[Federal Register: September 9, 2010 (Volume 75, Number 174)]
[Rules and Regulations]
[Page 54969-55066]
[DOCID:fr09se10-14]

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Part II

Environmental Protection Agency

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40 CFR Parts 60 and 63

National Emission Standards for Hazardous Air Pollutants From the
Portland Cement Manufacturing Industry and Standards of Performance for
Portland Cement Plants; Final Rule

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 60 and 63

[EPA-HQ-OAR-2002-0051; EPA-HQ-OAR-2007-0877; FRL-9189-2]
RIN 2060-AO15, 2060-AO42

National Emission Standards for Hazardous Air Pollutants From the
Portland Cement Manufacturing Industry and Standards of Performance for
Portland Cement Plants

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: EPA is finalizing amendments to the National Emission
Standards for Hazardous Air Pollutants (NESHAP) from the Portland
Cement Manufacturing Industry and to the New Source Performance
Standards (NSPS) for Portland Cement Plants.
    The final amendments to the NESHAP add or revise, as applicable,
emission limits for mercury, total hydrocarbons (THC), and particulate
matter (PM) from new and existing kilns located at major and area
sources, and for hydrochloric acid (HCl) from new and existing kilns
located at major sources. The standards for new kilns apply to
facilities that commence construction, modification, or reconstruction
after May 6, 2009.
    The final amendments to the NSPS add or revise, as applicable,
emission limits for PM, opacity, nitrogen oxides (NOX), and
sulfur dioxide (SO2) for facilities that commence
construction, modification, or reconstruction after June 16, 2008. The
final rule also includes additional testing and monitoring requirements
for affected sources.

DATES: These final rules are effective on November 8, 2010. The
incorporation by reference of certain publications listed in this rule
is approved by the Director of the Federal Register on November 8,
2010.

ADDRESSES: EPA has established two separate dockets for these actions:
Docket ID No. EPA-HQ-OAR-2007-0877 for the amendments to the NSPS and
Docket ID No. EPA-HQ-OAR-2002-0051 for the amendments to the NESHAP.
All documents in the two dockets are listed in the http://
www.regulations.gov index. Certain other material, such as copyrighted
material, 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,
Standards of Performance for Portland Cement Plants Docket, 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 Docket
Center is<PHONE_NUMBER>.

FOR FURTHER INFORMATION CONTACT: Mr. Keith Barnett; Office of Air
Quality Planning and Standards; Sector Policies and Programs Division,
Metals and Minerals Group (D243-02); Environmental Protection Agency;
Research Triangle Park, NC 27711; telephone number:<PHONE_NUMBER>; fax
number:<PHONE_NUMBER>; e-mail address<EMAIL_ADDRESS>
SUPPLEMENTARY INFORMATION: The supplementary information presented in
this preamble is organized as follows:

I. General Information
    A. Does this action apply to me?
    B. Where can I get a copy of this document?
    C. Judicial Review
II. Background Information on the NESHAP, 40 CFR Part 63, Subpart
LLL
    A. What is the statutory basis for the NESHAP in 40 CFR part 63,
subpart LLL?
    B. Summary of the National Lime Association v. EPA Litigation
    C. EPA's Response to the Remand
    D. Reconsideration of EPA Final Action in Response to the Remand
III. Background Information From the NSPS 40 CFR Part 60, Subpart F
IV. Summary of EPA's Final Action on Amendments
    A. What are EPA's final actions on 40 CFR part 63, subpart LLL?
    B. What are EPA's final actions on 40 CFR part 60, subpart F?
    C. What is EPA's sector-based approach?
V. Responses to Major Comments
    A. What are the significant comments and responses on 40 CFR
part 63, subpart LLL?
    B. What are the significant comments and responses on 40 CFR
part 60, subpart F?
VI. Summary of Cost, Environmental, Energy, and Economic Impacts of
the Final Amendments to Subpart LLL and Subpart F
VII. 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 Advancement Act
    J. Executive Order 12898: Federal Actions To Address
Environmental Justice in Minority Populations and Low-Income
Populations
    K. Congressional Review Act

I. General Information

A. Does this action apply to me?

    Categories and entities potentially regulated by this final rule
include:

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                                           NAICS
                Category                  code \1\                 Examples of regulated entities
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Industry...............................     327310  Portland cement manufacturing plants.
Federal government.....................  .........  Not affected.
State/local/Tribal government..........  .........  Portland cement manufacturing plants.
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\1\ North American Industry Classification System.

    This table is not intended to be exhaustive, but rather provides a
guide for readers regarding entities likely to be regulated by this
action. To determine whether your facility will be regulated by this
action, you should examine the applicability criteria in 40 CFR 60.60
(subpart F) or in 40 CFR 63.1340 (subpart LLL). If you have any
questions regarding the applicability of this final action to a
particular entity, contact the person listed in the preceding FOR
FURTHER INFORMATION CONTACT section.

B. Where can I get a copy of this document?

    In addition to being available in the docket, an electronic copy of
this final action is available on the Worldwide Web (WWW) through the
Technology Transfer Network (TTN). Following

signature, a copy of this final action will be posted on the TTN's
policy and guidance page for newly proposed or promulgated rules at
http://www.epa.gov/ttn/oarpg. The TTN provides information and
technology exchange in various areas of air pollution control.

