DIRECTIVE NUMBER:
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            APPROVAL DATE:


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            ORIGINATING OFFICE: office of solid Waste
             STATUS: 'A
            REFERENCE (other documenU):
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                          OSWER Policy Directive 39487.00-2A
PROHIBITION ON THE  PLACEMENT OF BULK LIQUID




      HAZARDOUS WASTE  IN LANDFILLS -




    -STATUTORY INTERPRETIVE GUIDANCE-
            March  31,  1986
   U.S. Environmental  Protection Agency

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                                      OSWER Policy Directive 39487.00-2A








                      TABLE OF CONTENTS








Section 1 - Introduction	    1-1



Section 2 - Statutory Requirements	    2-1



     Bulk Liquid Hazardous Wastes Prohibited	    2-1



     Use of Absorbents	    2-3



     Location of Mixing Facility.;	    2-6



Section 3 - Guidance	    3-1



     General Guidance	    3-1



     Absorbents	    3-3



     Treatment Technoloqies	    3-6



           Liquid-Solid Separation Processer	    3-6



           Biological Treatment	    3-7



           Thermal Treatment	    3-8



           Chemical Treatment	    3-8



     Test Methods	    3-11



     Time Factor	    3-19



     Implementation	    3-20



     References	    3-21

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                                      OSWER Policy Directive //9487.00-2A


                      LIST OF EXHIBITS


Exhibit 1 - Bulk Liquids  Testing Procedures	   3-12

Exhibit 2 - Compressive Strength Data	   3-16

Exhibit 3 - Unconfined Compressive Strength of Stabilized  ....   3-18
                 Soils
                               11

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for Review


Date
                                                   Informat on
           Prohibition on  the Disposal of  Bulk Liquid Hazardous Waste in Landfills
                             Statutory Interpretive Guidance
Summary ot Directive
       This document was written in order to provide guidance to owners  and operators
       of hazardous waste landfills who  dispose  of bulk  liquid hazardous wastes.
        •Hie document addresses  Section 3004(c)(1)  of RCRA.   The  document will
        ensure that owners and  operators will understand the legal requirements of
        the provision along with the technical requirements.
Key Words:
             Hazardous  waste Landfills,  Bulk Liquids, Chemical  Stabilization,  & Absorption
Type of Directive {Manual. Policy Directive. Announcement, etc.I
               Guidance Manual
             ' Status
             I
                                                                      D Draft
                                                                      ED Final
                                                                      D New
                                                                      L_l Revision
Does- this Directive Supersede Previous Directives;'   |  | Yes  K I  No   Does It Supplement Previous DirtctivMsl'   |  | Y«s   fX| No
K "Yes" to Either Question. What Directive (number, title!
Review Plan
   uD AA-OSWER
   E?OSW
D OUST
03 OWPE
LM Regions
OECM
OGC
                                                   I_J
Oiner (Specify/
This Request Meets OSWER Directives System Format
Signature o) Lead Office Directives Officer
                                                                                i Date
Signature of OSWER Directives Officer
                         TOate

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                                          OSWER Policy Directive //9487.00-2A
            UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

                        WASHINGTON, D.C. 20460
                           MAY   I !9Sc
MEMORANDUM
         OFFICE OF
SOLID WASTE AND EMERGENCY RESPONSE
SUBJECT:  Statutory Interpretive Guidance—Treatment  of
          Bulk Liquid Hazardous Wastes

FROM:     Marcia E. Williams,  Director
          Office of Solid Waste  (WH-562

TO:       J. Winston Porter
          Assistant Administrator  (WH-562A)


     I am submitting for .your  approval the attached guidance
document for the bulk liquid hazardous waste  provision of  the
Hazardous and Solid Waste Amendments  (HSWA) of  1984.  The
guidance discusses methods for the  treatment  of  bulk  liquid
hazardous wastes.

     In March, 1985, the Regions,  States, and members of the
regulated community were given an  opportunity to comment on
our first draft of this guidance.   On May 9,  1985, we distributed
a redraft that incorporated those  comments received.  This
final version of the guidance  is necessary to further clarify
the distinction between the terms  "absorption"  and "adsorption"
and to provide an objective test and  criteria to distinguish
between a chemical stabilization process and  a  process that is
solely physical treatment by a sorbent.

     Also attached is a memorandum  for you to transmit this
guidance for Red Border and OMB review, so that we can notice
it in the Federal Register.  Paul  Cassidy, in the Land Disposal
Branch, can respond to any technical  questions  that your staff
may have on the guidance.  He  can  be  reached  at 382-4682.

Attachments

cc:  John P. Lehman

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                                            OSWER Policy Directive //9487.00-2A

            UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
                        WASHINGTON, D.C. 20460
                           MAY  91986
                                                         OFFICE OF
                                                SOLID WASTE AND EMERGENCY RESPONSE
MEMORANDUM
SUBJECT:  Submission  of  Statutory  Interpretive  Guidance  for
          Red Border  and OMB  Review—Treatment  of  Bulk Liquid
         .^Hazardous Wastes
FROM:
          Assistant Administrator  (WH-562A)

TO:       Milton Russell, Assistant Administrator
            for Policy,  Planning,  and  Evaluation  (PM-219)


     I am submitting for Red Border and OMB  review  the  attached-
guidance concerning the  bulk liquid hazardous waste provision
(Section 3004(c)(D) of  the Hazardous  and  Solid Waste Amendments
(HSWA) of 1984.  The guidance  discusses methods for the treat-
ment of bulk liquid hazardous  wastes,  and  addresses the legal
requirements of the provision.
BACKGROUND

     The provision prohibits  the placement of  bulk  liquid
hazardous wastes in landfills  (whether or not  absorbents have
been added) after May 8,  1985.  Congress was particularly
concerned with the use of materials that function solely as
absorbents as a treatment method for  bulk liquid hazardous
wastes.  Congress was concerned with  absorbents because they
may release the absorbed  liquid back  to the environment.  The
legislative history to this provision suggests that processes
such as chemical stabilization that,  unlike absorbents, render
liquids permanently unavailable to the environment, should be
deemed appropriate forms  of pretreatment for liquid hazardous
wastes.

CONTENT OF GUIDANCE

     The guidance lists the following acceptable forms of
treatment for bulk liquid hazardous wastes.  These  treatment
methods are not meant to  be all inclusive.

