons  can  be made  with  the  results of
ULP tests performed on other materials made by  other  treatment processes or
at different times.  The following list includes the  principal information
required.  Items should be reported in the  order that they appear  below.

     a.  Waste description;  The type and source of waste, its percent
solids, and its composition in mg/kg dry solids of all  constituents  of
interest should be presented in as much detail  as practical.

     b.  Treatment description;  The type and composition  of the solidifi-
cation reagents including all additives; proportion of  waste solids  and
treatment reagents and additives in the final solid waste  product  (on a
weight/weight basis) should be included.  Any deviations from  standard
preparation methods must be given.

     c.  Test specimen preparation;  The method of specimen preparation
should include mold type and releasers used, or coring  procedures.   The
shape, mass, and accurate dimensions of the actual leaching specimen, the
history of the specimen between preparation and leaching including time
since preparation, temperature during curing, humidity  during  curing and
storage, container(s) used, and any other relevant information should also
be reported.

     d.  Leaching test procedures;  For each leaching interval—report  time
to nearest minute and date of beginning and end of interval, electrical con-
ductivity and temperature of leachate removed and of  the new leaching medium.
The volume of leaching medium used, and treatment of aliquots  made up and
preserved for analysis must be reported.

     e.  Integrity of test specimen;  Appearance of the surface  of the  speci-
men before and after leaching; observed changes in shape or dimensions,  and
nature and description of any particulates  or precipitates in  the  leachate
must be included in the formal test results.

     f.  Analytical results;  Tables must be prepared that include the  con-
centration (in mg/f) of each constituent of interest  (see  below) present in
each leachate sample including the initial  rinse, the amount of  each con-
stituent in each leachate sample (multiply  the  concentration in  mg/f  times
leachate volume in t to give mass in mg), the fraction  of  the  constituent
present in the test specimen which has been leached in  each sample,  and the
accumulated mass and fraction leached in the composite  leachate  samples and
in the initial rinse, and the accumulated masses corrected for the volume-
to-surface area ratio for comparison purposes,  (ZA /A  ) (V/S).
                                                   n  o
     g.  Diffusion coefficient (effective diffusivity);  The diffusion  coef-
ficient (D ) as computed by any of the methods  and equations given above, or
any description of the variation in D  if no single value  can  be logically
calculated must be presented in the test results.
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B.5  INTERPRETATION OF RESULTS OF ULP

     After the initial removal of mobile surface  constituents  in  the  rinse
procedure, the early leach rates observed with solidified waste products
most often fit kinetics best explained by internal diffusion within the
solid matrix.  Other mechanisms such as erosion,  spalling, corrosion,  or
dissolution are not usually important until  longer leaching periods have
elapsed.  Until about 20% of a leachable species  has been lost from a uni-
form, regular shaped solid, its leaching behavior when diffusion  controlled
approximates that for a semi-infinite medium (B-l).

     The mean value of the 10 diffusion coefficients (D  ) calculated  from
the 10 leaching intervals (Equation 4, above) is  the experimental value best
describing the leaching properties of the waste solid.   Ranges in values
calculated for the diffusion coefficient using this technique which are
greater than about 25% are considered to be  excessive.   In cases  where vari-
ation of D  is large, another specimen should be  tested  or other  explana-
tions, sucn as solubility limitations or high initial values, be  pursued.
Another test of the validity of the data set can  be made by comparing the
mean of the first five D  values with the mean of the last five values; if
these means vary more than about 5%, the data should be  considered as biased
and further tests made to verify the bias.

     If single-parameter diffusion is the only leaching  mechanism, the
solidified waste is homogeneous and stable over the test period,  then the
diffusion coefficient has specific meaning.  Using it, the rate of loss of
the constituent in question can be predicted from large  waste  form under
similar conditions and long-term movement of the  constituent in the waste
mass can be estimated.  However, these theoretically derived models of
simple, internal diffusion hold exactly only when:

     a.  The leaching medium is continuously moving and  does not  change in
composition or character significantly.

     b.  The solidified waste material is homogenous and remains  chemically
and physically unchanged, and its surface is smooth and  does not  deteriorate
with time.

     c.  The leachable species is rapidly mobilized by the leaching medium
so that bulk diffusion is the limiting process.

     d.  No chemical interactions between the leaching species and  the
leaching medium, the matrix, or other leaching constituents occur.

     e.  The leaching species is present in  but one chemical and  physical
form.

