[Federal Register Volume 76, Number 33 (Thursday, February 17, 2011)]
[Proposed Rules]
[Pages 9410-9447]
[FR Doc No: 2011-2866]

Vol. 76

Thursday,

No. 33

February 17, 2011

Part II

Environmental Protection Agency

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40 CFR Part 63

National Emission Standards for Hazardous Air Pollutants: Primary Lead
Smelting; Proposed Rule

Federal Register / Vol. 76, No. 33 / Thursday, February 17, 2011 /
Proposed Rules

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 63

[EPA-HQ-OAR-2004-0305; FRL-9263-2]
RIN 2060-AQ43

National Emission Standards for Hazardous Air Pollutants: Primary
Lead Smelting

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: EPA is proposing amendments to the national emission standards
for hazardous air pollutants (NESHAP) for Primary Lead Smelting to
address the results of the residual risk and technology reviews
conducted as required under sections 112(d)(6) and (f)(2) of the Clean
Air Act (CAA). These proposed amendments include revisions to the
emission limits for lead, the addition of a lead concentration in air
standard, and the modification and addition of testing and monitoring
and related notification, recordkeeping, and reporting requirements. We
are also proposing to revise provisions addressing periods of startup,
shutdown, and malfunction to ensure that they are consistent with a
recent court decision. Finally, we are proposing revisions to the
rule's applicability provision to make it consistent with the
definition of the source category and proposing other minor technical
changes to the standard. We are also responding to a petition for
rulemaking filed on the standard with regard to lead as a surrogate and
regulation of volatile organic compounds (VOC) and acid gases.

DATES: Comments must be received on or before April 4, 2011. Under the
Paperwork Reduction Act, comments on the information collection
provisions are best assured of having full effect if the Office of
Management and Budget (OMB) receives a copy of your comments on or
before March 21, 2011.
    Public Hearing. If anyone contacts EPA requesting to speak at a
public hearing by February 28, 2011, a public hearing will be held on
March 4, 2011.

ADDRESSES: Submit your comments, identified by Docket ID Number EPA-HQ-
OAR-2004-0305, by one of the following methods:
     http://www.regulations.gov: Follow the on-line
instructions for submitting comments.
     E-mail<EMAIL_ADDRESS>Attention Docket ID Number
EPA-HQ-OAR-2004-0305.
     Fax:<PHONE_NUMBER>, Attention Docket ID Number EPA-HQ-
OAR-2004-0305.
     Mail: U.S. Postal Service, send comments to: EPA Docket
Center, EPA West (Air Docket), Attention Docket ID Number EPA-HQ-OAR-
2004-0305, U.S. Environmental Protection Agency, Mailcode: 2822T, 1200
Pennsylvania Ave., NW., Washington, DC 20460. Please include a total of
two copies. In addition, please mail a copy of your comments on the
information collection provisions to the Office of Information and
Regulatory Affairs, Office of Management and Budget (OMB), Attn: Desk
Officer for EPA, 725 17th Street, NW., Washington, DC 20503.
     Hand Delivery: U.S. Environmental Protection Agency, EPA
West (Air Docket), Room 3334, 1301 Constitution Ave., NW., Washington,
DC 20004, Attention Docket ID Number EPA-HQ-OAR-2004-0305. Such
deliveries are only accepted during the Docket's normal hours of
operation, and special arrangements should be made for deliveries of
boxed information.
    Instructions. Direct your comments to Docket ID Number EPA-HQ-OAR-
2004-0305. EPA's policy is that all comments received will be included
in the public docket without change and may be made available on-line
at http://www.regulations.gov, including any personal information
provided, unless the comment includes information claimed to be
confidential business information (CBI) or other information whose
disclosure is restricted by statute. Do not submit information that you
consider to be CBI or otherwise protected through http://www.regulations.gov or e-mail. The http://www.regulations.gov Web site
is an ``anonymous access'' system, which means EPA will not know your
identity or contact information unless you provide it in the body of
your comment. If you send an e-mail comment directly to EPA without
going through http://www.regulations.gov, your e-mail address will be
automatically captured and included as part of the comment that is
placed in the public docket and made available on the Internet. If you
submit an electronic comment, EPA recommends that you include your name
and other contact information in the body of your comment and with any
disk or CD-ROM you submit. If EPA cannot read your comment due to
technical difficulties and cannot contact you for clarification, EPA
may not be able to consider your comment. Electronic files should avoid
the use of special characters, any form of encryption, and be free of
any defects or viruses. For additional information about EPA's public
docket, visit the EPA Docket Center homepage at http://www.epa.gov/epahome/dockets.htm.
    Docket. The EPA has established a docket for this rulemaking under
Docket ID Number EPA-HQ-OAR-2004-0305. All documents in the docket are
listed in the http://www.regulations.gov index. Although listed in the
index, some information is not publicly available, e.g., CBI or other
information whose disclosure is restricted by statute. Certain other
material, such as copyrighted material, is not placed on the Internet
and will be publicly available only in hard copy. Publicly available
docket materials are available either electronically in http://www.regulations.gov or in hard copy at the EPA Docket Center, EPA West,
Room 3334, 1301 Constitution Ave., NW., Washington, DC. The Public
Reading Room is open from 8:30 a.m. to 4:30 p.m., Monday through
Friday, excluding legal holidays. The telephone number for the Public
Reading Room is<PHONE_NUMBER>, and the telephone number for the EPA
Docket Center is<PHONE_NUMBER>.
    Public Hearing. If a public hearing is held, it will begin at 10
a.m. on March 4, 2011 and will be held at EPA's campus in Research
Triangle Park, North Carolina, or at an alternate facility nearby.
Persons interested in presenting oral testimony or inquiring as to
whether a public hearing is to be held should contact Ms. Virginia
Hunt, Office of Air Quality Planning and Standards, Sector Policies and
Programs Division, Metals and Minerals Group (D243-02), U.S.
Environmental Protection Agency, Research Triangle Park, North Carolina
27711; telephone number:<PHONE_NUMBER>.

FOR FURTHER INFORMATION CONTACT: For questions about this proposed
action, contact Ms. Sharon Nizich, Sector Policies and Programs
Division (D243-02), Office of Air Quality Planning and Standards, U.S.
Environmental Protection Agency, Research Triangle Park, North Carolina
27711, telephone<PHONE_NUMBER>; fax number:<PHONE_NUMBER>; and e-mail
address<EMAIL_ADDRESS>For specific information regarding the
risk modeling methodology, contact Ms. Elaine Manning, Health and
Environmental Impacts Division (C539-02), Office of Air Quality
Planning and Standards, U.S. Environmental Protection Agency, Research
Triangle Park, North Carolina 27711; telephone number:<PHONE_NUMBER>;
fax number:<PHONE_NUMBER>; and e-mail address<EMAIL_ADDRESS>
For information about the applicability of

the NESHAP to a particular entity, contact the appropriate person
listed in Table 1 to this preamble.

SUPPLEMENTARY INFORMATION:

                 Table 1--List of EPA Contacts For the NESHAP Addressed in This Proposed Action
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                NESHAP for:                          OECA contact \1\                   OAQPS contact \2\
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Primary Lead Smelting.....................  Maria Malave,<PHONE_NUMBER>,       Sharon Nizich,<PHONE_NUMBER>,
<EMAIL_ADDRESS><EMAIL_ADDRESS>----------------------------------------------------------------------------------------------------------------
\1\ EPA's Office of Enforcement and Compliance Assurance.
\2\ EPA's Office of Air Quality Planning and Standards.

I. Preamble Acronyms and Abbreviations

    Several acronyms and terms used to describe industrial processes,
data inventories, and risk modeling are included in this preamble.
While this may not be an exhaustive list, to ease the reading of this
preamble and for reference purposes, the following terms and acronyms
are defined here:

ADAF Age-dependent Adjustment Factors
AERMOD Air dispersion model used by the HEM-3 model
AEGL Acute Exposure Guideline Levels
ANPRM Advance Notice of Proposed Rulemaking
BACT Best Available Control Technology
CAA Clean Air Act
CBI Confidential Business Information
CEEL Community Emergency Exposure Levels
CEMS Continuous Emissions Monitoring System
CERMS Continuous Emission Rate Monitoring System
CFR Code of Federal Regulations
EJ Environmental Justice
EPA Environmental Protection Agency
ERPG Emergency Response Planning Guidelines
HAP Hazardous Air Pollutants
HI Hazard Index
HEM-3 Human Exposure Model version 3
HON Hazardous Organic National Emissions Standards for Hazardous Air
Pollutants
HQ Hazard Quotient
IRIS Integrated Risk Information System
Km Kilometer
LAER Lowest Achievable Emission Rate
LOAEL Lowest Observed Adverse Effect Level
MACT Maximum Achievable Control Technology
MACT Code Code within the NEI used to identify processes included in
a source category
MIR Maximum Individual Risk
NAAQS National Ambient Air Quality Standard
NAC/AEGL Committee National Advisory Committee for Acute Exposure
Guideline Levels for Hazardous Substances
NAICS North American Industry Classification System
NAS National Academy of Sciences
NATA National Air Toxics Assessment
NESHAP National Emissions Standards for Hazardous Air Pollutants
NEI National Emissions Inventory
NOAEL No Observed Adverse Effects Level
NRC National Research Council
NTTAA National Technology Transfer and Advancement Act
OAQPS EPA's Office of Air Quality Planning and Standards
OECA EPA's Office of Enforcement and Compliance Assurance
OMB Office of Management and Budget
PB-HAP Hazardous air pollutants known to be persistent and bio-
accumulative in the environment
POM Polycyclic Organic Matter
RACT Reasonably Available Control Technology
RBLC RACT/BACT/LAER Clearinghouse
RFA Regulatory Flexibility Act
RfC Reference Concentration
RfD Reference Dose
RTR Residual Risk and Technology Review
SAB Science Advisory Board
SBA Small Business Administration
SCC Source Classification Codes
SF3 2000 Census of Population and Housing Summary File 3
SIP State Implementation Plan
SOP Standard Operating Procedures
SSM Startup, Shutdown, and Malfunction
TOSHI Target Organ-Specific Hazard Index
TPY Tons Per Year
TRIM Total Risk Integrated Modeling System
TTN Technology Transfer Network
UF Uncertainty Factor
UMRA Unfunded Mandates Reform Act
URE Unit Risk Estimate
VOC Volatile Organic Compounds
VOHAP Volatile Organic Hazardous Air Pollutants
WWW Worldwide Web

    Organization of this Document. The following outline is provided to
aid in the location of information in this preamble.

I. Preamble Acronyms and Abbreviations
II. General Information
    A. Does this action apply to me?
    B. Where can I get a copy of this document and other related
information?
    C. What should I consider as I prepare my comments for EPA?
III. Background
    A. What is the statutory authority for this action?
    B. How did we consider the risk results in making decisions for
this proposal?
    C. What other actions are we addressing in this proposal?
IV. Analyses Performed and Background for the Source Category and
MACT Standard
    A. How did we estimate risks posed by the source category?
    B. How did we perform the technology review?
    C. Overview of the source category and MACT standards
V. Analyses Results and Proposed Decisions
    A. What data were used in our risk analyses?
    B. What are the results of the risk assessments and analyses?
    C. What are our proposed decisions on risk acceptability and
ample margin of safety?
    D. What are the results and proposed decisions from the
technology review?
    E. Variability
    F. What other actions are we proposing?
VI. Proposed Action
    A. What actions are we proposing as a result of the residual
risk reviews?
    B. What actions are we proposing as a result of the technology
reviews?
    C. What other actions are we proposing?
    D. Compliance Dates
VII. Request for Comments
VIII.Submitting Data Corrections
IX. Statutory and Executive Order Reviews
    A. Executive Order 12866: Regulatory Planning and Review
    B. Paperwork Reduction Act
    C. Regulatory Flexibility Act
    D. Unfunded Mandates Reform Act
    E. Executive Order 13132: Federalism
    F. Executive Order 13175: Consultation and Coordination With
Indian Tribal Governments
    G. Executive Order 13045: Protection of Children From
Environmental Health Risks and Safety Risks
    H. Executive Order 13211: Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use
    I. National Technology Transfer and Advancement Act
    J. Executive Order 12898: Federal Actions To Address
Environmental Justice in Minority Populations and Low-Income
Populations

II. General Information

A. Does this action apply to me?

    The regulated industrial source category that is the subject of
this proposal is listed in Table 2 to this preamble. Table 2 is not
intended to be exhaustive, but rather provides a guide for readers
regarding entities likely to be affected by this proposed action for
the source categories listed. This standard, and any changes considered
in this rulemaking, would be directly

applicable to sources as a Federal program. Thus, Federal, State,
local, and tribal government entities are not affected by this proposed
action. As defined in the source category listing report published by
EPA in 1992, the Primary Lead Smelting source category is defined as
any facility engaged in producing lead metal from ore concentrates;
including, but not limited to, the following smelting processes:
sintering, reduction, preliminary treatment, and refining
operations.\1\ As discussed in section III. (C)(3), to be consistent
with the 1992 listing, EPA is proposing to change the applicability of
the Primary Lead Smelting NESHAP to apply to any facility that produces
lead metal from lead ore concentrates. Although the source category
name in the 1992 listing will remain Primary Lead Smelting (as in 1992
listing) we are proposing to change the title of the rule to refer to
Primary Lead Processing. For clarification purposes, all references to
lead emissions in this preamble means ``lead compounds'' (which is a
HAP) and all reference to lead production means elemental lead (which
is not a HAP) as provided under CAA 112(b)(7)).
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    \1\ USEPA. Documentation for Developing the Initial Source
Category List--Final Report, USEPA/OAQPS, EPA-450/3-91-030, July,
1992.

