[Federal Register Volume 65, Number 179 (Thursday, September 14, 2000)]
[Proposed Rules]
[Pages 55684-55782]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-22810]



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Part II





Environmental Protection Agency





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40 CFR Part 148 et al.



Hazardous Waste Management System; Identification and Listing of 
Hazardous Waste: Inorganic Chemical Manufacturing Wastes; Land Disposal 
Restrictions for Newly Identified Wastes; and CERCLA Hazardous 
Substance Designation and Reportable Quantities; Proposed Rule

  Federal Register / Vol. 65, No. 179 / Thursday, September 14, 2000 / 
Proposed Rules  

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 148, 261, 268, 271, and 302

[SWH-FRL-6864-5]
RIN 2050-AE49


Hazardous Waste Management System; Identification and Listing of 
Hazardous Waste: Inorganic Chemical Manufacturing Wastes; Land Disposal 
Restrictions for Newly Identified Wastes; and CERCLA Hazardous 
Substance Designation and Reportable Quantities

AGENCY: Environmental Protection Agency.

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) proposes to amend 
the regulations for hazardous waste management under the Resource 
Conservation and Recovery Act (RCRA) by listing as hazardous three 
wastes generated from inorganic chemical manufacturing processes. We 
also propose not to list as hazardous various other process wastes. 
This action proposes to add the toxic constituents found in the wastes 
to the list of constituents that serves as the basis for classifying 
wastes as hazardous, and to establish treatment standards for the 
wastes.
    The effect of this proposed regulation would be to subject the 
wastes to stringent management and treatment standards under Subtitle C 
of RCRA. Additionally, this action proposes to designate the wastes 
proposed for listing as hazardous substances subject to the 
Comprehensive Environmental Response, Compensation, and Liability Act 
(CERCLA) and to adjust the one-pound statutory reportable quantities 
(RQs) for some of these substances.

DATES: EPA will accept public comments on this proposed rule until 
November 13, 2000. Comments postmarked after this date will be marked 
``late'' and may not be considered. Any person may request a public 
hearing on this proposal by filing a request with Mr. David Bussard by 
September 28, 2000.

ADDRESSES: If you wish to comment on this proposed rule, you must send 
an original and two copies of the comments referencing docket number F-
2000-ICMP-FFFFF to: RCRA Information Center, Office of Solid Waste 
(5305G), U.S. Environmental Protection Agency Headquarters, 1200 
Pennsylvania Avenue, NW, Washington, D.C. 20460. Hand deliveries of 
comments should be made to RCRA Information Center, Crystal Gateway I, 
First Floor, 1235 Jefferson Davis Highway, Arlington, VA.
    You also may submit comments electronically by sending electronic 
mail through the Internet to: [email protected]. You should 
identify comments in electronic format with the docket number F-2000-
ICMP-FFFFF. You must submit all electronic comments as an ASCII (text) 
file, avoiding the use of special characters and any form of 
encryption.
    Address requests for a hearing to Mr. David Bussard at: Office of 
Solid Waste, Hazardous Waste Identification Division (5304W), U.S. 
Environmental Protection Agency, 1200 Pennsylvania Avenue, NW, 
Washington, D.C. 20460, (703) 308-8880.

FOR FURTHER INFORMATION CONTACT: For general information, contact the 
RCRA/Superfund Hotline at (800) 424-9346 or TDD (800) 553-7672 (hearing 
impaired). In the Washington, D.C., metropolitan area, call (703) 920-
9810 or TDD (703) 412-3323. For specific aspects of the rule, contact 
Ms. Gwen DiPietro, Office of Solid Waste (5304W), U.S. Environmental 
Protection Agency, 1200 Pennsylvania Avenue, NW, Washington, D.C., 
20460. [E-mail addressee and telephone number: [email protected] 
(703-308-8285).] For technical information on the CERCLA aspects of 
this rule, contact Ms. Lynn Beasley, Office of Emergency and Remedial 
Response, Analytical Operations and Data Quality Center (5204G), U.S. 
Environmental Protection Agency, 1200 Pennsylvania Avenue, NW, 
Washington, D.C. 20460, [E-mail address and telephone number: 
[email protected] (703-603-9086).]

SUPPLEMENTARY INFORMATION: If you do not submit comments 
electronically, we ask you to voluntarily submit one additional copy of 
your comments on labeled personal computer diskettes in ASCII (text) 
format or a word processing format that can be converted to ASCII 
(text). It is essential to specify on the disk label the word 
processing software and version/edition as well as your name. This will 
allow us to convert the comments into one of the word processing 
formats we utilize. Please use mailing envelopes designed to physically 
protect the submitted diskettes. We emphasize that submission of 
comments on diskettes is not mandatory nor will it result in any 
advantage or disadvantage to any commenter.
    You should not submit electronically any confidential business 
information (CBI). You must submit an original and two copies of CBI 
under separate cover to: RCRA CBI Document Control Officer, Office of 
Solid Waste (5305W), U.S. EPA, 1200 Pennsylvania Avenue, NW, 
Washington, D.C. 20460. Any CBI data should be specifically and clearly 
marked. In addition, please submit a non-CBI version of your comments 
for inclusion in the public record.
    Supporting documents in the docket for this proposal are also 
available in electronic format on the Internet: http://www.epa.gov/epaoswer/hazwaste/id/inorchem/pr2000.htm>.
    We will keep the official record for this action in paper form. 
Accordingly, we will transfer all comments received electronically into 
paper form and place them in the official record, which also will 
include all comments submitted directly in writing. The official record 
is the paper record maintained at the RCRA Information Center, also 
referred to as the Docket.
    Our responses to comments, whether the comments are written or 
electronic, will be in a notice in the Federal Register or in a 
response to comments document placed in the official record for this 
rulemaking. We will not immediately reply to commenters electronically 
other than to seek clarification of electronic comments that may be 
corrupted in transmission or during conversion to paper form, as 
discussed above.
    You may view public comments and supporting materials in the RCRA 
Information Center (RIC), located at Crystal Gateway I, First Floor, 
1235 Jefferson Davis Highway, Arlington, VA. The RIC is open from 9 
a.m. to 4 p.m., Monday through Friday, excluding federal holidays. To 
review docket materials, we recommend that you make an appointment by 
calling 703-603-9230. You may copy a maximum of 100 pages from any 
regulatory docket at no charge. Additional copies cost $0.15/page.

Customer Service

How Can I Influence EPA's Thinking on This Proposed Rule?

    In developing this proposal, we tried to address the concerns of 
all our stakeholders. Your comments will help us improve this rule. We 
invite you to provide your comments on all data, assumptions and 
methodologies used to support our proposal, your views on options we 
have proposed, your ideas on new approaches we have not considered, any 
new data you may have, your views on how this rule may affect you, and 
other relevant information. Your comments must be submitted by the 
deadline in this proposal. Your

[[Page 55685]]

comments will be most effective if you follow the suggestions below:
     Explain your views as clearly as possible and provide a 
summary of the reasoning you used to arrive at your conclusions. 
Provide examples to illustrate your views wherever possible.
     Provide solid technical data to support your views.
     If you estimate potential costs, explain how you arrived 
at your estimate.
     Tell us which parts of this proposal you support, as well 
as which parts you disagree with.
     Offer specific alternatives.
     Reference your comments to specific sections of the 
proposal by using section titles or page numbers of the preamble or the 
regulatory citations.
     Clearly label any CBI submitted as part of your comments.
     Include your name, date, and docket number with your 
comments.

Contents of This Proposed Rule

I. Overview
    A. Who Potentially Will be Affected by this Proposed Rule?
    B. Why Does this Rule Read Differently from Other Listing Rules?
    C. What are the Statutory Authorities for this Proposed Rule?
II. Background
    A. How Does EPA Define a Hazardous Waste?
    B. How Does EPA Regulate RCRA Hazardous Wastes?
    C. What is the Consent Decree Schedule for and Scope of this 
Proposal?
III. Approach Used in this Proposed Listing
    A. Summary of Today's Action
    B. What Wastes Associated with the 14 Sectors Are Outside the 
Scope of the Consent Decree?
    1. Mineral processing wastes exempt under the ``Bevill'' 
exemptions
    2. Residuals used or reused in different industrial processes
    3. Debris and other nonprocess wastes
    C. What Information Did EPA Collect and Use?
    1. The RCRA Section 3007 Survey
    2. Field work: site visits, sampling and analysis
    3. Other sources
    D. How Did EPA Evaluate Wastes for Listing Determinations?
    1. Listing policy
    2. Characteristic hazardous waste
    3. Evaluations of particular units and pathways of release
    4. Evaluation of Secondary Materials
    E. Description of Risk Assessment Approaches
    1. What risk thresholds were used?
    2. What leaching procedures were used?
    3. How were wastes screened to determine if further assessment 
was needed?
    4. How was the groundwater pathway evaluated?
    5. How was the surface water pathway evaluated?
    6. What are the limitations and uncertainties of the assessment?
    F. Sector-specific Listing Determination Rationales
    1. Antimony oxide
    2. Barium carbonate
    3. Boric acid
    4. Cadmium pigments
    5. Inorganic hydrogen cyanide
    6. Phenyl mercuric acetate
    7. Phosphoric acid from the dry process
    8. Phosphorus pentasulfide
    9. Phosphorus trichloride
    10. Potassium dichromate
    11. Sodium chlorate
    12. Sodium dichromate
    13. Sodium phosphate from wet process phosphoric acid
    14. Titanium dioxide
    G. What is the Status of Landfill Leachate from Previously 
Disposed Wastes?
IV. Proposed Treatment Standards Under RCRA's Land Disposal 
Restrictions
    A. What are EPA's Land Disposal Restrictions (LDRs)?
    B. What are the treatment standards for K176 (baghouse filters 
from production of antimony oxide)
    C. What standards are the treatment standards for K177 (slag 
from the production of antimony oxide that is disposed of or 
speculatively accumulated)?
    D. What are the treatment standards for K178 (nonwastewaters 
from the production of titanium dioxide by the chloride-ilmenite 
process)?
    E. What Other LDR Provisions Are Proposed to Apply?
    1. Debris
    2. Soil
    3. Underground Injection Wells that can be found in the 
administrative record for this rule
    F. Is There Treatment Capacity for the Proposed Wastes?
    1. What Is a Capacity Determination?
    2. What are the Capacity Analysis Results?
V. Compliance Dates
    A. Notification
    B. Interim Status and Permitted Facilities
VI. State Authority
    A. Applicability of Rule in Authorized States
    B. Effect on State Authorizations
VII. Designation of Inorganic Chemical Wastes under the 
Comprehensive Environmental Response, Compensation, and Liability 
Act (CERCLA)
    A. Reporting Requirements
    B. Basis for Proposed RQ Adjustment
VIII. Administrative Assessments
    A. Executive Order 12866
    1. Methodology Section
    2. Results
    B. Regulatory Flexibility Act (RFA), as amended by the Small 
Business Regulatory Enforcement Fairness Act of 1996 (SBREFA), 5 
U.S.C. 601 et seq.
    C. Paperwork Reduction Act
    D. Unfunded Mandates Reform Act
    E. Executive Order 12898: Environmental Justice
    F. Executive Order 13045 : Protection of Children From 
Environmental Health Risks and Safety Risks
    G. Executive Order 13084: Consultation and Coordination With 
Indian Tribal Governments
    H. Executive Order 13132: Federalism
    I. National Technology Transfer and Advancement Act

I. Overview

A. Who Potentially Will Be Affected by This Proposed Rule?

    Beginning January 1, 1999 all documents related to EPA's 
regulatory, compliance and enforcement activities, including rules, 
policies, interpretive guidance, and site-specific determinations with 
broad application, should properly identify the regulated entities, 
including descriptions that correspond to the applicable SIC codes or 
NAICS codes (source: October 9, 1998 USEPA memo from Peter D. 
Robertson, Acting Deputy Administrator of USEPA). Today's action, if 
finalized, could potentially affect those who handle the wastes that we 
are proposing to add to EPA's list of hazardous wastes under the RCRA 
program. This action also may affect entities that may need to respond 
to releases of these wastes as CERCLA hazardous substances. These 
potentially-affected entities are described in the Economics Background 
Document placed in the docket in support of today's proposed rule. A 
summary is shown in the table below.

  Summary of Facilities Potentially Affected by the USEPA's 2000 Inorganic Chemical Manufacturing Waste Listing
                                                    Proposal
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                                                                                                  Number of U.S.
                                                                                                     relevant
                  Item                      SIC code               Industry sector name           inorganic mfg.
                                                                                                    facilities
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1......................................            2816  Inorganic Pigments.....................               3
1......................................            2819  Industrial Inorganic Chemicals, not                   3
                                                          elsewhere classified.
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    The list of potentially affected entities in the above table may 
not be exhaustive. Our aim is to provide a guide for readers regarding 
entities likely to be regulated by this action. This table lists those 
entities that we are aware potentially could be affected by this 
action. However, this action may affect other entities not listed in 
the table. To determine whether your facility is regulated by this 
action, you should examine 40 CFR Parts 260 and 261 carefully in 
concert with the proposed rules amending RCRA that are found at the end 
of this Federal Register document. If you have questions regarding the 
applicability of this action to a particular entity, consult the person 
listed in the preceding section entitled FOR FURTHER INFORMATION 
CONTACT.

B. Why Does This Rule Read Differently From Other Listing Rules?

    Today's proposed listing determination preamble and regulations are 
written in ``readable regulations'' format. The authors tried to use 
active rather than passive voice, plain language, a question-and-answer 
format, the pronouns ``we'' for EPA and ``you'' for the owner/
generator, and other techniques to make the information in today's rule 
easier to read and understand. This new format is part of our efforts 
toward regulatory re-invention, and it makes today's rule read 
differently from other listing rules. We believe that this new format 
will help readers understand the regulations, which should then 
increase compliance, make enforcement easier, and foster better 
relationships between EPA and the regulated community.

C. What Are the Statutory Authorities for This Proposed Rule?

    These regulations are proposed under the authority of Sections 
2002(a), 3001(b), 3001(e)(2), 3004(d)-(m) and 3007(a) of the Solid 
Waste Disposal Act, 42 U.S.C. 6912(a), 6921(b) and (e)(2), 6924(d)-
(m)and 6927(a), as amended several times, most importantly by the 
Hazardous and Solid Waste Amendments of 1984 (HSWA). These statutes 
commonly are referred to as the Resource Conservation and Recovery Act 
(RCRA), and are codified at Volume 42 of the United States Code 
(U.S.C.), Sections 6901 to 6992(k) (42 U.S.C. 6901-6992(k)).
    Section 102(a) of the Comprehensive Environmental Response, 
Compensation, and Liability Act of 1980 (CERCLA), 42 U.S.C. 9602(a) is 
the authority under which the CERCLA aspects of this rule are proposed.

II. Background

A. How Does EPA Define a Hazardous Waste?

    Section 3001 of RCRA and EPA's regulations establish two ways of 
identifying wastes as hazardous under RCRA. A waste may be hazardous 
either if it exhibits certain properties (called ``characteristics'') 
which pose threats to human health and the environment, or if it is 
included on a specific list of wastes EPA has evaluated and found to 
pose unacceptable risks. EPA's regulations in the Code of Federal 
Regulations (CFR) define four hazardous characteristics: ignitability, 
corrosivity, reactivity, or toxicity. (See 40 CFR 261.21 through 
261.24.) As a generator, you must determine whether or not a waste 
exhibits any of these characteristics by testing the material or by 
using your knowledge of the process that produced the waste. (See 40 
CFR 262.11(c).)
    EPA may also conduct a more specific assessment of a waste or 
category of wastes and ``list'' them if they meet criteria set out in 
40 CFR 261.11. As described in 40 CFR 261.11, we may list a waste as 
hazardous if it:

--Exhibits any of the characteristics noted above , i.e., ignitability, 
corrosivity, reactivity, or toxicity (261.11(a)(1));
--Is ``acutely'' hazardous, i.e., if they are fatal to humans or in 
animal studies at low doses, or otherwise capable of causing or 
significantly contributing to an increase in serious illness 
(261.11(a)(2)); or
--Is capable of posing a substantial present or potential hazard to 
human health or the environment when improperly managed (261.11(a)(3)).

    Under the third criterion at 40 CFR 261.11(a)(3), we may decide to 
list a waste as hazardous (1) if it contains hazardous constituents 
identified in Appendix VIII to 40 CFR Part 261, and (2) if, after 
considering the factors noted in this section of the regulations, we 
``conclude that the waste is capable of posing a substantial present or 
potential hazard to human health or the environment when improperly 
treated, stored, transported, or disposed of, or otherwise managed.'' 
We place a chemical on the list of hazardous constituents on Appendix 
VIII only if scientific studies have shown a chemical has toxic effects 
on humans or other life forms. When listing a waste, we also add the 
hazardous constituents that serve as the basis for listing to Appendix 
VII to part 261.
    Residuals from the treatment, storage, or disposal of most listed 
hazardous wastes are also classified as hazardous wastes based on the 
``derived-from'' rule (see 40 CFR 261.3(c)(2)(i)). For example, ash or 
other residuals from the treatment of a listed waste generally carries 
the original hazardous waste code and is subject to the hazardous waste 
regulations. Also, the ``mixture'' rule (see 40 CFR 261.3(a)(2)(iii) 
and (iv)) provides that, with certain limited exceptions, any mixture 
of a listed hazardous waste and a solid waste is itself a RCRA 
hazardous waste.
    Some materials that would otherwise be classified as hazardous 
wastes under the rules described above are excluded from jurisdiction 
under RCRA if they are recycled in certain ways. The current definition 
of solid waste at 40 CFR 261.2 excludes secondary materials from the 
definition of solid waste that are used directly (i.e., without 
reclamation) as ingredients in manufacturing processes to make new 
products, used directly as effective substitutes for commercial 
products, or returned directly to the original process from which they 
are generated as a substitute for raw material feedstock. (See 40 CFR 
261.2(e).) As discussed in the January 4, 1985, rulemaking that 
promulgated this regulatory framework, these are activities which, as a 
general matter, resemble ongoing manufacturing operations more than 
conventional waste management and so are more appropriately classified 
as not involving solid wastes. (See 50 FR 637-640). Our approach to 
these issues is described in more detail below in section III.D.4.

B. How Does EPA Regulate RCRA Hazardous Wastes?

    Wastes exhibiting any hazardous characteristic or listed as 
hazardous are subject to federal requirements under RCRA. These 
regulations affect persons who generate, transport, treat, store or 
dispose of such waste. Facilities that must meet the hazardous waste 
management requirements, including the need to obtain permits to 
operate, commonly are referred to as ``Subtitle C'' facilities. 
Subtitle C is Congress' original statutory designation for that part of 
RCRA that directs EPA to issue those regulations for hazardous wastes 
as may be necessary to protect human health or the environment. EPA 
standards and procedural regulations implementing Subtitle C are found 
generally at 40 CFR Parts 260 through 272.
    All RCRA hazardous wastes are also hazardous substances under the 
Comprehensive Environmental Response, Compensation, and Liability Act 
(CERCLA), as described in section 101(14)(C) of the CERCLA statute. 
This

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applies to wastes listed in 40 CFR 261.31 through 261.33, as well as 
any wastes that exhibit a RCRA characteristic. Table 302.4 at 40 CFR 
302.4 lists CERCLA hazardous substances along with their reportable 
quantities (RQs). Anyone spilling or releasing a substance at or above 
the RQ must report this to the National Response Center, as required in 
CERCLA Section 103. In addition, Section 304 of the Emergency Planning 
and Community Right-to-Know Act (EPCRA) requires facilities to report 
the release of a CERCLA hazardous substance at or above its RQ to State 
and local authorities. Today's rule proposes to establish RQs for some 
of the newly listed wastes.

C. What Is the Consent Decree Schedule for and Scope of This Proposal?

    The 1984 Hazardous and Solid Waste Amendments (HSWA) to RCRA 
require EPA to make listing determinations for several specified 
categories of wastes, including ``inorganic chemical industry wastes'' 
(see RCRA section 3001(e)(2)). In 1989, the Environmental Defense Fund 
(EDF) filed a lawsuit to enforce the statutory deadlines for listing 
decisions in RCRA Section 3001(e)(2). (EDF v. Browner; D.D.C. Civ. No. 
89-0598). To resolve most of the issues in the case, EDF and EPA 
entered into a consent decree, which has been amended several times to 
revise deadlines for EPA action. Paragraph 1.g (as amended) of the 
consent decree addresses the inorganic chemical industry:

    EPA shall promulgate a final listing determination for inorganic 
chemical industry wastes on or before October 31, 2001. This listing 
determination shall be proposed for public comment on or before 
August 30, 2000. The listing determination shall include the 
following wastes: sodium dichromate production wastes, wastes from 
the dry process for manufacturing phosphoric acid, phosphorus 
trichloride production wastes, phosphorus pentasulfide production 
wastes, wastes from the production of sodium phosphate from wet 
process phosphoric acid, sodium chlorate production wastes, antimony 
oxide production wastes, cadmium pigments production wastes, barium 
carbonate production wastes, potassium dichromate production wastes, 
phenyl mercuric acetate production wastes, boric acid production 
wastes, inorganic hydrogen cyanide production wastes, and titanium 
dioxide production wastes (except for chloride process waste 
solids). However, such listing determinations need not include any 
wastes which are excluded from hazardous waste regulation under 
section 3001(b)(3)(A)(ii) of RCRA and for which EPA has determined 
that such regulation is unwarranted pursuant to section 
3001(b)(3)(C) of RCRA.

Today's proposal satisfies EPA's duty under paragraph 1.g to propose 
determinations for inorganic chemical industry wastes.
    As described above, the consent decree provides that EPA does not 
need to make listing determinations for certain wastes that it has 
exempted from hazardous waste regulations under the ``Bevill 
amendments'' to RCRA. See the discussion of ``exempt mineral 
processing'' wastes in section III.B.1 below.

III. Approach Used in This Proposed Listing

A. Summary of Today's Action

    Manufacturers of the inorganic chemical products described above 
identified over 170 categories of residuals generated as part of their 
production processes. We first determined which of these residuals fell 
within the scope of our consent decree obligations. We then evaluated 
the risks posed by each of the remaining categories of residual 
materials. In some cases we used quantitative or qualitative screening 
methods. For 18 wastes we conducted full-scale modeling to predict 
risks.
    As a result of this evaluation, we found that three wastes 
generated in the 14 inorganic chemicals manufacturing operations which 
we evaluated meet the criteria for listing set out in either 40 CFR 
261.11(a)(1) or 261.11(a)(3). We conducted full-scale modeling of two 
of these wastes and propose to list them under 40 CFR 261.11(a)(3). We 
found that one waste warranted listing under 40 CFR 261.11(a)(1) 
because it exhibited hazardous waste characteristics. We did not model 
this waste. Since these are wastes from specific inorganic chemical 
industries, we propose to add them to Section 261.32 with K-waste 
codes. The three wastestreams we propose to list as hazardous, along 
with their corresponding hazard code and proposed EPA Hazardous Waste 
Numbers, are: \1\

    \1\ As required in 40 CFR 262.30, the listing description 
includes the hazard code. Wastes listed under 40 CFR 261.11(a)(1) 
due to the toxicity characteristic are designated ``E,'' and wastes 
listed under 40 CFR 261.11(a)(3) for toxicity are designated ``T''.
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K176  Baghouse filters from the production of antimony oxide. (E)
K177  Slag from the production of antimony oxide that is disposed of or 
speculatively accumulated. (T)
K178  Nonwastewaters from the production of titanium dioxide by the 
chloride-ilmenite process. (This listing does not apply to chloride 
process waste solids from titanium tetrachloride production exempt 
under 40 CFR 261.4(b)(7).) (T)

    We found that all of the remaining wastes that we evaluated did not 
meet the criteria for listing in 40 CFR 261.11, and we are proposing 
not to list them as hazardous wastes. More information on our 
evaluations of particular wastes is set out in the background documents 
and the sector-specific discussions in section III.F of this preamble.
    We have previously listed as hazardous a number of wastes in 40 CFR 
261.32 from other inorganic chemicals industries, including wastes from 
the production of inorganic pigments (codes K002 through K008), and 
wastes from chlorine production (codes K071, K073, and K106). Today's 
proposal does not affect the scope of any existing hazardous waste 
listing, and we are not soliciting comments on those existing listing 
determinations.
    We are also proposing other changes to the RCRA regulations as a 
result of the proposed listings. These changes include adding 
constituents to Appendices VII and VIII for Part 261, and setting new 
land disposal restrictions. We are proposing to add the following 
constituents to Appendix VII that serve as the basis for listing: 
K176--arsenic and lead, K177--antimony, and K178--manganese and 
thallium. We are also proposing to add manganese to the list of 
hazardous constituents in Appendix VIII, based on scientific studies 
that demonstrate manganese has toxic effects on humans and other life 
forms. Section IV of today's proposal describes the proposed changes to 
the land disposal restrictions, which would establish treatment 
standards for specific constituents in the wastes proposed for listing.
    Also as a result of the proposed listings, these wastes would 
become hazardous substances under CERCLA. Therefore, in today's rule we 
are proposing to designate these wastestreams as CERCLA hazardous 
substances, and to adjust the one-pound statutory RQs for two of these 
wastestreams; this is described in section VII of today's proposal.

B. What Wastes Associated With the 14 Sectors Are Outside the Scope of 
the Consent Decree?

    Determining the scope of our consent decree obligations was more 
complicated than usual for two reasons. First, Paragraph 1.g (quoted 
above in II.C) does not tell EPA which wastestreams it must evaluate. 
For most other listing obligations set out in the consent decree, the 
decree specifies particular wastestreams which EPA must evaluate for 
listing. See, for

[[Page 55688]]

example, paragraph 1.k identifying 14 specific petroleum 
wastestreams.\2\ Second, paragraph 1.g contains an exemption for wastes 
found to be exempt from hazardous waste regulation in previous EPA 
actions implementing the so-called ``Bevill exemptions'' for mineral 
processing wastes. Thus, we needed to conduct some analysis to 
determine the scope of our obligations.
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    \2\ The revised consent decree is available in the docket for 
today's proposal.
---------------------------------------------------------------------------

    We began by asking facilities to identify all of the residuals 
generated by their production processes. We then reviewed their lists. 
We found that some residuals were actually exempt ``Bevill'' wastes 
that we need not address. We found that other wastes were really 
associated with the manufacture of other materials. Also, we concluded 
that a few residuals were not ``production'' wastes and therefore were 
not covered by the decree. With the exceptions discussed below in our 
evaluation of the sodium dichromate and titanium dioxide sectors, we 
chose not to evaluate any of the wastes that we considered to be 
outside the scope of the decree. We concluded that evaluation was not 
possible under the time frame set out in the decree. In the following 
sections we provide an overview of the types of wastes that we consider 
outside the scope.
1. Mineral Processing Wastes Exempt Under the ``Bevill'' Exemptions
    Many of the inorganic chemical manufacturing processes we address 
in this rule use ores and minerals as feedstocks. Some wastes derived 
from the processing of ores and minerals are exempt from regulation as 
RCRA hazardous wastes under decisions EPA made under statutory 
requirements known as the ``Bevill'' amendments. RCRA Sections 
3001(b)(3) and 8002(p) required EPA to determine whether wastes from 
the extraction, beneficiation or processing of ores and minerals 
warranted regulation as hazardous wastes under Subtitle C of RCRA. 
Between 1989 and 1991 EPA completed a series of rules and studies 
establishing which mining wastes fit within the ``extraction,'' 
``beneficiation,'' or ``processing'' definitions, and which of the 
wastes within each category were exempt from regulation as hazardous 
wastes. EPA concluded that all wastes produced during extraction and 
beneficiation are entitled to an exemption. EPA found that 20 
categories of wastes from subsequent ``mineral processing'' operations 
met the ``high volume/low toxicity'' criteria and were exempt as well. 
See 54 FR 36592 (Sept. 1, 1989), 55 FR 2322 (Jan. 23, 1990), the July 
31, 1990 Report to Congress on Wastes from Mineral Processing, and 56 
FR 27300 (June 13, 1991).
    EPA codified these ``Bevill'' exemptions at 40 CFR 261.4 (b)(7). 
EPA discussed some of these exemptions further in a 1998 final rule 
promulgating treatment standards for non-exempt mineral processing 
wastes that exhibit the toxicity characteristic. See the Land Disposal 
Restrictions Phase IV Final Rule at 63 FR 28598 (May 26, 1998).
    Paragraph 1.g of the consent decree provides that EPA need not make 
listing determinations for wastes from any of the 14 inorganic chemical 
manufacturing processes which are ``excluded from hazardous waste 
regulation under Section 3001(b)(3)(A)(ii) of RCRA and for which it has 
determined that such regulation is unwarranted pursuant to Section 
3001(b)(3)(C) of RCRA.'' In other words, the consent decree does not 
require us to make listing determinations for wastes which we exempted 
under the statute's ``Bevill'' provisions.
    Paragraph 1.g. of the consent decree requires EPA to make a listing 
determination for ``* * * titanium dioxide production wastes (except 
for chloride process waste solids).'' EPA interprets the exception to 
refer to the chloride process waste solids from the production of 
titanium tetrachloride which are exempt under the Bevill rule, rather 
than all solids from the chloride process. Solids generated after 
titanium tetrachloride forms fall within the scope of the consent 
decree.
    We reviewed the generators' lists of process residuals to determine 
whether they had included any Bevill exempt wastes which we need not 
assess. (In some cases, the generators had claimed that certain wastes 
were exempt under EPA's Bevill decisions.) This process was not always 
simple. We found it was sometimes difficult to determine whether a 
particular facility's waste fit within one of the exempt categories. 
For example, the mineral processing exemption for titanium dioxide 
covers only solid materials from an initial step in the production 
process. It was not always easy to tell whether particular waste solids 
were generated from the portion of the process that would make them 
exempt, or from later production steps. Sector-specific information 
regarding our conclusions appears in section III.F of this preamble for 
those sectors where we found this exemption had some relevance. We 
found that facilities in only three of the consent decree sectors 
generate Bevill exempt wastes: Boric acid, sodium dichromate, and 
titanium dioxide.
    In other sectors, the facilities produce inorganic product 
chemicals from a mineral product. Under the Bevill exemption (54 FR 
36620-21), chemical manufacturing begins if there is any further 
processing of a saleable mineral product. Since these facilities use 
saleable mineral products as feedstock, their processes are chemical 
manufacturing, and may not be classified as mineral processing. 
Therefore, none of the wastestreams generated by these facilities in 
the production of the other inorganic chemicals are Bevill exempt.
    We emphasize that we are not re-opening any Bevill decisions made 
in earlier actions regarding the exemptions. We are not re-defining the 
boundaries between ``extraction'' and ``beneficiation,'' between 
``beneficiation'' and ``mineral processing,'' or between ``mineral 
processing'' and non-exempt chemical manufacturing. Nor are we 
revisiting our decision that all wastes uniquely associated with the 
extraction and beneficiation of ores and minerals are exempt. 
Similarly, we are not re-opening any of our earlier decisions as to 
which categories of mineral processing wastes are exempt. Rather, we 
are determining whether particular wastestreams fall within any of the 
exempt categories. We are not requesting comment on, and do not intend 
to respond to comments relating to the earlier decisions.
    We also found that some inorganic chemical processes generate 
composite wastestreams that contain both a Bevill exempt waste and one 
or more non-exempt wastes. We evaluated the non-exempt portions of such 
wastes to fulfill our consent decree requirements. We apportioned risks 
between the exempt and nonexempt portion of such commingled wastes, and 
made listing determinations for the non-exempt portions. We did not, 
however, assess the exempt portions of such streams. This assessment, 
therefore, does not re-open any earlier decision regarding exemptions 
for the ``Bevill'' component of the commingled streams.
2. Residuals Used or Reused in Different Industrial Processes
    In some cases, facilities within the 14 inorganic chemicals sectors 
set out in the consent decree produce residuals that are used or reused 
in processes that are not among those listed in the decree. Those 
industries in turn produced residuals derived from the materials 
generated in the consent decree industries. We evaluated the

[[Page 55689]]

management of the original industry's material up to the point that the 
second industry inserts it into its production process. However, we 
generally considered the second production process and its associated 
wastes to be beyond the scope of the consent decree. We did not 
evaluate for listing purposes wastes generated from these non-consent 
decree industries. For example, in the titanium dioxide sector, one 
facility uses a residual from the production of titanium dioxide as an 
ingredient to make salt. We considered salt-making to be a separate 
production process outside the scope of the consent decree. We are not 
proposing any listing determinations for wastes generated in the salt 
plant.
    However, in some cases, the reuse of the residual from a consent 
decree process involved an activity which we always regulate as waste 
management. In this situation, we considered the reuse to be waste 
management, and the waste to be within the scope of the consent decree. 
Consequently, we evaluated the residual for listing. For example, we 
found that one of the facilities which produces boric acid generates a 
waste which is used as a fuel. Under our recycling regulations, we 
regulate burning for energy recovery and so, we evaluated this waste. 
See 40 CFR 261.2(c)(2). We found that the waste is already being 
managed in a RCRA Subtitle C unit and decided not to list the waste. 
Others examples of reuse that we evaluated include land application of 
biological treatment solids from hydrogen cyanide production as a 
fertilizer or soil amendment, and land application of gypsum from the 
titanium dioxide sector. In two cases, however, we decided to make 
listing decisions for residuals generated during the production of non-
consent decree products. In the titanium dioxide sector, the residuals 
are commingled with other wastes clearly within the scope of the 
decree. See the discussions of the sodium dichromate sector and the 
titanium dioxide sector in section III.F. In the sodium dichromate 
sector, residuals from the non-consent decree process are piped back to 
the consent decree process, making it difficult to determine whether 
the two processes are really separate.
3. Debris and Other Nonprocess Wastes
    Some generators also identified debris and structural components of 
their production plants as intermittently-generated wastes. We 
concluded that these materials do not fall within the scope of the 
decree. Most of the wastes that fell in this category were refractory 
bricks which become wastes when facilities remove them to refurbish 
their furnaces. We consider this material to be a structural component 
of the plant where production takes place rather than a waste from the 
``production'' of an inorganic chemical. Similarly, we consider a few 
analogous types of plant debris to fall outside the scope of the 
decree. This debris includes miscellaneous construction materials, 
insulation, reactor bed material, and piping. These wastes were 
reported for the following inorganic sectors: Phosphoric acid, barium 
carbonate, sodium dichromate, hydrogen cyanide, antimony oxide, sodium 
phosphate, and titanium dioxide.
    We have never interpreted the decree to require us to consider 
listing tanks, pads, or other structural components housing production 
processes when they become wastes by being removed from use. Other 
paragraphs of the decree support this position. Paragraphs 1.c. (coke 
byproducts) and 1.k. (petroleum refining wastes) cover production 
processes involving reaction vessels lined with refractory or similar 
materials, and in neither case did the decree include wastes related to 
the reaction vessels themselves or related materials. Nor do any other 
provisions in the decree direct us to list any other type of structural 
components. We note that discarded refractory bricks and other debris 
would be regulated as hazardous wastes, if these materials were 
contaminated with a listed waste (including wastes listed as a result 
of today's rulemaking), or if they exhibited a hazardous waste 
characteristic.
    A few facilities also reported environmental media (excavated soils 
or recovered groundwater) contaminated with process residuals as wastes 
from their production processes. We consider such contaminated media to 
be outside the scope of today's listing determinations, because these 
are not wastes generated during production processes, but rather wastes 
generated due to construction or remedial action. We note that none of 
the other consent decree provisions require us to evaluate contaminated 
media. See the specific listing background documents for the different 
sectors for a full listing of the wastes we considered to be out of 
scope of the decree.

C. What Information Did EPA Collect and Use?

    Our investigation of the wastes generated by the inorganic 
chemicals manufacturing industry included two major information 
collection efforts: A survey of the industries and field 
investigations. The survey effort included the development, 
distribution, and assessment of an extensive questionnaire sent under 
the authority of RCRA section 3007 to all known facilities engaged in 
any of the 14 inorganic chemical manufacturing processes. During our 
field investigations we made site visits to familiarize ourselves with 
processes and residuals, and made additional visits to collect samples 
of residuals which we sent to laboratories for analysis. Finally, we 
collected data from other sources to help characterize the settings in 
which some of the wastes are managed. Each of these efforts is 
summarized below.
1. The RCRA Section 3007 Survey
    We developed an extensive questionnaire under the authority of 
Section 3007 of RCRA for distribution to the inorganic chemicals 
manufacturing industry. The purpose of the survey was to gather 
information about solid and hazardous waste generation and management 
practices in the U.S. for the fourteen inorganic chemical industry 
sectors. The questionnaire collected information about the inorganic 
chemical products manufactured, the processes used, the wastes 
generated, the wastes characteristics, and how the wastes were managed. 
The questionnaire is included in the ``General Background Document for 
the Inorganic Chemical Listing Determination.'' which is in the docket 
for today's proposal. This document also provides more details on the 
producers identified in the inorganic sectors.
    We distributed the survey in March of 1999 to all 124 facilities 
that we had identified as potential manufacturers of chemicals in the 
14 targeted sectors. We developed the list of facilities from a review 
of the available literature, which included directories of chemical 
producers, reference works of chemical technology, chemical profile 
information, and previous work by EPA on these industries. From the 
surveys distributed, 57 facilities indicated that they manufacture 
chemicals from at least one of the 14 sectors. The other facilities 
notified us that they had either stopped operations or did not 
manufacture inorganic chemical products. From the survey, we confirmed 
that one product was no longer manufactured in this country (phenyl 
mercuric acetate).
    We also conducted an exhaustive engineering review of the submitted 
surveys for accuracy and completeness. We conducted quality assurance 
reviews of the data to identify any inappropriate entries and missing 
data. The engineering review of each facility's

[[Page 55690]]

response resulted in follow-up letters and/or telephone calls to the 
facilities seeking clarifications, corrections, and additional data 
where needed.
    Where we conducted sampling and analysis of the waste, we used this 
analytical data in our analysis (see the following section). Facilities 
also submitted data in their survey on the composition of some of their 
wastes. In the absence of our own analytical data, we used data 
provided by facilities in our evaluation. These cases are noted in the 
sector-specific discussions in section III.F. In some cases, these data 
consisted of results from testing to determine whether the wastes 
exhibited characteristics. We thought such data were reliable because 
of the consequences the facilities would face if their characteristic 
data were not accurate. In addition, survey respondents were required 
to certify the accuracy of their submittal.
2. Field Work: Site Visits, Sampling and Analysis
    As part of our field work, we visited production facilities 
(engineering site visits), we took preliminary samples (familiarization 
sampling), and we obtained samples to fully characterize the waste for 
constituents of concern (record sampling). We initiated the sampling 
phase of this listing determination with the development of a Quality 
Assurance Project Plan (QAPP) for sampling and analysis. The QAPP 
describes the quality assurance and quality control requirements for 
the data collection. We also developed sampling and analysis plans 
(SAPs) for sampling at individual facilities. The QAPP and the SAPs are 
available in the public docket for this proposal.
    The primary purpose of the engineering site visits was to gain 
first hand knowledge of the manufacturing processes, the waste 
generation and management, and to identify potential locations for 
waste sampling. We conducted site visits at 25 facilities in 12 of the 
sectors. We selected the facilities to visit based on logistics and to 
visit sites that represent the variety of process and wastes generated 
within industry sectors. Site visit reports are available in the docket 
for today's rule. During some of the engineering site visits, we 
collected 22 familiarization samples to help us identify potential 
sampling or analytical problems for the wastes of interest. For 
example, we used the familiarization samples to assess the 
effectiveness of the analytical methods that we planned to use during 
record sampling for a number of the targeted waste matrices.
    During record sampling, we collected 69 waste samples from 13 
different facilities. Additional samples were collected for QA/QC 
purposes. Largely due to the time constraints imposed by our consent 
decree schedule, we focused the sampling effort on the wastes that we 
most expected to present significant potential risks. Based on 
information obtained from the RCRA Section 3007 Surveys, we established 
sampling priorities by considering the reported management practices 
(e.g., wastes going to Subtitle D landfills and impoundments were of 
concern), and the likely presence of contaminants of concern.
    We also found that we were able to make listing decisions on a 
variety of reported wastes without conducting sampling. In some cases, 
we were able to use information about the processes and the raw 
materials to conclude that a waste was not likely to present a 
significant risk. Also, we did not typically sample wastes that were 
reported to be characteristically hazardous waste and were already 
regulated as hazardous under RCRA. We felt that, for these wastes, we 
could make listing decisions without further information on waste 
constituents. In addition, we did not attempt to sample wastes that we 
found to be outside the scope of the consent decree, as described in 
Section III.B. Thus, for example, we did not sample a number of wastes 
that appeared to be exempt under the Bevill regulations.
    We believe that the 69 record samples from 13 sites provide an 
adequate characterization of the wastes that we sampled. The 13 sites 
represent approximately 30% of the 42 identified production facilities 
within the specific sectors we chose for sampling. The wastes sampled 
also represent the major waste types of concern, e.g., specific process 
wastes/sludges, wastewater treatment sludges, wastewaters, and spent 
filter material. Section III.F of this proposal provides information on 
the specific wastes sampled in each sector. The docket for today's 
proposal also contains background documents for the specific sectors, 
which give details on which wastes we sampled and our evaluation of the 
need for sampling or modeling certain wastes.
    For most sectors, we focused our analyses on metal constituents, 
because these are the constituents expected from the inorganic 
processes under evaluation. We analyzed for other constituents in those 
cases where we expected they might be present in the waste, or if other 
constituents showed up in the familiarization sampling. Thus, we 
analyzed wastes from the inorganic hydrogen cyanide industry for 
cyanide and volatile organics because of their potential to be present 
from the process. Similarly, in the titanium dioxide sector, we 
analyzed waste samples for semivolatile and chlorinated organics due to 
the use of coke and chlorine as raw materials in the production process 
for the titanium chloride intermediate. The overall list of target 
analytes are in the QAPP, which is in the docket for today's rule. The 
docket also contains the background documents for each sector and the 
corresponding waste characterization data reports, which show the 
chemical analyses performed and the analytes found in the waste 
samples.
    In our analyses of wastes samples, we performed analyses to measure 
constituent concentrations in the wastes themselves (``total'' 
analysis), as well as analyses for constituents that leach out of the 
wastes. We generally used the methods specified in OSW's methods manual 
(``Test Methods for Evaluating Solid Waste, Physical/Chemical 
Methods,'' SW-846), as described in the QAPP, the SAPs, and the 
background documents for the specific sectors. We used two extraction 
methods to measure leaching, the Toxicity Characteristic Leaching 
Procedure (TCLP, SW-846 method 1311), and the Synthetic Precipitation 
Leaching Procedure (SPLP, SW-846 method 1312).
    In general, we were able to measure the concentrations of 
constituents in waste samples at very low detection levels. However, 
for some constituents in some matrices the SPLP and/or TCLP analyses 
provided detection limits that were somewhat above health-based levels 
of concern. In such cases, we examined all of the analytical data to 
determine if the undetected constituent might possibly present a 
potential risk. Where we did not detect the constituent in the total 
analysis (i.e., the analysis of a sample prior to any leaching), we 
assumed that the constituent was not present in the leachate. However, 
if the totals analysis showed the presence of a constituent that we did 
not detect in the leachate, then we assessed the risk that would be 
posed if the constituent were present at a concentration equal to one-
half the detection limit. Section III.F shows the cases where we used 
this assumption in our evaluation of wastes for the different inorganic 
sectors, and further details are available in the background documents 
for each sector.
3. Other Sources
    We also collected data from a variety of other sources to help 
characterize the settings in which these wastes are managed. For 
example, we contacted

[[Page 55691]]

several state and local authorities to collect information regarding 
the location of drinking water wells. We also obtained information and, 
in some cases analytical data, from state authorities and other sources 
to help in our evaluations. We note these sources in the sector-
specific discussions in Section III.F when we relied on such data.

D. How Did EPA Evaluate Wastes for Listing Determinations?

1. Listing Policy
    As discussed in section II.A. of this preamble, we consider the 
listing criteria set out in 40 CFR 261.11, in light of all the 
information we have relevant to the criteria, in making listing 
determinations. For decisions made under 40 CFR 261.11(a)(3), today's 
proposed listing determinations follow the elements of the EPA's 
hazardous waste listing policy presented the proposed listing for 
wastes generated by the dyes and pigments industry (see FR 66072, 
December 22, 1994). We have modified and adapted this policy in 
subsequent listings. See for example the recent Petroleum Refining 
proposal (60 FR 57747; November 20, 1995) and the Solvents waste 
proposal (61 FR 42318; August 14, 1996).
    This policy uses a ``weight-of-evidence'' approach in which 
calculated risk information is a key factor to consider in making a 
listing determination under 40 CFR 261.11(a)(3). The criteria provided 
in 40 CFR 261.11(a)(3) include eleven factors for determining 
``substantial present or potential hazard to human health and the 
environment.'' We incorporate nine of these factors, as described 
generally below, into our risk evaluation for the wastestreams of 
concern:

--Toxicity (261.11(a)(3)(i)) is considered in developing the health 
benchmarks used in the risk evaluation.
--Constituent concentrations and waste quantities (261.11(a)(3)(ii) and 
261.11(a)(3)(viii)) are used to define the initial conditions for the 
risk evaluation.
--Potential to migrate, persistence, degradation, and bioaccumulation 
of the hazardous constituents and any degradation products 
(261.11(a)(3)(iii), 261.11(a)(3)(iv), 261.11(a)(3)(v), and 
261.11(a)(3)(vi)) are all considered in our evaluation of constituent 
mobility (e.g., leaching from waste) and fate and transport models we 
used to project potential concentrations of the contaminants to which 
individuals might be exposed.

    We considered two additional factors, plausible mismanagement and 
other regulatory actions (261.11(a)(3)(vii) and 261.11(a)(3)(x)) in 
selecting the waste management scenarios we evaluated in our risk 
assessments. For example, we used information that the waste generators 
submitted in their Section 3007 questionnaires to decide what types of 
waste management units are used. Using information about other federal 
environmental regulatory programs, we concluded that some units or some 
pathways did not pose risks requiring evaluation.
    We separately considered the remaining factor, whether the 
available information indicated any impact on human health or the 
environment from improper management of the wastes of concern 
(261.11(a)(3)(ix)). Thus, we examined a variety of databases for 
information on damage incidents for the inorganic chemical production 
processes under investigation. For example, we examined databases for 
information on potential and actual Superfund sites (CERCLIS), releases 
reported under the Toxic Release Inventory System (TRIS), civil cases 
filed on behalf of EPA, and spills and releases reported to the 
National Response Center (NRC). A full description of our search is in 
the docket for this rule.
    Most of the cases found for these industries typically resulted 
from spills or releases of products, and did not provide any useful 
information of possible risks presented by the wastes we evaluated for 
listing. In a few cases we found sites on the Superfund National 
Priority List (NPL) that included inorganic manufacturing processes. 
However these sites usually encompassed a variety of chemical 
manufacturing and mining industries, and it is difficult to attribute 
the damage reported to the specific inorganic manufacturing wastes 
under evaluation. Furthermore, contamination at these sites appears 
linked to historical management practices at closed or inactive 
manufacturing plants, and these were not useful in assessing current or 
potential hazards for the wastes at issue. In addition, Federal and 
State regulatory controls are now in place that would prevent 
mismanagement. For example, many of the wastes examined in today's 
proposal are regulated as characteristic waste, and releases or 
disposal to the land are addressed under the existing RCRA regulations. 
We did not find any evidence of actual damage cases.
    We describe our decisions under 40 CFR 261.11(a)(3) in more detail 
in the sector-specific discussion in section III.F below, and in the 
background documents. Generally, we conducted full-scale risk modeling 
for 18 wastes in 5 sectors. We found that we could adequately address 
the risks of the remaining wastes with a variety of less time-consuming 
approaches. Some were qualitative; others were quantitative, but not as 
complex as full modeling.
    We evaluated one waste using the single criterion set out in 40 CFR 
261.11(a)(1) rather than the eleven factors referenced in 40 CFR 
261.11(a)(3). This is the first time under this consent decree that we 
have proposed to make a listing decision based on this criterion. It 
relies on the existing characteristics to identify wastes posing 
significant risks and does not require the use of modeling. See the 
discussion of wastes from the production of antimony oxide in section 
III.F.1 of the preamble.
    Our proposed listing determinations are based upon estimates of 
individual risk. We relied on individual risk estimates (HQs > 1), and 
not population risk estimates, because we are concerned about risks to 
individuals who are exposed to potential releases of hazardous 
constituents. We believe that using individual risk as a basis for our 
listing determinations (rather than population risk estimates) also is 
appropriate to protect against potential risks, as well as present 
risks that may arise due to the generation and management of particular 
wastestreams. EPA acknowledges that in cases where small populations 
are exposed to particular wastes and waste management practices, 
population risks may be very small. We did not attempt to calculate 
population risks for the proposed listings. In general, we expect 
population risks arising from contaminated groundwater due to waste 
management to be small, because often only a limited number of domestic 
wells will be near these facilities, and groundwater contamination 
often moves very slowly. Nevertheless, the increased risk for an 
exposed individual may be significant. In proposing the listing 
determinations for K176, K177, and K178, EPA is protecting against the 
potential risk for exposed individuals, regardless of how many 
individuals are exposed.
    We set out below general observations about some of our approaches 
to risk assessment.
2. Characteristic Hazardous Waste
    We describe in Section a. below our analysis for wastes which are 
``100% characteristic''--wastes which all generators report as 
characteristic and which all generators appear to manage in compliance 
with applicable hazardous waste regulations. We

[[Page 55692]]

describe our approach to wastes which are occasionally characteristic--
but managed in compliance--in Section b. below. Finally, we discuss in 
Section c. one waste which appears to exhibit a characteristic 
frequently, but does not appear to be managed in compliance with 
hazardous waste regulations.
    a. Wastes consistently exhibiting characteristics. For wastes which 
these industries identified as characteristic and managed in compliance 
with hazardous waste regulations, we are proposing to find that there 
is no ``plausible mismanagement'' scenario to evaluate for listing. 
(See 40 CFR 261.11(a)(3)(vii).) The Subtitle C rules applying to 
characteristic wastes adequately protect human health and the 
environment, especially where waste generators are complying with them. 
40 CFR 261.11(a)(3)(x) authorizes us to consider actions taken by other 
regulatory programs. We believe we can reasonably interpret this to 
include the rules for characteristic wastes under Subtitle C .
    We acknowledge that the regulation of characteristic wastes differs 
in some ways from the regulation of listed wastes. For example, for 
characteristic wastes, residues from treatment required by the land 
disposal restrictions need not always be placed in hazardous waste 
disposal units. However, we do not regard the differences as 
``mismanagement.'' Rather, we believe that both approaches protect 
human health and the environment. Consequently, for the purposes of 
this rule we decided that we would not propose to list a ``100% 
characteristic'' waste unless we found evidence of extraordinary risks 
under one or more of the other factors in 40 CFR 261.11(a)(3).
    For a few of the 100% characteristic wastes in this rule, we found 
factors warranting further consideration. For example, we found that 
the sole generator of cadmium pigment wastes codes them as hazardous, 
arranges for treatment to comply with the land disposal restrictions, 
and then disposes of treated residues in a Subtitle D landfill. At the 
same time, we found that the waste contains very high levels of 
cadmium. We decided to investigate further to ensure that the treatment 
residues did not present significant risks. We examined data relating 
to the treatment process and leachate monitoring data from the landfill 
receiving the residues. Based on these data, we concluded that the 
residues did not pose risks warranting listing.
    b. Wastes which sometimes exhibit characteristics. Information 
submitted in responses to the Section 3007 questionnaires also showed 
that there are a number of wastes that exhibit characteristics at some 
facilities, but not others. Consistent with previous listing decisions 
(see for example, the most recent petroleum refining listing at 63 FR 
42137), we focused on the volumes of waste that did not exhibit 
characteristics in our listing evaluation. For wastestreams identified 
as exhibiting characteristics and apparently managed in compliance with 
applicable regulations, we relied on the ``no plausible mismanagement'' 
and ``other regulations'' analysis described above. A hypothetical 
example follows. If one facility generated 40 tons per year of a 
properly-managed characteristic waste, and a second facility generated 
60 tons per year of a non-characteristic waste, we would not evaluate 
the total of 100 tons of waste under a single approach. Rather, we 
would evaluate the characteristic waste under the approach described 
above. For the waste that did not exhibit a characteristic, we would 
conduct the type of risk assessment described below in section III.E.
    c. Characteristic wastes not managed in compliance with Subtitle C. 
In one case, we found a characteristic waste where we believe that 
existing Subtitle C rules do not adequately prevent mismanagement. Four 
facilities generate a baghouse filter waste from the production of 
antimony oxide. Data from our sampling and analysis at 2 facilities 
showed exceedences of the toxicity characteristic. Two facilities 
recycle these wastes in a manner that may comply with applicable 
regulations. Two other facilities, however, did not identify their 
waste as characteristic wastes, and appear to manage them in ways which 
do not comply with Subtitle C rules. Because of this apparent 
noncompliance, we concluded that it would be appropriate to disregard 
the characteristic rules in an analysis of the factors in 40 CFR 
261.(a)(3). However, we also concluded that it was not necessary to 
conduct such an analysis. Since this waste fails the toxicity 
characteristic, it clearly contains levels of constituents which could 
pose threats to human health via groundwater when placed in a municipal 
landfill, if leachate were to migrate to a drinking water well at 
sufficient concentrations. Since the generators are not managing the 
wastes in compliance with applicable Subtitle C regulations, we assume 
that this type of mismanagement could occur at other sites. 
Accordingly, we exercised our authority to propose to list this waste 
under 40 CFR 261.11(a)(1). As noted above, this provision authorizes 
(but does not require) EPA to list wastes that exhibit characteristics 
without the analysis required under 40 CFR 261.11(a)(3). We believe 
that noncompliance is an appropriate reason to use this authority to 
list a characteristic waste.
    d. Non-characteristic wastes disposed of in hazardous waste units. 
We identified nine wastes which do not appear to exhibit any 
characteristic, but which are disposed of in Subtitle C management 
units. Four of these wastes are sent to combustion unit regulated under 
Subtitle C of RCRA. The remaining 5 wastes are sent to Subtitle C 
landfills. We found that all of these wastes receive some treatment 
before land disposal. In one case available data indicates that the 
waste meets applicable LDR treatment standards as generated.
    In general, these wastes have very limited potential for 
mismanagement under 40 CFR 261.11(a)(3)(vii). This is particularly true 
for wastes which generators place in on-site, Subtitle C units with 
ample capacity. Also, in some cases, some of the wastes are generated 
in very small quantities (less than 1 metric ton per year). These 
wastes are distinguishable from a non-characteristic organobromine 
waste sent to a hazardous waste unit that we decided to list in 1998. 
That waste had extremely high concentrations of a constituent posing 
significant risks, and received no treatment (see May 4, 1998; 63 FR 
24596).\3\ We request comment on the individual rationales set out in 
the sector-specific discussions and the background documents.
---------------------------------------------------------------------------

    \3\ On April 9, 1999, the D.C. Circuit in Great Lakes Chemical 
Corporation v. EPA ordered that the organobromine listing 
determinations be vacated. Accordingly, EPA removed the listings 
from CFR (see 65 FR 14472: March 17, 2000).
---------------------------------------------------------------------------

3. Evaluations of Particular Units and Pathways of Release
    We are proposing to find that some pathways of release from some 
units present low risks because they are adequately controlled under 
other Federal environmental regulations that minimize the likelihood of 
releases. We are also proposing to find that other risk pathways 
present low risks due to physical or chemical attributes of the wastes. 
In some cases, we evaluated all release pathways at a single unit under 
a combination of these approaches.
    a. Wastewater management. Facilities in these industries generally 
treat wastewaters in on-site wastewater treatment plants and discharge 
to surface waters, or pretreat the waste and discharge to an off-site 
wastewater

[[Page 55693]]

treatment facility, e.g., a Publicly Owned Treatment Works (POTW). 
Under the Clean Water Act (CWA), discharges to surface waters are 
controlled under the National Pollutant Discharge Elimination System 
(NPDES) and require an NPDES permit, while discharges to a POTW are 
subject to State and national pretreatment standards.\4\ Point source 
discharges for the various sectors in the inorganics listing are 
regulated under the CWA by the effluent guidelines and pretreatment 
standards in 40 CFR Parts 415 (Inorganic chemical manufacturing) and 
422 (Phosphate manufacturing). Therefore, we did not evaluate NPDES 
effluent or discharges to POTWs in today's proposal. This approach is 
consistent with other listing rules. See, for example, 60 FR 57759 
(November 20, 1995, petroleum refining wastes proposal). In a few 
cases, facilities reported disposal of wastewaters by deep well 
injection in a permitted Class I UIC hazardous waste injection well. In 
these cases, the wells were units regulated by the Underground 
Injection Control (UIC) program under the Safe Drinking Water Act (40 
CFR Part 144). These wells also had no migration exemptions under 
Section 148.20 to allow disposal of untreated hazardous waste. 
Therefore, we did not evaluate this scenario further.
---------------------------------------------------------------------------

    \4\ In fact, 40 CFR 261.4 excludes ``any mixture of domestic 
sewage and other wastes that passes through a sewer system to a POTW 
for treatment'' (40 CFR 261.4(a)(1)(ii), and industrial wastewater 
discharges that are point source discharges subject to regulation 
under Section 402 of the CWA (40 CFR 261.4(a)(2)).
---------------------------------------------------------------------------

    For surface impoundments, we concluded that releases to air were 
not likely to present concerns. For most sectors, the constituents of 
concern are nonvolatile metals, and this makes volatilization a highly 
unlikely pathway for constituents from normal wastewater treatment 
practices. We recognize that releases of volatile organic chemicals 
from impoundments may be a potential route of concern for one sector, 
inorganic hydrogen cyanide production. EPA is developing maximum 
achievable control technology (MACT) standards for cyanide 
manufacturing under the Clean Air Act (CAA), which may address these 
emissions.\5\ EPA is evaluating possible air releases from wastewaters 
in impoundments as part of the MACT rulemaking. Therefore, we did not 
do any further evaluation of these emissions as part of today's listing 
determination. We assessed the potential for groundwater releases from 
the impoundments.
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    \5\ Clean Air Act--Title III: Upcoming MACT Standards--Cyanide 
Chemical Manufacturing; Unified Air Toxics Website: http://www.epa.gov/ttn/uatw/mactupd.html: The hydrogen cynaide industry 
would also be subject to regulations under 40 CFR Part 60, Subpart 
YYY under the CAA for volatile organic compound (VOC) emissions from 
wastewater treatment at facilities in the synthetic organic chemical 
manufacturing industry (SOCMI), which was proposed September 19, 
1994 (59 FR 46780).
---------------------------------------------------------------------------

    For sectors and wastes where facilities did not use surface 
impoundments for wastewater management, we determined that ``plausible 
mismanagement'' would be continued management in existing tank-based 
treatment systems. We do not view abandonment of existing treatment 
systems for surface impoundments as ``plausible,'' because the 
manufacturers have already made a considerable investment in wastewater 
treatment systems using tanks and will continue to use them. Further, 
we assumed that wastewater treatment tanks retain sufficient structural 
integrity to prevent wastewater releases to the subsurface (and 
therefore to groundwater), and that overflow and spill controls prevent 
significant wastewater releases. Thus, based on the lack of any 
significant likelihood of release of the constituents to groundwater, 
we did not project significant risks to groundwater from these wastes 
in the tank-based wastewater treatment scenario. We did not model any 
releases to groundwater from tanks. This is consistent with our 
approach in other listing rules (see, for example, the proposed rule 
for chlorinated aliphatics production wastes at 64 FR 46476; August 25, 
1999). We also considered the possibility of air releases from tanks. 
For most wastes, the constituents of concern are nonvolatile metals, 
making volatilization a very unlikely pathway of release from tanks. 
For the hydrogen cyanide sector, where volatile compounds are likely 
and tanks are used in wastewater treatment systems, the tanks will also 
be covered by other CAA regulations as described above. In addition, in 
many cases facilities have installed tank covers, further reducing the 
likelihood of release to the air. As a result, we have not modeled 
releases to air from tanks for any wastes in this listing 
determination.
    b. Waste solids management. We concluded that we did not need to 
model any releases of volatile constituents from solids for the same 
reasons set out above. The management practices of concern for waste 
solids were landfills, including disposal in on-site and off-site 
landfills, and in a few cases, waste piles. We evaluated the potential 
for groundwater releases from all landfills and piles. We also 
considered the possibility of releases of airborne particulates by a 
multistep process where we compared the total concentrations of the 
constituents of concern to a series of soil screening levels (see 
section III.E.3).
4. Evaluation of Secondary Materials
    RCRA gives EPA jurisdiction only over materials that are discarded. 
EPA's current definition of discard is set out in the definition of 
solid waste at 40 CFR 261.2. Under this approach, process residuals (or 
``secondary materials'') destined for recycling are solid wastes within 
our jurisdiction if the recycling closely resembles waste management. 
Conversely, if the materials are recycled as part of an ongoing 
manufacturing process, they are not solid wastes. The existing rules 
specifically exclude secondary materials from jurisdiction that are 
used directly (without reclamation), as ingredients in manufacturing 
processes to make new products, used directly as effective substitutes 
for commercial products, or returned directly to the original process 
from which they are generated as a substitute for raw material 
feedstock. 40 CFR 261.2(e). In addition, the existing rules allow for 
closed loop reclamation where secondary materials can be reclaimed and 
returned to the original production process provided that the entire 
process is closed, the reclamation does not involve controlled flame 
combustion, and the reclaimed material is not used to produce a fuel or 
a material that is used in a manner constituting disposal. (40 CFR 
261.4(a)(8)) As discussed in the January 4, 1985, rulemaking, these are 
activities which, as a general matter, resemble ongoing manufacturing 
operations more than conventional waste management and so are more 
appropriately classified as not involving solid wastes. However, 
materials which would otherwise qualify for exclusion under these 
provisions are not excluded if EPA finds that the recycling is not 
legitimate. EPA considers a variety of economic and chemical factors 
when it determines whether or not a specific recycling practice is 
legitimate. (See Memorandum from Sylvia K. Lowrance, Director Office of 
Solid Waste, concerning F006 Recycling, dated April 26, 1989). These 
determinations are very site-specific and tend to be very time 
consuming. EPA typically makes them in the context of site-specific 
enforcement or permitting actions.
    The existing rules, however, do not exclude materials that are 
either contained in or used to produce fuels or that are directly used, 
or incorporated into a product that is used, in a manner constituting 
disposal. EPA asserts RCRA jurisdiction for these types of use/reuse

[[Page 55694]]

circumstances as they more closely resemble conventional waste 
management rather than ongoing manufacturing. (See 50 FR 637-640, 
January 4, 1985).
    A series of court decisions also address the issue of our 
jurisdiction over recycled materials. In general, they hold that EPA 
lacks authority to regulate materials that are immediately reused in an 
ongoing manufacturing or industrial process. American Mining Congress 
v. EPA (824 F. 2d 1177 (D.C. Cir. 1987) (AMC I)); American Mining 
Congress v. EPA (907 F. 2d 1179, 1186 (D.C. Cir. 1990) (AMC II)); 
American Petroleum Institute v. EPA (216 F. 3d 50 (D.C. Cir. 2000)). 
The most recent decision, Association of Battery Recyclers, Inc. v. EPA 
(208 F. 3d 1047 (D.C. Cir 2000)), remanded a rule regulating the reuse 
of some closely related materials. We are still evaluating the impacts 
of this decision. However, the remand does not affect this rule because 
we are not relying on the exemptions in the remanded rule.\6\
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    \6\ On May 26, 1998, we promulgated a conditional exclusion from 
the definition of solid waste for secondary materials (other than 
listed wastes) generated within the primary mineral processing 
industry from which minerals, acids, cyanide, water, or other values 
are recovered by mineral processing, with certain provisions. 
Because this conditional exclusion only applied to non-listed 
wastes, and we were making listing determinations, we did not use 
this exclusion as a basis to not evaluate wastes for listing 
purposes. On April 21, 2000, the D.C. Circuit Court issued a 
decision vacating a portion of this conditional exclusion. [See 
Association of Battery Recyclers, Inc. v. EPA. 208 F.3d 1047 (D.C. 
Cir. 2000)].
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    For almost all of the residual materials from these manufacturing 
processes which are re-used or recycled in some way, we decided not to 
attempt to determine whether the recycling practice is not subject to 
regulation under the court decisions and regulations described above. 
Such determinations can be very time-consuming, particularly where we 
find recycling practices that appear not to be regulated, and then need 
to determine whether or not such practices are legitimate. 
Consequently, we decided that it would be more efficient to examine 
first the potential risks posed by the reported recycling practices. If 
we found no significant risks, we would decide not to list the 
material. If, on the other hand, we found risks, we evaluate the 
recycling practice prior to making a listing decision.
    To assess the risks of materials recycled on-site by reusing them 
in one of the consent decree manufacturing processes, we first 
evaluated the management of the materials prior to their re-use. We 
looked for closed piping, covers on containers, or similar barriers to 
releases to the environment. Where we found such management practices, 
we determined that there was no significant potential for releases. We 
then evaluated the potential for releases from the consent decree 
process itself. We found that the only points at which releases were 
expected were either those where we were already evaluating solid 
wastes for the purposes of this listing or points where the facility 
released uncontained gases outside of RCRA jurisdiction. Consequently, 
we felt that we were evaluating all of the potential risks (within our 
jurisdiction) associated with the recycling of these materials. In the 
antimony oxide sector, however, we found one residual that was being 
held in containers for several years for potential reuse. Our rules 
identify this practice as ``speculative accumulation'' and classify the 
materials held in such a manner as solid wastes. Accordingly, we 
assessed the risks posed by these accumulated wastes.
    We found that a few materials are inserted into separate 
manufacturing processes co-located on-site with consent decree 
processes. We evaluated the potential for releases prior to reinsertion 
into that separate process. However, as explained above in section 
III.B, we did not evaluate any risks posed by use of residuals in 
processes that are not subject to our consent decree deadline.
    We also considered the risks of materials recycled off-site. We 
considered the potential for release before the materials were 
transferred off-site. We did not assess the off-site uses which 
involved non-consent decree manufacturing processes. In a few cases, 
however, we found that the reuse involved land placement or burning for 
energy recovery. These activities are always regulated as waste 
management under the rules and court decisions described above. In 
those cases, we concluded that the materials were wastes from the 
consent decree process where they were generated, and we evaluated 
risks posed by the use. For example, we evaluated the risks posed by 
use of residual materials from the production of boric acid as fuels 
for cement kilns. In one case involving antimony oxide residuals, we 
found that the residuals were sent off-site to another smelter 
producing antimony oxide. This smelter happens to be located outside of 
the country. We did not evaluate risks from its residuals, as we have 
no legal jurisdiction to regulate them. We have evaluated the 
production of antimony oxide within the U.S. in this rulemaking, so we 
have evaluated the risks that would be posed if this generator changed 
its practice and sent the materials to an antimony oxide smelter 
located within the U.S.
    For purposes of convenience, in the sector specific discussions 
below (and in the various background documents) we describe all of the 
residuals as wastes. We emphasize, however, that we have not determined 
whether any of the residuals that are recycled are solid wastes as 
defined in 40 CFR 260.2. We believe it is more appropriate to leave 
such site-specific determinations to other decision-making processes.

E. Description of Risk Assessment Approaches

    Before turning to the details of the risk assessment approaches 
used, we want to highlight two general issues. First, we note that for 
this proposal we used a variety of screening methodologies to assess a 
large number of wastes. Due to time constraints imposed by the consent 
decree schedule, we chose --where appropriate-- to use these 
methodologies rather than conducting more time-consuming, full-scale, 
risk assessment modeling. In general, however, we believe that these 
screening methodologies conservatively assessed risks, so that wastes 
that we ``screened out'' are unlikely to present significant risks.
    Second, we want to describe our selection of plausible 
mismanagement practices for both screening and full modeling 
assessments. In general, we assessed the types of management units 
which, according to data available to us, facilities have actually used 
or contemplated using. Frequently, we found that facilities had made 
economic investments that would make them likely to continue to use the 
same types of units. For example, where facilities had paid to install 
tanks to store or treat wastes, we assumed that they would continue to 
use tanks rather than place wastes in pits or surface impoundments. 
Furthermore, we found that some waste quantities were so large that it 
would be prohibitively expensive to transport wastes off-site. 
Similarly, where facilities had installed piping to return residual 
materials to their production processes, we assumed that they would 
continue to use these systems to recycle those residuals. We also 
assumed that such facilities had found it more economical to return 
those residuals to their processes, and were thus not likely to send 
them to landfills or other types of disposal units.
    We seek comment on all data, assumptions and methodologies used in 
our risk assessment for this proposal.