     Surface irregularities and roughness,  swelling, fissuring,  surface
deterioration, and chemical or physical breakdown of the matrix material  all
will increase the rate of loss of the leaching species.   Irregular  or
stagnant leachate flow which allows build up of the concentration of  the


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leaching species in the leaching medium, curing  or  chemical  changes  which
influence the diffusivity in the matrix, or the  presence  of  inhomogeneous
portions of the matrix all tend to retard  the  leaching  loss.   The  effective
diffusivity should be considered a purely  material  property  of  the waste
solid like density or heat capacity.  Knowledge  of  its  value is important to
the prediction of the leaching properties  of the waste  solid,  but  its  use
required judgment and a thorough knowledge of  other parameters  of  the  waste
material and the environment to which it will  be subjected.
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                                 REFERENCES
B-l.  Anders, 0. U., J. F. Bartel, and S. J. Altschuler.  Determination  of
      Leachability of Solids.  Analytical Chemistry.  50:564-569.   1978.

B-2.  Godbee, H. W. and D. S. Joy.  Assessment of  the Loss  of  Radioactive
      Isotopes from Waste Solids to the Environment.  Part  1:   Background
      and Theory.  ORNL-TM-4333.  Oak Ridge National Laboratory,  Oak  Ridge,
      TN.  February, 1974.

B-3.  Godbee, H. W. et al.  Application of Mass Transport Theory  to the
      Leaching of Radionuclides from Waste Solids.  Nuclear and Chemical
      Waste Management.   1:29-35.  1980.

B-4.  International Atomic Energy Agency.  Leach Testing of Immobilized
      Radioactive Waste Solids, A Proposal for a New Standard  Method.  In:
      Atomic Energy Review, Vol 9, pp. 195-207.  E. D. Hespe,  Ed.  1971.

B-5.  Johnson, J. C. and R. L. Lancione.  Assessment of Processes to  Stabi-
      lize Arsenic-Laden Wastes,  pp. 181-186.  In:  Disposal  of  Hazardous
      Waste.  EPA-600/9-80-010.  Environmental Protection Agency,  Cincinnati,
      OH.  March, 1980.

B-6.  Jones, L. W. and P. G. Malone.  Physical Properties and  Leach Testing
      of Solidified/Stabilized Flue Gas Cleaning Wastes.  U. S. Environmental
      Protection Agency, Cincinatti, OH.  (in press).

B-7.  Moore, J. G., H. W. Godbee, and A. J. Kibbey.  Leach  Behavior of Hydro-
      fracture Grout Incorporating Radioactive Wastes.  Nuclear Technology.
      32-39-52.  January, 1977.
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                                  GLOSSARY
     NOTE:  The following terms are defined as in the Environmental Protec-
tion Agency, Rules and Regulations:  Hazardous Waste Management  System
which appeared in the Federal Register on May 19, 1980; Vol 45,  pages  33073-
33076.
     Definitions of terms not officially published in EPA regulations  but
germane to this manual (such as solidification, fixation, etc.)  are dis-
cussed in Section 1.2.

aquifer:  a geologic formation, group of formations, or part  of  a  formation
     capable of yielding a significant amount of groundwater  to  wells  or
     springs.

confined aquifer:  an aquifer bounded above and below by impermeable beds  or
     by beds of distinctly lower permeability than that of the aquifer
     itself; an aquifer containing confined groundwater.

container:  any portable device in which a material is stored, transported,
     treated, disposed of, or otherwise handled.

contingency plan:  a document setting out an organized, planned, and coordi-
     nated course of action to be followed in case of a fire, explosion, or
     release of hazardous waste or hazardous waste constituents  which  could
     threaten human health or the environment.

designated facility:  a hazardous waste treatment, storage, or disposal
     facility which has recieved an EPA permit (or a facility with interim
     status) in accordance with the requirements of 40 CFR Parts 122 and
     124, or a permit from a State authorized in accordance with Part  123.

dike:  an embankment or ridge of either natural or man-made materials  used
     to prevent the movement of liquids, sludges, solids, or  other materials.

discharge (or hazardous waste discharge):  the accidental or  intentional
     spilling, leaking, pumping, pouring, emitting, emptying, or dumping of
     hazardous waste into or on any land or water.

disposal:  the discharge, deposit, injection, dumping, spilling, leaking,  or
     placing of any solid waste or hazardous waste into or on any  land or
     water so that such solid waste or hazardous waste or any constituent
     thereof may enter the environment or be emitted into the air  or dis-
     charged into any waters, including ground waters.
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disposal facility:  a facility or part of a facility at which hazardous
     waste is intentionally placed into or on any land or water, and at
     which waste will remain after closure.