                Table 2--Neshap and Industrial Source Categories Affected by This Proposed Action
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              Source category                               NESHAP                NAICS code \1\   MACT code \2\
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Primary Lead Smelting......................  Primary Lead Processing............          331419            0204
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\1\ North American Industry Classification System.
\2\ Maximum Achievable Control Technology.

B. Where can I get a copy of this document and other related
information?

    In addition to being available in the docket, an electronic copy of
this proposal will also be available on the World Wide Web (WWW)
through the Technology Transfer Network (TTN). Following signature by
the EPA Administrator, a copy of this proposed action will be posted on
the TTN's policy and guidance page for newly proposed or promulgated
rules at the following address: http://www.epa.gov/ttn/atw/rrisk/rtrpg.html. The TTN provides information and technology exchange in
various areas of air pollution control.
    Additional information is available on the residual risk and
technology review (RTR) Web page at http://www.epa.gov/ttn/atw/rrisk/rtrpg.html. This information includes source category descriptions and
detailed emissions and other data that were used as inputs to the risk
assessments.

C. What should I consider as I prepare my comments for EPA?

    Submitting CBI. Do not submit information containing CBI to EPA
through http://www.regulations.gov or e-mail. Clearly mark the part or
all of the information that you claim to be CBI. For CBI information on
a disk or CD ROM that you mail to EPA, mark the outside of the disk or
CD ROM as CBI and then identify electronically within the disk or CD
ROM the specific information that is claimed as CBI. In addition to one
complete version of the comment that includes information claimed as
CBI, a copy of the comment that does not contain the information
claimed as CBI must be submitted for inclusion in the public docket. If
you submit a CD ROM or disk that does not contain CBI, mark the outside
of the disk or CD ROM clearly that it does not contain CBI. Information
not marked as CBI will be included in the public docket and EPA's
electronic public docket without prior notice. Information marked as
CBI will not be disclosed except in accordance with procedures set
forth in 40 CFR part 2. Send or deliver information identified as CBI
only to the following address: Roberto Morales, OAQPS Document Control
Officer (C404-02), Office of Air Quality Planning and Standards, U.S.
Environmental Protection Agency, Research Triangle Park, North Carolina
27711, Attention Docket ID Number EPA-HQ-OAR-2004-0305.

III. Background

A. What is the statutory authority for this action?

    Section 112 of the Clean Air Act (CAA) establishes a two-stage
regulatory process to address emissions of hazardous air pollutants
(HAP) from stationary sources. In the first stage, after EPA has
identified categories of sources emitting one or more of the HAP listed
in section 112(b) of the CAA, section 112(d) of the CAA calls for us to
promulgate NESHAP for those sources. ``Major sources'' are those that
emit or have the potential to emit 10 tons per year (TPY) or more of a
single HAP or 25 TPY or more of any combination of HAP. For major
sources, these technology-based standards must reflect the maximum
degree of emission reductions of HAP achievable (after considering
cost, energy requirements, and non-air quality health and environmental
impacts) and are commonly referred to as maximum achievable control
technology (MACT) standards.
    MACT standards must require the maximum degree of emission
reduction through the application of measures, processes, methods,
systems, or techniques, including, but not limited to, measures which
(A) Reduce the volume of or eliminate pollutants through process
changes, substitution of materials or other modifications; (B) enclose
systems or processes to eliminate emissions; (C) capture or treat
pollutants when released from a process, stack, storage, or fugitive
emissions point; (D) are design, equipment, work practice, or
operational standards (including requirements for operator training or
certification); or (E) are a combination of the above. CAA section
112(d)(2)(A)-(E). The MACT standards may take the form of design,
equipment, work practice, or operational standards where EPA first
determines either that, (A) a pollutant cannot be emitted through a
conveyance designed and constructed to emit or capture the pollutants,
or that any requirement for, or use of, such a conveyance would be
inconsistent with law; or (B) the application of measurement
methodology to a particular class of sources is not practicable due to
technological and economic limitations. CAA sections 112(h)(1)-(2).
    The MACT ``floor'' is the minimum control level allowed for MACT
standards promulgated under CAA section 112(d)(3) and may not be based
on cost considerations. For new sources, the MACT floor cannot be less
stringent than the emission control that is achieved in practice by the
best-

controlled similar source. The MACT floors for existing sources can be
less stringent than floors for new sources, but they cannot be less
stringent than the average emissions limitation achieved by the best-
performing 12 percent of existing sources in the category or
subcategory (or the best-performing 5 sources for categories or
subcategories with fewer than 30 sources). In developing MACT
standards, we must also consider control options that are more
stringent than the floor. We may establish standards more stringent
than the floor based on the consideration of the cost of achieving the
emissions reductions, any non-air quality health and environmental
impacts, and energy requirements.
    The EPA is then required to review these technology-based standards
and to revise them ``as necessary (taking into account developments in
practices, processes, and control technologies)'' no less frequently
than every 8 years, under CAA section 112(d)(6). In conducting this
review, EPA is not obliged to completely recalculate the prior MACT
determination. NRDC v. EPA, 529 F.3d 1077, 1084 (D.C. Cir., 2008).
    The second stage in standard-setting focuses on reducing any
remaining ``residual'' risk according to CAA section 112(f). This
provision requires, first, that EPA prepare a Report to Congress
discussing (among other things) methods of calculating the risks posed
(or potentially posed) by sources after implementation of the MACT
standards, the public health significance of those risks, and the
recommendations regarding legislation of such remaining risk. EPA
prepared and submitted this report (Residual Risk Report to Congress,
EPA-453/R-99-001) in March 1999. Congress did not act in response to
the report, thereby triggering EPA's obligation under CAA section
112(f)(2) to analyze and address residual risk.
    Section 112(f)(2) of the CAA requires us to determine for source
categories subject to certain MACT standards, whether the emissions
standards provide an ample margin of safety to protect public health.
If the MACT standards that apply to a source category emitting a HAP
that is ``classified as a known, probable, or possible human carcinogen
do not reduce lifetime excess cancer risks to the individual most
exposed to emissions from a source in the category or subcategory to
less than one-in-one million,'' EPA must promulgate residual risk
standards for the source category (or subcategory) as necessary to
provide an ample margin of safety to protect public health. CAA section
112(f)(2)(A). In doing so, EPA may adopt standards equal to existing
MACT standards if EPA determines that the existing standards are
sufficiently protective. As stated in NRDC v. EPA, 529 F.3d 1077, 1083
(D.C. Dir. 2008), ``If EPA determines that the existing technology-
based standards provide an `ample margin of safety,' then the Agency is
free to readopt those standards during the residual risk rulemaking.''
Section 112(f)(2) of the Clean Air Act further states that EPA must
also adopt more stringent standards, if necessary, to ``prevent taking
into consideration costs, energy, safety, and other relevant factors,
an adverse environmental effect.'' \2\
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    \2\ ``Adverse environmental effect'' is defined in CAA section
112(a)(7) as any significant and widespread adverse effect, which
may be reasonably anticipated to wildlife, aquatic life, or natural
resources, including adverse impacts on populations of endangered or
threatened species or significant degradation of environmental
qualities over broad areas.
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    When Section 112(f)(2) of the CAA was enacted in 1990, it expressly
preserved our use of the two-step process for developing standards to
address any residual risk and our interpretation of ``ample margin of
safety'' developed in the National Emission Standards for Hazardous Air
Pollutants: Benzene Emissions from Maleic Anhydride Plants,
Ethylbenzene/Styrene Plants, Benzene Storage Vessels, Benzene Equipment
Leaks, and Coke By-Product Recovery Plants (Benzene NESHAP) (54 FR
38044, September 14, 1989). The first step in this process is the
determination of acceptable risk. The second step provides for an ample
margin of safety to protect public health, which is the level at which
the standards are set (unless a more stringent standard is required to
prevent, taking into consideration costs, energy, safety, and other
relevant factors, an adverse environmental effect).
    The terms ``individual most exposed,'' ``acceptable level,'' and
``ample margin of safety'' are not specifically defined in the CAA.
However, CAA section 112(f)(2)(B) preserves the interpretation set out
in the Benzene NESHAP, and the Court in NRDC v. EPA, concluded that
EPA's interpretation of subsection 112(f)(2) is a reasonable one. See
NRDC v. EPA, 529 F.3d at 1083 (D.C. Cir. 2008), which says
``[S]ubsection 112(f)(2)(B) expressly incorporates EPA's interpretation
of the Clean Air Act from the Benzene standard, complete with a
citation to the Federal Register.'' See also, A Legislative History of
the Clean Air Act Amendments of 1990, volume 1, p. 877 (Senate debate
on Conference Report). We notified Congress in the Residual Risk Report
to Congress that we intended to use the Benzene NESHAP approach in
making CAA section 112(f) residual risk determinations (EPA-453/R-99-
001, p. ES-11).
    In the Benzene NESHAP, we stated as an overall objective:

    * * * in protecting public health with an ample margin of
safety, we strive to provide maximum feasible protection against
risks to health from hazardous air pollutants by (1) protecting the
greatest number of persons possible to an individual lifetime risk
level no higher than approximately 1-in-1 million; and (2) limiting
to no higher than approximately 1-in-10 thousand [i.e., 100-in-1
million] the estimated risk that a person living near a facility
would have if he or she were exposed to the maximum pollutant
concentrations for 70 years.

    The Agency also stated that, ``The EPA also considers incidence
(the number of persons estimated to suffer cancer or other serious
health effects as a result of exposure to a pollutant) to be an
important measure of the health risk to the exposed population.
Incidence measures the extent of health risks to the exposed population
as a whole, by providing an estimate of the occurrence of cancer or
other serious health effects in the exposed population.'' The Agency
went on to conclude that ``estimated incidence would be weighed along
with other health risk information in judging acceptability.'' As
explained more fully in our Residual Risk Report to Congress, EPA does
not define ``rigid line[s] of acceptability,'' but considers rather
broad objectives to be weighed with a series of other health measures
and factors (EPA-453/R-99-001, p. ES-11). The determination of what
represents an ``acceptable'' risk is based on a judgment of ``what
risks are acceptable in the world in which we live'' (Residual Risk
Report to Congress, p. 178, quoting the Vinyl Chloride decision at 824
F.2d 1165) recognizing that our world is not risk-free.
    In the Benzene NESHAP, we stated that ``EPA will generally presume
that if the risk to [the maximum exposed] individual is no higher than
approximately 1-in-10 thousand, that risk level is considered
acceptable.'' 54 FR 38045. We discussed the maximum individual lifetime
cancer risk as being ``the estimated risk that a person living near a
plant would have if he or she were exposed to the maximum pollutant
concentrations for 70 years.'' Id. We explained that this measure of
risk ``is an estimate of the upper bound of risk based on conservative
assumptions, such as continuous exposure for 24 hours per day for 70
years.'' Id. We

acknowledge that maximum individual lifetime cancer risk ``does not
necessarily reflect the true risk, but displays a conservative risk
level which is an upper-bound that is unlikely to be exceeded.'' Id.
    Understanding that there are both benefits and limitations to using
maximum individual lifetime cancer risk as a metric for determining
acceptability, we acknowledged in the 1989 Benzene NESHAP that
``consideration of maximum individual risk * * * must take into account
the strengths and weaknesses of this measure of risk.'' Id.
Consequently, the presumptive risk level of 100-in-1 million (1-in-10
thousand) provides a benchmark for judging the acceptability of maximum
individual lifetime cancer risk, but does not constitute a rigid line
for making that determination.
    The Agency also explained in the 1989 Benzene NESHAP the following:
``In establishing a presumption for MIR [maximum individual cancer
risk], rather than a rigid line for acceptability, the Agency intends
to weigh it with a series of other health measures and factors. These
include the overall incidence of cancer or other serious health effects
within the exposed population, the numbers of persons exposed within
each individual lifetime risk range and associated incidence within,
typically, a 50-kilometer (km) exposure radius around facilities, the
science policy assumptions and estimation uncertainties associated with
the risk measures, weight of the scientific evidence for human health
effects, other quantified or unquantified health effects, effects due
to co-location of facilities, and co-emission of pollutants.'' Id.
    In some cases, these health measures and factors taken together may
provide a more realistic description of the magnitude of risk in the
exposed population than that provided by maximum individual lifetime
cancer risk alone. As explained in the Benzene NESHAP, ``[e]ven though
the risks judged ``acceptable'' by EPA in the first step of the Vinyl
Chloride inquiry are already low, the second step of the inquiry,
determining an ``ample margin of safety,'' again includes consideration
of all of the health factors, and whether to reduce the risks even
further.'' In the ample margin of safety decision process, the Agency
again considers all of the health risks and other health information
considered in the first step. Beyond that information, additional
factors relating to the appropriate level of control will also be
considered, including costs and economic impacts of controls,
technological feasibility, uncertainties, and any other relevant
factors. Considering all of these factors, the Agency will establish
the standard at a level that provides an ample margin of safety to
protect the public health, as required by CAA section 112(f). 54 FR
38046.