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                                      OSWER Policy Directive //9487.00-2A
     1.  Liquid-Solid Separation Processes

         a.  sedimentation or decanting
         b.  flotation
         c.  filtration
         d.  centrifugation
         e.  evaporation
         f.  distillation

     2.  Chemical Treatment

         a.  chemical stabilization

     3.  Biological Treatment

         a.  activated sludge systems
         b.  trickling filters

     4.  Thermal Treatment

         a.  liquid injection incineration
         b.  rotary kiln incineration

     The guidance provides a definition for the terms "absorbent"
and "'adsorbent."  "Absorbent" is defined in the guidance, as a
material that is capable of holding a liquid throughout the
body of the absorbing material.  In an absorbent, the liquid
penetrates into the inner structure of the absorbing material.
"Adsorption" is a process where the liquid adheres to the
surface of the adsorbing material.  Adsorption is the result of
intermolecular attractive forces between the adsorbent and the
adsorbed liquid.  The intermolecular forces of attraction are
normally weak, and the phenomenon is therefore readily reversible.
In certain instances, a chemical interaction between the adsorbent
and adsorbed liquid may occur and this is called chemisorption.

     The guidance specifies that neither absorption nor adsorp-
tion involves a chemical transformation of the sorbed liquid
(with the exception of chemisorption).  Since Congress was
concerned with treatment methods that failed to render wastes
unavailable to the environment, the guidance states that the
ban on "absorbents" has been interpreted to include materials
that sorb wastes through either absorption or adsorption.  The
guidance further lists examples-of banned sorbents.

     The guidance states that the Paint Filter Liquids Test
(issued by EPA on April 30, 1985, in 50 FR 18370) must be used
to determine the presence or absence of liquids or free liquids
in a waste sample.  If the waste passes the Paint Filter Liquids
Test, the material is not subject to this prohibition and can
be landfilled provided it is not prohibited because of the use
of a sorbent.  If the waste fails the Paint Filter Liquids Test
(i.e., contains liquids or free liquids), additional treatment,

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                                      OSWER Policy Directive //9A87.00-2A
consistent with  this  guidance,  is  required.  After  such  treatment,
the waste must pass the  Paint Filter  Liquids Test before  it  is
allowed  to be landfilled.

     The guidance  also discusses these  situations:   1) a  spill
of a hazardous waste, and  2) soils contaminated by  a spill.  A
spill of a hazardous  waste is not  allowed to be placed in a
landfill, in a bulk form,  if a  sorbent  is used to clean up the
spill.   We believe that  the statute prohibits this  type of con-
duct.  On the other hand,  we believe  that the ban on landfilling
sorbed wastes was  not intended  to  encompass soils contaminated
by accidental spills  into  the ground.   Consequently, unintentionally
contaminated soils may be  landfilled  if the contaminated  soil
(without the addition of an absorbent)  passes the Paint Filter
Liquids  Test.

     The guidance  has also been revised to include  a reference
to an ASTM Unconfined Compressive  Strength Test.  This test
and the  criteria to pass the test were  developed to aid permit
writers  in distinguishing  between  a chemical stabilization
process  and a process that is solely  physical treatment by a
sorbent.  It is often difficult to determine whether a particular
process  involves stabilization  or  is  merely sorption.  EPA
expects  owners and operators to demonstrate that chemical
transformations have  occurred.  The owner or operator should
submit laboratory  data showing  that the appropriate "recipe"
has been developed.   If, however,  it  is not apparent to the
permit writer that chemical stabilization has occurred, then
the unconfined compressive strength test is recommended as a
means of demonstrating chemical stabilization.

DEVELOPMENT OF GUIDANCE

     In  March, 1985,  the Regions, States, and members of the
regulated community were given  an opportunity to comment on
our first draft of this guidance.  Twenty sets of comments
were received.  The comments addressed  such items as spills of
liquid wastes, the appropriate  time to  conduct the  Paint Filter
Liquids  Test, and  generator certification.

     On  May 9, 1985,  we distributed a redraft that  incorporated
those comments previously  received.  The May 9, 1985, redraft
was also submitted to Red  Border for  review.  During Red Border
review,  we received comments that addressed the need for a clearer
discussion concerning the  technology  of chemical stabilization.
We also  received comments  concerning our definitions of the
terms "absorbent"  and "adsorbent", and  our guidance language
dealing  with the spill of  a waste vs. the spill of  a product.
All of these areas of concern have been addressed through the
work group process.

     This guidance was also developed through the work group on
bulk liquid hazardous wastes, which had representatives from
the following offices:  Office  of General Counsel,  Office of

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                                      OSWER Policy Directive //9487.00-2A
Policy Analysis, Office  of  Enforcement and Compliance  Monitoring,
Office of Waste Programs Enforcement, and Office of  Solid  Waste.

Attachment

cc:  Marcia Williams
     Gene Lucero
     Henry Longest

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                                        OSWER Policy Directive //9487.00-2A
                            SECTION I
                          INTRODUCTION
     On November 8, 1984, the Hazardous and Solid Waste Amendments

of 1984 were signed into law.  Section 3004 (c)(l) addresses

bulk liquid hazardous waste in landfills.  This provision

states that:

     Effective 6 months after the date of enactment of the
     Hazardous and Solid Waste Amendments of  1984, the
     placement of bulk or noncontainerized liquid hazardous
     waste or free liquids contained in hazardous waste
     (whether or not absorbents have been added) in any
     landfill is prohibited.

     The bulk liquid hazardous waste provision became effective

on May 8, 1985.  The Agency is issuing this guidance to

ensure that owners and operators of hazardous waste landfills

regulated under the Resource Conservation and Recovery Act

understand the legal requirements of this provision (presented

in Section 2 of this guidance) and to provide technical

guidance that will aid owners or operators in complying with

the provision (presented in Section 3 of this guidance).
                              1-1

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                                         OSWER Policy Directive //9487.00-2A


                             SECTION  2
                      STATUTORY  REQUIREMENTS

BULK LIQUID HAZARDOUS WASTES PROHIBITED

    .Section  3004  (c)(l) calls  for an  absolute  ban after May  8,  1985,

on the placement of bulk or  non-containerized liquid hazardous

waste or free.liquids contained  in hazardous  waste in  any

landfill that  is subject to  regulation under  Subpart N of  40

CFR Parts 264  and  265.  The  intent of  the provision is to

prohibit the direct placement of bulk  liquid  hazardous wastes into

landfills, regardless of the presence  of liners or leachate

collection and removal systems.  The statute  makes it  clear

that the ban encompasses bulk hazardous waste containing

free liquids even  if.absorbents  have been added.

