United States       Solid Waste and
 Environmental Protection  Emergency Response  EPA530-F-94-018
 Agency          (5305)         May 1994
RCRA Policy Statement
Clarification of the Land
Disposal Restrictions'
Dilution Prohibition and the
Combustion of Inorganic
Metal-bearing Hazardous
       7"^. ~\S Printed on paper that contains at
        \ZJvI7 least 50% post-consumer recycled fiber

NOTE:      This document is intended to be an information resource.  It may contain
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                         WASHINGTON, D.C. 20460
                          MAT 23199*
                                                        OFFICE OF
                                              SOLID WASTE AND EMERGENCY RESPONSE

          RCRA Policy  Statement:   Clarification of the Land
          Disposal Restrictions1  Dilution Prohibition and
          Combustion of  Inorganio«Metal-Bearing Hazardous Wastes
                                                          I - X
PROM:     Elliott P.  Law
          Assistant Admin

TO:       Waste Management Division Directors, Regions

I.   introduction

A.   Purpose
     This memorandum sets out a Statement of Policy under th*
Resource Conservation and Recovery Act  (RCRA) clarifying the
application of the Land Disposal Restrictions ^(LDR)  prohibition
on  dilution (see 40 CFR S 268.3) to combustion  of certain
inorganic metal-bearing hazardous wastes.  Because  combustion
normally does not represent effective treatment of  these wastes,
such burning can be considered impermissible dilution.   In such
cases,  these hazardous metal-bearing wastes cannot  be combusted
legally.  This Policy Statement clarifies the general situation
regarding combustion of these metal-bearing hazardous wastes, but
application of this policy will vary depending on particular

B.   Regulatory Background

     Under RCRA, the LDR prohibition on dilution  states generally
that no parson "shall in any way dilute a restricted waste ... as
a substitute for adequate treatment to  achieve compliance with [a
treatment jacandard for that waste]".  40 CFR 268.3(a).   This
prohibitidllf iMplements the requirement  of section 3004 (m) of
RCRA,  whicfc- r«Kjuir«8 that hazardous constituents  in hazardous
wastes be destroyed, removed or immobilized before  these wastes
 can be land disposed.  Hazardous constituents are not destroyed,
 removed or  immobilized if they are diluted.  Chemical Waste
 Management v. EPA. 976 F.2d 2,  16, 17,  19-20  (D.C.  Cir. 1992),
     1      Combustion for purpose* of this memo does not include tMtal
 recovery unit» engaged in metal reclamation or vitrification units engaged in
 metal stabilization.
                                                          Print* on Recycled Paper

cert, denied 113 S.Ct.  1961  (1993);  see also S.  Rep. No. 298,
98th Cong. 1st Sess.  17  (1983)  ("the dilution of wastes by the
addition of- other hazardous  waste or any other materials during
waste handling, transportation,  treatment or storage is not an
acceptable method of  treatment  to reduce the concentration of
hazardous constituents").

     Consistent with  these authorities,  the Agency has stated
that the dilution prohibition serves one chief purpose— "to
ensure that prohibited wastes  are treated  by methods  that  are
appropriate for that  type of waste."  55 FR at 22532 (June 1,
1990).  Impermissible dilution  can occur under a number of
circumstances.  The most obvious is  when solid wastes are added
to a prohibited waste to reduce concentrations but not volumes of
hazardous constituents,  or to mask their presence.  Impermissible
dilution also may occur  when wastes  not amenable to treatment by
a certain method  (i.e.,  treated very ineffectively by that
treatment method) are nevertheless 'treated1 by that method.   55'
ER 22666  (June 1, 1990)  (biological  treatment does not
effectively remove toxic metals from wastes; therefore,
prohibited wastes with .treatment standards for metals ordinarily
would be impermissibly  diluted  if managed in biological treatment
systems providing no  separate treatment for the metals).  See
also 52 FR at 25778-79  (July 8,  1987)  (impoundments which
primarily evaporate hazardous constituents do not qualify as
section 3005(j)(11) impoundments which may receive otherwise-
prohibited hazardous  wastes  that have not met the treatment

     EPA  is providing guidance  today clarifying how the LDR
dilution prohibition  could apply to  certain inorganic metal-
bearing hazardous wastes that may be placed in combustion units,
other than metal  recovery furnaces.
General Distinction Between "Adequate Treatment" and
Potential Violations of the Dilution Prohibition
      This memorandum deals with the question of whether
 combustion of prohibited inorganic hazardous wastes can be a type
 of  impermissible dilution.  An "inorganic hazardous waste" is one
 for which EPA has established treatment standards for metal
 hazardous constituents,  and which does not otherwise contain
 significant organic or,cyanide content (see further discussion,
 last paragraph page 3,  clarifying what constitutes an
 insignificant organic or cyanide content).
     *      A "prohibited" hazardous waate La one which La actually subject to
 a prohibition on land disposal without first being treated, or disposed in a
 no-migration unit.  See 54 FR 36968 (Sept. 6, 1989).