B. How did we consider the risk results in making decisions for this
proposal?

    As discussed in section III.A of this preamble, we apply a two-step
process for developing standards to address residual risk. In the first
step, EPA determines if risks are acceptable. This determination
``considers all health information, including risk estimation
uncertainty, and includes a presumptive limit on maximum individual
lifetime [cancer] risk (MIR) \3\ of approximately 1-in-10 thousand
[i.e., 100-in-1 million].'' 54 FR 38045. In the second step of the
process, EPA sets the standard at a level that provides an ample margin
of safety ``in consideration of all health information, including the
number of persons at risk levels higher than approximately 1-in-1
million, as well as other relevant factors, including costs and
economic impacts, technological feasibility, and other factors relevant
to each particular decision.'' Id.
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    \3\ Although defined as ``maximum individual risk,'' MIR refers
only to cancer risk. MIR, one metric for assessing cancer risk, is
the estimated risk were an individual exposed to the maximum level
of a pollutant for a lifetime.
---------------------------------------------------------------------------

    In past residual risk actions, EPA has presented and considered a
number of human health risk metrics associated with emissions from the
category under review, including: the MIR; the numbers of persons in
various risk ranges; cancer incidence; the maximum non-cancer hazard
index (HI); and the maximum acute non-cancer hazard (72 FR 25138, May
3, 2007; 71 FR 42724, July 27, 2006). In our most recent proposals (75
FR 65068, October 21, 2010 and 75 FR 80220, December 21, 2010), EPA
also presented and considered additional measures of health
information, including: estimates of ``facility-wide'' risks (risks
from all HAP emissions from the facility at which the source category
is located); \4\ demographic analyses (analyses of the distributions of
HAP-related risks across different social, demographic, and economic
groups living near the facilities); and estimates of the risks
associated with the maximum level of emissions which might be allowed
by the current MACT standards (see, e.g., 75 FR 65068, October 21, 2010
and 75 FR 80220, December 21, 2010). EPA also discussed and considered
risk estimation uncertainties. EPA is providing this same type of
information in support of the proposed actions described in this
Federal Register notice.
---------------------------------------------------------------------------

    \4\ EPA previously provided estimates of total facility risk in
a residual risk proposal for coke oven batteries (69 FR 48338,
August 9, 2004).
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    The Agency is considering all available health information to
inform our determinations of risk acceptability and ample margin of
safety under CAA section 112(f). Specifically, as explained in the
Benzene NESHAP, ``the first step judgment on acceptability cannot be
reduced to any single factor'' and thus ``[t]he Administrator believes
that the acceptability of risk under section 112 is best judged on the
basis of a broad set of health risk measures and information.'' 54 FR
at 38046. Similarly, with regard to making the ample margin of safety
determination, as stated in the Benzene NESHAP ``[I]n the ample margin
decision, the Agency again considers all of the health risk and other
health information considered in the first step. Beyond that
information, additional factors relating to the appropriate level of
control will also be considered, including cost and economic impacts of
controls, technological feasibility, uncertainties, and any other
relevant factors.'' Id.
    The Agency acknowledges that flexibility is provided by the Benzene
NESHAP regarding what factors EPA might consider in making
determinations and how they might be weighed for each source category.
In responding to comment on our policy under the Benzene NESHAP, EPA
explained that: ``The policy chosen by the Administrator permits
consideration of multiple measures of health risk. Not only can the MIR
figure be considered, but also incidence, the presence of non-cancer
health effects, and the uncertainties of the risk estimates. In this
way, the effect on the most exposed individuals can be reviewed as well
as the impact on the general public. These factors can then be weighed
in each individual case. This approach complies with the Vinyl Chloride
mandate that the Administrator ascertain an acceptable level of risk to
the public by employing [her] expertise to assess available data. It
also complies with the Congressional intent behind the CAA, which did
not exclude the use of any particular measure of public health risk
from the EPA's consideration with respect to CAA section 112
regulations, and, thereby, implicitly permits consideration of any and
all measures of health risk which the Administrator, in [her] judgment,
believes are appropriate to determining what will `protect the public
health.' '' 54 FR at 38057.
    For example, the level of the MIR is only one factor to be weighed
in

determining acceptability of risks. It is explained in the Benzene
NESHAP that ``an MIR of approximately 1-in-10 thousand should
ordinarily be the upper end of the range of acceptability. As risks
increase above this benchmark, they become presumptively less
acceptable under CAA section 112, and would be weighed with the other
health risk measures and information in making an overall judgment on
acceptability. Or, the Agency may find, in a particular case, that a
risk that includes MIR less than the presumptively acceptable level is
unacceptable in the light of other health risk factors.'' Id. at 38045.
Similarly, with regard to the ample margin of safety analysis, EPA
stated in the Benzene NESHAP that: ``* * * EPA believes the relative
weight of the many factors that can be considered in selecting an ample
margin of safety can only be determined for each specific source
category. This occurs mainly because technological and economic factors
(along with the health-related factors) vary from source category to
source category.'' Id. at 38061.
    EPA wishes to point out that certain health information has not
been considered to date in making residual risk determinations. In
assessing risks to populations in the vicinity of the facilities in
each category, we present estimates of risk associated with HAP
emissions from the source category alone (source category risk
estimates) and HAP emissions from the entire facility at which the
covered source category is located (facility-wide risk estimates). We
do not attempt to characterize the risks associated with all HAP
emissions impacting the populations living near the sources in these
categories. That is, at this time, we do not attempt to quantify those
HAP risks that may be associated with mobile source emissions, natural
source emissions, persistent environmental pollution, or atmospheric
transformation in the vicinity of the sources in these categories.
    The Agency understands the potential importance of considering an
individual's total exposure to HAP in addition to considering exposure
to HAP emissions from the source category and facility. This is
particularly important when assessing non-cancer risks, where
pollutant-specific exposure levels (e.g., Reference Concentration
(RfC)) are based on the assumption that thresholds exist for adverse
health effects. For example, the Agency recognizes that, although
exposures attributable to emissions from a source category or facility
alone may not indicate the potential for increased risk of adverse non-
cancer health effects in a population, the exposures resulting from
emissions from the facility in combination with emissions from all of
the other sources (e.g., other facilities) to which an individual is
exposed may be sufficient to result in increased risk of adverse non-
cancer health effects. In May 2010, the Science Advisory Board (SAB)
advised us ``* * * that RTR assessments will be most useful to decision
makers and communities if results are presented in the broader context
of aggregate and cumulative risks, including background concentrations
and contributions from other sources in the area.'' \5\
---------------------------------------------------------------------------

    \5\ EPA's responses to this and all other key recommendations of
the SAB's advisory on RTR risk assessment methodologies (which is
available at: http://yosemite.epa.gov/sab/sabproduct.nsf/
4AB3966E263D943A8525771F00668381/$File/EPA-SAB-10-007-unsigned.pdf)
are outlined in a memo to this rulemaking docket from David Guinnup
entitled, EPA's Actions in Response to the Key Recommendations of
the SAB Review of RTR Risk Assessment Methodologies.
---------------------------------------------------------------------------

    While we are interested in placing source category and facility-
wide HAP risks in the context of total HAP risks from all sources
combined in the vicinity of each source, we are concerned about the
uncertainties of doing so. At this point, we believe that such
estimates of total HAP risks will have significantly greater associated
uncertainties than for the source category or facility-wide estimates,
and hence compounding the uncertainty in any such comparison. This is
because we have not conducted a detailed technical review of HAP
emissions data for source categories and facilities that have not
previously undergone an RTR review or are not currently undergoing such
review. We are requesting comment on whether and how best to estimate
and evaluate total HAP exposure in our assessments, and, in particular,
on whether and how it might be appropriate to use information from
EPA's National Air Toxics Assessment (NATA) to support such estimates.
We are also seeking comment on how best to consider various types and
scales of risk estimates when making our acceptability and ample margin
of safety determinations under CAA section 112(f). Additionally, we are
seeking comments and recommendations for any other comparative measures
that may be useful in the assessment of the distribution of HAP risks
across potentially affected demographic groups.

C. What other actions are we addressing in this proposal?

1. Startup, Shutdown and Malfunction
    This proposed action would amend the provisions of the existing
NESHAP that apply to periods of startup, shutdown, and malfunction
(SSM). The proposed revisions of these provisions result from a Court
decision that vacated portions of two provisions in EPA's ``General
Provisions'' regulation under CAA section 112, governing the emissions
of HAP during periods of SSM. The current Primary Lead Smelting MACT
includes references to the vacated provisions in the General Provisions
rule.
    We are proposing to revise the Primary Lead Smelting MACT standard
to require affected sources to comply with the emission limitations at
all times and during periods of SSM. Specifically, we are proposing
several revisions to subpart TTT including revising Table 1 to indicate
that the requirements of the General Provisions pertaining to SSM do
not apply and to revise language in Sec.  63.1547 (g)(1) and (2) to
remove the exemption for bag leak detection alarm time attributable to
SSM from total allowed alarm time. For reasons discussed below, we are
also proposing to promulgate an affirmative defense to civil penalties
for exceedances of emission standards caused by malfunctions, as well
as criteria for establishing the affirmative defense. These changes
would go into effect upon the effective date of promulgation of the
final rule.
    The United States Court of Appeals for the District of Columbia
Circuit vacated portions of two provisions in EPA's CAA Section 112
regulations governing the emissions of HAP during periods of SSM.
Sierra Club v. EPA, 551 F.3d 1019 (D.C. Cir. 2008), cert. denied, 130
S. Ct. 1735 (U.S. 2010). Specifically, the Court vacated the SSM
exemptions contained in 40 CFR 63.6(f)(1) and 40 CFR 63.6(h)(1), that
are part of a regulation commonly known as the ``General Provisions
Rule,'' that EPA had promulgated under section 112 of the CAA. When
incorporated into CAA section 112(d) regulations for specific source
categories, these two provisions exempt sources from the requirement to
comply with the otherwise applicable CAA section 112(d) emission
standard during periods of SSM.
    We are proposing the elimination of the SSM exemption in this rule.
Consistent with Sierra Club v. EPA, EPA is proposing standards in this
rule that apply at all times. We are also proposing several revisions
to Table 1 (the General Provisions Applicability table). For