C. Judicial Review

    Under section 307(b)(1) of the Clean Air Act (CAA), judicial review
of these final rules are available only by filing a petition for review
in the United States Court of Appeals for the District of Columbia
Circuit by November 8, 2010. Under section 307(b)(2) of the CAA, the
requirements established by these final rules may not be challenged
separately in any civil or criminal proceedings brought by EPA to
enforce these requirements.
    Section 307(d)(7)(B) of the CAA further provides that ``[o]nly an
objection to a rule or procedure which was raised with reasonable
specificity during the period for public comment (including any public
hearing) may be raised during judicial review.'' This section also
provides a mechanism for EPA to convene a proceeding for
reconsideration, ``[i]f the person raising an objection can demonstrate
to EPA that it was impracticable to raise such objection within [the
period for public comment] or if the grounds for such objection arose
after the period for public comment (but within the time specified for
judicial review) and if such objection is of central relevance to the
outcome of the rule.'' Any person seeking to make such a demonstration
to us should submit a Petition for Reconsideration to the Office of the
Administrator, U.S. EPA, Room 3000, Ariel Rios Building, 1200
Pennsylvania Ave., NW., Washington, DC 20460, with a copy to both the
person(s) listed in the preceding FOR FURTHER INFORMATION CONTACT
section, and the Associate General Counsel for the Air and Radiation
Law Office, Office of General Counsel (Mail Code 2344A), U.S. EPA, 1200
Pennsylvania Ave., NW., Washington, DC 20460.

II. Background Information on the NESHAP, 40 CFR Part 63, Subpart LLL

A. What is the statutory basis for the NESHAP in 40 CFR part 63,
subpart LLL?

    Section 112 of the CAA establishes a regulatory process to address
emissions of hazardous air pollutants (HAP) from stationary sources.
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) requires us
to promulgate NESHAP for those sources. For ``major sources'' 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 a combination of HAP, these technology-
based standards must reflect the maximum 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.
    The statute specifies certain minimum stringency requirements for
MACT standards, which are referred to as ``floor'' requirements. See
CAA section 112(d)(3). Specifically, 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 standards for
existing sources can be less stringent than standards for new sources,
but they cannot be less stringent than the average emission limitation
achieved by the best-performing 12 percent of existing sources (for
which the Administrator has emissions information) in the category or
subcategory (or the best-performing five sources for categories or
subcategories with fewer than 30 sources).
    In developing MACT, 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. CAA section 112(d)(2).
    Section 112(k)(3)(B) of the CAA requires EPA to identify at least
30 HAP that pose the greatest potential health threat in urban areas,
and section 112(c)(3) requires EPA to regulate, under section 112(d)
standards, the area source \1\ categories that represent 90 percent of
the emissions of the 30 ``listed'' HAP (``urban HAP''). We implemented
these listing requirements through the Integrated Urban Air Toxics
Strategy (64 FR 38715, July 19, 1999).\2\
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    \1\ An area source is a stationary source of HAP emissions that
is not a major source. A major source is a stationary source that
emits or has the potential to emit 10 tpy or more of any HAP or 25
tpy or more of any combination of HAP.
    \2\ Since its publication in the Integrated Urban Air Toxics
Strategy in 1999, EPA has amended the area source category list
several times.
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    The Portland cement manufacturing source category was listed for
regulation under this 1999 Urban Strategy based on emissions of
arsenic, cadmium, beryllium, lead, and polychlorinated biphenyls (PCB).
The final NESHAP for the Portland Cement Manufacturing Industry (64 FR
31898, June 14, 1999) included emission limits based on performance of
MACT for the control of THC emissions from area sources. This 1999 rule
fulfills the requirement to regulate area source cement kiln emissions
of PCB (for which THC is a surrogate). However, EPA did not include
requirements for the control of the non-volatile metal HAP (arsenic,
cadmium, beryllium, and lead) from area sources in the 1999 rule or in
the 2006 amendments. To fulfill our requirements under CAA section
112(c)(3) and 112(k), EPA is thus setting emissions standards for these
metal HAP from Portland cement manufacturing facilities that are area
sources (using PM as a surrogate). In this final rule EPA is
promulgating PM standards for area sources based on performance of
MACT, PM being a surrogate for these (and other non-volatile) HAP
metals.
    Section 112(c)(6) requires that EPA list categories and
subcategories of sources assuring that sources accounting for not less
than 90 percent of the aggregate emissions of each of seven specified
HAP are subject to standards under section 112(d)(2) or (d)(4). The
seven HAP are as follows: Alkylated lead compounds; polycyclic organic
matter; hexachlorobenzene; mercury; polychlorinated byphenyls; 2,3,7,8-
tetrachlorodibenzofurans; and 2,3,7,8-tetrachloroidibenzo-p-dioxin.
Standards established under CAA section 112(d)(2) must reflect the
performance of MACT. ``Portland cement manufacturing: Non-hazardous
waste kilns'' is listed as a source category pursuant to CAA section
112(c)(6) due to emissions of polycyclic organic matter (POM), mercury,
and dioxin/furans. Consistent with the requirements of CAA section
112(c)(6), we set MACT standards for these pollutants. 63 FR 17838,
17848, April 10, 1998; see also 63 FR at 14193 (March 24, 1998) (area
source cement kilns' emissions of mercury, dibenzo-p-dioxins and
dibenzo-p-furans, POM, and PCB are subject to MACT).
    Section 129(a)(1)(A) of the CAA requires EPA to establish specific
performance standards, including emission limitations, for ``solid
waste incineration units'' generally, and, in particular, for ``solid
waste incineration units combusting commercial or industrial waste''
(CAA section 129(a)(1)(D)).\3\
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    \3\ CAA section 129 refers to the Solid Waste Disposal Act
(SWDA). However, this Act, as amended is commonly referred to as
RCRA.