[[Page 55695]]

1. What Risk Thresholds Were Used?
    EPA's listing program generally defines risk levels of concern for 
carcinogens as risks within or above a range of 1 x 10-6 to 
1 x 10-4 (from 1 in 1,000,000 to 1 in 10,000) at the upper 
end of the risk distribution (e.g., 90th or 95th percentile risk for a 
particular exposure scenario). The level of concern for non-cancer 
effects is generally indicated by a hazard quotient (HQ) of 1 or 
greater at the upper end of the distribution. Consistent with the 
listing policy described in the dyes and pigments proposal (59 FR 
66075-66078) we used a 1 x 10-5 risk level and/or HQs of one 
to identify which wastes are candidates for listing. To make a listing 
determination, we then used a weight-of-evidence approach that 
considers the risk estimates along with other information related to 
the factors described in 40 CFR 261.11(a)(3). For cancer, a risk 
threshold of one in 1,000,000 represents the probability that an 
individual will develop cancer over a lifetime as a result of exposure 
to a chemical contaminant. When we estimate the lifetime excess cancer 
risk, we use an upper bound estimate of the carcinogenic slope factor 
(CSF) as derived from laboratory studies in animals or from human 
epidemiological studies. In addition, because the CSF typically relies 
on a number of extrapolations (e.g., from animals to humans and from 
high doses to low doses) there is some uncertainty in the value of the 
CSF.
    For non-cancer effects, which include a wide variety of health 
effects, we used EPA's reference dose (RfD) as a risk threshold. A 
reference dose is an estimate of an oral exposure that is likely to be 
without an appreciable risk of adverse effects in the general 
population, including sensitive individuals, over a lifetime. The RfD 
can be derived from a NOAEL, LOAEL, or benchmark dose. Uncertainty 
factors are applied to address limitations of the available 
toxicological data and are necessary to ensure the RfD is protective of 
individuals in the general population. The use of uncertainty factors 
is based on long-standing scientific practice. Uncertainty factors when 
combined commonly range from 10 to 1000 depending on the nature and 
quality of the underlying data. The RfD methodology is expected to have 
an uncertainty spanning perhaps an order of magnitude. To assess risks 
associated with non-cancer effects, we used a hazard quotient (HQ), 
which is defined as the ratio of the estimated dose of a given chemical 
to an individual to the reference dose for that chemical. A hazard 
quotient (HQ) of one (1) indicates that the estimated dose is equal to 
the reference dose (RfD) and, therefore an HQ of 1 is EPA's threshold 
of concern for non-cancer effects. Usually, doses less than the RfD 
(HQ1) are not likely to be associated with adverse health risks and, 
therefore, are less likely to be of regulatory concern. As the 
frequency and/or magnitude of the exposures exceeding the RfD increase 
(HQ>1), the probability of adverse effects in a human population 
increases. However, it should not be categorically concluded that all 
doses below the RfD are ``acceptable'' (or will be risk-free) and that 
all doses in excess of the RfD are ``unacceptable'' (or will result in 
adverse effects).
    The values of the CSF and RfD that we use for assessing risks are 
generally taken from EPA's on-line toxicity data base called IRIS. 
However, in some cases we used EPA's compilation of toxicity benchmarks 
known as HEAST or other sources, such as toxicological issue papers 
prepared by EPA's National Center for Environmental Assessment 
(NCEA).\7\
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    \7\ EPA's Integrated Risk Information System (IRIS) may be found 
at http://www.epa.gov/iris. See also ``Risk Assessment for the 
Listing Determinations for Inorganic Chemical Manufacturing Wastes'' 
(August 2000) for a discussion of the toxicity benchmark values used 
in today's rule.
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2. What Leaching Procedures Were Used?
    As noted in III.C, we used the TCLP and SPLP leaching procedures to 
evaluate the wastes in today's rule. EPA developed the TCLP as a tool 
to predict the leaching of constituents from the waste in a municipal 
solid waste landfill, and the TC regulations use this method to 
determine if a waste is hazardous under 261.24 (see the Toxicity 
Characteristic rule, 55 FR 46369; November 2, 1990). We have also used 
the TCLP in the listing program to estimate leaching concentrations for 
use in groundwater modeling (for example, see the recent petroleum 
listing, 63 FR 42110, August 6, 1998). We believe the TCLP is the most 
appropriate leaching procedure to use for wastes in municipal 
landfills, because the leaching solution is similar to the type of 
leachate generated from the decomposition of municipal waste. The TCLP 
leaching solution is a solution containing acetic acid that is adjusted 
to a pH of 4.93 or 2.88, depending on the acidity of the waste sample.
    EPA developed the SPLP as a method to predict leaching from wastes 
or soils under exposure to the slightly acidic, dilute solution 
generated by normal rainfall. The SPLP test uses a leach solution which 
mimics acid rain, while the TCLP uses a leach solution which mimics 
acids formed in municipal landfills. In past actions, EPA has 
recognized that the TCLP's use of organic acids may not be appropriate 
for disposal scenarios that do not involve municipal landfills. For 
example, in the proposed rule for management and disposal of lead-based 
paint debris, EPA used the SPLP to assess leaching from landfills that 
do not accept municipal wastes (see 63 FR 70189; December 18, 1998). 
Similarly, EPA utilized the SPLP in screening low hazard wastes as part 
of its 1989 Bevill determination (see 54 FR 36592; September 1, 1989).
    In the context of EPA's more recent mineral processing sector 
actions, we considered the relative merits of both the TCLP and the 
SPLP for various wastes in the mineral processing industries; EPA 
decided to continue to rely on the TCLP for defining characteristically 
hazardous Bevill wastes, in part because we found that disposal in 
municipal landfills did occur for some sectors. See the Land Disposal 
Restrictions Phase IV Final Rule at 63 FR 28598 (May 26, 1998). For 
today's rule, however, we have specific data showing that some wastes 
do not go to municipal landfills and are unlikely to be disposed of in 
municipal landfills. We used the SPLP sampling results for wastes that 
were not likely to go to municipal landfills, and we used the TCLP 
results for wastes going to municipal landfills.
3. How Were Wastes Screened To Determine If Further Assessment Was 
Needed?
    We used a number of approaches to eliminate from further 
consideration those wastes that could not plausibly pose unacceptable 
risks. This served to identify those wastes and chemical constituents 
that required further assessment. Different screening approaches were 
used depending on the type of waste management practices employed in 
the industry and, in some instances, the waste volume and the location 
of the waste management units.
    For wastes that are managed in landfills, groundwater contamination 
is the primary source of human exposures, particularly for certain 
metals and other inorganic compounds that are nonvolatile, such as 
those present in the wastes that are the subject of today's rule. We 
compared leachate concentrations derived from the TCLP or SPLP test 
measurements to levels in drinking water that are protective of human 
health. These levels, referred to as health-based levels (HBLs), are 
designed to be protective of both

[[Page 55696]]

children and adults. Health-based levels (HBLs) are levels in 
environmental media that would not exceed EPA's risk thresholds given 
conservative assumptions regarding exposure (e.g., a level in drinking 
water that would not exceed a risk threshold for an individual whose 
drinking water intake was at the high end of the distribution for the 
general population).\8\ Although an HBLs represents a concentration 
level at the point of exposure, we conservatively assumed direct 
contact with the wastes (i.e., no dilution) for the purpose of 
screening out wastes and chemical constituents that could not pose 
unacceptable risks and, therefore, do not merit further analysis. As 
explained previously, we used SPLP measurements for wastes that are 
managed in landfills containing only industrial wastes and TCLP 
measurements for wastes that are managed in landfills which also 
contain municipal wastes. For wastewaters that are managed in surface 
impoundments, we used the concentration in the filtered liquid (i.e., 
the SPLP filtrate) because the filtrate is more representative of the 
fraction of the waste that could infiltrate into the subsurface 
environment. Regardless of the type of measurement, if the result of 
the chemical analysis for a particular compound was below the limit of 
detection but the compound was detected in the waste, then we used \1/
2\ the value reported by the laboratory as the limit of detection for 
that compound. Any chemical contaminant in a waste that did not screen 
out against HBLs (i.e., the waste concentration was a factor of 2 or 
less times the HBLs \9\) we identified as a constituent of concern 
(CoC) requiring further assessment. However, very low volume wastes 
were subject to further screening, as described below.
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    \8\ Details on how HBLs are derived may be found in the risk 
assessment background document for today's proposal, ``Risk 
Assessment for the Listing Determinations for Inorganic Chemical 
Manufacturing Wastes'' (August 2000).
    \9\ We used professional judgment to screen out constituents 
with concentrations within a factor of two of the HBLs. 
Historically, our models have suggested that the dilution and 
attenuation of constituents in the subsurface will generally result 
in dilution and attenuation factors (DAFs) of 2 or greater. (See, 
for example, the DAFs estimated for the petroleum refining listing 
determination, 63 FR 42110, and the docket for today's rulemaking 
for DAFs calculated to support today's proposal.) If our 
consideration of site-specific factors had indicated that a very low 
DAF were likely for actual exposure (e.g. known drinking water wells 
placed very close to the management until boundary), we would have 
modeled that waste rather than screening it out using professional 
judgment.
---------------------------------------------------------------------------

    For very low volume wastes that did not screen out against HBLs, we 
performed an additional conservative screen to determine if the waste 
could plausibly pose a risk to human health when disposed of in a 
landfill. Typically wastes generated in volumes of less than 1 or 2 
metric tons per year were considered as candidates for this de minimis 
analysis. This analysis assumed that the entire mass of the chemical 
contaminant in a volume of waste that is generated in a year's time 
would leach out of the waste and infiltrate into groundwater in the 
same year. The only dilution that was assumed to occur was with the 
volume of water that infiltrated into the landfill. To minimize the 
amount of dilution we chose a conservative infiltration rate based on 
the infiltration that could occur for a relatively low permeability 
soil underlying a relatively small landfill (corresponding to the 10th 
percentile of the distribution of municipal landfill areas nationwide). 
However, in some cases the resulting infiltration was less than the 
amount of water that would be withdrawn from a well by a household for 
domestic usage. In these instances, we diluted the infiltrate into the 
minimum volume of water needed to support a household well, which we 
estimated from data on U.S. per capita water consumption assuming a 
family of four. The concentration derived using this procedure was then 
compared to the HBLs. Any chemical contaminant that did not screen out 
as a result of this analysis we identified as a constituent of concern 
(CoC) requiring further assessment. While we do expect the de minimis 
screen to be conservative overall, the degree to which it is 
conservative depends on many waste and site-specific factors. (For 
example, our sampling and analysis data indicate that in some cases 
essentially all of the chemical constituent leached out of the sample 
over the duration of the leach test.)
    For wastes managed in waste piles and landfills, we performed a 
multi-level screening analysis to determine if further assessment of 
the air pathway was needed. Wind blown dust from wastes managed in 
piles is a potential source of human exposures. This pathway is also 
possible for landfills, but likely to result in much lower releases due 
to the common usage of daily and longer-term cover at landfills. In the 
first level screen we compared the waste contaminant total 
concentrations to background levels in soils. Background soil levels 
were taken from published compilations of levels in native soils 
nationwide and were generally characterized using a geometric mean or 
(in a few instances) an arithmetic mean concentration of the available 
data.\10\ If the waste concentrations exceeded background levels in 
soils, we performed a second level screen by comparing the waste 
concentrations with soil ingestion HBLs. Soil ingestion HBLs assume 
direct contact with the waste and, therefore, are more conservative 
than HBLs based on inhalation exposures. In those instances when the 
waste concentrations exceeded both background levels and soil ingestion 
HBLs, we performed a third level screen using the results of EPA's air 
characteristics study. This study developed levels of chemical 
contaminants in wastes that are protective of human health with respect 
to inhalation exposures when managed in a variety of ways.\11\ In 
particular, air characteristic levels were developed for waste piles at 
several different distances from a potential receptor. We used the air 
characteristic levels corresponding to a downwind distance of 25 or 150 
meters (80 or 500 feet). Because the air characteristic levels include 
the effect of atmospheric dilution, they are significantly higher than 
soil ingestion HBLs. In most cases waste concentrations are either 
below background or below soil ingestion HBLs for the wastes EPA 
evaluated. Moreover, we found no instances in which air characteristic 
levels are exceeded. In the cases where waste concentrations exceeded 
the soil ingestion levels, the exceedence was typically less than a 
factor of 2 to 3. We believe it is highly unlikely that off-site 
exceedences due to windblown dust from piles or landfills would 
actually exceed the soil ingestion levels given this low level of 
exceedence in the waste. Therefore, we conclude that risks associated 
with particulates from piles and landfills transported by an air 
pathway are not significant and no further assessment is needed.
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    \10\ Different statistics may be used for characterizing 
background levels depending on the data available. The mathematical 
properties of the arithmetic mean allow it to be used when only 
average values rather than the original data are available. However, 
if the original data are available, the data can be pooled and a 
geometric mean can be calculated. If the data are positively skewed, 
as is often the case, the arithmetic mean will be higher than the 
geometric mean. We consider either statistic to be a central 
tendency measure of background levels. However, background levels 
are highly variable and may be considerably higher or lower than the 
national average at any given location. See, for example, the U.S. 
Geological Survey paper ``Elemental Concentrations in Soils and 
Other Surficial Materials in the Conterminous United States,'' paper 
1270, U.S. Government Printing Office, 1984.
    \11\ See U.S. EPA, ``Revised Risk Assessment for the Air 
Characteristic Study,'' Office of Solid Waste, EPA 530-R-99-019, 
November 1999.

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[[Page 55697]]

    EPA derived HBLs for chemical contaminants from toxicity benchmarks 
and a set of exposure assumptions that differ depending on the type of 
health effect and exposure pathway. For carcinogenic effects, HBLs were 
derived from a cancer slope factor (CSF) for the oral route of 
exposure. For non-cancer effects, HBLs were derived from EPA's oral 
reference dose (RfD) for the compound. Risk thresholds were as 
described previously. Drinking water and soil ingestion HBLs for 
individual chemical contaminants are presented elsewhere.\12\ The 
exposure assumptions we used for deriving the HBLs are described as 
follows.
---------------------------------------------------------------------------

    \12\ See the risk assessment background document for today's 
proposal, ``Risk Assessment for the Listing Determinations for 
Inorganic Chemical Manufacturing Wasters'' (August 2000).
---------------------------------------------------------------------------

    For drinking water exposures, we derived HBLs for carcinogenic 
effects for an adult exposed for 30 years and having a tap water intake 
of 1.4 liters per day. This represents 21 milliliters per day on a per 
kilogram body weight basis, which is the mean tap water intake for 
adults. A duration of exposure of 30 years represents the 95th 
percentile of the distribution of residential occupancy periods for 
adults nationwide. We derived HBLs for non-cancer effects for a child 
having a tap water intake of 1.3 liters per day. This represents 64 
milliliters per day on a per kilogram body weight basis and corresponds 
to the 90th percentile of the distribution of tap water intakes in 
children that are 1 to 10 years of age.\13\ Because the drinking water 
HBLs incorporate conservative exposure assumptions, we consider them to 
be appropriate for screening purposes.
---------------------------------------------------------------------------

    \13\ See EPA's ``Exposure Factors Handbook'' (EPA/600/P-95/
002Fa), August 1997, for additional details on human exposure 
factors.
---------------------------------------------------------------------------

    Soil ingestion HBLs were derived from either the CSF or the RfD 
assuming a soil ingestion rate of 200 milligrams per day and an 
exposure duration of 8 years. A soil ingestion rate of 200 milligrams 
per day (about 3/100th of a teaspoon) is a conservative estimate of the 
mean intake rates for children in the age range of 1 to 7. An exposure 
duration of 8 years is an estimate of the mean residential occupancy 
period for a 6 year old child. In selecting these values for use in 
deriving soil ingestion HBLs, we considered the likelihood that 
children would actually come into direct contact with the wastes.
    In cases where wastes are known to be managed in on-site landfills 
or surface impoundments that are located adjacent to or in close 
proximity to surface waters, we used additional screening criteria to 
identify wastes that could have the potential to adversely impact 
surface waters before eliminating the wastes from further 
consideration. We used EPA's national water quality criteria for this 
purpose. Specifically, we compared waste concentrations (i.e., SPLP 
measurements for wastes managed in on-site landfills and SPLP filtrate 
measurements for wastes managed in surface impoundments) directly to 
ambient water quality criteria that have been established for the 
protection of both human health and aquatic life. Any chemical 
contaminant in a waste managed under these circumstances that did not 
screen out against ambient water quality criteria (within a factor of 
2) we identified as a constituent of concern (CoC) requiring further 
assessment.
    EPA recently republished ambient water quality criteria for a large 
number of chemical contaminants (see 63 FR 68354; December 10, 1998). 
Separate criteria for the protection of aquatic life have been 
established for fresh water and salt water. In a number of instances 
waste management units are located adjacent to estuarine environments. 
In these cases, for screening purposes, we used the lower of the fresh 
water and salt water criteria.
4. How Was the Groundwater Pathway Evaluated?
    We conducted modeling analyses to assess possible risks to human 
health from wastes managed in land-based units such as landfills and 
surface impoundments. We used fate and transport models to estimate 
contaminant concentrations that might occur in a residential drinking 
water well from migration of uncontrolled releases of leachate from a 
waste management unit through the subsurface environment. We assessed 
human exposures to these contaminants from information on the amount of 
tap water an individual drinks and the length of time an individual 
might reside at a residence and utilize water from a residential well. 
We then assessed what the human health risks would be as a consequence 
of such exposures.
    We took a probabilistic approach to the assessment of human 
exposures. In this approach, we used Monte Carlo simulation techniques 
to determine the distribution of groundwater concentrations to which an 
individual could be exposed and combined this with distributional data 
for the general population on the intake rates of tap water and the 
duration of exposure. We then assessed the risks to human health from 
both the middle (central tendency) and upper (high end) portions of the 
distribution of human exposures. EPA defines high end as the 90th 
percentile and greater of the distribution of exposures in the 
population. Central tendency generally refers to the mean or 50th 
percentile of the distribution. Central tendency and high end estimates 
may be generated using either probabilistic or deterministic 
approaches.\14\
---------------------------------------------------------------------------

    \14\ We relied upon the probabilistic risk estimates for today's 
proposal. However, both deterministic and probabilistic approaches 
are presented in the risk assessment background document.
---------------------------------------------------------------------------

    We evaluated potential groundwater exposures over a 10,000 year 
time period. Evaluating peak doses over this time horizon allows the 
model to capture the slow movement of some chemicals through the 
subsurface. While exposure assumptions (e.g., land use patterns, 
climate, environmental and other exposure assumptions) are expected to 
change over 10,000 years, such changes are difficult to predict. We 
believe such a time period is appropriate to ensure human health is 
protected. Even with long time periods, we are still concerned with the 
risk that would result once contamination reaches potential drinking 
water wells. Given that the metals of concern do not degrade in the 
environment, we believe a long modeling time period is necessary. 
Further, there is uncertainty in when peak concentrations at the 
receptor well may occur, and using the 10,000 year time frame makes it 
more likely that we will capture the peak risk in our evaluation. EPA 
has used similar time horizons for groundwater modeling in past 
hazardous waste rules. \15\
---------------------------------------------------------------------------

    \15\ See HWIR proposal at 64 FR 63429, November 19, 1999, and 
the final rule for the recent listing of wastes from petroleum 
refining at 63 FR 42157, August 6, 1998.
---------------------------------------------------------------------------

    For modeling chemical concentrations in ground water, many input 
parameters were varied. These included waste characterization data 
(e.g., chemical concentrations and waste volumes), waste management 
practices (e.g., waste management unit size and infiltration rates), 
hydrogeological parameters (e.g., depth to water table, hydraulic 
conductivity, and aquifer thickness), and chemical parameters (e.g., 
soil-water partition coefficient). We conducted extensive sensitivity 
analyses to determine which of these parameters had the greatest 
influence on the risk results. For a detailed discussion of the ground 
water analysis, including parameter distributions, input assumptions, 
and sensitivity analyses, see the risk assessment background document 
for today's proposal, ``Risk Assessment for the Listing Determinations 
for Inorganic Chemical Manufacturing Wastes'' (August 2000).

[[Page 55698]]

    In assessing groundwater exposures for wastes managed in off-site 
landfills, we considered the locations of every industrial and 
municipal landfill known to receive the wastes and the volume of wastes 
managed at each of these sites. In so doing, we considered only that 
volume of waste that is currently not being managed as hazardous waste. 
For wastes managed on-site by multiple facilities, we generally 
considered only those facilities where groundwater exposures are 
expected to be the highest. These locations were identified by 
considering the concentration levels of chemical constituents in the 
waste managed at the site and the proximity of on-site waste management 
units, namely landfills and surface impoundments, to potential off-site 
receptors. Our rationale for selecting particular locations for 
conducting modeling analyses is discussed in section III.F for the 
specific inorganic sectors.
    a. How were contaminant concentrations in groundwater modeled? For 
modeling fate and transport in the subsurface environment, we used the 
groundwater model EPACMTP (EPA's Composite Model for Leachate Migration 
with Transformation Products). The model consists of two coupled 
modules: (1) A one-dimensional module that simulates infiltration and 
dissolved contaminant transport through the unsaturated zone, and (2) a 
three-dimensional saturated zone flow and transport module. Fate and 
transport processes accounted for in the model are advection, 
hydrodynamic dispersion, sorption equilibria, hydrolysis, and dilution 
from recharge to the saturated zone. The model assumes that the soil 
and aquifer are uniform porous media. EPACMTP (as used in this 
analysis) does not account for heterogeneity of the aquifer or for 
preferential migration pathways such as fractures and macro-pores or 
for colloidal transport, any or all of which could be important at a 
particular site. Although EPACMTP simulates steady-state groundwater 
flow in both the unsaturated zone and the saturated zone, the model (as 
used in this analysis) simulates contaminant transport from a finite 
source and predicts the peak contaminant concentration arriving at a 
down-gradient groundwater well. Only migration of chemical contaminants 
within the surficial aquifer is modeled by EPACMTP. We did not model 
migration of contaminants to deeper aquifers but, instead, based our 
assessment on exposures that might occur from groundwater withdrawn 
from the uppermost aquifer where contaminant concentrations are 
expected to be the highest.
    Equilibrium sorption of chemical contaminants onto soil and aquifer 
materials is parameterized in the EPACMTP model using a soil-water 
partition coefficient (Kd). For today's proposed rule, we used values 
for Kd that have been derived from field studies and have been 
published in the scientific literature. An empirical distribution was 
used to characterize the variability of Kd for chemical contaminants 
for which sufficient published data were available. However, for 
several chemical contaminants having relatively few published values 
(e.g., antimony and thallium), a log uniform distribution was used.\16\ 
Our use of empirically derived partition coefficients assumes that 
sorption is linear with respect to groundwater concentration (i.e., the 
Kd isotherm is linear). However, sorption is not unlimited and will 
tend to level off as groundwater concentrations increase beyond the 
linear range (i.e., the Kd isotherm becomes non-linear). This condition 
is most likely to occur in the unsaturated zone where dilution is 
limited, if leachate concentrations are sufficiently high.
---------------------------------------------------------------------------

    \16\ A log uniform distribution is a distribution that has equal 
probabilities at all percentiles when the parameter is transformed 
into logarithms. For these chemical constituents, we used a log 
uniform distribution that was centered on the geometric mean of the 
available data and had a width of 3 logs. This was done to better 
account for the variability normally seen in measurements of Kd.
---------------------------------------------------------------------------

    EPA has sometimes used the MINTEQA2 equilibrium speciation model to 
estimate Kd's for a variety of metals rather than relying solely on 
field measurements. However, recently a number of technical issues have 
been raised concerning the model and its application. EPA is in the 
process of evaluating the model to address those issues. Therefore, we 
have decided not to use MINTEQA2 for today's proposed rule. Once the 
evaluation is completed and the issues are satisfactorily resolved, EPA 
may again choose to use the model in an appropriate form in future 
rulemakings.
    Infiltration of leachate from landfills into the subsurface is 
modeled using the HELP model (Hydrologic Evaluation for Landfill 
Performance), a quasi-two-dimensional hydrologic model used to compute 
water balances for landfills. We assumed that landfills have a final 
earthen cover but no liner or leachate collection system. The net 
infiltration rate that is calculated by the model considers, among 
other factors, precipitation, evapotranspiration, and surface runoff 
and depends on the type of soil and the climate where the landfill is 
located. For surface impoundments, the infiltration rate is estimated 
from the liquid depth in the impoundment and from the hydraulic 
conductivities and thicknesses of the sediments and the underlying 
soil. We assumed that surface impoundments have no liner or leachate 
collection system. Unconsolidated or loose sediments are treated as 
free liquid so that the pressure head on the underlying, consolidated 
sediments is determined by the depth of the liquid in the impoundment 
and the depth of the unconsolidated sediments. As sediment accumulates 
at the base of the impoundment, the weight of the liquid and upper 
sediments acts to compress (or consolidate) the lower sediments. The 
result is the formation of a consolidated sediment layer having a 
hydraulic conductivity that is much lower than the previously 
unconsolidated sediment.
    We assumed that landfills have an operational life of 30 years.\17\ 
In landfills, leaching of contaminants from the waste leads to an 
exponential decrease in the leachate concentration with time. The rate 
at which this occurs depends on the volume of waste disposed of in the 
landfill and the total concentration of chemical contaminants in the 
waste. We used the measured TCLP concentration (for disposal in a 
municipal landfill) or SPLP concentration (for disposal in an 
industrial landfill) as the initial leachate concentration for 
modeling. In contrast, we assumed that surface impoundments have an 
operational life of 50 years.\18\ Many surface impoundments are 
periodically dredged and, therefore, can be maintained in service for 
longer periods of time. With surface impoundments, leachate 
concentrations are not expected to decrease over time and, therefore, 
leachate concentrations are assumed to remain constant during their 
operational life. We used the total concentration of chemical 
contaminant measured in the wastewater or (for wastewaters with high 
levels of solids) the concentration measured in the SPLP filtrate as 
the leachate concentration for modeling.
---------------------------------------------------------------------------

    \17\ U.S. Environmental Protection Agency, ``Draft National 
Survey of Solid Waste (Municipal) Landfill Facilities,'' Office of 
Solid Waste, Washington, D.C., 1988 (EPA/530-SW-88-034).
    \18\ See assumptions made for the recent proposed hazardous 
waste identification rule at 64 FR 63382; November 19, 1999.
---------------------------------------------------------------------------

    The fate and transport simulation modules in EPACMTP are linked to 
a Monte Carlo module to allow quantitative consideration of variability

[[Page 55699]]

and uncertainty in groundwater concentrations due to variability and 
uncertainty in model input parameters. We use a regional site-based 
methodology to associate the appropriate regional climatic and 
hydrogeologic conditions to the location of actual waste management 
sites. This methodology accommodates dependencies between the various 
model input parameters. In this approach, a site location is assigned 
to one of 13 hydrogeologic regions and one of 97 climatic regions that 
are linked to databases of climatic and hydrogeologic parameters. A 
climatic data set provides infiltration and recharge values for three 
soil textures at each of 97 climatic centers in the contiguous United 
States. The soil textures are based on a Soil Conservation Service soil 
mapping database and U.S. Department of Agriculture definitions of 
coarse, medium, and fine soil textures. (These textures are represented 
in EPACMTP by sandy loam, silt loam, and silty clay loam, 
respectively.) Infiltration rates for the waste management unit and the 
recharge rate for the surrounding region were determined for each soil 
type and climatic center using the HELP model. A site location is 
generally assigned to the climatic center that is geographically 
closest to the site.
    Each site location is also located on a groundwater resource map 
(from a U.S. Geological Survey inventory of State groundwater resource 
maps) and a hydrogeologic region is assigned to the site based on the 
primary aquifer type at that location. A hydrogeologic database 
provides a distribution of values for depth to groundwater, aquifer 
thickness, hydraulic gradient, and hydraulic conductivity for each of 
13 hydrogeologic regions. The hydrogeologic data base (HGDB) was 
developed from a survey of hydrogeologic parameters for approximately 
400 hazardous waste sites nationwide. These site-specific data were 
then regrouped according to hydrogeologic classifications, and a 
distribution of parameter values was generated for each of the 13 
hydrogeologic regions (made up of 12 specific hydrogeologic 
environments and one miscellaneous category). In the analysis for 
today's rule, we modified the above approach for on-site waste 
management units to enable available site-specific information on depth 
to groundwater to be used in place of the values found in the database.
    We also used a regional site-based methodology to associate the 
appropriate soil characteristics to a given site location. In this 
approach, a distribution of soil textures at a site is determined by 
associating the site location with a soils classification region. We 
defined soil classification regions from information on the soil types 
found within a 100 mile radius of the site location. The distribution 
of soil textures for the region was determined by identifying the soil 
texture classifications from data contained in the U.S. Department of 
Agriculture (Natural Resources Conservation Service) STATSGO (State 
Soil Geographic) data base. The predominant soil textures within each 
mapping unit (which represents a collection of soils) were identified 
and the fraction of the three soil textures used in the EPACMTP model 
were determined (i.e, sandy loam, silt loam, and silty clay loam). 
These soil classification regions were used for modeling off-site 
municipal and industrial landfill sites. A similar approach was taken 
for on-site landfills and surface impoundments except that the 
predominate soil textures from mapping units that correspond to the 
site location itself were identified. These were compared for 
consistency with other soils information available for the site. Once 
the fraction of the three soils textures is determined for a given site 
location, a distribution of soil parameter values is generated from 
information on the distribution of soil parameter values for the three 
soil textures and the fraction of each soil texture for the site. These 
parameters are used for modeling groundwater flow and contaminant 
transport in the unsaturated zone and include saturated conductivity, 
moisture retention properties, water content, and organic matter 
content.
    A full description of the groundwater modeling analyses conducted 
for today's proposed rule may be found in the background document, 
``Risk Assessment for the Listing Determinations for Inorganic Chemical 
Manufacturing Wastes'' (August, 2000).
    b. How were human exposures assessed? Our assessment of human 
exposures to contaminated ground water is based on a residential 
drinking water scenario. A different approach was used for determining 
the location of exposure depending on whether the wastes are managed 
on-site or are shipped off-site for disposal. For waste shipped to off-
site municipal landfills, we used EPA's National Survey of Municipal 
Landfills \19\ to determine the distance from the landfill to the 
receptor well. We also used these same data for off-site industrial 
landfills. For wastes managed on-site in either landfills or surface 
impoundments, we attempted to determine the closest point at which a 
residential well could be located and, therefore, the point at which 
human exposures could plausibly occur. We considered the location of 
the facility property boundary, the type of land use adjacent to the 
property boundary, the presence of surface waters that could intercept 
ground water flow, utilization of ground water for residential or 
agriculture uses, and the existence of residential drinking water wells 
in the direction of ground water flow. For both on-site and off-site 
waste management, we assumed the receptor well was located down-
gradient from the waste management unit and that ground water is 
withdrawn from the top ten meters of the aquifer and within the lateral 
extent of the contaminant plume. Exposures were further assumed to 
occur out to a distance of a mile from the waste management unit.
---------------------------------------------------------------------------

    \19\ Ibid.
---------------------------------------------------------------------------

    Our assessment of human exposures did not consider naturally 
occurring background levels in ground water. Background levels in 
ground water are not a significant source of human exposure for several 
of the more important chemical constituents in the wastes that are the 
subject of today's proposal (e.g., antimony and thallium). However, for 
manganese, dietary exposures are a significant source of background 
exposures. We did not attempt to quantify the cumulative risks from 
both dietary and drinking water exposures combined and, therefore, this 
is a source of uncertainty in our assessment of risks from manganese in 
these wastes.
    Human exposures were characterized in terms of lifetime average 
daily dose (LADD) and average daily dose (ADD) for both children and 
adults. We used the LADD for assessing cancer risks and the ADD for 
assessing risks from non-cancer effects (including reproductive, 
developmental, neurological, cardiovascular, hematologic, metabolic, 
and a wide variety of other physiologic effects). Exposures to children 
of age one to six years and adults of age 20 to 64 years were assessed. 
We used information from EPA's Exposure Factors Handbook \20\ to 
characterize tap water intake rates for individuals and residential 
occupancy periods of households (and, therefore, the length of time an 
individual could be exposed to contaminated ground water). 
Distributional data on tap water intake rates for individuals and 
residential occupancy periods for households were

[[Page 55700]]

used to generate both the ADD and LADD exposure estimates. For 
assessing lifetime exposures, we averaged the well water concentrations 
over the duration of exposure (i.e., the residential occupancy period). 
We also averaged the tap water intake rates over the duration of 
exposure to account for the changes in tap water intake rates with age 
that are seen among children. For estimating the ADD, we used the peak 
9-year average well water concentration but did not further average the 
estimated exposure (which we believe would be inappropriate given the 
range of possible health effects we want to protect against). Previous 
work with the EPACMTP ground water model has shown that the peak 9-year 
concentration and the maximum predicted concentration are nearly 
identical.
---------------------------------------------------------------------------

    \20\ U.S. Environmental Protection Agency, ``Exposure Factors 
handbook'', Volumes I and III, Office of Research and Development, 
National Center for Enironmental Assessment, Washington, DC., August 
1997 (EPA/600/P-95/002Fa and c).
---------------------------------------------------------------------------

    A full description of the methods and data used in the exposure 
assessment for today's proposed rule may be found in the background 
document, ``Risk Assessment for the Listing Determinations for 
Inorganic Chemical Manufacturing Wastes'' (August, 2000).
5. How Was the Surface Water Pathway Evaluated?
    A number of facilities that generate wastes covered by today's 
proposed rule are located adjacent to rivers or bays. As a consequence, 
the potential exists for subsurface releases of chemical contaminants 
from on-site management of the wastes to enter these river and bay 
systems through ground water inflow. In instances where no direct 
contact with ground water is likely to occur (as there would otherwise 
be if, for example, ground water was being used for residential 
drinking water), it becomes important to evaluate the potential water 
quality impacts of these releases on surface waters in the context of 
hazardous waste listings. However, we wish to emphasize that the 
surface water impacts considered in today's proposed rule are due to 
subsurface releases to ground water only. Direct discharges to surface 
waters are already regulated by the Clean Water Act under the NPDES 
permit system and are not considered further in today's proposal.\21\
---------------------------------------------------------------------------

    \21\ Industrial wastewater discharges that are regulated under 
the National Pollutant Discharge Elimination System (NPDES) Permit 
Program are specifically excluded from regulation as hazardous 
wastes under 40 CFR 261.4(a)(2).
---------------------------------------------------------------------------

    We conducted a screening level analysis to evaluate potential 
surface water impacts. In this analysis, we estimated the volume of 
leachate that would infiltrate into ground water and assumed that this 
entire volume would be intercepted by surface water. Because this is a 
screening analysis, we made conservative assumptions that are likely to 
overstate the infiltration of leachate and, therefore, the potential 
release to surface water. For example, for on-site landfills, we 
assumed a soil type (sandy loam) that is likely to overstate the 
infiltration rate even in the absence of liners or leachate collection 
systems. Similarly, for surface impoundments we assumed a sludge 
thickness (8 inches) and soil type (sandy loam) that is likely to 
overstate the infiltration rate. In addition, we assumed no retardation 
in the migration of chemical contaminants in ground water due to 
sorption or other processes.
    Due to the nature of these releases, which are likely to occur over 
a wide area, we assumed that the inflow of contaminated ground water 
was rapidly diluted into surface water and that there was little or no 
mixing zone. We followed EPA's Office of Water guidance for determining 
the design flows for rivers as regards water quality criteria. The 
appropriate design flow depends on the particular water quality impact 
being evaluated. For assessing potential impacts on aquatic life, we 
used the ``7Q10'' as the design flow. The 7Q10 is the seven day low 
flow with a return frequency of once every 10 years and is the 
recommended design flow for use with chronic water quality criteria for 
the protection of aquatic life. We believe that chronic water quality 
criteria are the appropriate criteria for evaluating the potential 
impact of continuing steady releases, such as those that would result 
from subsurface discharge of contaminated ground water. On the other 
hand, EPA generally uses the ``30Q5'' as the design flow for assessing 
potential impacts on human health. The 30Q5 is the thirty day low flow 
with a return frequency of once every 5 years and is the recommended 
design flow for use with water quality criteria for the protection of 
human health as regards non-cancer effects. However, a 30Q5 design flow 
was not available in all cases. In these instances, we estimated the 
30Q5 based on the 7Q10 design flow.\22\ For carcinogens (e.g., 
arsenic), lifetime exposures are the primary concern and a design flow 
that corresponds to a longer averaging time is appropriate. For this 
reason, EPA recommends the long-term harmonic mean be used as the 
design flow.\23\ The harmonic mean is always less than the arithmetic 
mean and is used in place of it because low flow conditions drive long-
term average water quality. However, because this flow statistic was 
not available, we estimated the harmonic mean flow from the arithmetic 
mean flow and the 7Q10.
---------------------------------------------------------------------------

    \22\ EPA guidance provides a simple rule of thumb for estimating 
the 30Q5 from the 7Q10 depending on the size of the river. For 
smaller rivers (defined as those with a low flow of 50 cfs or less), 
the 30Q5 is 1.1 times the 7Q10. For larger rivers (low flow of 600 
cfs or greater), the 30Q5 is 1.4 times the 7Q10. See ``Technical 
Support Document for Water Quality-Based Toxics Control,'' EPA/505/
2-90-001, March 1991.
    \23\ The harmonic mean is defind as the inverse of the average 
of the sum of the inverses of the recorded flows.
---------------------------------------------------------------------------

    As a result of the screening level analysis, all wastes screened 
out for which the ground water to surface water pathway was a concern. 
Therefore, no additional analysis of this pathway was conducted.
6. What Are the Limitations and Uncertainties of the Assessment?
    Our assessment of exposures and risks is subject to a variety of 
limitations and uncertainties. These are discussed in some detail in 
the background document for today's proposed rule. A number of these 
are highlighted here.
    We assumed our sampling and analysis data are fully representative 
of the range of wastes generated in the effected industries. However, 
our own data show that there are significant variations in waste 
concentrations across facilities in a given industry. Variability in 
waste concentration that is unaccounted for could lead to an over- or 
under-estimation of risks. However, any tendency toward under-
estimation is likely to be mitigated to some extent by our selection of 
wastes and exposure scenarios that are intended to capture the highest 
risks.
    We also assumed that our methods for measuring the leaching 
behavior of wastes (i.e., the TCLP and SPLP test procedures) are both 
representative of the range of leaching conditions that exist under 
real world conditions and accurately quantify the concentrations of 
contaminants that leach into the subsurface environment from a given 
waste management unit. However, we know that many metals exhibit 
varying (or amphoteric) behavior with respect to pH and that any one 
test procedure is capable of characterizing leaching behavior only 
under a particular set of conditions.
    The ground water model we used in our analysis (i.e., EPACMTP) is 
designed to characterize dilution and attenuation in the subsurface 
environment under homogeneous conditions. The model does not account 
for subsurface heterogeneities, nor does it account for fractured flow 
or colloidal transport. These conditions, if present at

[[Page 55701]]

a site, can lead to less dilution and attenuation of contaminant levels 
than predicted by the model, causing ground water concentrations to be 
under estimated. In addition, sorption of metal species onto soil and 
aquifer materials exhibits considerable variability depending on 
geochemical conditions and the total concentration of the metal present 
at a given location. Although our use of empirically derived Kd values 
captures some of this variability, the available published data are 
fairly limited for certain metals (e.g., antimony). We have accounted 
for the uncertainty associated with the small number of data points 
explicitly for these metals by expanding the range of Kd values used 
for modeling (to three orders of magnitude). Even for metals that have 
abundant data (e.g., arsenic), it is unlikely that the range of 
variability apparent in the data could exist at a given site.
    Uncertainty associated with the specification of Kd as noted above 
could lead to an over- or under-estimation of risk. However, a tendency 
toward over-estimation is likely to be mitigated by the fact that under 
near steady-state conditions (when ground water impacts are the 
greatest), concentrations in ground water are little influenced by Kd. 
Under non-steady conditions, any tendency toward over- or under-
estimation is limited by the variability inherent in the empirical 
distributions of Kd used in the analysis, which include both relatively 
high and relatively low values of Kd. Nevertheless, in general the risk 
estimates are sensitive to the specification of Kd and, therefore, this 
is an important source of uncertainty in our analysis.
    As indicated previously, for wastes managed on-site we based our 
assessment of human exposures on the plausibility of ground water being 
used for drinking water. While some information was available on 
utilization of ground water for drinking water, very limited 
information was available from which to determine the location of 
exposure at a given site. For wastes managed off-site we assumed that 
ground water is used for drinking water (or will be in the future) and 
we used national data on the distribution of distances to residential 
wells to assess human exposures and risk. Our analysis did not consider 
possible changes in the location of on-site waste management operations 
in the future. These exposure assumptions (about which there is 
considerable uncertainty) may have an impact on the estimated risks 
and, therefore, the outcome of the risk assessment.
    Other important uncertainties include those related to the health 
effects of chemical contaminants in humans (hazard identification), 
absorption and metabolism of ingested contaminates (pharmacokinetics), 
and biological response (dose-response relationships). These and other 
limitations and uncertainties are discussed in the background document, 
``Risk Assessment for the Listing Determinations for Inorganic Chemical 
Manufacturing Wastes'' (August, 2000).

F. Sector-Specific Listing Determination Rationales

    We seek comments on all proposed listing decisions in this section, 
and the underlying rationales used to support our proposals.
1. Antimony Oxide
    a. Summary. We have evaluated antimony oxide production wastes and 
propose to list two wastes from this process as hazardous: (1) Baghouse 
filters and (2) slag that is disposed of or speculatively accumulated. 
We propose to list the baghouse filter waste under the criterion in 40 
CFR 261.11(a)(1) because it routinely exhibits one or more of the 
characteristics of hazardous waste, but the waste is not consistently 
managed in compliance with Subtitle C regulations. We propose to list 
the slag under the criteria in 40 CFR 261.11(a)(3) because of risks 
associated with land disposal.

K176  Baghouse filters from the production of antimony oxide. (E)
K177  Slag from the production of antimony oxide that is disposed of or 
speculatively accumulated (T).

    Other wastes generated by the antimony oxide industry do not meet 
the criteria set out at 40 CFR 261.11(a)(3) for listing a waste as 
hazardous. They do not pose a substantial present or potential threat 
to human health or the environment. We identified no risks of concern 
associated with the current management of these other wastes.
    b. Description of the antimony oxide industry. Antimony oxide was 
produced by four facilities in the United States in 1998. Antimony 
oxide is used as a flame retardant in plastics and textiles, a smoke 
suppressant, a stabilizer for plastics, an opacifier in glass, ceramics 
and vitreous enamels, and a coating for titanium dioxide pigments and 
chromate pigment.
    The manufacturers use two different processes to produce antimony 
oxide. In the first process, antimony metal is roasted in the presence 
of air. The antimony oxide forms as a fume, cools and condenses in a 
baghouse. In the second process, crude (low grade) antimony oxide is 
roasted in the presence of air to produce higher grade antimony oxide. 
The antimony oxide cools and condenses in a baghouse. The crude 
antimony oxide comes either from off-site or is recycled from within 
the facility.
    c. How does the Bevill Exclusion apply to wastes from the antimony 
oxide manufacturing processes? Antimony oxide producers use a range of 
raw materials to produce antimony oxide, including antimony metal 
ingots, sodium antimonate, and antimony ore concentrate, and some 
facilities have claimed that wastes generated from the production of 
antimony oxide are Bevill exempt. Wastes generated from processes using 
either antimony ingots or sodium antimonate (both of which are saleable 
mineral products) are considered chemical manufacturing wastes rather 
than mineral processing wastes and are not eligible for the Bevill 
exemption. The September 1, 1989 Bevill final rule states at 54 FR 
36620-21 that chemical manufacturing begins if there is any further 
processing of mineral product.
    Two of the facilities also purchase an antimony ore concentrate as 
a raw material and place this material in kilns to produce antimony 
oxide. The smelting of a ore concentrate above the fusion point is 
defined as mineral processing (See 54 FR 36618). At these antimony 
oxide facilities, since mineral processing has begun, wastes from the 
process are not eligible for the Bevill exemption as beneficiation 
wastes (See 40 CFR 261.4(b)(7)(i)). In addition, although there is a 
Bevill exemption for 20 specific mineral processing wastes form various 
mineral processing sectors, the wastes generated from antimony oxide 
mineral processing are not included as one of these 20 wastes and are 
not excluded. (See 40 CFR 261.4(b)(7)(ii)). Thus there are no antimony 
oxide wastes that qualify for the Bevill exemption.
    d. Wastes generated by these processes. Table III-1 summarizes our 
information about the wastes generated from the production of antimony 
oxide:

[[Page 55702]]



                                 Table III-1.--Antimony Oxide Production Wastes
----------------------------------------------------------------------------------------------------------------
                                      Number of
          Waste category              reported     1998 volume      Reported waste        Management practices
                                     generators       (MT)           hazard codes
----------------------------------------------------------------------------------------------------------------
Antimony slag not recycled in                  3           113  D008.................  Sent to lead smelters for
 process.                                                                               lead and/or antimony
                                                                                        recovery; or on-site
                                                                                        drum storage prior to
                                                                                        future on-site land
                                                                                        disposal.
Baghouse filters..................             4             9  No code reported.....  In-process antimony
                                                                                        recovery; off-site
                                                                                        antimony recovery;
                                                                                        industrial Subtitle D
                                                                                        landfill; or non-
                                                                                        hazardous waste
                                                                                        incinerator.
Empty supersacks..................             1            15  No code reported.....  Disposal in off-site
                                                                                        Subtitle D landfill or
                                                                                        recycled.
----------------------------------------------------------------------------------------------------------------

    In addition to these wastes, there are other materials produced 
that are reused in the antimony oxide production process. Antimony 
oxide and antimony slag are captured at various points in the facility 
and reinserted into a furnace to produce antimony oxide, either on-site 
or off-site. Because these materials are managed prior to reuse in ways 
that present low potential for release, and because we evaluated 
process waste generated after the secondary materials are reinserted 
into the process, we do not believe that these secondary materials 
present significant risks.
    e. Agency evaluation. (1) Antimony slag not recycled in antimony 
oxide process.
How Are These Wastes Currently Managed?
    Three facilities produced antimony slag that is not recycled in the 
antimony oxide process. Two of these facilities send the slag to lead 
smelters. One of the two facilities reported its slag to be TC 
hazardous because of its lead content (D008). The third facility, 
however, has historically stored a portion of its slag on-site in 
drums, reporting that they plan to reclaim antimony when antimony 
prices are more favorable. Recent revisions to the facility's Operating 
Permit,\24\ however, require that the slag be placed in an on-site 
engineered ``slag storage pit'' to be constructed in the next two to 
three years.
---------------------------------------------------------------------------

    \24\ ``United States Antimony Corp. Stibnite Hill Mine Project 
Operating Permit 00045'', 6th review draft, January 1999. This draft 
permit is issued under the Metal Mine Reclamation Act, 82-4-301 MCA. 
It was prepared by the facility, approved by the State of Montana on 
August 12, 1999 (with a number of stipulations), and subsequently 
approved by the Forest Service.
---------------------------------------------------------------------------

    We assessed the on-site disposal scenario, reflecting the projected 
management practice for this waste. For a number of years, the facility 
has been placing approximately 20 MT/yr in steel drums on pallets on 
the ground. The facility reported that they intend to reclaim the 
antimony from this slag when antimony prices are favorable. We consider 
storage on-site for more than one year to be speculative accumulation 
and consider these materials to be solid wastes. We believe that the 
length of time secondary materials are accumulated before being 
recycled is an important indicator of whether or not they are wastes. 
This is supported by the large number of recycling damage cases where 
secondary materials that were overaccumulated over time caused 
extensive harm. (See 50 FR 614) ``Under RCRA and the implementing 
regulations, permanent placement of hazardous waste, including 
perpetual ``storage'' falls into the regulatory category of land 
disposal.'' \25\ (See also American Petroleum Institute v. EPA, 216 F. 
3d 50 (D.C. Cir. 2000).) Since the Operating Permit requires the 
facility to build and use an on-site, land-based unit for this waste, 
we assessed the on-site landfill scenario for this waste.
---------------------------------------------------------------------------

    \25\ ``Above Ground Land Emplacement Facilities, N.J. Law,'' 
Letter to Honorable James J. Florio, Chairman, Subcommittee on 
Commerce, Transportation, and Tourism, Committee on Energy and 
Commerce, House of Representatives, from J. Winston Porter, 
Administrator, EPA, dated March 26, 1986.
---------------------------------------------------------------------------

How Was This Waste Category Characterized?
    We selected two of the three facilities for sampling and analysis. 
At the site which stores the slag indefinitely, we collected one sample 
of ``reduction furnace slag'' that was designated as containing less 
than 5 percent antimony (AC-1-AO-01) and one sample of ``reduction 
furnace slag'' that was designated as containing between 5 and 10 
percent antimony (AC-1-AO-06). Based on characterization information 
provided by the facility in its RCRA Section 3007 Survey response, we 
believe these samples are representative of all of the slags generated 
at the facility. We conducted total, TCLP and SPLP analyses of these 
slags. The analytical results for the constituents found to be present 
in the leachates at levels exceeding the HBLs are presented in Table 
III-2.
    We collected a third sample (LI-1-AO-01) at a facility that 
reclaims its slag for lead. This sample failed the TC for lead, as the 
facility reported in its RCRA Section 3007 Survey response. The results 
are available in ``Waste Characterization Report, Laurel Industries 
Inc., La Porte, Texas'' in the docket for today's proposal.

                                        Table III-2.--Characterization of Speculatively Accumulated Antimony Slag
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                         AC-1-AC-01                               AC-1-AO-06
                                                          ---------------------------------------------------------------------------------
                  Constituent of concern                    Total  mg/                              Total  mg/                                HBL  mg/L
                                                                kg       TCLP  mg/L   SPLP  mg/L        kg       TCLP  mg/L    SPLP  mg/L
--------------------------------------------------------------------------------------------------------------------------------------------------------
Antimony.................................................       11,500         55.8         114        127,000         110           211          0.006
Arsenic..................................................          301          2.0           2.9          478           3.1           3.8        0.0007
Boron....................................................          500          9.8           9.3        2,500           8.5           8.1        1.4
Selenium.................................................           50          0.6           0.6          250           0.6           0.3        0.08
Vanadium.................................................           50          1.3           1.1          250           0.6           1.0        0.14
--------------------------------------------------------------------------------------------------------------------------------------------------------


[[Page 55703]]

How Was the Groundwater Ingestion Risk Assessment Established?
    We modeled the annual volume reported to be stored on-site 
indefinitely (20 MT). (The facility reports that it processes sodium 
antimonate from two facilities and returns the resultant slag to the 
process for further processing. We did not include these recycled slag 
volumes in our modeling.)
    We used the total and SPLP results as model inputs, reflecting the 
industrial nature of the on-site unit. We used only the analytical 
results for the facility that stores the slag indefinitely. Both of the 
samples for this facility are relevant because they represent the 
material stored on-site and destined for the on-site slag pit. We did 
not model the sample from the other sampled facility because they 
acknowledged that their waste exhibited the TC. Both this facility and 
the facility that was not sampled reclaim these wastes in a manner that 
is excluded from regulation under Subtitle C. We believe that it is 
reasonable to assume that they will continue to manage their slags in 
ways that do not violate Subtitle C regulations. Also, in this case, 
the SPLP results are higher than the TCLP results, making the 
industrial landfill the worst case scenario.
    We examined records available from the State where the slag is 
stored to determine the appropriate distance-to-well to model. We 
identified four residential wells within several miles of the facility. 
These data demonstrate that groundwater is a viable and actively used 
resource in this area. One well is located 1.4 miles directly 
downgradient. Based on local topography and groundwater information, we 
do not believe the other identified wells could be affected by releases 
to groundwater from the facility. We modeled potential releases to a 
downgradient residential well. Given that our groundwater model is not 
configured at this time to model releases further than one mile, we did 
not assess the full distance to the known well. In our probabilistic 
analysis, we varied the well distance from the closest property 
boundary that appeared to be potentially downgradient to the limit of 
the model (one mile). Our results therefore are conservative with 
respect to this particular well, but otherwise reflect the fact that 
future residences and wells may be placed closer to the facility and 
any potential groundwater plumes associated with its operation. 
Specifically, we modeled potential distances to wells from the 
facility's southern boundary to one mile.
    We used a regional site-based approach in modeling this unit, as 
described in section III.E.4. We modified this to enable us to use 
available depth to groundwater information at this particular site.
What Is EPA's Listing Rationale for This Waste?
    Where these slags are reused and present no exposure route of 
concern, we did not evaluate these secondary materials further.
    The results of the risk assessment for the on-site disposal 
scenario for boron, selenium, and vanadium were very low. In the 90th 
to the 95th percentile range, the highest hazard quotient for these 
three constituents was in the range of 0.001. For this reason, the full 
results for these three constituents are not presented here. The 
results of the risk assessment for the on-site disposal scenario for 
antimony and arsenic are presented in Table III-3:

         Table III-3.--Probabilistic Risk Assessment Results for Speculatively Accumulated Antimony Slag
----------------------------------------------------------------------------------------------------------------
             Percentile                Adult risk    Child risk         Adult risk              Child risk
----------------------------------------------------------------------------------------------------------------
                                          \1\Antimony hazard
                                               quotient
                                        \1\Arsenic--cancer risk
----------------------------------------------------------------------------------------------------------------
90th%...............................           2.2           4.6  4 E-07                  3 E-07
95th%...............................           4.5           9.4  1 E-06                  9 E-07
----------------------------------------------------------------------------------------------------------------

For a more complete description of this analysis, see ``Risk Assessment 
for the Listing Determinations for Inorganic Chemical Manufacturing 
Wastes'' (August 2000) in the docket for today's proposal.
    In our modeling results, the dilution and attenuation factors 
(DAFs) were relatively high. For example, high end antimony DAFs were 
as high as 8,000. This is the result of the hydrogeological setting of 
the site evaluated. Due to the high hydraulic conductivity we used in 
modeling, the landfill leachate is readily diluted into a large volume 
of groundwater. Given the uncertainty about the actual ultimate 
management practice and the site-specific nature of the modeling, DAFs 
could be considerably lower in other disposal scenarios, resulting in 
much higher hazard quotients and, therefore, higher potential risks.
    Our modeling approach assumes that the slag will be placed in an 
unlined unit. Information from the facility, however, indicates that 
they plan to place the waste in an on-site lined storage pit, upon 
completion of construction, that will be governed by a state mining 
permit. We considered whether our decisionmaking should account for the 
added protection provided by a liner system. Our first consideration is 
the current uncertainty regarding this waste's disposition. While the 
facility has stated its intended placement of this waste in a lined 
unit, our most recent information indicates that construction had not 
yet begun. The facility may in fact choose to place this waste in an 
off-site commercial landfill that would not necessarily be lined. This 
uncertainty is greater than in most waste management scenarios that we 
have assessed in this rulemaking, where there is a long term history of 
management in a particular type of management unit (e.g., an operating 
on-site landfill, a local off-site landfill). Because of this 
uncertainty, we are hesitant to give much weight to a liner system that 
may be constructed in the future.
    More generally, we considered the efficacy of landfills (and any 
liners) over the modeled risk assessment period, which covers 10,000 
years. Landfills are used actively until their capacity is reached (our 
models assume an active life of 30 years), and at the end of their 
active life, we assume landfills are closed and the wastes remain in 
the unit indefinitely. The effectiveness of liner systems depends on 
how they are designed. Composite and double liners that combine two or 
more layers of liner material with leachate collection and leak 
detection will no doubt minimize leakage to the subsurface during the 
period when the leachate collection system is actively managed. 
However, depending on the regulatory controls relevant for a particular 
unit, monitoring would continue for a limited post-closure period. 
There is also uncertainty associated with liner performance, in the 
near term as well as in the long term. There are a variety of factors 
that may influence longevity and performance, such as poor 
construction, installation

[[Page 55704]]

or facility operation, or geologic movement below the liner that can 
cause holes, tears or larger failures. Some defects may have a 
significant effect. Because of our uncertainty regarding the efficacy 
of the liner system over long periods of time, and the uncertainty over 
the ultimate disposal for this waste, we believe our use of the 
modeling results for an unlined landfill is appropriate.
    In deciding whether to list this waste as hazardous, we also 
considered other factors in addition to the risk results noted above. 
First, we considered the very high levels of toxic constituents present 
in the waste and in test leachate (which is one of the criterion cited 
in 261.11(a)(3)(ii)). The levels of antimony and arsenic are quite 
high. The antimony level exceeds 10% in the waste (up to 127,000 mg/
kg), and the SPLP antimony concentration exceeds the drinking water HBL 
by a factor of >35,000. Another key factor is the lack of any 
appreciable degradation expected for these metals (a constituent's 
degradation or persistence is also a criterion for listing given in 
261.11(a)(3)). Unlike some organic compounds, metals such as antimony 
will not degrade over time. Thus, even if the loss in effectiveness of 
a liner system only occurs over the very long term, the metals would 
still be present for leaching. It is difficult to assess the impact of 
the long-term effectiveness of the liner system in question for today's 
proposal. However, we note that the effectiveness of the liner system 
would have to be sufficient to reduce the antimony concentration at the 
well by close to 90% in order to keep the risks below an HQ of 1.
    Therefore, given the reasons cited above, we propose to list these 
slags as hazardous:

K177  Slag from the production of antimony oxide that is disposed of or 
speculatively accumulated.
    It is important to note that this listing has been developed to 
capture only those wastes that are not recycled. Thus, this listing, as 
proposed, would not apply to generators that recycle or reclaim this 
material as long as it is not speculatively accumulated. If slags have 
been speculatively accumulated (i.e., held for more than a calendar 
year without recycling) at the time of the effective date of this final 
rule, these slags would meet the listing immediately.\26\
---------------------------------------------------------------------------

    \26\ A material is not accumulatively speculatively, however, if 
the person accumulating it can show that the material is potentially 
recyclable and has a feasible means of being recycled and that--
during the calendar year (commencing on January 1)--the amount of 
material that is recycled or transferred to a different site for 
recycling equals at least 75 percent by weight or volume of the 
amount of that material accumulated at the beginning of the period. 
(40 CFR 261.1(c)(8))
---------------------------------------------------------------------------

    We also propose to add antimony to Appendix VII to Part 261, which 
designates the hazardous constituents for which K177 would be listed.
    (2) Baghouse filters.
How Are These Wastes Currently Managed?
    These filters capture product or off-specification product. Two 
facilities place antimony laden baghouse filters in their on-site 
production furnaces. One of these facilities also sends a portion of 
its baghouse filters to Mexico for antimony recovery. Two other 
facilities dispose of these wastes in a non-hazardous waste incinerator 
and an industrial Subtitle D landfill. None of these wastes are handled 
as hazardous, although our sampling efforts showed this waste to 
exhibit the toxicity characteristic for lead and arsenic.
How Was This Waste Category Characterized?
    We collected a total of three samples of this waste category from 
two facilities. At one facility we collected one sample of the 
``oxidation furnace'' baghouse filters (AC-1-AO-03) and one sample of 
the ``reduction furnace'' baghouse filters (AC-1-AO-07). At the other 
facility, we collected a sample of the baghouse associated with its 
kiln (LI-1-AO-03). Because the facilities sampled represented the range 
of production practices within the industry, we believe these samples 
are representative of all of the baghouse filters generated by this 
industry. We conducted total, TCLP and SPLP analyses of these baghouse 
filters. The analytical results for the constituents found to be 
present in the leachates at levels exceeding the HBLs are presented in 
Table III-4. Two of the three samples of the waste, one from each 
facility that generate this waste, exceed the toxicity characteristic 
for either lead or arsenic. (The third sample exhibits TCLP lead levels 
close to the TC standard).

                            Table III-4.--Characterization of Baghouse Filters From Antimony Oxide Production (mg/kg or mg/L)
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                     LI-1-AO-03                    AC-1-AC-03                    AC-1-AO-07                        TC
          Constituent of Concern           ------------------------------------------------------------------------------------------    HBL   ---------
                                              Total     TCLP      SPLP      Total     TCLP      SPLP      Total     TCLP      SPLP                Limit
--------------------------------------------------------------------------------------------------------------------------------------------------------
Antimony..................................    91,400       9.3       6.2   150,000       9.9       4.3   145,000      68.7       287     0.006  ........
Arsenic...................................       114       0.5       0.6       250       0.5      0.09       250   \1\ 6.9       6.9    0.0007       5.0
Boron.....................................      24.0       6.5       1.0      2500         2       0.2      2500         2       0.7       1.4  ........
Cadmium...................................       5.3       0.3       0.5       250       0.3       0.3       411      0.05       0.9    0.0078       1.0
Lead......................................       3.1   \1\ 8.5      16.9      2500       2.8       1.0       250       0.5      0.05     0.015       5.0
Mercury...................................       0.9     0.002     0.001       0.1     0.002    0.0002      95.2      0.03       0.4    0.0047       0.2
Thallium..................................         2         2      0.06      1000         2      0.06      1000         2       0.1    0.0013  ........
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Exceeds Toxicity Characteristic level.

What Is EPA's Listing Rationale for This Waste?
    We propose to list the baghouse filters waste because our data show 
it routinely exhibits one or more of the characteristics of hazardous 
waste (i.e., TC lead or arsenic), yet the generators do not identify 
their wastes as exhibiting the toxicity characteristic and the 
generators that dispose of this waste do not comply with Subtitle C 
regulations. We propose to list this waste under the 261.11(a)(1) 
criteria:

K176 Baghouse filters from the production of antimony oxide (E).

    Because we believe we have sufficient reason to list this waste 
under 261.11(a)(1) based on the TC exceedences and lack of compliance 
with hazardous waste regulation, we chose to conserve our time and 
resources and did not conduct formal risk assessment modeling of the 
off-site landfill scenario, as we would traditionally do to support a 
261.11(a)(3) listing. Such modeling would reflect reported management 
practices. Antimony is not a TC constituent and, therefore, was not 
considered in the 261.11(a)(1) listing decision. However, antimony 
levels are high and would likely result in risk if modeled. Leach 
results for the waste exceed the HBLs by

[[Page 55705]]

a wide margin, e.g., the SPLP results for antimony are up to 48,000 
times the HBL. The high levels of antimony in the waste (up to 15%) 
would provide a long-term source of the metal for leaching into the 
groundwater. Thus, we expect that modeling an off-site Subtitle D 
scenario would yield significant drinking water risk.
    Note that, when facilities process the antimony oxide product 
captured in these filters by reinserting the product-containing filters 
back into the furnace where the antimony oxide originated, without 
reclamation, these materials would not be solid wastes.\27\
---------------------------------------------------------------------------

    \27\ As noted above, these filters capture product materials. 
EPA does not regulate reclamation of these products. See 50 FR 
14216, April 11, 1985: ``Under the final rules, commercial chemical 
products and intermediates, off-specification variants, spill 
residues, and container residues listed in 40 CFR 261.33 are not 
considered solid wastes when recycled except when they are recycled 
in ways that differ from their normal use--namely, when they are 
burned for energy recovery or used to produce a fuel''
---------------------------------------------------------------------------

    We also propose to add arsenic and lead to Appendix VII to Part 
261, which designates the hazardous constituents for which K176 would 
be listed.
    The ``mixture'' rule for listed wastes currently provides an 
exemption for wastes listed solely because they exhibit characteristics 
(see 40 CFR 261.3(a)(2)(iii)). Mixtures of such listed wastes lose 
their listed waste status when they cease to exhibit characteristics 
for which they were listed. (However, they would still need to comply 
with Land Disposal Restriction requirements.) In the both of the last 
two Hazardous Waste Identification Rule (HWIR) proposals (60 FR 66344, 
December 21, 1995) and (64 FR 63382, November 19, 1999), we proposed to 
narrow the exemption to only include wastes listed for ignitability, 
corrosivity, and reactivity.
    This narrowing would make any waste listed for the toxicity 
characteristic (TC) (including the waste proposed today for listing 
under the (a)(1) criteria) ineligible for the current exemption. In 
other words, under current mixture rule regulations, mixtures 
containing these baghouse filters would become nonhazardous wastes once 
they ceased exhibiting the characteristic. Under the HWIR proposal, 
however, such mixtures would remain hazardous wastes even after they 
cease to exhibit the TC. As we state in the TC rule, chemicals can 
still pose hazardous at levels below the TC (see 55 FR 11799, March 29, 
1990). Under an amended consent decree (Environmental Technology 
Council v. Browner, C.A. No. 94-2119 (TFH), April 11, 1997), EPA is 
required to sign a notice taking final action with respect to the 
proposed revisions to the mixture rule by April 30, 2001.
    (3) Empty supersacks. One facility ships crude antimony oxide in 
supersacks and then reuses them to store intermediate materials until 
they wear out. The facility then sends these empty supersacks either to 
an off-site industrial Subtitle D landfill or to an off-site plastic 
recycler. The facility claims that the supersacks are empty and would 
meet the standard in 40 CFR 261.7 (which exempts ``empty'' containers 
formerly used to manage hazardous waste). Although 40 CFR 261.7 does 
not literally apply to these sacks, we think it is reasonable to take a 
similar approach here. We believe that the levels of crude antimony 
oxide in worn-out supersacks would be low because the material is the 
primary feedstock (raw material) used in this process. We do not 
believe it follows that these supersacks should be regulated, when 
other similarly empty containers would be exempt. Therefore, we propose 
not to list this waste as hazardous.
2. Barium Carbonate
    a. Summary. We have evaluated the wastes, waste management 
practices, and potential risk exposure pathways associated with the 
barium carbonate production processes and propose not to list any 
wastes from this industry as hazardous under Subtitle C of RCRA. Some 
wastes in this industry are D002 or D005 characteristic hazardous 
wastes, which are both currently subject to RCRA Subtitle C regulation 
and managed in compliance with those regulations. For other wastes, not 
identified as characteristic hazardous wastes, we have identified no 
risks of concern associated with the current management of these wastes 
that would warrant listing. These wastes do not meet the criteria 
listed under 40 CFR 261.11(a)(3) for listing a waste as hazardous.
    b. How is barium carbonate produced? There are two facilities in 
the United States that produce significant quantities of barium 
carbonate. A Georgia facility produces barium carbonate for commercial 
sale. A Pennsylvania facility produces barium carbonate only for use as 
a feedstock in its own internal manufacturing processes. A third 
facility is a specialty manufacturer that produces extremely small 
amounts of barium carbonate (approximately 10 kg in 1998).\28\ For more 
detailed information concerning this industry, see ``Barium Carbonate 
Listing Background Document for the Inorganic Chemical Listing 
Determination'' in the docket for today's proposal.
---------------------------------------------------------------------------

    \28\ Since, as explained below, we find no significant risks 
from the larger volume wastes we assessed, we conclude that any low 
volume wastes from this third facility also would not pose any risks 
warranting listing.
---------------------------------------------------------------------------

    Barium carbonate (BaCO3) has a wide range of uses, 
including feedstock for production of other barium chemicals, an 
additive in various glasses, ceramics, bricks, and other construction 
materials, an additive in oil-drilling suspensions, and a brine 
purification chemical in the chlor-alkali industry.
    The two primary barium carbonate production facilities use 
different manufacturing processes to make barium carbonate. The Georgia 
facility uses locally mined barite ore, containing barium in the form 
of barium sulfate, as the primary feedstock. The ore is crushed and 
milled, thermally reduced in a roasting kiln, and leached with water to 
dissolve the barium. The resulting barium sulfide solution is filtered 
and reacted with carbon dioxide gas to produce a barium carbonate 
precipitate. This precipitate is then dried, and sized for sale.
    The Pennsylvania facility uses a commercially purchased high purity 
barium chloride solid as the primary feedstock. The facility dissolves 
the barium chloride in water, heats and filters the resulting solution, 
and precipitates barium carbonate by reacting the barium chloride 
solution with ammonium bicarbonate. The resulting barium carbonate 
precipitate is washed, filtered, dried and sized before the facility 
utilizes it as a feedstock in other manufacturing processes on-site.
    c. What wastes are generated? Table III-5 below briefly lists the 
facility-reported residuals from the barium carbonate manufacturing 
processes, residual volumes generated in 1998, reported RCRA hazard 
codes, and residual management practices.

[[Page 55706]]



                                Table III-5.--Barium Carbonate Production Wastes
----------------------------------------------------------------------------------------------------------------
                                                              Reported RCRA hazard       Sequential residual
           Waste category               1998 volume (MT)              codes              management practices
----------------------------------------------------------------------------------------------------------------
                                 Barite Ore Feedstock Process--Georgia Facility
----------------------------------------------------------------------------------------------------------------
Treated barium wastes (D005 barium   18,300................  None (D005 prior to     Disposal in local, captive,
 wastes include barite ore leaching                           treatment).             industrial Subtitle D
 waste, barium sulfide filtration                                                     landfill (after treatment
 sludge, and barium carbonate                                                         of D005 wastes in on-site
 production area cleaning and                                                         Subtitle C treatment
 maintenance wastes).                                                                 unit).
Wastewater from BaCO3 precipitate    313,000...............  None..................  Treatment in on-site, tank-
 dewatering.                                                                          based WWTP prior to NPDES
                                                                                      discharge to Etowah River.
WWTP sludge........................  11,000................  None..................  (1) Dewatered;
                                                                                     (2) Treated on-site;
                                                                                     (3) Disposal in local,
                                                                                      captive, industrial
                                                                                      Subtitle D landfill.
Spent polypropylene and nylon        3 (filter media)......  None..................  (1) Washed and washwaters
 filter media and baghouse dust      1.5                                  re-inserted to barium
 collector bags.                      (baghouse bags).                                carbonate production
                                                                                      process. Solids managed as
                                                                                      barium carbonate
                                                                                      production area cleaning
                                                                                      and maintenance wastes.
                                                                                     (2) Treated materials
                                                                                      disposed in off-site
                                                                                      municipal Subtitle D
                                                                                      landfill.
----------------------------------------------------------------------------------------------------------------
                      High Purity Barium Chloride Feedstock Process--Pennsylvania Facility
----------------------------------------------------------------------------------------------------------------
Ammonia vapor scrubber water and     Not reported..........  D002..................  Treatment in on-site, tank-
 ammonia reclamation unit                                                             based WWTP.
 wastewaters.
Barium carbonate precipitate         1,600.................  None..................  Treatment in on-site, tank-
 washwater.                                                                           based WWTP prior to NPDES
                                                                                      discharge to Susquehanna
                                                                                      River.
WWTP sludge........................  8,200.................  None..................  (1) Stored in roll-off bin;
                                                                                     (2) Disposal in off-site
                                                                                      municipal Subtitle D
                                                                                      landfill.
Ammoniated spent process solution    1.....................  None..................  Disposal in off-site
 storage tank solids.                                                                 municipal Subtitle D
                                                                                      landfill.
Sludge and spent filter media from   1.23..................  D005..................  (1) Stored in closed
 filtration of barium chloride                                                        container;
 solution and BaCO3 drying and                                                       (2) Sent to off-site
 sizing unit dusts.                                                                   Subtitle C facility for
                                                                                      treatment and disposal.
----------------------------------------------------------------------------------------------------------------

    In addition to these wastes, the two barium carbonate manufacturing 
facilities also produce other materials which are either piped directly 
back to the production process or are used for other purposes. Residues 
from the barite ore feedstock production process, ore crusher/grinder, 
kiln, barium carbonate drier, granulation and packaging processes are 
directly returned to their unit of origin with no significant pathways 
for exposure of these materials to the environment prior to reuse. 
Barium carbonate production area cleaning and maintenance wastewaters 
are also re-inserted to the barium carbonate production process with no 
significant pathways for exposure of these materials to the environment 
prior to reuse. Because these materials are managed prior to reuse in 
ways that present low potential for release, and because we evaluated 
all wastes generated after they are reinserted into the process, we do 
not believe that these secondary materials present significant threats.
    The barite ore feedstock facility also produces molten sulfur or 
sodium hyposulfate from hydrogen sulfide gas piped from the barium 
carbonate manufacturing process. Because the material is a gas from a 
production unit, rather than from a waste management unit, and is 
conveyed to its destination through piping, the gas is not a solid 
waste. RCRA Section 1004(27) excludes non-contained gases from the 
definition of solid waste, and therefore they cannot be considered a 
hazardous waste (see 54 FR 50973).
    The facility using barium chloride as its feedstock reclaims 
ammonia in the form of ammonium hydroxide from barium carbonate 
production wastes and uses this material throughout the facility as a 
feedstock and reagent. Spent ammoniated process solution is piped from 
the process unit where it forms to a storage tank where it is 
commingled with ammoniated spent process solutions from several other 
on-site manufacturing processes. The ammoniated spent process solutions 
from these other manufacturing processes are beyond the scope of this 
listing determination. From the storage tank, the facility pipes the 
commingled ammoniated spent process solutions to an ammonia reclamation 
unit which reclaims the ammonia in the form of ammonium hydroxide. 
Ammonium hydroxide is used on-site in various manufacturing processes, 
including the production of ammonium bicarbonate solution for use in 
the barium carbonate production process. Because the spent solution is 
piped to the reclamation unit with no significant potential for 
exposure to the environment, we did not evaluate the solution further.
    Both facilities produce barium carbonate from a saleable mineral 
product.\29\ Under the Bevill exemption (54 FR 36620-21), chemical 
manufacturing begins if there is any further processing of a saleable 
mineral product. Since these facilities use saleable mineral products 
as feedstock, their processes are chemical manufacturing, and are not 
classified as mineral processing. Therefore none of the wastestreams 
generated by these facilities during the production of barium carbonate 
are Bevill exempt.
---------------------------------------------------------------------------

    \29\ Note that primary barite ore has wide use in drilling muds 
for the petroleum industry and numerous other industrial uses, 
including use as feedstock for barium chemicals; see ``Barite'' U.S. 
Geological Survey--Minerals Information, 1997, http://minerals.usgs.gov/minerals/pubs/commodity/barite/index.htm.
---------------------------------------------------------------------------

    See the ``Barium Carbonate Listing Background Document for the 
Inorganic Chemical Listing Determination'' for more details on these 
residuals.