example, we are proposing to eliminate the incorporation of the General
Provisions' requirement that the source develop an SSM plan. We also
are proposing to eliminate or revise certain recordkeeping and
reporting that relate to the SSM exemption. EPA has attempted to ensure
that we have not included in the proposed regulatory language any
provisions that are inappropriate, unnecessary, or redundant in the
absence of the SSM exemption. We are specifically seeking comment on
whether there are any such provisions that we have inadvertently
incorporated or overlooked.
    In proposing standards in this rule, EPA has taken into account
startup and shutdown periods and, for the reasons explained below, has
not proposed different standards for those periods. Information on
periods of startup and shutdown in the industry indicate that emissions
during these periods do not increase. Furthermore, all processes are
controlled by either control devices or work practices and these
controls would not typically be affected by an SSM event. Also,
compliance with the standard already requires averaging of emissions
over a three month period, which accounts for the variability of
emissions that may result during periods of startup and shutdown.
Therefore, separate standards for periods of startup and shutdown are
not being proposed.
    Periods of startup, normal operations, and shutdown are all
predictable and routine aspects of a source's operations. However, by
contrast, malfunction is defined as a ``sudden, infrequent, and not
reasonably preventable failure of air pollution control and monitoring
equipment, process equipment, or a process to operate in a normal or
useful manner * * *'' (40 CFR 63.2). EPA has determined that
malfunctions should not be viewed as a distinct operating mode and,
therefore, any emissions that occur at such times do not need to be
factored into development of CAA section 112(d) standards, which, once
promulgated, apply at all times. In Mossville Environmental Action Now
v. EPA, 370 F.3d 1232, 1242 (D.C. Cir. 2004), the court upheld as
reasonable standards that had factored in variability of emissions
under all operating conditions. However, nothing in section 112(d) or
in case law requires that EPA anticipate and account for the
innumerable types of potential malfunction events in setting emission
standards. See, Weyerhaeuser v. Costle, 590 F.2d 1011, 1058 (D.C. Cir.
1978)(``In the nature of things, no general limit, individual permit,
or even any upset provision can anticipate all upset situations. After
a certain point, the transgression of regulatory limits caused by
`uncontrollable acts of third parties,' such as strikes, sabotage,
operator intoxication or insanity, and a variety of other
eventualities, must be a matter for the administrative exercise of
case-by-case enforcement discretion, not for specification in advance
by regulation.'').
    Further, it is reasonable to interpret section 112(d) as not
requiring EPA to account for malfunctions in setting emission
standards. For example, we note that CAA section 112 uses the concept
of ``best performing'' sources in defining MACT, the level of
stringency that major source standards must meet. Applying the concept
of ``best performing'' to a source that is malfunctioning presents
significant difficulties. The goal of best performing sources is to
operate in such a way as to avoid malfunctions of their units.
    Moreover, even if malfunctions were considered a distinct operating
mode, we believe it would be impracticable to take malfunctions into
account in setting CAA section 112(d) standards for Primary Lead
Smelting. As noted above, by definition, malfunctions are sudden and
unexpected events and it would be difficult to set a standard that
takes into account the myriad different types of malfunctions that can
occur across all sources in the category. Moreover, malfunctions can
vary in frequency, degree, and duration, further complicating standard
setting.
    In the unlikely event that a source fails to comply with the
applicable CAA section 112(d) standards as a result of a malfunction
event, EPA would determine an appropriate response based on, among
other things, the good faith efforts of the source to minimize
emissions during malfunction periods, including preventative and
corrective actions, as well as root cause analyses to ascertain and
rectify excess emissions. EPA would also consider whether the source's
failure to comply with the CAA section 112(d) standard was, in fact,
``sudden, infrequent, not reasonably preventable'' and was not instead
``caused in part by poor maintenance or careless operation.'' 40 CFR
63.2 (definition of malfunction).
    Finally, EPA recognizes that even equipment that is properly
designed and maintained can sometimes fail and that such failure can
sometimes cause or contribute to an exceedance of the relevant emission
standard. (See, e.g., State Implementation Plans: Policy Regarding
Excessive Emissions During Malfunctions, Startup, and Shutdown (Sept.
20, 1999); Policy on Excess Emissions During Startup, Shutdown,
Maintenance, and Malfunctions (Feb. 15, 1983).) EPA is therefore
proposing to add to the final rule an affirmative defense to civil
penalties for exceedances of emission limits that are caused by
malfunctions. See 40 CFR 63.1542 (defining ``affirmative defense'' to
mean, in the context of an enforcement proceeding, a response or
defense put forward by a defendant, regarding which the defendant has
the burden of proof, and the merits of which are independently and
objectively evaluated in a judicial or administrative proceeding). We
also are proposing other regulatory provisions to specify the elements
that are necessary to establish this affirmative defense; the source
must prove by a preponderance of the evidence that it has met all of
the elements set forth in Sec.  63.1551. (See 40 CFR 22.24.) The
criteria ensure that the affirmative defense is available only where
the event that causes an exceedance of the emission limit meets the
narrow definition of malfunction in 40 CFR 63.2 (sudden, infrequent,
not reasonably preventable and not caused by poor maintenance and/or
careless operation). For example, to successfully assert the
affirmative defense, the source must prove by a preponderance of the
evidence that excess emissions ``[w]ere caused by a sudden, short,
infrequent, and unavoidable failure of air pollution control and
monitoring equipment, process equipment, or a process to operate in a
normal or usual manner * * *'' The criteria also are designed to ensure
that steps are taken to correct the malfunction, to minimize emissions
in accordance with Sec. Sec.  63.1543(i) and 63.1544(e) and to prevent
future malfunctions. For example, the source must prove by a
preponderance of the evidence that ``[r]epairs were made as
expeditiously as possible when the applicable emission limitations were
being exceeded * * *'' and that ``[a]ll possible steps were taken to
minimize the impact of the excess emissions on ambient air quality, the
environment and human health * * *.'' In any judicial or administrative
proceeding, the Administrator may challenge the assertion of the
affirmative defense and, if the respondent has not met its burden of
proving all of the requirements in the affirmative defense, appropriate
penalties may be assessed in accordance with section 113 of the Clean
Air Act (see also 40 CFR part 22.77).
    Specifically, we are proposing the following changes to the rule.
     Added general duty requirements in Sec. Sec.  63.1543 and
63.1544 to replace General Provision requirements that reference
vacated SSM provisions.

     Added replacement language that eliminates the reference
to SSM exemptions applicable to performance tests in Sec.  63.1546.
     Added paragraphs in Sec.  63.1549(e) requiring the
reporting of malfunctions as part of the affirmative defense
provisions.
     Added paragraphs in Sec.  63.1549(b) requiring the keeping
of certain records during malfunctions as part of the affirmative
defense provisions.
     Revised Table 1 to reflect changes in the applicability of
the General Provisions to this subpart resulting from a court vacatur
of certain SSM requirements in the General Provisions.
2. Lead as a Surrogate and Regulation of Volatile Organic Compounds
(VOC) and Acid Gas Emissions
    In a January 14, 2009, petition for rulemaking filed by the Natural
Resources Defense Council and Sierra Club, the petitioners claim that
for the Primary Lead Smelting MACT, EPA relied on lead as a surrogate
for all HAP and they claim that it was inappropriate for EPA to do so
in absence of a showing that lead is an appropriate surrogate for all
other HAP (such as mercury, acid gases, and volatile organic compounds
(VOC)). The petitioners asserted that EPA should set standards for
other HAP absent a showing that lead is an appropriate surrogate for
these HAP. They also assert that EPA's PM standard does not reflect the
emission level achieved by the best performing sources and that EPA
must re-open the rule to set floors for PM in accordance with CAA
section 112(d)(3). A copy of the petition is included in the docket.
    As part of this rulemaking, EPA is responding to the claims made by
the petitioners regarding the Primary Lead Smelting MACT.
    As an initial matter, the petitioners are incorrect in their claim
that EPA considers lead as a surrogate for all HAP. Rather, EPA used
lead as a surrogate only for other metal HAP compounds in establishing
the emissions limit in the current MACT standard for this source
category (63 FR 19206 and 64 FR 30195). EPA determined in the 1999 rule
that lead, a nonvolatile metal HAP, is an appropriate surrogate for
other nonvolatile metal HAP including antimony, arsenic, chromium,
nickel, manganese, and cadmium. In the proposed rule for the Primary
Lead Smelting MACT (63 FR 19206), EPA discussed the use of lead as a
surrogate for metal HAP emissions and explained that strong
correlations exist between emissions of lead and other metal HAP and
that the technologies identified for the control of metal HAP are the
same as those used to control lead emissions. Therefore, EPA expected
that the standards requiring control of lead would achieve similar
control of the other metal HAP emitted from primary lead smelters. No
adverse comments were received regarding EPA's proposed rationale for
relying on lead as a surrogate for other metal HAP emitted by these
sources and EPA adopted that rationale in the final rule promulgating
the Primary Lead Smelting MACT. The petitioners do not have any
substantive basis as to why EPA's rationale is not supported. Nor do
they claim that there is any new information that would support re-
opening this issue. Thus they fail to present a basis for re-opening
this issue.
    The petitioners also insist that EPA should have set standards for
VOC and acid gases that are HAP because lead would not be a surrogate
for these pollutants. EPA noted in the original proposal that due to
small amounts of coke fed to the blast furnace, organic HAP (VOC) was
emitted at a rate so low as to be infeasible to reduce. Again, no
adverse comments were received on EPA's proposed conclusions, which
were adopted in the final rule, and the petitioners do not now provide
substantive support for their claim. Nor do they explain why any such
claim could not have been raised during the initial rulemaking. Thus,
they fail to present a basis for re-opening the rule on this issue.
    Finally, petitioners claim that the ``PM standard does not reflect
the emission level achieved by the best performing sources.'' This
claim is unclear as there is no PM standard in the Primary Lead
Smelting MACT. The monitoring provisions provide that PM should be
measured in relation to a predetermined PM level as one test for
indicating baghouse performance. However, the PM levels are not
enforceable emission limits, but merely an indication that the baghouse
may not be operating properly. Again, these provisions were clearly
explained in the proposed and final Primary Lead Smelting MACT
rulemakings. Any claims concerning the appropriateness of these
monitoring requirements should have been raised during the initial
rulemaking process. Petitioners do not claim any new grounds for
raising this issue now. Thus, the petition fails to provide a basis for
re-opening the MACT.
3. Modification of the Applicability Provision
    EPA is proposing to amend the applicability section to apply to any
facility processing lead ore concentrate to produce lead metal. Under
the current applicability provisions, the affected sources include any
sinter machine, blast furnace, dross furnace, process fugitive source,
and fugitive dust source located at a primary lead smelter and excludes
secondary lead smelters, lead refiners, or lead remelters. Combined
with the current definition for ``primary lead smelter,'' the current
rule effectively only applies to facilities that produce lead metal
from lead sulfide ore concentrates using pyrometallurgical techniques.
While the only processes available for the production of lead from lead
ore concentrate at the time the MACT rule was developed were
pyrometallurgical techniques, that applicability language is narrower
than the primary lead smelting source category description EPA
identified in its source category listing issued pursuant to CAA
section 112(c)(1), Documentation for Developing the Initial Source
Category List (EPA-450/3-91-030, July 1992). In the source category
listing, EPA defined the primary lead smelting source category as
follows: ``The Primary Lead Smelting source category includes any
facility engaged in producing lead metal from ore concentrates. The
category includes, but is not limited to, the following smelting
processes: sintering reduction, preliminary treatment, and refining
operations. The sintering process includes an updraft or downdraft
sintering machine. The reduction process includes the blast furnace,
electric smelting furnace with a converter or reverberatory furnace,
and slag fuming furnace process units. The preliminary treatment
process includes the drossing kettles and dross reverberatory furnace
process units. The refining process includes the refinery process
unit.'' The definition is clear that the primary intent was to cover
sources that produce lead metal from ore concentrates, which would
``include'' the use of a pyrometallurgical process, but would not be
limited to such. As noted previously, at the time we promulgated the
MACT standard, the only method of producing lead metal from ore
concentrates was through use of pyrometallurgical techniques and we
adopted an applicability provision that focused on that process.
    However, information provided by the sole operating primary lead
smelting facility indicates that lead production is likely to continue
at the current Doe Run facility, although using a process other than a
pyrometallurgical technique. The new lead facility would continue to
process lead ore concentrate