     The Agency interprets the ban on  "placement"  of bulk  liquid

hazardous wastes to include, but not be limited to: 1) placing

bulk liquid hazardous wastes into any  part of the  active

landfill unit where the liquids  are solidified and then

transferred to another part  of the active landfill unit,

and 2) placing treated bulk  liquid hazardous  wastes still  in

liquid form into a landfill  cell prior to solidification.

The legislative history of a related statutory provision,

section 3004(b) (banning the placement of liquid hazardous

waste in salt domes, underground mines, or caves)  supports the

view that Congress intended  the ban on "placement" to  be

construed broadly  to prohibit storage of material  while

awaiting further treatment or disposal, and to preclude use

of such locations as treatment chambers (129  Cong. Rec.

H8141 (daily ed. Oct. 6, 1983)).  Thus, the ban is effective

                              2-1

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regardless of the purpose of placing the liquids into a



landfill.



     In order to comply with this provision, the owner or operator



must determine whether a bulk hazardous waste (i.e., non-contain-



erized waste) is a liquid or contains free liquids.  EPA



regulations define "free liquids" as "liquids which readily



separate from the solid portion of a waste under ambient



temperature and pressure" (40 CFR Part 260.10).   Congress



anticipated that EPA would specify an appropriate test for



free liquids (see Senate Report No. 284, 98th Cong., 1st



Sess. 22 (1983)).  EPA believes that the Paint Filter Liquids



Test is the appropriate test method to be used to-determine



the absence or presence of free  liquids in both bulk and



containerized wastes.  On April 30, 1985, EPA promulgated



a final rule requiring the use of the Paint Filter Liquids Test



(Method 9095).   (See 50 FR 18370.)  This final rule requires



the owner or operator of a hazardous waste landfill to



use the Paint Filter Liquids Test to determine whether a



bulk hazardous waste is a liquid or contains free liquids,




if it is not obviously clear to the owner or operator that



the waste does or does not contain free liquids.  "Liquids"



and "free liquids" subject to this provision include liquids



that separate out during transportation to the landfill.



     If a sample passes the Paint Filter Liquids Test (i.e., no



liquid is detected), the bulk hazardous waste is not subject



to the ban in Section 3004 (c)(l) and can be landfilled



(assuming no absorbent has been added, as discussed below).






                              2-2

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If the sample fails the test, the bulk hazardous liquid



waste should be treated prior to landfilling using a treatment



technology that does not solely involve the use of a material that



functions primarily as an absorbent.  These treatment technologies,



include, chemical stabilization processes, and are discussed



under Treatment Technologies.  If, after reviewing a particular



stabilization process, it is not obvious that chemical stabilization



has taken place (i.e., if there are any concerns that "stabilization1



is occurring primarily due to the addition of sorbents),



then a representative sample of the treated waste should



pass the indirect chemical stabilization test (unconfined



compressive strength) as described under Test Method.  The



purpose of using a chemical stabilization test is to help



assure that the treatment of bulk liquids has been accomplished



in a manner that does not solely involve the use of a material



that functions primarily as an absorbent.



     Once it has been demonstrated, where necessary, that a



particular stabilization process used for a particular waste



will result in a treated product that passes the stabilization



test, then samples of each batch would only be required to



pass the Paint Filter Liquids Test prior to placement in the



landfill.  If there are any changes in the treatment process



and/or composition of the waste to be treated, stabilization



testing should be repeated.



USE OF ABSORBENTS



     A major issue raised by the language of Section 3004 (c)(l)



is the scope of the prohibition on absorbents.  The Agency





                              2-3

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is convinced that Congress did not want materials that function
solely as absorbents to be used in the treatment of bulk
liquid hazardous wastes that are to be placed in a landfill.
If Congress had intended to allow any or a certain subset of
"acceptable" absorbents to be used in the treatment of bulk
liguid hazardous wastes, Congress would have specified this,
as it did in the provision concerning the landfilling of
containerized hazardous wastes (see Section 3004(c)(2)).
     The Agency believes, however, that the term "absorbent" does
not include reagents used in: 1) any treatment technology
that involves no absorption and produces a bulk solid, or 2)
a treatment technology that chemically stabilizes, encapsulates,
or solidifies a bulk liquid hazardous waste.  EPA believes that
Congress was particularly concerned about the use of materials
that function solely as absorbents as a treatment method for
bulk liquid hazardous wastes in order to force the use of
other treatment methods (see Treatment Technologies for
preferred treatment methods) and because an absorbent may
release the absorbed liquid back to the environment.  (See 129 Cong.
Rec. H8141 (daily ed. Oct. 6, 1983)).  The legislative history
to this provision suggests that processes, such as chemical
stabilization, which, unlike absorption, render liquids
permanently unavailable to the environment, should be deemed
appropriate forms of pretreatment of liquid hazardous wastes
(129 Cong. Rec. H8141 (daily ed. Oct. 6, 1983)).  See also
130 Cong. Rec. S9177 (daily ed. July 25, 1984).  Consequently,
the Agency interprets the statute to permit the landfilling

                              2-4

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of bulk liquid hazardous wastes that have been chemically



treated and stabilized so as to contain no free liquids.



     If an absorbent material is used to clean up a spill of



hazardous waste, this mixture cannot be placed directly in a



landfill.  The reason, as stated before, is that the language



of the statute makes it clear that any liquid hazardous



waste, when contained and treated solely by the use of an



absorbent, is prohibited from being placed in a landfill in



a bulk or non-containerized form.  Congress did not specifically



exclude spills from the statutory prohibition.  If a spill



is treated solely by the use of absorbents, the absorbed



material may be containerized and placed in a landfill (subject




to any EPA regulation relating to absorbents in containers



under Section 3004(c)(2)), placed tn a surface impoundment,



or treated in a manner consistent with this guidance.