[[Page 55707]]

    d. Waste characterization and Agency evaluation. Barium is the 
primary constituent of potential concern in the wastes from both 
facilities. Barium occurs in several production wastes at high levels, 
in some cases exceeding the TC level (100 mg/L) in TCLP leachate 
samples. These TC wastes are coded and treated as hazardous (D005). The 
Georgia facility holds a hazardous waste treatment permit to allow on-
site stabilization of barium, and the Pennsylvania facility sends all 
of their D005 wastes off-site for treatment and disposal at a hazardous 
waste treatment and disposal facility.
    We decided not to do characterization sampling for wastes from 
either facility because both facilities submitted information to us on 
the nature of their wastes. We also received some additional analytical 
data from the State of Georgia for the Georgia facility. These data 
provided information on the concentrations (or absence) of the metal 
constituents of potential concern in the wastes and in test leachates 
from the wastes. We believe the available information is sufficient to 
adequately characterize the wastes and to allow us to evaluate their 
risk potential for the purposes of a listing decision. ``Barium 
Carbonate Listing Background Document for the Inorganic Chemical 
Listing Determination'' summarizes the analytical data and other 
information available for these wastes.
    We propose not to list any of the wastes from the barium carbonate 
manufacturing industry. Many wastes from this industry are 
characteristically hazardous and managed as hazardous wastes either on-
site or at permitted Subtitle C treatment facilities off-site. Other 
wastes did not exhibit constituents at levels of concern for purposes 
of a listing given the nature of their management and disposal.
    Several groups of wastes from each of the facilities are disposed 
of in a treated form, rather than an as-generated form. In general, 
therefore, we focused our evaluation on the treated form of the wastes.
    The paragraphs below describe how the wastes are generated and 
managed for the two processes and our rationale for proposing not to 
list the wastes. We solicit comments on the proposed listing decisions 
described below.
    (1) Wastes from the production of barium carbonate from barite ore 
feedstock. (a) Treated barium wastes. The waste category, ``treated 
barium wastes,'' is the treatment residue from the commingling and 
treatment of several barium wastes in an on-site hazardous waste 
treatment unit. The barium wastes, which are consistently 
characteristically hazardous for barium (D005) before treatment (or are 
consistently assumed by the facility to be D005 wastes), include:

--Barite ore leaching waste, which is solids from the filtration of the 
liquid product stream from the barite ore roasting and leaching units,
--Barium sulfide sludge, which is from polishing filtration of liquid 
barium sulfide, and,
--Wastes from cleaning and maintenance of the barium carbonate 
production area.

    A RCRA Subtitle C hazardous waste treatment facility permit governs 
the on-site treatment process for these barium wastes. The three wastes 
are sent directly to the treatment unit, or they are stored prior to 
treatment for short time periods in Subtitle C closed containers. The 
treatment process is a stabilization process for barium using gypsum 
(primarily calcium sulfate) to precipitate soluble barium as less 
soluble barium sulfate. According to RCRA Subtitle C regulations, the 
treated barium waste must meet the LDR UTS. Treatment takes place in 
concrete mixer-type trucks. Once treatment is complete, the treatment 
trucks immediately transport the waste to the facility's captive 
Subtitle D landfill for disposal, located approximately 2 miles from 
the production facility on facility-owned property.
    State and facility information indicate that the treated barium 
wastes no longer exceed the TC level for barium (100 mg/L from TCLP 
analysis) and typically leach less than 1 mg/L barium, according to 
both SPLP and TCLP analyses. In addition, according to data the 
facility and the state of Georgia submitted to EPA from sampling events 
conducted during the past two years at the facility, the waste meets 
the LDR UTS for all regulated constituents.
    The treated barium wastes are disposed of in the landfill without 
daily cover. However, the waste has a relatively high moisture content 
(approximately 50%) when placed in the landfill and, according to the 
facility, hardens over time and does not create dust. In addition, the 
waste does not contain any known volatile constituents of concern.
    To assess the potential for groundwater releases from the captive, 
industrial landfill, we compared the SPLP leaching data from the 
facility and the state of Georgia to existing HBLs for ingestion of 
groundwater. SPLP data are appropriate for evaluating this waste 
because it is placed in a Subtitle D industrial landfill. We did not 
find any constituents in the available SPLP data that exceeded the 
health-based levels by more than a factor of 2 (see section III.E.3 for 
a discussion of this risk-screening criterion). See the ``Barium 
Carbonate Listing Background Document for the Inorganic Chemical 
Listing Determination'' for further details on the available data.
    In addition, we found only one exceedence of AWQC standards among 
the SPLP leaching data for treated barium wastes. Selenium was found at 
a level of 0.04-0.06 mg/L, which exceeds the AWQC standard (0.0050 mg/
L) by a factor of 8 to 12. However, the landfill in which the treated 
barium wastes are placed is 1,700 feet from the nearest downgradient 
water body, the Etowah River, and also lies beyond the river's 100 year 
flood plain. In recent years, the Etowah River in the vicinity of the 
landfill has had a flow rate varying between 9.9 to 230 m 3 
per second on a daily basis. Given the distance over which leachate 
from the treated barium wastes would need to travel before reaching the 
river, dilution and attenuation during transport in local groundwater, 
and further dilution in the Etowah River, we believe the levels of 
selenium in the leachate would decrease to a level which would no 
longer pose a risk to the environment.
    We do not believe it is necessary to assess other management 
practices for the treated barium wastes. The facility has treated and 
disposed of their treatment residues in a similar manner for over 15 
years. The production facility itself relies on a local source of 
barite ore, has operated from its current location since 1942 and is 
therefore not likely to change its location in the near future. The 
dedicated landfill has a remaining life of nearly 20 years and is 
located approximately 2 miles from the production facility. Given the 
dedicated nature of the landfill, its proximity to the production 
facility, and the significant remaining capacity, we believe it is 
unlikely that the Georgia facility will dispose of their wastes in any 
other unit in the near future. Thus there is no need to assess 
additional management scenarios for this wastestream.
    Given the facility's Subtitle C waste treatment permit, we believe 
that the facility's untreated D005 wastes are adequately managed with 
respect to this rulemaking. In addition, we have found no potential for 
releases to air, groundwater, or surface water at levels of concern 
from the treated wastes. Therefore we propose not to list these wastes.
    (b) Wastewater from barium carbonate precipitate dewatering. The 
facility filters barium carbonate precipitate from

[[Page 55708]]

residual process solutions and sends this filtrate to the facility's 
tank-based wastewater treatment plant (WWTP) for treatment. According 
to the facility's RCRA Section 3007 Survey response, the wastewater 
does not exceed the TC level for any constituent.
    Wastewater from the barium carbonate production process commingle 
in the WWTP with wastewaters from other facility processes beyond the 
scope of this rulemaking and comprise approximately 17% of the total 
WWTP flow-through. The wastewater treatment is an oxidation process. 
Treatment of the wastewaters occurs in tanks equipped with secondary 
containment. Given the controlled manner in which the wastewater is 
managed in tanks, the lack of any volatile constituents of concern, and 
NPDES regulation of the WWTP effluent, we propose not to list this 
wastewater.
    (c) Treated wastewater treatment plant sludge. The facility's WWTP 
generates a treatment sludge from the commingling and treatment of 
wastewaters discussed above in the preceding section. The resulting 
sludge is dewatered to 25% solids content in an uncovered tank. None of 
the information the facility provided on this waste indicates the 
presence of volatile constituents of concern.
    The facility places the dewatered WWTP sludge directly from the 
WWTP unit into a treatment unit consisting of a concrete mixer-type 
truck containing gypsum (primarily calcium sulfate). The truck mixes 
the wastewater treatment sludge with the gypsum to convert soluble 
barium to a less soluble barium sulfate prior to transporting the waste 
to the facility's off-site, captive, Subtitle D landfill. We found low 
potential for releases from either the dewatering tank or the treatment 
unit. Analytical data from the state shows that the treatment process 
reduced leachable barium in the sludge, according to SPLP analysis, 
from 53 mg/L to 0.03 mg/L.
    SPLP analytical data from the State also show no potential 
constituents of concern in treated WWTP sludge samples at 
concentrations above HBLs or above AWQCs. Therefore, this waste 
screened out from any further risk evaluation for groundwater or 
surface water. The SPLP data are appropriate for evaluating this waste 
because it is placed in a Subtitle D industrial landfill.
    Similar to the treated barium wastes described above in section 
(a), the waste has a high moisture content when placed in the landfill 
and is reported by the facility to harden over time. Therefore, we do 
not believe this waste poses a significant risk through releases of 
airborne dust. In addition, the waste does not contain any known 
volatile constituents of concern.
    We do not believe it is necessary to assess other management 
practices for this waste. The facility has treated and disposed of 
their wastewater treatment plant sludge in a similar manner for over 15 
years. Given the dedicated nature of the landfill, its proximity to the 
production facility, and the significant remaining capacity, we believe 
it is unlikely that the facility will dispose of their wastes in any 
other facility in the foreseeable future.
    Based on our knowledge of the current nature of the management of 
the treated wastewater treatment plant sludge and of the low level of 
constituents of concern it contains, including volatile constituents, 
we propose not to list the treated wastewater treatment plant sludge.
    (d) Spent polypropylene and nylon filter media and baghouse dust 
collector bags. Baghouse dust collector bags and polypropylene and 
nylon filter media fabric at the Georgia facility deteriorate over time 
and must be replaced periodically. The facility washes the bags and 
filters with water and then soaks them in sulfate solution to stabilize 
any remaining barium. The facility then disposes of the bags and filter 
fabric in a local municipal Subtitle D landfill. Wastewaters from the 
washing of the filters and bags are returned to the production process. 
Solids from the washing of the filters and bags become part of the 
cleaning and maintenance wastes that are treated as discussed above in 
section (a).
    The facility did not provide chemical composition analyses for 
these wastes. However, we do not expect either baghouse bags or nylon 
and polypropylene filter fabrics, which are used primarily for physical 
separation of solids from liquids in the barium carbonate production 
process, to contain notable levels of any potential constituent of 
concern besides barium. According to the facility, neither the bags nor 
the filters exceed the TC level for any constituent. In addition, the 
facility treats the materials to stabilize any remaining barium before 
disposing of them in a Subtitle D municipal solid waste landfill. The 
facility does not produce a large volume of these wastes; approximately 
3 metric tons per year of filters and approximately 1.5 metric tons per 
year of baghouse bags. Because barium is not volatile, and because we 
do not expect the filter media and bags to contain any other volatile 
constituents, we do not believe these residuals pose any risk through 
airborne pathways.
    Given the relatively small volume of these wastes, the inert nature 
of the filters and bags themselves, and the facility's washing and 
stabilization of barium prior to disposal, we believe these treated bag 
wastes do not warrant listing as hazardous wastes.
    (2) Wastes from the production of barium carbonate from high purity 
barium chloride feedstock. (a) Barium carbonate production wastewaters 
and wastewater treatment plant sludge. The Pennsylvania facility 
commingles and treats wastewaters from several manufacturing processes 
at their facility in an on-site, tank-based WWTP. Wastewaters from the 
barium carbonate production process are piped directly to the WWTP and 
comprise less than 1% of total WWTP flow through; the remainder of the 
wastewaters entering the WWTP are from manufacturing processes not 
within the scope of this listing determination. Wastewaters from the 
barium carbonate production process include:

--Ammonia vapor scrubber waters and ammonia reclamation unit 
wastewater.
--Barium carbonate precipitate washwater.

    A scrubber captures ammonia vapor from the mixing of ammonium 
bicarbonate solution with the barium chloride solution to precipitate 
barium carbonate. Water, sodium hydroxide, and emissions from other 
manufacturing processes in the facility mix with the ammonia vapor in 
the scrubber to produce this wastestream.
    An ammonia reclamation unit recovers ammonia from ammoniated spent 
process solutions from multiple manufacturing processes, including the 
barium carbonate manufacturing process, in the form of 28% ammonium 
hydroxide solution. The unit also produces a wastewater. Approximately 
1% of the total ammonia reclamation unit inflow derives from the barium 
carbonate production process. Therefore, a small percentage of the 
unit's wastewater derives from barium carbonate production.
    The facility also produces a wastewater from the washing of barium 
carbonate precipitate with deionized water in order to remove any 
process solution remaining on the precipitate.
    The only possible release route of concern from the tank-based 
system for the wastewaters would be through air releases. This pathway 
is highly unlikely for the nonvolatile metals that are the potential 
constituents of concern in these wastes. Given the controlled manner in 
which the wastewaters are managed and the regulation of the

[[Page 55709]]

treatment unit's discharge under the NPDES program, we propose not to 
list these wastewaters.
    Treatment of the commingled wastewaters consists of neutralization 
followed by filtration. The treatment generates a sludge. According to 
the facility's RCRA Section 3007 Survey response, the sludge does not 
exceed the TC level for any constituent. The facility disposes of the 
sludge in a local Subtitle D municipal solid waste landfill. We do note 
the presence of some potential constituents of concern in the WWTP 
sludge. These constituents include vanadium, nickel, and antimony. 
However, we do not believe that these constituents derive from the 
barium carbonate manufacturing process.
    Because the barium carbonate production process wastewaters 
contribute less than 1% of the total input to the on-site WWTP, any 
constituents in the barium carbonate production wastewaters sent to the 
WWTP also make a minimal contribution to the total level of 
constituents in the combined wastewater in the WWTP and the resulting 
sludge. In addition, the process uses high purity barium chloride 
dissolved in deionized water as its primary feedstock and reclaims much 
of the residual ammonia from its ammonium bicarbonate feedstock. 
Therefore, the likelihood that the constituents of concern in the 
sludge might arise from the barium carbonate production process is very 
low. Moreover, the facility has provided information to us indicating 
that the barium carbonate process is not the source of these potential 
constituents of concern and that they derive instead from on-site 
manufacturing processes beyond the scope of today's listing proposal 
(see ``Barium Carbonate Listing Background Document for the Inorganic 
Chemical Listing Determination'' for further details). Given the 
minimal potential for contribution of constituents of concern by the 
barium carbonate process wastewaters to the WWTP sludge, we propose not 
to list this sludge under this rulemaking effort.
    (b) Ammoniated spent process solution storage tank solids. The 
facility pipes residual process solution containing ammonia directly 
from the barium carbonate precipitate settling unit to covered storage 
tanks prior to routing it through an on-site ammonia reclamation unit. 
The barium carbonate process wastewater is one of many ammoniated 
residual process solutions the facility routes to the storage tanks and 
constitutes approximately 1% of the unit's total input.
    The ammoniated spent process solution storage tank accumulates 
solids which the facility removes and disposes of in a local Subtitle D 
municipal solid waste landfill on a yearly basis. The tank solids are a 
small volume waste of 1 MT/yr. According to analytical data provided by 
the facility, the solids do not exceed the TC level for any 
constituent, though they do contain vanadium, nickel, and antimony at 
levels of potential concern. However, as noted for the wastewater 
treatment plant sludge, the constituents of concern in the solids are 
unlikely to arise from the barium carbonate production process because 
the barium carbonate production process contributes only 1% of the 
total wastewaters in the storage tanks. In addition, information the 
facility provided indicates that the nickel, vanadium and antimony 
found in the sludge derive from other manufacturing processes that are 
beyond the scope of this listing determination. Thus, given the solids' 
small volume and the low likelihood that the barium carbonate process 
wastewater contributes any constituents of concern, we propose not to 
list the ammoniated spent process solution tank solids in this listing 
determination.
    (c) Sludge and spent filter media from filtration of barium 
chloride solution and barium carbonate drying and sizing unit air 
pollution control residues. Both the air pollution control dusts from 
the barium carbonate drying and sizing unit and sludge and the spent 
filter materials from barium chloride solution filtration exceed the TC 
regulatory level for barium (100 mg/L). The facility codes the waste as 
characteristic hazardous waste (D005). The facility stores these small 
volume wastes in closed containers on-site before sending them to a 
RCRA Subtitle C hazardous waste treatment and disposal facility for 
treatment and disposal. We believe that the containers present no 
significant potential for release to the environment. We believe that 
regulations applying to characteristic wastes adequately protect 
against mismanagement. Furthermore, these wastes comprise a very small 
volume (1.23 metric tons per year). Thus, we propose not to list these 
wastes.
3. Boric Acid
    a. Summary. We have evaluated the wastes from the production of 
boric acid and propose not to list any wastes from this process as 
hazardous under RCRA. These wastes do not meet the criteria set out at 
40 CFR 261.11(a)(3) for listing wastes as hazardous. They do not pose a 
substantial present or potential threat to human health or the 
environment. We have identified no risks of concern associated with the 
current management of the wastes.
    b. Description of the boric acid industry. Boric acid was produced 
by two facilities in the United States in 1998. These two facilities 
are both located in the Mojave Desert in California, one of the few 
areas where borate minerals can be mined in the United States.
    The two facilities mine borates from different sources to produce 
boric acid. The first recovers borate from brines pumped from beneath 
Searles Dry Lake, California. The second facility mines sodium borate 
ores near Boron, California.
    The first facility extracts highly mineralized brine and uses a 
liquid-liquid extraction process to remove the borates from the brine. 
During the first production step, called the ``loading section,'' the 
facility mixes the brine with a chelating agent in a kerosene solution 
that causes most of the boron and some of the sodium and potassium 
compounds in the brine to bind to the extractant. The loaded extractant 
is sent through strippers where it is mixed with dilute sulfuric acid 
to strip the boron, sodium and potassium from the extractant to form 
boric acid, sodium sulfate and potassium sulfate. The solution is then 
sent to a solution settler from which the liquor goes to boric acid 
recovery using crystallization and evaporation techniques.
    The second facility mines sodium borate kernite ore to produce 
boric acid through a process of dissolution, classification, 
thickening, filtration and crystallization.
    Because the facilities use such different sources and production 
processes, their resulting wastes are very different and are discussed 
separately. For more detailed information concerning this industry, see 
the ``Boric Acid Background Document for the Inorganic Chemical Listing 
Determination'' in the docket for today's proposal.
    c. Agency evaluation of wastes generated by the brine recovery 
process.
Are There Any Wastes in This Process That Fall Under the Bevill 
Exemption?
    The depleted brine from the loading section of the brine recovery 
process is exempt as a mineral processing beneficiation waste under 40 
CFR 261.4(b)(7)(i).\30\ This waste from the

[[Page 55710]]

extraction/beneficiation of ores and minerals is thus outside the scope 
of the consent decree. The facility reported generating 4,600,000 MT in 
1998. This Bevill exempt waste is commingled with wastes which do not 
qualify for the Bevill exclusion later in the process. The portion of 
the waste which does not qualify for the Bevill exclusion is within the 
scope of the consent decree and is discussed below.
---------------------------------------------------------------------------

    \30\ The Agency has previously evaluated the Bevill status of 
wastestreams at the Searles Lake facility; see memos dated February 
14, 1992 and June 30, 1993 in Appendix E of the ``Boric Acid 
Background Document for the Inorganic Chemical Listing 
Determination'' in the docket.
---------------------------------------------------------------------------

    As discussed in the Agency's prior Bevill evaluations for this 
facility, mineral processing begins at the liquid-liquid extraction 
step where sulfuric acid is added to the loaded extractant to produce 
sodium sulfate and boric acid. Wastes generated before this step, 
including spent brine, are beneficiation wastes and retain their Bevill 
exemption. All wastes generated after the beginning of mineral 
processing are non-exempt solid wastes. Therefore, all of the wastes at 
this facility which are generated from the liquid extraction step to 
the end of the process are all non'exempt solid wastes. See the ``Boric 
Acid Background Document for the Inorganic Chemical Listing 
Determination'' in the docket for more information on the Bevill 
exemption for wastes at this facility.
What Kinds of Wastes Are Generated by the Brine Recovery Process?
    The Bevill exempt depleted brine from the loading section is sent 
through an API settler and Wemco floatation cells designed to separate 
organic compounds from the brine. The organic emulsions generated in 
these units and in the process settlers are sent to an on-site ``crud'' 
treatment facility which breaks down the emulsion into aqueous and 
organic components. This treatment process generates a non-exempt 
hydrocarbon waste (fuel oil) that is sent off-site to a used oil 
refinery. The Bevill exempt brine is sent to the ``Trona skimmer'' 
where it is combined with other non-exempt wastewaters generated during 
the process. The Trona skimmer acts as a settling pond promoting phase 
separation of remaining organic materials in the brine. The Bevill 
exempt brine is then returned to the dry lake for recharging as 
required by the facility's Bureau of Land Management permit. Because 
the non-exempt wastewaters are commingled with the Bevill exempt brine 
in the Trona skimmer, the non-exempt wastewaters are also returned to 
the dry lake as a small percentage of the overall volume. The non-
exempt organic waste removed at the Trona skimmer is stored on-site in 
a tank until it is shipped off-site to a commercial blender and 
subsequently burned for energy recovery.
    Additional wastes generated by the brine recovery process that are 
not Bevill exempt include:

--Petroleum contaminated sludges from containment areas around the API 
settler, Wemco floatation cells, loading section and liquid-liquid 
extraction (LLX) strippers
--Spent activated carbon collected from the carbon filter system used 
to purify the borate liquor before it goes into the crystallization 
units

    In addition to the above wastes, the facility also produces other 
materials during the production of boric acid that are either piped 
directly back to the production process or used for other purposes. 
These materials include aqueous residuals and kerosene recovered from 
the crud treatment process, off-specification product, scrubber water 
and condensate that are returned to on-site production units for use. 
Because these materials are reused on-site in production units and 
there is no significant potential for exposure of these materials to 
the environment prior to reuse, we found that they present no 
significant threat. Also, off-specification product, when reinserted 
without reclamation into the process where it originated, is not a 
solid waste.
How Are the Wastes From the Brine Recovery Process Currently Managed?
    Table III-6 summarizes our information about the wastes from this 
process:

        Table III.-6.--Boric Acid: Brine Recovery Process Wastes
------------------------------------------------------------------------
                                                         Sequential
       Waste category           1998 volume (MT)    management practices
------------------------------------------------------------------------
Fuel oil from crud treatment  690.................  (1) Stored in
 facility.                                           covered tank;
                                                    (2) Sent off-site to
                                                     a Subtitle C
                                                     permitted used oil
                                                     refinery.
Miscellaneous wastewaters...  194,040 (The Bevill   (1) Combined
                               exempt partially      wastewaters;
                               depleted brine        discharged to Trona
                               volume is 4.6         skimmer with the
                               million MT).          Bevill exempt
                                                     partially depleted
                                                     brine;
                                                    (2) Removal of
                                                     organics in skimmer
                                                     unit;
                                                    (3) Commingled
                                                     partially depleted
                                                     brine and process
                                                     wastewaters are
                                                     returned to Searles
                                                     Dry Lake for
                                                     recharging.
Organics from Trona skimmer.  10..................  (1) Stored in
                                                     covered tank;
                                                    (2) Sent to off-site
                                                     Subtitle C blender;
                                                    (3) Burned for
                                                     energy recovery.
Sludges from containment      20..................  (1) Drum storage;
 areas.                                             (2) 20 cubic yard
                                                     roll-off bins;
                                                    (3) Transported with
                                                     manifest off-site
                                                     to Subtitle C
                                                     landfill as
                                                     California-only
                                                     hazardous waste.
Spent activated carbon......  43..................  (1) Washed;
                                                    (2) Reclaimed in an
                                                     on-site furnace;
                                                    (3) Reused in the
                                                     process.
------------------------------------------------------------------------


[[Page 55711]]

What Is EPA's Decision About Whether to List These Wastes as Hazardous?
    We propose not to list any wastes from the brine recovery process 
for the production of boric acid. Our rationale for each waste is 
presented below.
    (1) Fuel oil from the crud treatment facility. We propose not to 
list the fuel oil generated at the crud treatment facility. The 
facility characterized the fuel oil as 100 percent hydrocarbons. The 
fuel oil is stored on-site in a covered tank prior to being shipped 
off-site to a Subtitle C permitted used oil refinery. For those 
scenarios where wastes are managed in a tank, the impervious nature of 
the construction materials (concrete, fiberglass, or steel) of tanks is 
unlikely to result in releases to groundwater in all but the most 
catastrophic scenarios. We also are not concerned with potential air 
releases because the tank is covered. The subsequent treatment at the 
permitted used oil refinery is already regulated under Subtitle C and 
the used oil regulations. Therefore, we propose not to list this waste.
    (2) Miscellaneous wastewaters. We propose not to list the 
miscellaneous wastewaters. We evaluated the potential for an exposure 
pathway via groundwater ingestion and determined that no such pathway 
exists. The facility producing boric acid by recovering borates mined 
from Searles Dry Lake is located in California's Mojave Desert. The 
process and associated wastewaters are tied to the Mojave Desert 
location because it is the source of the borate rich brine. The 
environment is arid with only 4 inches of precipitation annually. The 
groundwater under the facility has total dissolved solids (TDS) levels 
as high as 450,000 ppm. All wastewaters, including the Bevill exempt 
depleted brine, are co-managed and ultimately returned to the dry lake 
resource. Due to the extremely high TDS levels in the area, the water 
is non-potable. The surrounding communities have drinking water piped 
in from 25 miles away. Therefore, no groundwater exposure pathway 
exists.
    Furthermore, the total volume of the miscellaneous wastewaters is 4 
percent of the volume of the depleted brine; any contaminants in these 
wastewaters would therefore be diluted by a factor of 25 prior to 
return to the dry lakebed. Most of the miscellaneous wastewaters are 
generated in the later part of the process and thus we do not expect 
they will contain constituents of concern at significant levels. There 
is one wastewater that contains organic constituents not found in the 
influent brine (formaldehyde and fuel hydrocarbons). This wastewater is 
generated at the carbon column. However, it only represents 0.03 
percent of the total volume that is returned to the dry lake. Also, the 
reported level of formaldehyde in the waste would be well below the HBL 
for this chemical (3 mg/L) \31\ after mixing with other wastewaters. We 
are not concerned with potential air releases because the Trona 
skimmer, where the wastes are mixed, is covered. The facility also 
mixes a characteristic (D002) HCl acid waste stream with the Bevill 
exempt depleted brine prior to reaching the Trona skimmer. The 
resultant mixture is not characteristic and the mixing takes place 
within a pipeline where there is no opportunity for exposure to the 
characteristic waste before or during the mixing. Given the factors 
listed above, particularly the lack of an exposure pathway, we propose 
not to list the miscellaneous wastewaters.
---------------------------------------------------------------------------

    \31\ Based on the RfD in IRIS (2E-1 mg/kg-day) and a 90th 
percentile drinking water intake rate in children (64 mL/Kg/day).
---------------------------------------------------------------------------

    (3) Organics from the Trona skimmer. We propose not to list the 
organics (chlorinated hydrocarbons) recovered from the Trona skimmer. 
The organics are stored in a covered tank before being shipped off-
site. For those scenarios where wastes are managed in a tank, the 
impervious nature of the construction materials (concrete, fiberglass, 
or steel) of tanks is unlikely to result in releases to groundwater in 
all but the most catastrophic scenarios. We also are not concerned with 
potential air releases because both the Trona skimmer and tank are 
covered. The waste is shipped off-site to a Subtitle C permitted 
blender prior to being burned for energy recovery in cement kilns. 
Burning by cement kilns is regulated under MACT standards for cement 
kilns (64 FR 31989, June 14, 1999 and 64 FR 52827, September 30, 1999). 
Therefore, we did not further evaluate potential risks from burning the 
organics under this listing. The facility reported a California-only 
hazardous waste code CA343 (organic liquids, unspecified) for the waste 
but did not report any federal characteristic codes. The facility 
manifests the waste using the California code when they send it to the 
blender. Because this waste has significant BTU value and also carries 
a state hazardous waste code, we expect this management practice to 
continue; we do not believe there would be any significant benefit to 
the environment by listing this waste.
    (4) Sludges from containment areas. We propose not to list the 
sludges collected from containment areas around the process tanks, the 
loading section, LLX strippers, Wemco flotation cells and API settlers. 
The facility reported a California-only hazardous waste code CA611 
(petroleum contaminated soils) for the waste but did not report any 
federal characteristic codes. The facility stores the waste on-site in 
drums, transfers to it to 20 cubic yard roll-off bins and mixes the 
sludge with soil, and then ships the waste off-site with a manifest as 
a California-only hazardous waste to a Subtitle C landfill. The 
facility is tied to its location in California so we believe it is 
plausible that the waste will always be treated as a California-only 
hazardous waste. We do not believe there would be any significant 
benefit to the environment by listing this waste.
    (5) Spent activated carbon. We propose not to list the carbon that 
is regenerated on-site. The carbon is regenerated in an on-site 
furnace. The carbon filtration process occurs later in the process 
after much of the organic additives have settled out of the borate 
liquor. Consequently, we expect that the filters will not collect high 
concentrations of constituents of concern, except perhaps kerosene 
related organics. We expect any such constituents that are filtered out 
using carbon adsorption to be combustible. There is no potential for 
exposure prior to the regeneration process or during the return of the 
activated carbon to the carbon filter. The furnace is permitted by the 
State of California Air Control Board. Although the permit does not 
contain any requirements for emission controls, it does require annual 
reporting. We reviewed the emissions data and do not believe that the 
emissions from the furnace are of concern. The reported emission levels 
are significantly below the MACT standards for permitted hazardous 
waste incinerators (64 FR 52827, September 30, 1999). We expect the use 
of this furnace to continue because it is expedient to regenerate the 
carbon on-site, and the facility is unlikely to relocate given the 
proximity of the mineralized brine source. Therefore, we propose not to 
list this waste.
    d. Agency evaluation of wastes generated by the kernite ore 
process.
What Kinds of Wastes Are Generated by the Kernite ore Process?
    The facility generates two primary wastestreams: Tailings and 
gangue. The tailings include the wastewaters and fine insolubles from 
ore processing and boric acid production. The tailings are managed in 
tanks and then pumped to on-site evaporation ponds/surface 
impoundments. The boric acid gangue which includes clay, sand and other

[[Page 55712]]

course insolubles, is produced during the separation of solids from the 
borate liquor, a step the facility calls ``classification.'' The gangue 
is placed on a slab for drainage and then managed in on-site waste 
piles with gangue produced from the other production process at the 
facility. The drainage from the slab is sent to the tailings ponds. The 
remaining wastestream is comprised of the filters from the filtration 
of the borate liquor to remove any remaining insoluble ore material 
prior to crystallization. The filter aid is washed off weekly and 
managed with the tailings. The spent filters are transferred to a solid 
waste bin in preparation for on-site disposal in a industrial Subtitle 
D landfill.
    In addition to the above wastes, the facility also produces off-
specification product that is put directly back to the production 
process. Because the material is reused on-site in production units in 
ways that present low potential for release, and because we evaluated 
process waste generated after the secondary material is reinserted into 
the process, we do not believe that the off-specification product 
presents significant risks. Note that, when facilities process off-
specification product by reinserting the off-specification product back 
into the process where it originated, without reclamation, the off-
specification product would not be a solid waste.
    The facility made beneficiation exemption claims under the Bevill 
amendments for the tailings and gangue wastes. Because we propose not 
to list these wastes, we did not review the facility's Bevill exemption 
claims.
How Are the Wastes From the Kernite Ore Process Currently Managed?
    Table III-7 summarizes our information about these wastes:

           Table III-7.--Boric Acid: Kernite Ore Process Wastes
------------------------------------------------------------------------
                                                          Sequential
        Waste category             1998 volume      management practices
------------------------------------------------------------------------
 Tailings...................  Up to 750,000         (1) Stored in tank;
                               gallons/day1.        (2) Pumped to
                                                     evaporation ponds/
                                                     surface
                                                     impoundments.
 Gangue.....................  Portion of 900,000    (1) Placed on slab
                               MT2.                  for drainage;
                                                    (2) Trucked to on-
                                                     site waste piles.
Spent filters...............  3...................  (1) Stored in solid
                                                     waste bin;
                                                    (2) On-site
                                                     industrial Subtitle
                                                     D landfill.
------------------------------------------------------------------------
 1 Capacity volume for boric acid surface impoundments. Current daily
  quantity is lower. Source: California Regional Water Quality Control
  Board permit, board order 6-93-17.
 2 The boric acid coarse gangue is co-mingled with gangue from the other
  production process at the facility. That process is outside the scope
  of the consent decree. The boric acid gangue represents only a minor
  proportion of the total 900,000 tons of gangue typically deposited
  annually on the waste piles. Source: California Regional Water Quality
  Control Board permit, board order 6-93-17.

What Is EPA's Decision About Whether To List These Wastes as Hazardous?
    For the reasons set out below, we propose not to list any wastes 
from the kernite ore process for the production of boric acid.
    (1) Tailings. We propose not to list the tailings from boric acid 
production. The tailings are managed in a tank and then pumped to 
evaporation ponds. The facility provided TCLP data for the tailings. 
Those data show waste contains arsenic and antimony above health-based 
drinking water levels. The Agency also assumed that boron was present 
in significant levels due to the nature of the ore. The facility 
provided total levels for the boron concentration in the waste. We 
conducted an in-depth review of the groundwater conditions at the site 
and have concluded that a groundwater exposure pathway does not exist. 
No one is currently living near the facility boundary closest to the 
waste management unit areas and it is unlikely that future development 
will occur. The closest existing drinking water well is two miles away 
from the waste management units. It is a community well and is subject 
to all applicable drinking water standards. In addition, there are 
several factors described below which make contamination of this well 
from a potential release from the facility's evaporation ponds 
unlikely.
    The groundwater under the off-site area of land closest to the 
waste management units is not suitable for use as drinking water. The 
ore body, which is the raw material for the process, has a localized 
impact on the groundwater in its vicinity. Monitoring wells in the area 
show that the groundwater in the geologic strata underneath the off-
site area adjacent to the waste management units has total dissolved 
solids (TDS) levels in excess of three times the maximum level for an 
aquifer to be considered a drinking water source in California.\32\ 
Additional factors such as low flow rate and high treatment cost make 
the potential for a private well in that area highly unlikely. 
Municipalities can tap into an alternative water source through a 
regional pipeline and need not rely on groundwater.
---------------------------------------------------------------------------

    \32\ California Water Quality Control Plan for the Lathontan 
Regions, revised 1991 (p. 4.6-1)
---------------------------------------------------------------------------

    The geology of the area has several characteristics that reduce the 
potential for releases from the impoundments from reaching known 
drinking water sources. The transport time to groundwater for the 
constituents of concern appears to be significant given the depth to 
groundwater under the waste management units (170-220 feet) and the 
affinity of these constituents to bind with soil.\33\ The area under 
the facility has several geologic faults that act as groundwater 
barriers. The South Borax fault is likely to prevent any potential 
release from the waste management units from reaching the drinking 
water source for the existing community well. The fault is located just 
south of the waste management units, between the units and the well. In 
addition, the groundwater underlying the waste management units is 
contained in the tertiary soil layer whereas the community well draws 
from the quaternary layer. We believe that migration between these two 
layers would be limited. (The facility submitted a detailed summary of 
the geologic conditions at the site. This information has been placed 
in the docket for this rulemaking. See ``Summary of Boron Operations 
Hydrogeology, Potential Groundwater Receptors and BAP Waste Management 
Parameters''). Finally, we note that the impoundments in question are 
designed with a triple liner and leachate collection system, making any 
significant release less likely over the active life of the units. 
Based on these factors, we do not believe there is a

[[Page 55713]]

groundwater exposure pathway from the tailings.
---------------------------------------------------------------------------

    \33\ Source: California Regional Water Quality Control Board 
permit, board order 6-93-17.
---------------------------------------------------------------------------

    We also assessed the potential for air releases from the tailings 
ponds. Because the constituents of concern from this process are 
nonvolatile metals, we are not concerned with releases through 
volatilization. Although the surface impoundments are evaporation 
ponds, the facility claims that there is still some level of moisture 
in the ponds at all times, thereby minimizing release of particulates 
to the air. The particulates would not likely be subject to wind blown 
erosion due to the moisture level of the waste. Furthermore, the 
closest off-site receptors are at least two miles away from the unit. 
Due to dispersion, it is unlikely that any particulate releases would 
reach such receptors at significant levels. The facility also provided 
a risk assessment which assessed the air risks from the tailings ponds. 
Their assessment did not show any air risks from the tailings ponds 
even when they assumed a conservative dry down process for the unit. 
(The facility's air risk assessment is available in the RCRA docket for 
today's proposal).
    In summary, there are several site specific factors that need to be 
taken into account when evaluating risks from this waste. This is the 
only facility in the country producing boric acid from ore. The 
facility is tied to its location because it is the source of the ore. 
The hydrogeology of the site is such that local groundwater is not 
suitable for drinking water use, and any potential releases from the 
unit would be unlikely to migrate to any drinking water source. 
Furthermore, the facility is remote with the nearest receptors two 
miles away. Based on all of these facts, we propose not to list the 
tailings from the kernite ore process for the production of boric acid.
    (2) Gangue. We propose not to list the gangue generated during the 
boric acid process. Initially, the gangue is placed on a slab to drain. 
The drainage from the gangue is collected and managed with the tailings 
(we assessed the drainage as part of the tailings wastestream; see 
section (1) above for our listing recommendation). The drained gangue 
is trucked to on-site waste piles. The gangue is wet when transported 
to the waste pile but most of the moisture evaporates quickly in the 
dry desert environment. The same geological conditions apply to the 
gangue waste unit as described above for the tailings waste unit. The 
gangue is ultimately managed as a dry waste pile and there is virtually 
no precipitation to cause leaching. We assumed a greater risk to 
groundwater would come from the tailings because there is any liquid 
associated with the gangue would evaporate before leaching into the 
subsurface. Based on our decision regarding the tailings, we did not 
further evaluate the risks to groundwater from the gangue.
    We did assess in more detail the potential for air releases from 
the waste pile. We do not expect releases of the nonvolatile metals 
from this waste. The moist gangue solids are trucked to on-site waste 
piles. The gangue contains enough sodium sulfate to cause the gangue 
piles to set up like cement when it dries, helping prevent erosion and 
air release of particulates from the pile. As a further check of 
potential air releases, we examined the potential for release of the 
constituent of most concern, arsenic. According to data provided by the 
facility, the total levels of arsenic in the gangue vary between 25 and 
78 mg/kg. We compared these total concentrations to one of the levels 
calculated as part of the EPA's Air Characteristic Study (530-R-99-
019b, Aug 1999, Table 4-3). The Study evaluated different waste 
management and receptor scenarios to determine waste concentrations 
that would remain below a specific target risk. Using the waste pile 
scenario at a receptor distance of 150 meters, the study showed that 
arsenic levels of 6,000 ppm did not cause exceedences of the target 
risk levels. The concentration levels in the gangue are well below this 
number. In addition, the location of the facility is remote with the 
closest residence two miles away, which is significantly beyond the 150 
meter range. The Air Characteristics Study only evaluated direct risks 
from inhalation, not indirect risks. However, due to the desert 
environment where the facility is located, risks related to consumption 
of soil, plants or animals are highly unlikely to arise. Based on these 
factors, we believe that the arsenic levels in the gangue do not 
present unacceptable risks via the air pathway.
    In addition to arsenic, boron and antimony are the two other 
constituents of concern present in the gangue. Based on data provided 
by the facility, antimony is found at total concentrations ranging from 
36 mg/kg to 84 mg/kg in the gangue. The facility estimated the boron 
total concentration levels to be 25,000 ppm based on average daily 
sampling of the gangue. Arsenic is the most toxic of the three 
constituents. Because the particulate releases and exposure scenario 
would likely be the same for all three constituents and because, as 
discussed above, we do not believe arsenic poses a concern, we also 
believe there are no unacceptable levels of risk from the antimony and 
boron in the gangue. After assessing possible risks from arsenic, we 
compared the ratios of the waste concentrations for the three 
constituents to the ingestion health-based level for each constituent. 
This ratio for arsenic was an order of magnitude higher than the ratios 
for antimony and boron, indicating that the highest potential risk from 
ingestion would arise from the arsenic. Thus, based on the lack of 
significant risk for arsenic in this waste, the Agency concluded that 
neither antimony nor boron pose a significant air risk at this site. In 
addition, as mentioned above in the tailings section, the facility has 
conducted an air risk assessment. The document shows no significant 
risk from the management practices for the gangue waste pile. The 
facility's risk assessment is available in the docket for today's 
proposal. Therefore, based on all of these factors, we propose not to 
list the gangue from the production of boric acid using the kernite ore 
process.
    (3) Spent filters. We propose not to list the spent filters 
generated during the filtration step of the boric acid production 
process. The spent filters are stored in a solid waste bin and then 
managed in an on-site industrial Subtitle D landfill. The filtration 
step occurs late in the process, so we expect minimal contamination. In 
addition, because the filters are washed weekly, the vast majority of 
any contaminants filtered out at this stage would be captured by the 
wash process and managed with the tailings (see section (1) above for 
listing determination on the tailings). The facility applies a daily 
cover at the landfill which protects against residual particulates from 
being released into the air. Furthermore, the quantity of spent filters 
is relatively small (3 MT), making it unlikely to present a significant 
risk in the landfill. Finally, the location of the facility is remote 
with the closest residence being two miles away. Therefore, we propose 
not to list the spent filters from the kernite ore process for the 
production of boric acid.
4. Cadmium Pigments
    a. Summary. We propose not to list any wastes from the production 
of cadmium pigments. All of the non-wastewater residuals consistently 
exhibit the toxicity characteristic for barium, cadmium, and selenium. 
There is only one producer, and over the past seven years the producer 
has drummed and shipped with manifests all its non-wastewater residuals 
to an off-site Subtitle C facility for treatment to applicable LDR 
standards. The

[[Page 55714]]

wastewaters are pretreated on-site in closed tanks prior to discharge 
to a POTW, which is regulated under the Clean Water Act. We conclude 
that the existing regulatory controls adequately reduce risks, and 
there are no exposure pathways of concern. These wastes do not pose a 
substantial present or potential hazard, and thus do not meet the 
criteria for listing set out in 40 CFR 261.11(a)(3).
    b. Description of the cadmium pigments industry. One facility 
produced cadmium pigments in the United States in 1998 and 1999. 
Cadmium pigments are cadmium sulfides of variable composition, usually 
produced as powders but also available in other forms such as pastes 
and liquids. Cadmium pigments are used to provide shades of bright 
yellow, orange, red, and maroon. The shades depend on the ratio of 
cadmium and zinc to sulfides and selenium. Current uses of cadmium 
pigments include decorative and protective coatings for plastics, 
glass, ceramics, rubber and other materials. The coatings provide heat 
resistance to surfaces and a barrier to chemical and sunlight 
exposures.
    Cadmium pigments are produced by digesting cadmium metal in 
sulfuric acid, nitric acid, and water to produce a cadmium sulfate 
solution (liquor). Chemical reagents are added to the liquor to 
selectively precipitate out metals which are present as impurities. 
Sodium sulfide and metals (e.g., zinc, selenium) are added to the 
purified liquor to yield a slurry which, after filtration, is the 
``greencake'', the first intermediate product from the cadmium pigments 
production. The greencakes are then washed, sized, and calcined. The 
calcined materials are ground, rewashed, filtered, dried, milled, and 
blended to make different shades.
    The use of cadmium pigments is declining.\34\ Growth in the overall 
demand for cadmium pigments is limited to the manufacturing areas 
requiring use of cadmium pigments, such as the plastics industry, where 
no substitute is adequate. Our RCRA Section 3007 Survey results show 
that six out of seven facilities ceased production of cadmium pigments 
in recent years. The domestic demand for cadmium pigments in the next 
few years is likely to remain stable. A more complete discussion of 
this process and the industry is provided in the ``Cadmium Pigments 
Listing Background Document for the Inorganic Chemical Listing 
Determination'' in the docket for today's proposal.
---------------------------------------------------------------------------

    \34\ USGS Minerals Information, Mineral Commodity Summary, 1996 
(see http://minerals.usgs.gov/minerals/pubs/commodity/cadmium/140396.txt)
---------------------------------------------------------------------------

    b. What kinds of wastes are generated by this process?. Using the 
facility's survey response, we divided the wastes into two broad 
categories: Wastewaters and non-wastewaters. Table III-8 summarizes the 
types of wastes in each category, the characteristics of each waste, 
waste volume, and current management practices:

                                 Table III-8.--Cadmium Pigment Production Wastes
----------------------------------------------------------------------------------------------------------------
                                       Reported  waste
           Waste category                   codes          1998 waste  volume  (MT)       Management practice
----------------------------------------------------------------------------------------------------------------
                                                 Non-wastewaters
----------------------------------------------------------------------------------------------------------------
Miscellaneous solid wastes,          D005                 33.5......................  Each waste is drummed
 including materials from dust       D006                                              (separately or sometimes
 collectors, plant cleanup,          D010                                              combined) and shipped to
 filtered pigments from the                                                            a commercial off-site
 presses, and from the on-site                                                         hazardous waste treatment
 wastewater pre-treatment process.                                                     facility to be treated
                                                                                       and decharacterized
                                                                                       before placing in a
                                                                                       Subtitle D landfill.
                                                                                      Note:
                                                                                      D005--barium
                                                                                      D006--cadmium
                                                                                      D010--selenium
Contaminated paper and cloth,        D005                 9.3
 including filter bags, filter       D006
 cloths, filter cartridges, and      D010
 dust collector bags.
Contaminated gaskets generated from  D005                 0.3
 the red and yellow calciners.       D006
                                     D010
Iron press residue generated from    D005                 4.5                         ..........................
 digestion of cadmium metal.         D006
                                     D010
----------------------------------------------------------------------------------------------------------------
                                                   Wastewaters
----------------------------------------------------------------------------------------------------------------


 
 
----------------------------------------------------------------------------------------------------------------
Gas scrubber wastewater (spent   ................  Not reported...........  pH adjusted,       All these
 caustic from scrubbing vapors                                               treated to         wastewaters are
 generated from calcination                                                  remove zinc and    then combined
 process).                                                                   cadmium. The       and further
                                                                             resulting sludge   treated in on-
                                                                             is a part of the   site closed
                                                                             miscellaneous      tanks for pH
                                                                             solid wastes.      adjustment; 2-
                                                                                                step filtration;
                                                                                                monitoring for
                                                                                                turbidity prior
                                                                                                to discharge to
                                                                                                a POTW.
Process wastewater from          ................  Not reported...........  pH adjusted,
 filtering the greencake.                                                    treated to
                                                                             recover cadmium.
Process wastewaters from wet     ................  Not reported...........
 washing system.
----------------------------------------------------------------------------------------------------------------


[[Page 55715]]

    c. Agency evaluation. After evaluating the characteristics and 
current management practices of all the waste residuals, we determined 
that: (1) all the non-wastewater wastes are being properly treated and 
managed as hazardous wastes under RCRA regulations, and (2) all the 
wastewaters are being treated on-site in closed tanks and discharged to 
a permitted POTW, where they are subject to the Clean Water Act. 
Therefore, we did not pursue risk assessment modeling for any of these 
wastes. The following are the details of our evaluation:
    (1) Non-wastewaters. In its RCRA Section 3007 Survey, the facility 
classified all four wastes of this category as characteristic 
hazardous, as generated, for barium, cadmium, and selenium. The 
facility also provided data characterizing each non-wastewater residual 
for total and TCLP concentrations of eight TC metals. Except for 
chromium (which was detected in the TCLP leachate of one waste below 
its health-based level), no other hazardous constituents were reported. 
The total volume of these four wastes was 47.6 metric tons in 1998.
    Over the past seven years the generator has managed all its non-
wastewater wastes generated from the production of cadmium pigments as 
TC hazardous wastes. These wastes are drummed and shipped with 
manifests to a commercial off-site Subtitle C facility for treatment. 
The off-site treatment includes mixing and treating the wastes with 
other solid wastes and the addition of lime and fly ash to meet the 
current LDR treatment standards (via stabilization). The resultant 
mixture forms a concrete-like residue, which no longer exhibits a 
characteristic and is managed in a Subtitle D landfill. We believe this 
management, which complies with existing Subtitle C regulations, 
adequately protects human health and the environment.
    Although we generally believe that Subtitle C regulations for 
characteristic wastes adequately prevent mismanagement, we have 
additional data that help confirm our conclusion for this waste. The 
landfill information and leachate data provided by the local and state 
governments (per our request) indicate that the landfill has a liner 
with a leachate collection system. The landfill leachate data \35\ we 
have to date demonstrate that constituents detected in the landfill 
leachates are not attributable to the cadmium pigments production 
wastes. The landfill information and leachate data are provided in the 
``Cadmium Pigments Listing Background Document for the Inorganic 
Chemical Listing Determination'' in the docket for today's proposal. We 
recognize that the residues from commercial treatment facilities 
represent the commingling of wastes from a variety of facilities and 
wastes. Therefore, information on the landfill leachate from treated 
material is of limited use. However, the data available indicate that 
the cadmium pigment wastes do not present a substantial hazard when 
disposed. Given that the generating facility has followed the reported 
management practice for seven years, we believe use of this or 
comparable treatment and disposal will continue.
---------------------------------------------------------------------------

    \35\ Quarterly leachate monitoring data from March 95 to 
September 98, provided by Michigan's Department of Environment, 
Wayne County District Office and Local Office.
---------------------------------------------------------------------------

What Is EPA's Listing Rationale for These Wastes?
    We propose not to list any of the four wastes in this category as 
hazardous because they are already managed in compliance with existing 
hazardous waste regulations, including full compliance with the BDAT 
requirements for treatment prior to land disposal. We conclude that 
available data on the specific cadmium pigment manufacturing wastes do 
not support a decision to list the wastes as hazardous.
    (2) Wastewaters. We propose not to list the wastewaters as 
hazardous because the gas scrubber and the process wastewaters are 
pretreated on-site in closed tanks prior to discharge to a POTW. The 
wastewater treatment tanks provide sufficient structural integrity to 
minimize potential releases to groundwater. We are unlikely to find 
potential air releases from these tanks as neither volatile 
contaminants nor airborne particulates are likely to be present in 
these wastewaters. During treatment, the closed tanks present no 
significant threat of release to the environment. After treatment, the 
wastewaters are subject to the Clean Water Act program. We conclude 
that the wastewaters do not warrant listing. We assessed solids from 
the on-site treatment as miscellaneous wastes discussed above in 
section (1).
5. Inorganic Hydrogen Cyanide
    a. Summary. We propose not to list any wastes from the production 
of inorganic hydrogen cyanide (HCN) as hazardous under Subtitle C of 
RCRA. These wastes are managed in on-site wastewater treatment 
processes, industrial landfills, municipal landfills, hazardous waste 
incinerators, hazardous waste landfills, and hazardous waste injection 
wells. After analysis of these waste management practices and potential 
exposure pathways, we concluded that there are no risk pathways of 
concern. These wastes do not meet the criteria set out at 40 CFR 
261.11(a)(3) for listing as hazardous. They do not pose a substantial 
present or potential hazard to human health or the environment.
    b. Description of the inorganic hydrogen cyanide industry. Hydrogen 
cyanide (HCN) is used in the manufacture of a number of important 
chemicals including: adiponitrile to produce nylon, methyl methacrylate 
to produce clear acrylic plastics, sodium cyanide for the recovery of 
gold, triazines for agricultural herbicides, methionine for animal food 
supplements, and chelating agents for water treatment.
    HCN is manufactured via two primary inorganic synthesis processes: 
Andrussow and Blausaure-Methan-Ammoniak (BMA). The Andrussow process 
involves the reaction of ammonia, methane (natural gas) and air over a 
platinum catalyst; the BMA process is similar except the reaction 
occurs in the absence of air. The reaction products are quenched with 
water. Excess ammonia reactant is recovered for reuse in the reaction 
or converted to an ammonium salt. The aqueous HCN product is purified 
and concentrated for use as a liquid feedstock for manufacturing of one 
or more of the final products mentioned above. Two of the Andrussow 
process manufacturers do not produce a liquid hydrogen cyanide 
intermediate product but immediately convert the hydrogen cyanide in 
the reactor gases in a sodium hydroxide contactor to produce liquid 
sodium cyanide.
    There are ten manufacturers of hydrogen cyanide in the United 
States who use the Andrussow or the BMA process. Of these ten 
manufacturers, only one uses the BMA process. Two of the nine Andrussow 
manufacturers use an abbreviated version of the Andrussow process to 
produce sodium cyanide. Manufacture of sodium cyanide as a final 
product results in fewer wastes and significantly lower wastewater 
volumes.
    The inorganic hydrogen cyanide industry subject to this rulemaking 
is composed only of the facilities that produce hydrogen cyanide as an 
intermediate product or feedstock to manufacture a variety of 
commercial chemicals using the Andrussow and BMA processes. This 
proposal specifically does not cover wastes from the manufacturing of 
HCN as a byproduct in the manufacture of acrylonitrile by the 
ammoxidation of

[[Page 55716]]

propylene (Sohio process). The Sohio process is inherently an organic 
chemical manufacturing process, and is not within the scope of the 
inorganic chemicals manufacturing industry or the consent decree. 
Furthermore, we have already evaluated wastes for acrylonitrile 
manufacturing, and the cyanide wastes associated with the Sohio process 
(K011, K013, and K014) are subject to Subtitle C regulation.
    c. What kinds of wastes are generated by this process?
How Did We Categorize the Wastes?
    Wastes generated from the production of hydrogen cyanide consist of 
various types of wastewater, various types of spent filter media, spent 
catalyst, biological solids from wastewater treatment, and ammonium 
salts. Based on an assessment of the wastes reported in the survey, the 
wastes were categorized as follows:

--Commingled wastewaters. This waste includes continuously generated 
wastewaters such as HCN purification wastewater and ammonia 
purification wastewater.
--Ammonia recycle cartridge and spent carbon filters. This waste 
consists of spent filter material and filter solids that are generated 
during the filtration of the recycled unreacted ammonia stream prior to 
being reused as process feedstock.
--Biological wastewater treatment solids. The biosolids are generated 
from the biological treatment of process and non-process wastewaters to 
remove residual cyanide and organonitrile contaminants.
--Feed gas cartridge and spent carbon filters. This waste consists of 
spent filter material and filter solids that are generated during the 
filtration of natural gas prior to being used as process feedstock.
--Process air cartridge filters. This waste consists of spent filter 
material and filter solids that are generated during the filtration of 
ambient air that is used in the reaction.
--Acid spray cartridge filters. The waste consists of spent filter 
cartridges and filter solids from acid spray filters used in the 
hydrogen cyanide stripper.
--Spent catalyst. This waste consists of metal gauze panels that 
contain the precious-metal catalyst used to catalyze the synthesis 
reaction. The catalyst activity diminishes with time and needs to be 
replaced with fresh catalyst periodically.
--Ammonium sulfate and ammonium phosphate. The ammonium wastes are 
generated from the neutralization of excess ammonia in the process 
using sulfuric or phosphoric acid.
--Miscellaneous wastewaters. These numerous wastewaters are generated 
during plant upsets or shutdowns for maintenance and are reported in 
detail in the ``Inorganic Hydrogen Cyanide Listing Background Document 
for the Inorganic Chemical Listing Determination.''
--HCN polymer and sump wastes. These wastes are generated in process 
vessels, tanks, and wastewater collection sumps and removed during 
periodic plant maintenance operations.
--Sludge from wastewater collection tank. This waste is generated from 
the settling of suspended solids in wastewater tanks and removed during 
periodic plant maintenance operations.
--HCN storage tank solids. These solids settle out of the HCN product. 
The solids are generated during manual tank cleaning after thorough 
washing.
--Wastewater filters. These are generated from the filtration of 
process wastewater prior to deep-well injection.
--Ammonium sulfate filters. This waste is from the filtration of the 
ammonium sulfate solution from the neutralization of excess ammonia by 
sulfuric acid. The filtered ammonium sulfate solution is then 
crystallized into solid form prior to sale as fertilizer.
--Spent ammonium phosphate. Ammonium phosphate solution is used to 
scrub the off-gas from the reactor to assist in ammonium recovery.
--Organic layer from wastewater collection tank. This is generated from 
the treatment of commingled HCN wastewater and predominantly non-HCN 
process wastewater.

    In addition to these wastes, other residuals are produced by some 
of the facilities that are recycled back to the production process. 
These materials consist of process water and recovered ammonia. These 
residuals are reused on-site via enclosed piping systems and tanks, 
minimizing the potential for environmental releases. Also, we evaluated 
all wastes generated after these secondary materials are reinserted or 
reused; we do not believe that these secondary materials present 
significant risks. Consequently, we did not evaluate them further.
How Are These Wastes Currently Being Managed?
    Table III-9 summarizes the major waste categories, waste 
characteristics, waste volumes, and their current management practices:

       Table III-9.--Inorganic Hydrogen Cyanide Production Wastes
------------------------------------------------------------------------
                                                1998
 Waste Category  (Number of      Reported      volume       Management
         facilities)          Waste Codes 1     (MT)        practices
------------------------------------------------------------------------
Commingled wastewaters (8)..  D002.........   5,600,000  On-site
                                                          wastewater
                                                          treatment in
                                                          tanks or
                                                          surface
                                                          impoundments,
                                                          discharge to
                                                          NPDES outfall
                                                          or POTW.
Ammonia recycle cartridge     none.........          73  Off-site
 and spent carbon filters                                 municipal D
 (5).                                                     landfill; off-
                                                          site
                                                          industrial D
                                                          landfill; on-
                                                          site Subtitle
                                                          C landfill; on-
                                                          site Subtitle
                                                          C
                                                          incineration.
Biological wastewater         none; F0393..      45,397  Off-site
 treatment solids (4).                                    industrial
                                                          Subtitle D
                                                          landfill; off-
                                                          site municipal
                                                          Subtitle D
                                                          landfill; on-
                                                          site Subtitle
                                                          C landfill.
Feed gas cartridge and spent  none.........         9.7  Off-site
 carbon filters (9).                                      municipal D
                                                          landfill; off-
                                                          site
                                                          industrial D
                                                          landfill; on-
                                                          site Subtitle
                                                          C landfill as
                                                          non-hazardous
                                                          waste; off-
                                                          site recycle/
                                                          reuse via
                                                          return to
                                                          manufacturer.
Process air cartridge         none.........         7.5  Off-site
 filters (8).                                             municipal D
                                                          landfill; off-
                                                          site
                                                          industrial D
                                                          landfill;
                                                          reclamation.

[[Page 55717]]

 
Acid spray cartridge filters  none.........         1.1  On-site
 (1).                                                     Subtitle C
                                                          landfill as
                                                          nonhazardous
                                                          waste.
Spent catalyst (10).........  none.........        4.06  Off-site
                                                          reclamation.
Ammonium sulfate and          none.........      27,425  Off-site use as
 ammonium phosphate (3).                                  fertilizer.
Miscellaneous wastewaters     none.........     209,000  Managed with
 (4).                                                     commingled
                                                          wastewaters
                                                          described
                                                          above.
HCN polymer and sump wastes   none.........         0.7  Off-site
 (1).                                                     industrial D
                                                          landfill
Sludge from wastewater        D001;D018....        23.9  Stabilization/
 collection tank (2).                                     off-site
                                                          Subtitle C
                                                          landfill; off-
                                                          site Subtitle
                                                          C
                                                          incineration.
HCN storage tank solids (1).  none.........         0.3  Off-site
                                                          municipal D
                                                          landfill
Wastewater filters (1)......  none.........         450  Captive off-
                                                          site Subtitle
                                                          C
                                                          incineration.
Ammonium sulfate filters (1)  none.........         1.1  Off-site
                                                          industrial D
                                                          landfill
Spent Ammonium Phosphate (1)  none.........         230  On-site reuse
                                                          as biological
                                                          treatment
                                                          system
                                                          nutrient
                                                          source or on-
                                                          site
                                                          nonhazardous
                                                          waste
                                                          incineration
Organic layer from            D001.........        43.3  Off-site
 wastewater collection tank                      (1993)   Subtitle C
 (1).                                                     incineration
------------------------------------------------------------------------
1 D001 (ignitability), D002 (corrosivity), D018 (benzene).
2 Includes 2.1 MT reported for 1993.
3 One facility commingles wastewater to generate a hazardous waste
  derived from F039 wastewater.

    d. Agency evaluation. We selected three facilities in Alabama, 
Tennessee, and Texas to collect record samples of wastes for the 
listing determination. These facilities were selected based on the 
survey information for the entire industry sector and collectively 
represent all the wastes generated and all of the waste management 
practices used by the manufacturing sector.
    (1) Commingled wastewaters.
How Many Facilities Generate This Waste Category and How Is It Managed?
    Eight of the ten facilities generated commingled wastewaters from 
the inorganic hydrogen cyanide process. The total volume of commingled 
wastewaters reported by these facilities was 5.5 million MT in 1998. 
Six of these eight facilities treat the commingled wastewaters using 
one or more of the following operations in their on-site wastewater 
treatment processes: (a) steam stripping to remove cyanide and ammonia, 
with off-gasses vented to flares, scrubbers or incinerators; (b) pH 
adjustment; (c) aerated or non-aerated biological treatment in tanks or 
lined/unlined surface impoundments; (d) ozone treatment in tanks; (e) 
oxychlorination in surface impoundments; (f) settling in surface 
impoundments; and NPDES outfalls, or POTWs. In addition to commingling 
of the hydrogen cyanide process wastewaters, some facilities also 
commingle these wastewaters with wastewaters from other non-HCN 
processes generated in the same chemical manufacturing complex. The 
remaining two facilities manage their commingled wastewaters by 
filtration and disposal via deepwell injection.
What Management Scenarios Were Assessed?
    Based on the reported management practices, we assessed the 
potential for releases from tanks and surface impoundments. We decided 
that risks from the ultimate discharges to NPDES outfalls and POTWs are 
adequately controlled by the Clean Water Act. Risks from discharges to 
Class I injection wells with RCRA ``no-migration'' variances are 
adequately regulated under the Safe Drinking Water Act and RCRA (see 
section III.D.3).
    Potential releases to groundwater. We assessed both the tank and 
surface impoundment scenarios for potential releases to groundwater and 
determined that the unlined surface impoundment scenario poses a more 
significant potential risk to groundwater than the tank scenario. We 
focused on the surface impoundment pathway because several of the 
reported surface impoundments are unlined, posing a potential direct 
release pathway to groundwater. We take the position that tanks, by the 
impervious nature of the construction materials (concrete, fiberglass, 
or steel) are not likely to result in significant releases to 
groundwater. We conducted sampling and analysis of these wastewaters at 
the three facilities located in Alabama, Tennessee, and Texas currently 
using surface impoundment-based wastewater treatment systems. We 
assessed each site individually, because we believe it is reasonable to 
assume that large volume wastewaters managed in impoundments in 
question would not be moved off-site or to different locations.
    Our decision on what scenario to assess was based on review of our 
analytical data and the characteristics of the surface impoundments 
used at the three facilities. We evaluated the potential for 
groundwater releases to drinking water wells at the Alabama site, and 
potential surface water impacts at the Tennessee facility. The 
analytical data for the wastewater managed in the surface impoundment 
at the Texas facility showed that all levels of the toxicants of 
concern are below health-based levels, or are associated with other 
commingled on-site production processes and are not due to HCN 
production.
    The Alabama facility manages wastewater in a series of surface 
impoundments and tanks that provide equalization, oxidation, 
maturation, rock-reed filtration, and mixing. In addition, the facility 
has an emergency holding basin which has also been used for HCN process 
wastewaters. The surface impoundments are equipped with double 
synthetic liners with leachate detection and collection systems. The 
oxidation basin is a concrete-lined structure with an additional 
synthetic liner. Our analytical data indicates that concentrations at 
the inlet to the impoundments would exceed the HBLs for one constituent 
of concern (acetonitrile). A study of existing wells near the facility 
indicates the presence of private water wells within a one-mile radius 
of the property boundary. We

[[Page 55718]]

therefore assessed these units further for potential releases to 
groundwater.
    The Tennessee facility manages the wastewater in unlined surface 
impoundments and some of the toxicants of concern were above the 
health-based levels and water quality criteria, thus, we assessed this 
facility's impoundments for potential releases to groundwater. As 
described below, the Tennessee facility and its surface impoundments 
are sited on the banks of the Loosahatchie River, with no off-site 
downgradient wells. However, we did assess the impact from potential 
releases to groundwater to the nearby river at this site.
    Potential releases to air. We also examined the air exposure 
pathway for the wastewater treatment impoundments and tanks because of 
the potential release of volatile organic compounds and hydrogen 
cyanide from the wastewater treatment units. EPA is developing maximum 
achievable control technology (MACT) standards for cyanide 
manufacturing under the Clean Air Act (CAA), which may address these 
emissions. Although this rule will be technology-based, the CAA 
ultimately requires EPA to regulate significant risks remaining after 
the imposition of technology-based controls. EPA has also proposed 
regulations under the CAA for volatile organic compound (VOC) emissions 
from wastewater at Synthetic Organic Chemical Manufacturing Industry 
(SOCMI) facilities, which would cover the HCN manufacturers (see 
proposal at 60 FR 46780, September 12, 1994). Therefore, we are 
deferring control of any air releases to the MACT and SOCMI standards 
and did not assess this pathway further in today's proposal.
How Was This Waste Category Characterized?
    We conducted sampling and analysis of these wastewaters at the 
three facilities currently using surface impoundment-based wastewater 
treatment systems. We collected samples at various places in the 
process, including prior to commingling, so that we could assess the 
risks of the wastestream at issue here. Today's proposal is based 
primarily on samples of the commingled wastewaters collected in the 
wastewater treatment plants.\36\ For assessing the groundwater-to-
drinking water pathway at the Alabama facility, we used the sample 
collected at the HCN wastewater collection tank where the HCN 
wastewaters are collected prior to mixing with other non-HCN 
wastewaters in the equalization impoundment. We estimated the 
concentration of the constituents of concern in the equalization 
impoundment by applying the dilution factor in the impoundment (e.g., 
36 to 1 total wastewaters to HCN wastewaters), and we assessed these 
concentrations in our modeling for this pathway. For the groundwater-
to-surface water pathway at the Tennessee facility, we used the sample 
collected at the exit from the surface impoundments. We used the sample 
from wastewater exiting the unit, rather than at the inlet, because 
treatment occurs in the impoundment. However, the inlet data are 
similar, and even using the inlet data would not significantly increase 
the surface water screening results.
---------------------------------------------------------------------------

    \36\ The ``Inorganic Hydrogen Cyanide Listing Background 
Document for the Inorganic Chemical Listing Determination,'' 
available in the docket for today's proposal, provides all 
analytical data we developed, as well as split samples collected by 
industry, where available.
---------------------------------------------------------------------------

    We analyzed the waste for both amenable and total cyanide, as well 
as a number of volatile organics and metals. We used the amenable 
cyanide results as our cyanide risk assessment inputs because we 
believe that amenable cyanide most closely represents the fraction of 
cyanide likely to be mobile in a groundwater scenario and the ``free 
cyanide'' assessed in our health-based level (HBL). However, this had 
no impact on our risk results, because our data show that amenable and 
total cyanide results for this waste are the same.
    We sampled the wastewater at the Alabama facility in August, 1999. 
The analytical data for the commingled HCN wastewaters (DG-1-HC-07) 
represent waste concentrations prior to commingling with other non-HCN 
wastewaters. Our results for a key chemical, acetonitrile, are 
qualified as ``estimated'' for this sample as a result of problems 
during sampling and analyses at this site as described further in Waste 
Characterization Report, Degussa-Huls; February 25, 2000, available in 
the docket for today's proposal. The facility's split samples were more 
problematic, because the analytical instruments were not calibrated for 
key constituents being analyzed; thus, the split sample results appear 
even more uncertain. Despite the estimated nature of the results for 
acetonitrile in this waste sample, the data clearly indicate that 
acetonitrile is likely to be present in the waste. Acetonitrile, also 
commonly referred to as methyl cyanide, is a likely by-product from the 
main reaction between methane and ammonia to form hydrogen cyanide. In 
addition, samples we collected at the Tennessee facility show that 
significant levels of acetonitrile are present in the wastewater, 
albeit at somewhat lower levels than we found at the Alabama site.
    We initially sampled at the Tennessee facility in August of 1999 
(sample DM-1-HC-08). We used the analytical results for this sample as 
input to the risk assessment (described further below). However, 
because our analytical results for amenable cyanide were qualified due 
to holding time exceedences, we sampled at this facility a second time 
in October of 1999 to better understand the potential impact of this 
waste on the environment (DM-2-HC-08). All of the analytical data for 
these samples are available in ``Inorganic Hydrogen Cyanide Listing 
Background Document for the Inorganic Chemicals Listing Determination'' 
in the docket for today's proposal. The second round of sampling showed 
lower levels of the key constituent of potential concern than found in 
the first round of sampling. Due to time constraints, we did not re-run 
the risk assessment model for this pathway to incorporate the second 
round of analytical data. However, this would result in somewhat lower 
risks, and thus would have had not impacted our proposed decision.
    The critical analytical results for the commingled wastewaters for 
the Tennessee and Alabama surface impoundments are presented below in 
Table III-10. These represent the constituents found to be present in 
the wastewaters at level exceeding the HBLs or AWQC. (Several other 
constituents were marginally above the AWQC and were not important in 
the surface water screening.)

[[Page 55719]]



                             Table III-10.--Characterization of Commingled Wastewaters From Inorganic HCN Production (mg/L)
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                              Sample  DM-2-HC-08
      Constituent of concern          Sample  DM-1-HC-08            2nd Rnd           Sample  DG-1-HC-07            1 HBL                   AWQC
--------------------------------------------------------------------------------------------------------------------------------------------------------
Amenable CN.......................  0.638                   0.01                    0.509                   0.3                    0.005
Nitrite as N......................  11.5                    no analysis             2.5                     2                      1
Vinyl chloride....................  0.029                   3 0.0066 L              0.001                   0.0009 (0.1)           0.002
Acetonitrile......................  4 50 K                  28 L                    190                     0.09 (0.045)           2 N/A
Acrylonitrile.....................  0.013                   0.001                   0.0005                  0.002 (0.03)           5.9E-05
--------------------------------------------------------------------------------------------------------------------------------------------------------
1 HBL in parenthesis based on inhalation pathway from residential use of water (e.g., showering).
2 N/A: Not Applicable.
3 L: Qualified result with a low bias for positive result.
4 K: Qualified result with a high bias for positive result.