     The Agency has  evaluated the listed wastes and has
determined that 44 of  the  RCRA listed wastes (as set forth in 40
CFR § 261)'typically appear to be such inorganic hazardous
wastes; i.e., they typically do not contain organics, or contain
only insignificant amounts of organics,  and are not regulated for
organics  (see Appendix A to  this memorandum for a  list of these
wastes).  The Best Demonstrated Available Technology (BOAT) for
these inorganic, metal-bearing listed wastes is metal recovery or
stabilization.  Thus,  impermissible dilution may result when
these wastes are combusted.

     There are eight characteristic metal waste codes; however,
only wastes that exhibit both the toxicity characteristic (TC)
and the extraction procedure (EP)  for D004 - D011 are prohibited
now (see 55 FR 22660-02, June 1,  1990).   Characteristic wastes,
of course, cannot be generically characterized as easily as
listed wastes because  they can be generated from many different .
types of processes.  For example,  although some characteristic
metal wastes do not  contain organics or cyanide or contain only
insignificant amounts,  others may have organics or cyanide
present which justify  combustion,  such as a used oil exhibiting
the TC  characteristic  for  a metal.   Thus, it is difficult to say
which D004-D011 wastes would be impermissibly diluted when
combusted, beyond stating  that as a general matter, impermissible
dilution would occur if the DO04-DO11 waste does not have
significant organic  or cyanide content but is nevertheless

     EPA ordinarily  would  not consider the following hazardous
wastes  to  be strictly  inorganic (or to contain "significant
organic or cyanide content")  for which combustion would otherwise
be impermissible dilution.   Combustion of the following wastes is
therefore  not prohibited under the LDR dilution prohibition:   (1)
any of  the 44 listed wastes and 8 characteristic wastes in
Appendix A that, at  point  of generation, or after any bona fide
treatment  such as cyanide  destruction prior to combustion,
contain hazardous organic  constituents or cyanide at levels
exceeding  the constituent-specific treatment standard for F039,
which represents a compilation of numerical limits for hazardous
constituents;  (2) organic,  debris-like materials (e.g., wood,
paper,  plastic, or cloth)  contaminated with an inorganic metal-
bearing hazardous waste; and (3)  any of the 44 listed wastes and
8 characteristic wastes that, at point of generation, have
reasonable heating value such as greater than or equal to 5000
Btu  (see  48  FR  11157 (March 16, 1983)).   The foregoing three
categories of waste  typically would contain sufficient organic
     3      To the extent that these wastes or residues of these wastes (i.e.,
 biological treatment sludges) contain significant organic content, combustion
 may be an appropriate treatment technology. See later discussion regarding
 this point.                         '

content to indicate that combustion can be a reasonable means of
treating the wastes prior to land disposal.  However, as noted
above, mixing practices such as fuel blending to add organics to
inorganic i&etal-bearing hazardous wastes ordinarily would be
considered to be impermissible dilution.  This is because the
dilution prohibition applies at the point a hazardous waste is
generated.  Chemical Waste Management v. EPA. 976 F.2d at 22-3;
also 48 FR 11158, 11159 and nn. 2 and 4  (March 16, 1983); 53 FR
at 522  (Jan. 8, 1988)  (determinations of legitimacy of recycling
are made on a waste-by-waste basis before any blending occurs).

     This Policy Statement is also reflective of the Agency's
concerns about the hazard presented by toxic metals in the
environment.  When an  inorganic metal-bearing hazardous waste
with insignificant organics is placed in a combustion unit,
legitimate treatment for purposes of LDR ordinarily is not
occurring.  No treatment of the inorganic component occurs during
combustion, and therefore, metals are not destroyed, removed, or
immobilized.  Since there are no significant concentrations of
organic compounds in inorganic metal-bearing hazardous wastes, it
cannot be maintained that the waste is being properly or
effectively treated via combustion  (i.e., thermally treated or
destroyed, removed, or immobilized).

     In terms of the dilution prohibition, if combustion is
allowed as a method to achieve a treatment standard for these
wastes, metals in these wastes will be dispersed to the ambient
air and will be diluted by being mixed in with combustion ash1
from other waste streams.  Adequate treatment  (stabilization or
metal recovery to meet LDR treatment standards) has not been
performed and dilution has occurred.  It is also inappropriate to
regard  eventual stabilizing of such combustion ash as providing
adequate treatment for purposes of the LDRs.  Simply meeting the
numerical BOAT standards  for the ash fails to account for metals
in the  original waste  stream that were emitted to the air and for
reductions achieved by dilution with other materials in the ash.
 (In most cases, of course, the metal-bearing wastes will have
been mixed with other  wastes before combustion, which mixing
itself  could be viewed as impermissible  dilution).