existing hazardous waste management facility:  a facility which was in op-
     eration, or for which construction had commenced, on or before October
     21, 1976.  Construction had commenced if:

          (i)  The owner or operator has obtained all necessary Federal,
               State, and local preconstruction approvals or permits; and
               either

          (ii)(a) A continuous physical, on-site construction program has
               begun, or

              (b) The owner or operator has entered into contractual
               obligations—which cannot be cancelled or modified without
               substantial loss-for construction of the facility to be
               completed within a reasonable time.

facility:  all contiguous land, and structures, other appurtenances, and
     improvements on the land, used for treating, storing, or disposing of
     hazardous waste.  A facility may consist of several treatment, storage,
     or disposal operational units (e.g., one or more landfills, surface
     impoundments, or combinations of them).

food-chain crops:  tobacco, crops grown for human consumption, and crops
     grown for feed for animals whose products are consumed by humans.

freeboard:   the vertical distance between the top of a tank or surface  im-
     poundment dike, and the surface of the waste confined therein.

free liquids:  liquids which readily separate from the solid portion of a
     waste under ambient temperature and pressure.

generator:   any person, by site, whose act or process produces hazardous
     waste identified or listed in EPA regulations.

groundwater:  water below the land surface in a zone of saturation.

incinerator:  an enclosed device using controlled flame combustion, the
     primary purpose of which is to thermally break down hazardous waste.
     Examples of incinerators are rotary kiln, fluidized bed, and  liquid
     injection incinerators.

incompatible waste:  a hazardous waste which  is unsuitable for:

          (i)  Placement in a particular device or facility because it  may
               cause corrosion or decay of containment materials  (e.g.,
               container inner liners or tank walls); or
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          (ii) Commingling with another waste or material under uncontrolled
               conditions because the commingling might produce heat or
               pressure, fire or explosion, violent reaction, toxic dusts,
               mists, fumes, or gases, or flammable fumes or gases.

individual generation site:  the contiguous site at or on which one or more
     hazardous wastes are generated.  An individual generation site, such as
     a large manufacturing plant, may have one or more sources hazardous
     waste but is considered a single or individual generation site if the
     site or property is contiguous.

in operation:  refers to a facility which is treating, storing, or disposing
     of hazardous waste.

injection well:  a well into which fluids are injected.  (See also "under-
     ground injection.")

inner liner:  a continuous layer of material placed inside a tank or con-
     tainer which protects the construction materials of the tank or con-
     tainer from the contained waste or reagents used to treat the waste.

landfill:  a disposal facility or part of a facility where hazardous waste
     is place in or on land and which is not a land treatment facility, a
     surface impoundment, or an infection well.

landfill cell:  a discrete volume of a hazardous waste landfill which uses a
     liner to provide isolation of wastes from adjacent cells or wastes.
     Examples of landfill cells are trenches and pits.

land treatment facility:  a facility or part of a facility at which hazard-
     ous waste is applied onto or incorporated into the soil surface; such
     facilities are disposal facilities if the waste will remain after
     closure.

leachate:  any liquid, including any suspended components in the liquid,
     that has percolated through or drained from hazardous waste.

liner:  a continuous layer of natural or man-made materials, beneath or on
     the sides of a surface impoundment, landfill, or landfill cell, which
     restricts the downward or lateral escape of hazardous waste, hazardous
     waste constituents, or leachate.

hazardous waste management:  the systematic control of the collection,
     source separation, storage, transportation, processing, treatment,
     recovery, and disposal of hazardous waste.

manifest:  the shipping document originated and signed by the generator
     which contains the information required by EPA regulations.

manifest document number:  the serially increasing number assigned to the
     manifest by the generator for recording and reporting purposes.
                                     Ill

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mining overburden returned to the mine site:  any material overlying an
     economic mineral deposit which is removed to gain access  to  that de-
     posit and is then used for reclamation of a surface mine.

movement:  that hazardous waste transported to a facility in an individual
     vehicle.

new hazardous waste management facility:  a facility which began  operation,
     or for which construction commenced after October 21, 1976.   (See also
     "Existing hazardous waste management facility.")

on—site:  the same or geographically contiguous property which may  be divided
     by public or private right-of-way, provided the entrance  and exit be-
     tween the properties is at a cross-roads intersection, and access is by
     crossing as opposed to going along, the right-of-way.  Non-contiguous
     properties owned by the same person but connected by a right-of-way
     which he controls and to which the public does not have access, is also
     considered on-site property.

open burning:  the combustion of any material without the following charac-
     teristics:

          (i)  Control of combustion air to maintain adequate  temperature
               for efficient combustion.