How Was the Groundwater-To-Drinking Water Risk Assessment Established?
    The Alabama facility's surface impoundments are located in the 
center of an industrial park on the west side of Mobile Bay. The 
wastewater treatment impoundments are located near the eastern property 
boundary of the facility and approximately 4,000 feet south of the 
State of Alabama barge canal. We chose to assess surface water risks at 
the Tennessee facility, which is closer to a surface water body. 
However, given the use of groundwater in the area around the Alabama 
facility, we assessed the possible impact on drinking water wells. We 
selected the equalization basin as the unit for quantitative modeling. 
This is the first surface impoundment in the series and is likely to 
hold the highest level of constituents of concern. We elected not to 
assess the emergency holding pond, which is used primarily during high 
stormwater events. Due to the intermittent use of the holding pond, we 
expect the potential for significant groundwater releases to be greater 
for the equalization pond. In addition, the equalization pond is 
covered with a floating synthetic membrane, while the holding pond is 
not.\37\ Our modeling of the covered equalization pond did not assume 
any loss of the volatile constituents of concern, thus allowing more of 
the constituents to infiltrate to the groundwater rather than 
volatilize to the air.
---------------------------------------------------------------------------

    \37\ The facility reported that the cover on the equalization 
unit was installed to ensure compliance with expected new 
regulations to control volatile organic carbon emissions from 
wastewater sources for the Synthetic Organic Chemical Manufacturing 
Industry (SOCMI) (proposal, 59 FR 46780, September 9, 1994).
---------------------------------------------------------------------------

    Based on information available in a corrective action plan related 
to a product spill on-site (Risk-Based Corrective Action Plan for the 
Sodium Cyanide Production Unit at Degussa Corporation Alabama Facility, 
Theodore, Alabama; March 19, 1998), the most likely direction of 
groundwater flow is to the low-lying areas to the north-northeast of 
the surface impoundments. We found there are drinking water wells 
located due east of the equalization surface impoundment. Although the 
wells are located east of the surface impoundment instead of the 
estimated north-northeast groundwater flow direction, they are at 
somewhat lower ground elevation than the surface impoundment. Given the 
uncertainty in the direction of the groundwater flow, we assumed that 
contaminated groundwater from the surface impoundment could migrate to 
the east and reach these wells. Based on the available land use and 
groundwater use information for this area, we performed risk modeling 
for potential releases to drinking water wells located between 3,100 
and 5,280 feet east of the surface impoundment. The minimum distance of 
3,100 feet is based on the distance from the impoundment to the eastern 
boundary of the industrial area controlled by the facility. The maximum 
distance of 5,280 is the distance east from the impoundment to the 
closest known well. This drinking water well appears to be located just 
inside the eastern boundary of the state property, which lies to the 
east of the industrial park where the facility is located. We also 
assumed that a future well may be placed in the same State property 
directly east of the facility's undeveloped tract at approximately 
3,100 feet from the surface impoundment. The details of this assessment 
are presented in the ``Risk Assessment for the Listing Determinations 
for Inorganic Chemical Manufacturing Wastes'' in the docket for today's 
proposal. The results of the risk modeling for the only drinking water 
constituent of concern are presented in Table III-11 below.

 Table III-11.--Groundwater Risk Results for Commingled Wastewaters From
              the Production of Inorganic Hydrogen Cyanide
------------------------------------------------------------------------
                                                            Acetonitrile
                                                               hazard
                        Percentile                            quotient
                                                               (HQ) 1
------------------------------------------------------------------------
90th %....................................................           0.3
95th %....................................................          0.5
------------------------------------------------------------------------
1 Risk from inhalation scenario during showering included exposure
  factors for both adult and child in the analysis.

How Was The Groundwater-To-Surface Water Risk Assessment Established?
    The Tennessee facility and its surface impoundments are sited on 
the banks of the Loosahatchie River. The surface impoundments are 
located approximately 800 feet from the river. Based on information 
available in the Remedial Facility Investigation (RFI),\38\ the 
direction of the groundwater flow is documented to be south towards the 
Loosahatchie River. The possibility of a public water supply well or 
private well being located downgradient of the Tennessee surface 
impoundments is unlikely because the facility boundary extends to the 
river to the south. Hence, based on the geologic setting of the 
facility as detailed above, we believe it is highly unlikely that these 
impoundments could impact drinking water wells via migration of a 
contaminated groundwater plume. Based on these facts we did not assess 
the groundwater-to-drinking water well pathway further at this site. We 
did, however, conduct a screening analysis of potential releases of 
groundwater to surface water and subsequent exposure via ingestion 
because of the proximity of the unit to the river. We calculated the 
concentrations in the river that would result from discharge of 
contaminated

[[Page 55720]]

groundwater by estimating the infiltration rate for the unlined 
impoundment and diluting the resulting leachate volume into the river 
under various flow conditions. The results of this screening level 
analysis suggest that concentrations of the constituents of concern in 
the river would be well below the aquatic life AWQC and HBLs for 
drinking water. The details of the screening analysis are presented in 
``Risk Assessment for the Listing Determinations for Inorganic Chemical 
Manufacturing Wastes'' in the docket for today's proposal.
---------------------------------------------------------------------------

    \38\ U.S. EPA Phase II RFI Workplan, Potentiometric Surface 
Plan, March 3 & 4, 1999.
---------------------------------------------------------------------------

What Is EPA's Listing Rationale for This Waste?
    Our risk assessment results for the surface impoundment scenario, 
summarized above for drinking water in Table III-11, suggest that the 
only constituent of concern that required modeling (acetonitrile) does 
not pose a substantial present or potential hazard to human health and 
the environment. The HQ was below one at both the 90th and 95th 
percentile in the probabilistic risk distribution.
    The results of our risk analysis also show that hypothetical 
releases to the adjacent river would not result in exceedences of risk 
thresholds. Our analysis was conducted at a screening level and thus is 
based on a number of conservative assumptions that may overstate actual 
risk. We did not account for dilution of the potential plume in 
groundwater flowing under the surface impoundment that would result in 
yet lower river concentrations. We did not account for the likelihood 
that river water would be pretreated prior to use for drinking and 
showering. We did not account for volatilization, biodegradation, or 
hydrolysis of the cyanide and other constituents prior to exposure. 
Even if we used the surface impoundment influent concentrations, rather 
than the exit concentrations, as input to the analysis, this waste 
would not exceed risk thresholds in the adjacent river.
    For these reasons, we propose not to list this waste category as 
hazardous. For a more complete description of this analysis, see ``Risk 
Assessment for the Listing Determination for Inorganic Chemical 
Manufacturing Wastes'' in the docket for this proposal.
    (2) Ammonia recycle cartridge and spent carbon filters.
How Many Facilities Generate This Waste Category and How Is It Managed?
    Five facilities reported generating 73 MT/year of filter media and 
waste solids in 1998 from the removal of organonitrile polymers from 
the ammonia recycle stream. The management methods reported by the 
industry were off-site municipal Subtitle D landfill, off-site 
industrial Subtitle D landfill, on-site Subtitle C incineration, and 
on-site Subtitle C landfill.
What Management Scenarios Were Assessed?
    We conducted risk assessment modeling for off-site disposal in both 
a municipal and an industrial landfill, using only those two waste 
volumes reported to be managed in off-site Subtitle D landfills; 
volumes managed as hazardous wastes were not included in this array. No 
significant volatile constituents were detected in this waste (only 
non-volatile metals were detected; see following section), thus 
volatilization from landfills to the air was not a pathway of concern.
    We did not conduct risk assessment of the voluntary Subtitle C 
landfill and incineration practices because we assumed that listing 
would not significantly increase regulatory control for these wastes. 
Note that these on-site captive units have sufficient capacity and 
flexibility to accept these relatively small volume non-hazardous 
wastes.
How Was This Waste Category Characterized?
    Two samples were collected at different facilities. We sampled 
again at both facilities because of problems with the cyanide analyses 
for the first set of analyses and elevated detection limits for certain 
metals in the Tennessee sample. Due to the schedule constraints of this 
determination, we initiated the risk analyses using the first round of 
samples. The risk analysis and second round of sampling and analysis 
were conducted in parallel. HBLs are shown in Table III-12.

                                               Table III-12.--Characterization of Ammonia Recycle Filters
                                                                         [mg/L]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                       RH-1-HC-05 (1st data  RH-2-HC-05 (2nd data  DM-1-HC-04 (1st data    DM-02-HC-04 (2nd
                                                               set)                  set)                  set)                data set)
                      Parameter                       ----------------------------------------------------------------------------------------    HBL
                                                          TCLP       SPLP       TCLP       SPLP       TCLP       SPLP       TCLP       SPLP
--------------------------------------------------------------------------------------------------------------------------------------------------------
Antimony.............................................   1 0.55 J       0.59        0.5      0.237        0.5        0.5        0.8       0.08      0.006
Arsenic..............................................  2 0.045 L      0.039        0.5     0.0137        0.5       0.05        0.5     0.0112     0.0007
Nickel...............................................     0.50 J       0.61        0.2      0.303        0.2     0.0654        0.2     0.0178       0.31
    Total CN.........................................        N/A      2.4 L      0.230      0.243      0.218    0.187 L    3 0.222      0.303    4 0.31
--------------------------------------------------------------------------------------------------------------------------------------------------------
1 J: Estimated result, due to poor field duplication.
2 L: Qualified result with a low bias for positive result.
3 Average of duplicate sample results.
4 HBL for hydrogen cyanide.

How Was the Groundwater Ingestion Risk Assessment Established?
    We assessed the off-site landfill scenario for the ammonia recycle 
filter cartridges, reflecting the types of management reported for this 
waste. We assessed the groundwater ingestion pathway for these 
landfills. Our model inputs included different hydrogeologic settings 
reflecting the two regions where the wastes are reported to be managed. 
As noted in section III.C., we used the TCLP results for the municipal 
landfill scenario and the SPLP for the industrial landfill scenario.
    As described above, we had some initial concerns about our 
analytical data and determined that re-analysis would serve to 
demonstrate the validity of these data. Due to the time constraints of 
this listing determination, we could not delay the risk assessment 
modeling until the validated results of the second round of analyses 
became available, and thus used the first round of samples for the 
Texas facility as model input. Subsequently, having reviewed all the 
analytical data, we believe that the modeled data set appropriately 
characterizes the risks of

[[Page 55721]]

all constituents included in the first sampling round, and that re-
running the model with the second round of analytical data would not 
increase the predicted risk. The only additional constituent of concern 
found in the second analysis was cadmium. We modeled this constituent 
using the same two scenarios and found no significant risk.
What is EPA's Listing Rationale for This Waste?
    The results of our probabilistic risk assessment are provided in 
Table III-13 below (we also completed deterministic risk modeling and 
the results were comparable; see ``Risk Assessment for the Listing 
Determinations for Inorganic Chemical Manufacturing Wastes'' for 
details). At the 90th and 95th percentile cumulative risk level, we 
found no cancer risk in excess of 1E-07, nor did we find any hazard 
quotients that exceeded one. As a matter of policy, we generally do not 
consider listing wastes with predicted cancer risks of less than 1E-06 
or hazard quotients of less than 1.0. We see no special concerns 
warranting an exception to this policy. Based on these results we 
conclude that this waste does not pose risk to human health and the 
environment at levels that warrant listing. We therefore are proposing 
not to list ammonia recycle filters from inorganic hydrogen cyanide 
production.

                      Table III-13.--Groundwater Risk Results for Ammonia Recycle Filters 1
----------------------------------------------------------------------------------------------------------------
                                            Antimony                   Arsenic                   Cadmium
                                   -----------------------------------------------------------------------------
            Percentile                                           Adult        Child
                                      Adult HQ     Child HQ   cancer risk  cancer risk    Adult HQ     Child HQ
----------------------------------------------------------------------------------------------------------------
Industrial Landfill:
    90th..........................      7.9E-02      1.6E-01      3.8E-08      2.8E-08      3.6E-04      7.7E-04
    95th..........................      1.9E-01      3.9E-01      1.6E-07      1.2E-07      1.6E-03      3.4E-03
Municipal Landfill:
    90th..........................      8.7E-02      1.8E-01      3.9E-08      3.1E-08      4.0E-04      8.5E-04
    95th..........................      2.0E-01      4.2E-01      1.8E-07      1.3E-07      1.7E-03     3.7E-03
----------------------------------------------------------------------------------------------------------------
1 Modeling for two other constituents (nickel and cyanide) yielded HQs that were extremely small (1E-16) even at
  the 95th%.

    (3) Biological wastewater treatment solids.
How Many Facilities Generate This Waste Category and How Is It Managed?
    Four facilities reported a total volume of 45,397 MT/year for this 
waste. The management methods reported are off-site municipal and 
industrial Subtitle D landfills, on-site Subtitle C landfill, and off-
site use as agricultural liming agent (volume not reported).
What Management Scenarios Were Assessed?
    We evaluated the Subtitle D landfill and the agricultural liming 
agent scenario reflecting the reported management practices. We 
assessed the landfill scenario using our TCLP and SPLP results for the 
wastes reported managed in such landfills. We assessed the agricultural 
use scenario by comparing total constituent concentrations to the soil 
screening levels (see section III.C.3).
How Was This Waste Category Characterized?
    We collected two samples of this waste at two different facilities. 
We conducted total and leaching analyses of these samples. To evaluate 
the industrial landfill disposal scenario we compared the SPLP leaching 
results to constituent HBLs, and for the municipal landfill scenario we 
compared TCLP leaching results to the HBLs. In all cases the SPLP and 
TCLP levels corresponding to the management practice were below the 
HBLs.
    For the agricultural liming scenario, we compared the total 
concentrations in the waste to the soil screening levels; no 
constituents exceeded these screening levels, i.e., all constituents 
were below background or direct soil ingestion levels.
    The full analyses are summarized in the ``Inorganic Hydrogen 
Cyanide Listing Background Document for the Inorganic Chemicals Listing 
Determination'' and the analytical results are reported in detail in 
the Waste Characterization Reports for this sector; these documents are 
available in the docket for today's proposal.
What Is EPA's Listing Rationale for This Waste?
    We propose not to list this waste as hazardous because the levels 
of toxicant constituents found in the waste are below the levels of 
concern.
    (4) Feed gas cartridge and spent carbon filters.
How Many Facilities Generate This Waste Category and How Is It Managed?
    Nine facilities reported a total volume of 9.7 MT/year for this 
waste. The management methods reported are off-site manufacturer 
refurbishing for reuse, off-site municipal D landfill, off-site 
industrial D landfill, and on-site C hazardous landfill. The facility 
using the hazardous C landfill for disposal of the filters is managing 
the filters as nonhazardous waste in a captive on-site C landfill.
What Management Scenarios Were Assessed?
    We assessed the municipal and industrial Subtitle D landfill 
scenarios using our TCLP and SPLP results, respectively. No volatile 
constituents were detected in this waste (only non-volatile metals were 
detected; see following section), thus volatilization from landfills to 
the air was not a pathway of concern. We did not assess the voluntary 
Subtitle C landfill scenario because we assumed that listing would not 
significantly increase regulatory control. Note that the on-site unit 
has sufficient capacity to continue to accept this small volume waste.
How Was This Waste Category Characterized?
    We collected one sample of this waste. The analytical results 
showed that SPLP levels for all constituents are below drinking water 
HBLs. The TCLP results showed levels that exceeded HBLs for the 
constituents summarized below in Table III-14:

[[Page 55722]]



                Table III-14.--Characterization of Feed Gas Filters From Inorganic HCN Production
                                                 [mg/kg or mg/L]
----------------------------------------------------------------------------------------------------------------
                         Constituent                             Total         TCLP         SPLP         HBL
----------------------------------------------------------------------------------------------------------------
Boron.......................................................       17,900          7.4          0.5          1.4
Lead........................................................         18.5       1 0.03      1 0.003        0.015
Nickel......................................................         91.0          0.4         0.05         0.31
Zinc........................................................        1,060           13          0.5           5
----------------------------------------------------------------------------------------------------------------
1 Results are less than the typical laboratory reporting limit, but are greater than the calculated instrument
  detection limits.

    Split sample results provided by the facility were comparable. We 
did not find cyanide in these wastes.
    The full analytical results are summarized in the ``Inorganic 
Hydrogen Cyanide Listing Background Document for the Inorganic 
Chemicals Listing Determination'' and are reported in detail in the 
Waste Characterization Reports for this sector; these documents are 
available in the docket for today's proposal.
How Was the Groundwater Ingestion Risk Assessment Established?
    We assessed the groundwater ingestion pathway for the off-site 
landfill scenario for this waste, reflecting the types of management 
reported. As noted in section III.E., we used the TCLP results for the 
municipal landfill scenario and the SPLP for the industrial landfill 
scenario. We found that the industrial Subtitle D landfill scenario 
screened out because all constituents in the SPLP analysis were below 
their respective HBLs.
    The constituents of concern that exceeded their respective HBLs in 
the TCLP results were boron, lead, nickel, and zinc. We evaluated these 
constituents using the de minimis volume screening analysis, as 
described in section III.E.3 of today's proposal. The analysis suggests 
that lead, nickel and zinc are not of concern. We modeled the remaining 
constituent, boron, using our standard groundwater model for the 
municipal landfill scenario. We modeled the municipal landfill 
scenario, using a hydrogeologic setting reflecting the region where the 
waste was reported to be managed.
What Is EPA's Listing Rationale for This Waste?
    As noted above, the industrial landfill scenario screened out. For 
the municipal landfill scenario, the results in Table III-15 show that 
the HQs are well below one at both the 90th and 95th% for the 
constituent of concern. Thus, our risk assessment results suggest that 
the only constituent of concern that required modeling (boron) does not 
pose a substantial present or potential hazard to human health and the 
environment. For a more complete description of this analysis, see 
``Risk Assessment for the Listing Determinations for Inorganic Chemical 
Manufacturing Wastes' in the docket. Thus, we propose not to list this 
waste as hazardous.

 Table III-15.--Groundwater Risk Results for Feed Gas Filters for Boron
------------------------------------------------------------------------
                                                           Adult   Child
                       Percentile                           HQ      HQ
------------------------------------------------------------------------
90th....................................................   0.007    0.01
95th....................................................    0.01    0.05
------------------------------------------------------------------------

    (5) Process air cartridge filters.
How Many Facilities Generate This Waste Category and How Is It Managed?
    Eight facilities reported a total volume of 7.5 MT/year for this 
waste. The management methods reported are off-site industrial D 
landfill, off-site manufacturer refurbishing for reuse, off-site 
municipal D landfill, and on-site industrial D landfill. Most 
facilities reported the practice of filtering the air that they feed to 
the reactors. Very small volumes of spent filters are generated 
periodically. We did not assess these wastes beyond the 
characterization provided in the RCRA Section 3007 Survey results 
because no wastes were available to sample when we conducted our 
sampling. The level of toxic constituents is expected to be low because 
the filters are only used to remove airborne solids from the ambient 
air used in the process.
What Is EPA's Listing Rationale for This Waste?
    We propose not to list this waste as hazardous because we do not 
believe that the level of any toxic constituents in these small waste 
volumes would exceed levels of concern that would pose a risk based on 
management in Subtitle D landfills.
    (6) Acid spray cartridge filters.
How Many Facilities Generate This Waste Category and How Is It Managed?
    One facility reported a total volume of 1.1 MT/year for this waste. 
The management method reported was on-site Subtitle C disposal as a 
nonhazardous waste. The cartridge-type filter elements are used in the 
process to prevent clogging of spray nozzles used to inject the 
hydrogen cyanide intermediate product into the HCN stripper. The 
filters remove process particulates, including rust, from the hydrogen 
cyanide intermediate product. The waste is generated when the spent 
filter elements are replaced weekly. While this waste is classified as 
nonhazardous, the generator disposes of it in the facility's on-site 
Subtitle C landfill.
How Was This Waste Category Characterized?
    No sample of this waste was collected because of unavailability 
during the sampling time frame and because the level of toxic 
constituents is expected to be low. The filters are used to remove 
inert impurities such as pipe scale. The facility washes the filters 
prior to removal of the filters from the process. We expect that any 
hydrogen cyanide contamination is removed during this washing. The 
facility reported in its RCRA Section 3007 Survey that the waste 
contains a total concentration of cyanide of one ppm.
What Is EPA's Listing Rationale for This Waste?
    We propose not to list this waste as hazardous because the level of 
toxic constituents found in this waste are expected to be below levels 
of concern. While we do not have any leaching test data, we can 
conservatively estimate that any leachable level of cyanide would be at 
least 20-fold less than the 1 ppm total level reported, i.e, less than 
0.05 mg/L. This is well below the HBL for amenable cyanide (0.3 mg/L). 
Furthermore, this small volume waste is already managed in a Subtitle C 
landfill.
    (7) Spent catalyst. All ten facilities reported generation of this 
waste, with a combined total volume of 4.1 MT/year. The management 
method reported was off-site metals reclamation or regeneration. These 
catalysts gradually lose their effectiveness over time and are 
periodically reclaimed. Due to the

[[Page 55723]]

high value of these precious-metal materials, generators maintain close 
control over these materials. The spent material is an impermeable 
metal gauze that undergoes thorough cleaning and decontamination to 
eliminate cyanide concentrations prior to removal from the reactor. We 
have chosen not to evaluate these materials further because management 
practices for these materials prior to reuse minimize the potential for 
environmental releases. Therefore, we propose not to list this waste as 
hazardous because there are no significant known exposure pathways that 
would present risk.
    (8) Ammonium sulfate and ammonium phosphate.
How Many Facilities Generate This Waste Category and How Is It Managed?
    Three facilities reported a total volume of 27,425 MT/year for this 
waste. The management method reported was off-site use as fertilizer.
What Management Scenarios Were Assessed?
    We assessed the agricultural end use of this waste by comparing the 
total constituent results to the soil screening levels. In this case we 
evaluated the material, because it is land applied.
How Was This Waste Category Characterized?
    One sample of this by-product was collected from the Alabama site. 
The analytical data results show that the detected constituents of 
concern in the total analyses are below the soil screening levels. In 
addition, we compared the SPLP leaching results to the HBLs as a screen 
of potential groundwater exposure.\39\ The detected SPLP results are 
below the HBLs. The analytical results showing the level of toxic 
constituents are included in the ``Inorganic Hydrogen Cyanide Listing 
Background Document for the Inorganic Chemicals Listing 
Determination.''
---------------------------------------------------------------------------

    \39\ Note that the SPLP/HBL groundwater screen for this scenario 
is likely to be a worse-case screening, because the fertilizer 
application scenario isn ot analogous to a landfill scenario, 
particularly with respect to application rates.
---------------------------------------------------------------------------

What Is EPA's Listing Rationale for This Waste?
    We propose not to list this waste as hazardous because the levels 
of toxic constituents found in the waste are below levels of concern.
    (9) Miscellaneous wastewaters.
How Many Facilities Generate This Waste Category and How Is It Managed?
    Four facilities reported a total volume of 209,000 MT/year for this 
waste category; the total volume represents twenty two different 
miscellaneous wastestreams that are generated on an intermittent or 
periodic basis. The management method reported was commingling with 
other major process wastewater streams described above as the 
``commingled wastewaters'' category.
What Management Scenarios Were Assessed?
    We did not assess these numerous wastewater streams individually. 
The wastewaters were assessed indirectly within the commingled 
wastewater category discussed earlier. The volume and constituents 
represented by these miscellaneous wastewaters are represented in the 
total commingled major and miscellaneous wastewater streams.
How Was This Waste Category Characterized?
    We did not collect samples of these miscellaneous wastewater 
streams. The levels of toxic contaminants in these wastewaters are 
reflected in the contaminant concentrations of the total commingled 
wastewater streams at each facility. See the commingled wastewater 
category discussed earlier in this section for a discussion on how the 
commingled major and miscellaneous wastewater streams were 
characterized. Two of the miscellaneous wastewaters were reported to 
contain potentially high concentrations of hydrogen cyanide when 
generated.
What Is EPA's Listing Rationale for This Waste Category?
    We propose not to list this waste category as hazardous. There is 
no direct exposure pathway into the environment from these individual 
wastes, because they are treated and commingled with the other 
wastewaters generated at each facility. Although high concentrations of 
hydrogen cyanide in the wastewaters are possible for some of these 
wastes, the risk is reduced by the high dilution that occurs when these 
wastewaters are mixed with other large volume wastewaters in the 
facility-wide wastewater collection system. These miscellaneous 
wastewaters are generated intermittently and infrequently. Thus, any 
potential releases from land-based management of the wastes after 
dilution in with other wastewaters would be short-lived, and unlikely 
to result in any significant long-term risk. In addition, the hydrogen 
cyanide contaminant is readily and rapidly treated in the wastewater 
treatment systems, so that any risk is minimized. For example, the tank 
farm scrubber water from the Tennessee facility is treated through 
oxychlorination, which rapidly destroys the hydrogen cyanide. As noted 
earlier, potential hydrogen cyanide releases via the air pathway would 
be covered by the Hydrogen Cyanide MACT rule.
    (10) HCN polymer and HCN sump wastes. One facility reported a total 
volume of 0.7 MT/year (0.3 MT/yr polymer and 0.4 MT/year sump wastes) 
for these two wastes. The physical description of the wastes was 
reported as dirt, debris and inert polymer solids. The wastes are 
disposed of in an off-site industrial Subtitle D landfill. Very small 
volumes of these wastes are generated periodically. We did not assess 
these wastes beyond the characterization provided in the RCRA Section 
3007 Survey results because of the unavailability under the sample 
schedule and because of the low concentrations of toxic constituents 
expected to be present in this waste.
    In the RCRA Section 3007 Survey, the one generator reported that 
total levels of cyanide were 50 mg/kg for the HCN polymer and 5 mg/kg 
for the sump wastes. These levels are unlikely to pose a risk in a 
landfill scenario for these very small waste volumes. In support of 
this, we note here, as we did above for the acid spray filter cartridge 
waste category, leaching test results would be at least 20-fold less 
than the total levels. This would mean any leaching from sump waste 
would be below the HBL for cyanide. While this 20-fold factor would 
leave the HCN polymer somewhat above the HBL at 2.5 ppm cyanide, we 
note that groundwater modeling for cyanide for the ammonia recycle 
filters indicates similar levels of cyanide in a larger waste volume 
presents very low levels of risk in a landfill scenario. Therefore, we 
propose not to list HCN polymer and HCN sump wastes.
    (11) Sludge from wastewater collection tank. One facility reported 
a volume of 2.1 MT over a seven year period, or approximately 0.3 MT/
year for this waste. The waste was coded as hazardous (D001), 
stabilized on-site and disposed of in an off-site Subtitle C landfill. 
The waste is generated approximately every ten years; the volume 
reported was for 1993 with no generation of that waste since that date. 
This waste results from sedimentation in a wastewater collection tank. 
HCN wastewaters managed in this tank only account for ten percent of 
throughput; the sediment thus is only marginally associated with HCN 
production. One other facility reported generating 1.8 MT of this 
waste, and also codes it as characteristically hazardous waste (in this 
case as D018 for benzene). This

[[Page 55724]]

second facility sends the waste off-site to a Subtitle C incinerator; 
the facility reported that the benzene was derived from other on-site 
processes. We propose not to list these wastes because they are very 
small volume wastes that are already managed as characteristically 
hazardous wastes in full compliance with the Subtitle C regulations. In 
addition, the wastes are generated from the treatment of predominantly 
non-HCN wastewater from unrelated petrochemical processes at the 
facilities.
    (12) HCN storage tank solids. One facility reported a volume of 0.3 
MT/year for this waste. During periodic shutdowns of this product tank 
for cleaning, solids are removed after rigorous washing of the tank 
interior to remove soluble cyanide. The waste consists of polymer and 
tank scale. The waste is disposed of in an off-site municipal Subtitle 
D landfill. A sample of this waste was not collected because of 
unavailability during the sampling time frame. However, the waste 
description provided by the facility indicates the waste is similar in 
composition to the ammonia recycle filters, which we have proposed not 
to list. Given the much smaller volume here, this waste is not expected 
to present significant risk. Therefore, we are proposing not to list 
this waste as hazardous.
    (13) Wastewater filters. One facility reported a volume of 450 MT/
year for this waste. The waste is managed in a captive, off-site 
Subtitle C incinerator as characteristically hazardous waste. The waste 
is spent filters from the filtration of commingled wastewaters from 
various on-site processes prior to on-site deepwell injection and is 
generated periodically. A sample of this waste was not available during 
the sampling time frame. However, the one generator reported that the 
waste is characteristically hazardous due to benzene, and the facility 
manages the waste as D018. The source of the benzene is the waste from 
other non-HCN process wastewaters at the facility. We propose not to 
list this waste because it is already managed as a hazardous waste in 
accordance with Subtitle C regulations.
    (14) Ammonium sulfate filters. One facility reported a volume of 
1.1 MT/year for this waste. The waste is managed in an off-site 
industrial landfill. The waste is generated periodically. We did not 
assess this waste beyond the characterization provided in the RCRA 
Section 3007 Survey results because of the unavailability of samples 
under the sample schedule. However, the facility reported 
concentrations of cyanide (1 mg/kg) and ammonium sulfate (5,000 mg/kg). 
This concentration of cyanide is considered to be very small and is not 
expected to be of concern (see discussion of cyanide for acid spray 
cartridge filters). In addition, we collected a sample of the ammonium 
sulfate by-product (i.e., the material being filtered to generate this 
waste) and did not find any constituents of concern. See discussions 
for ammonium sulfate and ammonium phosphate. Therefore, we propose not 
to list this waste as hazardous because we do not believe that there 
are any significant levels of toxic constituents in the waste.
    (15) Spent ammonium phosphate. One facility reported a volume of 
230 MT/year for this waste. The waste is reused on-site as a nutrient 
source in the biological treatment unit or incinerated on-site in a 
nonhazardous waste incinerator. The waste is generated in batches one 
or two times per year. The waste is generated from the scrubbing of the 
reactor off-gas stream using aqueous monoammonium phosphate solution in 
the ammonia recovery process. The resulting diammonium phosphate 
solution is then purified to recover the ammonia and the resulting 
spent ammonium phosphate solution is stored in tanks prior to final 
management. We did not assess this waste beyond the characterization 
provided in the Sec. 3007 Survey results because of the unavailability 
of samples under the sample schedule; the characterization indicates 
the presence of organonitrile compounds in the waste. However, the 
preferred management method is to reuse the waste as a nutrient source 
in the biotreatment system, with incineration only when this is not 
possible due to the solution becoming spent or when the concentrations 
of phosphate and ammonia are incompatible with the wastewater treatment 
system. We believe the levels of organonitrile compounds do not pose a 
risk under either management scenario. The wastewater treatment 
scenario results in the destruction of the compounds via biodegradation 
and the incineration scenario would also result in destruction of the 
volatile organonitriles. Additionally, emissions from the on-site 
incinerator would be regulated under the Hydrogen Cyanide MACT 
standards which will be proposed in 2000. Therefore, we propose not to 
list this waste as hazardous.
    (16) Organic layer from wastewater collection tank. One facility 
reported a volume of 43.3 MT/year for this waste. The waste is coded as 
D001 and sent off-site Subtitle C incineration. This waste is generated 
approximately every ten years; the volume reported was for 1993 with no 
generation of the waste since that date. Thus, on an annualized basis 
the waste quantity generated would be approximately 4 MT/yr. We did not 
assess these wastes beyond the characterization provided in the RCRA 
Section 3007 Survey results because of the unavailability of samples 
under the sample schedule. We propose not to list this waste as 
hazardous because the waste is managed as characteristically hazardous 
in accordance with all applicable Subtitle C standards, which 
adequately protect against mismanagement. Further, the waste is 
generated from the treatment of predominantly non-HCN wastewater from 
other unrelated petrochemical processes at the facility. Only ten 
percent of the wastewater throughput in the tank generating this waste 
is associated with HCN production; the percentage contribution from the 
HCN process to this oily layer is likely to be much lower, because 
other petrochemical processes on-site are likely sources of the organic 
material.
6. Phenyl Mercuric Acetate
    a. Summary. We propose not to list any wastes from the production 
of phenyl mercuric acetate (PMA) as hazardous under Subtitle C of RCRA. 
PMA currently is not manufactured in the United States, and it is 
extremely unlikely that it will be manufactured in the United States in 
the future. Therefore, there are no wastes being generated that could 
be subject to a listing determination.
    b. Description of the phenyl mercuric acetate industry. PMA 
(C8H8Hg O2) is an organic mercury 
compound, a white to creamy white odorless crystalline powder or clear 
solution. Prior to 1990 it was the predominant fungicide used in the 
latex paint industry. In 1990, EPA banned the use of PMA in interior 
paint (55 FR 26754, June 29, 1990) and subsequently, the paint industry 
ceased using PMA in paint production. PMA is still used for other 
limited purposes (e.g., slimicide in paper mills; selective herbicide 
for crabgrass; fungicide for diseases of turf on golf greens and tees; 
fungicidal seed dressing for seed- and soil-borne diseases of cereals, 
sorghum, and groundnuts).
    Based on our research and the results of our RCRA Section 3007 
Survey, we conclude that there is no domestic production of PMA. Any 
domestic demand is met by imports from other countries. See the 
``Phenyl Mercuric Acetate Listing Background Document for the Inorganic 
Chemical Listing Determination'' for details.

[[Page 55725]]

    c. Agency evaluation. PMA is not produced within the United States 
and is not widely used in domestic manufacturing processes. Therefore, 
we have no reason to believe that wastes from the production of PMA are 
generated within the U.S. Given the compound's limited market within 
the U.S., it is highly unlikely that new production of PMA will occur 
within the U.S. in the future. As a result of these market conditions, 
there are no wastes that can be assessed for this sector. Therefore, we 
propose not to list any PMA production wastes as hazardous.
7. Phosphoric Acid From the Dry Process
    a. Summary. We have evaluated the wastes from the production of 
phosphoric acid manufactured via the dry process, and propose not to 
list any wastes from this process as hazardous wastes. These 
wastestreams do not meet the criteria set out at 40 CFR 261.11(a)(3) 
for listing wastes as hazardous. They do not pose a substantial present 
or potential threat to human health or the environment. We have 
identified no risks of concern associated with the current management 
of these wastes.
    b. Description of the phosphoric acid industry.
    Phosphoric acid was produced by the dry process by eight facilities 
in the United States in 1998. The majority of phosphoric acid is 
consumed in the manufacture of phosphate salts. These phosphorus-
containing compounds are used in detergents, animal feed supplements, 
dentifrices, fertilizers, metal treating, water softening, leavening 
agents, and flame and fire retardants.
    In the dry process, elemental phosphorous is burned in excess air 
generating phosphorous pentoxide (P2O5). The 
resulting phosphorus pentoxide is hydrated with a spray of recycled 
phosphoric acid and water, forming phosphoric acid that is collected as 
product. Scrubbers are employed for the hydrator off-gases to absorb as 
much phosphoric acid mist as possible from the excess air. The strong 
phosphoric acid stream from the hydrator is purified with hydrogen 
sulfide to precipitate out arsenic trisulfide. This sludge is removed 
by filtration. In some cases, off-specification product is filtered and 
recycled into the process. The product may also be filtered after it 
leaves the storage tank and prior to loading in truck and railcars.
    c. Description of wastes generated by the phosphoric acid process. 
We have identified fourteen waste categories from the production of 
phosphoric acid (via the dry process) that required assessment. These 
waste categories are described briefly and in more detail in the 
following subsections.\40\
---------------------------------------------------------------------------

    \40\ One facility has shut down their phosphoric acid process 
and reported few wastes generated in 1998. This facility's wastes 
therefore are not included in the following overview, but were 
evaluated to determine their potential threat to human health or the 
environment. The details of this facility's waste generation and 
management practices are included in the ``Phosphoric Acid Listing 
Background Document for the Inorganic Chemical Listing 
Determination''.

--Arsenic filter cake is the result of filtering the phosphoric acid 
after the addition of sodium hydrosulfide or hydrogen sulfide gas and a 
filter aid. The precipitate consists of arsenic trisulfide and other 
heavy metal sulfides which are essentially insoluble in strong acid.
--Combustion chamber slag (infrequently generated) is the result of 
residue buildup on the walls of the chamber.
--Off-specification phosphoric acid is generated when the product does 
not meet color or concentration specifications.
--Spent filters (from purification) are generated from the units that 
are used to remove arsenic from the phosphoric acid.
--Caustic scrubber water is generated when air used to remove hydrogen 
sulfide gas at the acid purification step is scrubbed. This scrubbing 
operation controls odor and acid mist before the air is discharged to 
the atmosphere.
--Phosphoric acid spills occur around the process or storage tanks 
area. These materials are collected in contained areas and pumped to 
management units.
--Clean-up and washdown water from across the units is collected in a 
sump and discharged to the wastewater treatment system.
--Process acid leaks occur when piping and coupling break, or during 
equipment maintenance. These materials are collected in contained areas 
and pumped to management units.
--Spent mist eliminator packing (filters) are used in the scrubber 
system to remove gas and acid particulates from the phosphoric acid. 
The filter packing material is reported to consist of polyester fibers, 
stainless steel, steel wool or fiberglass. The filters are periodically 
replaced and the spent packing is washed prior to disposal.
--Rubber liners of product storage tanks are periodically replaced.
--Spent filters for product are generated when product is filtered 
prior to loading into tank cars and trucks to remove settled solids. 
The filters are changed periodically and rinsed with water prior to 
disposal.
--Spent activated carbon for off-specification product is generated 
when carbon is used to remove traces of contaminants from the off-
specification product.
--Spent filters for off-specification product is generated when filters 
are used to remove solids from the off-specification product.
--Wastewater treatment sludges are generated when wastewaters from the 
phosphoric acid and other processes are treated. These sludges are only 
marginally derived from phosphoric acid wastewaters due to commingling 
with large volumes of other non-phosphoric acid wastewaters. The solids 
that are removed by filtration are landfilled or sold.

    Three facilities reported that they collect phosphoric acid in air 
pollution control devices (i.e., vent scrubbers, absorbers, mist 
eliminator). Each site reported that they then recycle these acids into 
the production process. This material is continuously reused in the 
production process. Based on our site visits, the material is piped 
from the generating unit to the production process, minimizing the 
potential for releases to the environment prior to reuse. We evaluated 
all wastes generated after the materials are reused and concluded that 
none merited listing. Consequently, we do not believe that these 
materials present significant threats.
    At two of the facilities, the caustic scrubber water, generated 
from scrubbing the air to remove hydrogen sulfide gas, is returned as 
makeup solution to the purification process. Based on information from 
one of the facilities and our site visit, the material is piped from 
the generating unit to the production process, and there is no 
significant potential for exposure. Also, process acid leaks are 
collected in tanks at one facility and piped back to the acid process, 
with no significant exposure route for this material. As stated above, 
we evaluated all wastes generated after the materials are reused and 
concluded that none merited listing. Consequently, we do not believe 
that these materials present significant threats.
    We have organized our discussion of these wastes in terms of how 
they are currently managed: characteristic wastes, wastewaters, and 
non-characteristic solid wastes.

[[Page 55726]]

    d. Agency evaluation. (1) Characteristic wastes. The RCRA Section 
3007 Surveys show that a number of wastes are managed as RCRA 
characteristic wastes at all times. These wastes are hazardous wastes 
because they exhibit the characteristics of corrosivity or toxicity for 
arsenic. We believe that these wastes are managed according to the 
applicable RCRA Subtitle C regulations, including LDR standards. The 
LDR restrictions apply prior to land disposal. Furthermore, these 
wastes are managed or disposed in Subtitle C management units. Table 
III-16 summarizes our information regarding the generation and 
management of these wastes.

        Table III-16.--Characteristic Wastes From Phosphoric Acid Production Disposed in Subtitle C Units
----------------------------------------------------------------------------------------------------------------
                                       Number of
          Waste category               reported       1998 Volume   Reported hazard codes     Final management
                                      generators         (MT)                                    practices
----------------------------------------------------------------------------------------------------------------
Arsenic filter cake...............               7             614  D002, D004...........  Subtitle C landfill
Combustion chamber slag...........               1             0.1  D002.................  Subtitle C
                                                                                            incineration
Off-specification phosphoric acid.               1            0.71  D002.................  Subtitle C landfill
Spent filters (from purification).               2             4.6  D004.................  Subtitle C
                                                                                            incineration or
                                                                                            Subtitle C landfill
----------------------------------------------------------------------------------------------------------------

    We propose not to list these four waste categories as hazardous 
wastes under RCRA. All generators of these wastes already report 
managing these materials as hazardous from the point of generation 
through disposal, because they exhibit one or more of the hazardous 
waste characteristics. We believe that the rules applying to 
characteristic wastes adequately protect against mismanagement.
    (2) Other characteristic waste.

                Table III-17.--Other Characteristic Wastes from the Production of Phosphoric Acid
----------------------------------------------------------------------------------------------------------------
                                       Number of
          Waste category               reported       1998 Volume   Reported hazard codes  Sequential management
                                      generators         (MT)                                    practices
----------------------------------------------------------------------------------------------------------------
Phosphoric acid spills............               2             2.2  D002.................  (1) Neutralized, (2)
                                                                                            roll-off bin, (3)
                                                                                            Subtitle D landfill;
                                                                                           (1) Tanks, (2)
                                                                                            neutralized in
                                                                                            surface impoundment,
                                                                                            (3) NPDES
----------------------------------------------------------------------------------------------------------------

    We assessed the specific management practices employed for this 
wastestream, as summarized in Table III-17, and determined that no 
exposure scenarios of concern exist. One facility reported that the 
wastestream is managed as hazardous (D002), neutralized, and disposed 
of in a Subtitle D landfill. These product spills are expected to be 
mostly phosphoric acid, which is hazardous because it is corrosive. The 
facility effectively treats and neutralizes these wastes prior to 
disposal. There is no significant risk expected from the disposal of 
the small volume (0.5 MT/yr) of treated spills to the landfill.
    The second facility reported placing the untreated spills into its 
wastewater treatment system, which includes both tanks and 
impoundments. Again, we expect that this waste presents hazards because 
of its corrosivity, not because it contains hazardous constituents. We 
do not expect releases to groundwater from tanks because we assume that 
they function effectively. With regard to the surface impoundment, we 
note that the facility has estimated that these small volume spills 
make up less than 0.001% of the total wastewater volumes. We expect 
that dilution of this magnitude would effectively treat the spills 
rapidly. Further, the facility reported that the wastewaters in the 
impoundment are neutralized. Consequently, we do not anticipate that 
any potential releases from the surface impoundment would pose a 
significant threat to groundwater. Ultimately, the spills are 
discharged, along with the much larger volume of wastewaters generated 
on-site, to surface waters under a NPDES permit, which provides 
effective control and an exemption from RCRA regulations. We also note 
that we expect no release of constituents of concern to the air from 
either the tank or the impoundments, because the waste contains no 
volatile constituents.
    (3) Wastewaters. Wastewaters are generated at various points in the 
process as a result of scrubbing operations, equipment cleanup, and 
management of leaks and spills. As reported by the facilities, the 
primary constituents of concern in these wastewaters are phosphoric 
acid and traces of hydrogen sulfide, which are readily treated and 
controlled via neutralization. Phosphoric acid, when neutralized, forms 
various phosphate salts, none of which are known to pose a significant 
risk to human health and the environment. Similarly, hydrogen sulfide 
is neutralized to form nonvolatile salts. All facilities report that 
these wastewaters comprise very small portions of the overall 
wastewater treatment throughput, which contains wastewaters from other 
unrelated on-site processes. Table III-18 summarizes our information on 
these wastewaters.

                           Table III-18.--Wastewaters From Phosphoric Acid Production
----------------------------------------------------------------------------------------------------------------
                                      Number of                                                   Sequential
          Waste category              reported       1998 Volume     Reported hazard codes        management
                                     generators         (MT)                                      practices
----------------------------------------------------------------------------------------------------------------
Caustic scrubber water...........               1              36  none....................  (1) pretreatment in
                                                                                              covered tanks,
                                                                                             (2) POTW

[[Page 55727]]

 
Cleanup water....................               1    small volume  none....................  (1) pretreatment in
                                                      (volume not                             covered tanks,
                                                        reported)                            (2) POTW
Process acid leaks...............               1           25\1\  none....................  (1) pretreatment in
                                                                                              covered tanks,
                                                                                             (2) NPDES
----------------------------------------------------------------------------------------------------------------
\1\ The 25 tons include leaks from eight processes, of which one is phosphoric acid production. The individual
  volume of leaks from phosphoric acid production is unknown.

    We have assessed the management practices employed for these wastes 
and determined that no exposure pathway of concern exists. We believe 
these wastewaters will continue to be managed in existing tank-based 
treatment systems. We believe the manufacturers have made a 
considerable investment in wastewater treatment systems using tanks and 
will continue to use them. Further, we assumed that wastewater 
treatment tanks retain sufficient structural integrity to prevent 
wastewater releases to the subsurface (and therefore to groundwater), 
and that overflow and spill controls prevent significant wastewater 
releases. Thus, based on the lack of any significant likelihood of 
release of the constituents to groundwater, we did not project 
significant risks to groundwater from these wastes in the tank-based 
wastewater treatment scenario. Furthermore, discharges to POTWs and 
surface waters under NPDES are regulated under the Clean Water Act and 
are exempt from RCRA Subtitle C regulation and thus were not assessed.
    We also considered the possibility of air releases from tanks. The 
only potential volatile constituent of concern in these wastes is 
hydrogen sulfide. The treatment processes employed are designed to 
neutralize this compound, reducing the potential for volatilization. In 
addition, the facilities have installed tank covers, further reducing 
the likelihood of release to the air. As a result, we did not model 
releases to air from tanks from the production of phosphoric acid. 
Thus, we propose not to list these wastewaters as hazardous wastes 
under RCRA.
    (4) Non-characteristic solid wastes. The phosphoric acid sector 
reported six waste categories that do not routinely exhibit any of the 
hazardous waste characteristics and that are often managed in Subtitle 
D landfills, as summarized in Table III-19:

                                 Table III-19.--Non-characteristic Solid Wastes
----------------------------------------------------------------------------------------------------------------
                                      Number of                                                   Sequential
          Waste category              reported       1998 Volume     Reported hazard codes        management
                                     generators         (MT)                                      practices
----------------------------------------------------------------------------------------------------------------
Spent mist eliminator packing....               5            28.4  None....................  (1) storage in
                                                                                              containers, (2)
                                                                                              treatment to
                                                                                              control acid
                                                                                              (washing,
                                                                                              neutralization, or
                                                                                              off-site
                                                                                              stabilization by
                                                                                              one facility), (3)
                                                                                              recycling or
                                                                                              disposal in
                                                                                              Subtitle C or D
                                                                                              landfills.
Rubber liners....................               2            19.8  None....................  (1) storage in
                                                                                              containers, (2)
                                                                                              Subtitle C
                                                                                              incineration or
                                                                                              neutralization
                                                                                              before Subtitle D
                                                                                              landfill.
Spent filters for product........               1             0.5  None....................  (1) storage in
                                                                                              containers, (2)
                                                                                              off-site
                                                                                              stabilization, (3)
                                                                                              Subtitle D
                                                                                              landfill.
Spent activated carbon for off-                 1             1 3  None....................  (1) storage in
 specification product.                                                                       containers, (2)
                                                                                              off-site
                                                                                              stabilization, (3)
                                                                                              Subtitle D
                                                                                              landfill.
Spent filters for off-                          1             0.5  None....................  (1) storage in
 specification product.                                                                       containers, (2)
                                                                                              off-site
                                                                                              stabilization, (3)
                                                                                              Subtitle D
                                                                                              landfill.
Wastewater treatment sludges.....               3         2 0.005  None....................  (1) storage in
                                                                                              containers, (2)
                                                                                              Subtitle D
                                                                                              landfill.
----------------------------------------------------------------------------------------------------------------
\1\ 1996 volume; none generated in 1997 or 1998.
\2\ Two facilities did not report volumes due to very small input of phosphoric acid production wastes to the
  WWT system; one facility estimated that 0.0001% of 4,640 MT sludge generated (or 0.005 MT) was from phosphoric
  acid production.

    The spent mist filters collect phosphoric acid mist before arsenic 
trisulfide is precipitated out. The material which condenses in the 
filters is expected to be corrosive and may contain some arsenic. 
However, the material used for filter packing in the mist eliminators 
is typically polyester, fiberglass, or steel wool. The filter packing 
provides surface area for condensation, not absorption, and is not 
expected to accumulate waste or constituents. Thus, arsenic is not 
expected to adhere to the filters as condensate drops back into 
process. The generators treat the spent filters prior to disposal to 
remove or immobilize any low levels of constituents that may remain.
    The rubber liners and spent filters for product are associated with 
food-grade products. We expect any contaminant levels to be extremely 
low due to purity requirements. Consequently, we believe it is unlikely 
that they contain any constituent at levels of concern (i.e., above 
health-based limits for ingestion). We also note that both wastes are 
treated prior to disposal in landfills.
    Similarly, we do not expect the spent carbon or spent filters 
associated with off-specification product to contain significant levels 
of constituents of concern. Product is classified as ``off-
specification'' due to color and concentration of acid, rather than

[[Page 55728]]

because of the presence of any contaminants. We note again that these 
wastes undergo treatment prior to placement in landfills. In addition, 
both the activated carbon, which is infrequently generated, and the 
off-specification filters are very low volume wastes (on an annualized 
basis, the spent carbon totals about 1 MT and the spent off-
specification filters equal 0.5 MT).
    As stated in the wastewater rationale, the wastewater contribution 
from the phosphoric acid process is insignificant. Therefore, the 
volumes of treatment sludge (and any constituents of potential concern) 
attributable to the phosphoric acid process are small and unlikely to 
present any significant risk.
    We do not believe any of these materials contain significant 
concentrations of any contaminants of concern. Therefore, we propose 
not to list these wastes as listed hazardous wastes under RCRA.
8. Phosphorus Pentasulfide
    a. Summary. We have evaluated the wastes from the production of 
phosphorus pentasulfide and propose not to list any wastes from this 
process as hazardous. These wastestreams do not meet the criteria set 
out at 40 CFR 261.11(a)(3) for listing a waste as hazardous. They do 
not pose a substantial present or potential threat to human health or 
the environment. We have identified no risks of concern associated with 
the current management of these wastes.
    b. Description of the phosphorus pentasulfide industry. Phosphorus 
pentasulfide was produced by three facilities in the United States in 
1998. Phosphorus pentasulfide is used in the manufacture of lubricating 
oil additives, insecticides, ore flotation agents and specialty 
chemicals.
    The production of phosphorus pentasulfide begins by feeding liquid 
phosphorus and liquid sulfur into a reactor. The reaction is carefully 
controlled because phosphorus pentasulfide reacts violently with air 
forming phosphorus pentoxide and sulfur dioxide and because toxic 
hydrogen sulfide gas forms when phosphorus pentasulfide combines with 
moisture on exposure to air. To reduce this hazard, the process 
equipment is continuously purged with nitrogen. The phosphorus 
pentasulfide vapors are distilled and the liquid from the process is 
solidified, milled and packaged.
    One facility operates its entire process under nitrogen blanket. 
The blanketed vessels, packaging area and tote-bin wash systems are all 
vented to a caustic scrubber. A second facility vents the reactor to a 
caustic scrubber that removes the sulfur dioxide and hydrogen sulfide 
and generates a blowdown wastestream. The facility has other scrubbers 
that remove phosphorus pentoxide from the exhaust stream and reacts it 
with water to produce a dilute phosphoric acid that is routed to their 
acid plant. The third facility fills the reactor, condenser and 
packaging equipment with nitrogen to prevent oxidation. This nitrogen 
stream is scrubbed with recirculating water to remove phosphorus 
pentasulfide dust. The scrubber liquor is treated and discharged.
    c. Description of wastes generated by the phosphorus pentasulfide 
process. We have identified nine waste categories from the production 
of phosphorus pentasulfide that required assessment. These waste 
categories are described briefly and in more detail in the following 
subsections.

--Still residue/reactor waste is the result of impurities being left 
behind when the phosphorus pentasulfide is distilled to remove 
undesirables (high boilers). This residue consists of glassy 
phosphates, carbon, and iron sulfide compounds and is removed from the 
reactor during unit turn-around.
--Phosphorus pentasulfide scrap waste is occasionally generated during 
certain maintenance operations or equipment failure. This waste can 
also consist of commercial off-specification material and fugitive dust 
from the packaging operation.
--Absorbents contaminated with phosphorus pentasulfide and Therminol 
(benzylated ethyl benzene) are generated from cleaning up leaks during 
maintenance operations. The absorbent material may be in the form of 
floor dry (a granular material) or an absorbent pillow.
--Waste Therminol is a spent heat transfer product used for the vessels 
and pipes to prevent freeze up of the liquid phosphorus pentasulfide.
--Scrubber water is generated as a result of a nitrogen stream being 
scrubbed to remove phosphorus pentasulfide dust. The packaging 
equipment is filled with nitrogen to prevent oxidation.
--Caustic scrubber water is the result of the reactor, packing and tote 
bin wash system being vented to the scrubber to remove sulfur dioxide 
and residual hydrogen sulfide.
--Tote bin wash water results from cleaning the shipping containers 
that hold the product. The phosphorus pentasulfide residue is washed 
from the returned containers with water and caustic.
--Scrap sulfur is occasionally generated when making or breaking 
couplings to hoses where sulfur comes into the reaction.

    One facility reported that they filter elemental phosphorus before 
feeding it to the reactor. The filter solids, called phosphorus 
impurities, are managed in tanks and then are piped to that facility's 
phosphoric acid production furnace for phosphorus reclamation. Because 
there is low potential for significant exposure from on-site storage 
prior to entry in the furnace, we did not evaluate this material 
further under this sector. Note that wastes generated from the 
production of phosphoric acid via the dry process, including this 
facility's phosphoric acid furnace, are addressed in section III.F.7 of 
today's proposal.
    We have organized our discussion of these wastes in terms of how 
they are currently managed: characteristic wastes, wastewaters, and 
scrap sulfur.
    d. Agency evaluation. (1) Characteristic wastes. The RCRA Section 
3007 Surveys show that a number of the phosphorus pentasulfide wastes 
categories are managed as RCRA hazardous wastes at all times. These 
wastes are hazardous because they exhibit the characteristics of 
ignitability, reactivity or toxicity for chromium or benzene. The 
facility that generates the largest volume waste, phosphorus 
pentasulfide scrap waste, considers it to be a listed hazardous waste 
(U189). The surveys also show that these wastes are managed as 
hazardous wastes, with final disposition by incinerated in Subtitle C 
units. Table III-20 summarizes our information about these wastes.

[[Page 55729]]



    Table III-20.--Characteristic Wastes from Phosphorus Pentasulfide Production Disposed in Subtitle C Units
----------------------------------------------------------------------------------------------------------------
                                      Number of
          Waste category              reported       1998 volume     Reported hazard codes     Final management
                                     generators         (MT)                                      practices
----------------------------------------------------------------------------------------------------------------
Still residue/reactor waste......               2             4.6  D003, D007..............  Subtitle C
                                                                                              incineration.
Phosphorus pentasulfide scrap                   3           67.75  D001, D003, U189........  Subtitle C
 waste.                                                                                       incineration.
Contaminated absorbent...........               1      1.2 (1996)  D003....................  Subtitle C
                                                                                              incineration.
Waste Therminol..................               1             1.4  D018....................  Subtitle C
                                                                                              incineration.
----------------------------------------------------------------------------------------------------------------

    We propose not to list these four waste categories as hazardous 
wastes under RCRA. All generators of these wastes already report 
managing these materials as hazardous from the point of generation 
through incineration because they exhibited one or more of the 
hazardous waste characteristics. Again, the rules applying to 
characteristic wastes adequately protect against mismanagement. 
Furthermore, ninety percent of the waste are already listed as 
commercial chemical product (U189). Therefore, we propose not to list 
these wastes.
    (2) Wastewaters. Wastewaters are generated at various points in the 
process as a result of scrubbing operations and tote bin washing. As 
identified by the facilities, the primary constituents of concern in 
these wastewaters are phosphoric acid and hydrogen sulfide which are 
readily controlled via neutralization. The management practices for 
these wastewaters do not allow for the release of phosphoric acid and 
hydrogen sulfide to the environment in an undiluted or unneutralized 
state. Table III-21 summarizes our information on these wastewaters:

                       Table III-21.--Wastewaters From Phosphorus Pentasulfide Production
----------------------------------------------------------------------------------------------------------------
                                      Number of                                                   Sequential
          Waste category              reported       1998 Volume     Reported hazard codes        management
                                     generators         (MT)                                      practices
----------------------------------------------------------------------------------------------------------------
Process scrubber water...........               1          77,377  none....................  (1) Sewer,
                                                                                              (2) POTW
Caustic scrubber water...........               2           2,177  none....................  (1) Covered tanks,
                                                                                             (2) off-site
                                                                                              treatment,
                                                                                             (3) NPDES;
                                                                                             (1) Treatment in
                                                                                              covered tanks,
                                                                                              (2) POTW.
Tote bin wash water..............               2             188  (1) D003................  (1) Covered tanks,
                                                                   (2) none................   (2) off-site
                                                                                              treatment,
                                                                                              (3) NPDES;
                                                                                             (1) Treatment in
                                                                                              covered tanks,
                                                                                              (2) POTW.
----------------------------------------------------------------------------------------------------------------

    We assessed the management practices for these wastes and 
determined that no exposure pathway of concern exists. Thus, we propose 
not to list these wastes as listed hazardous wastes under RCRA. The 
covered tanks employed minimize potential for releases to groundwater 
and air. Discharges to surface waters under NPDES are exempt from RCRA 
regulation. Discharges to POTWs via the facility's common sewage line 
are excluded from RCRA (40 CFR 261.4(a)(1)(ii)).
    (3) Scrap sulfur. One facility reported generation of scrap sulfur 
that occasionally exhibits the characteristic of TC for lead. This 
sulfur is managed as hazardous in a Subtitle C incinerator. The 1998 
waste volume was 0.12 MT.
    We do not believe this material warrants listing as hazardous waste 
and, therefore, propose not to list this waste as hazardous under RCRA. 
While this waste category was reported to periodically exhibit a 
characteristic, the generator always manages the waste in a Subtitle C 
incinerator. We believe this management practice is likely to continue 
because the cost to treat it as hazardous is low for such a small 
volume wastes, and because the waste may be TC hazardous as generated. 
This waste is also small volume and highly unlikely to present a 
significant risk.
9. Phosphorus Trichloride
    a. Summary. We have evaluated the wastes from the production of 
phosphorus trichloride and propose not to list any wastes from this 
process as hazardous wastes. These wastes do not meet the criteria set 
out at 40 CFR 261.11(a)(3) for listing a waste as hazardous. They do 
not pose a substantial present or potential threat to human health or 
the environment. We have identified no risks of concern associated with 
the current management of these wastes.
    b. Description of the phosphorus trichloride industry. Six 
facilities in the United States reported producing phosphorus 
trichloride in 1997 or 1998. We are assessing wastes from the five 
facilities that still produce this product.\41\
---------------------------------------------------------------------------

    \41\ One facility discontinued production as of November 1999 
and has no future plans to resume production of phosphorus 
trichloride. This facility's wastes therefore are not included in 
the following overview, but were evaluated to determine their 
potential threat to human health or the environment. The details of 
this facility's waste generation and management practices are 
included in the ``Phosphoric Acid Listing Background Document for 
the Inorganic Chemical Listing Determination.''
---------------------------------------------------------------------------

    Phosphorus trichloride is used as an intermediate in the production 
of a variety of chemicals. These chemicals are used to make pesticides, 
herbicides, antiscaling additives, corrosion inhibitors for cooling 
towers and heat exchangers, surfactants, sequestrants, and textile-
treating agents. Phosphorus

[[Page 55730]]

trichloride is used as a raw material in the production of chemicals 
that are used extensively as lubricating oil additives to control 
corrosion and as antioxidants and flame retardants in plastics.
    Phosphorus trichloride (PCl3) is a clear, volatile 
liquid with a pungent, irritating odor. Phosphorus trichloride is 
produced by one basic process. Liquid phosphorus and chlorine gas are 
continuously introduced into a reaction vessel. The phosphorus 
trichloride vapor phase is purified in a packed column and then 
liquified in a condenser. Most raw material impurities remain in the 
reactor and are removed as solid waste periodically during unit 
turnaround. Some facilities filter the product before shipment to 
ensure there is no dirt or other particles in the final product.
    A scrubber is used to collect materials from various points in the 
process. For example, hydrochloric acid and phosphorus acid 
(H3PO3), the hydrolysis products of phosphorus 
trichloride vapors are vented to the scrubber from the reactor. Also, 
phosphorus trichloride vapor generated during transfer of the product 
into shipping containers is collected and vented to the same scrubber. 
The wastewater generated from the scrubber(s) is commingled with 
miscellaneous wastewaters (e.g., reactor washout, spent filter wash, 
process area wash water) and sent for treatment. Some facilities 
generate a wastewater treatment sludge from the cleanout of treatment 
tanks. All of these facilities produce a variety of other products that 
are outside the scope of today's rule, and they commingle the 
wastewaters from PCl3 production with wastewaters from other 
processes.
    c. What kinds of wastes are generated by this process?. We have 
organized our discussion of these wastes in terms of how they are 
currently managed: characteristic wastes, wastewaters, recycled 
phosphorus, and non-characteristic non-wastewaters. The wastes 
generated by this process include:

--Reactor cleanout sludge consists of impurities from the elemental 
phosphorus and chlorine raw materials, including high boiling 
impurities such as arsenic trichloride that are retained in the 
reactor. These materials are sent to Subtitle C incinerators.
--Initial washout water from reactor is generated as a result of 
rinsing out the reactor after sludge removal. In one case, the reactor 
is cleaned with hot water only and there is no initial sludge removal 
step. These materials are treated and discharged to an POTW and under a 
NPDES permit.
--Product storage tank cleanout with nonreactive phosphate ester is the 
rinsate generated from cleaning the storage tank or equipment. When 
this rinse is done, the rinsate is drummed for off-site disposal as a 
hazardous waste.
--Product storage tank cleanout with water is generated as a result of 
additional rinsing that follows phosphate ester rinsing. This 
potentially acidic rinse water is sent to wastewater treatment for 
neutralization.
--Spent filter washwater for product is generated as the result of 
washing the spent filters used to remove dirt and particles from the 
product. This wash water is mixed with other wastewaters and sent to 
wastewater pretreatment.
--Process area wash water consists of pad washdown/rain water and any 
spilled material collected in contained areas. This wash water is mixed 
with other wastewaters and sent to wastewater pretreatment.
--Final washout water from reactor is the rinsate from additional 
reactor washing after sludge removal. The one facility reporting this 
rinsate commingles it with other wastewaters prior to wastewater 
pretreatment.
--Caustic scrubber water consists of small amounts of sodium salts and 
residual caustic. Phosphorus trichloride, acid vapors, traces of 
chlorine and carbon dioxide are vented from various points of the 
process. The vent releases mixed with air are scrubbed before the air 
is released to the atmosphere. The spent scrubber charge is sent along 
with other wastewaters to wastewater pretreatment.
--Process scrubber water consists of a weak acidic solution from 
scrubbing residual gases from distillation and from various storage 
tank vents.
--Spent filters for product are generated due to filtering dirt and 
other particles from the product before shipment. The filters are 
washed and dried before disposal.
--Wastewater treatment sludges are generated when wastewaters from the 
phosphorus trichloride and other processes are biologically treated. 
These sludges are only marginally derived from phosphorus trichloride 
wastewaters due to commingling with large volumes of other non-
phosphorus trichloride wastewaters. The solids that are removed by 
filtration are landfilled.

    One facility reported recycling three secondary materials: 
phosphorous storage tank sediment; phosphorous transfer water; and 
absorber residual. The phosphorous storage tank sediment is generated 
periodically when the phosphorus storage tanks are cleaned. Because the 
material is stored in containers prior to being sent off-site for 
recovery of phosphorus we found low potential for significant exposure 
from on-site storage. The phosphorous recovery process is outside the 
scope of the consent decree so we did not evaluate its wastes. At this 
same facility, raw material phosphorous is unloaded from rail cars and 
conveyed through the facility using a closed pressurized piping system 
that uses water to push the phosphorous in the piping system. To unload 
the phosphorous from each rail car, water is pumped into the rail car 
to push the phosphorous out. Because the phosphorous/water filled rail 
cars are then returned to the phosphorous manufacturers, where the 
phosphorous is then recovered, we found no potential for significant 
exposure, and did not evaluate this material further. The third 
instance of recycling at this facility, gases vented from the product 
check, storage tanks, and reflux separator are collected in an 
absorber. The vapors from the absorber are captured in a caustic 
scrubber and sent to wastewater treatment (see wastewaters in section 
d(2) below). According to the facility, the non-vapor phosphorous 
trichloride residual from the absorber is collected and piped to a non-
consent decree production process where the phosphorous trichloride is 
incorporated into the non-consent decree product. Because this material 
is piped from the phosphorous trichloride process to the non-consent 
decree process, and there is no significant potential for exposure, we 
did not evaluate this residual further.
    d. Agency evaluation. We have organized our discussion of these 
wastes in terms of how they are currently managed: characteristic 
wastes, non-characteristic wastewaters, and non-characteristic solid 
wastes.
    (1) Wastes that are characteristically hazardous wastes. Many of 
the phosphorus trichloride producers stated that a number of their 
wastes exhibit RCRA characteristics. These wastes are hazardous wastes 
because they exhibit the characteristics of ignitability, corrosivity, 
reactivity or toxicity. The Toxicity Characteristic was reported for 
arsenic, cadmium, chromium, lead, mercury, selenium or silver.
    These characteristic wastes are subject to the applicable LDR 
standards. Furthermore, these wastes are

[[Page 55731]]

ultimately disposed in Subtitle C management units or as discharges 
regulated under the Clean Water Act. We believe that the applicable 
Subtitle C and Clean Water Act regulations adequately protect against 
mismanagement.
    Table III-22 summarizes our information about these wastes.

                   Table III-22.--Characteristic Wastes From Phosphorus Trichloride Production
----------------------------------------------------------------------------------------------------------------
                                      Number of                                                   Sequential
          Waste category              reported       1998 Volume     Reported hazard codes        management
                                     generators         (MT)                                      practices
----------------------------------------------------------------------------------------------------------------
Reactor cleanout sludge..........               4          \1\ 66  D001-004, D006-009,       (1) container
                                                                    D010, D011.              (2) Subtitle C
                                                                                              incineration
Initial washout water from                      4         \1\ 478  (1) D002, D004, D006,     (1) off-site
 reactor.                                                           D007.                     pretreatment,
                                                                   (2) D002, D004..........  (2) POTW;
                                                                   (3) D004, D007..........  (1) neutralized in
                                                                                              tanks,
                                                                                             (2) surface
                                                                                              impoundment,
                                                                                             (3) biotreat in
                                                                                              tank,
                                                                                             (4) NPDES;
                                                                                             (1) tank,
                                                                                             (2) off-site
                                                                                              biotreatment,
                                                                                             (3) NPDES
Product storage tank cleanout                   1              10  D002, D003..............  (1) container
 with nonreactive phosphate ester.                                                           (2) Subtitle C
                                                                                              incineration
Product storage tank cleanout                   1              15  D002....................  (1) neutralized in
 with water.                                                                                  tanks,
                                                                                             (2) NPDES
Spent filter wash for product....               1              15  D002....................  (1) pretreatment in
                                                                                              tanks,
                                                                                             (2) NPDES
Process area wash water..........               1           1,400  D002....................  (1) tanks,
                                                                                             (2) NPDES
----------------------------------------------------------------------------------------------------------------
\1\ Volumes from 1996 or 1997 are included in the totals when the wastes were not generated by a facility in
  1998.

    For all but one of the wastes in the above table, the generators 
report managing these materials as hazardous from the point of 
generation through disposal (or the point at which they become 
discharges to surface water regulated under NPDES or POTW regulations). 
We believe these wastes are sufficiently regulated such that 
mismanagement is unlikely. Thus, we propose not to list these seven 
waste categories.
    One facility appears to treat initial washout reactor water in 
tanks and then pass it through a nonhazardous waste surface 
impoundment. (All other units used to manage this waste have RCRA 
permits or are exempt from permitting.) While we have no analytical 
data on the treated waste that enters the impoundment, we do not 
believe this waste is likely to pose significant risk. The waste is 
generated infrequently (once a year) and combined with wastewaters from 
other processes. Based on information supplied by the facility, we 
estimated that the washout water would be diluted at least a hundred-
fold by the daily throughput to the wastewater treatment system. Any 
potential releases from the impoundment after dilution with other 
wastewaters would be unlikely to result in any significant long-term 
risk. Therefore, we believe that this specific waste also does not pose 
significant threats to human health or the environment.
    (2) Non-characteristic wastewaters. Wastewaters are generated at 
various points in the process as a result of scrubbing operations, 
equipment cleanup, and washing the process area. According to the data 
submitted by the facility, the primary constituents of concern in these 
wastewaters are hydrochloric acid and phosphorous acid, which are 
readily controlled via neutralization. The management practices for 
these wastewaters minimize opportunities for the release of 
hydrochloric acid or phosphorous acid to the environment in an 
undiluted or unneutralized state. Table III-23 summarizes our 
information on these wastewaters.

                       Table III-23.-- Wastewaters From Phosphorus Trichloride Production
----------------------------------------------------------------------------------------------------------------
                                      Number of                                                   Sequential
          Waste category              reported       1998 Volume     Reported hazard codes        management
                                     generators         (MT)                                      practices
----------------------------------------------------------------------------------------------------------------
Final washout water from reactor.               1    not reported  none....................  (1) pretreatment in
                                                                                              tanks,
                                                                                             (2) POTW.
Caustic scrubber water...........               3       4,236 \1\   none...................  (1) pretreatment in
                                                                                              tanks,
                                                                                             (2) POTW or NPDES.
Process scrubber water...........               3      12,528 \1\  D002 (one facility).....  (1) pretreatment or
                                                                                              neutralized in
                                                                                              tanks,
                                                                                             (2) POTW or NPDES.
----------------------------------------------------------------------------------------------------------------
\1\ Volumes from 1996 or 1997 are included in the totals when the wastes were not generated by a facility in
  1998.

    We have assessed the management practices employed for these wastes 
and determined that no exposure pathway of concern exists that warrants 
listing. We have determined that plausible management would be 
continued management in existing tank-based treatment systems. We 
believe the manufacturers have made a

[[Page 55732]]

considerable investment in wastewater treatment systems using tanks and 
will continue to use them. Further, we assumed that wastewater 
treatment tanks retain sufficient structural integrity to prevent 
wastewater releases to the subsurface (and therefore to groundwater), 
and that overflow and spill controls prevent significant wastewater 
releases. Thus, based on the lack of any significant likelihood of 
release of the constituents to groundwater, we did not project 
significant risks to groundwater from these wastes in the tank-based 
wastewater treatment scenario. Furthermore, discharges to POTWs and 
surface waters under NPDES are regulated under the Clean Water Act and 
are exempt from RCRA Subtitle C regulation and thus were not assessed.
    We also considered the possibility of air releases from tanks. For 
most wastes, the constituents of concern are nonvolatile metals, making 
volatilization a very unlikely pathway of release from tanks. In 
addition, the facilities have installed tank covers, further reducing 
the likelihood of release to the air. As a result, we did not model 
releases to air from tanks from the production of phosphorus 
trichloride. Thus, we propose not to list these wastewaters as 
hazardous wastes under RCRA.
    (3) Non-characteristic non-wastewaters. The phosphorus trichloride 
sector reported two waste categories that do not routinely exhibit any 
characteristic and that are often managed in Subtitle D landfills; 
these wastes are summarized in Table III-24.