      These  inorganic,  metal-bearing hazardous wastes should be
and are usually treated  by metal recovery or stabilization
technologies-.  These technologies remove hazardous constituents
through recovery  in products, or immobilize them, and are
therefore permissible  BOAT treatment methods.  However, EPA
believes  that  this statement  of policy clarifying application of
LDR dilution prohibition is needed  because we have observed that
 some  of these  wastes may be going to conventional combustion
devices such as  incinerators  or cement kilns.  For example, some
 owners/operators  may be  willing to  accept  inorganic  lead wastes
with insignificant organics  at their combustion  facilities  (which
 can still apparently meet their air emissions  limits at the

stack).  As explained above, land disposal of  combustion
residuals from these facilities would typically violate the  land
disposal restrictions prohibition on dilution.  Combustion is not
usually an appropriate treatment for these wastes because
hazardous constituents are not removed, destroyed, or

      Consequently, the general principles set out in this
memorandum, subject to appropriate consideration of individual
circumstances, are:  (l) that a prohibited inorganic metal-
containing hazardous waste (listed in Appendix A to this
memorandum) without significant organic content can be considered
to be diluted impermissibly when combusted (even if the treatment
standards for metals are achieved in part by subsequent treatment
of combustion ash); and (2) that the determination of whether a
waste is an inorganic metal-bearing hazardous waste is made at
the point of generation .   This means  that, ordinarily,  such  a
waste would be considered to be diluted impermissibly even if it
is blended with organic wastes for which combustion would
otherwise be an appropriate treatment method.
          This is the point at which the waste becomes hazardous.
(See 45 FR 33095-33096, May 19, 1980).

I Waste Cod*
1 F006 5*
1 F007 *
1 F008 *
F009 *
1 F010 *
F011 *
1 F012 *
I F019 *
Listed Wastes
Wastewater treatment sludges from electroplating
operations except from the following processes:
(1) sulfuric acid anodizing of aluminum; (2) tin
plating carbon steel; (3) zinc plating
(segregated basis) on carbon steel; (4) aluminum
or zinc-plating on carbon steel; (5)
cleaning/ stripping associated with tin, zinc and
aluminum plating on carbon steel; and (6)
chemical etching and milling of aluminum.
Spent cyanide plating bath solutions from
electroplating operations .
Plating bath residues from the bottom of plating
baths from electroplating operations where
cyanides are used in the process.
Spent stripping and cleaning bath solutions from
electroplating operations where cyanides are
used in the process.
Quenching bath residues from oil baths from
metal treating operations where cyanides are
used in the process.
Spent cyanide solutions from salt bath pot
cleaning from metal heat treating operations.
Quenching waste water treatment sludges from
metal heat treating operations where cyanides
are used in the process.
Wastewater treatment sludges from the chemical
conversion coating of aluminum except from
zirconium phosphating in aluminum car washing
when such phosphating is an exclusive conversion
coating process. 	 	 	
Wastewater treatment sludge from the production
of chrome yellow and orange pigments.
Wastewater treatment sludge from the production
of molybdate orange pigments.
                         Assuming wastes do not contain treatable
                         concentrations .of cyanide.

Waste Code
Listed Wastes
Wastewater treatment sludge from the production
of zinc yellow pigments.
Wastewater treatment sludge from the production
of chrome green pigments.
Wastewater treatment sludge from the production
of chrome oxide green pigments (anhydrous and
hydrated) .
Wastewater treatment sludge from the production
of iron blue pigments.
Oven residue from the production of chrome oxide
green pigments.
Emission control dust/sludge from the primary
production of steel in electric furnaces.
Emission control dust/sludge from secondary lead
Brine purification muds from the mercury cell
processes in chlorine production, where
separately prepurified brine is not used.
Waste leaching solution from acid leaching of
emission control dust/sludge from secondary lead
Sludges from the mercury cell processes for
making chlorine.

P013 *
P029 *
P074 *
P104 *
Arsenic acid H,AsOA
Arsenic oxide As,O,
Arsenic trioxide
Barium cyanide
Copper cyanide Cu(CN)
Nickel cyanide Ni(CN),
Osmium tetroxide
Potassium silver cyanide
Silver cyanide

Waste Cod*
P121 *
Listed Wastes
Thallic oxide
Thallium (1) selenite
Thallium (1) sulfate
Ammonium vanadate
Vanadium oxide V,O,
Zinc cyanide
Zinc phosphide


Calcium chromate
Lead phosphate
Selenious acid
Selenium disulfide
Thallium (I) chloride
Thallium (I) nitrate
Waste Code
Characteristic Wastes