     Although spills treated with absorbents are subject to



the ban on landfilling of bulk liquid hazardous wastes to



which absorbents have been added, EPA believes that this ban



was not intended to encompass soils contaminated by accidental



spills into the ground.  The Agency believes, based on the



legislative history relating to absorbents, that Congress



was primarily concerned about controlling the use of absorbents



as a waste management method.  See 130 Cong. Rec. S9177



(daily ed. July 25, 1984).  There is no evidence that Congress'



concern extended to banning the placement in a landfill of



soils accidentally contaminated by spills of liquid hazardous



waste.  In consequence, contaminated soils will be subject





                              2-5

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to the same requirements as other hazardous wastes.  If the



contaminated soil passes the Paint Filter Liquids Test, it



will be allowed to be landfilled.  If, however, the contaminated



soil fails the Paint Filter Liquids Test, then the contaminated



soil must be subject to additional treatment as outlined in



this guidance.



LOCATION OF MIXING FACILITY



     The Agency also believes that in banning the placement of



bulk liquid hazardous wastes "whether or not absorbents have



been added," Congress intended to ban the placement in a



landfill of bulk liquid hazardous wastes that are treated



with materials that function solely as absorbents, whether



or not the treatment or mixing took place inside or outside



the landfill unit. ' Congress was concerned with the consequences



of placing the absorbed liquid wastes into the landfill unit



as well as with placing free liquids in the landfill.



     In some cases, the generator may have added an absorbent



to a bulk liquid hazardous waste.  As noted above, the statute



bans the placement in a landfill of bulk liquid hazardous wastes



if an absorbent was added to the waste regardless of where



the absorbent was added.  Therefore, EPA believes that an owner



or operator has the obligation to determine whether a generator



has added a material that functions solely as an absorbent to



a waste in order to eliminate free liquids.  Owners or operators



are not in compliance with the bulk liquids provision if they



place bulk liquid mixtures with absorbents in landfills.



     The Agency believes that responsibility for compliance





                              2-6

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with this provision rests solely with the landfill owner or



operator.  In developing this approach, the Agency also



considered whether responsibility for ensuring compliance



with the bulk liquids provision should be shared jointly by the



generator and the owner or operator.  For instance, if the



generators had treatment performed on the bulk liquids, the



generators would certify to landfill owners or operators that



no absorbents were used.  If no treatment was performed, they



would certify that no absorbent was added to the waste.  The



Agency rejected this approach because it was overly burdensome



to the generators.  As is currently practiced, the off-site



landfill owner or operator may enter into a private contractual



agreement with generators regarding the use of absorbents in



wastes to be landfilled.  A contractual agreement, however,



will not relieve the landfill owners or operators from their



responsibilities to ensure that absorbents were not used



in the treatment of the bulk liquids.
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                                        OSWER Policy Directive #9487.00-2A






                           SECTION  3



                           GUIDANCE



GENERAL GUIDANCE



     The goal of banning the placement  of bulk  liquid hazardous



wastes in landfills  is to reduce the migration  of  liquid



wastes and hazardous constituents.  To  this  end,  the preferred



methods for managing bulk liquid hazardous wastes  are:  1)



reduction in liquid waste generation by process design  changes



(e.g., using less liquid or recirculating rinse water)  and



by not mixing hazardous wastes with liquids, 2) recycling



and recovery (e.g., solvent extraction), 3)  treatment by



destruction (e.g., incineration), 4) treatment  to  render the



waste or liquid fraction nonhazardous,  5) treatment by  removing



liquids (e.g., decanting, centrifuge, vacuum drum  or conveyor,



filter press, distillation, reverse osmosis), and  6) treatment



by mixing with agents (e.g., chemical reagents  that remove



free liquids or chemically transform them into  solids).  [See



130 Cong. Rec. S9177 (daily ed.  July 25, 1984).]



     The owner or operator must use the Paint Filter Liquids Test



to determine if the bulk hazardous waste is  subject to  this



provision (i.e., the waste is a liquid or contains free



liquids).  If a hazardous waste fails the Paint Filter  Liquids



Test, it must be treated before landfilling  using  a treatment



technology that does not involve the use of  a material  that



functions solely as an absorbent.  If such treatment is considered



chemical stabilization, it may be necessary  for a  representa-



tive sample of the treated waste to pass the chemical





                              3-1

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                                      OSWER Policy Directive 09487.00-2A

stabilization test if it's not clear that stabilization
has occurred before the waste may be landfilled.  A bulk
liquid that has been treated with an absorbent may also be
landfilled in a container if it does not contain free-standing
liquids (40 CFR Parts 264.314 and 265.314), subject to any
                                      \
future EPA regulations relating to the use of absorbents in
containers.
     The Agency believes that the phrase "whether or not absorbents
have been added" requires that bulk liquid hazardous wastes
intended for disposal in a landfill should first be chemically,
thermally, physically, or biologically treated without the
use of absorbents.  Examples of these treatment technologies
were summarized above and are discussed further below.
Depending on the treatment technology selected, some bulk . .
liquid hazardous wastes will no longer be placed in landfills
while others will be converted to bulk solids that will then
be placed into the landfill.  The treatment methods listed below
are not meant to be all inclusive.  Some methods are listed because
they are alternatives to the placement of bulk liquid hazardous
wastes in landfills (i.e., not all the treatment methods are
directed toward the removal of liquids so that the bulk
hazardous liquid waste can be landfilled).  Of course, the
selection of the treatment method should comply with the
guidance of this provision.
     As stated above, the Agency will exclude from the definition of
"absorbent" reagents used in: 1) any treatment technology that
involves no absorption and produces a bulk solid, or 2) a

                              3-2

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treatment technology that chemically stabilizes, encapsulates,



or solidifies a bulk hazardous liquid. The definitions of



absorbent and chemical stabilization are presented in the



following sections.



     It is also important to remember that if the treatment of bulk



liquid hazardous wastes occurs in a tank, the treatment unit



may be subject to a RCRA permit.  If incineration is used,



this treatment is regulated under Part 264 or 265, Subpart



0.  It is also important to remember that the selected treatment



method (e.g., mixing) must not occur within the landfill



unit.