                                 Table III-24.--Non-Characteristic Solid Wastes
----------------------------------------------------------------------------------------------------------------
                                      Number of
          Waste category              reported       1998 Volume     Reported hazard codes        Management
                                     generators         (MT)                                      practices
----------------------------------------------------------------------------------------------------------------
Spent filters for product........               1             0.1  none....................  industrial Subtitle
                                                                                              D landfill.
Wastewater treatment sludges.....               4       \1\ 1,100  none \2\................  Subtitle D landfill
                                                                                              or Subtitle C
                                                                                              landfill.
----------------------------------------------------------------------------------------------------------------
\1\ Volumes from 1997 are included in the totals when the wastes were not generated by a facility in 1998.
\2\ One facility reported that this wastewater treatment sludge is occasionally characteristically hazardous for
  D028 (dichloroethane), and the waste is then sent to a Subtitle C landfill. The dichloroethane is used in a
  process unrelated to the phosphorus trichloride process of interest in today's proposal.

    The phosphorus trichloride product is filtered to remove 
PCl4 and PCl5. These compounds produce a slime on 
the product and are more viscous than the product. The facility washes 
the filters before sending them to disposal. The contaminants are 
easily washed off because of their ready solubility in water. The spent 
filters are generated in very small volumes. We are proposing not to 
list them because we do not expect the washed filters to contain 
significant levels of contaminants of concern.
    All four of the facilities that generate wastewater treatment 
sludges commingle wastewaters from PCl3 production with 
wastewaters from other processes. The wastewater contribution from the 
phosphorus trichloride process is very small compared to volumes of 
wastewaters from the other processes. Therefore, the phosphorus 
trichloride process does not contribute significant amounts of 
constituents to this sludge.
    We do not believe any of these materials warrant listing as 
hazardous wastes from the production of phosphorus trichloride. 
Therefore, we propose not to list these wastes as hazardous wastes 
under RCRA in this rulemaking.
10. Potassium Dichromate
    a. Summary. We evaluated the wastes from the production of 
potassium dichromate and propose not to list any wastes from this 
process as hazardous wastes under RCRA. These wastes do not meet the 
criteria set out at 40 CFR 261.11(a)(3) for listing as hazardous. They 
do not pose a substantial present or potential hazard to human health 
or the environment.
    b. Description of the potassium dichromate industry. Potassium 
dichromate, which has a wide variety of industrial uses, was produced 
by a single facility in the United States in 1998. The U.S. demand for 
this chemical is very limited and has mostly been replaced by sodium 
dichromate for industrial use. Any demand not met by the U.S. facility 
is met by imports to U.S. distributors. Potassium dichromate is 
produced by reacting chromium trioxide with potassium hydroxide. The 
reactants are mixed in a reactor along with a crystal modifier. The 
potassium dichromate is crystallized, sent through a centrifuge to 
remove any remaining mother liquor, dried and packaged for sale. The 
single waste is filtered out from the mother liquor. The mother liquor 
is recycled back into the process.
    c. What kinds of wastes are generated by this process? There is one 
waste category generated from this process: filter solids and spent 
filter media. According to data submitted by the facility, this waste 
typically contains 12.5 percent chromium. The facility reports the 
waste as hazardous for chromium and manages it as hazardous (D007). The 
reported waste volume for 1998 was 0.6 MT. The waste is stored on-site 
in drums and is shipped off-site to a commercial Subtitle C facility 
for stabilization to meet the land disposal restrictions (40 CFR 268.40 
and 268.48) and final disposal in a Subtitle C landfill. Because the 
total chromium levels are so high, we believe this waste will always 
exhibit the toxicity characteristic.
    d. Agency evaluation. We propose not to list this waste as 
hazardous under Subtitle C of RCRA. This waste is currently managed as 
hazardous from the point of generation through ultimate disposal 
because it is characteristically hazardous. The composition of the 
waste is such that it is likely to always be characteristic for 
chromium. The rules applying to characteristic wastes adequately 
protect against mismanagement.
11. Sodium Chlorate
    a. Summary. We propose not to list any wastes from the production 
of sodium chlorate (NaClO3) as hazardous under Subtitle C of 
RCRA. Process sludges, spent filters, wastewaters and hydrogen gas are 
generated from the production of sodium chlorate. These wastes and 
materials are managed in a variety of ways. After analysis of the 
management practices and potential exposure pathways of these wastes 
and materials, we concluded that there are no risk pathways of concern. 
These wastes and materials do not meet the criteria set out at 40 CFR 
261.11(a)(3) for listing as hazardous. They do not pose a substantial 
present or potential hazard to human health or the environment.
    b. Description of the sodium chlorate industry. There were ten 
facilities producing sodium chlorate in 1999. This industry 
manufactures sodium chlorate crystals and solutions from electrolysis 
of a sodium chloride brine.

[[Page 55733]]

Sodium chlorate is the raw material used for the production of chlorine 
dioxide, which is replacing chlorine and sodium hypochlorite to be used 
as an oxidizing bleaching agent by the pulp and paper industry. The 
replacement of elemental chlorine with chlorine dioxide reduces 
effluent emissions of dioxin formed in the bleaching process of paper 
and pulp. Approximately ninety-eight percent of sodium chlorate is used 
to generate chlorine dioxide. The other important use of sodium 
chlorate is as an intermediate in the production of other chlorates, 
perchlorates, and chlorites.
    All ten facilities use a similar process in producing sodium 
chlorate. These facilities dissolve sodium chloride salt in water to 
create a liquid brine. The brine is treated to remove impurities, such 
as calcium carbonate and magnesium hydroxide. The treated brine is 
filtered and pumped into electrolytic cells. In the cells, sodium 
chloride is converted to chlorine and sodium hydroxide which further 
react to form sodium chlorate and hydrogen gas. This reaction is 
catalyzed by sodium dichromate. Sodium chlorate is then treated with 
heat and urea to remove residual sodium hypochlorite. Sodium chlorate 
is then processed further for crystallization, centrifuging, drying, 
and packaging. A more complete discussion of this process and the 
industry can be found in ``Sodium Chlorate Listing Background Document 
for the Inorganic Chemical Listing Determination'' in the docket for 
today's proposal.
    c. What kinds of wastes are generated by this process? Wastes 
generated from the production of sodium chlorate consist of process 
sludges, spent filters and wastewaters. Based on an evaluation of 
survey responses from the ten sodium chlorate producers, we divided the 
wastes further into six general waste categories based on the presence 
or absence of chromium and lead. The sodium chlorate industry in 
general characterizes wastes that have been in contact with chromium or 
lead as hazardous (D007 or D008). Chromium is introduced into the 
process by the addition of sodium dichromate into electrolytic cells to 
protect electrodes from corrosion and to improve product yields. The 
presence of lead in the wastes results from the deterioration of anodes 
that can be used in the electrolytic cells. The six waste categories 
are:

--Process sludges with chromium or lead. These include electrolytic 
cells sludge, product filter press sludge, and those brine treatment 
sludges generated from purification where brine is formed by mixing 
salts with chrome-laden wastewaters recycled from various steps of the 
process.
--Process sludges without chromium and lead. These wastes include 
filter press sludge or drum sludge from treatment of brine, when 
recycled chrome-laden wastewater is not used in the brine dissolution 
step.
--Spent filters with chromium or lead. The filters are generated at 
several points in the production process, but most are generated after 
the electrolysis of the brine solution when the mother liquor is 
filtered to remove impurities.
--Spent filters without chromium and lead. Examples include disposable 
cartridge and sock filters from treatment of brine, when recycled 
chrome-laden wastewater is not used in the brine dissolution step.
--Wastewaters with chromium that are not recycled back to the process.
--Other wastewaters that do not contain chromium or lead and are not 
recycled (condensate, cooling water, and ion-exchange wastewater).

    In addition to these wastes, other materials are produced by all 
ten facilities during the production of sodium chlorate that are piped 
directly back to the production process. Scrubber waters and filtrates 
are piped to on-site sodium chlorate production units for use. Because 
these materials are managed prior to reuse in ways that present low 
potential for releases to the environment, and because we evaluated 
process wastes generated after they are reused, we do not believe that 
these secondary materials present significant threats. At all ten 
facilities, hydrogen gas is produced by the electrolysis units and is 
either piped to on-site boilers, vented, or in one case, piped to a 
compression plant where it is compressed and sold. Because the material 
is a gas produced from a production unit rather than a waste management 
unit and is conveyed to its destination via piping, the gas is not a 
solid waste. RCRA Section 1004(27) excludes non-contained gases from 
the definition of solid waste and thus they cannot be considered a 
hazardous waste. (See 54 FR 50973) Because the gaseous materials are 
not solid wastes when produced, we did not evaluate them further for 
purposes of listing.
    One facility reports generating a wastewater (sulfate solution) 
from brine treatment. The wastewater is transported to an off-site 
facility and used in their black liquor pulping process. The sulfate 
solution is added to black liquor for use in a wood digester. The 
process in the digester is outside the scope of the consent decree and 
we have not evaluated risks from wastes that it produces. We note, 
however, that the reuse of black liquor is excluded from regulation (40 
CFR 261.4(a)(6)). The sulfate solution is stored in tanks prior to use 
in the pulping process, which minimizes the potential for releases.
How Are These Wastes Currently Being Managed?
    Table III-25 summarizes the six waste categories, waste 
characteristics, waste volumes, and their current management practices:

                              Table III-25.--Waste From Sodium Chlorate Production
----------------------------------------------------------------------------------------------------------------
                                                                        1998 Volume
  Waste category (number of facilities)    Reported Waste Codes \1\        (MT)          Management practices
----------------------------------------------------------------------------------------------------------------
Process sludges with chromium or lead     D001, D002, D007, D008....          28,547  Nine facilities store the
 (10).                                                                                 waste on site in
                                                                                       containers and then send
                                                                                       it to Subtitle C
                                                                                       landfills or
                                                                                       incinerators; one
                                                                                       facility decharacterizes
                                                                                       the waste in tanks before
                                                                                       managing it in on-site
                                                                                       surface impoundments. Two
                                                                                       facilities did not report
                                                                                       hazard codes.

[[Page 55734]]

 
Process sludges without chromium and      none reported.............           1,886  Three facilities store the
 lead (5 \2\).                                                                         waste on site in
                                                                                       containers and then send
                                                                                       it off-site to municipal
                                                                                       Subtitle D landfills; one
                                                                                       facility stores the waste
                                                                                       on a concrete pad with
                                                                                       secondary containment
                                                                                       before applying it to an
                                                                                       on-site land farm; one
                                                                                       facility stores the waste
                                                                                       on site in containers and
                                                                                       then sends it off-site to
                                                                                       an industrial Subtitle D
                                                                                       landfill; one facility
                                                                                       stores the waste on site
                                                                                       in containers before
                                                                                       sending it off-site for
                                                                                       recycling.
Spent filters with chromium or lead (7).  D001, D007, D008..........            82.9  All seven facilities
                                                                                       classify the waste as
                                                                                       hazardous; six send the
                                                                                       waste to Subtitle C
                                                                                       landfills or
                                                                                       incinerators; one
                                                                                       facility decharacterizes
                                                                                       the waste on-site in
                                                                                       tanks, stores it in a
                                                                                       closed compactor, then
                                                                                       ships the waste off-site
                                                                                       to an industrial Subtitle
                                                                                       D landfill.
Spent filters without chromium and lead   none reported.............            3.52  Three facilities store the
 (4).                                                                                  waste on site in
                                                                                       containers and send it
                                                                                       off-site to Subtitle D
                                                                                       landfills. One facility
                                                                                       stores the waste with
                                                                                       process sludge in on-site
                                                                                       containers and then sends
                                                                                       it off-site to a Subtitle
                                                                                       C facility for
                                                                                       stabilization prior to
                                                                                       disposal in a Subtitle C
                                                                                       landfill.
Wastewaters with chromium that are not    D002, D007................          26,736  One facility sends the
 recycled back to the process (2).                                                     wastewater to an off-site
                                                                                       Subtitle C facility for
                                                                                       treatment and disposal.
                                                                                       One facility combines and
                                                                                       treats the wastewater
                                                                                       with other process
                                                                                       wastewaters in tanks
                                                                                       prior to discharge to on-
                                                                                       site surface
                                                                                       impoundments.
Other wastewaters that do not contain     none reported.............      10,744 \3\  Discharged via NPDES
 chromium or lead and are not recycled                                                 permit or to a POTW.
 (condensate, cooling water, ion-
 exchange wastewater).
----------------------------------------------------------------------------------------------------------------
\1\ D001 (ignitability); D002 (corrosivity); D007 (chromium); D008 (lead).
\2\ One facility contributes more than one residuals to this waste group.
\3\ Two facilities did not report volumes of this wastewater.

    d. Agency evaluation. We selected wastes from three facilities for 
sampling. As described in detail in ``Sodium Chlorate Listing 
Background Document for the Inorganic Chemical Listing Determination'' 
in the docket for today's proposal, we selected these facilities and 
wastes because based on the survey information collected, we believe 
that the wastes generated by these three facilities are fully 
representative of the wastes generated by this industry and their 
management practices.
    We evaluated the characteristics and current management practices 
of each of the six waste categories. The details of our evaluation 
follow.
    (1) Process sludge with chromium or lead.
How Is This Waste Managed?
    The predominant source of process sludge with chromium or lead is 
from the periodic cleanout of electrolytic cells used to convert the 
brine solution to sodium chlorate. All ten facilities generate this 
waste. Seven facilities classify their wastes as characteristic and 
send it off-site to Subtitle C landfills or incinerators. Two 
facilities do not classify their wastes as characteristic but 
nevertheless send their wastes to Subtitle C landfills.
    The tenth facility, located in Hamilton, Mississippi, reports this 
waste to be characteristic and treats it in tanks to reduce hexavalent 
chromium to the relatively stable trivalent state. The facility 
commingles this sludge with wastes from the production of titanium 
dioxide (TiO2) in these tanks. The treated mixture is 
subsequently managed in a series of four surface impoundments, three of 
which are lined with leachate collection systems. Today's proposal 
separately addresses the titanium dioxide wastes that are commingled 
with this sodium chlorate sludge (see section III.F.14.c.(14)).
How Was This Waste Characterized?
    We collected a total of six samples to assess this waste 
categories. Three samples of the sludge from electrolytic cells were 
collected at two facilities where the wastes were destined for Subtitle 
C treatment and disposal. These two facilities generate and manage this 
waste as characteristically hazardous. These samples were part of the 
record characterizing this waste category, but were not used for risk 
assessment.
    We collected another three samples from the Hamilton, Mississippi 
facility that classifies this waste as characteristically hazardous and 
treats it in tanks to remove the characteristic prior to pumping the 
effluent to on-site surface impoundments. One sample (KM-SC-01) 
reflects the untreated sodium chlorate sludge collected from a 
dedicated sump prior to commingling with the titanium dioxide 
wastewaters. The second sample (KM-SI-01) is the treated combined 
wastes collected at the inlet to the surface impoundments. The

[[Page 55735]]

third sample (KM-SI-04) is the treated commingled sludge collected from 
one of the on-site surface impoundments.
    Table III-26, below, represents the analytical results for the 
Hamilton, Mississippi samples for total and hexavalent chromium, the 
primary constituent of concern. Total constituent analyses were 
conducted for the untreated waste. No other toxicants in the untreated 
wastewater sample (KM-SC-01) exceed the health-based levels. For the 
treated waste and the sludge collected from the impoundment, total and 
leaching analyses were conducted to allow us to assess potential 
releases to the environment. Our analytical data shows that total 
hexavalent chromium level in the treated sample (KM-SI-01) is below the 
HBL for hexavalent chromium, demonstrating the effectiveness of the 
treatment process. We assessed the treated commingled sludge settled in 
the impoundments and found that the chromium levels did not exceed the 
HBLs.

                               Table III-26.--Analytical Data for Sodium Chlorate
----------------------------------------------------------------------------------------------------------------
                                      KM-SC-01      KM-SI-01  (Treated        KM-SI-04  (Treated
                                     (Untreated    commingled NaC1O3 and     commingled NaC1O3 and
                                       NaC1O3          TiO2 wastes)             TiO2 sludge in
                                       wastes   --------------------------       impoundment)
      Constituents of concern          only)                              --------------------------     HBL
                                   ------------- Total  (mg/   SPLP  (mg/
                                    Total  (mg/      kg)           l)      Total  (mg/   SPLP  (mg/
                                         1)                                    kg)           l)
----------------------------------------------------------------------------------------------------------------
Chromium..........................         0.99         31.1         0.05        1,140         0.05           23
Hexavalent Chromium...............       0.85 L         0.02         0.02          0.8         0.03        0.05
----------------------------------------------------------------------------------------------------------------
L: Concentration reported from analysis performed outside method recommended holding time. Value should be
  considered biased low.

    The total chromium concentration in the treated waste is higher 
than the untreated waste due to commingling with other wastes from the 
titanium dioxide production process. There are other constituents 
detected in the treated commingled waste sample (KM-SI-01) that are 
attributable to the titanium dioxide production process; these 
constituents are assessed in section III.F.14.c.(14) of today's 
proposal.
What Is EPA's Listing Rationale for This Waste?
    We propose not to list this waste category. Seven facilities 
consider wastes in this category to be characteristically hazardous 
(for D001, D002, D007 or D008) and manage the wastes under Subtitle C 
regulations. We believe that these regulations adequately protect 
against mismanagement. Two facilities do not classify their wastes as 
characteristic but send them to Subtitle C landfills. We also believe 
that this practice adequately prevents mismanagement. The remaining 
facility (which does not identify its sludges as characteristic 
hazardous wastes) treats the sludge in tanks to reduce hexavalent 
chromium to trivalent chromium prior to placement in on-site surface 
impoundments. We found that the waste did not pose risks during 
treatment because there are no exposure pathways of concern for the on-
site treatment tanks. The wastes are treated in concrete tanks with 
secondary containment which minimize potential releases to groundwater. 
We also are not concerned with potential air releases from these tanks 
as neither volatile contaminants nor airborne particulates are likely 
to be present in the wastes. As discussed above, the primary 
constituent of concern in this waste is hexavalent chromium, which is 
treated to form relatively stable trivalent chromium. The physical form 
of the wastes (i.e., sludge with high water content) eliminates the 
potential for a significant release of airborne particulates. 
Furthermore, our analytical data show that the waste, after treatment, 
does not contain any constituents of concern at levels exceeding 
health-based levels.
    (2) Process sludge without chromium and lead.
How Is This Waste Managed?
    This sludge is produced as part of the initial purification of the 
brine solution. Five facilities report generating this type of waste 
and managing it as nonhazardous. Four facilities manage the waste in an 
on-site land farm, off-site municipal Subtitle D landfills, and an 
industrial Subtitle D landfill. One facility ships their waste off-site 
for recycling.
    We collected a total of four samples of this waste category from 
two facilities. Two of the four samples (HT-SN-01 and EC-SN-03) are 
representative of wastes that are land disposed. The other two samples 
(EC-SN-01 and EC-SN-02) are representative of wastes that are generally 
recycled and occasionally also landfilled. Table III-27 identifies the 
constituents of concern that we found to be present in the waste at 
levels exceeding their respective HBLs and/or soil screening levels.

                                               Table III-27.--Analytical Results for Sodium Chlorate Process Sludge Without Chromium and Lead (ppm)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                HT-SN-01                      EC-SN-03                      EC-SN-01                      EC-SN-02
                      Parameter                      ------------------------------------------------------------------------------------------------------------------------    HBL     \1\SSL
                                                        Total     TCLP      SPLP      Total     TCLP      SPLP      Total     TCLP      SPLP      Total     TCLP      SPLP
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Arsenic.............................................      14.3   \2\0.03      0.05         5     0.005      0.05         5     0.005      0.05         5     0.005      0.05    0.0007       5.2
Cadmium.............................................      27.4      0.05      0.05         5      0.05      0.05         5      0.05      0.05         5      0.05      0.05    0.0078       4.3
Chromium............................................      57.3      0.05      0.05      15.3      0.05      0.05         5      0.05      0.05      10.1      0.05      0.05        23        37
Copper..............................................      17.2      0.25      0.05      15.3      0.05      0.05         5      0.25      0.05       5.3      0.25      0.05       1.3        17
Lead................................................      14.8     0.024      0.03       139      0.03      0.03      19.3    0.12 E     0.001      34.9    0.05 E   0.002 E     0.015      400*
Manganese...........................................      69.2      0.08      0.05       238       4.5      0.05       125       0.5      0.05      51.9       0.7      0.05      0.73       330
Mercury.............................................     0.5 L     0.002    0.0002       0.1     0.002    0.0002       0.1     0.002    0.0002       0.1     0.002    0.0002    0.0047       24*
Nickel..............................................       7.4       0.2      0.05      12.1       0.4      0.05         5       0.2      0.05         5       0.2      0.05      0.31        13
Silver..............................................       1.1       0.1      0.01         1       0.1      0.01         1       0.1      0.01         1       0.1      0.01     0.078      400*
Zinc................................................       111         2       0.5       279      10.6       0.5        50         2       0.5        50         2       0.5       4.7       48
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ SSL: Soil Screening Level based on geometric mean background concentration (mg/kg) in soils in conterminous U.S. or soil ingestion HBL (marked *).
\2\ Results are less than the typical laboratory reporting limit, but are greater than the calculated instrument detection limit.
E: Analysis performed outside recommended holding time. Reported value should be considered as estimated.


[[Page 55736]]

What Management Scenarios Did We Aassess?
    We evaluated wastes managed under the four identified management 
scenarios: on-site land farm, municipal Subtitle D landfill, industrial 
Subtitle D landfill, and recycling.
    Land farm scenario. One facility reports managing 37 MT/year of 
this waste in an on-site permitted land farm. EPA previously assessed 
this same land farm as part of the chlorinated aliphatics listing 
determinations (see proposed rule at 64 FR 46475, August 25, 1999). 
Today's assessment of sodium chlorate waste placed in the same unit is 
based on our earlier modeling of this unit for a waste from the 
production of chlorinated aliphatics (EDC/VCM sludges).
    In assessing this management scenario, we first compared the total 
constituent concentrations of all four record samples to background 
soil concentrations. The following metals exceeded this screening 
criteria: arsenic, cadmium, chromium, copper, lead, mercury, silver, 
and zinc. We then used the metal modeling results generated from the 
chlorinated aliphatics listing determination to calculate the 
proportional sodium chlorate risk. The calculated modeling results of 
arsenic, cadmium, hexavalent chromium, and zinc for the same land farm 
are all below a hazard quotient (HQ) of 1 and 10-6 risk 
thresholds for the land treatment scenario. Finally, we compared the 
total concentrations of copper, lead, mercury, and silver of all 
samples to the soil ingestion HBL because these constituents were not 
assessed in the chlorinated aliphatics risk analyses. The maximum total 
concentrations of lead, mercury, and silver are well below the soil 
ingestion HBL, and the maximum total concentration of copper in this 
waste (i.e., 17.2 mg/kg) is very close to the soil ingestion HBL (i.e., 
17 mg/kg). We believe that after mixing with soil in the land 
application unit, the copper concentration in the unit will be even 
lower. We do not believe this waste poses risk via volatilization to 
the air pathway because it does not contain any significant toxic 
volatile chemicals. In addition, the comparison described above for 
this unit, where we determined that the detected waste constituents are 
present in the waste at levels below or very close to the soil 
ingestion levels, suggests that any wind blown dust from the unit 
should not pose risk at levels of concern.
    Based on our analysis, we conclude that the waste does not present 
a substantial risk to human health or the environment when land 
applied.
    Landfill scenarios. Three facilities manage their wastes in 
municipal Subtitle D landfills and one facility manages its waste in an 
industrial Subtitle D landfill.
    We used the SPLP results of all four relevant samples to evaluate 
the industrial Subtitle D landfill management scenario. We found that 
the waste poses no substantial present or potential hazard to human 
health and the environment when managed in an industrial Subtitle D 
landfill because the SPLP leachate concentration of all constituents of 
the four samples of this waste category are below their respective 
HBLs.
    We used the TCLP results of all four relevant samples to assess the 
municipal Subtitle D landfill scenario. We modeled all three volumes 
reported being sent to municipal Subtitle D landfills. We focused our 
assessment on the geological regions in the northwestern and 
southeastern areas of the country because of the locations of the 
facilities and the landfills currently being used. The constituents we 
modeled are arsenic, lead, manganese, nickel, and zinc. The details 
regarding our modeling inputs and assumptions are provided in ``Sodium 
Chlorate Listing Background Document for the Inorganic Chemical Listing 
Determination'' and ``Risk Assessment for the Listing Determinations 
for Inorganic Chemical Manufacturing Wastes' in the docket for today's 
proposal. The results of our risk assessment are summarized below in 
Table III-28.

                         Table III-28.--Groundwater Pathway Risk Assessment Results for Process Sludge Without Chromium and Lead
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                           Arsenic                       Manganese                       Nickel                         Zinc
                              --------------------------------------------------------------------------------------------------------------------------
          Percentile            Adult cancer    Child cancer
                                    risk            risk          Adult HQ        Child HQ       Adult HQ       Child HQ       Adult HQ       Child HQ
--------------------------------------------------------------------------------------------------------------------------------------------------------
90th.........................  3E-08.........  2E-08.........  2E-04.........  4E-04........  2E-06........  3E-06........  5E-08........  1E-07
95th.........................  2E-07.........  2E-07.........  6E-04.........  1E-03........  2E-05........  3E-05........  5E-06........  1E-05
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Based on these risk assessment results, we conclude that process 
sludge without chromium and lead does not pose a substantial present or 
potential hazard to human health and the environment when managed in 
municipal Subtitle D landfills. We calculated hazard quotients for non-
carcinogenic compounds (lead, manganese, nickel, and zinc), and all of 
these were well below a value of one. We found no adult or child cancer 
risk for arsenic in excess of 1E-06 at the 95th percentile. Based on 
these results we conclude that this waste does not pose risk to human 
health and the environment. For a more complete description of this 
analysis, see ``Risk Assessment for the Listing Determinations for 
Inorganic Chemical Manufacturing Wastes'' in the docket for this 
proposal.
    Recycling scenario.--One facility ships their wastes to an off-site 
facility for reuse. The material is added to mined gypsum used to 
retard the setting of concrete. We assessed this use because it 
involves land placement, with higher likelihood of releases to the 
environment. Two samples of this waste category were collected from the 
facility that produces and manages this waste in such a fashion. We 
compared this use to a less protective landfarming scenario, which we 
modeled, and found no risk of concern. The volume of the waste is quite 
small (1%) when compared to the volume of mined gypsum used by the off-
site facility. We believe that the constituent concentrations in the 
final cement product would be even lower due to mixing with other 
materials.
What Is EPA's Listing Rationale For This Waste?
    Based on our assessments of the four management scenarios (on-site 
land farm, municipal Subtitle D landfill, industrial Subtitle D 
landfill, and recycling), we found that the wastes do not present a 
substantial risk to human health or the environment. Therefore, we 
propose not to list these wastes.
    (3) Spent filters with chromium or lead.

[[Page 55737]]

How Is This Waste Managed?
    Spent filters are generated at several points in the production 
process but most are generated after the electrolysis of the brine 
solution. Seven facilities report generating this waste. Six of the 
seven facilities report this waste to be characteristic and ship it to 
off-site Subtitle C landfills or incinerators. The seventh facility 
generates a very small volume of D007 waste that is acid-washed and 
decharacterized (to meet UTS) before being landfilled at an off-site 
industrial Subtitle D landfill.
How Was This Waste Characterized?
    We collected one sample of the spent filter that was 
decharacterized prior to being sent to an industrial Subtitle D 
landfill. We did not sample any of the six facilities that already 
adequately managed the waste under Subtitle C regulations. Table III-29 
presents the analytical results for the total and leaching analyses of 
the decharacterized spent filter sample (KM-FB-01) for arsenic, lead, 
total chromium, and hexavalent chromium. Chromium and lead are the two 
primary constituents of concern in wastes of this category. The sample 
was not collected from the facility that uses anodes with lead coating, 
thus lead was not present in this sample. Arsenic was the only 
constituent detected in the SPLP analysis of this sample at levels 
exceeding the HBL.

                  Table III-29.--Analytical Results for Spent Filters With Chromium (KM-FB-01)
----------------------------------------------------------------------------------------------------------------
                                                                                                  Drinking water
                    Parameter                     Total  (mg/kg)   TCLP  (mg/l)    SPLP  (mg/l)     HBLs (mg/l)
----------------------------------------------------------------------------------------------------------------
Arsenic.........................................             0.5             0.5        \1\0.005          0.0007
Chromium........................................            41.0            0.05            0.05              20
Hexavalent Chromium.............................            16.8           \2\NA        \2\0.022            0.05
Lead............................................               5             0.5            0.03          0.015
----------------------------------------------------------------------------------------------------------------
\1\ Results are less than the typical laboratory reporting limit, but are greater than the calculated instrument
  detection.
\2\ NA Not applicable. Typical TCLP leaching solution is not suitable for leachable hexavalent chromium because
  most (or all) hexavalent chromium in TCLP waste leachates were converted to trivalent chromium. The leach test
  for hexavalent chromium was modified by replacing the typical (TCLP/SPLP) solution with deionized water.

What Is EPA's Listing Rationale For This Waste?
    As previously noted, six of the seven generators of this waste 
report managing their wastes in Subtitle C facilities as 
characteristically hazardous from the point of generation through 
ultimate disposal. We did not conduct risk assessment on wastes 
identified as hazardous wastes and managed in Subtitle C facilities 
because listing would not provide any significant incremental control 
of wastes already managed under Subtitle C. We evaluated the small 
volume waste (i.e., 2.3 MT/yr) generated by the seventh facility that 
decharacterizes its waste before landfilling in an industrial Subtitle 
D landfill.
    Because the volume of this waste is relatively small, we used a 
screening analysis (described in section III.E.3) to screen the 
potential risk to groundwater associated with landfilling this waste. 
We found that the SPLP data for arsenic screens out because the volume 
of the waste generated by the facility is insufficient to release 
arsenic at levels of concern. For a more complete description of this 
analysis, see ``Risk Assessment for the Listing Determinations for 
Inorganic Chemical Manufacturing Wastes'' in the docket for this 
proposal.
    Our analytical data demonstrate that the waste is effectively 
decharacterized and does not pose risks warranting listing for 
chromium, the primary constituent of concern in this waste. The result 
of the screening analysis for arsenic, the only constituent present in 
the waste's leachate at levels exceeding the HBL, shows that the 
arsenic in this waste does not pose risk to human health and the 
environment. Therefore, we propose not to list spent filters with 
chromium.
    (4) Spent filters without chromium and lead.
How Is This Waste Managed?
    This residual is usually generated as part of the initial brine 
purification steps, where impurities are removed from the brine 
solution, and from filtering of product during packaging. Four 
facilities report generating this type of waste. Two of these four 
facilities manage their wastes as nonhazardous in municipal Subtitle D 
landfills. One facility manages its waste as nonhazardous in an 
industrial Subtitle D landfill. One facility sends their spent filters 
along with process sludge off-site to a Subtitle C facility for 
stabilization prior to disposal in a Subtitle C landfill. These wastes 
are generated in very small volumes.

How Was This Waste Characterized?

    We collected two samples (HT-FB-01 and HT-FB-02) from one facility. 
These two samples are representative of wastes in this category that 
are land disposed. We found that antimony, arsenic, boron, hexavalent 
chromium, and lead in the TCLP or SPLP waste leachates exceeded their 
HBLs. We also found that cadmium was not detected in the leachates at a 
detection level of six times higher than its HBL. The detection limit 
was high due to dilution to minimize sample matrix interferences. 
Information on constituents of concern is summarized in Table III-30.

                                      Table III-30.--Analytical Results for Spent Filters Without Chromium or Lead
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                             HT-FB-01                                        HT-FB-02
                Parameter                ------------------------------------------------------------------------------------------------   HBL  (mg/l)
                                          Total  (mg/kg)   TCLP  (mg/l)    SPLP  (mg/l)   Total  (mg/kg)   TCLP  (mg/l)    SPLP  (mg/l)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Antimony................................            34.1           0.018           0.005               5           0.012           0.005           0.006
Arsenic.................................             7.3           0.014           0.003             5.3           0.005           0.005          0.0007
Boron...................................              50             6.1            0.05              50            0.67             0.5             1.4
Cadmium.................................            22.5            0.05            0.05               5            0.05            0.05           0.008
Cr, +6..................................             0.8              NA            0.02           2.8 L              NA          0.19 L            0.05

[[Page 55738]]

 
Lead....................................             8.7           0.024            0.06             7.1           0.020           0.012          0.015
--------------------------------------------------------------------------------------------------------------------------------------------------------
L: Concentration reported from analysis performed outside required holding time. Value should be considered biased low.

What Management Scenarios Were Assessed?
    We modeled both the industrial (0.6 MT/year) and municipal (2.8 MT/
year) landfill scenarios, based on the reported management practices.
    We used the SPLP leachate concentrations to evaluate the industrial 
landfill scenario. The constituents of concern that exceeded their 
respective HBLs in the SPLP results were arsenic, hexavalent chromium, 
and lead. We evaluated these constituents using the de minimis volume 
screening analysis, as described in section III.E.3 of today's 
proposal. The analysis suggests that hexavalent chromium and lead are 
not of concern. We then modeled arsenic using our standard groundwater 
model for the industrial landfill scenario.
    We used the TCLP leachate concentrations to evaluate the municipal 
landfill scenario. Using the de minimis volume analysis, we screened 
out boron, hexavalent chromium, and lead. We then conducted full 
groundwater modeling for the municipal scenario for antimony, arsenic, 
and cadmium.
What Are the Results of EPA's Risk Assessment for This Waste When 
Managed in an Industrial Subtitle D Landfill?
    Our risk assessment results for the industrial landfill scenario, 
summarized below in Table III-31, suggest that the only constituent of 
concern that required modeling (arsenic) does not pose a substantial 
present or potential hazard to human health and the environment. We 
found no arsenic cancer risk in excess of 1E-08 at the 95th percentile 
for either adult or child exposure scenarios. Therefore, we believe 
that this waste when managed in industrial Subtitle D landfills clearly 
does not warrant listing. For a more complete description of this 
analysis, see ``Risk Assessment for the Listing Determinations for 
Inorganic Chemical Manufacturing Wastes'' in the docket for this 
proposal.

   Table III-31.--Risk Results for Filters Without Chromium and Lead--
                 Industrial Subtitle D Landfill Scenario
------------------------------------------------------------------------
                                                  Arsenic
            Percentile            --------------------------------------
                                    Adult cancer risk  Child cancer risk
------------------------------------------------------------------------
90th.............................  1E-09               8E-10
95th.............................  5E-09               4E-09
------------------------------------------------------------------------

What Are the Results of EPA's Risk Assessment for This Waste When 
Managed in Municipal Subtitle D Landfills?
    Our risk assessment results for the municipal landfill scenario, 
summarized below in Table III-32, suggest that the three constituents 
of concern (antimony, arsenic, and cadmium) do not pose a substantial 
present or potential hazard to human health and the environment. The 
hazard quotients, for both the adult and child exposure scenarios, of 
antimony are less than 0.01 at the 95th percentile, and of cadmium, are 
less than 0.001 at the 95th percentile. We found no arsenic cancer risk 
in excess of 1E-08 at the 95th percentile for either adult or child 
exposure scenarios. Therefore, we believe that this waste when managed 
in municipal Subtitle D landfills does not warrant listing. For a more 
complete description of this analysis, see ``Risk Assessment for the 
Listing Determinations for Inorganic Chemical Manufacturing Wastes'' in 
the docket for this proposal.

                         Table III-32. Risk Results for Filters Without Chromium and Lead Municipal Subtitle D Landfill Scenario
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                  Antimony                                 Arsenic                                Cadmium
            Percentile            ----------------------------------------------------------------------------------------------------------------------
                                        Adult HQ            Child HQ        Adult cancer risk   Child cancer risk       Adult HQ            Child HQ
--------------------------------------------------------------------------------------------------------------------------------------------------------
90th.............................  5E-04               1E-03               5E-10               4E-10               3E-05               6E-05
95th.............................  2E-03               4E-03               5E-09               4E-09               1E-04               3E-04
--------------------------------------------------------------------------------------------------------------------------------------------------------

    (5) Wastewaters with chromium that are not recycled back to the 
process.
How Is This Waste Managed and How Is It Characterized?
    Two facilities report generating this wastewater and characterize 
it as hazardous (D002 and D007). One facility generates 11 MT per year 
of this wastewater from its on-site laboratory testings of the 
electrolyte in the electrolytic cells, the excess caustic from the 
hydrogen purification step, and the wastewater from the production of 
sodium chlorate crystals. The facility stores the wastewater on-site in 
closed tanks before sending it off-site to a hazardous waste facility 
for treatment and disposal. The other facility generates 26,725 MT per 
year of this wastewater from acid washing filters and anodes to remove 
buildup of trace metals on the surface. The facility combines the 
wastewaters with the wastewaters from its titanium dioxide production 
process and treats the commingled wastewaters in tanks. The treated 
wastewater is then discharged to on-site surface impoundments.

[[Page 55739]]

What Is EPA's Listing Rationale for This Waste?
    One facility identifies the waste as hazardous and manages it in 
accordance with Subtitle C regulations. We believe that applicable 
Subtitle C regulations adequately protect against mismanagement, and we 
did not investigate it further.
    For the other facility, in Hamilton, Mississippi, we evaluated its 
combined wastewaters and solids as described above in the ``process 
sludges with chromium or lead'' category. Today's proposal separately 
addresses the titanium dioxide wastes that are commingled with this 
sodium chlorate waste. We propose not to list these wastes.
    (6) Other wastewaters that do not contain chromium or lead and are 
not recycled.
How Is This Waste Managed?
    There are other wastewaters generated from several points of the 
process, including process condensate, cooling waters, and ion-exchange 
wastewater. Four facilities reported generating these wastewaters. Two 
facilities generate process condensates from condensing water vapor 
from their crystalizers, steam jets, or pad water evaporator. Both 
facilities store their process condensates in closed tanks. One 
facility neutralizes the condensate prior to discharging it to an NPDES 
permitted outfall. The other facility does not treat the condensate, 
but tests to ensure it meets its State Pollutant Discharge Elimination 
System permit prior to discharge to a river. One facility generates 
wastewater from regeneration of the ion-exchange unit that is used for 
purification of the brine. The wastewater is collected in a tank for pH 
neutralization before it is discharged to a POTW. One facility 
generates wastewater from cooling tower blowdown, chemical storage tank 
scrubber pad, hydrogen scrubber pad, and water demineralization area. 
These wastewaters are piped to its on-site NPDES facility to be 
processed and discharged.
What Is EPA's Listing Rationale for This Waste?
    We propose not to list these wastewaters as hazardous. We evaluated 
these wastewaters that are stored and treated in tanks or in a NPDES 
permitted facility. We found that these wastewaters do not pose risks 
warranting regulation during treatment because there are no exposure 
pathways of concern. The wastewater treatment tanks and the wastewater 
treatment facility provide sufficient structural integrity and have 
secondary containment areas to minimize potential releases to 
groundwater. We are unlikely to find potential air releases from these 
tanks or the permitted facility as neither volatile contaminants nor 
airborne particulates are likely to be present in these wastewaters.
12. Sodium Dichromate
    a. Summary. We have evaluated the wastes, waste management 
practices, and potential risk exposure pathways associated with the 
sodium dichromate production processes and propose not to list any 
wastes from this industry as hazardous wastes under Subtitle C of RCRA. 
These wastes do not meet the criteria listed under 40 CFR 261.11(a)(3) 
for listing a waste as hazardous. They do not pose a substantial 
present or potential threat to human health or the environment. We have 
identified no risks of concern associated with the current management 
of these wastes. Note that certain wastes from this sector are exempt 
mineral processing wastes which are not within the scope of today's 
listing proposal.
    b. Description of the sodium dichromate industry. Two facilities in 
the United States produce sodium dichromate; one in North Carolina and 
one in Texas. Both facilities sell their product on the open market in 
addition to using the material as a feedstock for various manufacturing 
processes on-site. The majority of sodium dichromate is used as a 
feedstock for the production of chromic acid. It is also used in a wide 
variety of other uses. For more detailed information concerning this 
industry, see ``Sodium Dichromate Listing Background Document for the 
Inorganic Chemical Listing Determination'' in the docket for today's 
proposal.
    The two sodium dichromate production facilities use somewhat 
different manufacturing processes and generate somewhat different 
wastes. Both facilities use imported chromite ore as their primary 
feedstock. They dry and grind the ore and feed it into a roasting kiln 
or hearth with other materials such as soda ash, lime, and sodium 
hydroxide. The facilities roast, then quench and leach the ore with 
water, producing sodium chromate solution and solid ore residues. Both 
facilities return the ore residues to the manufacturing process for 
further roasting and leaching. The facilities purify the resulting 
sodium chromate solution product stream by adjusting its pH, treating 
it with sodium carbonate, and, at the Texas facility, sodium 
dichromate, and filtering out the resulting solid impurities.
    The two facilities' processes diverge significantly at this point. 
At the Texas facility, the sodium chromate solution is either 
crystallized and sold or processed electrolytically to convert the 
sodium chromate to sodium dichromate. The electrolytic cell system also 
produces sodium hydroxide solution which, the facility reports, they 
sell. The North Carolina facility converts the sodium chromate solution 
to sodium dichromate through acidification, and the sodium dichromate 
is then partially evaporated. The acidification process also produces 
sodium sulfate and lower purity sodium sulfate ``saltcake,'' both of 
which the facility sells. The sodium dichromate is then either used in 
liquid form or further evaporated to produce a crystalline product.
    c. How does the Bevill Exclusion apply to wastes from the sodium 
dichromate manufacturing processes? The sodium dichromate manufacturing 
facilities produce two types of residuals which are eligible for the 
Bevill exemption once disposed: beneficiation wastes (See 40 CFR 
261.4(b)(7)(i)) and mineral processing wastes referred to as treated 
residue from roasting/leaching of chromium ore (see 40 CFR 
261.4(b)(7)(ii)(N)).
    Under the Bevill exemption, any wastes generated from beneficiation 
of ores, such as crushing, mixing, and milling, are Bevill exempt. Both 
facilities beneficiate ore by drying and grinding chromite ore and 
mixing the ore with other ingredients prior to placement in the 
roasting kiln and generate air pollution control dusts from these 
processes. However, the residuals from these processes, which would be 
Bevill exempt, are not disposed of but rather captured and returned to 
the process from which they originated for chromium recovery.
    In terms of when beneficiation stops and mineral processing starts, 
EPA determined in 1989 that the roasting/leaching of chromium ore to 
produce sodium chromate is mineral processing rather than 
beneficiation. 54 FR 36592 (September 1, 1989) stated:

    ``A specific exception to the above categorization system 
applies when the roasting/leaching sequence produces a final or 
intermediate product that does not undergo further beneficiation or 
processing steps (e.g., the leach liquor serves as an input to 
inorganic chemical manufacturing). In this type of situation, the 
Agency believes that the operation is most appropriately considered 
a processing, rather than a beneficiation, operation. In the context 
of this rulemaking, one candidate Bevill waste (roast/leach ore 
residue from primary chrome ore processing) is affected by this 
distinction; EPA believes that this material is clearly a waste from

[[Page 55740]]

processing, rather than beneficiation, of an ore or mineral.''

    The wastes generated after mineral processing begins are not Bevill 
exempt unless and until they become treated residue from the roasting/
leaching of chromium ore as specified in 40 CFR 261.4(b)(7)(ii)(N). The 
wastes eligible for the exclusion, once they are treated, are referred 
to later in this preamble and associated background documents as spent 
post-leach, spent post-neutralization ore residue, and waste heat 
boiler washout. These wastes are generated from roasting and leaching 
(including precipitation and filtration to remove the resulting 
impurities) of chromite ore. Both facilities generate these wastes, 
treat them in on-site treatment systems, and dispose of them in on-site 
surface impoundments. Note that in the January 23, 1990 Federal 
Register, EPA stated that the Bevill exemption applies to ``only those 
solids which are entrained in the slurry as it leaves the treatment 
facility and which settle out in disposal impoundments.''
    Wastes generated following the roasting/leaching processes to 
produce sodium chromate for sodium dichromate production are not Bevill 
exempt because they are not from the roasting/leaching of chromite ore. 
Wastes generated at these facilities that are not Bevill exempt include 
sodium chromate evaporation unit wastewaters (Texas facility), sodium 
dichromate evaporation unit wastewaters (Texas facility), caustic 
filter sludge (Texas facility), and salt cake drier scrubber wastewater 
(North Carolina facility).
    As described below, both facilities in the sodium dichromate 
manufacturing industry commingle wastes during the treatment process, 
ultimately producing a commingled treatment residue which is a mixture 
of Bevill exempt wastes and wastes which do not qualify for the Bevill 
exemption. In general, the majority of these mixtures consist of Bevill 
exempt wastes. Mixing Bevill exempt wastes with non-hazardous wastes 
does not affect the regulatory status of the Bevill wastes, but it also 
does not conversely extend Bevill exempt status to the non-hazardous 
wastes in the mixture (see 63 FR 28595). Therefore, in this rulemaking 
we have addressed that portion of the treatment residue mixture which 
derives from wastes which do not qualify for the Bevill exemption. In 
addition, in general, if any of the non-Bevill wastes exhibit a 
characteristic and is mixed with the Bevill wastes, the entire mixture 
may become subject to Subtitle C based on the Bevill mixture rule (See 
40 CFR 261.3(a)(2)).
    d. What kinds of wastes are generated by these processes? Table 
III-33 below briefly lists the facility-reported residuals from the 
sodium dichromate manufacturing industry, total industry residual 
volumes generated in 1998, RCRA hazard codes, and residual management 
practices.

                              Table III-33.--Sodium Dichromate Production Residuals
----------------------------------------------------------------------------------------------------------------
                                                                                          Sequential management
          Waste category               1998 volumes  (MT)       Reported waste codes            practices
----------------------------------------------------------------------------------------------------------------
                                             North Carolina Facility
----------------------------------------------------------------------------------------------------------------
Residuals commingled in spent ore
 residue treatment unit \1\:
    Spent post-neutralization ore  146,937..................  D007....................  Sent on-site to tank-
     residue (Bevill exempt after                                                        based spent ore residue
     treatment).                                                                         treatment unit with
                                                                                         NPDES permitted
                                                                                         discharge.
    Spent post-leach ore residue   25,930...................  D007....................  Sent on-site to tank-
     (Bevill exempt after                                                                based spent ore residue
     treatment).                                                                         treatment unit with
                                                                                         NPDES permitted
                                                                                         discharge.
    Saltcake drier scrubber        13,851...................  D007....................  Sent on-site to tank-
     wastewater.                                                                         based spent ore residue
                                                                                         treatment unit with
                                                                                         NPDES permitted
                                                                                         discharge.
    Waste heat boiler washout      70.......................  D007....................  Sent on-site to tank-
     (Bevill exempt after                                                                based spent ore residue
     treatment).                                                                         treatment unit with
                                                                                         NPDES permitted
                                                                                         discharge.
Residuals disposed of on-site:
    Reduced chromium treatment     129,503..................  None....................  Sent to on-site
     residues (commingled Bevill                                                         industrial Subtitle D
     exempt and non-exempt                                                               disposal unit.
     residues).
    Commingled treated             920,161..................  None....................  Passed through sand
     wastewaters (commingled                                                             filters then discharged
     Bevill exempt and non-exempt                                                        directly under NPDES
     residues).                                                                          permit or sent to on-
                                                                                         site industrial
                                                                                         Subtitle D disposal
                                                                                         unit.
Residuals disposed of off-site:
    Chromium-contaminated          67.......................  D007....................  Stored in on-site roll-
     filters, membranes, and                                                             off bin before off-site
     other plant waste.                                                                  treatment and landfill
                                                                                         disposal at Subtitle C
                                                                                         facility.
    Spent sand filter sands        21.7 (1997)..............  None....................  Stored in on-site drums
     (commingled Bevill exempt                                                           or roll-off bins before
     and non-exempt residues).                                                           disposal in off-site
                                                                                         industrial Subtitle D
                                                                                         landfill.
----------------------------------------------------------------------------------------------------------------
                                                 Texas Facility
----------------------------------------------------------------------------------------------------------------
Residuals commingled in spent ore
 residue treatment unit:
    Spent post-neutralization ore  60,000...................  D007....................  Sent to on-site,
     residue (Bevill exempt after                                                        covered, tank-based,
     treatment).                                                                         spent ore residue
                                                                                         treatment unit with
                                                                                         NPDES permitted
                                                                                         discharge.
    Caustic filter sludge........  80.......................  D002....................  Sent to on-site,
                                                                                         covered, tank-based,
                                                                                         spent ore residue
                                                                                         treatment unit with
                                                                                         NPDES permitted
                                                                                         discharge.
Residuals commingled in
 wastewater treatment unit \2\:
    Sodium dichromate evaporation   2,500.......  None....................  Sent to on-site, tank-
     unit wastewater.                                                                    based wastewater
                                                                                         treatment unit with
                                                                                         NPDES permitted
                                                                                         discharge.
    Sodium chromate evaporation    300..........  None....................  Sent to on-site, tank-
     unit wastewater.                                                                    based wastewater
                                                                                         treatment unit with
                                                                                         NPDES permitted
                                                                                         discharge.

[[Page 55741]]

 
Residuals disposed of on-site:
    Reduced chromium treatment     60,000...................  None....................  Sent to on-site
     residues from spent ore                                                             industrial Subtitle D,
     residue treatment unit                                                              double-lined surface
     (commingled Bevill exempt                                                           impoundment for
     and non-exempt residues).                                                           dewatering and
                                                                                         disposal. Impoundment
                                                                                         has NPDES permitted
                                                                                         outflow.
    Reduced chromium treatment     30,000 (1999)  None....................  Sent to on-site
     residues from wastewater                                                            industrial Subtitle D,
     treatment unit (commingled                                                          double-lined surface
     Bevill exempt and non-exempt                                                        impoundment for
     residues).                                                                          dewatering and
                                                                                         disposal. Impoundment
                                                                                         has NPDES permitted
                                                                                         outflow.
    Commingled treated             186,515..................  None....................  Sent to on-site
     wastewaters (commingled                                                             industrial Subtitle D
     Bevill exempt and non-exempt                                                        surface impoundment,
     residues).                                                                          filtered through sand
                                                                                         filters, then
                                                                                         discharged directly
                                                                                         under NPDES permit.
Residuals disposed of off-site:
    Process filters and            24.......................  D007....................  Stored in on-site roll-
     membranes, baghouse bags,                                                           off box before
     chromium-contaminated empty                                                         treatment and landfill
     containers, and other plant                                                         disposal at Subtitle C
     wastes.                                                                             facility.
    Spent sand filter sands        2 MT once      None....................  Placed in on-site non-
     (commingled Bevill exempt      every two years.                                     hazardous soil waste
     and non-exempt wastes).                                                             bin and then disposed
                                                                                         of in off-site
                                                                                         industrial Subtitle D
                                                                                         landfill.
----------------------------------------------------------------------------------------------------------------
\1\ Remediation well water, cooling tower blowdown, and stormwater are also treated in this unit. These
  materials are beyond the scope of this listing determination.
\2\ Stormwater and remediation well water are also treated in this unit. Contaminated media are not within the
  scope of this listing determination.

    In addition to these wastes, the sodium dichromate manufacturers 
produce residuals which are either piped back to the production process 
or sold for use in other manufacturing processes. Air pollution control 
devices capture materials that are returned to their units of origin or 
to other manufacturing process units. At the North Carolina facility, 
ore residue washwaters and calcium carbonate residuals are returned to 
the production process for chromium recovery. Chromium-bearing solution 
from the saltcake purification process is directly reused in the 
roasted ore quench, leach and filter process. At the Texas facility, 
chromium-containing residuals from scrubbers on the hearth and on the 
sodium chromate and dichromate evaporation/crystallization units are 
reused in the hearth kiln and quench tank units. Because these 
materials are reused in production units in ways that present low 
potential for release, and because we evaluated process wastes 
generated after the secondary material is reinserted into the process, 
we do not believe that these materials present significant risk.
    The North Carolina facility also produces for sale sodium sulfate 
``saltcake'' and purified sodium sulfate anhydrous from the sodium 
dichromate production process. The Texas facility sells hydroxide 
solution from their sodium dichromate production process. We found no 
information indicating that the facilities which purchase these 
materials burn them for energy recovery or incorporate them into 
products that are used on the land (use constituting disposal). Since 
these processes are outside the scope of the consent decree we did not 
evaluate any of these materials further. We did however, evaluate some 
residuals produced on-site at the North Carolina and Texas facilities 
during the preparation of the materials that are sold. See the 
discussions in the sections below of salt cake drier scrubber water and 
caustic filter sludge. Finally, the North Carolina facility produces 
some off-specification product, which it reinserts into the sodium 
dichromate manufacturing process. Off-specification product, when 
reinserted without reclamation into the process from where it 
originated, is not a solid waste. See the ``Sodium Dichromate Listing 
Background Document for the Inorganic Chemical Listing Determination'' 
for more details on these residuals.
    e. Waste characterization and Agency evaluation. Chromium is the 
primary constituent of concern in the wastes from both facilities. 
Chromium occurs in several production wastes at high levels, in some 
cases exceeding the TC level (5.0 mg/L) in TCLP leachate samples. These 
wastes are coded as hazardous (D007). Both facilities treat some of 
their D007 wastes on-site and send other D007 wastes off-site for 
treatment and disposal at permitted Subtitle C hazardous waste 
facilities. Various other wastes which fall below D007 regulatory 
levels are either treated on-site or sent off-site for disposal. No 
other constituents of concern were reported to be present in the wastes 
at levels of concern.
    We propose not to list any of the wastes from the sodium dichromate 
manufacturing industry. Many wastes from this industry are Bevill 
exempt once treated, and therefore not within the scope of the consent 
decree requirements. Other wastes are characteristically hazardous and 
are managed at permitted Subtitle C facilities off-site. Some wastes 
did not exhibit constituents at levels of concern for purposes of a 
listing given the nature of their management and disposal. The main 
constituent of concern, chromium, is treated on-site for many of the 
wastes.
    Several wastes from each of the facilities are disposed of in a 
treated form, rather than an as-generated form. In general, we focused 
our evaluation on the treated form of wastes because it is ultimately 
only the treated wastes which are disposed.
    The sections below describe how wastes are generated and managed at 
the two sodium dichromate manufacturing facilities, each with its own 
production process, and our rationale for proposing not to list the 
wastes. We solicit comments on the proposed listing decisions described 
below.
    (1) North Carolina Facility.
    (a) Residuals Commingled in Spent Ore Residue Treatment Unit. The 
North Carolina facility commingles and treats several characteristic 
wastes from sodium dichromate manufacturing in an on-site, tank-based 
treatment unit at the North Carolina facility. These four sodium 
dichromate manufacturing wastes are:

--Waste heat boiler washout, which are accumulated solids from the 
internal

[[Page 55742]]

components of the roasting kiln waste heat boilers (Bevill exempt after 
treatment)
--Spent post-leach ore residue (Bevill exempt after treatment)
--Spent post-neutralization ore residue (Bevill exempt after treatment)
--Saltcake drier scrubber wastewater

    We consider the saltcake drier scrubber wastewater to be a 
wastestream associated with the production of sodium sulfate at the 
North Carolina facility, rather than a sodium dichromate manufacturing 
waste. Nevertheless, we chose to exercise our discretion to evaluate 
the risk posed by the treated and untreated form of this residue. As 
explained below, we did not find risks warranting listing.
    All four wastes catalogued above go directly from their points of 
generation to the on-site spent ore residue treatment unit without 
intervening storage. The facility treats non-contact cooling tower 
blowdown, remediation well water, and stormwater in the treatment unit 
as well. The four manufacturing wastes comprise approximately 60-65% by 
volume of the wastes entering the treatment unit. The entire treatment 
process takes place in a series of tanks with secondary containment. 
Treatment consists of conversion of hexavalent chromium in the wastes 
to trivalent chromium with pickle liquor (ferrous chloride reducing 
agent). Trivalent chromium is a generally less toxic and less soluble 
form of chromium. Wastes containing a high percentage of solids (waste 
heat boiler washout, spent post-leach ore residue, and spent post-
neutralization ore residue) are also neutralized with lime slurry in 
order to increase precipitation of trivalent chromium compounds out of 
solution.
    The treatment sludge is then thickened in a series of clarifier 
tanks. Limestone is added to the thickened sludge to further stabilize 
chromium and other metals. All of the tanks in the treatment train have 
secondary containment and some are covered. Treated wastewaters, after 
passing through sand filters, discharge from the treatment unit under 
an NPDES permit or travel with the treated solid residues to the on-
site industrial Subtitle D disposal unit (see section 
III.F.12.e(1)(b)ii below regarding the commingled treated wastewaters).
    The Bevill exemption applies to the waste heat boiler washout, 
spent post-leach ore residue, and spent post-neutralization ore residue 
only after the wastes are treated. We evaluated the potential for 
releases from the treatment tanks. We assumed that the tanks were 
intact structures with minimal potential for releases to groundwater. 
We do not anticipate significant air releases because the wastes do not 
contain volatile constituents and have high moisture content. Also, 
some of the tanks have covers which further reduce the possibility of 
air releases. We are proposing not to list any of these four 
wastestreams undergoing treatment in this tank system.
    (b) Residuals Disposed of On-Site. (i) Commingled reduced chromium 
treatment residues. The reduced chromium sludge from the on-site spent 
ore residue treatment unit is slurried and conveyed directly from the 
treatment unit to one of two on-site industrial Subtitle D disposal 
units (former limestone quarries). Of the several treatment residues 
contributing to the final commingled treatment residue, only one falls 
within the scope of today's listing proposal; residue from treatment of 
saltcake drier scrubber wastewater (we believe this is not within scope 
of the consent decree but are evaluating it in this rule making). 
Residues from the treatment of waste heat boiler washout, spent post-
leach ore residue, and spent post-neutralization ore residue are Bevill 
exempt mineral processing wastes beyond the scope of today's listing 
proposal (see Section III.F.12(c)). Stormwater and remediation well 
water are contaminated media whose treatment residues we also consider 
to be beyond the scope of the consent decree (see section III.B of 
today's proposal). Therefore, we do not consider the risks posed by 
these treatment residues.
    According to information the facility submitted in their RCRA 
Section 3007 Survey response, the only potential constituent of concern 
in the untreated saltcake drier scrubber wastewater is chromium, 
detected at a level of 6 mg/L. Therefore, chromium is the only 
constituent we considered when assessing the level of risk from 
saltcake drier scrubber wastewater treatment residues.
    Of the total mass of chromium found in the commingled reduced 
chromium treatment residues, the saltcake drier scrubber wastewater 
contributes approximately 0.001%. This estimate is based on 
calculations using information the North Carolina facility provided to 
us on chromium contents and tonnages of waste exiting the spent ore 
residue treatment unit. Both the information and the calculations are 
further detailed in the ``Sodium Dichromate Listing Background Document 
for the Inorganic Chemical Listing Determination.''
    We found the treatment residues from saltcake drier scrubber 
solution to pose no significant risks to groundwater. After treatment 
for hexavalent chromium, the commingled reduced chromium treatment 
residues from 1998 showed weekly TCLP analysis levels of leachable 
chromium in the range of 0.01-1.00 mg/L for composite samples and 0.01-
0.76 mg/L for grab samples. Assuming that the saltcake drier scrubber 
wastewater's percent contribution to total chromium in the commingled 
residues is equal to its percent contribution to total chromium 
leaching from the commingled residues (0.001%), the saltcake scrubber 
solution was responsible for TCLP leaching levels of 
1 x 10-7 to 1 x 10-5 mg/L for composite samples 
and 3 x 10-7 to 2.28 x 10-5 mg/L for grab 
samples. The HBL for ingestion of hexavalent chromium is 0.047 mg/L and 
23 mg/L for trivalent chromium. The AWQC for hexavalent chromium is 
0.011 mg/L and 0.74 mg/L for trivalent chromium. Even at a maximum 
leaching level of 1 x 10-5 mg/L, the leachable chromium 
contribution of the saltcake drier scrubber wastewater indicates a very 
low level of risk to groundwater.
    The treated wastes are disposed in an uncovered disposal unit that 
resembles a surface impoundment. However, given the inorganic, 
nonvolatile nature of the treated wastes, we do not believe they pose a 
risk through airborne pathways. Given the low level of chromium 
leaching attributable to the one treatment residue within the scope of 
today's listing proposal and the lack of volatile constituents of 
concern, we propose not to list residues deriving from the treatment of 
saltcake drier scrubber wastewater.
    (ii) Commingled treated wastewaters. The spent ore residue 
treatment unit described in the sections above has clarifier units 
which discharge a wastewater stream to tank-based sand filters. After 
passing through sand filters, the treated wastewaters discharge through 
an NPDES-permitted outfall. These wastewaters are a mixture of non-
Bevill exempt and Bevill exempt treatment residues, and other treatment 
residues beyond the scope of the consent decree. The solids suspended 
in the wastewaters are a mixture of Bevill exempt and non-Bevill exempt 
treatment residues. The liquid portion, the majority of this 
wastestream, is a mixture of non-Bevill exempt residues, some of which 
are within the scope of this listing determination, and some of which 
derive from treatment of contaminated media and are therefore not with 
the scope of this listing determination. We did not find any

[[Page 55743]]

significant potential for releases from the tanks. (We assess spent 
filter media from the sand filters separately in section 
III.F.12.e(1)(c)ii below.) We concluded that the NPDES discharge is 
exempt from RCRA regulation.
    A portion of the commingled treated wastewaters remains with the 
commingled reduced chromium treatment residues discharged for disposal 
to the facility's on-site industrial Subtitle D disposal units. The 
facility also adds water to this mixture from either the nearby 
Northeast Cape Fear River or the quarry in order to help slurry and 
convey the residues to the disposal units.
    The liquids which separate from the settled treatment residues in 
the facility's disposal units are not Bevill exempt wastes (see Section 
III.F.12.c). Because these liquids derive from the same treatment unit 
from which the NPDES-discharged wastewaters discussed above derive, we 
are assuming their chemical composition is very similar to that of the 
wastewaters discharged under the facility's NPDES permit. We used NPDES 
permit discharge data, available to the public from the EPA's 
Envirofacts database, \42\ as a surrogate for characterization of this 
wastewater (see discussion of SPLP filtrate in Section III.E.3). The 
exposure pathway of concern is the groundwater underlying the 
facility's disposal units and consumption of the groundwater as 
drinking water.
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    \42\ http://www.epa.gov/enviro/index_java.html.
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    According to the North Carolina facility's NPDES permit, the 
facility is allowed to discharge 0.31 pounds per day of hexavalent 
chromium to the Northeast Cape Fear River. Given the amount of treated 
wastewater reported to be discharged in 1998 and using the permit 
loading as an upperbound value, we estimate that the facility produced 
an NPDES effluent with an average hexavalent chromium concentration of 
0.056 mg/L. This concentration is less than twice the HBL for 
hexavalent chromium (0.047 mg/L).\43\ However, according to NPDES 
compliance monitoring data for the facility, no hexavalent chromium was 
detected in the facility's NPDES effluent in 1998. Therefore, it is 
likely that the actual concentration of hexavalent chromium in the 
facility's commingled treated wastewaters is less than the 
concentration the facility is permitted to release.
---------------------------------------------------------------------------

    \43\ As described in Section III.E.3, we used engineering 
judgment to screen out constituents with concentrations within a 
factor of two of the HBL.
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    According to the North Carolina facility's NPDES permit, the 
facility is also permitted to discharge 2.72 pounds of combined 
hexavalent and trivalent chromium per day. Making the conservative 
assumption that all 2.72 pounds of chromium are trivalent chromium and 
given the amount of treated wastewater discharged in 1998, we estimated 
that the facility produced an NPDES effluent with an average chromium 
concentration of 0.49 mg/L, which is less than 23 mg/L, the HBL for 
trivalent chromium. Actual reported levels of total chromium release 
were well below the permit limit.
    Given that the levels of chromium present in the on-site disposal 
unit liquids are less than or within a factor of two of the HBLs, we do 
not believe they pose a risk to human health or the environment through 
groundwater underlying the disposal unit that supports listing these 
wastewaters as a hazardous waste.
    (c) Residuals Disposed of Off-Site. (i) Chromium-contaminated 
filters, membranes, and other plant wastes. This waste category from 
the North Carolina facility includes spent filters, membranes, and 
various other plant wastes which exceed the TC level for chromium. The 
wastes are stored in a closed roll-off bin on-site before being sent 
off-site to a permitted Subtitle C facility for treatment and disposal 
in a landfill. We feel that applicable Subtitle C regulations 
adequately prevent mismanagement and therefore propose not to list 
these wastes.
    (ii) Spent sand filter sands. The North Carolina facility generates 
waste sand material from the spent ore residue treatment unit sand 
filters which filter treated wastewaters prior to their NPDES-permitted 
discharge. The purpose of the sand filters is to remove any residual 
solids which the treatment unit clarifiers fail to remove upstream in 
the treatment process. Since the clarifiers capture the majority of the 
solids, the sand filters capture smaller amounts of treatment residue. 
The most recent disposal of sand from the filters took place in 1997. 
The facility stores the spent sand in closed drums or roll-off bins on-
site before disposing of them in an off-site industrial Subtitle D 
solid waste landfill.
    According to information submitted to EPA by the North Carolina 
facility, this residue does not exhibit any constituent above the TC 
level according to TCLP leachate analysis. The only detected 
constituent of potential concern was chromium, at a level of 0.2 mg/L. 
Residue from treatment of saltcake drier scrubber wastewater is the 
only residue contributing to the chromium levels in the spent sand 
filters which also falls within the scope of today's listing proposal. 
All other wastes are either Bevill exempt wastes or treatment residues 
from contaminated media or non-contact cooling water, none of which 
falls within the scope of the consent decree.
    As discussed in section III.F.12.e(1)(b), the saltcake drier 
scrubber solution contributes approximately 0.001% of the total 
chromium exiting the spent ore residue treatment unit. Assuming that a 
waste's percent contribution to total chromium exiting the treatment 
unit is equal to its percent contribution to total chromium leaching 
from waste exiting the unit, the figures above indicate a TCLP leaching 
level of 2 x 10-\6\ mg/L due to the contributions of the 
saltcake drier scrubber wastewater.
    The HBL for hexavalent chromium is 0.047 mg/L and 23 mg/L for 
trivalent chromium. The AWQC for hexavalent chromium is 0.011 mg/L and 
0.74 mg/L for trivalent chromium. At a level of 2 x 10-\6\ 
mg/L, the leachable chromium contribution of the saltcake drier 
scrubber wastewater presents a very low level of risk.
    The waste is inorganic in nature and therefore we do not expect it 
to contain volatile constituents of concern. In addition, the waste is 
stored before disposal in a closed container. We do not believe, 
therefore, that this waste poses a risk via airborne pathways. Given 
the low level of risk posed by the saltcake drier scrubber wastewater 
treatment residue contribution to leachable chromium levels in the 
spent sand filters and its nonvolatile nature, we propose not to list 
this waste.
    (2) Texas Facility. (a) Residuals Commingled in On-Site Treatment 
Units. At the Texas facility, commingling and treatment of four 
untreated wastes takes place in two different on-site, tank-based 
treatment units. The treatment residues from the two treatment units 
are then co-disposed in an on-site, Subtitle D treatment surface 
impoundment. The first treatment unit, the spent ore residue treatment 
unit, treats the following two sodium dichromate manufacturing 
wastestreams:

--spent post-neutralization ore residue (Bevill exempt after treatment)
--caustic filter sludge from filtration of sodium hydroxide

    We consider caustic filter sludge to be a wastestream associated 
with the production of sodium hydroxide rather than a sodium dichromate 
manufacturing waste. Nevertheless, we chose to exercise our discretion 
to

[[Page 55744]]

evaluate the risk posed by the treated and untreated forms of this 
residue.
    The spent ore residue treatment unit treatment tanks have both 
secondary containment and covers. Treatment consists of converting the 
hexavalent chromium in the units to trivalent chromium. Trivalent 
chromium is typically a less soluble and less toxic form of chromium. 
Ore residue wastes are not Bevill exempt and therefore beyond the scope 
of the consent decree until treatment occurs. Therefore, we have 
evaluated the potential for releases from these treatment tanks. We 
assume the tanks are intact structures with minimal potential for 
releases to groundwater. We believe the covers on the tanks reduce the 
potential for air releases. Also, the wastes do not contain volatile 
constituents.
    The second treatment unit, the wastewater treatment unit, treats 
the following two sodium dichromate manufacturing wastestreams:

--sodium chromate evaporation unit wastewaters
--sodium dichromate evaporation unit wastewaters