in order to produce lead metal. Based on the current applicability
section and definitions, it could be interpreted that the future lead
producing process, using techniques other than pyrometallurgical, would
not be subject to the NESHAP for primary lead smelters. Such a limited
interpretation is not consistent with EPA's intent as evidenced by the
broader definition in the source category list. Therefore, EPA is
proposing to amend the applicability section to specify that the MACT
applies to any lead processing facility that produces lead metal from
lead ore concentrate. Consistent with the proposed revision to the
applicability section, we are proposing to remove the definition of
``primary lead smelter'' and add a definition of ``primary lead
processor'' which means any facility engaged in the production of lead
metal from lead sulfide ore concentrates through the use of
pyrometallurgical or other techniques. In addition, we are proposing to
replace ``primary lead smelter'' with ``primary lead processor''
throughout 40 CFR subpart TTT. (Sec.  63.1541 through Sec.  63.1545,
Sec.  63.1547 through Sec.  63.1549). We are specifically asking for
comment on this proposed change in the definition.
    Because there is only one primary lead processing facility in the
U.S., there will be no impact of this change on the number of existing
facilities covered by the MACT.
    We note, however, that although we are changing the applicability
section to clarify that the MACT applies to all processes for producing
lead metal from ore concentrates, we are not today proposing a specific
MACT standard that would apply to the as-yet undemonstrated
hydrometallurgical process which Doe Run has indicated that it plans to
build at the current Doe Run facility. If and when that process begins
operation, we will consider whether to revise the MACT standard to
specifically address that process or any other new processes. However,
the limits applicable to specific emission sources currently in
operation as specified in the MACT and as revised under CAA sections
112(d)(6) and (f)(2) in this rulemaking would continue to apply to any
emission source at the facility that continues in operation, such as
the refinery. In addition, to the extent that we establish a final air
lead concentration limit as proposed in Sec.  63.1544, those limits
would also continue to apply to the facility. We also are proposing
that the plant-wide emission limit we are proposing today should
continue to apply to any facility that meets the revised applicability
definition, but we are specifically soliciting comment on whether it
should apply.
    We are also taking this opportunity to clarify the reference to
``lead refiners'' in the second sentence of the applicability section,
which provides that the MACT standard does not apply to ``secondary
lead smelters, lead refiners, or lead remelters.'' The intent of this
provision was to make clear that secondary lead smelters would not be
subject to the rule because secondary lead smelters were listed as a
separate source category and addressed in a separate MACT standard.
With regard to lead refiners and lead remelters, the intent was to
provide that these activities, to the extent that they are not located
at facilities that produce lead from lead ore concentrate, would not be
subject to the Primary Lead Smelting MACT. However, it was not the
intention of the rule to exempt kettle refining operations included as
part of a primary lead processing facility. Therefore, EPA is proposing
to add definitions for secondary lead smelters, lead refiners, and lead
remelters in the definitions section of this NESHAP in order to further
clarify the exemption in the applicability provisions with regard to
these types of facilities. As this change only clarifies an existing
provision in the rule, there will be no impact to the number of
facilities covered by the rule.
4. Other Changes
    The following lists additional minor changes we are proposing. This
list includes rule changes that address editorial errors and plain
language revisions.
     As part of EPA's effort to incorporate plain language into
its regulations, replaced the word ``shall'' with ``must.'' (Sec.
63.1543 through Sec.  63.1550)
     Correction to the original rule (``thru'' replaced with
``through'' in the definition of ``tapping location''). (Sec.  63.1542)
     Minor wording change to definition of ``fugitive dust
source'' to clarify meaning. (Sec.  63.1542)

IV. Analyses Performed and Background of the Source Category and MACT
Standard

    As discussed above, in this proposed rule we are proposing action
to address the RTR requirements of CAA sections 112(d)(6) and (f)(2)
for the Primary Lead Smelting MACT standard. In this section, we
describe the analyses performed to support the proposed decisions for
the RTR for this source category and we also include background
information on the source category and the MACT standard.

A. How did we estimate risks posed by the source category?

    The EPA conducted a risk assessment that provided estimates of the
MIR posed by the HAP emissions from the one source in the source
category, the distribution of cancer risks within the exposed
populations, cancer incidence, HI for chronic exposures to HAP with the
potential to cause non-cancer health effects, hazard quotients (HQ) for
acute exposures to HAP with the potential to cause non-cancer health
effects, and an evaluation of the potential for adverse environmental
effects. The risk assessments consisted of seven primary steps, as
discussed below.
    The docket for this rulemaking contains the following document
which provides more information on the risk assessment inputs and
models: Draft Residual Risk Assessment for the Primary Lead Smelting
Source Category.
1. Establishing the Nature and Magnitude of Actual Emissions and
Identifying the Emissions Release Characteristics
    For the Primary Lead Smelting source category, we compiled a
preliminary dataset using readily available information, reviewed the
data, and made changes where necessary. The preliminary dataset was
based on data in the 2002 National Emissions Inventory (NEI) Final
Inventory, Version 1 (made publicly available on February 26, 2006).
The NEI is a database that contains information about sources that emit
criteria air pollutants, their precursors, and HAP. The NEI database
includes estimates of annual air pollutant emissions from point, non-
point, and mobile sources in the 50 States, the District of Columbia,
Puerto Rico, and the Virgin Islands. The EPA collects this information
and releases an updated version of the NEI database every 3 years.
    On December 4, 2009, a CAA Section 114 Information Collection
Request (ICR) was issued requesting information from the one facility
in this source category. An updated dataset was created through
incorporation of changes to the dataset from the ICR data review
process and additional information gathered by EPA. The updated dataset
contains information for the one facility in the source category and
was used to conduct the risk assessment and other analyses that form
the basis for the proposed risk and technology reviews. A copy of the
dataset used and documentation of the risk assessment can be found in
the docket.

2. Establishing the Relationship Between Actual Emissions and MACT-
Allowable Emissions Levels
    The available emissions data in the NEI and from other sources
typically represent the estimates of mass of emissions actually emitted
during the specified annual time period. These ``actual'' emission
levels are often lower than the emission levels that a facility might
be allowed to emit and still comply with the MACT standards. The
emissions level allowed to be emitted by the MACT standards is referred
to as the ``MACT-allowable'' emissions level. This represents the
highest emissions level that could be emitted by the facility without
violating the MACT standards.
    We discussed the use of both MACT-allowable and actual emissions in
the final Coke Oven Batteries residual risk rule (70 FR 19998-19999,
April 15, 2005) and in the proposed and final Hazardous Organic NESHAP
(HON) residual risk rules (71 FR 34428, June 14, 2006, and 71 FR 76609,
December 21, 2006, respectively). In those previous actions, we noted
that assessing the risks at the MACT-allowable level is inherently
reasonable since these risks reflect the maximum level sources could
emit and still comply with national emission standards. But we also
explained that it is reasonable to consider actual emissions, where
such data are available, in both steps of the risk analysis, in
accordance with the Benzene NESHAP. (54 FR 38044, September 14, 1989.)
It is reasonable to consider actual emissions because sources typically
seek to perform better than required by emission standards to provide
an operational cushion to accommodate the variability in manufacturing
processes and control device performance.
    As described above, the actual emissions data were compiled based
on the NEI, information gathered from the facility and State, and
information received in response to the ICR. To estimate emissions at
the MACT-allowable level, we developed a ratio of MACT-allowable to
actual emissions for each source type (i.e., the individual stacks and
the aggregate fugitive emissions) for the one facility in the source
category. This ratio is based on the level of control required by the
MACT standards compared to the level of reported actual emissions and
available information on the level of control achieved by the emissions
controls in use. For example, if there was information to suggest that
an emission point type was being controlled by 98 percent while the
MACT standards required only 92 percent control, we would estimate that
MACT-allowable emissions from that emission point type could be as much
as 4 times higher (8 percent allowable emissions compared with 2
percent actually emitted), and the ratio of MACT-allowable to actual
would be 4:1 for this emission point type. After developing these
ratios for each emission point type at the one facility in this source
category, we next applied these ratios to the maximum chronic risk
estimates from the inhalation risk assessment to obtain maximum risk
estimates based on MACT-allowable emissions. The estimate of MACT-
allowable emissions for the Primary Lead Smelting source category is
described in section V of this preamble.
3. Conducting Dispersion Modeling, Determining Inhalation Exposures,
and Estimating Individual and Population Inhalation Risks
    Both long-term and short-term inhalation exposure concentrations
and health risks from the source category addressed in this proposal
were estimated using the Human Exposure Model (Community and Sector
HEM-3 version 1.1.0). The HEM-3 performs three of the primary risk
assessment activities listed above: (1) Conducting dispersion modeling
to estimate the concentrations of HAP in ambient air, (2) estimating
long-term and short-term inhalation exposures to individuals residing
within 50 km of the modeled sources, and (3) estimating individual and
population-level inhalation risks using the exposure estimates and
quantitative dose-response information.
    The dispersion model used by HEM-3 is AERMOD, which is one of EPA's
preferred models for assessing pollutant concentrations from industrial
facilities.\6\ To perform the dispersion modeling and to develop the
preliminary risk estimates, HEM-3 draws on three data libraries. The
first is a library of meteorological data, which is used for dispersion
calculations. This library includes 1 year of hourly surface and upper
air observations for 130 meteorological stations, selected to provide
coverage of the United States and Puerto Rico. However, in this
instance, site-specific meteorological data for the one facility in
this source category were supplied by the state of Missouri and used
for the modeling. The data provided by the state of Missouri were for
eight quarters (i.e., eight three-month periods) from April 1997
through June 1999. To obtain one year of meteorological data, we used
the middle portion of these data, the year 1998, in our modeling. A
second library of United States Census Bureau census block \7\ internal
point locations and populations provides the basis of human exposure
calculations (Census, 2000). In addition, for each census block, the
census library includes the elevation and controlling hill height,
which are also used in dispersion calculations. A third library of
pollutant unit risk factors and other health benchmarks is used to
estimate health risks. These risk factors and health benchmarks are the
latest values recommended by EPA for HAP and other toxic air
pollutants. These values are available at http://www.epa.gov/ttn/atw/toxsource/summary.html and are discussed in more detail later in this
section.
---------------------------------------------------------------------------

    \6\ U.S. EPA. Revision to the Guideline on Air Quality Models:
Adoption of a Preferred General Purpose (Flat and Complex Terrain)
Dispersion Model and Other Revisions (70 FR 68218, November 9,
2005).
    \7\ A census block is generally the smallest geographic area for
which census statistics are tabulated.
---------------------------------------------------------------------------

    In developing the risk assessment for chronic exposures, we used
the estimated annual average ambient air concentration of each of the
HAP emitted by each source for which we have emissions data in the
source category. The air concentrations at each nearby census block
centroid were used as a surrogate for the chronic inhalation exposure
concentration for all the people who reside in that census block. We
calculated the MIR for the one facility as the cancer risk associated
with a lifetime (70-year period) of exposure to the maximum
concentration at the centroid of an inhabited census block. Individual
cancer risks were calculated by multiplying the estimated lifetime
exposure to the ambient concentration of each of the HAP (in micrograms
per cubic meter) by its Unit Risk Estimate (URE), which is an upper
bound estimate of an individual's probability of contracting cancer
over a lifetime of exposure to a concentration of 1 microgram of the
pollutant per cubic meter of air. In general, for residual risk
assessments, we use URE values from EPA's Integrated Risk Information
System (IRIS). For carcinogenic pollutants without EPA IRIS values, we
look to other reputable sources of cancer dose-response values, often
using California Environmental Protection Agency (CalEPA) URE values,
where available. In cases where new, scientifically credible dose-
response values have been developed in a manner consistent with EPA
guidelines and have undergone a peer review process similar to that
used by

EPA, we may use such dose response values in place of, or in addition
to, other values, if appropriate. In this review, IRIS values were
available for both carcinogenic pollutants (cadmium and arsenic)
emitted by the facility in this source category, and therefore IRIS
values were used in the assessment.
    Incremental individual lifetime cancer risks associated with
emissions from the one source in the source category were estimated as
the sum of the risks for each of the carcinogenic HAP (including those
classified as carcinogenic to humans, likely to be carcinogenic to
humans, and suggestive evidence of carcinogenic potential \8\) emitted
by the modeled source. Cancer incidence and the distribution of
individual cancer risks for the population within 50 km of the source
were also estimated for the source category as part of these
assessments by summing individual risks. A distance of 50 km is
consistent with both the analysis supporting the 1989 Benzene NESHAP
(54 FR 38044) and the limitations of Gaussian dispersion models,
including AERMOD.
---------------------------------------------------------------------------

    \8\ These classifications also coincide with the terms ``known
carcinogen, probable carcinogen, and possible carcinogen,''
respectively, which are the terms advocated in the EPA's previous
Guidelines for Carcinogen Risk Assessment, published in 1986 (51 FR
33992, September 24, 1986). Summing the risks of these individual
compounds to obtain the cumulative cancer risks is an approach that
was recommended by the EPA's SAB in their 2002 peer review of EPA's
NATA entitled, NATA--Evaluating the National-scale Air Toxics
Assessment 1996 Data--an SAB Advisory, available at: http://
yosemite.epa.gov/sab/sabproduct.nsf/
214C6E915BB04E14852570CA007A682C/$File/ecadv02001.pdf.
---------------------------------------------------------------------------