ABSORBENTS



     The Agency classifies an absorbent as a material that is



capable -of holding a liquid throughout the body of the absorbing



material.  In an absorbent, the liquid penetrates into the



inner structure of the absorbing material.  In many absorbents,



the volume of the absorbing material increases (i.e. swells)



as liquid is absorbed into the body of the absorbent.  The



use of a material that functions primarily as an absorbent



is prohibited as a means of treatment for bulk liquid hazardous



wastes if the absorbed mixture is to be placed in a landfill.



     The literature is confusing on the use of the terms absorbent



and adsorbent.  While absorption relies on liquid penetration



into the inner structure (i.e., within the void spaces between



solid particles) of the material, adsorption is a process



where the liquid or gas adheres to the surface of the adsorbing



material.  Adsorption is the result of intermolecular attractive





                              3-3

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forces between the adsorbent and the adsorbed gas or liquid.
The liquid is thus distributed over the surface of the adsorbing
material in a layer that is only one atom or molecule thick.
A material must have a high ratio of surface area to mass to
be an effective adsorbent.  The intermolecular forces of
attraction are normally weak, and the phenomenon is therefore
readily reversible.  In rare instances, however, a chemical
interaction between the adsorbent and the adsorbed substance
may occur.  In this process,  known as chemisorption, a
chemical reaction occurs resulting both in a molecular change
in the adsorbed material, and much stronger intermolecular
forces than are found with simple adsorption.  This process
is addressed later in this guidance.
     While the differences between absorption and adsorption
are easily defined on paper, it is much more dfficult to
determine whether a particular material acts as an absorbent
or adsorbent.  Standard test methods exist for determining
the holding power of materials, but these methods do not identify
the holding mechanism (i.e. absorption or adsorption).  In
reality, most materials are capable, to various extents of
holding materials by both mechanisms.
     In keeping with the intent of Congress, however, it is
not important to identify if absorption, adsorption, or both
are occurring, since neither process involves a chemical
transformation or encapsulation of the sorbed liquied (with
the exception of chemisorption).  Congress is concerned
about banning landfill disposal of liquid wastes that have
                              3-4

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not been treated in such a manner that they are permanently



unavailable to the environment.  Both absorption and adsorption



are reversible, and can release the sorbed material back



into the landfill. The Agency therefore interprets the ban



on "absorbents" to include materials that sorb wastes through



either absorption or adsorption.  Because of this interpretation



the Agency will simply consider adsorption and absorption



as physical processes and will thus refer to both as sortion



or sorbents.  Examples of banned sorbents include vermiculite,



Fuller's earth, bentonite, fine-grained sands, shredded



paper, and sawdust.  A sorbent material may, however, be



used as one of the ingredients in a chemical stabilization



process if the final product passes the unconfined compression



strength test discussed under the Test Method section, if it is  '"



necessary to use such a test.



     The use of a sorbent material will be considered an acceptable



treatment method for bulk hazardous liquid wastes under



appropriate conditions.  The owner or operator must first



demonstrate that the individual material irreversibly binds



a particular liquid waste through a chemical reaction (i.e.



chemisorption) rather than through the weak forces of absorption



or adsorption.  Chemisorption reactions are specific to the



chemical structure of both the sorbent and waste materials.



The owner or operator must therefore demonstrate that an



irreversible binding reaction has occurred for each particular



sorbent/waste combination.
                              3-5

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TREATMENT TECHNOLOGIES



Liquid-Solid Separation Processes



     Various liquid-solid separation processes are available to



separate the liquid and solid fractions of a bulk liquid



hazardous waste.  These include such operations as sedimentation



or decanting, flotation, filtration (including vacuum filtration),



centrifugation, evaporation, and distillation.  Sedimentation



or decanting is the removal of solid particles suspended in a



liquid by gravity settling.  Flotation involves the separation



of solids from liquids by the attachment of tiny air bubbles



to the solid particles.  The solid particles with the attached



air bubbles then rise to the surface of the liquid, agglomerate



there, and are skimmed off.  Filtration is the passage of



liquids through a fine mesh material that prevents the solid



material from passing.  Filtration can be enhanced by stirring



and by using vacuum or pressure rather than just gravity to



cause liquid flow.  Vacuum conveyors and drums can be used.



Centrifugation separates the solid and liquid components of



a waste stream by rapidly rotating the mixture in a vessel.



Evaporation is a physical separation process involving vaporization



of a liquid from a solution or a slurry.  Distillation is



evaporation of the more volatile component(s) within a mixture



with subsequent condensation to recover the evaporated liquid.



     Bulk liquid hazardous wastes can be subjected to such



liquid-solid separation processes, or a series of such processes



because some processes alone do not completely remove free



liquids.  The solid residuals can be isolated and then tested





                              3-6

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for the presence of free liquids using the Paint Filter

Liquids Test.  If the solids pass the test, they may be

placed into the landfill.  If they fail, additional liquid-solid

separation processes (or another form of treatment) would be

required to remove or eliminate the free liquids.  If the

liquid fraction isolated from the liquid-solid separation

process is a hazardous waste, it is subject to Section 3004(c)(l)

and should not be landfilled, unless one of the treatment

methods described below is employed.  Regardless of whether

the waste component is solid or liquid, it is still a hazardous

waste unless it is delisted, if it is a listed waste, or no

longer meets a characteristic of a hazardous waste.  The

characteristics of a hazardous waste are given in 40 CFR

Parts 261.21 - 261.24.

Biological Treatment

     Owners and operators may wish to consider other alternatives to

the treatment methods described above.  One alternative

could be biological treatment.  Biological treatment is a

generic term applied to processes that use living microorganisms

to decompose or detoxify organic wastes into either water,

carbon dioxide, non-toxic organics, non-toxic inorganics, or

acids and bases.  The principal types of conventional biological

treatment that might be useful for the treatment of bulk

liquid hazardous wastes are:

     o   activated sludge systems
     o   trickling filters
     o   aerated lagoons
     o   waste stabilization ponds