    The wastewater treatment unit also treats remediation well water 
and stormwater, two types of contaminated media which are outside the 
scope of the consent decree. The two wastewaters within the scope of 
the consent decree make up approximately 9% of the total volume of the 
wastes entering the treatment unit. The facility converts hexavalent 
chromium to less toxic trivalent chromium during this treatment 
process. The tanks do not have covers.
    We evaluated the tanks for potential releases to the environment. 
We assumed the tank structures were intact and therefore posed minimal 
potential for releases to groundwater. Since the wastewaters contain no 
volatile constituents, we found no significant potential for air 
releases. We are proposing not to list the wastes in these treatment 
tanks.
    The facility disposes the treatment materials from the two tank 
systems described above in an on-site surface impoundment. We describe 
that surface impoundment in the next section.
    (b) Residuals Disposed of On-Site. (i) Commingled reduced chromium 
treatment residues. The treatment residues from the two treatment tank 
systems described in the section above are piped directly to the 
facility's on-site, double-lined, Subtitle D surface impoundment for 
co-disposal and dewatering. Of the several treatment residues 
contributing to the mass of reduced chromium treatment residue disposed 
of in the Subtitle D surface impoundment at the Texas facility, only 
three fall within the scope of today's listing proposal: residue from 
treatment of caustic filter sludge, residue from treatment of sodium 
chromate evaporation unit wastewaters, and residue from treatment of 
sodium dichromate evaporation unit wastewaters. Residues from the 
treatment of post-neutralization spent ore residue are Bevill exempt 
mineral processing wastes beyond the scope of today's listing proposal 
(see section III.F.12.c). Stormwater and remediation well water are 
contaminated media whose treatment residues we also consider to be 
beyond the scope of the consent decree (see section III.B). Therefore, 
we do not consider the risks posed by these residues.
    According to information the facility submitted in their RCRA 
Section 3007 Survey response, the only potential constituent of concern 
in the untreated sodium dichromate evaporation unit wastewater, sodium 
dichromate evaporation unit wastewaters, and the caustic filter sludge 
is chromium, measured at a level of 0.5 mg/L, 0.5 mg/L and 20 mg/kg, 
respectively. Therefore, chromium is the only constituent we considered 
when assessing the level of risk from sodium dichromate evaporation 
unit wastewater, sodium chromate evaporation unit wastewater, and 
caustic filter sludge treatment residues.
    Of the total chromium contributed to the co-disposed reduced 
chromium treatment residue by all incoming wastes, the sodium 
dichromate evaporation unit wastewater, sodium chromate evaporation 
unit wastewater, and the caustic filter sludge contribute 
5 x 10-5 percent by weight. This estimate is based on 
calculations using information the Texas facility provided to us on 
chromium contents and tonnages of wastes entering the spent ore residue 
treatment unit and the wastewater treatment unit on-site. Both the 
information and the calculations are described further in the ``Sodium 
Dichromate Listing Background Document for the Inorganic Chemical 
Listing Determination.''
    The facility did not provide us with TCLP, SPLP, or total 
constituent analyses for the co-disposed reduced chromium treatment 
residues. However, the facility did report to us that reduced chromium 
treatment residues do not exceed the TC level of 5.0 mg/L according to 
TCLP analysis. In addition, the facility reported that for the time 
period between October 1, 1998 and December 31, 1998, weekly samples of 
reduced chromium treatment residues from the spent ore residue 
treatment unit analyzed with a facility-modified version of the TCLP 
ranged between 0.16 and 1.75 mg/L chromium (see ``Sodium Dichromate 
Listing Background Document for the Inorganic Chemical Listing 
Determination'' for details). Therefore, conservatively assuming a 
maximum TCLP chromium leaching level of 4.9 mg/L and assuming that the 
percent contribution by the three wastes to total chromium entering the 
treatment units is equal to their percent contribution to total 
chromium leaching from treatment residues exiting the treatment units, 
the caustic filter sludge, sodium chromate evaporation unit 
wastewaters, and sodium dichromate evaporation unit wastewaters were 
responsible for TCLP chromium leaching levels of 2.45 x 10-6 
mg/L.
    The HBL for hexavalent chromium is 0.047 mg/L and 23 mg/L for 
trivalent chromium. The AWQC for hexavalent chromium is 0.011 mg/L and 
0.74 mg/L for trivalent chromium. At a leaching level of 
2.45 x 10-6 mg/L, the leachable chromium contribution of the 
caustic filter sludge, sodium chromate evaporation unit wastewaters, 
and the sodium dichromate evaporation unit wastewaters indicates a very 
low level of risk to groundwater from potential releases from the 
surface impoundment.
    The waste is metallic and inorganic in nature and therefore we do 
not expect it to contain volatile constituents of concern. We do not 
believe, therefore, that this waste poses a risk via airborne pathways. 
Given the low level of chromium leachate deriving from the three 
treatment residues within the scope of today's listing proposal and 
placed into the surface impoundments, we propose not to list residues 
deriving from the treatment of caustic filter sludge, sodium chromate 
evaporation unit wastewater, and sodium dichromate evaporation unit 
wastewater.
    (ii) Commingled treated wastewaters. Treated wastewaters commingled 
with the commingled reduced chromium treatment residues separate from 
these solid residues in the Texas facility's surface impoundment 
disposal unit. These liquids are not Bevill exempt wastes (see Section 
III.F.12.3). The solids suspended in the wastewaters are a mixture of 
Bevill exempt and non-Bevill exempt treatment residues. The liquid 
portion, the majority of this wastestream, is a mixture of non-Bevill 
exempt residues, some of which are within the scope of this listing 
determination, and some of which derive from treatment of contaminated

[[Page 55745]]

media and are therefore not within the scope of this listing 
determination.
    The commingled treated wastewaters discharge from the surface 
impoundment through an NPDES-permitted outfall after passing through 
sand filters to remove residual solids (see discussion below in Section 
III.F.12.e(2)(c)(ii). We therefore assume that the chemical composition 
of the treated wastewaters in the surface impoundment is very similar 
to that of the NPDES permitted discharge. We used NPDES permit 
discharge data, available to the public from the EPA's Envirofacts 
database,\44\ as a surrogate for characterization of this wastewater 
(see discussion of SPLP filtrate in Section III.E.3). The exposure 
pathway of concern is the groundwater underlying the facility's 
disposal units and consumption of the groundwater as drinking water.
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    \44\ http://www.epa.gov/enviro/index_java.html
---------------------------------------------------------------------------

    According to the Texas facility's 1998 NPDES monitoring data, the 
facility discharged an average of 0.018 pounds of hexavalent chromium 
each day through their internal NPDES outfall. Given the amount of 
treated wastewater the facility reported as discharge from the surface 
impoundment in 1998, we estimate that the facility produced an NPDES 
effluent with an average hexavalent chromium concentration of 0.016 mg/
L. This concentration is less than the HBL for hexavalent chromium 
(0.047 mg/L).
    According to the Texas facility's NPDES monitoring data for 1998, 
the facility released an average of 0.46 pounds of combined hexavalent 
and trivalent chromium per day. Making the conservative assumption that 
all 0.46 pounds of chromium are trivalent chromium and given the amount 
of treated wastewater discharged in 1998, we estimated that the 
facility produced an NPDES effluent with an average chromium 
concentration of 0.41 mg/L, which is less than 23 mg/L, the HBL for 
trivalent chromium.
    Wastes in the surface impoundment dewater and the resulting 
wastewaters pass out of the surface impoundment and through tank-based 
sand filters. From the sand filters, the treated wastewaters then 
discharge through an NPDES-permitted outfall. These wastewaters are a 
mixture of non-Bevill exempt and Bevill exempt treatment residues, and 
other treatment residues beyond the scope of the consent decree. We did 
not find any significant potential for releases from the sand filter 
tanks. (We assess spent filter media from the sand filters separately 
in Section III.F.12.e(2)(c)(ii) We concluded that the NPDES discharge 
is exempt from RCRA regulation.
    (c) Residuals Disposed of Off-Site. (i) Process filters and 
membranes, baghouse bags, chromium-contaminated empty containers, and 
other plant wastes. The Texas facility reports in their RCRA Section 
3007 Survey response that process filters and membranes and baghouse 
bags from their facility exceed the TC level for chromium and are coded 
D007. The facility also reports that they produce empty containers and 
other plant wastes contaminated with chromium which are also coded 
D007. The facility stores these hazardous wastes in a closed rolloff 
bin on-site before sending them off-site to a permitted Subtitle C 
hazardous waste facility for treatment and landfill disposal. These 
wastes are sufficiently managed under current RCRA Subtitle C 
regulations and therefore we propose not to list these wastes.
    (ii) Spent sand filter sands. The Texas facility generates waste 
sand material from the sand filters which filter treated wastewaters 
prior to their NPDES permitted discharge from the facility's on-site 
surface impoundment. The purpose of the sand filters is to remove any 
residual solids which fail to settle in the surface impoundment. Since 
the majority of the solids settle in the surface impoundment, the sand 
filters captures smaller amounts of reduced chromium treatment residue. 
Approximately 2 MT of spent sand filter sand is disposed of every two 
years. The facility stores the spent sand in non-hazardous soil bins 
on-site before disposing of it at an off-site Subtitle D industrial 
landfill.
    According to the Texas facility, this residue does not exhibit any 
constituent above the TC level according to TCLP leachate analysis. 
Residues from treatment of caustic filter sludge, sodium chromate 
evaporation unit wastewaters, and sodium dichromate evaporation unit 
wastewaters are the only residues contributing to the potential 
constituent of concern levels in the spent sand filters which also fall 
within the scope of today's listing proposal. All other wastes are 
either Bevill exempt wastes or treatment residues from contaminated 
media, neither of which falls within the scope of the consent decree.
    Chromium was the only potential constituent of concern detected in 
the sodium chromate evaporation unit wastewaters, sodium dichromate 
evaporation unit wastewaters and the caustic filter sludge, and is 
therefore the only potential constituent of concern we considered in 
the spent sand filter sands. As discussed in the section on commingled 
reduced chromium treatment residues, the residues contribute 
5 x 10-5 percent of the total chromium mass entering the 
spent ore residue treatment unit. Assuming a maximum TCLP chromium 
leaching level of 4.9 mg/L, and assuming that the percent contribution 
to total chromium by the three wastes entering the treatment units is 
equal to their percent contribution to total chromium leaching from 
treatment residues exiting the treatment units, the caustic filter 
sludge, sodium chromate evaporation wastewaters, and sodium dichromate 
evaporation unit wastewaters were responsible for TCLP chromium 
leaching levels of 2.4 x 10-6 mg/L.
    The HBL for hexavalent chromium is 0.047 mg/L and 23 mg/L for 
trivalent chromium. The AWQC for hexavalent chromium is 0.011 mg/L and 
0.74 mg/L for trivalent chromium. At a level of 2.4 x 10-6 
mg/L, the leachable chromium contribution of the sodium dichromate 
evaporation unit wastewater, the sodium chromate evaporation 
wastewaters, and the caustic filter sludge presents a very low level of 
risk.
    The waste is metallic and inorganic in nature, and therefore we do 
not expect it to contain volatile constituents of concern. We do not 
believe, therefore, that this waste poses a risk via airborne pathways. 
Given the low level of risk posed by the contribution of constituents 
in the spent filter sands attributable to caustic filter sludge, sodium 
chromate evaporation unit wastewaters, and sodium dichromate 
evaporation unit wastewater treatment residue, the absence of volatile 
constituents of concern, and the relatively small volume of the total 
waste, we propose not to list this waste.
13. Sodium Phosphate From Wet Process Phosphoric Acid
    a. Summary. We propose not to list any wastes from the production 
of sodium phosphate from wet process phosphoric acid as hazardous under 
subtitle C of RCRA. Many of these secondary materials are piped back 
into the production process; other wastes are discharged to a permitted 
publicly-owned treatment works (POTW). Other materials are sent to 
Subtitle D industrial landfills. After an analysis of waste management 
practices and potential exposure pathways, we conclude that there are 
no risk pathways of concern. These wastes do not meet the criteria set 
out at 40 CFR 261.11(a)(3) for listing as hazardous.
    b. Description of the sodium phosphate industry. Sodium phosphate 
is the more general chemical name for

[[Page 55746]]

a wide variety of salts produced from the neutralization of phosphoric 
acid. Some of the salts produced by the facilities in this industry are 
monosodium dihydrogen phosphate (H2NaPO4), 
disodium monohydrogen phosphate (HNa2PO4), 
trisodium phosphate (Na3PO4), sodium 
hexametaphosphate (Na4P 4O12), and 
sodium tripolyphosphate (Na5P3O10).
    The various phosphate salts produced are used for a wide variety of 
purposes, ranging from a water soluble solid acid and pH buffer for 
acidic cleaners to products manufactured for the food industry \45\. 
Sodium phosphate is produced from wet process phosphoric acid by two 
manufacturing companies at four locations in the United States. For 
more detailed information concerning this industry, see ``Sodium 
Phosphate Listing Background Document for the Inorganic Chemical 
Listing Determination'' in the docket for today's proposal.
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    \45\ In this preamble, we often refer to sodium phosphate 
produced for the food industry as ``food grade.'' The Food and Drug 
Administration (FDA), Department of Health and Human Services, 
refers to the various sodium phosphates used in the food industry as 
``substances generally recognized as safe'' (GRAS). The FDA states 
that: ``This substance is generally recognized as safe when used as 
in accordance with good manufacturing practice.'' (See, for example, 
21 CFR 182.1778, 182.6290, 182.6778, and 182.8778.) In deciding 
whether a food additive should be approved, the FDA considers the 
composition and properties of the substance, the amount likely to be 
consumed, its probable long-term effects and various safety factors.
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    The processes for monosodium dihydrogen phosphate, disodium 
monohydrogen phosphate, and trisodium phosphate are similar except for 
the ratio of phosphoric acid to soda ash at the reactor stage and the 
type, size and construction of the crystallizing and drying equipment. 
The raw materials are water, phosphoric acid, soda ash, and caustic. 
The purified phosphoric acid is manufactured elsewhere through the wet-
acid purification method and is food grade. The process starts with a 
reaction between phosphoric acid, soda ash, and caustic. The solution 
is used to make the monosodium dihydrogen phosphate, which passes 
through a polishing filter before shipment to customers. The sodium to 
phosphorus ratio of the solution is adjusted with caustic to make 
disodium monohydrogen phosphate and trisodium phosphate. These 
solutions are filtered and then crystallized. The crystals from each 
process pass through dryers. The finished product is packaged or 
shipped in bulk.
    Sodium hexametaphosphate and sodium tripolyphosphate are also 
produced from food-grade phosphoric acid and soda ash. Both processes 
start with a reaction between phosphoric acid and soda ash. For the 
sodium hexametaphosphate process, the product is fed to a furnace which 
melts the mix and converts it to sodium hexametaphosphate. For the 
sodium tripolyphosphate process, the reaction discharge is dried and 
heat treated in a converter to convert it to sodium tripolyphosphate. 
In both processes, the product is cooled, sized, stored, and packaged 
for shipment.
    c. What kinds of wastes are generated by these processes? A brief 
description of the waste categories, how they are generated, their 
volumes across the industry, and how they are managed is presented in 
Table III-34:

                                Table III-34.--Sodium Phosphate Production Wastes
----------------------------------------------------------------------------------------------------------------
          Waste category               1998 Volume  (MT)               Source             Management practices
----------------------------------------------------------------------------------------------------------------
Filter press cakes...............  120......................  Product polishing.......  Recycled or Subtitle D
                                                                                         landfill.
Mix area filters.................  0.009....................  Product polishing.......  Subtitle D landfill.
Dust collector filter bags.......  2.1......................  Drying and grinding       Subtitle D landfill.
                                                               processes.
Scrubber waters and effluents....  32.......................  Process vapor scrubbers.  POTW or recycled.
Product dust collected...........  Not reported.............  Drying and grinding       Recycled or Subtitle D
                                                               processes.                landfill.
Off-specification product........  771......................  Off-specification         Recycled or Subtitle D
                                                               grinding or customer      landfill.
                                                               returns.
----------------------------------------------------------------------------------------------------------------

    For those scenarios where secondary materials (filter press cakes, 
product dust, off-specification product, and scrubber water) are piped 
back to the production process, we could identify no potential route 
for significant exposure prior to reuse. In addition, we evaluated all 
wastes generated after reinsertion of these materials into the process 
and we do not believe that these secondary materials present 
significant threats. Also, off-specification product, when reinserted 
without reclamation into the process from where it originated, is not a 
solid waste. For those scenarios where wastes are discharged via the 
facility's common sewage line to permitted publicly-owned treatment 
works (POTWs), these wastes are excluded from RCRA (40 CFR 
261.4(a)(1)(ii)). For those scenarios where wastes are sent to 
industrial subtitle D landfills, we performed a risk assessment to help 
us determine whether these risks warranted listing.
    d. Agency evaluation. (1) Filter press cake and mix area filters.
How Was This Waste Characterized?
    We collected two samples of this residual at one facility. Based on 
our assessment of the raw materials and production processes used 
across the industry, we believe these samples are representative of the 
range of waste characteristics at the other three sodium phosphate 
production facilities. Constituents detected above their HBLs are 
summarized in Table III-35.

             Table III-35.--Characterization of Filter Press Cakes From Sodium Phosphate Production
----------------------------------------------------------------------------------------------------------------
                                                              Total  (mg/   TCLP  (mg/   SPLP  (mg/
                          Parameter                               kg)           l)           l)      HBL  (mg/l)
----------------------------------------------------------------------------------------------------------------
Primary filter press cake (Sample RCH-1-SP-01):
    Antimony................................................          0.5          0.5       0.0298        0.006
    Thallium................................................            2            2       0.0055        0.001

[[Page 55747]]

 
Tray filter cake (Sample RCH-1-SP-02):
    Antimony................................................          0.5          0.5        0.025        0.006
    Thallium................................................            2            2       0.0079        0.001
----------------------------------------------------------------------------------------------------------------

What Management Scenarios Were Assessed and How Was the Risk Assessment 
Established?
    These wastes go to industrial subtitle D landfills and we therefore 
determined that we would model the scenario of off-site disposal in an 
industrial D landfill. We assessed the off-site landfill scenario using 
the hydrogeologic properties associated with the geographic areas where 
the landfills reported in the survey are located.
    We gave the SPLP results primary consideration as there is no 
reported management in municipal landfills (where the TCLP results 
would be relevant). Based on the sampling results summarized above, we 
decided that modeling was necessary for two constituents of concern: 
antimony and thallium. For antimony, we used one-half of the detection 
limit as a model input for sample RCH-1-SP-02. We used the 
probabilistic approach for an off-site industrial Subtitle D landfill 
described in section III.E of today's proposal.
What Is EPA's Listing Rationale for This Waste?
    From the results of the risk assessment, summarized below in Table 
III-36, neither antimony nor thallium (the constituents of concern) 
pose a substantial present or potential hazard to human health and the 
environment. The hazard quotients for both constituents, for both the 
adult and child exposure scenarios, are less than 0.008 at the 95th 
percentile. As a matter of policy, EPA generally does not consider 
listing wastes with predicted hazard quotients of less than 1.0. We see 
no special concerns warranting an exception to this policy. Therefore, 
we believe that these wastes do not warrant listing.
    For the mix area filters, the location of these filters indicates 
that any contaminants found would be similar to those of the filter 
press cake. Given that our evaluation of the much larger volume filter 
press cake yielded no significant risk, we are also proposing not to 
list the very small volume mix area filters.
    For a more complete description of these analyses, see ``Risk 
Assessment for the Listing Determinations for Inorganic Chemical 
Manufacturing Wastes'' in the docket for this proposed rulemaking.

    Table III-36.--Probabilistic Risk Results for Filter Press Cakes
------------------------------------------------------------------------
                                             Antimony        Thallium
                                         -------------------------------
               Percentile                  Adult   Child   Adult   Child
                                            HQ      HQ      HQ      HQ
------------------------------------------------------------------------
Industrial landfill:
90th....................................   0.001   0.003   0.002   0.003
95th....................................   0.004   0.008   0.004   0.008
------------------------------------------------------------------------

    (2) Dust collector filter bags.

How Was This Waste Characterized?

    We collected one sample of this residual. Based on our assessment 
of the raw materials and production processes used across the industry, 
we believe this sample is representative of similar wastes at the other 
three sodium phosphate production facilities. The waste constituents 
detected at levels above their HBLs are summarized in Table III-37:

Table III-37.--Characterization of Dust Collector Filter Bag From Sodium
                          Phosphate Production
                          [Sample RCH-1-SP-03]
------------------------------------------------------------------------
                                         Total
               Parameter                 (mg/    TCLP     SPLP     HBL
                                          kg)   (mg/l)   (mg/l)   (mg/l)
------------------------------------------------------------------------
Antimony..............................    48.8     0.5    0.309    0.006
Arsenic...............................     0.5     0.5   0.0064   0.0007
------------------------------------------------------------------------

What Management Scenarios Were Assessed and How Was the Risk Assessment 
Established?
    Industry reported that this waste is managed in off-site industrial 
D landfills. We assessed this scenario. Antimony and arsenic are the 
constituents of concern.
    Because the volume of this waste is relatively small, we first used 
the de minimis waste quantity screening analysis (described in section 
III.E.3) to screen the potential risk to groundwater associated with 
landfilling this waste. We found that the SPLP data for arsenic screens 
out because the waste volume is insufficient to release arsenic at 
levels of concern. For a more complete description of this analysis, 
see ``Risk Assessment for the Listing Determinations for Inorganic 
Chemical Manufacturing Wastes'' in the docket for this proposed 
rulemaking.
    The detected SPLP levels for antimony did not screen out using the 
de minimis volume analysis. We conducted full groundwater modeling for 
the industrial landfill scenario for this constituent. We assessed the 
off-site landfill scenario using the probabilistic approach for off-
site landfills described in section III.E.
What Is EPA's Listing Rationale for This Waste?
    From the results of the risk assessment, summarized below in Table 
III-38, antimony (the constituent of concern) does not pose a 
substantial present or potential hazard to human health and the 
environment. The hazard quotients for antimony, for both the adult and 
child exposure scenarios, are less than 0.007 at the 95th percentile. 
As a matter of policy, EPA generally does not consider listing wastes 
with predicted hazard quotients of less than 1.0. We see no special 
concerns warranting an exception to this policy. Therefore, we believe 
that this waste does not warrant listing. For a more complete 
description of this analysis, see ``Risk Assessment for the Listing 
Determinations for Inorganic Chemical Manufacturing Wastes'' in the 
docket for this proposed rulemaking.

    Table III-38.--Probabilistic Risk Results for Dust Collector Bags
------------------------------------------------------------------------
                                                            Antimony
                                                       -----------------
                      Percentile                         Adult    Child
                                                           HQ       HQ
------------------------------------------------------------------------
Industrial landfill:
    90th..............................................    0.001    0.002
    95th..............................................    0.003    0.003
------------------------------------------------------------------------

    (3) Scrubber waters and effluents. We did not evaluate scenarios 
where these secondary materials are piped back into the production 
process because there is no potential for exposure. For those scenarios 
where wastes are managed in a tank, the impervious nature of the 
construction materials (concrete,

[[Page 55748]]

fiberglass, or steel) of tanks are unlikely to result in releases to 
groundwater in all but the most catastrophic scenarios. We also are not 
concerned with potential air releases from these tanks as neither 
volatile contaminants nor airborne particulates are likely to be 
present in these aqueous wastes. For those scenarios where wastes are 
discharged via the facility's common sewage line to POTWs, these wastes 
are excluded from RCRA (40 CFR 261.4(a)(1)(ii)). Furthermore, these 
discharges are regulated by the Clean Water Act pretreatment standards. 
They do not warrant listing. We propose not to list this waste.
    (4) Product dust collected. All collected dust that can be recycled 
is recycled back into the production process. Due to production 
constraints, some portion of this collected product dust cannot be 
recycled back to the process and is instead sent to an industrial 
Subtitle D landfill. However, this landfilled product is still food-
grade product. Because this ``waste'' is, in fact, food-grade product, 
we believe it unlikely that it contains any constituent exceeding 
health-based limits based on ingestion. Therefore, we propose not to 
list this waste.
    (5) Off-specification product. Much of this material is reused in 
the production process with no potential for exposure. However, because 
of production constraints, they cannot always work all of this material 
back into the process, and it must be disposed in an industrial 
subtitle D landfill. In all cases, product is rejected by a customer 
because of physical property problems--i.e., particle size--rather than 
chemical problems or contaminants. Because this ``waste'' is, in fact, 
food-grade product, we believe it unlikely that it contains any 
constituent exceeding health-based limits based on ingestion. 
Therefore, we propose not to list this waste.
14. Titanium Dioxide
    a. Summary. We evaluated wastes from the production of titanium 
dioxide and propose to list one waste and not to list all of the 
others. Certain wastes from titanium dioxide production are exempt 
mineral processing wastes and were not assessed as part of today's 
listing determination because they are outside the scope of the consent 
decree. We are proposing to list nonwastewaters from the chloride 
ilmenite process (unless otherwise exempted).

K178  Nonwastewaters from the production of titanium dioxide by the 
chloride-ilmenite process. (T) [This listing does not apply to chloride 
process waste solids from titanium tetrachloride production exempt 
under section 261.4(b)(7)]

    We propose not to list the remainder of the wastes generated by 
this sector. We do not believe these wastes pose threats to human 
health or the environment that warrant listing. We have not identified 
risks of concern associated with the current management of these wastes 
that support a listing determination. Our findings, however, do not 
change the applicability of existing standards and regulations, such as 
the hazardous waste characteristics, to these wastes and this industry.
    b. Description of the titanium dioxide industry. There are nine 
facilities producing titanium dioxide. There are three distinct 
processes currently in use: the chloride process, the sulfate process, 
and the chloride-ilmenite process. Six facilities use the chloride 
process. Two of these six facilities also produce titanium dioxide via 
the sulfate process. Three separate facilities use only the chloride-
ilmenite process.
    Chloride Process. In the chloride process, rutile or high-grade 
ilmenite is converted to titanium tetrachloride (TiCl4). The 
conversion takes place in a chlorinator in the presence of chlorine gas 
with petroleum coke added as a reductant. All U.S. producers of 
TiCl4 use fluidized bed chlorinators. Vent gases from the 
chlorinator are scrubbed prior to venting to the atmosphere. Non-
volatile metal chlorides and unreacted coke and ore solids are removed 
from the gaseous product stream. The facilities also generate waste 
acid, which they mingle with coke and ore solids before treatment. Vent 
gases from the chlorinator are scrubbed prior to venting to the 
atmosphere. The volatile TiCl4 and other volatile metal 
compounds such as vanadium oxychloride, exit the chlorinator as 
overhead vapor. The gaseous product stream is purified to separate the 
titanium tetrachloride from other metal chloride impurities using 
processes such as partial condensation and chemical treatment. Finally, 
vanadium compounds, which have boiling points close to that of 
TiCl4, are removed from the titanium tetrachloride by 
complexing with mineral oil and reducing with hydrogen sulfide, or by 
complexing with copper. The purified TiCl4 is then oxidized 
to TiO2, driving off chlorine gas, which is recycled to the 
chlorinator. The pure TiO2 is slurried and sent to the 
finishing process which includes milling, addition of inorganic and 
organic surface treatments, and/or spray drying of the product 
TiO2. The product can be sold as a packaged dry solid or a 
water-based slurry.
    Sulfate Process. In the sulfate process, ilmenite ore or slag with 
high TiO2 content is digested with sulfuric acid, forming a 
porous cake; this cake is further dissolved by dilute acid to form 
titanyl sulfate (TiOSO4). Iron may be added to the digestion 
process to ensure that iron impurities remain in the ferrous 
(Fe2+) state so that the eventual TiO2 product 
can be easily washed. The titanyl sulfate solution is then clarified, 
yielding a waste sulfate digestion sludge, and then concentrated 
through vacuum evaporation. The filtered titanyl sulfate solution is 
vacuum-evaporated a second time and hydrolyzed to precipitate hydrated 
titania (TiO(OH)2). The titania hydrate is then filtered and 
washed, yielding filtrate waste and wastewater, respectively, before 
being calcined at 1,000 deg.C to produce the TiO2 product.
    Chloride-Ilmenite Process. In the chloride-ilmenite process, 
ilmenite ore is converted to titanium tetrachloride. As in the chloride 
process, the chloride-ilmenite process takes place in a chlorinator in 
which the ore is chlorinated in the presence of coke as a reducing 
agent. Vent gases from the chlorinator are scrubbed prior to venting to 
the atmosphere. Non-volatile metal chlorides and unreacted coke and ore 
solids are removed from the gaseous product stream. The gaseous product 
stream then is purified further to separate the titanium tetrachloride 
from other volatile metal chloride impurities, including ferric 
chloride (FeCl3) which is present in higher concentrations 
than the chloride process due to the high iron content in the ore. The 
separation is done via condensation and chemical treatment. The process 
for converting the purified TiCl4 product stream to 
TiO2 is similar to that used in the chloride process, as 
described above.
    c. What kind of wastes are generated by these processes?. The 
wastes generated by the titanium dioxide sector are described in 
overview below, organized by process. Additional detail on these wastes 
is provided in the background document for this sector.
    The wastes generated by the chloride process include:

--Commingled wastewaters, including process and non-process wastewaters 
from chlorinator coke and ore solids recovery, reaction and chemical 
tank storage scrubbers, product finishing operations, wastewater 
treatment and chlorinator solids decantation, and on-site landfill 
leachate.
--Chloride process waste solids from titanium tetrachloride production 
(exempt as mineral processing wastes, see 40 CFR 261.4(b)(7)).

[[Page 55749]]

--Wastewater treatment sludges generated by facilities that have 
chloride-only processes (exempt mineral processing wastes at those 
facilities with no contribution of solids from oxidation and finishing)
--Waste sands from finishing (milling) of the titanium dioxide product 
and scouring of oxidation process units.
--Vanadium wastes generated in the purification process.

    The wastes generated by the sulfate process (used at two plants 
that also use the chloride process) include:

--Primary and secondary gypsum, which is produced when the waste 
sulfuric acid generated from the filtering of titanium dioxide hydrate 
solution is neutralized with calcium carbonate.
--Digestion sludge from the clarification of the titanyl sulfate liquor 
that is produced during the acid digester step.
--Wastewaters from the sulfuric acid digestion scrubber which removes 
acidic components and entrained solids from reaction gases, evaporator 
condensate from the precipitation unit, the calciner scrubber, the 
sulfate waste sludge settling pond supernatant, and the primary and 
secondary gypsum precipitation units. These wastewaters are commingled 
with wastewaters from the chloride process.
--Wastewater treatment sludges. These wastewater treatment sludges are 
generated from commingled chloride process and sulfate process 
wastewaters by facilities that have both processes. The wastewater 
treatment consists of elementary neutralization and precipitation or 
filtration.
--Acids from intermediate titanium product filtration/bleaching units 
and product calciner overhead scrubbers.
--Product milling sand from finishing operations.

    The wastes generated by the chloride-ilmenite process include:

--Coke and ore solids (exempt as mineral processing wastes, see 40 CFR 
261.4(b)(7)) that are not consumed by the chlorination process. These 
solids are conveyed through the process as part of various 
wastestreams.
--Waste acid (metal chloride) solution, usually called ferric or iron 
chloride, that is separated from the gaseous titanium tetrachloride 
product stream and acidified.
--Process and non-process wastewaters from reaction and oxidation 
scrubbers, reactant and treatment chemical storage scrubbers, product 
finishing, HCl storage vent scrubber, oxidation unit tank and equipment 
vents, supernatant or filtrate from coke and ore solids management and 
wastewater treatment disposal impoundments. The wastewaters are 
commingled prior to being introduced into the wastewater treatment 
system.
--Other spent scrubber waters from the reaction fume disposal system. 
The wastewaters are pretreated and are subsequently commingled with 
other wastewaters prior to being introduced to the wastewater treatment 
system.
--Non-exempt non-wastewaters, including the portion of wastewater 
treatment solids derived from the neutralization of process and non-
process wastewaters from oxidation and finishing, and solids from 
ferric chloride filtration.
--HCl from the reaction scrubber.
--Additive feeder vent filter solids generated in the oxidation 
process.
--Vanadium waste generated in the purification process.
--Off-specification titanium dioxide product.
--Rail car product washout wastewater.
--Waste sand removed from a reactor purge stream (coke and ore solids)

    Table III-39, below, summarizes our information about the wastes 
generated rom the production of titanium dioxide.

                                     Table III-39.--Titanium Dioxide Wastes
----------------------------------------------------------------------------------------------------------------
                                 Number of
        Waste category          generators     1998  volumes (MT)   Reported hazard codes   Management practices
----------------------------------------------------------------------------------------------------------------
Commingled chloride process              4   7,614,358............  D002, D007...........  Neutralization,
 wastewaters.                                                                               solids settling,
                                                                                            NPDES discharge.
Chloride process solids                  6   1,200,000............  none.................  On-site impoundments,
 (Bevill exempt).                                                                           on-site Subtitle D
                                                                                            landfills.
Waste sands from oxidation,              3   9,485................  none.................  On-site industrial
 milling and scouring.                                                                      Subtitle D landfill;
                                                                                            off-site industrial
                                                                                            Subtitle D landfill.
Gypsum from sulfate process..            2   \46\ 69,500..........  none.................  On-site waste pile
                                                                                            storage; on-site
                                                                                            industrial Subtitle
                                                                                            D landfill; sold for
                                                                                            various uses.
Digestion scrubber water.....            2   2,000,333............                         Neutralization in
                                                                                            dedicated
                                                                                            impoundment;
                                                                                            commingled with
                                                                                            other wastewaters.
Digestion sludge from sulfate            2   41,494...............  D002.................  Unlined impoundment,
 process.                                                                                   dewatering, on-site
                                                                                            industrial Subtitle
                                                                                            D landfill.
Commingled wastewaters from              2   16,184,031...........  none.................  Neutralization,
 the chloride and sulfate                                                                   solids settling in
 process.                                                                                   unlined surface
                                                                                            impoundments, NPDES
                                                                                            discharge.
Wastewater treatment sludges             2   159,121..............  none.................  Dewatering, on-site
 from commingled chloride and                                                               industrial Subtitle
 sulfate process (partially                                                                 D landfill.
 Bevill exempt).
Waste acid (ferric chloride)             3   1,883,000............  D002, D007, D008.....  On-site hazardous
 from chloride-ilmenite                                                                     waste underground
 process.                                                                                   injection; reuse as
                                                                                            raw material in
                                                                                            sodium chloride
                                                                                            production; storage
                                                                                            in tanks and unlined
                                                                                            impoundment prior to
                                                                                            sale as water and
                                                                                            wastewater treatment
                                                                                            reagent.
Chloride ilmenite process                3   not reported.........  none.................  On-site dewatering;
 solids (Bevill exempt).                                                                    on-site Subtitle D
                                                                                            industrial landfill;
                                                                                            on-site unlined
                                                                                            impoundment; various
                                                                                            reuses.
Non-exempt nonwastewaters                3   14,600...............  none.................  On-site dewatering;
 from the chloride-ilmenite                                                                 on-site Subtitle D
 process.                                                                                   industrial landfill;
                                                                                            on-site unlined
                                                                                            impoundment; various
                                                                                            reuses.
HCl from reaction scrubber,              3   not reported.........  D002.................  On-site wastewater
 chloride-ilmenite process.                                                                 treatment, on-site
                                                                                            reuse.
Commingled wastewaters from              3   13,556,000...........  none.................  On-site
 the chloride-ilmenite                                                                      neutralization,
 process.                                                                                   solids settling,
                                                                                            NPDES discharge.

[[Page 55750]]

 
Additive vent filter solids              1    1...................  none.................  Off-site Subtitle D
 from chloride-ilmenite                                                                     industrial landfill.
 process.
Vanadium waste from the                  4   not reported.........  none.................  Returned to reaction
 chloride-ilmenite and                                                                      area for TiCl 4
 chloride process.                                                                          recovery, remaining
                                                                                            vanadium wastes are
                                                                                            incorporated in
                                                                                            solids streams.
Off-spec titanium dioxide                2   563..................  none.................  Off-site Subtitle D
 product.                                                                                   industrial landfill.
Railcar/trailer product                  1   10,000...............  none.................  On-site storage in
 washout.                                                                                   unlined surface
                                                                                            impoundment, on-site
                                                                                            wastewater
                                                                                            treatment.
----------------------------------------------------------------------------------------------------------------
\46\ Additional volumes are used as products.

    The manufacturers also produce materials that are reused in other 
processes that are outside the scope of the consent decree. With one 
exception described below, we did not evaluate these materials, or 
wastes generated during co-product production for the purposes of 
today's listing determinations, because they were outside the scope of 
the consent decree.
    One facility produces sulfur from the treatment of off-gases. 
Because the off-gas is produced from a production unit rather than a 
waste management unit and is conveyed to its destination via piping, 
the gas is not a solid waste. RCRA Section 1004(27) excludes non-
contained gases from the definition of solid waste and thus they cannot 
be considered a hazardous waste. (See 54 FR 50973) Because this gas is 
not a solid waste when produced, we did not evaluate it further for 
purposes of listing.
    d. What wastes from these processes are exempt mineral processing 
wastes? In July of 1988, the U.S. Court of Appeals, for the D.C. 
Circuit in Environmental Defense Fund v. EPA (EDF II), 852 F.2d 1316 
(D.C. Cir. 1988), cert. denied, 489 U.S. 1011(1989), ordered EPA to 
restrict the scope of the Bevill mining waste exclusion, as it applied 
to mineral processing wastes. In response, EPA promulgated rules on 
September 1, 1989 (54 FR 36592) and on January 23, 1990 (55 FR 2322), 
issued a Report to Congress on Wastes from Mineral Processing on July 
31, 1990, and published a regulatory determination published on June 
13, 1991 (56 FR 27300). The list of Bevill exempt wastes is set out at 
40 CFR 261.4(b)(7). We relied on these Bevill rulemakings to determine 
the Bevill status of waste streams in the titanium dioxide sector.
    The production of titanium dioxide results in the generation of 2 
categories of exempt waste: beneficiation wastes and exempt mineral 
processing wastes. These categories are described below.
    The industry reported a number of wastes generated from the storage 
and handling of various raw materials which are exempt because they are 
associated with beneficiation. Solid wastes from the extraction/
beneficiation of ores and minerals are Bevill exempt solid wastes (see 
51 FR 24496, July 3, 1986 and 54 FR 36592, September 1, 1989). These 
wastes are described in the background document for this sector. We 
have not assessed these wastes because they are exempt under 40 CFR 
261.4(b)(7).
    The only relevant mineral processing waste exemption consists of 
``chloride process waste solids from titanium tetrachloride 
production'' (see 40 CFR 261.4(b)(7)(ii)(S)). The consent decree 
mandating today's proposal states in paragraph 1.g that Bevill exempt 
wastes are not within the scope of the consent decree as it applies to 
the inorganic chemical listing determinations, and specifically that 
``chloride process waste solids'' need not be assessed within the 
titanium dioxide sector. Titanium tetrachloride production occurs in 
both the chloride and chloride-ilmenite processes.\47\
---------------------------------------------------------------------------

    \47\ All sulfate process waste solids and liquids are non-exempt 
mineral processing wastes (see 55 FR 2322, January 23, 1990). 55 FR 
2392 noted that all sulfate process waste solids and wastewaters 
from the production of titanium dioxide do not meet the high volume/
low hazard criteria established in the September 1, 1989 Bevill rule 
and therefore were not eligible for continued coverage under the 
Bevill exclusion (see 54 FR 36592).
---------------------------------------------------------------------------

    The chloride process waste solids are generated during the 
chlorination reaction of the titanium ore in the reducing presence of 
coke at elevated temperatures, and are generated from both the chloride 
process and the chloride-ilmenite process. The majority of these solids 
are removed from the reaction area as a mass and are quenched, 
neutralized, settled and disposed as exempt materials. Additional 
solids from the reactor are carried overhead with the TiCl4 product gas 
stream and are subsequently removed in various scrubbing units. 
Although EPA has not previously discussed these solids, we believe that 
they also fall within the exemption. While they are removed from the 
product stream and various other wastes at points other than where the 
majority of the solids are separated from the TiCl4 gas stream, they 
are similarly composed of unreacted ore and coke solids from the 
chlorination reactor. They fit within the plain language of the 
exemption.
    Solids also are generated from the oxidation and finishing stages 
of titanium dioxide production. These solids are non-exempt solid 
wastes (not covered by the exemption). Most titanium dioxide producers 
commingle wastewaters from titanium tetrachloride production with 
wastewaters from oxidation and finishing. To the extent that the 
resultant sludges contain non-exempt solids, we have assessed that 
portion of those solids.
    Due to process variations, each facility using the chloride or 
chloride-ilmenite process generates its exempt solids in slightly 
different ways. The general principles that we used to determine the 
Bevill status of these wastes include the following:

--Extraction and beneficiation ends just before chlorination occurs. 
Wastes generated prior to this point are Bevill exempt, outside the 
scope of the consent decree and therefore not addressed in this 
rulemaking. The chlorinator marks the beginning of mineral 
processing because the ore undergoes a physical/chemical change (see 
54 FR 36619, September 1, 1989). 54 FR 36621 further notes, 
``Likewise, EPA considered titanium tetrachloride produced during 
the titanium chloride [sic] process to be a saleable product; any 
further processing subsequent to its production is considered to be 
chemical manufacturing.''
--Mineral processing ends when titanium dioxide is produced in the 
oxidation unit. Further steps are chemical manufacturing. The Agency 
defines the beginning of oxidation as the beginning of chemical 
manufacturing because the facility is using a saleable mineral 
product, titanium tetrachloride, to produce titanium dioxide (see 54 
FR 366211).

[[Page 55751]]

--The mineral processing exemption only covers solids from the 
production of titanium tetrachloride. These solids, therefore, are 
outside of the consent decree. At least six streams of solid-bearing 
material leave the chlorination reaction area. The status of these 
streams is as follows:

    (1) Titanium tetrachloride going on for further production. All 
wastes formed during further processing of this gaseous product 
stream are chemical manufacturing wastes that are outside the scope 
of the Bevill exemption.
    (2) Solids removed from the gaseous titanium tetrachloride 
stream. These solids are associated with the production of titanium 
tetrachloride. These solids are typically slurried to impoundments 
for storage or disposal and are Bevill-exempt (with one exception 
described below).
    (3) Waste acids. In 1990 and 1998 rulemakings for LDR Phase IV 
(see 63 FR 28601), EPA took the position that the waste acids do not 
meet the high-volume, low-toxicity test and thus are not exempt 
mineral processing wastes.
    (4) Gases going to scrubbers. Offgases from the chlorinators 
pass through various air pollution control systems which generate 
scrubber waters. In 1998, EPA stated that scrubber waters and 
sludges from scrubber waters were not Bevill-exempt. However, as a 
result of the information collection activities associated with 
today's proposal, it is now clear to EPA that gases from the 
chlorinator contain some solids from the chlorinator. We are 
interpreting the exemption today to cover these particles when they 
drop out of scrubber waters to form sludges. (Gas streams and 
wastewaters are not Bevill exempt, even when they are carrying solid 
particles from chlorinator.)
    (5) Solids purged from the reactor. A purge stream from the 
reactor may be taken to reduce silica levels in the reactor. This 
stream is Bevill exempt.
    (6) Recovered solids from the reaction area. Housekeeping 
results in the collection of coke and ore solids from the vicinity 
of the reaction area. These wastes are Bevill exempt.
    In one case, the facility conducts some processing of their 
ferric chloride waste acid (which is subsequently sold as a water 
and wastewater reagent), and generates a solids stream. We consider 
the processing that this facility conducts to be either an ancillary 
process or chemical manufacturing, and thus the subsequent solids 
stream is not generated from mineral processing and therefore is not 
exempt.
What Is The Status of the Mineral Processing Exemption for ``Chloride 
Waste Solids From Titanium Tetrachloride Production'?
    As part of our waste characterization of the titanium dioxide 
sector, we conducted analyses for chlorinated dibenzo-p-dioxins (CDDs) 
and dibenzo-p-furans (CDFs). We were concerned that these compounds 
might be present in the wastes as a result of the chlorination step 
which occurs in the presence of coke, and in fact we found measurable 
levels of these compounds in wastes from the chloride and chloride-
ilmenite processes. These data are presented in the Titanium Dioxide 
Listing Background Document and associated analytical data reports in 
the docket for today's notice. As explained in this background 
document, we believe that these compounds are formed in the 
chlorinator, and are predominantly associated with the exempt mineral 
processing solids (additional details regarding this conclusion are 
provided in the referenced background document). These compounds were 
not assessed, however, as part of the rulemakings which established the 
mineral processing exemptions, and so these results could present new 
issues for these wastes if such compounds were found to pose 
unacceptable risks. During the development of the mineral processing 
exemption, EPA anticipated certain conditions might suggest the 
appropriateness of re-opening these exemptions.\48\ We are considering 
whether we should re-assess the status of these wastes as exempt 
mineral processing wastes. Any reassessment of these wastes would 
involve a separate analysis and opportunity for notice and comment.
---------------------------------------------------------------------------

    \48\ ``If EPA finds that this exemption is not protective of 
human health and the environment and if an examination of titanium 
tetrachloride waste management shows any continuing or new problems, 
the Agency will reconsider this subtitle D determination for 
chloride process waste solids from titanium tetrachloride 
production.'' 56 FR 273000, June 13, 1991.
---------------------------------------------------------------------------

How Did EPA Assess Mixtures of Exempt and Non-Exempt Wastes From the 
Production of Titanium Dioxide?
    There are a number of wastes from the titanium dioxide sector that 
remain partially within the scope of the consent decree because they 
are composed of both exempt and non-exempt solids. Because they are not 
``100 percent exempt'' in composition, we have assessed their potential 
impacts on the environment, and attempted to isolate the risks 
associated with the non-exempt solids and wastewaters. Any assessment 
of the CDD and CDF loading in exempt wastes will involve a separate 
analysis and opportunity for notice and comment.
    Finally, we are assessing one non-exempt waste generated at the 
Delaware facility, non-exempt non-wastewaters from the chloride-
ilmenite process, which contains some CDDs and CDFs at levels exceeding 
our initial screening criteria. We did not, as part of today's listing 
determination, conduct sufficient risk assessment to fully evaluate the 
potential for risks. See section III.F.14.e(10) below.
5. Agency Evaluation
    (1) Commingled wastewaters from the chloride process, including 
wastewaters from coke and ore recovery, scrubber water, finishing 
wastewaters and sludge supernatants.
How Many Facilities Generate This Waste Category and How Is It Managed?
    Four facilities generated commingled wastewaters from the chloride 
process. (As will be discussed further in III.F.14.e(7), two additional 
facilities generate the same wastewaters and commingle them with 
wastewaters from the sulfate process.) Three of the four ``chloride 
only'' facilities treat their wastewaters in surface impoundment-based 
treatment systems; the fourth facility uses a tank-based wastewater 
treatment system. Each of the impoundment systems include unlined 
units. These large volume wastes are generated in excess of 29 million 
metric tons per year. These wastewaters are not Bevill-exempt (but 
convey exempt solids into the wastewater treatment system where those 
solids are removed to form sludges that are comprised of exempt solids 
and non-exempt solids, depending on the specific piping of the plants).
    Many facilities commingle waste hydrochloric acids (generated as 
scrubber water) with their combined wastewaters. Three other 
facilities, however, return waste acids on site or sell the acids for 
reuse. Because these materials have no exposure route of concern, we 
did not further evaluate risk scenarios associated with reuse of this 
material.
What Management Scenarios Were Assessed?
    For this rulemaking, we determined that the surface impoundment 
scenario poses a more significant potential risk than the tank 
scenario, and thus assessed the groundwater pathway for surface 
impoundments. We assessed potential groundwater releases to both 
surface water and drinking water wells. We concluded that the air 
pathway does not present significant risks for these wastes because the 
wastes do not contain volatile organics or other constituents that pose 
risk due to air releases.
How Was This Waste Category Characterized?
    One of the four facilities, located in Hamilton, Mississippi, was 
selected for sampling and analysis. This facility's

[[Page 55752]]

waste is representative of the four chloride-only facilities. The 
sample was collected at the inlet to this facility's surface 
impoundment train.\49\ This sample contained a high level of solids, 
reflecting the facility's practice of managing all waste solids 
(including Bevill-exempt solids) and process wastewaters in the same 
units which serve as settling ponds. To isolate the impact of the 
wastewater on the environment from that of the sludge, we conducted the 
SPLP on the waste matrix, and separately analyzed the filtrate and the 
leachate generated from the leaching step. We are proposing to use the 
filtrate analysis as representative of the wastewater portion of the 
commingled waste matrix (see III.E.2 and 3 for further discussion on 
the use of SPLP filtrate). The analytical results for the constituents 
found to be present in the filtrate at levels exceeding HBLs and/or 
AWQC are presented below in Table III-40 (the Titanium Dioxide Listing 
Background Document contains the full set of analytical results).
---------------------------------------------------------------------------

    \49\ This facility also commingles wastewaters from sodium 
clorate production, which account for approximately 1.7 percent of 
the total 4aste volume.

 Table III-40.--Characterization of Commingled Wastewaters From Chloride
                        Process, Titanium Dioxide
------------------------------------------------------------------------
                               Detected levels in
                              Sample KM-SI-01 (mg/
                                       L)
   Constituent of concern    ----------------------    HBL        AWQC
                                            SPLP
                                Total     Filtrate
------------------------------------------------------------------------
Antimony....................       0.05      0.044      0.006      0.014
Arsenic.....................       0.04      0.001     0.0007   0.000018
Manganese...................       25.9       0.46       0.73       0.05
Molybdenum..................       0.53       0.23      0.078         NA
Thallium....................      0.086  \1\ 0.005      0.001    0.0017
------------------------------------------------------------------------
\1\ Thallium is identified as a potential constituent of concern because
  it was detected in the totals analysis at levels exceeding the HBL and
  AWQC, and the SPLP filtrate analysis detection limit was too high to
  confirm that mobile levels of thallium do not exceed these standards.
  One half the detection limit was used as input to the risk assessment
  (see III.E.3).

How Was the Groundwater-to-Surface Water Risk Assessment Established?
    We assumed that surface impoundments present greater risks to the 
environment than tanks. Therefore we focused on the 3 facilities that 
manage wastewaters in impoundments. We selected the sampled facility 
for modeling because (1) its management practices (i.e., treatment in 
surface impoundments) are representative of 3 of the 4 chloride-only 
facilities, (2) the analytical data for this waste were obtained from 
this site, and (3) its setting is similar to the other 2 facilities 
that use surface impoundments. The facility selected for modeling is 
bounded on two sides by a river, tributary creeks, and swamps. The RCRA 
Facility Assessment \50\ for this site provides maps showing distances 
to these potential receptors and groundwater flow directions in the 
vicinity of the surface impoundments and plant-wide flow directions, 
with the overall flow being toward the river. We calculated 
infiltration rates for the unlined impoundment, and divided this flow 
rate into the flow rate of the river to determine potential 
concentrations of the five metals of concern in the river as a result 
of recharge with contaminated groundwater. The results of this 
screening (see ``Risk Assessment Support to the Inorganic Chemical 
Industry Listing: Background Information Document'') demonstrate that 
concentrations of the constituents of concern are likely to be well 
below risk thresholds for both human health and aquatic life in surface 
water.
---------------------------------------------------------------------------

    \50\ U.S. EPA RCRA Facility Assessment of Kerr McGee Chemical 
Corporation; Hamilton, MS. June 16, 1995.
---------------------------------------------------------------------------

How Was the Groundwater Ingestion Risk Assessment Established?
    We were able to collect specific information regarding the physical 
setting of the modeled facility, and thus used primarily site-specific 
data as input to the risk assessment. We chose this site for modeling 
because the amount of available information best supported our data 
requirements for modeling and because we believe this facility is 
representative of other generators of this waste category in terms of 
hydrogeological setting and waste characterization. Based on 
information presented in the RFA for the facility of concern, as well 
as from the U.S. Geological Survey Ground-water Site Inventory, there 
are groundwater wells north of the plant. The RFA also indicates that 
groundwater flow direction in the localized vicinity of the surface 
impoundments is to the northwest. We modeled the potential impact of 
the unlined portion of the surface impoundment train on drinking water 
wells located within 2,000-5,000 feet (based on well locations and the 
closest facility property lines). The resultant concentrations are 
presented below in Table III-41.

  Table III-41.--Groundwater Pathway Risk Assessment Results for Commingled Wastewaters From Chloride Process,
                                                Titanium Dioxide
----------------------------------------------------------------------------------------------------------------
                                                                            Risk or hazard quotient
                                                             ---------------------------------------------------
                   Constituent of concern                               90th%                     95th%
                                                             ---------------------------------------------------
                                                                 Adult        Child        Adult        Child
----------------------------------------------------------------------------------------------------------------
Antimony HQ.................................................          0.1          0.2          0.2          0.5
Arsenic cancer risk.........................................        2E-08        2E-08        8E-08        6E-08
Molybdenum HQ...............................................         0.03         0.07         0.06          0.1

[[Page 55753]]

 
Thallium HQ.................................................         0.02         0.03         0.03         0.07
----------------------------------------------------------------------------------------------------------------

What Is EPA's Listing Rationale for This Waste?
    We propose not to list commingled wastewaters from the production 
of titanium dioxide via the chloride process. The results of our risk 
assessment show that this waste category does not pose significant risk 
to human health and the environment. Our assessment of the air and 
surface water exposure pathways shows no risk of concern. Our 
assessment of the groundwater exposure pathway similarly shows no risk 
of concern for the constituents of concern.
    (2) Chloride process solids (Bevill exempt). Six facilities 
generate waste solids from the chloride process. As previously 
discussed, the Agency determined at 56 FR 27312 (June 13, 1991) that 
chloride process waste solids from titanium tetrachloride production 
are Bevill exempt mineral processing wastes (40 CFR 
261.4(b)(7)(ii)(S)). Five of the six facilities generate their solids 
in surface impoundments; the sixth, located in Louisiana, uses tank-
based settling to segregate the solids from their wastewaters. All six 
facilities dispose of their solids in their surface impoundments or on-
site landfills. Approximately 1.2 million MT of this waste was 
generated in 1998.\51\ The waste solids at each of these sites contains 
contributions from Bevill exempt solids ranging from 100% to 40%, as 
discussed further below.
---------------------------------------------------------------------------

    \51\ This waste volume includes the non-exempt sulfate solids 
generated at one of the 2 facilities that commingle wastes from the 
chloride and sulfate processes.
---------------------------------------------------------------------------

    At the two facilities located in Georgia and Louisiana, coke and 
ore solids are generated as entirely segregated wastes that are not 
commingled with non-exempt solids; these exempt wastes are clearly 
outside the scope of the consent decree dictating today's proposal and 
have not been assessed further.
    At three other facilities, the facilities conduct some commingling 
of their wastewaters, resulting in small potential contributions of 
non-exempt solids to their waste solids. Two of these facilities, both 
located in Ohio, commingle wastewaters from oxidation and finishing 
(i.e., generated after the production of titanium tetrachloride and 
therefore potentially bearing non-exempt solids) with the wastewaters 
from titanium tetrachloride production that bear exempt solids. Neither 
facility reported any solids in their oxidation and finishing 
wastewaters, although data from similar wastewaters from the chloride-
ilmenite process indicate that very low levels of solids can be present 
in similar wastewaters. (We assess solids from the chloride-ilmenite 
process in section III.F.14.e(10) of this proposal.) At the third 
facility (located in Mississippi), which operates a slightly different 
process, there were no reported wastewaters or solids from oxidation 
and finishing. Note that the wastewaters bearing the exempt solids at 
this facility are commingled with comparatively small volumes of 
wastewaters from sodium chlorate production (described in section 
III.F.11 of today's proposal).\52\ We believe that the contribution of 
any non-exempt solids to the volume of exempt solids from these three 
facilities would be very small. Thus, we have chosen not to attribute 
any risks to the nonexempt portion of these commingled solids.
---------------------------------------------------------------------------

    \52\ The sodium chlorate wastewaters account for only 1.7% of 
the total volume of managed wastewater, and for only 4.4% of the 
solids generated. The predominant potential constituent of concern 
in the sodium chlorate solids is chromium; analytical data for the 
commingled solids (KM-SI-04) show that the SPLP concentration is 
0.05 mg/L and not of concern. See section III.F.11 for further 
discussion of this facility's sludge.
---------------------------------------------------------------------------

    Two of the six facilities generating chloride process waste solids 
also operate sulfate-based titanium dioxide production lines. These 
plants are sited in Georgia and Maryland. Wastewaters from the chloride 
process and sulfate processes are commingled and results in commingled 
wastewater treatment solids that are partially composed of exempt 
solids. The non-exempt wastewater treatment solids are described 
separately in section III.F.14.e(8). They contain significant volumes 
of non-exempt solids (>35%).
    (3) Various sands from oxidation, milling and scouring.
How Many Facilities Generate This Waste Category and How Is It Managed?
    Two facilities using the chloride process reported disposal of 250 
MT of milling sand in off-site and dedicated on-site Subtitle D 
landfills. One facility also reported landfilling over 2,300 MT of 
scouring sand. One facility reported 6,935 MT/yr of waste oxidation 
sand that is managed in an on-site industrial Subtitle D landfill. All 
of these sands are similar and are associated with titanium dioxide 
finishing operations. All of these sands are produced after the 
beginning of chemical manufacturing and therefore are not exempt.
What Management Scenarios Were Assessed?
    We assessed the off-site industrial landfill scenario for milling 
sand and a dedicated on-site landfill for scouring sand, reflecting the 
types of management reported for these wastes. We assessed the 
groundwater ingestion pathway for these landfills. The on-site landfill 
scenario for scouring sand screened out when we compared the SPLP 
results for this waste directly to the HBLs.
How Was This Waste Category Characterized?
    We collected samples of both the milling sand and the scouring 
sand. We conducted total, TCLP and SPLP analyses on the waste matrix. 
We used the SPLP results (rather than the TCLP) to assess potential 
releases to groundwater because there is no contact with municipal 
landfill leachate in the reported management practices, and no 
indication that other practices are likely. The SPLP analytical results 
of concern for the milling sand are presented below in Table III-42.

[[Page 55754]]



  Table III-42.--Characterization of Milling Sand From Titanium Dioxide
                               Production
------------------------------------------------------------------------
                                                       Detected
                                                         SPLP
               Constituent of concern                 levels in  HBL (mg/
                                                       KP-SO-05     L)
                                                        (mg/L)
------------------------------------------------------------------------
Antimony............................................      0.024     0006
------------------------------------------------------------------------

How Was the Groundwater Ingestion Risk Assessment Established?
    As described in Section III.D.4. we used our standard distance-to-
well assumptions for an off-site landfill, and assumed hydrogeologic 
conditions would be comparable to those for the reported off-site 
landfill. As shown in Table III-43, the resultant risks were 
calculated.

 Table III-43.--Groundwater Pathway Risk Assessment Results for Milling
                  Sand From Titanium Dioxide Production
------------------------------------------------------------------------
                               Antimony HQ
-------------------------------------------------------------------------
                                                           Adult   Child
                       Percentile                          risk    risk
------------------------------------------------------------------------
90th....................................................   0.003   0.006
95th....................................................   0.008    0.02
------------------------------------------------------------------------

What is EPA's Listing Rationale for This Waste?
    We propose not to list this waste because the modeled and screening 
risk for antimony, the sole constituent of concern, is well below a 
hazard quotient of unity.
    (4) Gypsum from the sulfate process.
How Many Facilities Generate This Waste Category and How Is It Managed?
    The Maryland and Georgia facilities generate this waste. Both sites 
pipe their acid directly to their gypsum plants where it is neutralized 
to form gypsum. We found no significant potential for release of this 
acid waste prior to its treatment in the gypsum plant. The two 
facilities reported production of 69,500 MT/yr of gypsum that is 
landfilled.\53\ We chose to look further at this material because it is 
disposed of in a landfill and used in a manner constituting disposal 
(i.e., as fertilizer), and because the generators conduct on-site land 
placement (piles). Specifically, the Georgia facility places their 
gypsum in piles prior to sale for use in agricultural chemicals, 
cement, chemical products, and wall board. The Maryland facility 
generates primary and secondary gypsum, both of which are also placed 
in piles prior to use in wall board manufacture or disposal in an on-
site landfill. As described above, the gypsum is not an exempt mineral 
processing waste because this sulfate process wastestream did not meet 
the high volume/low toxicity criteria noted in 54 FR 36592 (September 
1, 1989).
---------------------------------------------------------------------------

    \53\ Additional volumes are used as products.
---------------------------------------------------------------------------

What Management Scenarios Were Assessed?
    We assessed each of the reported management scenarios that involve 
land placement: agricultural chemicals, cement, piles and landfills. We 
evaluated potential releases to both air and groundwater. Samples were 
collected at both facilities, and included both primary and secondary 
gypsum samples at the Maryland site. The management scenarios were 
assessed using the appropriate sample for the type of gypsum reported 
for that scenario. All pathways screened out except for the landfill 
scenario at the Maryland site. For the Maryland landfill we found 
constituent concentrations at levels of potential concern for the 
groundwater and surface water pathways. The primary gypsum contained 
lower levels of leachable metals than the secondary gypsum; we focused 
our modeling efforts on the higher volume secondary gypsum as it was 
more likely to show risk when modeled and the management scenarios are 
identical (they are placed in the same on-site industrial landfill). 
The screening results are discussed further in the ``Titanium Dioxide 
Listing Background Document for the Inorganic Chemical Listing 
Determination,'' available in the docket for today's notice.
    We assessed the landfill scenario for potential impacts to both 
surface water and drinking water wells. The facility selected for 
modeling is bounded to the north and east by the Patapsco River, which 
is an estuary. The expected groundwater flow, while not characterized 
definitively, is expected to be eastward, toward the river.\54\
---------------------------------------------------------------------------

    \54\ See ``Update of the Hazardous Waste Groundwater Task 
Force'', April 1998. Maryland Department of the Environment. RCRA 
Operation and Maintenance Inspection of SCM Chemicals (now 
Millennium Inorganic Chemicals, Inc.); Hawkins Point Plant; 
Baltimore, MD. October 1994.
---------------------------------------------------------------------------

How Was This Waste Category Characterized?
    We collected three samples of this waste for analysis. We conducted 
total, TCLP and SPLP analyses on the waste matrices. We used the SPLP 
results (rather than TCLP) to assess potential releases to groundwater 
and surface water because there is no contact with municipal landfill 
leachate in the reported management practices. We used total results to 
assess potential air releases, and this pathway screened out. The SPLP 
analytical results for the secondary gypsum that we used to assess 
groundwater releases from landfilling are presented below in Table III-
44.

    Table III-44.--Characterization of Secondary Gypsum from Sulfate
                        Process, Titanium Dioxide
------------------------------------------------------------------------
                                     Detected
                                   SPLP levels                AWQC  (mg/
      Constituent of concern       in MI-SO-03  HBL  (mg/L)       L)
                                      (mg/L)
------------------------------------------------------------------------
Antimony.........................        0.055        0.006        0.014
Arsenic..........................       0.0035       0.0007     0.000018
Manganese........................          3.1         0.73         0.05
------------------------------------------------------------------------


[[Page 55755]]

How Was the Groundwater-to-Surface Water Risk Assessment Established?
    We calculated infiltration rates for the unlined landfill, and 
divided this flow rate into the flow rate of the river to determine 
potential concentrations of the three metals of concern (see Table III-
44) in the river as a result of recharge with contaminated groundwater. 
The results of this screening (available in the Risk Assessment 
Background Document) demonstrate that concentrations of the 
constituents of concern are expected to be well below risk thresholds 
for human health and aquatic life in surface water.
How Was the Groundwater Ingestion Risk Assessment Established?
    While we are not aware of any actual drinking water wells in the 
vicinity of the Maryland facility, we were unable to determine 
definitively that there are not private wells in use in the residential 
area to the south of the facility, or that potentially contaminated 
groundwater would not reach this neighborhood. We thus decided to model 
potential exposure at this neighborhood. We modeled the potential 
impact of the unlined landfill on drinking water wells located within 
2,500-5,000 feet (based on distances to the nearest residential area). 
The resultant risks were calculated and are summarized in Table III-45.

 Table III-45.--Groundwater Pathway Risk Assessment Results for Secondary Gypsum from Sulfate Process, Titanium
                                                     Dioxide
----------------------------------------------------------------------------------------------------------------
                                      Antimony HQ            Arsenic--cancer risk            Manganese HQ
                             -----------------------------------------------------------------------------------
                               Adult risk    Child risk    Adult risk    Child risk    Adult risk    Child risk
----------------------------------------------------------------------------------------------------------------
90th........................         0.23          0.49        6.E-07        4.E-07           0.1           0.2
95th........................         0.35          0.75        1.E-06        1.E-06           0.1           0.3
----------------------------------------------------------------------------------------------------------------

What is EPA's Listing Rationale for This Waste?
    We propose not to list gypsum from the sulfate process. The results 
of our risk assessment demonstrate that there is no significant risk 
associated with this material, and that it does not warrant control as 
a listed hazardous waste. At the 95th percentile, the risks for 
antimony (HQ=0.75) and arsenic (1E-6), approach levels at 
which EPA considers listing wastes (HQ=1.0 and cancer 
risk>10-6, respectively). We believe that our modeled 
exposure scenario, while plausible, contains a number of conservative 
assumptions that likely overstate these marginal risks. In particular, 
our assumptions regarding groundwater flow direction (i.e., that a 
contaminated plume from the landfill would flow to the south toward the 
nearest residences, rather than due west toward the river) and the use 
of groundwater for drinking water at these residences (records indicate 
this community uses public water) may overstate actual risks.
    (5) Digestion scrubber water from the sulfate process.
How Many Facilities Generate This Waste Category and How Is It Managed?
    The Maryland and Georgia facilities reported generation of 
digestion scrubber water from the sulfate process. The Maryland 
facility manages this wastewater in a dedicated surface impoundment 
after neutralization. The other facility commingles this wastewater 
with other wastewaters from their chloride and sulfate processes. As 
described above, the gypsum is not an exempt mineral processing waste 
because this sulfate process wastestream did not meet the high volume/
low toxicity criteria noted in 54 FR 36592 (September 1, 1989). (See 40 
CFR 261.4(b)(7)(ii).)
What Management Scenarios Were Assessed?
    We assessed the waste in its commingled form as managed by the 
Maryland facility, as described below in section III.F.14.e(7). We also 
modeled the dedicated surface impoundment scenario using the physical 
parameters describing the dedicated Georgia impoundment. This 
impoundment is placed directly on the banks of a river, and thus we 
were primarily concerned with potential releases to surface water. We 
did not model a drinking water well scenario because there are no 
constituents of concern in this wastewater at levels exceeding HBLs.
How Was This Waste Category Characterized?
    We collected one sample of this waste for analysis. We conducted 
total analyses (leaching was not conducted given the low levels of 
percent solids in this waste), which are summarized below in Table III-
46 for the constituents of potential concern.

Table III-46.--Characterization of Digestion Scrubber Water from Sulfate
                        Process, Titanium Dioxide
------------------------------------------------------------------------
                                  Detected
                                levels in MI-
    Constituent of concern       WW-03  (mg/   HBL  (mg/L)  AWQC  (mg/L)
                                     L)
------------------------------------------------------------------------
Aluminum......................         0.58            16         0.087
Manganese.....................         0.58          0.73          0.05
Mercury.......................       0.0032         0.005      0.000050
------------------------------------------------------------------------

How Was the Groundwater-to-Surface Water Risk Assessment Established?
    We calculated infiltration rates for the unlined surface 
impoundment, and divided this flow rate into the flow rate of the river 
to determine potential concentrations of the three metals of concern 
(see Table III-46) in the river as a result of recharge with 
contaminated groundwater. The results of this screening (available in 
the Risk Assessment Background Document) demonstrate that 
concentrations of the constituents of concern are likely to be

[[Page 55756]]

well below risk thresholds for human health and aquatic life in surface 
water.
What is EPA's Listing Rationale for This Waste?
    We propose not to list digestion scrubber water from the production 
of titanium dioxide via the sulfate process. The results of our risk 
assessment show that this waste category does not warrant listing as a 
hazardous waste.
    (6) Sulfate process digestion sludges.
How Many Facilities Generate This Waste Category and How Is It Managed?
    The Maryland and Georgia facilities generate this sludge. The 
Georgia facility manages it in a dedicated surface impoundment and the 
Maryland facility places it in an on-site landfill. As described above, 
the waste is not an exempt mineral processing waste because this 
sulfate process wastestream did not meet the high volume/low toxicity 
criteria noted in 54 FR 36592 (September 1, 1989). (See 40 CFR 
261.4(b)(7)(ii).)
What Management Scenarios Were Assessed?
    We assessed both management scenarios using the respective samples 
collected at each facility. The surface impoundment scenario screened 
out; the levels of constituents in the wastewater were below HBLs and 
AWQC. We modeled the landfill scenario for potential releases to both 
groundwater drinking wells and surface water.
How Was This Waste Category Characterized?
    We collected one sample of this waste for analysis at the Maryland 
facility. We conducted total, TCLP, and SPLP analyses. We used the SPLP 
results as inputs to the on-site landfill, which are summarized below 
in Table III-47 for the constituents of potential concern.

    Table III-47.--Characterization of Digestion Sludge From Sulfate
                        Process, Titanium Dioxide
------------------------------------------------------------------------
                                  Detected
                                 SPLP Levels
    Constituent of concern       in MI-SO-02   HBL (mg/L)   AWQC  (mg/L)
                                   (mg/L)
------------------------------------------------------------------------
Aluminum......................          2.0            16         0.087
Antimony......................        0.023         0.006         0.014
Copper........................         0.37           1.3        0.0031
Iron..........................         12.0             5             1
Lead..........................    \1\ 0.004         0.015        0.0025
Manganese.....................         0.36          0.73          0.05
Vanadium......................         0.42          0.14
Zinc..........................         0.30           4.7         0.12
------------------------------------------------------------------------
\1\ Results are less than the typical laboratory reporting limit, but
  are greater than the calculated instrument detection limits.

How Was the Groundwater-to-Surface Water Risk Assessment Established?
    We calculated infiltration rates for the landfill, and divided this 
flow rate into the flow rate of the river to determine potential 
concentrations of the three metals of concern (see preceding table) in 
the river as a result of recharge with contaminated groundwater. Note 
that this is the same Maryland landfill described elsewhere in 
III.F.14.e(4) and (8). The results of this screening (available in the 
Risk Assessment Background Document) demonstrate that concentrations of 
the constituents of concern are likely to be well below risk thresholds 
for human health and aquatic life in surface water.
How Was the Groundwater Ingestion Risk Assessment Established?
    See the comparable discussion for the gypsum (III.F.14.e(4)). The 
groundwater ingestion scenario was assessed for antimony and vanadium 
because the detected SPLP concentrations exceeded their respective 
HBLs. We did not assess the iron HBL exceedence because the HBL is at 
or above the solubility limit in ground water under most conditions. 
The resultant risks were calculated and are summarized in Table III-48.

 Table III-48.--Groundwater Pathway Risk Assessment Results for Digestion Sludge From Sulfate Process, Titanium
                                                     Dioxide
----------------------------------------------------------------------------------------------------------------
                                                                     Antimony HQ               Vanadium HQ
                                                             ---------------------------------------------------
                                                               Adult risk   Child risk   Adult risk   Child risk
----------------------------------------------------------------------------------------------------------------
90th........................................................         0.13         0.27         0.02         0.03
95th........................................................         0.18         0.39         0.03         0.07
----------------------------------------------------------------------------------------------------------------

What Is EPA's Listing Rationale for This Waste?
    We propose not to list this waste. The results of our risk 
assessment modeling show that this waste does not contain mobile metals 
that are likely to pose risk to human health and the environment due to 
transport through the subsurface.
    (7) Commingled wastewaters from the chloride and sulfate process.
How Many Facilities Generate This Waste Category and How Is It Managed?
    The Maryland and Georgia facilities generate this waste category. 
Both facilities neutralized their commingled wastewaters and manage 
them in surface impoundments prior to NPDES discharge (but convey 
exempt solids into the wastewater treatment system where those solids 
are removed to form sludges that are comprised of exempt solids and 
non-exempt solids, depending on the specific piping of the plants).
What Management Scenarios Were Assessed?
    We collected samples at both facilities at the influent to their 
surface impoundment trains. We screened the

[[Page 55757]]

risk at both facilities using the analytical data describing their 
respective wastes. We concluded that the Georgia facility was not a 
modeling candidate because none of the constituents detected in its 
waste exceeded our health-based levels or the ambient water quality 
criteria. At the Maryland facility, we modeled the surface impoundment 
scenario using the physical parameters describing their unlined 
impoundment. We assessed both the surface water and drinking water well 
scenario.
How Was This Waste Category Characterized?
    The sample contained a high level of solids, reflecting the 
facility's practice of managing all waste solids and process 
wastewaters in the same unit. To isolate the impact of the wastewater 
on the environment from that of the sludge, we conducted the SPLP on 
the waste matrix, and separately analyzed the filtrate and the leachate 
generated from the leaching step. We are proposing to use the filtrate 
analysis as representative of the wastewater portion of the commingled 
waste matrix. The analytical results for the constituents found to be 
present in the filtrate at levels exceeding HBLs and/or AWQC are 
presented below in Table III-49.

  Table III-49.--Characterization of Commingled Wastewaters From Chloride and Sulfate Process, Titanium Dioxide
                                                     [mg/L]
----------------------------------------------------------------------------------------------------------------
                                                  Detected levels in sample  MI-
                                                               WW-04
             Constituent of concern              --------------------------------       HBL            AWQC
                                                       Total       SPLP Filtrate
----------------------------------------------------------------------------------------------------------------
Arsenic.........................................           0.022       0.005 (1)          0.0007        0.000018
Manganese.......................................             119            9.95            0.73            0.05
Thallium........................................           0.005           0.004           0.001         0.0017
----------------------------------------------------------------------------------------------------------------
(1) 1/2 the detection limit was used as input to the risk assessment.