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    Section 129 of the CAA defines ``solid waste incineration unit'' as
``a distinct operating unit of any facility which combusts any solid
waste material from commercial or industrial establishments or the
general public.'' CAA Section 129(g)(1). CAA Section 129 also provides
that ``solid waste'' shall have the meaning established by EPA pursuant
to its authority under the Resource Conservation and Recovery Act
(RCRA). Section 129(g)(6).
    In Natural Resources Defense Council v. EPA, 489 F. 3d 1250, 1257-
61 (DC Cir. 2007), the Court vacated the Commercial and Industrial
Solid Waste Incineration Units (CISWI) Definitions Rule, 70 FR 55568
(Sept. 22, 2005), which EPA issued pursuant to CAA section
129(a)(1)(D).
    In response to the Court's remand and vacatur of the CISWI
Definitions rule, EPA initiated a rulemaking to identify which
secondary materials are non-hazardous ``solid waste'' for purposes of
subtitle D (non-hazardous waste) of the RCRA when burned in a
combustion unit. See 75 FR 31844 (June 4, 2010). Any final definition
adopted in that rulemaking, in turn, will determine the applicability
of CAA section 129(a) (i.e., any combustion unit that burns any non-
hazardous secondary material that is considered to be a solid waste
would be subject to CAA section 129 requirements).
    There is presently no Federal regulatory interpretation of ``solid
waste'' for EPA to apply under Subtitle D of RCRA for purposes of CAA
section 112 and 129. EPA is not prejudging, and cannot prejudge the
outcome of the recently proposed non-hazardous solid waste rulemaking.
EPA therefore cannot reliably determine at this time if the non-
hazardous secondary materials combusted by cement kilns are to be
classified as solid wastes. Accordingly, EPA is basing all
determinations as to source classification on the emissions information
now available, as required by CAA section 112(d)(3), and will
necessarily continue to do so until the solid waste definition
discussed above is promulgated. The current data base classifies all
Portland cement kilns as CAA section 112 sources (i.e., subject to
regulation under CAA section 112).
    We proposed amendments to the Portland Cement Manufacturing NESHAP
on May 6, 2009. See 74 FR 21136. We received a total of 3,229 comments
from the Portland cement industry, environmental groups, State
environmental agencies and others during the comment period. This final
rule reflects our consideration of all the comments we received.
Detailed responses to the comments not included in this preamble are
contained in the Summary of Public Comments and Responses document,
which is included in the docket for this rulemaking.

B. Summary of the National Lime Association v. EPA Litigation

    On June 14, 1999 (64 FR 31898), EPA issued the NESHAP for the
Portland Cement Manufacturing Industry (40 CFR part 63, subpart
LLL).\4\ The 1999 final rule established emission limitations for PM as
a surrogate for non-volatile HAP metals (major sources only), dioxins/
furans, and for greenfield \5\ new sources total THC as a surrogate for
organic HAP. These standards were intended to be based on the
performance of MACT pursuant to CAA sections 112(d)(2) and (3). We did
not establish limits for THC for existing sources and non-greenfield
new sources, nor for HCl or mercury for new or existing sources. We
reasoned that emissions of these constituents were a function of raw
material concentrations and so were essentially uncontrolled, the
result being that there was no level of performance on which a floor
could be based. EPA further found that beyond the floor standards for
these HAP were not warranted.
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    \4\ Cement kilns which burn hazardous waste are a separate
source category, since their emissions of many HAP differ from
Portland cement kilns' as a result of the hazardous waste inputs.
Rules for hazardous waste-burning cement kilns are found at subpart
EEE of part 63.
    \5\ For purposes of the 1999 rule a new greenfield kiln is a
kiln constructed after March 24, 1998, at a site where there are no
existing kilns.
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    Ruling on petitions for review of various environmental groups, the
DC Circuit held that EPA had erred in failing to establish CAA section
112(d) standards for mercury, THC (except for greenfield new sources)
and HCl. The court held that ``[n]othing in the statute even suggests
that EPA may set emission levels only for those * * * HAPs controlled
with technology.'' National Lime Ass'n v. EPA, 233 F. 3d 625, 633 (DC
Cir. 2000). The court also stated that EPA is obligated to consider
other pollution-reducing measures such as process changes and material
substitution. Id. at 634 (``the absence of technology-based pollution
control devices for HCl, mercury, and total hydrocarbons did not excuse
EPA from setting emission standards for those pollutants''). Later
cases go on to hold that EPA must account for levels of HAP in raw
materials and other inputs in establishing MACT floors, and further
hold that sources with low HAP emission levels due to low levels of HAP
in their raw materials can be considered best performers for purposes
of establishing MACT floors. See, e.g., Cement Kiln Recycling Coalition
v. EPA, 255 F. 2d 855, 865-66 (DC Cir. 2001); Sierra Club v. EPA
(``Brick MACT''), 479 F. 3d 875, 882-83 (DC Cir. 2007).\6\
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    \6\ In the remainder of the opinion, the Court in National Lime
Ass'n upheld EPA's standards for PM and dioxin (on grounds that
petitioner had not properly raised arguments in its opening brief),
upheld EPA's use of PM as a surrogate for HAP metals, and remanded
for further explanation EPA's choice of an analytic method for HCl.
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C. EPA's Response to the Remand

    In response to the National Lime Ass'n mandate, on December 2,
2005, we proposed standards for mercury, THC, and HCl. (More
information on the regulatory and litigation history may be found at 70
FR 72332, December 2, 2005.) We received over 1,700 comments on the
proposed amendments. Most of these comments addressed the lack of a
mercury emission limitation in the proposed amendments. On December 20,
2006 (71 FR 76518), EPA published final amendments to the NESHAP. The
2006 amendments contained a new source standard for mercury emissions
from cement kilns and kilns/in-line raw mills of 41 micrograms per dry
standard cubic meter, or alternatively the application of a limestone
wet scrubber with a liquid-to-gas ratio of 30 gallons per 1,000 actual
cubic feet per minute of exhaust gas. The final rule also adopted a
standard for new and existing sources banning the use of utility boiler
fly ash in cement kilns where the fly ash mercury content has been
increased through the use of activated carbon or any other sorbent
unless the cement kiln seeking to use the fly ash can demonstrate that
the use of fly ash will not result in an increase in mercury emissions
over its baseline mercury emissions (i.e., emissions not using the
mercury-laden fly ash). EPA also issued a THC standard for new cement
kilns (except for greenfield cement kilns that commenced construction
on or before December 2, 2005) of 20 parts per million (corrected to 7
percent oxygen) or 98 percent reduction in THC emissions from
uncontrolled levels. EPA did not set a standard for HCl, determining
that HCl was a pollutant for which a threshold had been established,
and that no cement kiln, even under conservative operating conditions
and exposure assumptions, would emit HCl at levels that would exceed
that threshold level, allowing for an ample margin of safety. EPA
pointed to CAA section 112(d)(4) authority as its rationale for not
establishing HCl emissions limits.