These treatment methods typically occur—in tanks or surface

                              3-7

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impoundments.  These hazardous waste units are subject to
regulation under Subparts J and K, respectively, of 40 CFR
Parts  264 and 265.
Thermal Treatment
     Another alternative is thermal treatment.  The treatment of
many non-aqueous bulk hazardous liquids  (e.g., solvents and
other  organics) can be achieved with high temperature destruction.
The goal of thermal destruction processes is the oxidation
of hazardous waste to water, carbon dioxide, aldehydes,
acids, etc.  Various thermal destruction methods can be
considered, such as:
     o   liquid injection incineration
     o   rotary kiln incinerators
     o   multiple hearth incinerators
Units used for such treatment are subjecJt to regulation under
Subpart 0 of 40 CFR Parts 264 and 265.
Chemical Treatment
     Chemical stabilization is a method that may be used to treat
bulk hazardous liquids prior to landfilling.  The majority
of the chemical stabilization techniques in use today: 1)
chemically react with the waste to transform free liquids
into solid or gel-like materials, 2) result in the production
of either a soil-like or clayey material, a thick sludge, a
monolithic block with high structural integrity, or a gel-like
material with high plasticity, and 3) have the additional
benefit of limiting one or more of the following: mobility,
solubility, and toxicity.  Stabilization usually involves
the addition of materials that ensures that the liquid portion
                              3-8

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 Df  the  waste  is  chemically  transformed  into  a  solid  and  that



 the  hazardous  constituents  are maintained  in their least



 soluble and/or least  toxic  form.   In  general,  higher quantities



 of  stabilization additives  result  in  a  more  solid product



 having  higher  strength  and  greater stability.



      Sorption  of a  liquid is  not the  same  as chemical stabilization.



 Sorption is a  physical  process that may often  be reversed,



 whereas stabilization involves a physical  and  chemical reaction



 between the liquids and waste constituents and the stabilizing



 reagents. •



      Examples  of the most commonly used stabilization technologies



 are  Portland  cement-based and pozzolanic processes.  The



 cement-based  process  is especially effective for wastes  with



'high levels of toxic metals,-because  at the  pH of the cement



 mixture,  most  multivalent cations  are precipitated as hydroxide



 or carbonate minerals of very low  solubility.  The Portland



 cement-based process  is also  effective  in  removing liquids



 because the reaction of the anhydrous cement powder  and



 water (liquids)  incorporates  the water  into  the solid mineral



 species.  The  reaction  first  produces a colloidal calcium-silicate-



 hydrate gel of indefinite composition and  structure.  Hardening



 of the  cement  is brought about by  the interlacing of thin,



 densely-packed,  silicate fibrils growing from  the individual



 cement  particles.



      Waste stabilization techniques based  on lime products (as



 opposed to Portland cement) usually depend on  the reaction



 of lime with  a fine-grained siliceous (pozzolanic) material



                              3-9

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and water to produce a solid that is sometimes referred to
as pozzolanic cement. The most common pozzolanic materials
used in waste treatment are fly ash, ground blast-furnace
slag, and cement kiln dust.
     The stabilized waste product from both cement-based and
pozzolanic processes can vary in consitency from a weak
soil-like or clay-like material a hard, concrete-like mass.
The consistency depends on a variety of factors including
waste type, moisture content, organic content, and the type
and amount of stabilization additives used.
     These chemical stabilization techniques require a thorough
knowledge of the chemistry of the wastes and treatment reagents.
In many cases, special proprietary reagents (usually polymers)
are added.  This is often required to control the adverse
effects of organic compounds on the cementation process.
Cement and pozzolanic stabilization may be ineffective in
treating many organic compounds.  The treatment must be
conducted in a well-controlled procedure that employs sophisticated
quality control/quality assurance methods.  This treatment
typically occurs within specially designed vessels, using
special apparatus to control the addition and blending of
reagents.  The units in which these processes occur are
typically classified as tanks; these would generally be
subject to regulation under Subpart J of 40 CFR Parts 264
and 265.  These tanks could be situated in the landfill
provided that both the tank and the landfill are regulated
in accordance with applicable standards.
                              3-10

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TEST METHOD



     Because  it  is often difficult to determine whether a particular



process involves stabilization, or is merely absorption, EPA



expects owners and operators using a chemical stabilization



process to demonstrate that the chemical transformations



described above occur. Laboratory data showing that an appropriate



"recipe" has  been developed and used, plus a demonstration



that stabilization has occurred may be necessary in cases where



there is a question of whether a particular process actually



involves stabilization"rather than sorption.  Descriptions



of the treatment apparatus and quality control methods should



als'o be available, and provided with permit applications.



     To aid owners or operators in demonstrating that chemical



stabilization -has occurred, the Agency 'is recommending a



testing scheme as shown in Exhibit 1.  Under this method, any



bulk hazardous waste  (i.e., no sorbents added) that may contain



free liquids  is subject to the Paint Filter Liquids Test.



If the waste  passes the test, it is not subject to the ban



(i.e. it can  be disposed in a landfill).  If the waste fails



the test, it  may then be treated by a chemical stabilization



process prior to landfill disposal. (NOTE: It may be determined



that one of the other waste treatment methods described in



Treatment Technologies is preferred.)  If the waste is treated



using a chemical stabilization process, and if it is not



obvious that  true chemical stabilization has occurred (i.e.,



if it is suspected that a material that functions solely



as a sorbent  has been used), then a representative sample of





                              3-11

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                        I
                            BULK
                            HAZARDOUS
                            WASTE
Paint Filter
Liquids Test
Pass (no free Liquids!
(Provided no sorbents
have been added)
Landfill
Disposal
                              Fail  (Contains Free Liquids)
                Chemical  Stabilization
                       Process
                                  I
Confirmation of
CheraiC'.  Stabiliza-
tion by State or
Regions based on data
Supplied
        Unconfined Compressive
           Strength Test
          50 psi Minimum
Fail1
         Pass
            Pass
Fail
                            Landfill
                            Disposal
                          Alternative
                          Treatment
                             EXHIBIT 1

                    Bulk Liquid Testing Procedures
                              3-12

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the waste should then pass the chemical stabilization test



before it can be disposed in a landfill.  ,



     Once it has been demonstrated that a particular process used



for a particular waste will result in a treated product that



passes the stabilization test, then samples of each batch



would only be required to pass the Paint Filter Liquids Test



prior to placement in the landfill.  If there are any changes



in the treatment process and/or composition of the waste to



be treated, stabilization testing should  be repeated.



     A wide range of tests were consider for determining if chemical



stabilization has occurred.  Tests exist that determine



whether or not a chemical reaction has taken place.  However,



these tests are specific to the reacting materials.  The



wide range of wastes and treatment processes results in an



essentially unmanagable number of these confirmatory tests



for chemical reactions.