    To assess risk of non-cancer health effects from chronic exposures,
we summed the HQ for each of the HAP that affects a common target organ
system to obtain the HI for that target organ system (or target organ-
specific HI, TOSHI). The HQ is the estimated exposure divided by the
chronic reference value, which is either the EPA RfC, defined as ``an
estimate (with uncertainty spanning perhaps an order of magnitude) of a
continuous inhalation exposure to the human population (including
sensitive subgroups) that is likely to be without an appreciable risk
of deleterious effects during a lifetime,'' or, in cases where an RfC
is not available, the Agency for Toxic Substances and Disease Registry
(ATSDR) chronic Minimal Risk Level (MRL) or the CalEPA Chronic
Reference Exposure Level (REL). The REL is defined as ``the
concentration level at or below which no adverse health effects are
anticipated for a specified exposure duration.''
    Screening estimates of acute exposures and risks were also
evaluated for each of the HAP at the point of highest off-site exposure
for each facility (i.e., not just the census block centroids) assuming
that a person was located at this spot at a time when both the peak
(hourly) emission rate and hourly dispersion conditions occurred. In
general, acute HQ values were calculated using best available, short-
term dose-response value. These acute dose-response values include REL,
Acute Exposure Guideline Levels (AEGL), and Emergency Response Planning
Guidelines (ERPG) for 1-hour exposure durations. Notably, for HAP
emitted from this source category, REL values were the only such dose-
response values available. As discussed below, we used conservative
assumptions for emission rates, meteorology, and exposure location for
our acute analysis.
    As described in the CalEPA's Air Toxics Hot Spots Program Risk
Assessment Guidelines, Part I, The Determination of Acute Reference
Exposure Levels for Airborne Toxicants, an acute REL value (http://www.oehha.ca.gov/air/pdf/acuterel.pdf) is defined as ``the
concentration level at or below which no adverse health effects are
anticipated for a specified exposure duration is termed the REL. REL
values are based on the most sensitive, relevant, adverse health effect
reported in the medical and toxicological literature. REL values are
designed to protect the most sensitive individuals in the population by
the inclusion of margins of safety. Since margins of safety are
incorporated to address data gaps and uncertainties, exceeding the REL
does not automatically indicate an adverse health impact.
    To develop screening estimates of acute exposures, we first
developed estimates of maximum hourly emission rates by multiplying the
average actual annual hourly emission rates by a factor to cover
routinely variable emissions. We chose the factor to use based on
process knowledge and engineering judgment and with awareness of a
Texas study of short-term emissions variability, which showed that most
peak emission events, in a heavily-industrialized 4-county area
(Harris, Galveston, Chambers, and Brazoria Counties, Texas) were less
than twice the annual average hourly emission rate. The highest peak
emission event was 74 times the annual average hourly emission rate,
and the 99th percentile ratio of peak hourly emission rate to the
annual average hourly emission rate was 9.\9\ This analysis is provided
in Appendix 4 of the Draft Residual Risk Assessment for Primary Lead
Smelting which is available in the docket for this action. Considering
this analysis, unless specific process knowledge or data are available
to provide an alternate value, to account for more than 99 percent of
the peak hourly emissions, we apply a conservative screening
multiplication factor of 10 to the average annual hourly emission rate
in these acute exposure screening assessments. For the Primary Lead
Smelting source category, this factor of 10 was applied.
---------------------------------------------------------------------------

    \9\ See http://www.tceq.state.tx.us/compliance/field_ops/eer/index.html or docket to access the source of these data.
---------------------------------------------------------------------------

    In cases where all acute HQ values from the screening step were
less than or equal to 1, acute impacts were deemed negligible and no
further analysis was performed. In the cases where an acute HQ from the
screening step was greater than 1, additional site-specific data were
considered to develop a more refined estimate of the potential for
acute impacts of concern. Ideally, we would prefer to have continuous
measurements over time to see how the emissions vary by each hour over
an entire year. Having a frequency distribution of hourly emission
rates over a year would allow us to perform a probabilistic analysis to
estimate potential threshold exceedances and their frequency of
occurrence. Such an evaluation could include a more complete
statistical treatment of the key parameters and elements adopted in
this screening analysis. However, we recognize that having this level
of data is rare, hence our use of the multiplier (i.e., factor of 10)
approach in our screening analysis.
4. Conducting Multipathway Exposure and Risk Modeling
    The potential for significant human health risks due to exposures
via routes other than inhalation (i.e., multipathway exposures) and the
potential for adverse environmental impacts were evaluated in a three-
step process. In the first step, we determined whether any facilities
emitted any HAP known to be persistent and bio-accumulative in the
environment (PB-HAP). There are 14 PB-HAP compounds or compound classes
identified for this screening in EPA's Air Toxics Risk Assessment
Library (available at http://www.epa.gov/ttn/fera/risk_atra_vol1.html). They are cadmium compounds, chlordane, chlorinated
dibenzodioxins and furans, dichlorodiphenyldichloroethylene,
heptachlor, hexachlorobenzene,

hexachlorocyclohexane, lead compounds, mercury compounds, methoxychlor,
polychlorinated biphenyls, POM, toxaphene, and trifluralin. Emissions
of two PB HAP were identified in the emissions inventory for the
Primary Lead Smelting source category: Lead compounds and cadmium
compounds.
    Cadmium emissions were evaluated for potential non-inhalation risks
and adverse environmental impacts using our recently developed
screening scenario that was developed for use with the TRIM.FaTE model.
This screening scenario uses environmental media outputs from the peer-
reviewed TRIM.FaTE to estimate the maximum potential ingestion risks
for any specified emission scenario by using a generic farming/fishing
exposure scenario that simulates a subsistence environment. The
screening scenario retains many of the ingestion and scenario inputs
developed for EPA's Human Health Risk Assessment Protocols (HHRAP) for
hazardous waste combustion facilities. In the development of the
screening scenario a sensitivity analysis was conducted to ensure that
its key design parameters were established such that environmental
media concentrations were not underestimated, and to also minimize the
occurrence of false positives for human health endpoints. See Appendix
3 of the risk assessment document for a complete discussion of the
development and testing of the screening scenario, as well as for the
values of facility-level de minimis emission rates developed for
screening potentially significant multi-pathway impacts. For the
purpose of developing de minimis emission rates for our cadmium multi-
pathway screening, we derived emission levels for cadmium at which the
maximum human health risk would be 1-in-1 million for lifetime cancer
risk.
    In evaluating the potential air-related multi-pathway risks from
the emissions of lead compounds from the one facility in this source
category, rather than developing a de minimis emission rate, we
compared its maximum modeled 3-month average atmospheric lead
concentration at any off-site location with the current primary
National Ambient Air Quality Standard (NAAQS) for lead (promulgated in
2008), which is set to a level of 0.15 micro-grams per cubic meter
([micro]g/m\3\) based on a rolling 3-month period with a not-to-be-
exceeded form, and which will require attainment by 2016. 73 FR 66964.
Notably, in making these comparisons, we estimated maximum rolling 3-
month ambient lead concentrations taking into account all of the
elements of the NAAQS for lead. That is, our estimated 3-month lead
concentrations are calculated in a manner that is consistent with the
indicator, averaging time, and form of the NAAQS for lead, and those
estimates are compared to the actual level of the lead NAAQS (0.15
[mu]g/m\3\).
    The NAAQS value, a public health policy judgment, incorporated the
Agency's most recent health evaluation of air effects of lead exposure
for the purposes of setting a national standard. In setting this value,
the Administrator promulgated a standard that was requisite to protect
public health with an adequate margin of safety. We consider values
below the level of the primary NAAQS to protect against multi-pathway
risks because, as mentioned above, the primary NAAQS is set as to
protect public health with an adequate margin of safety. However,
ambient air lead concentrations above the NAAQS are considered to pose
the potential for increased risk to public health. We consider this
NAAQS assessment to be a refined analysis given the numerous health
studies, detailed risk and exposure analyses, and level of external
peer and public review that went into the development of the primary
NAAQS for lead, combined with the site-specific dispersion modeling
analysis performed to develop the ambient concentration estimates due
to emissions from the one Primary Lead Processing facility being
addressed in this RTR. It should be noted, however, that this
comparison does not account for possible population exposures to lead
from sources other than the one being modeled; for example, via
consumption of water from untreated local sources or ingestion of
locally grown food. Nevertheless, the Administrator judged that such a
standard, would protect, with an adequate margin of safety, the health
of children and other at-risk populations against an array of adverse
health effects, most notably including neurological effects,
particularly neurobehavioral and neurocognitive effects, in children.
73 FR 67007. The Administrator, in setting the standard, also
recognized that no evidence-or risk based bright line indicated a
single appropriate level. Instead a collection of scientific evidence
and other information was used to select the standard from a range of
reasonable values. 73 FR 67006.
    We further note that comparing ambient lead concentrations to the
NAAQS for lead, considering the level, averaging time, form and
indicator, also informs whether there is the potential for adverse
environmental effects. This is because the secondary lead NAAQS, which
has the same averaging time, form, and level as the primary standard,
was set to protect the public welfare which includes among other things
soils, water, crops, vegetation and wildlife. CAA section 302(h). Thus,
ambient lead concentrations above the NAAQS for lead also indicate the
potential for adverse environmental effects.
    For additional information on the multi-pathway analysis approach,
see the residual risk documentation as referenced in section IV.A of
this preamble. The EPA solicits comment generally on the modeling
approach used herein to assess air-related lead risks, and specifically
on the use of the lead NAAQS in this analytical construct.
5. Assessing Risks Considering Emissions Control Options
    In addition to assessing baseline inhalation risks and screening
for potential multi-pathway risks, we also estimated risks considering
the potential emission reductions that would be achieved by the
particular control options under consideration. The expected emissions
reductions were applied to the specific HAP and emissions points in the
source category dataset to develop corresponding estimates of risk
reductions.
6. Conducting Other Risk-Related Analyses, Including Facility-Wide
Assessments and Demographic Analyses
a. Facility-Wide Risk
    To put the source category risks in context, for our residual risk
review, we also examine the risks from the entire ``facility,'' where
the facility includes all HAP-emitting operations within a contiguous
area and under common control. In other words, we examine the HAP
emissions not only from the source category of interest, but also
emissions of HAP from all other emission sources at the facility. In
this rulemaking, for the sole facility in the Primary Lead Smelting
source category, there are no other significant HAP emission sources
present. With the exception of organic HAP sources determined to
present insignificant risk, all HAP sources have been included in the
risk analysis. Therefore, the facility-wide risks are the same as the
source category risk and no separate facility-wide analysis was
necessary.
b. Demographic Analysis
    To examine the potential for any environmental justice issues that
might be associated with HAP emissions with this source category, we
evaluated the

distributions of HAP-related cancer and non-cancer risks across
different social, demographic, and economic groups within the
populations living near the one facility in this source category. The
development of demographic analyses to inform the consideration of
environmental justice issues in EPA rulemakings is evolving. EPA offers
the demographic analyses in this rulemaking to inform the consideration
of potential environmental justice issues, and invites public comment
on the approaches used and the interpretations made from the results,
with the hope that this will support the refinement and improve the
utility of such analyses for future rulemakings.
    For the demographic analyses, we focus on the populations within 50
km of any facility with emission sources subject to the MACT standard
(identical to the risk assessment). Based on the emissions for the
source category or the facility, we then identified the populations
that are estimated to have exposures to HAP which result in: (1) Cancer
risks of 1-in-1 million or greater, (2) non-cancer HI of 1 or greater,
and/or (3) ambient lead concentrations above the level of the NAAQS for
lead. We compare the percentages of particular demographic groups
within the focused populations to the total percentages of those
demographic groups nationwide. The results, including other risk
metrics, such as average risks for the exposed populations, are
documented in a technical report in the docket for the source category
covered in this proposal.\10\
---------------------------------------------------------------------------

    \10\ Risk and Technology Review--Analysis of Socio-Economic
Factors for Populations Living Near Primary Lead Smelting
Operations.
---------------------------------------------------------------------------