D. Reconsideration of EPA Final Action in Response to the Remand

    At the same time we issued the final amendments, EPA on its own
initiative made a determination to reconsider the new source standard
for mercury, the existing and new source standard banning cement kiln
use of certain mercury-containing fly ash, and the new source standard
for THC (71 FR 76553, December 20, 2006). EPA granted reconsideration
of the new source mercury standard both due to substantive issues
relating to the performance of wet scrubbers and because information
about their performance in the industry had not been available for
public comment at the time of proposal; that information is now
available in the docket. We also committed to undertake a test program
for mercury emissions from cement kilns equipped with wet scrubbers
that would enable us to resolve these issues. We further explained that
we were granting reconsideration of the work practice requirement
banning the use of certain mercury-containing fly ash in cement kilns
to allow further opportunity for comment on both the standard and the
underlying rationale and because we did not feel we had the level of
analysis we would like to have to support a beyond-the-floor
determination. We granted reconsideration of the new source standard
for THC because the information on which the standard was based arose
after the period for public comment. We requested comment on the actual
standard, whether the standard is appropriate for reconstructed new
sources (if any should occur) and the information on which the standard
is based. We specifically solicited data on THC emission levels from
preheater/precalciner cement kilns. We stated that we would evaluate
all data and comments received, and determine whether in light of those
data and comments it was appropriate to amend the promulgated
standards.
    EPA received comments on the notice of reconsideration from two
cement companies, three energy companies, three industry associations,
a technical consultant, one State, one environmental group, one ash
management company, one fuels company, and one private citizen. As part
of these comments, one industry trade association submitted a petition
to withdraw the new source MACT standards for mercury and THC and one
environmental group submitted a petition for reconsideration of the
2006 final action. A summary of these comments is available in the
docket for this rulemaking.\7\
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    \7\ Summary of Comments on December 20, 2006 Final Rule and
Notice of Reconsideration. April 15, 2009.
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    In addition to the reconsideration discussed above, EPA received a
petition from Sierra Club requesting reconsideration of the existing
source standards for THC, mercury, and HCl, and judicial petitions for
review challenging the final amendments. EPA granted the
reconsideration petition. The judicial petitions have been combined and
are being held in abeyance pending the results of the reconsideration.
    In March 2007 the DC Circuit Court issued an opinion (Sierra Club
v. EPA, 479 F.3d 875 (DC Cir. 2007) (Brick MACT)) vacating and
remanding CAA section 112(d) MACT standards for the Brick and
Structural Clay Ceramics source categories. Some key holdings in that
case were:
     Floors for existing sources must reflect the average
emission limitation achieved by the best performing 12 percent of
existing sources, not levels EPA considers to be achievable by all
sources (479 F. 3d at 880-81);
     EPA cannot set floors of ``no control.'' The Court
reiterated its prior holdings, including National Lime Ass'n,
confirming that EPA must set floor standards for all HAP emitted by the
major source, including those HAP that are not controlled by at-the-
stack control devices (479 F. 3d at 883); and
     EPA cannot ignore non-technology factors that reduce HAP
emissions, including when determining which sources are best performers
for purposes of ascertaining the MACT floor. Specifically, the Court
held that ``EPA's decision to base floors exclusively on technology
even though non-technology factors affect emissions violates the Act.''
(479 F. 3d at 883).
    Based on the statute, as interpreted in the Brick MACT decision, we
believe a source's performance resulting from the presence or absence
of HAP in raw materials must be accounted for in establishing floors;
i.e., a low emitter due to low HAP proprietary raw materials can still
be a best performer. In addition, the fact that a specific level of
performance is not being intentionally achieved by the source is not a
legal basis for excluding the source's performance from consideration.
Sierra Club v. EPA, 479 F.3d at 631-34; National Lime Ass'n, 233 F. 3d
at 640.
    The Brick MACT decision also reiterated that EPA may account for
variability in setting floors. However, the Court found that EPA erred
in assessing variability because it relied on data from the worst
performers to estimate best performers' variability, and held that
``EPA may not use emission levels of the worst performers to estimate
variability of the best performers without a demonstrated relationship
between the two.'' 479 F. 3d at 882.
    After considering the implications of this decision, EPA granted
the petition for reconsideration of all the existing source standards
in the 2006 rulemaking.
    A second Court opinion of relevance to the Portland cement NESHAP
amended here is Sierra Club v. EPA, 551 F. 3d 1019 (DC Cir. 2008). In
that case, the court vacated the regulations contained in the General
Provisions which exempt major sources from CAA section 112(d) standards
during periods of startup, shutdown and malfunction (SSM). The
regulations (in 40 CFR 63.6(f)(1) and 63.6(h)(1)) provided that sources
need not comply with the relevant CAA section 112(d) standard during
SSM events and instead must ``minimize emissions * * * to the greatest
extent which is consistent with safety and good air pollution control
practices.'' The current Portland Cement NESHAP references the now-
vacated rules in the General Provisions. As a result of the court's
decision, we are removing the references to the vacated provisions and
addressing SSM in this rulemaking. Discussion of this issue may be
found in Section IV.A.