How Was the Groundwater-to-Surface Water Risk Assessment Established?
    We calculated infiltration rates for the surface impoundment, and 
divided this flow rate into the flow rate of the river to determine 
potential concentrations of the two metals of concern (see preceding 
table) in the river as a result of recharge with contaminated 
groundwater. The results of this screening (available in the Risk 
Assessment Background Document) demonstrate that concentrations of the 
constituents of concern are likely to be well below risk thresholds for 
human health and aquatic life in surface water.
How Was the Groundwater Ingestion Risk Assessment Established?
    See the comparable discussion for the gypsum (III.F.14.e(4)). The 
resultant risks were calculated and are summarized in Table III-50.

 Table III-50.--Groundwater Pathway Risk Assessment Results for Commingled Wastewaters From Chloride and Sulfate
                                           Processes, Titanium Dioxide
----------------------------------------------------------------------------------------------------------------
                                                                   90th percentile           95th percentile
                   Constituent of concern                    ---------------------------------------------------
                                                                 Adult        Child        Adult        Child
----------------------------------------------------------------------------------------------------------------
Arsenic cancer risk.........................................        5E-08        3E-08        2E-07        1E-07
Manganese HQ................................................        0.009         0.02         0.02         0.04
----------------------------------------------------------------------------------------------------------------

What Is EPA's Listing Rationale for This Waste?
    We propose not to list commingled wastewaters from the production 
of titanium dioxide from the chloride and sulfate processes. The 
results of our risk assessment demonstrate that this waste category 
does not pose risks warranting listing as hazardous waste. Arsenic 
levels at the receptor result in cancer risks well below 1E-06, and 
manganese levels at the receptor are similarly well below a hazard 
quotient of one.
    (8) Wastewater treatment sludges from commingled chloride-and 
sulfate-process wastewaters.
How Many Facilities Generate This Waste Category and How Is It Managed?
    Two facilities, sited in Georgia and Maryland, generate this waste 
category, and after de-watering, place their sludges in on-site 
landfills. Over 159,000 MT of this waste was generated in 1998.
What Is the Bevill Exemption Status of This Waste Category?
    As discussed above, the chloride process waste solids are exempt 
mineral processing wastes, to the extent that they are associated with 
the titanium tetrachloride process. Data provided by these two 
facilities, however, show that these waste contain at least 35% non-
exempt solids. Our quantitative assessment of the potential risk 
associated with these non-exempt solids is provided here.
    The wastewater treatment solids at the Maryland site are derived 
from at least four primary sources. Two residuals from the chloride 
process contribute exempt solids (i.e., solids slurry and scrubber 
water from the reaction area) as identified in 261.4(b)(7)(ii)(S) and 
discussed above in III.F.14.e(2). Two scrubber waters from the 
calcination \55\ and finishing portion of the sulfate process 
contribute non-exempt solids to the wastewater treatment solids 
(sulfate process wastes

[[Page 55758]]

are not exempt because, as described above, the sulfate process 
wastestreams did not meet the high volume/low toxicity criteria noted 
in 54 FR 36592 (September 1, 1989)). Additional potential sources of 
minor amounts of solids are other wastewaters that are treated in this 
facility's wastewater treatment system, including cooling water, 
stormwater, drainage water and landfill leachate. Based on the 
information reported in this facility's Sec. 3007 survey response, we 
estimate that their wastewater treatment solids are more than 35% non-
exempt.
---------------------------------------------------------------------------

    \55\ Although wastes from calcining are generally treated as 
Bevill exempt extraction/beneficiation wastes, wastes from titanium 
dioxide calcination are post-mineral processing, chemical 
manufacturing wastes. The Agency noted at 54 FR 36619, ``As 
discussed in the April NPRM, the Agency considers any operations 
following the initial [mineral] processing operation to be [mineral] 
processing operations, regardless of whether the activity was 
included on the list of RTC beneficiation activities or has 
traditionally been considered beneficiation.'' Therefore, since 
mineral processing ends and chemical manufacturing starts at the 
beginning of oxidation, and the calcining step occurs after 
oxidation, all wastes generated from the calcining step are non-
exempt wastes.
---------------------------------------------------------------------------

    The wastewater treatment solids at the Georgia site are derived 
from at least six sources. Two residuals from the chloride process 
contribute exempt solids (i.e., waste acid from the chloride reaction 
area and supernatant from the chloride solids impoundment) 
(261.4(b)(7)(ii)(S)). Finishing wastewaters from the chloride process 
contribute non-exempt solids (these wastewaters are generated from the 
chemical manufacturing end of the production process). At least three 
wastewaters from the sulfate process contribute non-exempt solids. 
Based on the information reported in this facility's Sec. 3007 survey 
response, we estimate that their wastewater treatment solids are 
significantly more than 35% non-exempt.
What Management Scenarios Were Assessed?
    We collected samples of both facilities' wastes and therefore 
assessed the management practices at the two sites individually. The 
Maryland facility treats its wastewater in surface impoundments; the 
sludge is generated from a filter press, and the facility then places 
the sludge in an on-site landfill. We assessed potential groundwater 
releases to both surface water and drinking water wells from this 
landfill. The Georgia facility dredges its sludge from its surface 
impoundments, filter presses the solids, places the filter solids in 
piles for further drainage and air drying, and then places the filter 
solids in an industrial on-site landfill. We assessed the groundwater 
pathways for the landfill and pile, and the air pathway for the pile. 
(Note that we elsewhere assess the groundwater impact of the Maryland 
surface impoundments using sampling data for the wastewater in that 
unit. See III.F.14.e(7)). All pathways for the Georgia facility 
screened out and are not discussed further in this notice (see the 
``Titanium Dioxide Listing Background Document for the Inorganic 
Chemical Listing Determination'' for details of this screening).
How Was This Waste Category Characterized?
    Both facilities were selected for sampling and analysis. Both 
samples were collected from filter cake discharge of the filter press. 
We conducted total, TCLP and SPLP analyses on the waste matrix. We used 
the SPLP results (rather than the TCLP) to assess potential releases to 
groundwater and surface water because there is no potential for contact 
with municipal landfill leachate in the reported management practices 
for these two facilities. Given the large waste quantities reported for 
this category, we believe it would be prohibitively expensive for off-
site disposal to occur. We used total results to assess potential air 
releases from the piles, and found no significant risks. The SPLP 
analytical results used to assess groundwater releases at the Maryland 
facility that generates commingled chloride/sulfate wastewater 
treatment sludge (as described in the previous paragraph) are presented 
below in Table III-51.

   Table III-51.--Characterization of Commingled Wastewater Treatment
      Sludges From Chloride and Sulfate Processes, Titanium Dioxide
------------------------------------------------------------------------
                                     Detected
                                   SPLP levels                AWQC  (mg/
      Constituent of concern       in MI-SO-01  HBL  (mg/L)       L)
                                      (mg/L)
------------------------------------------------------------------------
Aluminum.........................         0.24           16        0.087
Arsenic..........................  \1\ 0.00005       0.0007     0.000018
Manganese........................         2.63         0.73         0.05
Thallium.........................    \1\ 0.003        0.001      0.0017
------------------------------------------------------------------------
\1\ Estimated results are less than the typical laboratory reporting
  limit, but are greater than the calculated instrument detection
  limits.

    In addition to the metals described above, our analytical data show 
that this waste contains polychlorinated dioxins and furans (PCDD/F). 
These data are provided in the background document for the titanium 
dioxide sector. As discussed previously (III.F.14.d), we believe that 
these contaminants are clearly associated with the exempt solids 
contained in this waste, and thus we did not assess them. Samples 
collected at these two facilities bear out this association with the 
exempt solids. The Maryland facility, which does not segregate any of 
its exempt solids from other wastewater treatment solids, has 
significantly higher PCDD/F levels than the Georgia facility (i.e., 
several orders of magnitude), which segregates the majority of its 
exempts solids from its wastewater treatment solids.
How Was the Groundwater-to-Surface Water Risk Assessment Established?
    The Maryland facility selected for modeling this scenario was also 
modeled for several other wastes, and is described further in section 
III.F.14.e(5) above. We calculated infiltration rates for the unlined 
landfill, and divided this flow rate into the flow rate of the river to 
determine potential concentrations of the four metals of concern (see 
preceding table) in the river as a result of recharge with contaminated 
groundwater. The results of this screening (available in the Risk 
Assessment Background Document) demonstrate that concentrations of the 
constituents of concern are likely to be well below risk thresholds in 
surface water.
How Was the Groundwater Ingestion Risk Assessment Established?
    The facility selected for modeling this scenario was also modeled 
for several other wastes, and is described further in section 
III.F.14.e(4) above. The resultant risks were calculated and are 
summarized in Table III-52.

[[Page 55759]]



   Table III-52.--Groundwater Pathway Risk Assessment Results for Commingled Wastewater Treatment Sludges From
                                Chloride and Sulfate Processes, Titanium Dioxide
----------------------------------------------------------------------------------------------------------------
                                                                  Manganese HQ                Thallium HQ
                                                         -------------------------------------------------------
                                                           Adult risk    Child risk    Adult risk    Child Risk
----------------------------------------------------------------------------------------------------------------
90th....................................................           0.1           0.3           0.1           0.3
95th....................................................           0.2           0.5           0.2           0.4
----------------------------------------------------------------------------------------------------------------

What Is EPA's Listing Rationale for This Waste?
    We are proposing not to list commingled wastewater treatment 
sludges from chloride and sulfate processes because our modeling of 
potential groundwater releases shows no risk at levels which warrant 
listing this waste as hazardous. No scenario modeled (groundwater-to-
surface water and groundwater-to-drinking water wells) showed risk at 
levels of regulatory concern.
    (9) Waste acid (ferric chloride) from the chloride-ilmenite 
process.
How Many Facilities Generate This Waste Category and How Is It Managed?
    All three facilities that utilize the chloride-ilmenite process 
generate this waste category. The DeLisle, Mississippi facility 
identifies the waste as characteristic for corrosivity, chromium and 
lead and disposes of its waste in an on-site underground injection 
well. The Tennessee facility pipes its ferric chloride to an on-site 
sodium chloride plant. Both the Mississippi and Tennessee facilities 
generate the majority of their exempt-mineral processing solids from 
the filtration of this waste acid. The Delaware facility's process is 
slightly different in that the majority of their exempt solids are 
generated prior to the generation of the waste acid, and only a 
relatively small portion of their solids are generated from the removal 
of solids from this waste. The Delaware facility adds a processing 
chemical to their waste acid, removes solids, stores the acid in tanks 
(as well as an on-site surface impoundment when their tank capacity is 
exceeded), and sells the acid to a broker for resale as a wastewater 
and drinking water treatment reagent. However, EPA is not at this time 
assessing whether the ferric chloride is a legitimate product. We did 
not attempt to address this complex and site-specific issue in this 
proposal. We note that the Delaware facility uses a surface impoundment 
to store a portion of the ferric chloride prior to its sale as a water 
and wastewater treatment reagent. EPA has often considered land-based 
units, and impoundments in particular, to be associated with the 
discard of wastes, rather than the storage of products, because of 
their potential for releases to the environment.\56\ In addition, we 
sampled the ferric chloride at the Delaware facility and found that it 
contains a variety of metals, as well as some chlorinated dioxins and 
furans. (See the background document for this sector for more details 
on this sampling and analysis). These factors may lead to concerns 
about the legitimacy of the use of this material as a drinking water 
and wastewater treatment reagent. However, as explained below, we do 
not need to resolve this issue to make a decision about listing ferric 
chloride.
---------------------------------------------------------------------------

    \56\ Surface impoundments pose essentially inherent risks of 
groundwater contamination due to the hydraulic pressure created by 
the contained liquids. Chemical Waste Management v. EPA, 919 F.2d 
158, 166 (D.C. Cir. 1992). Material that is placed in a surface 
impoundment, where it is capable of posing a substantial present or 
potential hazard to human health or the environment when improperly 
treated, stored, transported or disposed of or otherwise managed, 
``by leaching into the ground, is `discarded material' and hence a 
solid waste.'' (AMC II, 907 F.2d) Although secondary materials may 
have value and be reused, their value does not protect them from 
being considered solid wastes for the purposes of RCRA regulation if 
they are discarded prior to use (API, 906 F.2d at 741 n.16).
---------------------------------------------------------------------------

    This waste routinely exhibits the characteristic of corrosivity and 
the toxicity characteristic for chromium and lead. All three generators 
of the ferric chloride waste acid acknowledge the hazardous nature of 
this waste. Each generator reported pH levels at 1 or less, and the one 
facility that disposes of this waste via deep well injection assigns 
three separate characteristic codes to this material. EPA sampled the 
ferric chloride at the Delaware facility, and both EPA and the facility 
analyzed the waste. The results showed that this material exhibits the 
characteristics of D001, D007, and D008.
What Is the Bevill Status of This Waste?
    Ferric chloride waste acid is a liquid mineral processing waste 
that did not meet the high volume/low toxicity criteria for determining 
eligibility for the Bevill exemption and therefore is not Bevill-exempt 
(see 63 FR 28601).
What Is the Bevill Status of Solids Removed From This Waste?
    Prior to disposal or reuse of their waste acids, both the 
Mississippi and Tennessee plants filter their waste acid to remove the 
exempt solids. At the Delaware site, however, the waste acid is 
processed via the addition of a chemical prior to solids removal. The 
purpose of the chemical addition is to modify the properties of the 
waste acid to enhance its value as a saleable potable water and 
wastewater treatment reagent.
    The addition of this chemical at the Delaware plant marks the end 
of titanium tetrachloride production (i.e., mineral processing) and the 
beginning of ferric chloride production (assuming ferric chloride is a 
legitimate product). Ferric chloride production can be considered 
either chemical manufacturing \57\ or an ancillary process.\58\ 
Consequently, as explained below in section III.F.14.e(10), solids 
removed from the ferric chloride at the Delaware plant are not Bevill-
exempt.
---------------------------------------------------------------------------

    \57\ 54 FR 36616, September 1, 1989.
    \58\ All wastes from ancillary activities are not uniquely 
associated with extraction/beneficiation and processing of ores and 
minerals (see 45 FR 76619, November 19, 1980, and 63 FR 28590, May 
26, 1998).
---------------------------------------------------------------------------

What Is EPA's Listing Rationale for This Waste?
    We are proposing to not list this waste and rely instead on the 
existing regulatory controls provided by the hazardous waste 
characteristics. Data from all three facilities clearly demonstrates 
that this waste exhibits several of the characteristics. At this time 
we have not determined whether any of the facilities are out of 
compliance. State and EPA authorities are examining these sites in 
detail for compliance with the existing regulations. Listing would not 
serve to better establish this jurisdiction.
    The Mississippi facility that injects this waste identifies the 
waste as hazardous and manages it as a hazardous waste under Subtitle C 
regulations. Within the context of this consent decree, we did not 
investigate in depth the Tennessee facility's use of this material in 
production of sodium

[[Page 55760]]

chloride (an inorganic chemical not identified as one of the 14 
products of concern in the consent decree) because there was no known 
exposure route associated with the management of the material prior to 
inserting it into a non-consent decree production process. As discussed 
previously, the Delaware facility stores the material in a surface 
impoundment. EPA can address concerns, if appropriate, by the use of 
enforcement, based on the existing characteristics associated with this 
material. In addition, the questions framed above about the potential 
legitimacy of this facility's use of ferric chloride as a product and 
its storage in a surface impoundment are equally relevant whether the 
ferric chloride is listed as a hazardous waste or is known to exhibit 
the characteristics of hazardous waste. Therefore we have decided to 
not list this waste as a hazardous waste and rely on the hazardous 
characteristics of the material for any necessary control.
    (10) Non-exempt nonwastewaters from the chloride-ilmenite process.
How Many Facilities Generate This Waste Category and How Is It Managed?
    All three chloride-ilmenite facilities generate wastes that contain 
commingled exempt and non-exempt components. Depending on the specific 
configuration of the individual plants, these wastes are composed to 
different degrees of exempt and non-exempt solids, as described further 
below.
    Solids are generated in several places in the chloride ilmenite 
process:

--Coke and ore solids are removed from the gaseous titanium 
tetrachloride product stream, quenched and neutralized. While the 
Agency believes this stream is largely exempt, we note that any 
contributions to this stream from the disposal of the vanadium waste is 
non-exempt.
--Solids are generated during wastewater treatment and are non-exempt 
to the extent they are generated from oxidation and finishing 
wastewaters.
--Coke and ore solids can also be generated from the removal of solids 
from waste acid. These residuals may contain a non-exempt portion if 
they are partially comprised of vanadium waste. These solids cannot be 
exempt if they are removed from the waste acid after the initiation of 
chemical manufacturing and/or ancillary operations.

    We assessed these various sources of non-exempt materials as one 
waste category because of the expected similarities among these 
materials and the commingled management practices used by these 
facilities. The total non-exempt portion of this waste category is 
approximately 10% with variations among the three sites. The specific 
sources of non-exempt materials for each of the three chloride-ilmenite 
facilities is described below.
    All three facilities generate non-exempt vanadium waste when they 
separate vanadium compounds from titanium tetrachloride. The facilities 
reinsert these materials into the reaction area. Titanium tetrachloride 
is recovered and maybe reused; however, the remainder of this waste is 
not reused and is incorporated into the unreacted coke and ore solids 
stream from the reaction area, the solids separated from the ferric 
chloride, or the ferric chloride. This vanadium waste is not exempt 
because it is not a solid. However we were not able to determine the 
volume contribution of this vanadium waste to the various wastes into 
which it is ultimately incorporated. Hence, the estimates of total 
exempt solids provided below are likely to be underestimated. (This 
waste is also discussed in III.F.14.e(14) below.)
    The Delaware facility combines and neutralizes three sources of 
solids (reactor solids, solids removed from ferric chloride waste acid, 
and solids from wastewater treatment), and markets the resulting 
material as ``Iron Rich'' material. As asserted by the company, uses of 
Iron Rich include structural fill, landfill caps and covers, and 
construction of dikes for containment of dredged spoils on the Delaware 
River. The facility may also stabilize some portion of the Iron Rich 
with fly ash prior to sale. Each component of the Delaware commingled 
residuals is described in the following paragraphs.
    The majority of the commingled Delaware solids are unreacted coke 
and ore materials that are removed from the gaseous titanium 
tetrachloride product stream after the reactor. These ``reactor 
solids'' make up more than 80% of the volume of commingled ``Iron 
Rich'' at this facility. This stream is comprised of exempt chloride 
process solids and non-exempt vanadium waste.
    The Delaware facility also removes solids from its ferric chloride. 
This solids removal step takes place after the facility incorporates a 
chemical additive into the ferric chloride. We have concluded that the 
use of this chemical constitutes chemical processing that is outside 
the scope of the Bevill exemption (see 54 FR 36592, September 1, 1989 
and previous waste acid discussion in III.F.14(e)(9)). In addition, 
this stream is partially derived from the Delaware facility's non-
exempt vanadium waste. These ferric chloride solids are not exempt. 
They make up approximately 10% of the commingled ``Iron Rich''.
    The Delaware facility also uses scrubbers at various points in its 
process. Some solids make their way into scrubber waters. When the 
facility treats these wastewaters, the solids precipitate and the 
resultant wastewater treatment solids are added to the two wastes 
described above to form ``Iron Rich''. Solids from the scrubber used to 
treat gasses from the titanium tetrachloride reactor are Bevill-exempt. 
Solids from scrubbers associated with oxidation and finishing (steps 
that take place after the formation of titanium tetrachloride) are not 
exempt. Based on facility data, we estimate that approximately 1.5% of 
the total volume of ``Iron Rich'' consists of non-exempt solids from 
wastewater treatment.
    The Tennessee facility generates solids from ferric chloride 
filtration and from wastewater treatment. The filter solids are exempt 
(261.4(b)(7)(ii)(S)) because such filtration simply removes exempt 
solids. Unlike the processing that occurs at the Delaware plant, no 
chemical manufacturing is taking place at this step at the Tennessee 
plant. The facility landfills these ferric chloride solids as a 
discrete wastestream; we do not assess this exempt waste further in 
this rule. This facility commingles wastewaters from both the titanium 
tetrachloride and titanium dioxide sides of the process, and the 
resultant wastewater treatment sludge is thus comprised of exempt and 
non-exempt sources. The Tennessee facility reported estimated percent 
solids data for most of their wastewaters. We reviewed these data and 
determined that a significant portion (74%) of the resultant sludge 
would be nonexempt (see Titanium Dioxide Listing Background Document 
for calculations). These nonexempt solids are within the scope of 
today's proposal. We sampled the commingled exempt and nonexempt waste 
and describe our assessment of this material in this section.
    The Mississippi facility also generates exempt solids from 
filtering ferric chloride prior to deep well injection. No chemical 
manufacturing occurs. These solids are placed in a dedicated on-site 
landfill, and are not assessed further in this rule. The facility also 
operates a wastewater treatment system which is similar to the 
Tennessee facility in that it commingles wastewaters from condensation 
and purification (associated with the titanium tetrachloride production 
process), as well as oxidation and finishing

[[Page 55761]]

(associated with the titanium dioxide production process). The 
commingled wastewaters are managed in on-site surface impoundments and 
the dredged solids from these units (comprised of exempt and nonexempt 
materials) are placed in an on-site landfill. The facility provided 
detailed information regarding the amounts of solids present in each of 
the wastewaters managed in this system, demonstrating that there is a 
small contribution (3%) of non-exempt solids (i.e., solids 
in wastewaters from oxidation and finishing) in the wastewater 
treatment sludge. We did not select this facility for site visits and 
thus did not sample this waste. We believe our sampling and modeling of 
the Tennessee and Delaware sites is an appropriate surrogate for this 
waste given the similar nature of the processes at the three facilities 
(with particular similarities between the wastewater treatment 
facilities at Mississippi and Tennessee). Furthermore, the percentages 
of non-exempt solids in the commingled wastes at the Tennessee and 
Delaware sites are higher than at the Mississippi site.
What Management Scenarios Were Assessed?
    The Delaware facility asserts that there are a variety of end uses 
for the Iron Rich. The predominant recent use has been for the 
construction of dikes to contain dredged river sediments at U.S. Army 
Corp of Engineer disposal sites in the vicinity of the titanium dioxide 
plant. We assessed this scenario as comparable to an industrial D 
landfill scenario. The Iron Rich has also been used as daily cover at a 
municipal landfill (demonstration project) and as final cover for a 
closed on-site landfill. These uses clearly constitute disposal. Other 
proposed uses include use as subsidence fill at a closed municipal 
landfill, structural fill by the local Port Authority, surcharge for 
road bed compaction, and construction of a wildlife refuge at the site 
of the closed on-site industrial landfill. These uses all involve 
placement on the ground and also appear to also be uses that constitute 
disposal (see 40 CFR 266.20). We chose to model risks for disposal in 
an off-site industrial D landfill because this seemed to fit the 
largest number of the varied potential disposal or land-based use 
scenarios. We believe the municipal landfill scenario is also relevant. 
Our assessment addresses the municipal scenario qualitatively. These 
scenarios were assessed for potential releases to drinking water wells 
and air releases. In addition, we modeled the on-site landfill at the 
Tennessee facility for potential releases to surface water.
How Was This Waste Category Characterized?
    We collected samples of this waste at the Tennessee and Delaware 
facilities. For the Tennessee facility, we collected the sample 
directly from a holding/dewatering pond where the dredged wastewater 
treatment solids are dewatered prior to landfilling on site. We 
collected the sample from the Delaware facility directly from the Iron 
Rich dewatering unit press; this sample consisted of commingled 
chlorinator solids, ferric chloride solids, and wastewater treatment 
solids. This material is sometimes mixed with fly ash prior to use; our 
sample was collected prior to fly ash addition. Both samples were 
analyzed for total, TCLP and SPLP constituent analyses. These data are 
summarized below in Table III-54 for the constituents of concern that 
were present in the wastes at levels exceeding the health-based levels 
and/or ambient water quality criteria.

                   Table III-54.--Characterization of Wastewater Treatment Solids From the Chloride-Ilmenite Process, Titanium Dioxide
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                        Detected levels, Delaware site    Detected levels,                   AWQC  (mg/L)         Soil
                                                      ---------------------------------    Tennessee site               ---------------------- screening
                Constituent of concern                                                 ---------------------- HBL  (mg/                          levels
                                                         Total    TCLP  (mg/ SPLP  (mg/   Total    SPLP  (mg/     L)       Human     Aquatic      (mg/
                                                        (mg/kg)       L)         L)      (mg/kg)       L)                  health      life      kg)\1\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Antimony.............................................        0.9  \2\ 0.021       0.02        0.7      0.021      0.006      0.014        n/a         32
Arsenic..............................................        2.2     0.0035  \2\ 0.001        2.8  \3\ 0.003     0.0007    1.8E-05       0.15        4.7
                                                                                                           5
Barium...............................................        178    \2\ 2.4       0.92       49.6       0.12        1.1        n/a        n/a       5600
Boron................................................         30        1.7       0.61       24.5       0.45        1.4        n/a        n/a      7,200
Lead.................................................        309  \2\ 0.032  \2\ 0.003       42.4  \2\ 0.002      0.015  .........     0.0025        400
                                                                                     2
Manganese............................................     10,600        252       16.3      2,890        1.5        0.7       0.05        n/a  \4\ 3,800
Nickel...............................................       91.8        0.5      0.005       59.8      0.007       0.31       0.61      0.052      1,600
Thallium.............................................        3.7       0.28      0.012        7.2     0.0022      0.001     0.0017        n/a        6.4
Vanadium.............................................        240  \2\ 0.000      0.005      1,060      0.005       0.14        n/a        n/a       720
                                                                          3
--------------------------------------------------------------------------------------------------------------------------------------------------------
n/a: not applicable.
\1\ Soil ingestion health-based levels.
\2\ Results are less than the typical laboratory reporting limit, but are greater than the calculated instrument detection limits.
\3\ One half the detection limit was used as model input.
\4\ The air characteristic level is 3,000 mg/kg at 25m and drops to 30,000 at 150m.


[[Page 55762]]

    In addition, our analytical data show that chlorinated dioxins and 
furans are present in these wastes. As discussed previously, we believe 
these compounds are associated with the exempt solids. However, the 
Delaware waste contains the ferric chloride solids; these solids have 
lost their exempt status because of the facility's chemical 
manufacturing/ancillary activities necessary for the production of 
ferric chloride for sale as a water and wastewater treatment reagent. 
As a result, we have considered the chlorinated dioxin and furan 
content of the waste as part of today's listing determination. The 
PCDD/PCDF analytical results for the Delaware site are summarized below 
(detected homologs only) in Table III-55.

 Table III-55.--Characterization of Wastewater Treatment Solids from the
   Chloride-Ilmenite Process, Titanium Dioxide Chlorinated Dibenzo-p-
                     Dioxins (CDD) and Furans (CDF)
------------------------------------------------------------------------
                                                                Total
                                                               Detected
                                                              levels in
                   Constituent of concern                      Delaware
                                                             waste  (ng/
                                                               kg, wet
                                                                basis)
------------------------------------------------------------------------
2378-TetraCDF..............................................         12.2
12378-PentaCDF.............................................         21.8
23478-PentaCDF.............................................         48.1
123478-HexaCDF.............................................          237
123678-HexaCDF.............................................          8.1
234678-HexaCDF.............................................          2.5
123789-HexaCDF.............................................          5.6
1234678-HeptaCDF...........................................          189
1234789-HeptaCDF...........................................          126
OctaCDF....................................................       24,000
OctaCDD....................................................         22.2
2378-TetraCDD Equivalent\1\................................        57.2
------------------------------------------------------------------------
\1\ 12378-TetraCDD equivalent calculated using the World Health
  Organization Toxic Equivalency Factors (WHO-TEF). Van den Berg, et al.
  1998. Toxic Equivalency Factors (TEFs) for PCBs, PCDDs, PCDFs for
  Human and Wildlife. Environmental Health Perspectives, v.106, n.12,
  pp. 775-792. December.

How Was the Groundwater-to-Surface Water Risk Assessment Established?
    The Tennessee facility is bounded to the west by the Tennessee 
River. The facility indicated that the overall groundwater flow is 
toward the river. There have been several projects to determine 
placement of down gradient monitoring wells for individual on-site 
landfill units. These borings indicate that the groundwater elevation 
declines to the northwest towards the river. In addition, a contract 
geologist familiar with the local hydrogeology has indicated that 
shallow groundwater flow will generally follow the natural topography. 
A ridgeline running north and south is located just east of the 
facility boundary. This ridge is approximately 200 feet higher in 
elevation than the elevation at the facility. Based on this topography, 
we expect that the groundwater flow direction is to the west towards 
the river. We calculated the concentrations in the river that would 
result from discharge of contaminated ground water by estimating the 
infiltration rate for the unlined landfill, and (given the area of the 
landfill) diluting the resulting leachate volume into the river under 
various design flow conditions. The results of this screening level 
analysis (available in the Risk Assessment Background Document) 
demonstrate that concentrations of the constituents of concern in the 
river are likely to be well below the national AWQC for human health 
and aquatic life for these constituents.
How Was the Groundwater Ingestion Risk Assessment Established?
    The Delaware facility reported actual or contemplated use of the 
Iron Rich at a variety of landfills and land placement usages in the 
general vicinity of the plant. We used our usual distance-to-well 
assumptions for an off-site landfill, and assumed hydrogeologic 
conditions that are representative of the principal soil and aquifer 
types present regionally (within a 100 mile radius) of the facility. 
The resultant risk assessment results are presented below in Table III-
56.

 Table III-56.--Groundwater Pathway Risk Assessment Results for Non-wastewaters From Chloride-Ilmenite Process,
                                                Titanium Dioxide
----------------------------------------------------------------------------------------------------------------
                                                                      Hazard quotient or cancer risk
                 Constituents of concern                 -------------------------------------------------------
                                                           90th% adult   90th% child   95th% adult   95th% child
----------------------------------------------------------------------------------------------------------------
Antimony................................................           0.2           0.5           0.4           0.8
Arsenic (cancer risk)...................................         3E-07         2E-07         1E-06         9E-07
Manganese...............................................           0.8           1.6           1.6           3.3
Thallium................................................           0.7           1.4           1.1           2.4
----------------------------------------------------------------------------------------------------------------

What Is EPA's Listing Rationale for This Waste?
    We propose to list as hazardous the non-exempt portion of the solid 
wastes generated from the production of titanium dioxide via the 
chloride-ilmenite process. This listing covers the non-exempt portions 
of the wastewater treatment solids generated at all three facilities, 
any non-exempt portions of the chlorinator solids (e.g., any mass 
derived from the vanadium wastes), and ferric chloride solids generated 
at the Delaware facility. To the extent that these listed materials 
remain commingled with solids that would otherwise be exempt, the 
entire commingled mass is subject to the listing (see 
Sec. 261.3(b)(2)). Our risk results indicate that metals in these 
materials leach at levels that may pose a risk to human health and the 
environment. Specifically, in the commingled wastes, the risks exceed 
an HQ of one for both manganese (3.3) and thallium (2.4) at the 95th 
percentile; the risks similarly exceed an HQ of one for both manganese 
(1.6) and thallium (1.4) at the 90th percentile.
    In addition, the management practices reported for this waste, 
particularly as reported for the Delaware site, are expected to provide 
less control than the scenario modeled (i.e., an industrial landfill). 
Potential future management practices include use at municipal 
landfills for interim and final cover, as well as subsidence fill at a 
closed municipal landfill. These scenarios, particularly the interim 
cover scenario, indicate that the waste may come in contact with 
municipal landfill leachate in the future, if not listed. The TCLP 
results for this waste indicate even

[[Page 55763]]

higher mobility of metals than those modeled for the industrial 
landfill scenario using the SPLP. The TCLP concentrations of manganese 
and thallium exceed the SPLP levels by factors of 15-fold and 23-fold, 
respectively. We expect, therefore, that HQs resulting from disposal in 
a landfill with municipal waste would likely be higher by an order of 
magnitude than the industrial landfill scenario we modeled.
    The modeling presented above uses the entire waste volume reported 
for the Delaware facility's Iron Rich. We used this volume because it 
corresponds to the sample that we collected of this material, and there 
is considerable uncertainty on the portion of the waste that would be 
Bevill exempt. (This uncertainty is related to the estimated nature of 
the solids contributions provided by the facilities and the variability 
reported between the facilities.) We conducted a supplemental analysis 
to determine how sensitive our modeling results are to changes in 
volume, in recognition that we are only proposing at this time to list 
approximately 10% of the current Iron Rich volume (the balance of the 
Delaware site's waste being exempt and outside the scope of today's 
listing determination). These results, presented below in Table III-57, 
show that the risks are somewhat sensitive to the volume modeled, but 
the risks are not reduced below EPA's HQ threshold of one for 
noncarcinogens. In other words, if the facility were to segregate all 
exempt solids from the materials being proposed for listing prior to 
disposal, the remaining volume could still pose risk to human health 
and the environment. Further, as noted above, based on the TCLP 
results, the manganese and thallium HQs would be an order of magnitude 
higher in a municipal landfill scenario.

  Table III-57.--Reduced Volume Analysis; Groundwater Pathway Risk Assessment Results for Non-wastewaters From
                                   Chloride-Ilmenite Process, Titanium Dioxide
----------------------------------------------------------------------------------------------------------------
                                                                      Hazard quotient or cancer risk
                 Constituents of concern                 -------------------------------------------------------
                                                          90th % adult  90th % child  95th % adult  95th % child
----------------------------------------------------------------------------------------------------------------
Antimony................................................           0.1           0.2           0.2           0.4
Arsenic.................................................          not modeled
Manganese...............................................           0.5           1.0           1.0           2.2
Thallium................................................           0.4           0.9           0.8           1.6
----------------------------------------------------------------------------------------------------------------

    This waste also contains 57 ppt TCDD equivalents. This 
concentration exceeds the background level in soils (8 ppt) and the 
soil ingestion HBL of 45 ppt\59\. We were not able to compare this 
concentration with a screening level from the Air Characteristics Study 
because the study did not establish levels for TCDD. While we did not 
conduct a risk assessment of the detected TCDD TEQ, the presence of 
TCDD equivalents in the wastes is an additional factor that supports a 
listing determination, particularly in light of the fact that the 
management practices reported by the facility were varied and, in many 
cases, would constitute releases to the circulating environment with a 
greater potential for a variety of exposure pathways than would occur 
from a well managed landfill.
---------------------------------------------------------------------------

    \59\ EPA is currently evaluating the health risks from 2,3,7,8-
TCDD and once the review process is completed, EPA may re-examine 
the soil ingestion HBL. See http://www.epa.gov.ncea.dioxin.htm for 
additional information.
---------------------------------------------------------------------------

    The proposed listing address all non-wastewaters that are not 
covered by the mineral processing waste exemption, and is not limited 
to non-exempt wastewater treatment solids. The listing therefore would 
cover non-exempt non-wastewaters from the removal of vanadium wastes 
from the product titanium tetrachloride stream that are currently 
returned to the reaction area and ultimately commingled with the exempt 
reactor solids or ferric chloride (these solids were part of the Iron 
Rich sample collected by EPA to support this listing determination). 
Similarly, at the Delaware facility, solids that collect in the ferric 
chloride product storage tanks and impoundments would be covered by the 
listing as these solids are ineligible for the mineral processing 
exemption (because they are generated after the initiation of chemical 
manufacturing and/or ancillary operations), they are comparable to the 
ferric chloride solids that are commingled in the Iron Rich, and they 
are derived to some degree from non-exempt vanadium materials. The 
proposed listing, therefore, reads:

K178  Non-wastewaters from the production of titanium dioxide by the 
chloride-ilmenite process. (T) [This listing does not apply to 
chloride process waste solids from titanium tetrachloride production 
exempt under section 261.4(b)(7)]

    We are also proposing to add manganese and thallium to Appendix VII 
to Part 261, which designates the hazardous constituents for which K178 
would be listed. In addition, we are proposing to add manganese to the 
list of hazardous constituents in Appendix VIII to Part 261. We believe 
the available studies clearly show that manganese has toxic effects on 
humans and other life forms.\60\
---------------------------------------------------------------------------

    \60\ See information in EPA's IRIS database, which may be found 
at http://www.epa.gov/iris, and ``Risk Assessment Support to the 
Listing Determinations for the Inorganic Chemical Manufacturing 
Wastes'' (August 2000) in the docket for today's rule.
---------------------------------------------------------------------------

    (11) HCl from reaction scrubber, chloride-ilmenite process. All 
three chloride-ilmenite facilities reported generating HCl from 
scrubbing reactor off-gasses. These wastes are stored in covered tanks 
with vent scrubbers and are re-used on site, predominantly as pH 
control in wastewater treatment systems. We assessed this waste as part 
of the following category, ``Commingled wastewaters from chloride-
ilmenite process''.
    (12) Commingled wastewaters from the chloride-ilmenite process.
How Many Facilities Generate This Waste Category and How Is It Managed?
    All three chloride-ilmenite facilities commingle their wastewaters 
and treat them on-site. The Delaware facility utilizes a tank-based 
system, with final NPDES discharge through an unlined cooling pond to 
the adjacent river. Both the Tennessee and Mississippi facilities 
utilized surface impoundment based wastewater treatment systems. These 
wastewaters are not Bevill-exempt (but convey exempt solids into the 
wastewater treatment system where those solids are removed to form 
sludges that are comprised of exempt solids and non-exempt solids, 
depending on the specific piping of the plants).

[[Page 55764]]

What Management Scenarios Were Assessed?
    We modeled the surface impoundment scenarios at both the Tennessee 
and Mississippi sites. (We assumed any releases from the unlined 
cooling pond at the Delaware facility would be intercepted by the 
river, and would be comparable in concentration, but much less volume 
than the actual NPDES discharge point.)
    At the Tennessee site, we assessed the potential releases from the 
impoundment system to the adjacent river. We do not believe any 
drinking water wells could possibly be impacted by these impoundments 
given their placement on the river banks and within the facility 
property. We sampled at this facility at the headworks to the 
impoundment train.
    We assessed the Mississippi facility's impact on both surface water 
and potential drinking water wells. The RFI \61\ for this site 
indicates that the local groundwater flow is generally toward the south 
and east. It is unclear what the patterns are off site and how these 
patterns might change seasonally, but the groundwater elevation maps 
included in the RFI indicated that the direction of groundwater flow 
does vary seasonally and that a shift to a more westerly direction may 
occur under some conditions. Information from the U.S. Geological 
Survey's Ground-water Site Inventory, available in the docket for 
today's proposal, shows numerous drinking water wells in the vicinity 
of the plant, both to the east and southwest. The facility also 
reported wells on their property which they believe are cross-gradient 
and, in some cases, unused. We chose to model the groundwater scenario 
because of potential impacts on these known wells. We also assessed the 
potential impact of the Mississippi facility's surface impoundments on 
surface water because the facility is bounded to the south by the Bay 
of St. Louis.
---------------------------------------------------------------------------

    \61\ Draft RCRA Facility Investigation Report; DuPont DeLisle, 
NS. December 7, 1999.
---------------------------------------------------------------------------

    We did not conduct sampling and analysis at the Mississippi 
facility. Our risk assessment inputs for this facility used the 
combined analytical data set for the Delaware and Tennessee facilities, 
which are sister plants of the Mississippi plant. We used the physical 
parameters for the Mississippi site to describe wastewater flows, 
surface impoundment sizes, and distances to potential receptors for 
this modeling.
How Was This Waste Category Characterized?
    The analytical results for the constituents found to be present in 
the wastewaters at levels exceeding HBLs and/or AWQC are presented 
below in Table III-58.

   Table III-58.--Characterization of Commingled Wastewaters From Chloride-Ilmenite Process, Titanium Dioxide
----------------------------------------------------------------------------------------------------------------
                                                     Detected        Detected
                                                     levels in       levels in                     AWQC--Aquatic
             Constituent of concern                  Delaware        Tennessee      HBL  (mg/L)    life  (mg/L)
                                                  sample  (mg/L)  sample  (mg/L)
----------------------------------------------------------------------------------------------------------------
Aluminum........................................            0.65             3.1              16           0.087
Copper..........................................            0.03           0.007             1.3          0.0031
Lead............................................           0.003          0.005B           0.015          0.0025
Manganese.......................................             3.3            3.34            0.73             N/A
Nickel..........................................           0.013           0.020             0.3           0.052
Thallium........................................           0.005           0.013           0.001             N/A
Vanadium........................................           0.018            0.63            0.14            N/A
----------------------------------------------------------------------------------------------------------------
 B: also detected in blank
 N/A: not available

How Was the Groundwater-to-Surface Water Risk Assessment Established?
    The Tennessee facility is bounded to the west by a river. As noted 
above, the facility indicated that the overall groundwater flow is 
toward the river. The Mississippi facility is bounded to the south by 
the Bay of St. Louis, which is fed by 2 rivers to the east and west of 
the plant. Additional details are available in the docket. We 
calculated the concentration in the river that would result from 
discharge of contaminated groundwater by estimating the infiltration 
rate for the unlined surface impoundment, and (given the area of the 
impoundment) diluting the resulting leachate volume into the river 
under various design flow conditions. The results of this screening 
level analysis (available in Risk Assessment Support to the Inorganic 
Chemical Industry Listing: Background Information Document'') 
demonstrate that concentrations of the constituents of concern in the 
river are likely to be well below the human health and aquatic life 
AWQC for these constituents.
How Was the Groundwater Ingestion Risk Assessment Established?
    Based on information presented in the RFI for the Mississippi 
facility, as well as from the U.S. Geological Survey Ground-water Site 
Inventory, there are groundwater wells to the east and southwest of the 
plant within 2,000-5,000 feet. We modeled the potential impact of the 
unlined surface impoundment train on drinking water wells located 
within this range. The results are presented below in Table III-59.

[[Page 55765]]



  Table III-59.--Groundwater Pathway Risk Assessment Results for Commingled Wastewaters From Chloride-Ilmenite
                                            Process, Titanium Dioxide
----------------------------------------------------------------------------------------------------------------
                                                                          Hazard quotient
             Constituent of concern              ---------------------------------------------------------------
                                                   90th % adult    90th % child    95th % adult    95th % child
----------------------------------------------------------------------------------------------------------------
Manganese.......................................          0.0002          0.0003          0.0003          0.0007
Thallium........................................           0.002           0.004           0.004           0.009
Vanadium........................................         0.00009          0.0002          0.0003          0.0006
----------------------------------------------------------------------------------------------------------------

What Is EPA's Listing Rationale for This Waste?
    We propose not to list commingled wastewaters from the production 
of titanium dioxide via the chloride-ilmenite process. The results of 
our risk assessment demonstrate that this waste category poses no risks 
that warrant listing as hazardous waste. The concentrations of the 
constituents of concern at the modeled exposure points are well below 
an HQ of one.
    (13) Additive vent filter solids from the chloride-ilmenite 
process. One facility reported production of vent filter solids from 
additive handling. This material is placed in an off-site industrial D 
landfill. Small amounts of this waste are generated (1 MT). This 
material is not Bevill exempt. Handling of this additive is an 
ancillary activity. All wastes from ancillary activities are not 
uniquely associated with extraction/beneficiation and processing of 
ores and minerals (see 45 FR 76619, November 19, 1980, and 63 FR 28590, 
May 26, 1998).
    Information from the facility indicates that a constituent of 
concern in this material is aluminum. The drinking water HBL for 
aluminum is higher than the solubility limit in ground water and, 
therefore, contamination of ground water is not likely to pose a 
significant risk to human health. Based on this fact, and the very 
small volume generated by one facility, we propose not to list this 
material as a hazardous waste.
    (14) Vanadium waste from the chloride-ilmenite and chloride 
process. Vanadium containing material is generated from the production 
of titanium dioxide via the chloride and the chloride-ilmenite 
processes. This is not an exempt mineral processing waste because it is 
not a solid (see also 63 FR 28602). This waste is generally returned to 
the reaction area where titanium tetrachloride is recovered and the 
remainder of the vanadium waste is incorporated into the mass of the 
unreacted coke and ore solids (i.e., the exempt solids) and/or the 
waste acid. There is no potential for exposure prior to mixing with the 
exempt waste or waste acid. We assessed the mixtures of exempt and non-
exempt wastes as discussed above in III.D.14.e(8) and (10). 
Specifically, we assessed the wastewater treatment solids at the 
Maryland facility, the Iron Rich material at the Delaware facility, and 
the waste acid.
    (15) Off-specification titanium dioxide product.
How Many Facilities Generate This Waste Category and How is it Managed?
    Two facilities reported generating this waste, although we believe 
that all titanium dioxide manufacturers may generate this waste at some 
time. The two reporting facilities both describe off-site Subtitle D 
landfills that accept both municipal and industrial wastes as the final 
management practice for this waste. As noted in the September 1, 1989 
Bevill rulemaking, off-specification commercial product wastes are non-
exempt solid wastes.
What Management Scenarios Were Assessed?
    We modeled the off-site municipal D landfill scenario using the 
regional locations of the reported landfills.
How Was This Waste Category Characterized?
    We collected one sample of this waste and conducted totals, TCLP, 
and SPLP analyses. The analytical results for the one constituent found 
to be present in the waste TCLP sample at a level exceeding its HBL are 
presented below in Table III-60 (no constituent exceeded HBLs in the 
SPLP).

                  Table III-60.--Characterization of Off-specification Titanium Dioxide Product
----------------------------------------------------------------------------------------------------------------
                                                                  Detected levels in sample DPN-
                                                                           SO-02 (mg/L)
                     Constituent of concern                      --------------------------------   HBL  (mg/L)
                                                                       Total           TCLP
----------------------------------------------------------------------------------------------------------------
Lead............................................................             0.6        \1\ 0.06          0.015
----------------------------------------------------------------------------------------------------------------
 \1\ Results are less than the typical laboratory reporting limit, but are greater than the calculated
  instrument detection limits.

How Was the Groundwater Ingestion Risk Assessment Established?
    The facilities reported use of landfills in the vicinity of their 
plant. We used our usual distance-to-well assumptions for an off-site 
landfill, and assumed hydrogeologic conditions that are representative 
of the principal soil and aquifer types present regionally (within a 
100 mile radius) for the particular landfill sites that were reported 
for these wastes. The resultant groundwater concentrations were very 
low and are presented below in Table III-61.

        Table III-61.--Groundwater Pathway Risk Assessment Results for Off-specification Titanium Dioxide
----------------------------------------------------------------------------------------------------------------
                                                                   Predicted well concentrations
                                                                              (mg/L)
                     Constituent of concern                      --------------------------------   HBL  (mg/L)
                                                                       90th%           95th%
----------------------------------------------------------------------------------------------------------------
Lead............................................................         2.5E-08         1.1E-06           0.015
----------------------------------------------------------------------------------------------------------------


[[Page 55766]]

    The modeled levels of lead were so far below the HBL that we 
determined it was unnecessary to further assess the risks from lead. 
Clearly those risks would be well below an HQ of one.
What Is EPA's Listing Rationale for This Waste?
    We propose not to list off-specification titanium dioxide as a 
hazardous waste. Our risk analysis shows that this waste does not pose 
risks that warrant listing.
    (16) Railcar/trailer product washout. One facility reported 
generation of this residual (10,000 MT). The washwater, containing 
titanium dioxide, is placed in a surface impoundment. This waste is not 
Bevill exempt because it is a liquid and it is associated with the 
chemical manufacturing part of the process. The water from this pond is 
subsequently sent to wastewater treatment where it is commingled with 
all other chloride-ilmenite wastewaters (assessed in III.D.14.e(12)). 
The titanium dioxide product that settles to the bottom of this pond is 
mechanically recovered and returned to the production process. We 
assessed the potential impact of this impoundment via the SPLP 
analytical data collected for off-specification product (previously 
discussed in III.D.14.e(15)). These data are available in the 
background document for this sector, and show no constituents of 
concern. We chose the SPLP to assess this management scenario because 
there is no potential for contact with municipal landfill leachate. We 
therefore do not propose to list this waste.

G. What Is the Status of Landfill Leachate From Previously Disposed 
Wastes?

    Leachate derived from the treatment, storage, or disposal of listed 
hazardous wastes is classified as a hazardous waste by virtue of the 
``derived-from'' rule in 40 CFR 261.3(c)(2). The Agency has been clear 
in the past that hazardous waste listings apply to wastes disposed of 
prior to the effective date of a listing, even if the landfill ceases 
disposal of the waste when the waste becomes hazardous. (See 53 FR 
31147, August 17, 1988). We also have a well-established interpretation 
that listings apply to leachate derived from the disposal of listed 
hazardous wastes, including leachate derived from wastes meeting the 
listing description that were disposed before the effective date of a 
listing. We are not reopening any of these issues with this proposed 
rulemaking.
    Of course, as set out in detail in the August 1988 notice, this 
does not mean that landfills holding wastes that are listed now as 
hazardous become subject to Subtitle C regulation. However, previously 
disposed wastes now meeting a listing description, including residues 
such as leachate that are derived from such wastes, and that are 
managed actively do become subject to Subtitle C regulation. See 53 FR 
at 31149, August 17, 1988. In many, indeed most, circumstances, active 
management of leachate would be exempt from Subtitle C regulation 
because the usual pattern of management is discharge either to POTWs 
via the sewer system, where leachate mixes with domestic sewage and is 
excluded from RCRA jurisdiction (see RCRA Section 1004(27) and 40 CFR 
261.4(a)(1)), or to navigable waters, also excluded from RCRA 
jurisdiction (see RCRA Section 1004(27) and 40 CFR 261.4(a)(2)). In 
addition, management of leachate in wastewater treatment tanks prior to 
discharge under the CWA is exempt from RCRA regulation (40 CFR 
264.1(g)(6)).
    If actively managed, landfill leachate and gas condensate derived 
from the newly-listed wastes proposed for listing in today's proposal 
could be classified as K176, K177, or K178. In such circumstances, we 
would be concerned about the potential disruption in current leachate 
management that could occur, and the possibility of redundant 
regulation. This issue was raised to the Agency in the context of the 
petroleum refinery waste listings (see 63 FR 42173, August 6, 1998). A 
commenter expressed concern that, because some of the commenter's non-
hazardous waste landfills received newly-listed petroleum wastes prior 
to the effective date of the listing decision, the leachate that is 
collected and managed from these landfills would be classified as 
hazardous. The commenter argued that this could lead to vastly 
increased treatment and disposal costs without necessarily any 
environmental benefit. After examining and seeking comment on this 
issue, we published a final rule that temporarily defers regulation of 
landfill leachate and gas condensate derived from certain listed 
petroleum refining wastes (K169-K172) that were disposed before, but 
not after, the new listings became effective, provided certain 
conditions are met. See 64 FR 6806, February 11, 1999. Since then, we 
have published proposed rules for wastes from the dye and pigment 
industries (64 FR 40192, July 23, 1999) and the chlorinated aliphatics 
industry (64 FR 46476, August 25, 1998) that also propose deferrals for 
similar wastes derived from landfills.
    At the time this issue was brought to the Agency's attention in the 
context of the petroleum refinery waste listings, EPA's Office of Water 
had recently proposed national effluent limitations guidelines and 
pretreatment standards for wastewater discharges--most notably, 
leachate--from certain types of landfills. See 63 FR 6426, February 6, 
1998. In support of this proposal, EPA conducted a study of the volume 
and chemical composition of wastewaters generated by both subtitle C 
(hazardous waste) and subtitle D (non-hazardous waste) landfills, 
including treatment technologies and management practices currently in 
use. Most pertinent to finalizing the temporary deferral for the 
petroleum refining wastes, EPA did not propose (or subsequently 
finalize) pretreatment standards for subtitle D landfill wastewaters 
sent to POTWs because the Agency's information indicated that such 
standards were not required (see 65 FR 3008, January 19, 2000).
    The conditions included in the temporary deferral we published on 
February 11, 1999 are that the leachate is subject to regulation under 
the Clean Water Act, and the leachate cannot be stored in surface 
impoundments after February 13, 2001. See 40 CFR 261.4(b)(15). We 
believe that it was appropriate to temporarily defer the application of 
the new waste codes to such leachate in order to avoid disruption of 
ongoing leachate management activities while the Agency decides if any 
further integration is needed of the RCRA and CWA regulations 
consistent with RCRA Section 1006(b)(1). We believe that it is still 
appropriate to defer regulation and avoid leachate management 
activities, and to permit the Agency to decide whether any further 
integration of the two programs is needed. As such, we would be 
concerned about forcing pretreatment of leachate even though 
pretreatment is neither required by the CWA, nor needed. Therefore, we 
are proposing to temporarily defer the regulation of landfill leachate 
and gas condensate derived from the wastes we are proposing for listing 
in today's rule, with the same conditions as described in 40 CFR 
261.4(b)(15) for petroleum wastes. We seek comment on our proposed 
decision to extend the temporary deferral to include the wastes 
proposed for listing in today's notice.

[[Page 55767]]

IV. Proposed Treatment Standards Under RCRA's Land Disposal 
Restrictions

A. What Are EPA's Land Disposal Restrictions (LDRs)?

    RCRA requires us to establish treatment standards for all wastes 
destined for the land disposal. These are the ``land disposal 
restrictions'' or LDRs. For any hazardous waste identified or listed 
after November 8, 1984, we must promulgate these LDR treatment 
standards within six months of the date of identification or final 
listing (RCRA Section 3004(g)(4), 42 U.S.C. 6924(g)(4)). RCRA also 
requires us to set as these treatment standards ``* * * levels or 
methods of treatment, if any, which substantially diminish the toxicity 
of the waste or substantially reduce the likelihood of migration of 
hazardous constituents from the waste so that short-term and long-term 
threats to human health and the environment are minimized.'' (RCRA 
Section 3004(m)(1), 42 U.S.C. 6924(m)(1)).
    Once a hazardous waste is prohibited from land disposal, the 
statute provides only two options for legal land disposal: Meet the 
treatment standard for the waste prior to land disposal, or dispose of 
the waste in a land disposal unit that satisfies the statutory no 
migration test. A no migration unit is one from which there will be no 
migration of hazardous constituents for as long as the waste remains 
hazardous. RCRA sections 3004 (d), (e), (f), and (g)(5). Each waste 
identified for listing as hazardous in this rule will be subject to all 
the land disposal restrictions on the same day their respective listing 
becomes effective.
    We gathered data on waste characteristics and current management 
practices for wastes proposed to be listed in this action. These data 
can be found in the administrative record for this rule. An examination 
of the constituents that are the basis of the proposed listings shows 
that we have previously developed numerical treatment standards for 
most of the constituents. We have determined that it is technically 
feasible and justified to apply existing universal treatment standards 
(UTS) to the hazardous constituents in the wastes proposed to be listed 
as K176, K177, and K178 that were found to be present at concentrations 
exceeding the treatment standards, because the waste compositions are 
similar to other wastes for which applicable treatment technologies 
have been demonstrated. Also see LDR Phase II final rule, 59 FR 47982, 
September 19, 1994, for a further discussion of UTS. A list of the 
proposed regulated hazardous constituents and the proposed treatment 
limits can be found in the following preamble sections and in the 
proposed regulatory Table 268.40--Treatment Standards for Hazardous 
Wastes. If we make a final decision to list the identified wastes, 
these constituents and treatment standards would apply.
    We have provided in the BDAT background document a review of 
technologies that can be used to meet the proposed numerical 
concentration limits for K176, K177, and K178, assuming optimized 
design and operation. Where we are proposing numerical concentration 
limits, the use of other technologies capable of achieving the proposed 
treatment standards would be allowed, except for those treatment or 
reclamation practices constituting land disposal or impermissible 
dilution (see 40 CFR 268.3).

B. What Are the Treatment Standards for K176 (Baghouse Filters From 
Production of Antimony Oxide)?

    The constituents identified to require treatment in this waste are 
antimony, arsenic, cadmium, lead, and mercury. We are proposing to 
apply the UTS levels to these constituents as the treatment standards. 
Therefore, the nonwastewaters treatment standard proposed for antimony 
is 1.15mg/L TCLP; arsenic is 5.0 mg/L TCLP; cadmium is 0.11 mg/L TCLP; 
lead is 0.75 mg/L TCLP; and, mercury is 0.025 mg/L TCLP. In the event 
that there are wastewater treatment residuals from treatment of K176 
(which under the derived-from rule would also be considered as K176), 
the wastewater treatment standards are as follows: Antimony is 1.9 mg/
L; arsenic is 1.4 mg/L; cadmium is 0.69 mg/L; lead is 0.69 mg/L; and, 
mercury is 0.15 mg/L.
    We are requesting data and comment on the stabilization of 
antimony. Available stabilization data for antimony show effective 
treatment for wastes with initial antimony concentrations below those 
found in K176. Therefore, based on the available data, we are uncertain 
if stabilization will be effective for the antimony in this waste.

C. What Standards Are the Treatment Standards for K177 (Slag From the 
Production of Antimony Oxide That is Disposed of or Speculatively 
Accumulated)?

    The constituents identified to require treatment in this waste are 
antimony, arsenic, and lead. We are proposing to apply the UTS levels 
to these constituents as the treatment standards. Therefore, the 
nonwastewater treatment standard for antimony is 1.15 mg/L TCLP, for 
arsenic is 5.0 mg/L TCLP, and for lead is 0.75 mg/L TCLP. In the event 
that there are wastewater treatment residuals from treatment of K177 
(which under the derived-from rule also would be considered K177), the 
wastewater treatment standard for antimony is 1.9 mg/L, for arsenic is 
1.4 mg/L, and for lead is 0.69 mg/L.
    We are requesting data and comment on the stabilization of 
antimony. Available stabilization data for antimony show effective 
treatment for wastes with initial antimony concentrations below those 
found in K177. Therefore, based on the available data, we are uncertain 
if stabilization will be effective for the antimony in this waste.

D. What Are the Treatment Standards for K178 (Nonwastewaters From the 
Production of Titanium Dioxide by the Chloride-Ilmenite Process)?

    The constituents of concern in this waste are the chlorinated 
congeners of dibenzo-p-dioxin and dibenzofuran, thallium and manganese. 
We are proposing to apply the UTS levels to the chlorinated congeners 
of dibenzo-p-dioxin and dibenzofuran, and thallium, as indicated in 
Table V-1. In addition we are also proposing the option of complying 
with the technology standard of combustion (CMBST) for the chlorinated 
dibenzo-p-dioxin and dibenzofuran (dioxins and furans) constituents 
present in K178.
    We note at the outset that we typically promulgate numerical 
performance standards to allow facilities maximum flexibility in 
determining for themselves how best to achieve compliance with the LDR 
treatment standards. By promulgating combustion as an alternative 
compliance option, we are not disturbing the degree of flexibility 
afforded to facilities; rather, we are enhancing it.
    However, when we specify a treatment technology like CMBST as the 
treatment standard, the analytical elements of compliance change. 
Typically, with specified technologies, no testing and analysis of 
treatment residuals is required because we are confident that use of 
the specified technology will reduce the level of target organic 
constituents to levels that minimize threats to human health and the 
environment. For K178, the regulated organic constituents of concern 
are dioxin/furan congeners. If combustion in well designed and operated 
units is used to treat K178, the dioxin/furan congeners in the K178 
should be substantially destroyed. By

[[Page 55768]]

prescribing CMBST, we ensure that the units treating K178 will be units 
subject to the standards in Part 264 Subpart O or Part 266 Subpart H, 
or from interim status incinerators which have made a specific 
demonstration that they operate in a manner equivalent to a Part 264 or 
Part 266 combustion unit. The practical effect of this change will be 
to limit the type of facilities that can combust K178 to well-regulated 
RCRA units (or, after the current transition period, Clean Air Act 
permitted units subject to MACT standards). This will ensure that 
combustion is done in a closely-regulated facility and in a manner that 
provides protection for human health and the environment. Furthermore, 
by restricting combustion of K178 to these units, combustion will only 
occur in units subject to the recently upgraded dioxin/furan emission 
standards of the MACT Hazardous Waste Combustion Rule as well as 
standards for other hazardous air pollutants, such as metals (64 FR 
52828, September 30, 1999).
    K178 does have metal constituents of concern, which would not be 
treated by the combustion process and that would remain in the 
combustion treatment residuals (e.g., ash and scrubber water). We 
therefore are retaining metal treatment standards for all 
circumstances, i.e., whether or not the treatment used by a facility 
involves combustion. When combustion is used to treat the organics to 
achieve LDR compliance, facilities will still need to conduct 
compliance testing and analysis for all regulated metal constituents in 
the combustion treatment residuals prior to disposal. This approach is 
patterned after EPA's promulgation of a similar alternative treatment 
standard for F024 (wastes from production of chlorinated aliphatics) 
and also for F032 (wastes from wood preserving processes). See 55 FR 
22580-81, June 1, 1990. See also 62 FR 26000-3, May 12, 1997.
    For both solid and wastewater treatment residuals, we are proposing 
use of the Universal Treatment Standards (UTS) for all constituents of 
concern except manganese. Universal treatment standards have not been 
developed for manganese, although we are proposing standards below. We 
did not study this constituent in the development of F039 treatment 
standards in 1990 or UTS in 1994. Furthermore, we lack studies 
demonstrating treatment effectiveness for highly concentrated manganese 
nonwastewaters, such as those containing manganese at levels such as 
those found in K178. We did, however, identify treatability data for 
less concentrated manganese waste in our treatability database.
    These data show that solidification offers promising results in 
reducing the mobility of manganese, at least in less concentrated 
manganese waste. Such treatment yielded concentrations of 0.002, 0.003, 
and 0.46 mg/L TCLP. Under the LDR program, we typically apply a 
variability factor of 2.8 to the treated waste data, to account for 
variations arising from mechanical limitations in the treatment 
equipment. Therefore we calculated potential treatment standards based 
on solidification treatment from our treatability database as 0.006, 
0.008, and 1.29 mg/L TCLP. We are unsure whether these treatment 
standards would be achievable in a waste with the significantly higher 
concentrations of manganese found in K178. Therefore, we are not 
proposing treatment standards based on solidification. Rather, to 
propose a more achievable standard, we based it on a technology which 
results in higher post-treatment manganese levels. High temperature 
metals recovery (which vitrifies the manganese in the slag) resulted in 
a treated manganese concentration of 1.3 mg/L TCLP. Using this datum 
and our typical variability factor of 2.8, we calculated a proposed 
manganese treatment standard of 3.6 mg/L TCLP. We request comment and 
data on this proposed treatment standard, and we request anyone who has 
an interest in the treatment standard for manganese to comment to that 
effect. We may use the list of commenters on this topic as the only 
individuals notified of potential changes to this proposed treatment 
standard, so it is important for you to comment if you are in any way 
interested.
    Because it is possible that commenters may submit data showing that 
this treatment option is inappropriate for K178, we request comment on 
the option of setting a treatment standard for manganese that is 
identical to the current UTS level for thallium, the other metal found 
in proposed K178. The thallium treatment level of 0.20 mg/L TCLP is 
based on stabilization. We also request any information regarding the 
similarity of manganese nonwastewater treatment to the treatment of 
other RCRA-regulated metals that now appear in the UTS, both from a 
structural or physico-chemical perspective as well as from a treatment 
performance perspective.
    We have some treatment data for manganese in wastewater matrices 
derived from wastes other than K178 in our treatability database. It 
has been difficult to determine whether these treatment data are 
relevant because we have no examples of wastewaters derived from K178. 
We are therefore unsure if the wastes in our database are more or less 
concentrated than actual K178 wastewaters. To account for this 
uncertainty, we selected treatment data representing relatively high 
initial concentrations (up to 1000 mg/L), but also representing full 
scale operation and satisfactory treatment (at least 90 percent 
reduction in concentration). We found that sedimentation technology, 
the most effective treatment method in our database, resulted in a 
final effluent concentration of 6.1 mg/L and chemical precipitation 
technology resulted in final effluent concentrations of 2.4 and 4.8 mg/
L (both operated at full scale and resulted in greater than 90 percent 
reduction). We have selected, to be conservative, the highest 
concentration (6.1 mg/L) to calculate a K178 wastewater standard. We 
applied a variability factor of 2.8 to obtain a proposed K178 LDR 
treatment standard of 17.1mg/L. Again, we request comments on and data 
relevant to this proposed treatment standard for wastewater forms of 
K178, both from those who support the standard and those who believe 
the standard is not achievable. We also request any information 
regarding the similarity of manganese wastewater treatment to the 
treatment of other RCRA-regulated metals that now appear in the UTS, 
both from a structural or physico-chemical perspective as well as from 
a treatment performance perspective. Only commenters on this subject 
may be notified of future changes we may make based on newly submitted 
data.
    Because we typically include the same treatment standards for new 
listings into those for F039 (multisource leachate) to maintain 
equivalence within the LDR regulatory structure, we are also proposing 
to add the manganese treatment standard to the F039 section of the 
268.40 table. The F039 waste code applies to hazardous waste landfill 
leachates in lieu of the original waste codes when multiple waste codes 
would otherwise apply. F039 wastes are subject to numerical treatment 
standards equivalent to UTS. We are proposing this addition to the 
constituents regulated by F039 to maintain the implementation benefits 
of having one waste code for multisource leachate. We are also 
proposing to add manganese to the UTS Table at 40 CFR 268.48. Manganese 
represents significant risk to human health and the environment, as 
shown in the risk assessment accompanying this rule. Its presence in 
other hazardous wastes

[[Page 55769]]

should be mitigated by effective treatment to avoid similar risks after 
land disposal. Furthermore, when manganese is added to the UTS list, 
all characteristic wastes that have this constituent as an underlying 
hazardous constituent above the UTS levels will require treatment of 
manganese before land disposal. We solicit comments on these proposed 
conforming changes and especially on the impacts that they may have on 
other wastes beyond just K178.
    We request comment on the full set of proposed standards for K178 
listed in the following table.

                                    Table IV-1.--Treatment Standards for K178
----------------------------------------------------------------------------------------------------------------
            Regulated hazardous constituent                     Wastewaters                 Nonwastewaters
----------------------------------------------------------------------------------------------------------------
                                                                                       Concentration in mg/kg4
               Common name                  CAS1  No.     Concentration in mg/L 2,     unless noted as  ``mg/L
                                                            or technology code 3      TCLP'', or technology code
----------------------------------------------------------------------------------------------------------------
1,2,3,4,6,7,8-Heptachlorodibenzo-p-dioxin   35822-39-4  0.000035 or CMBST 5........  0.0025 or CMBST 5
1,2,3,4,6,7,8-Heptachlorodibenzofuran....   67562-39-4  0.000035 or CMBST 5........  0.0025 or CMBST 5
1,2,3,4,7,8,9-Heptachlorodibenzofuran....   55673-89-7  0.000035 or CMBST 5........  0.0025 or CMBST 5
HxCDDs (All Hexachlorodibenzo-p-dioxins).   34465-46-8  0.000063 or CMBST 5........  0.001 or CMBST 5
HxCDFs (All Hexachlorodibenzofurans).....   55684-94-1  0.000063 or CMBST 5........  0.001 or CMBST 5
1,2,3,4,6,7,8,9-Octachlorodibenzo-p-         3268-87-9  0.000063 or CMBST 5........  0.005 or CMBST 5
 dioxin (OCDD).
1,2,3,4,6,7,8,9-Octachlorodibenzofuran      39001-02-0  0.000063 or CMBST 5........  0.005 or CMBST 5
 (OCDF).
PeCDDs (All Pentachlorodibenzo-p-dioxins)   36088-22-9  0.000063 or CMBST 5........  0.001 or CMBST 5
PeCDFs (All Pentachlorodibenzofurans)....   30402-15-4  0.000035 or CMBST 5........  0.001 or CMBST 5
TCDDs (All tetrachlorodi-benzo-p-dioxins)   41903-57-5  0.000063 or CMBST 5........  0.001 or CMBST 5
TCDFs (All tetrachlorodibenzofurans).....   55722-27-5  0.000063 or CMBST 5........  0.001 or CMBST 5
Manganese................................    7439-96-5  17.1.......................  3.6 mg/L TCLP
Thallium.................................    7440-28-0  1.4........................  0.20 mg/L TCLP
----------------------------------------------------------------------------------------------------------------
1 CAS means Chemical Abstract Services. When the waste code and/or regulated constituents are described as a
  combination of a chemical with its salts and/or esters, the CAS number is given for the parent compound only.
2 Concentration standards for wastewaters are expressed in mg/L and are based on analysis of composite samples.
3 All treatment standards expressed as a Technology Code or combination of Technology Codes are explained in
  detail in 40 CFR 268.42 Table 1-Technology Codes and Descriptions of Technology-Based Standards.
4 Except for Metals (EP or TCLP) and Cyanides (Total and Amenable) the nonwastewater treatment standards
  expressed as a concentration were established, in part, based upon incineration in units operated in
  accordance with the technical requirements of 40 CFR part 264, subpart O or 40 CFR part 265, subpart O, or
  based upon combustion in fuel substitution units operating in accordance with applicable technical
  requirements. A facility may comply with these treatment standards according to provisions in 40 CFR
  268.40(d). All concentration standards for nonwastewaters are based on analysis of grab samples.
5 For these wastes, the definition of CMBST is limited to: (1) combustion units operating under 40 CFR 266, (2)
  combustion units permitted under 40 CFR Part 264, Subpart O, or (3) combustion units operating under 40 CFR
  265, Subpart O, which have obtained a determination of equivalent treatment under 268.42(b).

What Other LDR Provisions Are Proposed to Apply?
    1. Debris. We propose to apply the regulations at 40 CFR 268.45 to 
hazardous debris contaminated with K176, K177 or K178. Debris 
contaminated with these wastes would have to be treated prior to land 
disposal, using specific technologies from one or more of the following 
families of debris treatment technologies: extraction, destruction, or 
immobilization. Hazardous debris contaminated with a listed waste that 
is treated by an immobilization technology specified in 40 CFR 268.45 
Table 1 is a hazardous waste and must be managed in a hazardous waste 
facility. Residuals generated from the treatment of debris contaminated 
with K176, K177, or K178 would remain subject to the treatment 
standards proposed today. See 57 FR 37277, August 18, 1992, for 
additional information on the applicability, scope, and content of the 
hazardous debris provisions.
    2. Soil. In addition, we propose to apply the regulations at 40 CFR 
268.49 to hazardous soil contaminated with K176, K177, or K178. Soil 
contaminated with these wastes would have to be treated prior to land 
disposal, meeting either alternative treatment standards (i.e., 10 
times UTS or 90 percent reduction in initial constituent 
concentrations) or the standards at 40 CFR 268.40 being proposed today. 
Non-soil residuals generated from the treatment of soil contaminated 
with K176, K177, or K178 would remain subject to the treatment 
standards proposed today. See 63 FR 28602, May 26, 1998, for additional 
information on the applicability, scope, and content of the alternative 
soil treatment standard provisions.
    3. Underground Injection Wells that can be found in the 
administrative record for this rule. Finally, because land disposal 
also includes placement in injection wells (40 CFR 268.2(c)) 
application of the land disposal restrictions to K176, K177, and K178 
requires the modification of injection well requirements found in 40 
CFR 148. We propose that K176, K177, and K178 be prohibited from 
underground injection. Therefore, these wastes could not be underground 
injected unless they have been treated in compliance with the LDR 
treatment standards being proposed today, or if they are disposed in a 
deep injection well that has been granted a no migration petition for 
those wastes.