    The basis for the risk values used in the demographic analyses for
the one facility subject to the Primary Lead Smelting MACT was the
modeling results based on actual emissions levels obtained from the
HEM-3 model described above. The risk values for each census block were
linked to a database of information from the 2000 decennial census that
includes data on race and ethnicity, age distributions, poverty status,
household incomes, and education level. The Census Department
Landview[supreg] database was the source of the data on race and
ethnicity, and the data on age distributions, poverty status, household
incomes, and education level were obtained from the 2000 Census of
Population and Housing Summary File 3 (SF3) Long Form. While race and
ethnicity census data are available at the census block level, the age
and income census data are only available at the census block group
level (which includes an average of 26 blocks or an average of 1,350
people). Where census data are available at the block group level but
not the block level, we assumed that all census blocks within the block
group have the same distribution of ages and incomes as the block
group.
    We focused the analysis on those census blocks where source
category risk results show either estimated lifetime inhalation cancer
risks above 1-in-1 million or chronic non-cancer indices above 1. In
addition, in this case we also focused on those census blocks where
estimated ambient lead concentrations were above the level of the lead
NAAQS. For each of these cases, we determined the relative percentage
of different racial and ethnic groups, different age groups, adults
with and without a high school diploma, people living in households
below the national median income, and for people living below the
poverty line within those census blocks. The specific census population
categories included:
     Total population;
     White;
     African American (or Black);
     Native Americans;
     Other races and multiracial;
     Hispanic or Latino;
     People living below the poverty line;
     Children 18 years of age and under;
     Adults 19 to 64 years of age;
     Adults 65 years of age and over;
     Adults without a high school diploma.
    It should be noted that these categories overlap in some instances,
resulting in some populations being counted in more than one category
(e.g., other races and multiracial and Hispanic). In addition, while
not a specific census population category, we also examined risks to
``Minorities,'' a classification which is defined for these purposes as
all race population categories except white.
    The methodology and the results of the demographic analyses for
this source category are included in the technical report available in
the docket for this action. (Risk and Technology Review--Analysis of
Socio-Economic Factors for Populations Living Near Primary Lead
Smelting Operations).
7. Considering Uncertainties in Risk Assessment
    Uncertainty and the potential for bias are inherent in all risk
assessments, including that performed for the source category addressed
in this proposal. Although uncertainty exists, we believe the approach
that we took, which used conservative tools and assumptions, ensures
that our decisions are health-protective. A brief discussion of the
uncertainties in the emissions dataset, dispersion modeling, inhalation
exposure estimates, and dose-response relationships follows below. A
more thorough discussion of these uncertainties is included in the risk
assessment documentation (Draft Residual Risk Assessment for Primary
Lead Smelting) available in the docket for this action.
a. Uncertainties in the Emissions Dataset
    Although the development of the RTR dataset involved quality
assurance/quality control processes, the accuracy of emissions values
will vary depending on the source of the data, the degree to which data
are incomplete or missing, the degree to which assumptions made to
complete the datasets are accurate, whether and to what extent errors
were made in estimating emissions values, and other factors. The
emission estimates considered in this analysis are annual totals
provided by the facility that do not reflect short-term fluctuations
during the course of a year or variations from year to year. In
contrast, the estimates of peak hourly emission rates for the acute
effects screening assessment were based on multiplication factors
applied to the average annual hourly emission rates (the default factor
of 10 was used for Primary Lead Smelting), which is intended to account
for emission fluctuations due to normal facility operations.
b. Uncertainties in Dispersion Modeling
    While the analysis employed EPA's recommended regulatory dispersion
model, AERMOD, we recognize that there is uncertainty in ambient
concentration estimates associated with any model, including AERMOD. In
circumstances where we had to choose between various model options,
where possible, we selected model options (e.g., rural/urban, plume
depletion, chemistry) that provided an overestimate of ambient
concentrations of the HAP rather than an underestimate. However,
because of practicality and data limitation reasons, some factors
(e.g., building downwash) have the potential in some situations to
overestimate or underestimate ambient impacts. Despite these
uncertainties, we believe that at off-site locations and census block
centroids, the approach considered in the dispersion modeling analysis
should generally yield overestimates of ambient HAP concentrations.

c. Uncertainties in Inhalation Exposure
    The effects of human mobility on exposures were not included in the
assessment. Specifically, short-term mobility and long-term mobility
between census blocks in the modeling domain were not considered.\11\
As a result, this simplification will likely bias the assessment toward
overestimating the highest exposures. In addition, the assessment
predicted the chronic exposures at the centroid of each populated
census block as surrogates for the exposure concentrations for all
people living in that block. Using the census block centroid to predict
chronic exposures tends to over-predict exposures for people in the
census block who live farther from the facility, and under-predict
exposures for people in the census block who live closer to the
facility. Thus, using the census block centroid to predict chronic
exposures may lead to a potential understatement or overstatement of
the true maximum impact for any one individual, but is an unbiased
estimate of average risk and incidence.
---------------------------------------------------------------------------

    \11\ Short-term mobility is movement from one microenvironment
to another over the course of hours or days. Long-term mobility is
movement from one residence to another over the course of a
lifetime.
---------------------------------------------------------------------------

    The assessments evaluate the projected cancer inhalation risks
associated with pollutant exposures over a 70-year period, which is the
assumed lifetime of an individual. In reality, both the length of time
that modeled emissions sources at facilities actually operate (i.e.,
more or less than 70 years), and the domestic growth or decline of the
modeled industry (i.e., the increase or decrease in the number or size
of United States facilities), will influence the future risks posed by
a given source or source category. Depending on the characteristics of
the industry, these factors will, in most cases, result in an
overestimate both in individual risk levels and in the total estimated
number of cancer cases. However, in rare cases, where a facility
maintains or increases its emission levels beyond 70 years, residents
live beyond 70 years at the same location, and the residents spend most
of their days at that location, then the risks could potentially be
underestimated. Annual cancer incidence estimates from exposures to
emissions from these sources would not be affected by uncertainty in
the length of time emissions sources operate. For the specific source
in this source category we anticipate significant reduction in
activities and emissions in the relatively near future. If this
happens, chronic risks based on the continuation of current emission
levels will be over estimated.
    The exposure estimates used in these analyses assume chronic
exposures to ambient levels of pollutants. Because most people spend
the majority of their time indoors, actual exposures may not be as
high, depending on the characteristics of the pollutants modeled. For
many of the HAP, indoor levels are roughly equivalent to ambient
levels, but for very reactive pollutants or larger particles, these
levels are typically lower. This factor has the potential to result in
an overstatement of 25 to 30 percent of exposures.\12\
---------------------------------------------------------------------------

    \12\ U.S. EPA. National-Scale Air Toxics Assessment for 1996.
(EPA 453/R-01-003; January 2001; page 85.)
---------------------------------------------------------------------------

    In addition to the uncertainties highlighted above, there are
several factors specific to the acute exposure assessment that should
be highlighted. The accuracy of an acute inhalation exposure assessment
depends on the simultaneous occurrence of independent factors that may
vary greatly, such as hourly emissions rates, meteorology, and human
activity patterns. In this assessment, we assume that individuals
remain for 1 hour at the point of maximum ambient concentration as
determined by the co-occurrence of peak emissions and worst-case
meteorological conditions. These assumptions would tend to overestimate
actual exposures since it is unlikely that a person would be located at
the point of maximum exposure during the time of worst-case impact.
d. Uncertainties in Dose-Response Relationships
    There are uncertainties inherent in the development of the dose-
response values used in our risk assessments for cancer effects from
chronic exposures and non-cancer effects from both chronic and acute
exposures. Some uncertainties may be considered quantitatively, and
others generally are expressed in qualitative terms. We note as a
preface to this discussion a point on dose-response uncertainty that is
brought out in EPA's 2005 Cancer Guidelines; namely, that ``the primary
goal of EPA actions is protection of human health; accordingly, as an
Agency policy, risk assessment procedures, including default options
that are used in the absence of scientific data to the contrary, should
be health protective.'' (EPA 2005 Cancer Guidelines, pages 1-7.) This
is the approach followed here as summarized in the next several
paragraphs. A complete detailed discussion of uncertainties and
variabilities in dose-response relationships is given in the residual
risk documentation which is available in the docket for this action.
    Cancer URE values used in our risk assessments are those that have
been developed to generally provide an upper bound estimate of risk.
That is, they represent a ``plausible upper limit to the true value of
a quantity'' (although this is usually not a true statistical
confidence limit).\13\ In some circumstances, the true risk could be as
low as zero; however, in other circumstances the risk could be
greater.\14\ When developing an upper bound estimate of risk and to
provide risk values that do not underestimate risk, health-protective
default approaches are generally used. To err on the side of ensuring
adequate health-protection, EPA typically uses the upper bound
estimates rather than lower bound or central tendency estimates in our
risk assessments, an approach that may have limitations for other uses
(e.g., priority-setting or expected benefits analysis).
---------------------------------------------------------------------------

    \13\ IRIS glossary (http://www.epa.gov/NCEA/iris/help_gloss.htm).
    \14\ An exception to this is the URE for benzene, which is
considered to cover a range of values, each end of which is
considered to be equally plausible, and which is based on maximum
likelihood estimates.
---------------------------------------------------------------------------

    Chronic non-cancer reference (RfC and RfD) values represent chronic
exposure levels that are intended to be health-protective levels.
Specifically, these values provide an estimate (with uncertainty
spanning perhaps an order of magnitude) of a continuous inhalation
exposure (RfC) or a daily oral exposure (RfD) to the human population
(including sensitive subgroups) that is likely to be without an
appreciable risk of deleterious effects during a lifetime. To derive
values that are intended to be ``without appreciable risk,'' the
methodology relies upon an uncertainty factor (UF) approach (U.S. EPA,
1993, 1994) which includes consideration of both uncertainty and
variability. When there are gaps in the available information, UF are
applied to derive reference values that are intended to protect against
appreciable risk of deleterious effects. The UF are commonly default
values,\15\ e.g., factors

of 10 or 3, used in the absence of compound-specific data; where data
are available, UF may also be developed using compound-specific
information. When data are limited, more assumptions are needed and
more UF are used. Thus, there may be a greater tendency to overestimate
risk in the sense that further study might support development of
reference values that are higher (i.e., less potent) because fewer
default assumptions are needed. However, for some pollutants, it is
possible that risks may be underestimated.
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    \15\ According to the NRC report, Science and Judgment in Risk
Assessment (NRC, 1994) ``[Default] options are generic approaches,
based on general scientific knowledge and policy judgment, that are
applied to various elements of the risk assessment process when the
correct scientific model is unknown or uncertain.'' The 1983 NRC
report, Risk Assessment in the Federal Government: Managing the
Process, defined default option as ``the option chosen on the basis
of risk assessment policy that appears to be the best choice in the
absence of data to the contrary'' (NRC, 1983a, p. 63). Therefore,
default options are not rules that bind the Agency; rather, the
Agency may depart from them in evaluating the risks posed by a
specific substance when it believes this to be appropriate. In
keeping with EPA's goal of protecting public health and the
environment, default assumptions are used to ensure that risk to
chemicals is not underestimated (although defaults are not intended
to overtly overestimate risk). See EPA, 2004, An Examination of EPA
Risk Assessment Principles and Practices, EPA/100/B-04/001 available
at: http://www.epa.gov/osa/pdfs/ratf-final.pdf.
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    While collectively termed ``UF,'' these factors account for a
number of different quantitative considerations when using observed
animal (usually rodent) or human toxicity data in the development of
the RfC. The UF are intended to account for: (1) Variation in
susceptibility among the members of the human population (i.e., inter-
individual variability); (2) uncertainty in extrapolating from
experimental animal data to humans (i.e., interspecies differences);
(3) uncertainty in extrapolating from data obtained in a study with
less-than-lifetime exposure (i.e., extrapolating from sub-chronic to
chronic exposure); (4) uncertainty in extrapolating the observed data
to obtain an estimate of the exposure associated with no adverse
effects; and (5) uncertainty when the database is incomplete or there
are problems with the applicability of available studies. Many of the
UF used to account for variability and uncertainty in the development
of acute reference values are quite similar to those developed for
chronic durations, but they more often use individual UF values that
may be less than 10. UF are applied based on chemical-specific or
health effect-specific information (e.g., simple irritation effects do
not vary appreciably between human individuals, hence a value of 3 is
typically used), or based on the purpose for the reference value (see
the following paragraph). The UF applied in acute reference value
derivation include: (1) Heterogeneity among humans; (2) uncertainty in
extrapolating from animals to humans; (3) uncertainty in lowest
observed adverse effect (exposure) level to no observed adverse effect
(exposure) level adjustments; and (4) uncertainty in accounting for an
incomplete database on toxic effects of potential concern. Additional
adjustments are often applied to account for uncertainty in
extrapolation from observations at one exposure duration (e.g., 4
hours) to derive an acute reference value at another exposure duration
(e.g., 1 hour).
    As further discussed below, there is no RfD or other comparable
chronic health benchmark value for lead compounds. Thus, to address
multipathway human health and environmental risks associated with
emissions of lead from this facility, ambient lead concentrations were
compared to the NAAQS for lead. In developing the NAAQS for lead, EPA
considered human health evidence reporting adverse health effects
associated with lead exposure, as well as an EPA conducted multipathway
risk assessment that applied models to estimate human exposures to air-
related lead and the associated risk (73 FR 66979). EPA also explicitly
considered the uncertainties associated with both the human health
evidence and the exposure and risk analyses when developing the NAAQS
for lead. For example, EPA considered uncertainties in the relationship
between ambient air lead and blood lead levels (73 FR 66974), as well
as uncertainties between blood lead levels and loss of IQ points in
children (73 FR 66981).
    In considering the evidence and risk analyses and their associated
uncertainties, the EPA Administrator noted his view that there is no
evidence- or risk-based bright line that indicates a single appropriate
level. Instead, he noted, there is a collection of scientific evidence
and judgments and other information, including information about the
uncertainties inherent in many relevant factors, which needs to be
considered together in making this public health policy judgment and in
selecting a standard level from a range of reasonable values (73 FR
66998). In so doing, the Administrator decided that, a level for the
primary lead standard of 0.15 [mu]g/m\3\, in combination with the
specified choice of indicator, averaging time, and form, is requisite
to protect public health, including the health of sensitive groups,
with an adequate margin of safety (73 FR 67006). A thorough discussion
of the health evidence, risk and exposure analyses, and their
associated uncertainties can be found in EPA's final rule revising the
lead NAAQS (73 FR 66970-66981, November 12, 2008).
    We also note the uncertainties associated with the health-based
(i.e., primary) NAAQS are likely less than the uncertainties associated
with dose-response values developed for many of the other HAP,
particularly those HAP for which no human health data exist. In 1988,
EPA's IRIS program reviewed the health effects data regarding lead and
its inorganic compounds and determined that it would be inappropriate
to develop an RfD for these compounds, saying, ``A great deal of
information on the health effects of lead has been obtained through
decades of medical observation and scientific research. This
information has been assessed in the development of air and water
quality criteria by the Agency's Office of Health and Environmental
Assessment (OHEA) in support of regulatory decision-making by the
Office of Air Quality Planning and Standards (OAQPS) and by the Office
of Drinking Water (ODW). By comparison to most other environmental
toxicants, the degree of uncertainty about the health effects of lead
is quite low. It appears that some of these effects, particularly
changes in the levels of certain blood enzymes and in aspects of
children's neurobehavioral development, may occur at blood lead levels
so low as to be essentially without a threshold. The Agency's RfD Work
Group discussed inorganic lead (and lead compounds) at two meetings
(07/08/1985 and 07/22/1985) and considered it inappropriate to develop
an RfD for inorganic lead.'' EPA's IRIS assessment for Lead and
compounds (inorganic) (CASRN 7439-92-1), http://www.epa.gov/iris/subst/0277.htm.
    We also note that because of the multi-pathway, multi-media impacts
of lead, the risk assessment supporting the NAAQS considered direct
inhalation exposures and indirect air-related multi-pathway exposures
from industrial sources like primary and secondary lead smelting
operations. It also considered background lead exposures from other
sources (like contaminated drinking water and exposure to lead-based
paints). In revising the NAAQS for lead, we note that the Administrator
placed more weight on the evidence-based framework and less weight on
the results from the risk assessment, although he did find the risk
estimates to be roughly consistent with and generally supportive of the
evidence-based framework applied in the NAAQS determination. 73 FR
67004. Thus, when revising the NAAQS for lead to protect public health
with an adequate margin of safety, EPA considered both