III. Background Information on the NSPS 40 CFR Part 60, Subpart F

    NSPS implement CAA section 111(b) and are issued for categories of
sources which cause, or contribute significantly to, air pollution
which may reasonably be anticipated to endanger public health or
welfare. The primary purpose of the NSPS is to attain and maintain
ambient air quality by ensuring that the best demonstrated emission
control technologies are installed as the industrial infrastructure is
modernized. Since 1970, the NSPS have been successful in achieving
long-term emissions reductions in numerous industries by assuring cost-
effective controls are installed on new, reconstructed, or modified
sources.
    Section 111 of the CAA requires that NSPS reflect the application
of the best system of emission reductions which, taking into
consideration the cost of achieving such emission reductions, any non-
air quality health and environmental impact and energy requirements,
the Administrator determines has been adequately

demonstrated. This level of control is commonly referred to as best
demonstrated technology (BDT). EPA promulgated Standards of Performance
for Portland Cement Plants (40 CFR, part 61 subpart F) in 1971 ((36 FR
24876, December 23, 1971).
    Section 111(b)(1)(B) of the CAA requires EPA to periodically review
and revise the standards of performance, as necessary, to reflect
improvements in methods for reducing emissions. We have conducted three
reviews of the standards (39 FR 20793, June 14, 1974; 39 FR 39874,
November 12, 1974; and 53 FR 50354, December 14, 1988).
    We proposed the current review of the Portland Cement Plant NSPS on
June 16, 2008. We received a total of 46 comments from the Portland
cement industry, environmental groups, State environmental agencies and
others during the comment period. This final rule reflects our
consideration of all the comments we received. Detailed responses to
the comments not included in this preamble are contained in the Summary
of Public Comments and Responses document which is included in the
docket for this rulemaking.

IV. Summary of EPA's Final Action on the Amendments

    In this section we discuss the final amendments to 40 CFR part 63
subpart LLL and part 60 subpart F, the changes since proposal, and the
rationale for the changes. Responses to specific comments may be found
in the response to comment section of this document or in the response
to comment documents contained in the dockets for this rulemaking.
    As a preliminary matter, EPA notes that certain portions of the
existing rules are not being amended substantively but are being
reprinted, sometimes with editorial changes, in today's regulatory
text. As explained at proposal, EPA did so either for readers'
convenience or to make certain non-substantive ``plain English''
changes to rule text. 74 FR at 21140. The final rule text makes these
same non-substantive changes (which did not occasion public comment),
and reprints certain existing provisions. Provisions from the existing
rules which do not change substantively include the PM emission limits
for kilns currently subject to the NSPS, the opacity limits for raw
materials dryers, raw mills, and finish mills, and the limits for
dioxin furan (D/F) for cement kilns. We reorganized the testing and
monitoring requirements of both rules to make them more consistent, and
modified the rule language to better conform with the June 1, 1998,
Executive Memorandum on Plain Language in Government Writing.

A. What are EPA's final actions on 40 CFR part 63, subpart LLL?

1. What are the final actions on emission limits under 40 CFR part 63,
subpart LLL?
    In this action, we are amending the emission limits for mercury,
THC, and PM from new and existing kilns located at a major or area
source, and for HCl from new and existing kilns located at major
sources. We identify these standards below for the emission sources in
a typical Portland cement production process. We have applied the
limits for existing and new sources in this final rule for mercury and
THC to area sources consistent with CAA section 112(c)(6). As noted
above, mercury is one of the pollutants specifically singled out by
Congress in CAA section 112(c)(6), and THC is a surrogate for POM and
PCB, which are also section 112(c)(6) HAP. See 63 FR 14193, March 24,
1998 (determination to control all THC emissions from the source
category under MACT standards). Finally, Portland cement kilns are a
listed area source category for urban HAP metals pursuant to CAA
section 112(c)(3), and control of these metal HAP emissions (via the
standard for the PM non-mercury HAP metal surrogate) is required to
ensure that area sources representing 90 percent of the area source
emissions of urban metal HAP are subject to CAA section 112 control, as
required by CAA section 112(c)(3). The PM standards for area sources
reflect MACT, as explained below.
a. Changes to Overall Floor Setting Procedure
    The MACT floor limits for each of the HAP and HAP surrogates
(mercury, THC, HCl, and PM) are calculated based on the performance of
the lowest emitting (considered best performing in this rulemaking)
sources in each of the MACT floor pools for each HAP or HAP surrogate.
We ranked all of the sources for which we had data based on their
emissions and identified the lowest emitting 12 percent of the sources
for which we had data, which ranged from two kilns for THC to 11 kilns
for mercury for existing sources. For new source MACT, the floor was
based on the best controlled source.
    In assessing sources' performance, EPA may consider variability
both in identifying which performers are ``best'' and in assessing
their level of performance. Brick MACT, 479 F. 3d at 881-82; see also
Mossville Envt'l Action Now v. EPA, 370 F.3d 1232, 1241-42 (DC Cir
2004) (EPA must exercise its judgment, based on an evaluation of the
relevant factors and available data, to determine the level of
emissions control that has been achieved by the best performing sources
considering these sources' variability).
    Variability in cement kilns' performance has a number of causes.
For many of the pollutants, notably mercury and THC, most kilns do not
have add-on control devices. The main source of variability for these
pollutants consequently is the differing mercury and organic
concentrations in the raw materials and fuels which are fed to the
kiln. For particulate matter, which is well-controlled by baghouses,
the variability is chiefly due to variations in performance of the
control device for which both run-to-run and test-to-test variability
must be accounted.\8\
---------------------------------------------------------------------------