     Rather than proposing a series of chemical analyses tests,



it is desired to have a single test method that can be used



for all types of wastes.  The unconfined compressive strength



test is proposed as an indirect method for determining the



stability of treated waste products.  If the owner or operator



wishes to use a different method to show that chemical stabilization



rather than sorption has occurred, this information should



be provided with the facility's Waste Management Plan (for



Interim Status Units) or the hazardous waste permit application.



     As previously discussed, chemical treatment methods that



solidify liquid wastes typically result in either cemented





                              3-13

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masses comparable to concrete or discrete particles and low



strength mixtures such as sand, soil, weak clay, or sawdust.



The most common of these processes are cement-based and



pozzolanic processes.  It is known that these reactions



produce a product having greater strength than the original



materials. Compressive strength can therefore be used as



an indirect measure of the extent of chemical stabilization



when these methods are used to treat liquid wastes.



     It is highly desirable to have a single compression test



that could be used for most of these stabilized wastes,



regardless of the specific waste type or stabilization process



used.  It is also desired that the test be performed with



unconfined samples.  Unconfined tests can be performed only



on cohesive materials.  Since the addition of sorbents generally



results in a non-cohesive product, the use of the unconfined



test will help assure that wastes treated solely by sorbents



are not placed in the landfill.



     The unconfined compressive strength test should be modeled on



ASTM D2166-85, Unconfined Compressive Strength of Cohesive



Soil.  The selection of the unconfined compressive strength



test, based on soil testing methodology, is aimed at the



cemented or pozzolanic class, but is very applicable to the



stiffer, less ductile plastics.  A minimum allowable strength



is selected as the measure of adequate bonding.  The minimum



strength recommended is 50 psi.  The rationale for selecting



this value is an effort to require a bonding level in excess



of that achieved with sorbents.  The electrostatic and surface





                              3-14

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tension bonding that is present in most of these materials



is most strongly present in very stiff clays.  For comparative



purposes, the compressive strengths of a variety of materials



are shown in Exhibit 2.  As shown in Exhibit 2, very stiff



clays typically have unconfined compressive strengths of 28



to 57 psi.  It is felt that a compressive strength limit



nearer the high end of this range will assure that chemical



bonding, and not just absorption or adsortion, is present.



The 50 psi minimum compressive strength limit should also



assure that the1treated waste has at least as much strength



as the soil surrounding the disposal site.



     The second common class of products resulting from stabilization




processes are the low strength soil-like and clay-like materials,



including cohesionless sandy products.  If it is.not apparent that



the process is indeed "stabilization" then it would be necessary



to use the unconfined compressive strength test.  However,



further treatment may be necessary to achieve the 50 psi limit,



however, the amount of treatment is expected to be minimal.



     In an attempt to predict how easily various types of soils or



soil-like wastes could be treated to increase their unconfined



compressive strengths, the results of a series of soil-stabilization



studies are presented [8].  These studies were performed



using nine different soil types.  Prior to the addition of



stabilization compounds, test specimens were molded according



to ASTM D1632-63: Standard Method of Making and Curing Soil-Cement



Compression and Flexure Test Speciments in the Laboratory.



After seven days of controlled storage, the unconfined compressive





                              3-15

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EXHIBIT 2.   OPPRESSIVE STRENGTH DATA (PSI)
Material
BRICK
Grade SW
Grade MW
Grade NU
CERAMICS, GLASS, CARSON
Alumina Ceramics
Carbon, Coal based
Carbon, Petroleum based
Industrial Graphite
Polycrystal line Glass
Porcelain
Stoneware
Tungsten Carbide
CLAY (UNCONFINED)
Very Soft
Soft
Medium
Stiff
Very Stiff
Extremely Stiff
CONCRETE
Low Strength
Medium Strength
High Strength
METALS
Cast Iron, grey
PLASTICS AND ELASTOMERS
Acrylics, cast
Cellulose Acetate, molded
Epoxy, amine
Epoxy, general purpose
Epoxy, poly amide
Nylons
Phenolics, cast, type 1
Phenol ics, molded, general purpose
Polyester, cast, rigid
Polyester, cast, flexible
Polypropylene
Polystyrene, general purpose
Polytetraf luoroethylene (Teflon)
Si 1 icone, cast, type 1
STONE
Grani te
Limestone
Marble
Sandstone
Slate
Compressive Strength

3,000
2,500
1,500

350,000
1,700-2,400
6,300-9,000
1,900-8,500
50,000
60,000-90,000
40,000-80,000
600,000

Less than 3.6
3.6 to 7.1
7.1 to 14
14 to 28
28 to 57
Over 57

2,000
3,000-4,000
5,000

120,000

12,000-18,000
20,000
4,000
30,000
6,000
2,400-9,700
14,000-18,000
30,000
12,000-37,000
1,000-17,000
5,500-6,500
14,000
700-1,800
14,000-18,000

13,000-55,000
2,500-28,000
8,000-27,000
5,000-20,000
9,000-10,000
Reference

1
1
1

2
3
3
3
3
4
4
2

5
5
5
5
5
5

2
2
2

6

7
2
4
2
4
3
7
2
3
3
3
2
3
7

1
1
1
1
1
                    3-16

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strength of each soil type was measured according to ASTM



D1633-63: Test for Corapressive Strength of Molded Soil-Cement



Cylinders.  The results, shown in Exhibit 3, indicate strengths



ranging from 26 to 56 psi.  All values in Exhibit 3 are the



average of three specimens.



     Samples of each of the nine soil types were then mixed with



simple stabilization compounds.  Two different stabilization



additives, cement and lime, were used for each soil type.



The cement additive consisted of a blend of three brands.



The lime consisted of a blend of two brands.  For each additive,



two different quantities, 3 percent and 5 percent, were



used, resulting in four different mixtures for each soil




type.



     Specimens were prepared in accordance with ASTM D1632.  Specimens



were molded either immediately after machine mixing of the



soil/additive blend (denoted as no compaction in Exhibit 3)



or after a 24-hour delay.  During the delay, the material



was stored at 73 degrees F.  Any moisture lost during the



delay was replaced.  The materials were remixed prior to



molding.