E. Is There Treatment Capacity for the Proposed Wastes?

1. What Is a Capacity Determination?
    EPA must determine whether adequate alternative treatment capacity 
exists nationally to manage the wastes subject to LDR treatment 
standards. RCRA section 3004 (h)(2). Thus, LDRs are effective when the 
new listings are effective (typically 6 months after the new listings 
are published in the Federal Register), unless EPA grants a national 
capacity variance from the otherwise-applicable date and establishes a 
different date (not to exceed two years beyond the statutory deadline) 
based on ``* * * the earliest date on which adequate alternative 
treatment, recovery, or disposal capacity which protects human health 
and the environment will be available'' (RCRA section 3004(h)(2), 42 
U.S.C.6924(h)(2)).
    Our capacity analysis methodology focuses on the amount of waste

[[Page 55770]]

currently disposed on the land, which will require alternative or 
additional treatment as a result of the LDRs. The quantity of wastes 
that is not disposed on the land, such as discharges regulated under 
NPDES, discharges to a POTW, or treatment in a RCRA-exempt tank, is not 
included in the quantities requiring additional treatment as a result 
of the LDRs. Also, land-disposed wastes that do not require alternative 
or additional treatment are excluded from the required capacity 
estimates (i.e., those that currently are treated to meet the LDR 
treatment standards). Land-disposed wastes requiring alternative or 
additional treatment or recovery capacity that is available on site or 
within the same company also are excluded from the required commercial 
capacity estimates. The resulting estimates of required commercial 
capacity then are compared to estimates of available commercial 
capacity. If adequate commercial capacity exists, the waste is 
restricted from further land disposal. If protective alternative 
capacity does not exist, EPA has the authority to grant a national 
capacity variance.
    In making the estimates described above, the volume of waste 
requiring treatment depends on the current waste management practices 
employed by the waste generators before this proposed regulation is 
promulgated and becomes effective. Data on waste management practices 
for these wastes were collected during the development of this proposed 
rule. However, we realize that as the regulatory process proceeds, 
generators of these wastes may decide to minimize or recycle their 
wastes or otherwise alter their management practices. Thus, we will 
monitor changes and update data on current management practices as 
these changes will affect the volume of wastes ultimately requiring 
commercial treatment or recovery capacity.
    The commercial hazardous waste treatment industry may change 
rapidly. For example, national commercial treatment capacity changes as 
new facilities come on line or old facilities go off line, and as new 
units and new technologies are added at existing facilities. The 
available capacity at commercial facilities also changes as facilities 
change their commercial status (e.g., changing from a fully commercial 
to a limited commercial or ``captive''--company owned--facility). Thus, 
we also continue to update and monitor changes in available commercial 
treatment capacity.
    For wastes required to meet today's proposed treatment standards, 
we request data on the annual generation volumes and characteristics of 
wastes affected by this proposed rule, including proposed hazardous 
wastes K176, K177, and K178 in wastewater and nonwastewater forms. We 
also request data on soil or debris contaminated with these wastes, 
residuals generated from the treatment or recycling of these wastes, 
and the current and planned management practices for the wastes, waste 
mixtures, and treatment residuals.
    For available capacity to meet the LDR requirements, we request 
data on the current treatment or recovery capacity capable of treating 
these wastes, facility and unit permit status related to treatment of 
the proposed wastes, and any plans that facilities may expand or reduce 
existing capacity or construct new capacity. In addition, we request 
information on the time and necessary procedures required for permit 
modification for generators or commercial treatment or disposal 
facilities to manage the wastes, required changes for operating 
practices due to the proposed listings or proposed additional 
constituent to be regulated in the wastes, and any waste minimization 
activities associated with the wastes. Of particular interest to us are 
chemical and physical constraints of treatment technologies for these 
wastes and any problems for disposing of these wastes. Also of interest 
are any analytical difficulties associated with identifying and 
monitoring the regulated constituents in these wastes.

F. What are the Capacity Analysis Results?

    This preamble only provides a summary of the capacity analysis 
performed to support this proposed regulation. For additional and more 
detailed information, please refer to the ``Background Document for 
Capacity Analysis for Land Disposal Restrictions: Inorganic Chemical 
Production Wastes (Proposed Rule),'' August 2000 (i.e., the Capacity 
Background Document).
    For this capacity analysis, we examined data on waste 
characteristics and management practices gathered for the inorganic 
chemical hazardous waste listing determinations. We also examined data 
on available treatment or recovery capacity for these wastes. The 
sources for these data are the RCRA Section 3007 Survey distributed in 
the spring of 1999, record sampling and site visits (see the docket for 
today's rule for more information on these survey instruments and 
facility activities), the available treatment capacity data submission 
that was collected in the mid-1990's, and the 1997 Biennial Report.
    For K176 and K177 wastes, the information from the surveys, 
sampling, and site visits indicates that there is no quantity of the 
wastewater form of K176 or K177 that is expected to be generated and 
therefore, there is no quantity of the wastewater form of K176 or K177 
that will require alternative commercial treatment. These wastes are 
typically present in a nonwastewater form. Based on the RCRA Sec. 3007 
Survey information presented in the Capacity Background Document, 
required alternative treatment capacity for K176 nonwastewaters is 
estimated to be eight tons per year. Required alternative treatment 
capacity for K177 nonwastewaters is estimated to be 22 tons per year. 
As described in the section of proposed LDR treatment standards above, 
we are proposing that numerical treatment standards be applied to K176 
and K177 nonwastewaters. We anticipate that commercially available 
stabilization, as well as other technologies, can be used in meeting 
these treatment standards. We estimate that the commercially available 
stabilization capacity is at least eight million tons per year based on 
the 1995 Biennial Report. Thus we expect there is sufficient capacity 
to treat the proposed K176 and K177 hazardous wastes that would require 
treatment. Therefore, we are proposing not to grant a national capacity 
variance for K176 or K177 wastewaters or nonwastewaters.
    For K178 waste (chloride-ilmenite nonexempt nonwastewaters from the 
production of titanium dioxide), our data indicate that the waste is 
typically generated as a nonwastewater. We did not identify any 
wastewater forms of these wastes and therefore do not anticipate that 
alternative management for wastewaters is required. We found that the 
wastes are currently land disposed. We estimated that approximately 
7,300 tons per year (derived from public information since data on 
amounts of treatment solids are confidential as reported in Sec. 3007 
Survey) may require alternative treatment. In our assessment, we 
assumed that facilities can segregate wastestreams and separately 
manage the newly-proposed hazardous waste. Although the generation 
quantity (and therefore, the quantity requiring treatment) may be 
higher due to the derived from rule, we expect that available treatment 
capacity still exists.
    As discussed earlier for K178 treatment standards, we are proposing 
that numerical treatment standards be applied to K178 wastes. We 
anticipate that commercially available incineration, followed by 
stabilization if

[[Page 55771]]

necessary, or high temperature metals recovery if applicable, can be 
used to meet these treatment standards. We also propose the technology 
standard of combustion (CMBST) as an alternative compliance option for 
hazardous organic constituents in the K178 wastes. The units treating 
the waste by using CMBST will be subject to certain standards, and 
facilities will need to meet treatment standards for all regulated 
metal constituents prior to disposal, as discussed in the earlier 
section on K178 treatment standards. We assume that facilities would 
achieve treatment standards using incineration, stabilization, or both. 
The quantity of commercially available combustion capacity for sludge 
and solid is a minimum of 300,000 tons per year and the quantity of 
commercially available stabilization capacity is at least eight million 
tons per year based on 1995 Biennial Report.
    We have identified that there exist facilities managing K178 waste 
in surface impoundments (i.e., in wastewater treatment systems that 
contain land based units). If the waste is managed in unretrofitted 
impoundments,\62\ it would thus be land disposed in a prohibited 
manner. These impoundments can be retrofitted, closed or replaced with 
tank systems. If the impoundment continues to be used to manage K178 
waste, the unit will be subject to Subtitle C requirements. In 
addition, any hazardous wastes managed in the affected impoundment 
after the effective date of today's rule are subject to land disposal 
prohibitions.\63\ However, facilities may continue to manage newly 
listed K178 in surface impoundments, provided they are in compliance 
with the appropriate standards for impoundments (40 CFR Parts 264 and 
265 subpart K) and the special rules regarding surface impoundments (40 
CFR 268.14). EPA notes that those provisions require basic groundwater 
monitoring (40 CFR Parts 264 and 265 Subpart F), management, and 
recordkeeping, but (in keeping with RCRA section 3005(j)(6)(A)) are 
afforded up to 48 months to retrofit to meet minimum technological 
requirements.
---------------------------------------------------------------------------

    \62\ A unretrofitted impoundment is one not satisfying the 
minimum technology requirements (MTR) specified in sections 3004(o) 
and 3005(j)(11).
    \63\ See RCRA Sec. 3004(m)(1) ``Simultaneously with the 
promulgation of regulations under subsection (d), (e), (f), or (g) 
prohibiting one or more methods of land disposal of a particular 
hazardous waste * * * promulgate regulations specifying those levels 
or methods of treatment * * *''
---------------------------------------------------------------------------

    Based on the foregoing, we expect that sufficient capacity to treat 
the proposed K178 hazardous wastes that would require treatment. 
Therefore, we are proposing not to grant a capacity variance for 
wastewater and nonwastewater forms of K178.
    With respect to the revisions to the F039 and UTS lists, as 
discussed earlier in the section on K178 treatment standards, we are 
proposing to add manganese to the list of regulated constituents in 
F039 (Sec. 268.40) and the UTS table (Sec. 268.48). We have estimated 
what portion of the F039 or characteristic wastes (which require 
treatment of underlying hazardous constituents to UTS levels) may be 
required to meet these new treatment standards. We request comments on 
the estimates, the appropriate means of treatment (if necessary), and 
the sufficiency of available treatment capacity for the affected wastes 
by the addition of manganese to the F039 and UTS lists.
    When changing the treatment requirements for wastes already subject 
to LDR (including F039 and characteristic wastes), EPA no longer has 
authority to use RCRA Sec. 3004(h)(2) to grant a capacity variance to 
these wastes. However, EPA is guided by the overall objective of 
section 3004(h), namely that treatment standards which best accomplish 
the goal of RCRA Sec. 3004(m) (to minimize threats posed by land 
disposal) should take effect as soon as possible, consistent with 
availability of treatment capacity.
    We expect that only a limited quantity of hazardous waste leachate 
may be generated from the disposal of newly-listed K176, K177, and K178 
wastes (due to the small number of generators) and added to the 
generation of leachates from other multiple restricted hazardous wastes 
already subject to LDR.
    For the amount of characteristic wastes or leachates generated from 
those previously regulated hazardous wastes that would be subject only 
to the new treatment standards for manganese, we evaluated the universe 
of wastes that might be impacted by revisions to the lists of regulated 
constituents for F039 and UTS based on limited information. Based on 
1997 Biennial Report data and some assumptions of waste compositions 
and their potential for land disposal, we were able to estimate the 
potential need for additional treatment. For example, we estimated an 
upper bound of 70,000 tons per year of nonwastewaters mixed with other 
waste codes, the F039 leachate from which would be potentially impacted 
by the revision to the F039 treatment standards. In a similar fashion, 
we estimated that no more than 520,000 tons per year of characteristic 
nonwastewaters potentially might be affected by the proposed changes 
(i.e., the addition of manganese to the F039 and UTS lists).
    These upper bound estimates are most likely very overstated since 
only a portion of each estimated waste volume may contain manganese at 
concentrations above the proposed level specified in the UTS table and 
the F039 list. The estimates assume that manganese is present at levels 
above the proposed treatment standards in all of these wastes and 
require alternative treatment, when it is likely that this may be true 
in only a small sets of the cases. Furthermore, EPA does not anticipate 
that waste volumes subject to treatment for F039 or characteristic 
wastes would significantly increase because waste generators already 
are required to comply with the treatment requirements for other metals 
that may be present in the wastes. The volumes of wastes for which 
additional treatment is needed solely due to the addition of manganese 
to the F039 and UTS lists are therefore expected to be very small. See 
the Capacity Background Document for detailed analysis.
    However, even though our volume estimates are highly conservative 
and overstated, we find that there still would be no shortage of 
treatment capacity. Based on data submittals in the mid-1990's and the 
1997 Biennial Report, EPA has estimated that approximately 37 million 
tons per year of commercial wastewater treatment capacity are 
available, and well over one million tons per year of liquid, sludge, 
and solid commercial combustion capacity are available. Also, as 
discussed earlier in this section, there exist several million tons of 
available stabilization capacity. These are well above the quantities 
of F039 or characteristic wastes potentially requiring treatment for 
manganese even under the conservative screening assumptions described 
above. Therefore, we are proposing a decision not to delay the 
effective date for adding manganese to the lists of constituents for 
F039 and UTS.
    We request comment on its proposed decision not to delay the 
effective date for adding manganese to the lists of constituents for 
F039 and UTS. We request data on the annual generation volumes and 
characteristics of wastes potentially affected by the proposed changes 
to UTS and F039 in wastewater and nonwastewater forms (if any), and the 
current and planned management practices for the wastes, waste 
mixtures, and treatment residuals. We also request data on the current 
treatment or recovery capacity capable of treating the affected wastes.

[[Page 55772]]

    Further, for soil and debris contaminated with the newly listed 
wastes (K176, K177, and K178), we believe that the vast majority of 
contaminated soil and debris contaminated with these wastes will be 
managed on-site and therefore will not require substantial commercial 
treatment capacity. Therefore, we are not proposing to grant a national 
capacity variance for hazardous soil and debris contaminated with these 
wastes covered under this proposal. Based on the 1999 RCRA Sec. 3007 
Survey followed by record sampling and site visits, there are no data 
showing the newly listed wastes managed by underground injection wells. 
Also, based on the 1999 RCRA Sec. 3007 Survey followed by record 
sampling and site visits, there are no data showing mixed radioactive 
wastes associated with the proposed listings. EPA is proposing to not 
grant a national capacity variance for underground injected wastes, 
mixed radioactive wastes, or soil and debris contaminated with these 
mixed radioactive wastes, if such wastes are generated.
    Therefore, we propose that LDR treatment standards for the affected 
wastes covered under today's rule thus become effective when the 
listing determinations become effective--the earliest possible date 
(see RCRA section 3004(h)(1)--land disposal prohibitions must take 
effect immediately when there is sufficient protective treatment 
capacity for the waste available). However, we may need to revise 
capacity analyses or capacity variance decisions if final listing 
determinations are changed or if we receive data and information to 
warrant any revision.
    Finally, we request comments on the estimated quantities requiring 
alternative treatment and information on characteristics of the 
affected wastes, management practices for these wastes, and available 
treatment, recovery or disposal capacity for the wastes. We also 
request comments concerning alternative management for any of these 
wastes managed in surface impoundments, including new piping or tank 
systems, and the length of time required for such activities. In 
addition, we solicit comments on our decision not to grant a national 
capacity variance or delay the effective date for any of the affected 
wastes. We will consider all available data and information provided 
during the public comment period and revise our capacity analysis 
accordingly in making the final capacity determinations. Please note, 
the ultimate volumes of wastes estimated to require alternative or 
additional commercial treatment may change if the final listing 
determinations change. Should this occur, we will revise the capacity 
analysis accordingly.

V. Compliance Dates

    We seek comment on the proposed decisions in this section.

A. Notification

    Under the RCRA Section 3010 any person generating, transporting, or 
managing a hazardous waste must notify EPA (or an authorized state) of 
its activities. Section 3010(a) allows us to waive, under certain 
circumstances, the notification requirement under Section 3010 of RCRA. 
If these hazardous waste listings are promulgated, we propose to waive 
the notification requirement as unnecessary for persons already 
identified within the hazardous waste management universe (i.e., 
persons who have an EPA identification number under 40 CFR 262.12). We 
do not propose to waive the notification requirement for waste handlers 
who have neither notified us that they may manage hazardous wastes nor 
received an EPA identification number. Such individuals will have to 
provide notification under RCRA Section 3010.

B. Interim Status and Permitted Facilities

    Because HSWA requirements are applicable in authorized states at 
the same time as in unauthorized states, we will regulate the newly 
identified wastes listed under HSWA until states are authorized to 
regulate these wastes. Thus, once this regulation becomes effective as 
a final rule, we will apply Federal regulations to these wastes and to 
their management in both authorized and unauthorized states.

VI. State Authority

A. Applicability of Rule in Authorized States

    Under Section 3006 of RCRA, we may authorize qualified states to 
administer and enforce the RCRA program within the state. (See 40 CFR 
Part 271 for the standards and requirements for authorization.) 
Following authorization, we retain enforcement authority under Sections 
3007, 3008, 3013, and 7003 of RCRA, although authorized states have 
primary enforcement responsibility.
    Before the Hazardous and Solid Waste Amendments of 1984 (HSWA) 
amended RCRA, a state with final authorization administered its 
hazardous waste program entirely in lieu of the Federal program in that 
state. The Federal requirements no longer applied in the authorized 
state, and we could not issue permits for any facilities located in the 
state with permitting authorization. When new, more stringent Federal 
requirements were promulgated or enacted, the state was obligated to 
enact equivalent authority within specified time-frames. New Federal 
requirements did not take effect in an authorized state until the state 
adopted the requirements as state law.
    By contrast, under Section 3006(g) of RCRA, 42 U.S.C. 6926(g), new 
requirements and prohibitions imposed by the HSWA (including the 
hazardous waste listings in this proposal) take effect in authorized 
states at the same time that they take effect in non-authorized states. 
EPA is directed to implement those requirements and prohibitions in 
authorized states, including the issuance of permits, until the state 
is granted authorization to do so. While states must still adopt HSWA-
related provisions as state law to retain final authorization, the 
Federal HSWA requirements apply in authorized states in the interim.

B. Effect on State Authorizations

    Because this proposal (with the exception of the actions proposed 
under CERCLA authority) will be promulgated pursuant to the HSWA, a 
state submitting a program modification is able to apply to receive 
either interim or final authorization under Section 3006(g)(2) or 
3006(b), respectively, on the basis of requirements that are 
substantially equivalent or equivalent to EPA's requirements. The 
procedures and schedule for state program modifications under 3006(b) 
are described in 40 CFR 271.21. It should be noted that all HSWA 
interim authorizations are currently scheduled to expire on January 1, 
2003 (see 57 FR 60129, February 18, 1992).
    Section 271.21(e)(2) of EPA's state authorization regulations (40 
CFR Part 271) requires that states with final authorization modify 
their programs to reflect federal program changes and submit the 
modifications to EPA for approval. The deadline by which the states 
must modify their programs to adopt this proposed regulation, if it is 
adopted as a final rule, will be determined by the date of promulgation 
of a final rule in accordance with 40 CFR 271.21(e)(2). If the proposal 
is adopted as a final rule, Table 1 at 40 CFR 271.1 will be amended 
accordingly. Once we approve the modification, the state requirements 
become RCRA Subtitle C requirements.
    States with authorized RCRA programs already may have regulations 
similar to those in this proposed rule. These state regulations have 
not been assessed against the Federal regulations being proposed to 
determine whether they meet the tests for authorization.

[[Page 55773]]

Thus, a state would not be authorized to implement these regulations as 
RCRA requirements until state program modifications are submitted to 
EPA and approved, pursuant to 40 CFR 271.21. Of course, States with 
existing regulations that are more stringent than or broader in scope 
than current Federal regulations may continue to administer and enforce 
their regulations as a matter of state law.
    It should be noted that authorized states are required to modify 
their programs only when EPA promulgates Federal standards that are 
more stringent or broader in scope than existing Federal standards. 
Section 3009 of RCRA allows states to impose standards more stringent 
than those in the Federal program. For those Federal program changes 
that are less stringent or reduce the scope of the Federal program, 
states are not required to modify their programs. See 40 CFR 271.1(I). 
This proposed rule, if finalized, is neither less stringent than nor a 
reduction in the scope or the current Federal program, and, therefore, 
states would be required to modify their programs to retain 
authorization to implement and enforce these regulations.

VII. Designation of Inorganic Chemical Wastes under the 
Comprehensive Environmental Response, Compensation, and Liability 
Act (CERCLA)

    All hazardous wastes listed under RCRA and codified in 40 CFR 
261.31 through 261.33, as well as any solid waste that is not excluded 
from regulation as a hazardous waste under 40 CFR 261.4(b) and that 
exhibits one or more of the characteristics of a RCRA hazardous waste 
(as defined in 40 CFR 261.21 through 261.24), are hazardous substances 
under the Comprehensive Environmental Response, Compensation, and 
Liability Act of 1980 (CERCLA), as amended (see CERCLA Section 
101(14)(C)). CERCLA hazardous substances are listed in Table 302.4 at 
40 CFR 302.4 along with their reportable quantities (RQs). If a 
hazardous substance is released in an amount that equals or exceeds its 
RQ, the release must be reported immediately to the National Response 
Center (NRC) pursuant to CERCLA Section 103.

A. Reporting Requirements

    Under CERCLA Section 103(a), the person in charge of a vessel or 
facility from which a hazardous substance has been released in a 
quantity that is equal to or exceeds its RQ must immediately notify the 
NRC as soon as that person has knowledge of the release. The toll-free 
telephone number of the NRC is 1-800-424-8802; in the Washington, DC, 
metropolitan area, the number is (202) 267-2675. In addition to this 
reporting requirement under CERCLA, Section 304 of the Emergency 
Planning and Community Right-to-Know Act of 1986 (EPCRA) requires 
owners or operators of certain facilities to report releases of 
extremely hazardous substances and CERCLA hazardous substances to State 
and local authorities. Immediately after the release of an RQ or more 
of an extremely hazardous substance or a CERCLA hazardous substance, 
EPCRA Section 304 notification must be given to the community emergency 
coordinator of the local emergency planning committee for any area 
likely to be affected by the release, and to the State emergency 
response commission of any State likely to be affected by the release.
    Under Section 102(b) of CERCLA, all hazardous substances (as 
defined by CERCLA Section 101(14)) have a statutory RQ of one pound, 
unless and until the RQ is adjusted by regulation. In today's proposed 
rule, we propose: (1) to list the following three wastestreams as RCRA 
hazardous wastes; (2) to designate these wastestreams as CERCLA 
hazardous substances, and (3) to adjust the one-pound statutory RQs for 
two of these wastestreams. The proposed wastestreams are as follows:

K176  Baghouse filters from the production of antimony oxide
K177 Slag from the production of antimony oxide that is disposed of 
or speculatively accumulated
K178 Nonwastewaters from the production of titanium dioxide by the 
chloride-ilmenite process. [This listing does not apply to chloride 
process waste solids from titanium tetrachloride production exempt 
under 40 CFR 261.4(b)(7).]

B. Basis for Proposed RQ Adjustment

    Our methodology for adjusting the RQs of individual hazardous 
substances begins with an evaluation of the intrinsic physical, 
chemical, and toxicological properties of each hazardous substance. The 
intrinsic properties examined--called ``primary criteria''--are aquatic 
toxicity, mammalian toxicity (oral, dermal, and inhalation), 
ignitability, reactivity, chronic toxicity, and potential 
carcinogenicity.
    Generally, for each intrinsic property, we rank the hazardous 
substance on a five-tier scale, associating a specific range of values 
on each scale with an RQ value of 1, 10, 100, 1,000, or 5,000 pounds. 
Based on the various primary criteria, the hazardous substance may 
receive several tentative RQ values. The lowest of the tentative RQs 
becomes the ``primary criteria RQ'' for that substance.
    After the primary criteria RQ is assigned, the substance is 
evaluated further for its susceptibility to certain degradative 
processes, which are used as secondary RQ adjustment criteria. These 
natural degradative processes are biodegradation, hydrolysis, and 
photolysis (BHP). If a hazardous substance, when released into the 
environment, degrades relatively rapidly to a less hazardous form by 
one or more of the BHP processes, its primary criteria RQ is generally 
raised one level. Conversely, if a hazardous substance degrades to a 
more hazardous product after its release, the original substance is 
assigned an RQ equal to the RQ for the more hazardous substance, which 
may be one or more levels lower than the RQ for the original substance.
    The standard methodology used to adjust the RQs for RCRA hazardous 
wastestreams differs from the methodology applied to individual 
hazardous substances. The procedure for assigning RQs to RCRA 
wastestreams is based on an analysis of the hazardous constituents of 
the wastestreams. The constituents of each RCRA hazardous wastestream 
are identified in 40 CFR part 261, Appendix VII. We determine an RQ for 
each constituent within the wastestream and establish the lowest RQ 
value of these constituents as the adjusted RQ for the wastestream.
    In today's proposed rule, we propose to assign a one-pound adjusted 
RQ to the K176 wastestream and 5,000 pounds to the K177 wastestream. 
The proposed adjusted RQs for both of these wastestreams are based on 
the lowest RQ value of the constituents present in each wastestream, 
are presented in Table VII-1 below. We seek comment our proposed 
adjustments to the RQ values for these wastes. We are not adjusting the 
RQ for K178 at this time because we have not yet developed a ``waste 
constituent RQ'' for manganese, one of the constituents of concern in 
this waste.

[[Page 55774]]



  Table VII-1.--Proposed Adjusted RQs for Wastestreams K176, K177, and
                                  K178
------------------------------------------------------------------------
                                                Wastestream
         Wastestream             Wastestream    constituent  Wastestream
                                 constituent     RQ  (lb.)    RQ  (lb.)
------------------------------------------------------------------------
K176.........................  arsenic........          1            1
                               lead...........         10    ...........
K177.........................  antimony.......      5,000        5,000
------------------------------------------------------------------------

VIII. Administrative Assessments

A. Executive Order 12866

    Under Executive Order 12866, [58 FR 51,735 (October 4, 1993)] the 
Agency must determine whether the regulatory action is ``significant'' 
and therefore subject to OMB review and the requirements of the 
Executive Order. The Order defines ``significant regulatory action'' as 
one that is likely to result in a rule that may: (1) Have an annual 
effect on the economy of $100 million or more or adversely affect in a 
material way the economy, a sector of the economy, productivity, 
competition, jobs, the environment, public health or safety, or State, 
local, or tribal governments or communities; (2) create a serious 
inconsistency or otherwise interfere with an action taken or planned by 
another agency; (3) materially alter the budgetary impact of 
entitlements, grants, user fees, or loan programs or the rights and 
obligations of recipients thereof; or (4) raise novel, legal or policy 
issues arising out of legal mandates, the President's priorities, or 
the principles set forth in the Executive Order.
    The Agency estimated the costs of today's proposed rule to 
determine if it is a significant regulation as defined by the Executive 
Order. The analysis considered compliance costs and economic impacts 
for inorganic chemical producers affected by this rule. We estimate the 
total cost of the rule to be $3 million annually. This analysis 
suggests that this rule is not economically significant according to 
the definition in E.O. 12866. The Office of Management and Budget has 
deemed this rule to be significant for novel policy reasons and has 
reviewed this rule.
    Detailed discussions of the methodology used for estimating the 
costs, economic impacts and the benefits attributable to today's 
proposed rule for listing hazardous wastes from inorganic chemical 
production, followed by a presentation of the cost, economic impact and 
benefit results, may be found in the background document: ``Economic 
Analysis of the Proposed Rule For Listing Hazardous Waste From 
Inorganic Chemical Production,'' which was placed in the docket for 
today's proposed rule. We seek comment on the methodology used, the 
projected economic impacts, and the benefits assumed for the proposed 
listings.
1. Methodology Section
    To estimate the cost, economic impacts to potentially affected 
firms and benefits to society from this proposed rulemaking, We 
evaluated Sec. 3007 Survey responses from inorganic chemical producers, 
firm financial reports, and chemical production data. The Agency has 
developed model facilities that represent composite information about 
inorganic chemical producers at both the facility and firm level. We 
also evaluated two scenarios. The first scenario evaluates the cost of 
listing all wastes that we propose to list in today's proposal. The 
second scenario includes not only wastes that EPA has proposed to list 
but also any waste that has exceeded risk screens (or other screening 
criteria) and had quantitative risk assessment completed. Analysis of 
these scenarios allows the public to understand what costs would have 
resulted from this rule making if all of the quantitative risk 
assessments involving fate and transport modeling had shown risk to 
human health.
    To estimate the incremental cost of this rule making, we reviewed 
baseline management practices and costs of potentially affected firms. 
Where more than one baseline management method was used (e.g. municipal 
incineration and landfilling), we either modeled more than one form of 
baseline management or selected the least expensive form of baseline 
management (which would overestimate rather than underestimate the cost 
of the rule).
    The Agency has modeled the most likely post-regulatory scenario 
resulting from the listing (e.g., disposal in a Subtitle C hazardous 
waste landfill, recycling) and estimated the cost of complying with it. 
The difference between the baseline management cost and the post-
regulatory cost is the incremental cost of the rulemaking.
    To estimate the economic impact of today's proposed rulemaking, we 
compared the incremental cost of the rulemaking with model firm sales 
and either net profit or product value. The Agency has also considered 
the ability of potentially affected firms to pass compliance costs on 
in the form of higher prices.
    To estimate the benefits of today's proposal, we evaluated risk 
assessment results and as well as a qualitative assessment of benefits 
including natural resource protection of groundwater.
2. Results
    a. Volume Results. Data reviewed by the Agency indicates that there 
are 9 inorganic chemical producers potentially affected by today's 
proposed rule. The data report that these firms generated 700,000 tons 
of inorganic chemical production waste annually that are potentially 
affected by today's proposed rule and modeled under Scenario 1. Data 
also indicate that there are 26 inorganic chemical producers who have 
generated wastes that are either being listed because they exhibit a 
characteristic or have been evaluated for quantitative risk assessment 
involving fate and transport modeling by the Agency to evaluate their 
potential effect on human health and the environment. These wastes are 
being modeled under Scenario 2.
    b. Cost Results. For today's proposed rule, we estimate the total 
annual incremental costs from today's proposal to be $ 2.5 million for 
all facilities. Sectors costs are summarized in Table 2.

[[Page 55775]]



                     Table VIII-1.--Estimated Incremental Cost By Inorganic Chemical Sector
----------------------------------------------------------------------------------------------------------------
                                   Estimated incremental annual costs $ 000s  (1999 $)     Number of affected
                                  -----------------------------------------------------        facilities
              Sector                                                                   -------------------------
                                           Scenario 1                Scenario 2          Scenario 1   Scenario 2
----------------------------------------------------------------------------------------------------------------
Antimony Oxide...................  1.6 (recycling), 35        1.6 (recycling), 35                 3            3
                                    (disposal).                (disposal).
Hydrogen Cyanide.................  .........................  215.....................            3            5
Sodium Chlorate..................  .........................  225.....................            0            5
Sodium Phosphate.................  .........................  76......................            0            4
Titanium Dioxide.................  2900.....................  6500....................            3            9
    Total........................  2937.....................  7051....................            9           26
                                  ------------------------------------------------------------------------------
----------------------------------------------------------------------------------------------------------------

    c. Economic Impact Results. To estimate potential economic impacts 
resulting from today's proposed rule, we used first order economic 
impacts measures such as the estimated incremental costs of today's 
proposed rule as a percentage of both affected firms' sales and 
estimated profits \64\. We applied these measures to affected inorganic 
chemical producers. For affected inorganic chemical producers in the 
antimony oxide and sodium chlorate sectors, we estimated the costs to 
be less than 3 percent of a typical firm's sales and less than 2 
percent of a firm's estimated profits. For affected inorganic chemical 
producers in the hydrogen cyanide sector, we estimated the cost to be 
less than 1 percent of a typical firm's sales and estimated profits. 
More detailed information on this estimate can be found in the economic 
analysis placed into today's docket.
---------------------------------------------------------------------------

    \64\ Because profit information is often either unavailable or 
more variable from year to year than sales measures, the Agency has 
chose to use a profit surrogate in completing the economic impact 
analysis of this proposal. According to Dun and Bradstreet's 
Industry Norms and Key Business Indicators (1995) the average net 
after tax profit for inorganic chemical producers in the 2819 SIC 
code was 6.3 percent. This percentage is applied to reported sales 
of affected firms in order to estimate their profits.
---------------------------------------------------------------------------

    d. Benefits Assessment. EPA has not conducted a quantitative 
assessment of actual benefits from this proposed rule. Because today's 
proposed rule results in new hazardous waste management requirements 
for K176, K177, and K178 wastes, the Agency believes that there may be 
a reduction in releases of hazardous constituents to the environment.

B. Regulatory Flexibility Act (RFA), as amended by the Small Business 
Regulatory Enforcement Fairness Act of 1996 (SBREFA), 5 USC 601 et. 
seq.

    The RFA generally requires an agency to prepare a regulatory 
flexibility analysis of any rule subject to notice and comment 
rulemaking requirements under the Administrative Procedures Act or any 
other statute unless the agency certifies that the rule will not have a 
significant economic impact on a substantial number of small entities. 
Small entities include small businesses, small organizations, and small 
governmental jurisdictions.
    For purposes of assessing the impacts of today's rule on small 
entities, a small entity is defined as: (1) A small business that has 
fewer than 1000 or 100 employees per firm depending upon the SIC code 
the firm primarily classified in \65\; (2) a small governmental 
jurisdiction that is a government of a city, county, town, school 
district or special district with a population of less than 50,000; and 
(3) a small organization that is any not-for-profit enterprise which is 
independently owned and operated and is not dominant in its field.
---------------------------------------------------------------------------

    \65\ The Small Business Administration has classified firms in 
the manufacturing sector (SIC Codes 20-39) and wholesale trade 
sector (SIC Codes 50-51) as small businesses within the sector based 
on the number of employees per firm. See Small Business Size 
Standards, 61 FR 3280, 3289 (January 31, 1996). Thus, to determine 
if a inorganic chemical producer is a small business, the primary 
SIC code of the firm would have to be determined. The small entities 
in today's rulemaking are in two SIC codes: (1) 2812 Alkalies and 
Chlorine, size standard 1000 employees and (2) 5082 Construction and 
Mining (except Petroleum) Machinery and Equipment size standard 100 
employees.
---------------------------------------------------------------------------

    After considering the economic impacts of today's proposed rule on 
small entities, I certify that this action will not have a significant 
economic impact on a substantial number of small entities.
    There are two potentially affected inorganic producing firms that 
constitute small entities. These firms are located in the antimony 
oxide sector. We have determined that these two firms would under this 
proposal incur costs of less than 1 percent of both the firm's sales 
and estimated profits under one scenario analyzed for the wastes in 
this sector. We continue to be interested in the potential impacts of 
the proposed rule on small entities and welcome comments on issues 
related to such impacts.

C. Paperwork Reduction Act

    The information collection requirements in this proposed rule have 
been submitted for approval to the Office of Management and Budget 
(OMB) under the Paperwork Reduction Act, 44 U.S.C. 3501 et seq. An 
Information Collection Request (ICR) document has been prepared (ICR 
No. 1968.01) and a copy may be obtained from Sandy Farmer by mail at 
Collection Strategies Division; U.S. Environmental Protection Agency 
(2822); 1200 Pennsylvania Ave., NW, Washington, DC 20460,by email at 
[email protected], or by calling (202) 260-2740. A copy may 
also be downloaded off the internet at http://www.epa.gov/icr.
    This rule is proposed under the authority of sections 3001(e)(2) 
and 3001(b)(1) of the Hazardous and Solid Waste Amendments (HSWA) of 
1984. The effect of listing the wastes described earlier will be to 
subject industry to management and treatment standards under the 
Resource Conservation and Recovery Act (RCRA).
    This proposed rule does not contain any new information collection 
requirements, nor does it propose to modify any existing information 
collection requirements. As a result, this proposed rule represents 
only an incremental increase in burden for generators and subsequent 
handlers of the newly listed wastes in complying with existing RCRA 
information collection requirements.
    The total annual respondent burden and cost for all existing 
paperwork associated with this proposed rule presented here represents 
the incremental increase in paperwork burden under six existing 
Information Collection Requests (ICRs). We estimate the total annual 
respondent burden for

[[Page 55776]]

all information collection activities to be approximately 417 hours, at 
an annual cost of approximately $19,916.
    Comments are requested on the Agency's need for this information, 
the accuracy of the provided burden estimates, and any suggested 
methods for minimizing respondent burden, including through the use of 
automated collection techniques. Send comments on the ICR to the 
Director, Collection Strategies Division; U.S. Environmental Protection 
Agency (2822); 1200 Pennsylvania Ave., NW, Washington, DC 20460; and to 
the Office of Information and Regulatory Affairs, Office of Management 
and Budget, 725 17th St., N.W., Washington, DC 20503, marked 
``Attention: Desk Officer for EPA.'' Include the ICR number in any 
correspondence. Since OMB is required to make a decision concerning the 
ICR between 30 and 60 days after September 14, 2000, a comment to OMB 
is best assured of having its full effect if OMB receives it by October 
16, 2000. The proposed rule will respond to any OMB or public comments 
on the information collection requirements contained in this proposal.

D. Unfunded Mandates Reform Act

    Title II of the Unfunded Mandates Reform Act of 1995 (UMRA), Public 
Law 104-4, establishes requirements for Federal agencies to assess the 
effects of their regulatory actions on State, local, and tribal 
governments and the private sector. Under section 202 of the UMRA, EPA 
generally must prepare a written statement, including a cost-benefit 
analysis, for proposed and final rules with ``Federal mandates'' that 
may result in expenditures to State, local, and tribal governments, in 
the aggregate, or to the private sector, of $100 million or more in any 
one year. Before promulgating an EPA rule for which a written statement 
is needed, section 205 of the UMRA generally requires EPA to identify 
and consider a reasonable number of regulatory alternatives and adopt 
the least costly, most cost-effective or least burdensome alternative 
that achieves the objectives of the rule. The provisions of section 205 
do not apply when they are inconsistent with applicable law. Moreover, 
section 205 allows EPA to adopt an alternative other than the least 
costly, most cost-effective or least burdensome alternative if the 
Administrator publishes with the proposed rule an explanation why that 
alternative was not adopted. Before EPA establishes any regulatory 
requirements that may significantly or uniquely affect small 
governments, including tribal governments, it must have developed under 
section 203 of the UMRA a small government agency plan. The plan must 
provide for notifying potentially affected small governments, enabling 
officials of affected small governments to have meaningful and timely 
input in the development of EPA regulatory proposals with significant 
Federal intergovernmental mandates, and informing, educating, and 
advising small governments on compliance with the regulatory 
requirements.
    Today's rule contains no Federal mandates (under the regulatory 
provisions of Title II of the UMRA) for State, local, or tribal 
governments or the private sector. The rule would not impose any 
federal intergovernmental mandate because it imposes no enforceable 
duty upon state, tribal or local governments. States, tribes and local 
governments would have no compliance costs under this rule. It is 
expected that states will adopt similar rules, and submit those rules 
for inclusion in their authorized RCRA programs, but they have no 
legally enforceable duty to do so. For the same reasons, we determined 
that this rule contains no regulatory requirements that might 
significantly or uniquely affect small governments. We have fulfilled 
the requirement for analysis under the Unfunded Mandates Reform Act.

E. Executive Order 12898: Environmental Justice

    EPA is committed to addressing environmental justice concerns and 
is assuming a leadership role in environmental justice initiatives to 
enhance environmental quality for all populations in the United States. 
The Agency's goals are to ensure that no segment of the population, 
regardless of race, color, national origin, or income bears 
disproportionately high and adverse human health or environmental 
impacts as a result of EPA's policies, programs, and activities, and 
that all people live in safe and healthful environments. In response to 
Executive Order 12898 and to concerns voiced by many groups outside the 
Agency, EPA's Office of Solid Waste and Emergency Response formed an 
Environmental Justice Task Force to analyze the array of environmental 
justice issues specific to waste programs and to develop an overall 
strategy to identify and address these issues (OSWER Directive No. 
9200.3-17).
    Today's proposed rule covers wastes from inorganic chemical 
production. It is not certain whether the environmental problems 
addressed by this rule could disproportionately affect minority or low-
income communities. Today's proposed rule is intended to reduce risks 
of hazardous wastes as proposed, and to benefit all populations. As 
such, this rule is not expected to cause any disproportionately high 
and adverse impacts to minority or low-income communities versus non-
minority or affluent communities.
    In making hazardous waste listing determinations, we base our 
evaluations of potential risk from the generation and management of 
solid wastes on an analysis of potential individual risk. In conducting 
risk evaluations, our goal is to estimate potential risk to any 
population of potentially exposed individuals (e.g., home gardeners, 
adult farmers, children of farmers, anglers) located in the vicinity of 
any generator or facility handling a waste. Therefore, we are not 
putting poor, rural, or minority populations at any disadvantage with 
regard to our evaluation of risk or with regard to how the Agency makes 
its proposed hazardous waste listing determinations.
    In proposing today to list wastes as hazardous (i.e., filter 
baghouses and low antimony slags from antimony oxide production that 
are discarded, nonexempt nonwastewater from the titanium dioxide 
chloride-ilmenite process,), all populations potentially exposed to 
these wastes or potentially exposed to releases of the hazardous 
constituents in the wastes will benefit from the proposed listing 
determination. In addition, listing determinations take effect at the 
national level. The wastes proposed to be listed as hazardous will be 
hazardous regardless of where they are generated and regardless of 
where they may be managed. Although the Agency understands that the 
proposed listing determinations, if finalized, may affect where these 
wastes are managed in the future (in that hazardous wastes must be 
managed at subtitle C facilities), the Agency's decision to list these 
wastes as hazardous is independent of any decisions regarding the 
location of waste generators and the siting of waste management 
facilities.
    Similarly, in cases where the Agency is proposing not list a solid 
waste as hazardous because the waste does not meet the criteria for 
being identified as a hazardous waste, these decisions are based upon 
an evaluation of potential individual risks located in proximity to any 
facility handling the waste. Therefore, any population living 
proximately to a facility that produces a solid waste that the Agency 
has proposed not to list would not be adversely affected either because 
the waste is already being managed as a hazardous waste in the Subtitle 
C system or because the solid waste does not pose a sufficient risk to 
the local population. We encourage all

[[Page 55777]]

stakeholders including members of the environmental justice community 
and members of the regulated community to provide comments or further 
information related to potential environmental justice concerns or 
impacts, including information and data on facilities that have 
evaluated potential ecological and human health impacts (taking into 
account subsistence patterns and sensitive populations) to minority or 
low-income communities.

F. Executive Order 13045: Protection of Children From Environmental 
Health Risks and Safety Risks

    Executive Order 13045, ``Protection of Children from Environmental 
Health Risks and Safety Risks'' (62 FR 19885, April 23, 1997), applies 
to any rule that: (1) is determined to be ``economically significant'' 
as defined under Executive Order 12866, and (2) concerns an 
environmental health or safety risk that EPA has reason to believe may 
have a disproportionate effect on children. If the regulatory action 
meets both criteria, the Agency must evaluate the environmental health 
or safety effects of the planned rule on children, and explain why the 
planned regulation is preferable to other potentially effective and 
reasonably feasible alternatives considered by the Agency. This 
proposed rule is not subject to the Executive Order because it is not 
economically significant as defined in E.O. 12866, and because the 
Agency does not have reason to believe the environmental health or 
safety risks addressed by this action present a disproportionate risk 
to children.
    The topic of environmental threats to children's health is growing 
in regulatory importance as scientists, policy makers, and village 
leaders continue to recognize the extent to which children are 
particularly vulnerable to environmental hazards. Recent EPA actions 
have been in the forefront of addressing environmental threats to the 
health and safety of children. Today's proposed rule further reflects 
our commitment to mitigating environmental threats to children.
    A few significant physiological characteristics are largely 
responsible for children's increased susceptibility to environmental 
hazards. First, children eat proportionately more food, drink 
proportionately more fluids, and breathe more air per pound of body 
weight than do adults. As a result, children potentially experience 
greater levels of exposure to environmental threats than do adults. 
Second, because children's bodies are still in the process of 
development, their immune systems, neurological systems, and other 
immature organs can be more easily and considerably affected by 
environmental hazards.
    Today's proposed rule is intended to avoid releases of hazardous 
constituents to the environment at levels that will cause unacceptable 
risks. We considered risks to children in our risk assessment. The more 
appropriate and safer management practices proposed in this rule are 
projected to reduce risks to children potentially exposed to the 
constituents of concern. The public is invited to submit or identify 
peer-reviewed studies and data, of which the agency may not be aware, 
that assess results of early life exposure to the proposed hazardous 
constituents from wastes from inorganic chemical production proposed 
for listing in today's rulemaking.

G. Executive Order 13084: Consultation and Coordination With Indian 
Tribal Governments

    Under Executive Order 13084, EPA may not issue a regulation that is 
not required by statute, that significantly or uniquely affects the 
communities of Indian tribal governments, and that imposes substantial 
direct compliance costs on those communities, unless the Federal 
government provides the funds necessary to pay the direct compliance 
costs incurred by the tribal governments, or EPA consults with those 
governments. If EPA complies by consulting, Executive Order 13084 
requires EPA to provide to the Office of Management and Budget, in a 
separately identified section of the preamble to the rule, a 
description of the extent of EPA's prior consultation with 
representatives of affected tribal governments, a summary of the nature 
of their concerns, and a statement supporting the need to issue the 
regulation. In addition, Executive Order 13084 requires EPA to develop 
an effective process permitting elected officials and other 
representatives of Indian tribal governments ``to provide meaningful 
and timely input in the development of regulatory policies on matters 
that significantly or uniquely affect their communities.''
    For the reasons described above, today's proposed rule does not 
create a mandate on State, local or tribal governments, nor does it 
impose any enforceable duties on these entities. Accordingly, the 
requirements of section 3(b) of Executive Order 13084 do not apply to 
this rule.

H. Executive Order 13132--Federalism

    Executive Order 13132, entitled ``Federalism'' (64 FR 43255, August 
10, 1999), requires EPA to develop an accountable process to ensure 
``meaningful and timely input by State and local officials in the 
development of regulatory policies that have federalism implications.'' 
``Policies that have federalism implications'' is defined in the 
Executive Order to include regulations that have ``substantial direct 
effects on the States, on the relationship between the national 
government and the States, or on the distribution of power and 
responsibilities among the various levels of government.''
    Under Section 6 of Executive Order 13132, EPA may not issue a 
regulation that has federalism implications, that imposes substantial 
direct compliance costs, and that is not required by statute, unless 
the Federal government provides the funds necessary to pay the direct 
compliance costs incurred by State and local governments, or EPA 
consults with State and local officials early in the process of 
developing the proposed regulation. EPA also may not issue a regulation 
that has federalism implications and that preempts State law, unless 
the Agency consults with State and local officials early in the process 
of developing the proposed regulation.
    Section 4 of the Executive Order contains additional requirements 
for rules that preempt State or local law, even if those rules do not 
have federalism implications (i.e., the rules will not have substantial 
direct effects on the States, on the relationship between the national 
government and the states, or on the distribution of power and 
responsibilities among the various levels of government). Those 
requirements include providing all affected State and local officials 
notice and an opportunity for appropriate participation in the 
development of the regulation. If the preemption is not based on 
express or implied statutory authority, EPA also must consult, to the 
extent practicable, with appropriate State and local officials 
regarding the conflict between State law and Federally protected 
interests within the agency's area of regulatory responsibility.
    This proposed rule does not have federalism implications. It will 
not have substantial direct effects on the States, on the relationship 
between the national government and the States, or on the distribution 
of power and responsibilities among the various levels of government, 
as specified in Executive Order 13132. This proposed rule directly 
affects primarily inorganic chemical producers. There are no State and 
local government bodies that incur direct compliance costs by this 
rulemaking. State and local government

[[Page 55778]]

implementation expenditures are expected to be less than $500,000 in 
any one year.\66\ Thus, the requirements of section 6 of the Executive 
Order do not apply to this rule.
---------------------------------------------------------------------------

    \66\ For more information, please refer to Appendix C of the 
background document ``Economic Analysis of the Proposed Rule For 
Listing Hazardous Waste From Inorganic Chemical Production,'' which 
was placed in the docket for today's proposed rule.
---------------------------------------------------------------------------

    This proposed rule would preempt State and local law that is less 
stringent for these inorganic chemical production wastes as hazardous 
wastes. Under the Resource Conservation and Recovery Act (RCRA), 42 
U.S.C. 6901 to 6992k, the relationship between the States and the 
national government with respect to hazardous waste management is 
established for authorized State hazardous waste programs, 42 U.S.C. 
6926 (3006), and retention of State authority, 42 U.S.C. 6929 (3009). 
Under section 3009 of RCRA, States and their political subdivisions may 
not impose requirements less stringent for hazardous waste management 
than the national government. By publishing and inviting comment on 
this proposed rule, we hereby provide State and local officials notice 
and an opportunity for appropriate participation. Thus, we have 
complied with the requirements of section 4 of the Executive Order.

I. National Technology Transfer and Advancement Act

    Section 12(d) of the National Technology Transfer and Advancement 
Act of 1995 (``NTTAA''), Public Law 104-113, section 12(d) (15 U.S.C. 
272 note) directs EPA to use voluntary consensus standards in its 
regulatory activities, unless to do so would be inconsistent with 
applicable law or otherwise impractical. Voluntary consensus standards 
are technical standards (e.g., materials specifications, test methods, 
sampling procedures, and business practices) that are developed or 
adopted by voluntary consensus standards bodies. The NTTAA directs EPA 
to provide Congress, through OMB, explanations when the Agency decides 
not to use available and applicable voluntary consensus standards. This 
proposed rulemaking involves technical standards. EPA proposes to use 
Toxicity Characteristic Leaching Procedure (TCLP) for treatment 
standards for associated with hazardous metal constituents in wastes 
proposed for listing in today's proposal. The TCLP is the standard test 
method used to evaluate the toxicity characteristic for the definition 
of hazardous waste (see 40 CFR 261.24) and treatment standards for 
metal constituents under the Land Disposal Restrictions (see 40 CFR 
268.40 and 268.48.). The Agency has used the TCLP in completing its 
treatment standards for the same hazardous metal constituents across a 
range of listed and characteristic hazardous wastes. The performance 
level for leachability is based on the Best Commercially-Available 
Demonstrated Technology (BDAT). The use of the TCLP for the same 
constituents assures uniformity and consistency in the treatment of 
hazardous waste in fulfillment of the Congressional Mandate to minimize 
long-term threats to human health or the environment. 42 U.S.C. 
6924(m). The use of any voluntary consensus standard would be 
impractical with applicable law because it would require a different 
leaching method than is currently used to determine hazardous 
characteristics. The use of different chemical methods to assess 
hazardousness of the waste and compliance with treatment standards 
would create disparate results between hazardous waste identification 
and effective treatment of land disposed hazardous wastes. We have not, 
therefore, used any voluntary consensus standards. EPA welcomes 
comments on this aspect of the proposed rulemaking and, specifically, 
invites the public to identify potentially-applicable voluntary 
consensus standards and to explain why such standards should be used in 
this regulation. EPA has also issued an advanced notice of proposed 
rulemaking for the Land Disposal Restriction program (65 FR 37932, June 
19, 2000) that has included discussion on the effectiveness of 
stabilization on metals in hazardous wastes.

List of Subjects

40 CFR Part 148

    Environmental protection, Administrative practice and procedure, 
Hazardous waste, Reporting and recordkeeping requirements, Water 
supply.

40 CFR Part 261

    Environmental protection, Hazardous materials, Waste treatment and 
disposal, Recycling.

40 CFR Part 268

    Environmental protection, Hazardous materials, Waste management, 
Reporting and recordkeeping requirements, Land Disposal Restrictions, 
Treatment Standards.

40 CFR Part 271

    Environmental protection, Administrative practice and procedure, 
Confidential business information, Hazardous material transportation, 
Hazardous waste, Indians-lands, Intergovernmental relations, Penalties, 
Reporting and recordkeeping requirements, Water pollution control, 
Water supply.

40 CFR Part 302

    Environmental protection, Air pollution control, Chemicals, 
Emergency Planning and Community Right-to-Know Act, Extremely hazardous 
substances, Hazardous chemicals, Hazardous materials, Hazardous 
materials transportation, Hazardous substances, Hazardous wastes, 
Intergovernmental relations, Natural resources, Reporting and 
recordkeeping requirements, Superfund, Waste treatment and disposal, 
Water pollution control, Water supply.

    Dated: August 30, 2000.
Carol M. Browner,
Administrator.
    For the reasons set forth in the preamble, title 40, chapter I of 
the Code of Federal Regulations is proposed to be amended as follows:

PART 148--HAZARDOUS WASTE INJECTION RESTRICTIONS

    1. The authority citation for Part 148 continues to read as 
follows:

    Authority: Secs. 3004, Resource Conservation and Recovery Act, 
42 U.S.C. 6901 et seq.

    2. Section 148.18 is amended by adding paragraphs (l) and (m) to 
read as follows:


Sec. 148.19  Waste-specific prohibitions newly listed and identified 
wastes.

* * * * *
    (l) Effective [date six months after publication of final rule], 
the wastes specified in 40 CFR 261.32 as EPA Hazardous Waste Numbers 
K176, K177, and K178 are prohibited from underground injection.
    (m) The requirements of paragraphs (a) through (l) of this section 
do not apply:
    (1) If the wastes meet or are treated to meet the applicable 
standards specified in subpart D of part 268 of this chapter; or
    (2) If an exemption from a prohibition has been granted in response 
to a petition under subpart C of this part; or
    (3) During the period of extension of the applicable effective 
date, if an extension has been granted under Sec. 148.4.

PART 261--IDENTIFICATION AND LISTING OF HAZARDOUS WASTE

    3. The authority citation for Part 261 continues to read as 
follows:

    Authority: 42 U.S.C. 6905, 6912(a), 6921, 6922, 6924(y), and 
6938.


[[Page 55779]]


    4. Section 261.4 is amended by revising paragraph (b)(15) to read 
as follows:


Sec. 261.4  Exclusions.

* * * * *
    (b) * * *
    (15) Leachate or gas condensate collected from landfills where 
certain solid wastes have been disposed, provided that:
    (i) The solid wastes disposed would meet one or more of the listing 
descriptions for Hazardous Waste Codes K169, K170, K171, K172, K174, 
K175, K176, K177, and K178, if these wastes had been generated after 
the effective date of the listing;
    (ii) The solid wastes described in paragraph (b)(15)(i) of this 
section were disposed prior to the effective date of the listing:
    (iii) The leachate or gas condensate do not exhibit any 
characteristic of hazardous waste nor are derived from any other listed 
hazardous waste;
    (iv) Discharge of the leachate or gas condensate, including 
leachate or gas condensate transferred from the landfill to a POTW by 
truck, rail, or dedicated pipe, is subject to regulation under Sections 
307(b) or 402 of the Clean Water Act.
    (v) After February 13, 2001, leachate or gas condensate derived 
from K169-K172 will no longer be exempt if it is stored or managed in a 
surface impoundment prior to discharge. After [date 24 months after 
publication date of the final rule], leachate or gas condensate derived 
from K176, K177, and K178 will no longer be exempt if it is stored or 
managed in a surface impoundment prior to discharge. There is one 
exception: if the surface impoundment is used to temporarily store 
leachate or gas condensate in response to an emergency situation (e.g., 
shutdown of wastewater treatment system), provided the impoundment has 
a double liner, and provided the leachate or gas condensate is removed 
from the impoundment and continues to be managed in compliance with the 
conditions of paragraph (b)(15)(v) after the emergency ends.
* * * * *
    5. In Sec. 261.32, the table is amended by adding in alphanumeric 
order (by the first column) the following wastestreams to the subgroup 
``Inorganic Chemicals'' to read as follows:


Sec. 261.32  Hazardous waste from specific sources.

* * * * *

----------------------------------------------------------------------------------------------------------------
                                                                                                      Hazardous
    Industry and EPA hazardous waste No.                        Hazardous waste                         code
----------------------------------------------------------------------------------------------------------------
 
*                  *                  *                  *                  *                  *
                                                        *
 Inorganic chemicals:
 
*                  *                  *                  *                  *                  *
                                                        *
K176......................................  Baghouse filters from the production of antimony oxide          (E)
K177......................................  Slag from the production of antimony oxide that is              (T)
                                             disposed of or speculatively accumulated.
 K178.....................................   Nonwastewaters from the production of titanium                 (T)
                                             dioxide by the chloride-ilmenite process. [This
                                             listing does not apply to chloride process waste
                                             solids from titanium tetrachloride production exempt
                                             under section 261.4(b)(7)].
 
 *                  *                  *                  *                  *                  *
                                                         *
----------------------------------------------------------------------------------------------------------------

* * * * *
    6. Appendix VII to Part 261 is amended by adding the following 
wastestreams in alphanumeric order (by the first column) to read as 
follows:

       Appendix VII to Part 261--Basis for Listing Hazardous Waste
------------------------------------------------------------------------
                                            Hazardous constituents for
        EPA hazardous waste No.                   which listed
------------------------------------------------------------------------
 
                  *        *        *        *        *
 K176.................................   Arsenic, lead.
 K177.................................   Antimony.
 K178.................................   Manganese, thallium.
------------------------------------------------------------------------

* * * * *
    7. Appendix VIII to Part 261 is amended by adding in alphabetical 
sequence of common name the following entries:

                                Appendix VIII to Part 261--Hazardous Constituents
----------------------------------------------------------------------------------------------------------------
                                                                                         Chemical
                  Common name                          Chemical abstracts name          abstracts     Hazardous
                                                                                           No.        waste No.
----------------------------------------------------------------------------------------------------------------
 
 *                  *                  *                  *                  *                  *
                                                         *
 Manganese...................................   Same................................    7439-96-5   ............
 
 *                  *                  *                  *                  *                  *
                                                         *
----------------------------------------------------------------------------------------------------------------

PART 268--LAND DISPOSAL RESTRICTIONS

    8. The authority citation for Part 268 continues to read as 
follows:

    Authority: 42 U.S.C. 6905, 6912(a), 6921, and 6924.

Subpart C--Prohibitions on Land Disposal

    9. Section 268.36 is added to read as follows:

[[Page 55780]]

Sec. 268.36  Waste specific prohibitions--inorganic chemical wastes.

    (a) Effective [date six months from date of publication of final 
rule], the wastes specified in 40 CFR Part 261 as EPA Hazardous Wastes 
Numbers K176, K177, and K178, and soil and debris contaminated with 
these wastes, radioactive wastes mixed with these wastes, and soil and 
debris contaminated with radioactive wastes mixed with these wastes are 
prohibited from land disposal.
    (b) The requirements of paragraph (a) of this section do not apply 
if:
    (1) The wastes meet the applicable treatment standards specified in 
Subpart D of this Part;
    (2) Persons have been granted an exemption from a prohibition 
pursuant to a petition under Sec. 268.6, with respect to those wastes 
and units covered by the petition;
    (3) The wastes meet the applicable treatment standards established 
pursuant to a petition granted under Sec. 268.44;
    (4) Hazardous debris has met the treatment standards in Sec. 268.40 
or the alternative treatment standards in Sec. 268.45; or
    (5) Persons have been granted an extension to the effective date of 
a prohibition pursuant to Sec. 268.5, with respect to these wastes 
covered by the extension.
    (c) To determine whether a hazardous waste identified in this 
section exceeds the applicable treatment standards specified in 
Sec. 268.40, the initial generator must test a sample of the waste 
extract or the entire waste, depending on whether the treatment 
standards are expressed as concentrations in the waste extract or the 
waste, or the generator may use knowledge of the waste. If the waste 
contains regulated constituents in excess of the applicable Subpart D 
levels, the waste is prohibited from land disposal, and all 
requirements of Part 268 are applicable, except as otherwise specified.
    10. In Sec. 268.40, the Table is amended by adding in alphanumeric 
order new entries for K176, K177, and K178 to read as follows:


Sec. 268.40  Applicability of treatment standards.

* * * * *

                                                        Treatment Standards for Hazardous Wastes
                                                             [Note: NA means not applicable]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                  Regulated hazardous constituent                Wastewaters                      Nonwastewaters
                       Waste description and -----------------------------------------------------------------------------------------------------------
      Waste code       treatment/regulatory                                                                               Concentration in mg/kg5 unless
                           subcategory 1            Common name         CAS 2 number      Concentration in mg/L3, or       noted as ``mg/L TCLP'', or
                                                                                              technology code 4                  technology code
--------------------------------------------------------------------------------------------------------------------------------------------------------
                   *                  *                  *                  *                  *                  *                  *
 K176...............  Baghouse filters from   Antimony..............       7440-36-0  1.9.............................  1.15 mg/L TCLP
                       the production of      Arsenic...............       7440-38-2  1.4.............................  5.0 mg/L TCLP
                       antimony oxide.
                                              Cadmium...............       7440-43-9  0.69............................  0.11 mg/L TCLP
                                              Lead..................       7439-92-1  0.69............................  0.75 mg/L TCLP
                                              Mercury...............       7439-97-6  0.15............................  0.025 mg/L TCLP
 K177...............  Slag from the           Antimony..............       7440-36-0  1.9.............................  1.15 mg/L TCLP
                       production of          Arsenic...............       7440-38-2  1.4.............................  5.0 mg/L TCLP
                       antimony oxide that    Lead..................       7439-92-1  0.60............................  0.75 mg/L TCLP
                       is disposed of or
                       speculatively
                       accumulated.
 K178...............  Nonwastewaters from     1,2,3,4,6,7,8-              35822-39-4  0.000035 or CMBST11.............  0.0025 or CMBST11
                       the production of       Heptachlorodibenzo-p-      67562-39-4  0.000035 or CMBST11.............  0.0025 or CMBST11
                       titanium dioxide by     dioxin (1,2,3,4,6,7,8-                                                   0.0025 or CMBST11
                       the chloride-ilmenite   HpCDD).
                       process. [This         1,2,3,4,6,7,8-
                       listing does not        Heptachlorodibenzofur
                       apply to chloride       an (1,2,3,4,6,7,8-
                       process waste solids    HpCDF).
                       from titanium
                       tetrachloride
                       production exempt
                       under section
                       261.4(b)(7).].
                                              1,2,3,4,7,8,9-              55673-89-7  0.000035 or CMBST11.............  0.0025 or CMBST11
                                               Heptachlorodibenzofur
                                               an (1,2,3,4,7,8,9-
                                               HpCDF).
                                              HxCDDs (All                 34465-46-8  0.000063 or CMBST11.............  0.001 or CMBST11
                                               Hexachlorodibenzo-p-
                                               dioxins).
                                              HxCDFs (All                 55684-94-1  0.000063 or CMBST11.............  0.001 or CMBST11
                                               Hexachlorodibenzofura
                                               ns).
                                              1,2,3,4,6,7,8,9-             3268-87-9  0.000063 or CMBST11.............  0.005 or CMBST11
                                               Octachlorodibenzo-p-
                                               dioxin (OCDD).
                                              1,2,3,4,6,7,8,9-            39001-02-0  0.000063 or CMBST11.............  0.005 or CMBST11
                                               Octachlorodibenzofura
                                               n (OCDF).
                                              PeCDDs (All                 36088-22-9  0.000063 or CMBST11.............  0.001 or CMBST11
                                               Pentachlorodibenzo-p-
                                               dioxins).
                                              PeCDFs (All                 30402-15-4  0.000035 or CMBST11.............  0.001 or CMBST11
                                               Pentachlorodibenzofur
                                               ans).
                                              TCDDs (All                  41903-57-5  0.000063 or CMBST11.............  0.001 or CMBST11
                                               tetrachlorodibenzo-p-
                                               dioxins).
                                              TCDFs (All                  55722-27-5  0.000063 or CMBST11.............  0.001 or CMBST11
                                               tetrachlorodibenzofur
                                               ans).

[[Page 55781]]

 
                                              Manganese.............       7439-96-5  17.1............................  3.6 mg/L TCLP
                                              Thallium..............       7440-28-0  1.4.............................  0.20 mg/L TCLP
                  *                  *                  *                  *                  *                  *                  *
--------------------------------------------------------------------------------------------------------------------------------------------------------
*  *  *  *  *  *  *
FOOTNOTES TO TREATMENT STANDARD TABLE 268.40
 
 1 The waste descriptions provided in this table do not replace waste descriptions in 40 CFR part 261. Descriptions of Treatment/Regulatory
  Subcategories are provided, as needed, to distinguish between applicability of different standards.
2 CAS means Chemical Abstract Services. When the waste code and/or regulated constituents are described as a combination of a chemical with its salts
  and/or esters, the CAS number is given for the parent compound only.
3 Concentration standards for wastewaters are expressed in mg/L and are based on analysis of composite samples.
4 All treatment standards expressed as a Technology Code or combination of Technology Codes are explained in detail in 40 CFR 268.42 Table 1--Technology
  Codes and Descriptions of Technology-Based Standards.
5 Except for Metals (EP or TCLP) and Cyanides (Total and Amenable) the nonwastewater treatment standards expressed as a concentration were established,
  in part, based upon incineration in units operated in accordance with the technical requirements of 40 CFR part 264, Subpart O or 40 CFR part 265,
  Subpart O, or based upon combustion in fuel substitution units operating in accordance with applicable technical requirements. A facility may comply
  with these treatment standards according to provisions in 40 CFR 268.40(d). All concentration standards for nonwastewaters are based on analysis of
  grab samples.
*  *  *  *  *  *  *
11 For these wastes, the definition of CMBST is limited to: (1) combustion units operating under 40 CFR 266, (2) combustion units permitted under 40 CFR
  part 264, Subpart O, or (3) combustion units operating under 40 CFR 265, Subpart O, which have obtained a determination of equivalent treatment under
  268.42(b).

    11. In Sec. 268.48, the Table is amended by adding in alphabetical 
order under the heading of ``Inorganic Constituents'' a new entry to 
read as follows: (The footnotes are republished without change.)


Sec. 268.48  Universal treatment standards.

* * * * *

                                          Universal Treatment Standards
                                         [Note: NA means not applicable]
----------------------------------------------------------------------------------------------------------------
                                                                               Wastewater       Nonwastewater
                                                                                standard           standard
                                                                           -------------------------------------
            Regulated Constituent common name               CAS \1\ number                   Concentration in mg/
                                                                             Concentration   kg \3\ unless noted
                                                                              in mg/l \2\      as ``mg/l TCLP'
----------------------------------------------------------------------------------------------------------------
*                  *                  *                  *                  *                  *
                                                        *
Inorganic Constituents
*                  *                  *                  *                  *                  *
                                                        *
Manganese                                                       7439-96-5             17.1           3.6 mg/l TCLP
*                  *                  *                  *                  *                  *
                                                        *
----------------------------------------------------------------------------------------------------------------
* * * * * * *
\1\ CAS means Chemical Abstract Services. When the waste code and/or regulated constituents are described as a
  combination of a chemical with its salts and/or esters, the CAS number is given for the parent compound only.
\2\ Concentration standards for wastewaters are expressed in mg/L and are based on analysis of composite
  samples.
\3\ Except for Metals (EP or TCLP) and Cyanides (Total and Amenable) the nonwastewater treatment standards
  expressed as a concentration were established, in part, based upon incineration in units operated in
  accordance with the technical requirements of 40 CFR Part 264, Subpart O, or Part 265, Subpart O, or based
  upon combustion in fuel substitution units operating in accordance with applicable technical requirements. A
  facility may comply with these treatment standards according to provisions in 40 CFR 268.40(d). All
  concentration standards for nonwastewaters are based on analysis of grab samples.

* * * * *

PART 271--REQUIREMENTS FOR AUTHORIZATION OF STATE HAZARDOUS WASTE 
PROGRAMS

    12. The authority citation for Part 271 continues to read as 
follows:

    Authority: 42 U.S.C. 6905, 6912(a), and 6926.

    13. Section 271.1(j) is amended by adding the following entries to 
Table 1 and Table 2 in chronological order by date of publication to 
read as follows.


Sec. 271.1  Purpose and scope.

* * * * *
    (j) * * *

[[Page 55782]]



    TABLE 1.--Regulations Implementing the Hazardous and Solid Waste
                           Amendments of 1984
------------------------------------------------------------------------
                        Title of      Federal Register
Promulgation date      regulation         reference      Effective date
------------------------------------------------------------------------
*                  *                  *                  *
                  *                  *                  *
[insert date of    Listing of         [insert Federal   [insert
 signature of       Hazardous Wastes   Register page     effective date
 final rule]        K176, K177, and    numbers]          of final rule]
                    K178
*                  *                  *                  *
                  *                  *                  *
------------------------------------------------------------------------


 Table 2.--Self-Implementing Provisions of the Solid Waste Amendments of
                                  1984
------------------------------------------------------------------------
                   Self-implementing                    Federal Register
  Effective date       provision        RCRA citation       reference
------------------------------------------------------------------------
*                  *                  *                  *
                  *                  *                  *
[effective date    Prohibition on     3004(g)(4)(C)     [date of
 of final rule].    land disposal of   and 3004(m).      publication of
                    K176, K177, and                      final rule] [FR
                    K178 wastes, and                     page numbers].
                    prohibition on
                    land disposal of
                    radioactive
                    waste mixed with
                    K176, K177, and
                    K178 wastes,
                    including soil
                    and debris.
*                  *                  *                  *
                  *                  *                  *
------------------------------------------------------------------------

PART 302--DESIGNATION, REPORTABLE QUANTITIES, AND NOTIFICATION

    14. The authority citation for Part 302 continues to read as 
follows:

    Authority: 42 U.S.C. 9602, 9603, and 9604; 33 U.S.C. 1321 and 
1361.

    15. In Sec. 302.4, Table 302.4 is amended by adding the following 
new entries in alphanumeric order at the end of the table to read as 
follows:


Sec. 302.4  Designation of hazardous substances

* * * * *

                      Table 302.4.--List of Hazardous Substances and Reportable Quantities
                         [Note: All Comments/Notes Are Located at the End of This Table]
----------------------------------------------------------------------------------------------------------------
                                                                   Statutory                      Final RQ
                                          Regulatory -----------------------------------------------------------
     Hazardous substance         CASRN     synonyms                            RCRA Waste                Pounds
                                                          RQ         Code        Number     Category      (Kg)
--------------------------------------------------------------------------------------------------------
 
        *                  *                   *                  *                  *                  *
                                                         *
K176........................  ..........  ..........         *1            4        K176           X   1 (0.454)
Baghouse filters from the
 production of antimony
 oxide.
K177........................  ..........  ..........         *1            4        K177           X       5,000
                                                                                                         (2,270)
Slag from the production of
 antimony oxide.
K178........................  ..........  ..........         *1            4        K178           X           #
Nonwastewaters from the
 production of titanium
 dioxide by the chloride-
 ilmenite process. [This
 listing does not apply to
 chloride process waste
 solids from titanium
 tetrachloride production
 exempt under section
 261.4(b)(7).] .............
----------------------------------------------------------------------------------------------------------------
 Indicates the statutory source as defined by 1, 2, 3, and 4 below.
*                  *                  *                  *                  *                  *
   *
4-Indicates that the statutory source for designation of this hazardous substance under CERCLA is RCRA Section
  3001.
1* Indicates that the 1-pound RQ is a CERCLA statutory RQ.
# The Agency may adjust the statutory RQ for this hazardous substance in a future rulemaking; until then the
  statutory RQ applies.
 
*                  *                  *                  *                  *                  *
   *

[FR Doc. 00-22810 Filed 9-13-00; 8:45 am]
BILLING CODE 6560-50-U