    \8\ Run-to-run variability is essentially within-test
variability, and encompasses variability in individual runs
comprising the compliance test, and includes uncertainties in
correlation of monitoring parameters and emissions, and imprecision
of stack test methods and laboratory analysis. 72 FR at 54877 (Sept.
27, 2007). Test-to-test variability results from variability in
pollution device control efficiencies over time (depending on many
factors, including for fabric filters the point in the maintenance
cycle in which a fabric filter is tested). Test-to-test variability
can be termed long-term variability. 72 FR at 54878.
---------------------------------------------------------------------------

    In determining the MACT floor limits, we first determine the floor,
which, as explained above, for existing sources is the level achieved
in practice by the average of the top 12 percent of existing sources,
or the level achieved in practice by the best controlled similar source
for new sources. In this rule, EPA is using lowest emissions as the
measure of best performance.
    We then assess variability of the best performers by using a
statistical formula designed to estimate a MACT floor level that is
equivalent to the average of the best performing sources based on
future compliance tests (or calculated inputs in the case of mercury).
Specifically, the MACT floor limit is an upper prediction limit (UPL)
calculated with the Student's t-test using the TINV function in
Microsoft Excel[reg]. The Student's t-test has also been
used in other EPA rulemakings (e.g., NSPS for Hospital/Medical/
Infectious Waste Incinerators, NESHAP for Industrial, Commercial, and
Institutional Boilers and Process Heaters) in accounting for
variability. A prediction interval for a future observation is an
interval that will, with a specified degree of confidence, contain the
next (or some other pre-specified) randomly selected observation from a
population. In other words, the prediction interval estimates what the
upper bound of future values will be, based upon present or past
background samples taken. The UPL

consequently represents the value which we can expect the mean of
future observations (3-run average for HCl, 30-day average for mercury,
PM, HCl (sources not having wet scrubbers or otherwise electing CEM-
based compliance), and THC) to fall below within a specified level of
confidence, based upon the results of an independent sample from the
same population. In other words, if we were to randomly select a future
test condition from any of these sources (i.e., average of 3 runs or
30-day average) we can be 99 percent confident that the reported level
will fall at or below the UPL value. Use of the UPL is appropriate in
this rulemaking because it sets a limit any single or future source can
meet based on the performance of members of the MACT pool.
    This formula uses a pooled variance (in the s \2\ term) that
encompasses all the data-point to data-point variability of the best
performing sources comprising the MACT floor pool for each HAP. Where
variability was calculated using the UPL statistical approach (i.e.,
for the Hg, HCl, and PM standards), we used the average (or sample
mean) and sample standard deviation, which are two statistical measures
calculated from the data distributions for mercury, HCl, and PM. The
average is a central value of a data set, and the standard deviation is
the common measure of the dispersion of the data set around the
average. We describe in detail in the preamble sections on mercury, HCl
and PM and in the memorandum ``Development of the MACT Floors for the
Final NESHAP for Portland Cement'', August 6, 2010'' how these averages
were developed. We note here that the methodology accounts for both
short-term and long-term variability and encompasses run-to-run and
test-to-test variability. The formula also applies differently
depending on how the underlying data set is distributed. To this end,
EPA carefully evaluated the data sets for each HAP to ascertain whether
the data were normally distributed, or distributed in some other manner
(i.e., log normally). After applying standard and rigorous statistical
tests (involving the degree of ``skewness'' of the data), we determined
that the distributions for mercury and particulate matter were
approximately a normal distribution, which in turn determined the final
form of the UPL equation. See Floor Calculations for Final Portland
Cement NESHAP, August 6, 2010; see also 75 FR at 32019-20.
    EPA was able to reasonably calculate variability for the THC and
HCl standards without needing to use predictive statistics.
Specifically, the data set for THC contains a sufficient number of
observations to estimate the variability without the need of any type
of statistical intervals (no UPL needed to be calculated). For HCl,
although EPA applied the UPL formula in developing the HCl standard,
the key issue for the HCl data set is the HCl analytic method's
detection limit, which ultimately dictated the level of the standard.
    At proposal we adopted a form of the UPL equation that has been
used in a previous rulemaking. 69 FR 21233 April 20, 2004. Commenters
stated correctly that there was an error in the equation used at
proposal. As a result of these comments, EPA corrected the formula in
the final rule. The UPL used in the final rule is calculated by:
[GRAPHIC] [TIFF OMITTED] TR09SE10.000

Where:

x = the mean of the sample data set
n = the number of test runs
m = the number of test runs in the compliance average
s\2\ = observed variance
t = student t distribution statistic

This calculation was performed using the following Excel functions:

Normal distribution: 99 percent UPL = AVERAGE(Test Runs in Top
12percent) + [STDEV(Test Runs in Top 12percent) x TINV(2 x probability,
n-1 degrees of freedom)*SQRT((1/n)+(1/m))], for a one-tailed t-value,
probability of 0.01, and sample size of n

This is the same UPL equation that EPA used in more recent rulemakings.
See 75 FR 32020 (June 4, 2010) and 75 FR 31905 (June 4, 2010). The
value of ``m'' denotes the number of future observations, and it is
used to calculate an estimate of the variance of the average of m-
future observations. For example, if 30-day averages are used to
determine compliance (m=30), the amount of variability in the 30-day
average is much lower than the variability of the daily measurements in
the data base, which results in a lower UPL for the 30-day average.
    As an illustration of the effects that correcting the UPL had on
the emission limits, we calculated the UPLs for mercury and PM using
the proposal version of the UPL formula, and the version used in this
final rule. The results of these calculations are presented in Table 1.
Both calculated limits are about 20 percent lower when the corrected
UPL formula is used.