     The results of the unconfined compressive strength tests for



both the no-delay and 24-hour delay specimens appear in



Exhibit 3.  Final strength increase, as measured against the



strength of the untreated soils, ranges from 56 percent to



1,800 percent.  It is especially important to note that



small additions of either cement or lime yieldec dramatic



increases in compressive strength of soils.  Increases of





                              3-17

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                    EXHIBIT 3. UNCONFINED COMPRESSIVE STRENGTHS  (PSD
Soi I
Number Additive
1 None
3X Cement
3% Lime
5X Cement
5X Lime
2 None
3% Cement
3/1 Lime
5X Cement
5X Lime
3 None
3% Cement
3X Lime
5X Cement
5X Lime
4 None
. 3% Cement
3X Lime
5X Cement
5% Lime
5 None
3X Cement
3X Lime
5X Cement
SX Lime
6 None
3X Cement
3X Lime
5X Cement
5X Lime
7 None
3X Cement
3X Lime
5X Cement
5X Lime
8 None
3X Cement
3X Lime
5X Cement
5% Lime
9 None
3% Cement
3X Lime
5% Cement
5% Lime
No
7-day
Strength
56
98
76
160
120
26
316
80
445
103
29
216
89
332
115
23
210
64
323
111
41
124
78
172
95
26
234
116
405
137
37
158
149
243
172
54
114
98
174
111
38
147
131
237
175
Compact i on
28-day
Strength
..
135
128
233
190
, .
374
136
495
161

277
153
426
174

269
117
414
171

149
97
232
164

276
184
452
204
202
184
310
260

158
150
234
216

186
234
377
292
Delay
90 -day
Strength
. .
189
155
311
274




• •




• •







* -
• •




• *
::


• •

254
218
379
313

240
270
466
369
24-Hr. Compact
7-day
Strength

83
86
V35
132

243
75
270
84

179
95
256
121
.
141
58
234
98

100
81
158
93

156
88
217
101
135
174
219
198

84
103
141
145

107
118
204
202
ion Delay
28-day
Strength

128
143
207
193

324
117
371
138
•-
238
146
320
192

185
103
302
184

133
114
213
175

267
166
346
193
192
221
283
292

140
143
205
252

137
166
294
322
Source:  C 3 3



»U  compressive strengths are the averse of three species.
                                                3-18

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two-fold to fourteen-fold resulted from the addition of only



3 percent cement.  The unconfined compressive strengths of



the soils treated with lime also appear in Exhibit 3.  These



strengths range from 76 psi to 369 psi.  The strength increase,



as measured against the strength of the untreated soils,



ranges from 36 percent to 870 percent.  Again, it is important



to note that the addition of only 3 percent or 5 percent



lime results in a dramatic increase in the unconfined compressive



strength.



     These studies show 'that the recommended 50 psi unconfined



compressive strength limit is easily attainable for soil-like



products.  The addition of minimal amounts of cement or lime



can be used.  All of the soils treated with 3 percent cement



exceeded the 50 psi criteria within 7 days.— All of"the



soils treated with 3 percent lime also reached the criteria



within the 7 days.   The compressive strengths of all of



the tested soils were even greater after 28 days.  Changes



in product strength as a function time are further discussed in



the following section.



TIME FACTOR



     The Agency knows that time is necessary for complete and



final chemical stabilization to occur.  This time has been



stated to be from several hours to 7 days or more, depending



on the waste type and treatment process used.  As noted



earlier, EPA interprets the statutory language as banning the



placement of treated  bulk liquid hazardous wastes in a



landfill prior to the treated material passing the Paint





                              3-19

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Filter Liquids Test.  Unconfined Compressive strength testing,



when necessary, should be performed in advance for each



waste to be treated by a  particular  process.  This preliminary



testing will identify the acceptable cure times required for



a stabilized waste to meet the 50 psi limit.



     This guidance does not contain a list of acceptable



stabilization materials because a material may be both a



sorbent and an ingredient in a stabilization process.



General technical reference information on chemical stabilization



methods is available in the Guide to the Disposal of Chemically



Stabilized and Solidified Waste (EPA, 1982).  This is available



from the  U.S. Government Printing Office, Washington, D.C.



20401 under stock number 055-000-00226-6, for $6.00.



IMPLEMENTATION                    __



     Process changes at some facilities with hazardous waste



landfills may be necessary in order to comply with this



statutory prohibition.  These process changes may be in the



form of additional storage or treatment units.  Section



270.72 allows changes in the processes for the treatment or



storage of hazardous waste at the facility or the addition



of other units if the owner or operator submits a revised



Part A permit application to EPA (or an authorized State)



prior to such a change along with justification explaining



the need for the change and the Regional Administrator (or



the Director of the State agency in an authorized State)



approves such a change.  The Regional Administrator (or the



Director of the State agency in an authorized State) may



                              3-20

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                                       OSWER Policy Directive //9A87.00-2A


approve such changes because they will be necessary to comply

with this new statutory requirement.

REFERENCES

1.   Baumeister, T., E.A. Avallone, and T. Baumeister III, Editors,
          Marks' Standard Handbook for Mechanical Engineers,
          Eighth Edition, McGraw-Hill Book Company, New
          York, 1978, pp. 6-149 to 6-159.

2.   Richards, C.W., Engineering Materials Science, Wadsworth Publishing
          Company,  Inc., Belmont, California,  1961, pp.  518-521.

3.   Materials Selector 76, Materials Engineering Magazine, 82(4),
          Mid-September, 1976.

4.   Perry, R.H. and D.W. green, Editors, Chemical Engineers'
          Handbook, Sixth Edition, McGraw-Hill Book Company,
          New York, 1984, pp. 23-58 to 23-62.

5.   Terzaghi, K.,  and R.B., Peck, Soil Mechanics in Engineering
          Practice, John Wiley and Sons, New York, 1948, p. 31.

6.   Popov, E.P., Mechanics of Materials, Second Edition,
          Prentice  Hall, Inc., Englewood Cliffs, New Jersey,
          1976, page 570.

7.   Perry, R.H., and C.H. Chilton, Editors, Chemical Engineers'
          Handbook, Fifth Edition, McGraw-Hill Book Company,
          New York, 1973, pp. 23-62.

8.   Christensen, A.P., Cement Modification of Clay Soils,
          Portland  Cement Association, 1969.
                              3-21

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