the health evidence and the risk assessment, albeit to different
extents.
    In addition to the uncertainties discussed above with respect to
chronic, cancer, and the lead NAAQS reference values, there are also
uncertainties associated with acute reference values. Not all acute
reference values are developed for the same purpose, and care must be
taken when interpreting the results of an acute assessment of human
health effects relative to the reference value or values being
exceeded. Where relevant to the estimated exposures, the lack of short-
term dose-response values at different levels of severity should be
factored into the risk characterization as potential uncertainties.
    Although every effort is made to identify peer-reviewed reference
values for cancer and non-cancer effects for all pollutants emitted by
the sources included in this assessment, some hazardous air pollutants
continue to have no peer-reviewed reference values for cancer or
chronic non-cancer or acute effects. Since exposures to these
pollutants cannot be included in a quantitative risk estimate, an
understatement of risk for these pollutants at environmental exposure
levels is possible.
    Additionally, chronic reference values for several of the compounds
included in this assessment are currently under EPA IRIS review (e.g.,
cadmium and nickel), and revised assessments may determine that these
pollutants are more or less potent than the current value. We may re-
evaluate residual risks for the final rulemaking if, as a result of
these reviews, a dose-response metric changes enough to indicate that
the risk assessment supporting this notice may significantly understate
human health risk.
e. Uncertainties in the Multipathway and Environmental Effects
Assessment
    We generally assume that when exposure levels are not anticipated
to adversely affect human health, they also are not anticipated to
adversely affect the environment. For each source category, we
generally rely on the site-specific levels of PB-HAP emissions to
determine whether a full assessment of the multi-pathway and
environmental effects is necessary. For PB-HAPS other than lead (i.e.,
cadmium), site-specific PB-HAP emission levels were far below levels
which would trigger a refined assessment of multi-pathway impacts, thus
we are confident that these types of impacts are insignificant for the
one facility in this source category.
f. Uncertainties in the Facility-Wide Risk Assessment
    We did not conduct a separate facility-wide risk assessment for
this proposal because all of the HAP emission sources at the one
facility subject to the MACT are covered by the MACT standard under
review. Thus, the level of the facility-wide HAP emissions is the same
as the level of emissions from the emissions sources subject to the
MACT standard under review.
g. Uncertainties in the Demographic Analysis
    Our analysis of the distribution of risks across various
demographic groups is subject to the typical uncertainties associated
with census data (e.g., errors in filling out and transcribing census
forms), as well as the additional uncertainties associated with the
extrapolation of census-block group data (e.g., income level and
education level) down to the census block level.

B. How did we perform the technology review?

    Our technology review is focused on the identification and
evaluation of developments in practices, processes, and control
technologies. If a review of available information identifies such
developments, then we conduct an analysis of the technical feasibility
of these developments, along with the impacts (costs, emission
reductions, risk reductions, etc.). We then make a decision on whether
it is necessary to amend the regulation to require any identified
developments.
    Based on specific knowledge of the primary lead smelting source
category, we began by identifying known developments in practices,
processes, and control technologies. For the purpose of this exercise,
we considered any of the following to be a ``development'':
     Any add-on control technology or other equipment that was
not identified and considered during MACT development;
     Any improvements in add-on control technology or other
equipment (that was identified and considered during MACT development)
that could result in significant additional emission reduction;
     Any work practice or operational procedure that was not
identified and considered during MACT development; and
     Any process change or pollution prevention alternative
that could be broadly applied that was not identified and considered
during MACT development.
    In addition to looking back at practices, processes, or control
technologies reviewed at the time we developed the MACT standards, we
reviewed a variety of sources of data to aid in our evaluation of
whether there were additional practices, processes, or controls to
consider. One of these sources of data was subsequent air toxics rules.
Since the promulgation of the MACT standard for the primary lead
smelting source category addressed in this proposal, EPA has developed
air toxics regulations for a number of additional source categories. We
reviewed the regulatory requirements and/or technical analyses
associated with these subsequent regulatory actions to identify any
practices, processes, and control technologies considered in these
efforts that could possibly be applied to emission sources in the
primary lead smelting source category.
    We also consulted EPA's RACT/BACT/LAER Clearinghouse (RBLC). The
terms ``RACT,'' ``BACT,'' and ``LAER'' are acronyms for different
program requirements under the CAA provisions addressing the national
ambient air quality standards. Control technologies, classified as RACT
(Reasonably Available Control Technology), BACT (Best Available Control
Technology), or LAER (Lowest Achievable Emission Rate) apply to
stationary sources depending on whether the sources are existing or
new, and on the size, age, and location of the facility. BACT and LAER
(and sometimes RACT) are determined on a case-by-case basis, usually by
state or local permitting agencies. EPA established the RBLC to provide
a central database of air pollution technology information (including
technologies required in source-specific permits) to promote the
sharing of information among permitting agencies and to aid in
identifying future possible control technology options that might apply
broadly to numerous sources within a category or apply only on a
source-by-source basis. The RBLC contains over 5,000 air pollution
control permit determinations that can help identify appropriate
technologies to mitigate many air pollutant emission streams. We
searched this database to determine whether any practices, processes,
or control technologies are included for the types of processes covered
by the primary lead smelting MACT.
    We also requested information from the facility regarding
developments in practices, processes, or control technology. Finally,
we reviewed other information sources, such as state or

local permitting agency databases and industry-supported databases.

C. Overview of the Source Category and MACT Standards

1. Source Category and MACT Standard
    The National Emission Standard for Primary Lead Smelting (or MACT
rule) was promulgated on June 4, 1999 (64 FR 30194) and codified at 40
CFR part 63, subpart TTT. As promulgated in 1999, the MACT standard
applies to affected sources of HAP at primary lead smelters.\16\ The
MACT defines ``Primary lead smelters'' as ``any facility engaged in the
production of lead metal from lead sulfide ore concentrates through the
use of pyrometallurgical techniques.'' 40 CFR 63.1542. The MACT
standard for the Primary Lead Smelting source category does not apply
to secondary lead smelters, lead remelters, or lead refiners (Sec.
63.1541). Today there is one facility (The Doe Run Company in
Herculaneum, Missouri) operating that is subject to the MACT standards
(See Section V.A. below).
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    \16\ As provided above in section III(C)(3), we are proposing to
change the standard to apply to Primary Lead Processors.
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    At the time of promulgation of the Primary Lead Smelting MACT rule,
there were three operating lead smelters. Due to economic pressures
(decreased market demand for lead) and regulatory pressures, two of the
lead smelting facilities subject to the MACT standard have since been
permanently closed, leaving one primary lead smelter currently
operating in the United States. No new primary lead smelters have been
built in the last 20 years, and no new primary lead processing
facilities using pyrometallurgical techniques are anticipated in the
foreseeable future. The one operating lead smelter is not collocated
with other sources of HAP emissions.
    Lead is used to make various construction and consumer products
such as batteries, paint, glass, piping, and filler. Lead sulfide (PbS)
ore concentrates are the main feed material to primary lead smelters.
The primary lead smelting process consists of lead sulfide concentrate
storage and handling, sintering of ore concentrates, sinter crushing
and handling, smelting of sinter to lead metal, drossing (i.e.,
removing the solid oxide deposits), refining and alloying of lead
metal, and smelting of the drosses.
    HAP are emitted from primary lead smelting as process emissions
(stack), process fugitive emissions, and fugitive dust emissions.
Process emissions are associated with the exhaust gases from sinter
machines and blast and dross furnaces. HAP expected in process
emissions are metals (mostly lead compounds, but also some arsenic,
cadmium, and other metals) and also may include small amounts of
organic compounds that result from incomplete combustion of coke, which
is charged along with sinter to the blast furnace. Process fugitive
emissions occur at various points during the smelting process (such as
during charging and tapping of furnaces) and the only HAP emitted are
metal HAP. Fugitive dust emissions result from the entrainment of dust
due to material handling, vehicle traffic, and wind erosion from
storage piles and the only HAP emitted are metal HAP.
    The MACT standard (40 CFR part 63, subpart TTT) applies to process
emissions (stack) from sinter machines, blast furnaces, and dross
furnaces; process fugitive emissions from sinter, blast furnace,
drossing and refining processes, concentrate handling, and locations
around such processes; and fugitive dust emission sources, such as
roadways, storage piles and the plant yard. Process emissions of lead
compounds from sinter machines, blast furnaces, and dross furnaces, and
process fugitive emissions from the blast furnace and dross furnace
charging, blast furnace and dross furnace tapping, and the sinter
machine (charging, discharging, crushing, and sizing) are limited to
500 grams (g) of lead emissions per mega gram (Mg) of lead produced
(500 g/Mg), which is equal to 1.0 pound (lb) of lead emissions per ton
of lead produced (1 lb/ton). 40 CFR 63.1542(a). A plant-wide limit
format was used for MACT because it was consistent with SIPs, the
commingling of exhaust gases from processes to a single stack made it
impossible to set limits for individual sources, it gave the facilities
more flexibility in complying with the standard, and it promoted
pollution prevention by giving each facility the ability to meet the
emission limit through any combination of source reduction and control
technology options. (63 FR 19208).
    In addition to being subject to the plant-wide emission limit of
the standard, process fugitive emissions must be captured by a hood and
ventilated to a baghouse or equivalent control device and the hood
design and ventilation rate must be consistent with American Conference
of Governmental Industrial Hygienists recommended practices. 40 CFR
63.1543(b). In addition, the sinter machine area fugitives must be
enclosed in a building that is ventilated to a baghouse at a rate that
maintains a positive in-draft through any doorway opening. 40 CFR
63.1543(c). The MACT standard also requires the use of bag leak
detection systems for continuous monitoring of baghouses. 40 CFR
63.1547(c)(9). For fugitive dust sources, as defined in 40 CFR 63.1544,
the MACT standard requires that the owner or operator prepare and
operate at all times according to a standard operating procedures (SOP)
manual. The SOP manual must describe in detail the measures used to
control fugitive dust emissions from plant roadways, material storage
and handling areas, sinter machine areas, blast and dross furnace
areas, and refining and casting operations areas. Existing work
practice manual(s) that describe the measures in place to control
fugitive dust sources required as part of a state implementation plan
for lead satisfy this requirement.
2. MACT as it Applies to Doe Run Company Primary Lead Smelter,
Herculaneum, Missouri
    As stated above, the Doe Run Smelter in Herculaneum, Missouri, is
the sole remaining lead processing facility in the United States