    Table 1--Comparison Emission Limits Calculated Using Proposal UPL
        Formula Versus Corrected UPL Formula for Existing Sources
------------------------------------------------------------------------
                                       Proposal            Proposal
                                   (uncorrected UPL     (corrected UPL
                                       formula)            formula)
------------------------------------------------------------------------
Mercury, (lb/MM tons feed) [lb/          29.6 [48.8]         22.5 [37.1]
 MM tons clinker]...............
PM (lb/ton clinker).............                0.05                0.04
------------------------------------------------------------------------

b. Ramifications of EPA Statistical Approach
    A number of commenters maintained that this final rule raises the
(perceived) quandry voiced by Judge Williams in his concurring opinion
in Brick MACT where an achieved level of performance for purposes of
CAA section 112(d)(3) results in a standard which is unachievable under
CAA section 112(d)(2) because it is too costly or not cost-effective.
Brick MACT, 479 F. 3d at 884-85. EPA is of course mindful of the
repeated admonitions (with accompanying vacaturs and remands) from the
DC Circuit that MACT floors must reflect achieved performance, that HAP
content of process inputs (raw materials and fuels) must be accounted
for in ascertaining sources' performance, and that costs cannot be
considered by EPA in ascertaining the level of the MACT floor. See,
e.g., Brick MACT, 479 F. 3d at 880-81, 882-83; NRDC v. EPA, 489 F. 3d
1364, 1376 (DC Cir. 2007) (``Plywood MACT''); see also Cement Kiln
Recycling Coalition v. EPA, 255 F. 3d 855, 861-62 (DC Cir. 2001)
(``achievability'' requirement of CAA section 112(d)(2) cannot override
the requirement that floors be calculated on the basis of what best
performers actually achieved). EPA is also mindful of the need to
account for sources' variability (both due to control device

performance and variability in inputs) in assessing sources'
performance when developing technology-based standards. See, e.g.,
Mossville Environmental Action Now v. EPA, 370 F. 3d 1232, 1242 (DC
Cir. 2004); National Lime I, 627 F. 2d 416,433-34(DC Cir. 1980). EPA
has carefully developed data for each standard, assessing both
technological controls and HAP inputs in doing so. For mercury, EPA
used the pooled variance from all of the best performing kilns in the
MACT floor pool in order to fully assess these kilns' intra-quarry and
other variable mercury levels. EPA also used pooled variance to assess
the variability of HCl and PM emissions for the MACT floor pool kilns.
See 70 FR at 59438 (Oct. 12, 2005) (explaining when use of such pooled
variances can be reasonable). EPA has also adopted 30-day averaging
periods for all of the standards, further allowing short term
fluctuations to be averaged out over the 30-day period.
    The result are floors which reasonably estimate the performance
over time of the best performing sources, as do the standards based on
those floors. It is true that many sources will need to install
controls to meet these standards, and that these controls have
significant costs (although EPA estimates that the rule's costs are
substantially outweighed by its benefits). See Section VI below. This
is part of the expected MACT process where, by definition, the averaged
performance of the very best performers sets the minimum level of the
standard. The Agency believes that it has followed the statute and
applicable case law in developing its floor methodology.
    Industry commenters nonetheless maintained that EPA had not
properly accounted for variability of the best performing sources
because not even these sources can meet the standards which are
predicated on their own performance without adding controls. This
contention lacks a basis in the record. For mercury, all performers in
the MACT floor pool--not just those with emissions below the average of
the best performers-- meet the promulgated standard (highest 30-day
average in MACT pool is 41.63 lb/MM tons clinker; the standard is 55
lb/MM tons clinker (30-day average). In addition, several additional
kilns, which are not in the pool of best performers, meet the
standards. For THC, all kilns in the pool of best performers meet the
promulgated standard (highest 30-day average in MACT pool is 5.68 ppmv;
the standard is 24 ppmv). In addition, seven additional kilns which are
not in the pool of best performers meet the standards. Indeed, nine of
the 11 kilns for which EPA has CEM data are meeting the promulgated
standards for THC. For PM, all six kilns in the MACT pool as well as
twelve kilns overall meet the promulgated 30-day standard even though
the measurements in the data base are stack tests (i.e., unlike for
mercury and THC, these are not averaged values).\9\ Virtually all kilns
in the MACT floor pool are meeting the HCl standard, although this is
largely the result of setting the standard at a level reflecting
analytic method quantitation limits.
---------------------------------------------------------------------------

    \9\ Development of The MACT Floors For The Final NESHAP For
Portland Cement. August 6, 2010.
---------------------------------------------------------------------------

    Commenters presented virtually no quantified data that floor plants
are unable to meet the standards. See National Association of Metal
Finishers v. EPA, 719 F. 2d 624, 649 (3d Cir. 1983) (unquantified
assertions are entitled to little if any weight). Rather, their
comments (comment 2845 at Table 1, echoed by many other industry
commenters) provided narrative descriptions purporting to demonstrate
that floor plants would not be able to achieve the standards.\10\ In
those instances where commenters provided actual data on these plants'
performance, EPA took the information into account in developing the
final standards. Indeed, EPA adjusted all of the standards based on
actual data presented. However, EPA is not willing to act on pure
supposition and conjecture regarding variability, particularly in the
face of record information indicating that not only all floor plants
but a number of additional plants are already meeting the promulgated
standards.
---------------------------------------------------------------------------