          (ii) Containment of the combustion-reaction in an enclosed device
               to provide sufficient residence time and mixing for  complete
               combustion, and

          (iii) Control of emission of the gaseous combustion  products.

          (See also "incineration" and "thermal treatment.")

operator:  the person responsible for the overall operation of a  facility.

owner:  the person who owns a facility or part of a facility.

personnel (or facility personnel):  all persons who work at, or oversee  the
     operations of, a hazardous waste facility, and whose actions may  result
     in noncompliance.

pile:  any noncontainerized accumulation of solid, nonflowing  hazardous
     waste that is used for treatment or storage.

point  source:  any discernible, confined, and discrete conveyance,  includ-
     ing, but not limited to any pipe, ditch, channel, tunnel, conduit,
     well, discrete fissure, container, rolling stock, concentrated animal
     feeding operation, or vessel or other  floating craft,  from which  pol-
     lutants are or may be discharged.  This  term does not  include return
     flows from irrigated agriculture.
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publicly owned treatment works (or POTW):  any device or system used  in  the
     treatment (including recycling and reclamation) of municipal sewage or
     industrial wastes of a liquid nature which is owned by a State or munic-
     ipality.  This definition included sewers, pipes, or other conveyances
     only if they convey wastewater to a POTW providing treatment.

representative sample:  a sample of a universe or whole (e.g., waste  pile,
     lagoon, ground water) which can be expected to exhibit the average
     properties of the universe or whole.

run-off:  any rainwater, leachate, or other liquid that drains over land
     from any part of a facility.

run-on:  any rainwater, leachate, or other liquid that drains over land  onto
     any part of a facility.

saturated zone (or "zone of saturation"):  that part of the earth's crust  in
     which all voids are filled with water.

sludge:  any solid, semisolid, or liquid waste generated from a municipal,
     commercial, or industrial wastewater treatment plant, water supply
     treatment plant, or air pollution control facility exclusive of  the
     treated effluent from a wastewater treatment plant.

storage:  the holdings of hazardous waste for a temporary period, at  the end
     of which the hazardous waste is treated, disposed of, or stored
     elsewhere.

surface impoundment (or impoundment):  a facility or part of a facility
     which is a natural topographic depression, man-made excavation,  or
     diked area formed primarily of earthen materials (although it may be
     lined with man-made materials), which is designed to hold an accumula-
     tion of liquid wastes or wastes containing free liquids, and which  is
     not an injection well.  Examples of surface impoundments are holding,
     storage, settling, and aeration pits, ponds, and lagoons.

tank:  a stationary device, designed to contain an accumulation of hazardous
     waste which is constructed primarily of non-earthen materials (e.g.,
     wood, concrete, steel, plastic) which provide structural support.

thermal treatment:  the treatment of hazardous waste in a device which uses
     elevated temperatures as the primary means to change the chemical,
     physical, or biological character or composition of the hazardous
     waste.  Examples of thermal treatment processes are incineration,
     molten salt, pyrolysis, calcination, wet air oxidation, and microwave
     discharge.  (See also "incinerator" and "open burning.")

totally enclosed treatment facility:  a facility for the treatment of haz-
     ardous waste which is directly connected to an industrial production
     process and which is constructed and operated in a manner which  pre-
     vents the release of any hazardous waste or any constituent thereof


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       into the environment during treatment.  An example  is  a pipe in which
       waste acid is neutralized.

  transportation:  the movement of hazardous waste by  air,  rail,  highway, or
       water.

  transporter:   a person engaged in the offsite  transportation of hazardous
       waste by air, rail, highway, or water.

  treatment:  any method, technique, or process, including neutralization,
       designed to change the physical, chemical, or biological character or
       composition of any hazardous waste so as  to neutralize such waste, or
       so as to recover energy or material resources from  the waste,  or so as
       to render such waste non-hazardous, or less hazardous; safer to trans-
       port, store, or dispose of; or amenable for recovery,  amenable for
       storage, or reduced in volume.

  underground injection:  the subsurface emplacement of  fluids through a
       bored, drilled or driven well; or through a dug well,  where the depth
       of the dug well is greater than the largest surface dimension.  (See
       also "injection well.")

  unsaturated zone  (or zone of aeration):  the zone between the land surface
       and the water table.

  well:  any shaft or pit dug or bored into  the  earth, generally of a cylin-
       drical form, and often walled with bricks or tubing to prevent the
       earth from caving in.
                         ;.':•,« Agency
*U.S. GOVERNMENT PRINTING OFFICE: 1982 0-361-082/320           1 14

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