    \10\ For example, the commenter asserted, without providing
support, that for the floor kilns the standards were ``achieved in
practice, but not under foreseeable operations''; ``achieved in
practice based on limited stack tests''; ``data shows that proposed
standard was not achieved in practice when malfunction emission
[sic] are included in compliance determination'' (although no such
data were provided to EPA).
---------------------------------------------------------------------------

c. Mercury Limits for Kilns
    i. Floor Determination. We proposed mercury emissions limits of 43
lb/million (MM) tons clinker for existing sources and 14 lb/MM tons
clinker for new sources. The proposed floor was based on 30 days of
data on all kiln inputs for 89 kilns. See 74 FR at 21142-43. For all
kilns but the five equipped with wet scrubbers, emissions were assumed
to equal the total mass of mercury fed to each kiln. Scrubber-equipped
kilns were considered to emit all mercury minus an assumed amount
representing the average performance of the wet scrubbers. For kilns
that waste cement kiln dust (CKD), the mercury component of the CKD was
subtracted from inputs to calculate emissions. Id. By conducting a
total mass balance for mercury and then assuming that all mercury
inputted is emitted (minus conservatively estimated removals for
scrubber usage and dust wastage), EPA made a near worst case assumption
as to kilns' mercury emission levels. The kilns were then ranked from
best to worst based on the extrapolated mercury emissions, normalized
to clinker production. EPA further proposed that no beyond the floor
standard was appropriate for either existing or new sources. Id. at
21149.
    Since proposal we received updated data on certain kilns' raw
materials usage and mercury content \11\ and used that data to revise
our average mercury emissions estimates from the best performing kilns
at proposal.\12\ We have also revised upward the floor kilns' projected
emissions based on their reasonably estimated intra-quarry variability
(explained further below). As a result, estimated emissions from these
kilns increased, and one of the kilns in the group of sources used to
set the existing source floor is no longer one of the best performing
kilns. At proposal, the average mercury emissions of the top 12 percent
of the kilns was 27.4 pounds per million (lb/MM) tons clinker, and the
average emissions of the best performing source were 13.4 lb/MM ton
clinker. After revising our mercury emissions estimates, the averages
were 32 and 14 lb/MM tons clinker, respectively, as shown in Table 2.
---------------------------------------------------------------------------

    \11\ See Portland Cement Association Comments on the NESHAP-
Proposed Rule (Docket Number: EPA-HQ-OAR-2002-0051) (September 4,
2009) at pp. 31-35.
    \12\ Development of The MACT Floors For The Final NESHAP For
Portland Cement, August 6, 2010.

                       Table 2--Mercury MACT Floor
------------------------------------------------------------------------
                                                      Mercury emissions
                     Kiln code                         (lb/MM ton feed)
------------------------------------------------------------------------
1589...............................................                8.48
1650...............................................                9.53
1315...............................................               15.26
1302...............................................               15.28
1248...............................................               16.63
1259...............................................               21.33
1286...............................................               22.65
1594...............................................               25.23
1435...............................................               25.51
1484...............................................               25.51
1364...............................................               25.91
------------------------------------------------------------------------
                          MACT--Existing Kilns
------------------------------------------------------------------------
Average: lb/MM tons feed (lb/MM tons clinker)......        19.21 (31.7)
Total variance.....................................               272.3

UPL: lb/MM tons feed (lb/MM tons clinker)..........         32.8 (54.1)
------------------------------------------------------------------------
                             MACT--New Kilns
------------------------------------------------------------------------
Average: lb/MM tons feed (lb/MM tons clinker)......         8.48 (14.0)
Total variance.....................................                35.2
UPL: lb/MM tons feed (lb/MM tons clinker)..........         12.3 (20.3)
------------------------------------------------------------------------

    As noted above, we are taking into account operating variability of
the best performing kilns, or in the case of new source MACT the single
best controlled kiln, in assessing their performance (i.e., both in
determining which performers are best, and calculating what their
performance is). When we calculated the UPL with 99 percent confidence
for the best performing sources (or in the case of new source MACT the
best controlled single source), we calculated a mercury floor of 55 lb/
MM tons clinker for existing sources and 21 lb/MM tons clinker for new
sources. We chose a 30-day averaging period for the mercury emission
limit. As noted above, the use of a 30-day average (as opposed to
hourly or daily averages) tends to reduce variability, and also best
reflects the nature of the data from which the floor was derived and
assures that several operating cycles of raw mill on and off are
included in each average. Id. at 21144.
    Industry commenters stated that we should account for additional
sources of variability in this floor determination, namely intra-quarry
variability and variability of the mercury content in local coals which
kilns could utilize. As explained below, beyond those situations where
commenters documented that sources actually used inputs with greater
mercury content than used during the 30-day test period (see note 11
above), or where further intra-quarry mercury variability could
reasonably be estimated, we did not do so.
    EPA is of course aware that limestone quarries are immense, and are
customarily used from periods of 50 to 100 years. Taking the average of
30 days of sampling data from one part of the quarry would not
necessarily encompass all of the different mercury levels throughout
the quarry.
    Although industry commenters originally raised the issue of long
term intra-quarry variability during the initial May 2007 30-day data
collection, no plant chose to perform additional sampling and analysis
of their raw materials and feed that would have allowed this issue to
be directly addressed. Certain industry commenters did point, however,
to data from the 30-day sampling effort as providing useful information
on potential intra-quarry mercury variability of the two best
performers. The data come from 30-day sampling conducted at four
sources (three of which are located at a single facility), which all
quarry limestone from a common geologic limestone formation.\13\ All
six kilns (the two floor kilns, and the other four kilns in the
immediate vicinity) are in the same city and within 9 miles of each
other. It is a reasonable assumption that variability of mercury levels
(as opposed to mercury levels themselves) across this formation are
substantially the same and therefore that the variability of mercury
levels in the two best performers' quarries can be adjusted to reflect
the variability seen in the other quarries which are part of the common
geologic formation. See Brick MACT, 479 F. 3d at 881-882 (EPA may look
at performance of sources which are not among the best in estimating
variability of best performers if there is a demonstrated relationship
between the two).
---------------------------------------------------------------------------

    \13\ Memorandum. Intra-quarry Variability Estimate, July 21,
2010.
---------------------------------------------------------------------------

    EPA further applied these estimates of intra-quarry variability to
the mercury data for the other best performing kilns (i.e., applied the
same RSD to the other best performing sources). EPA did so to more
robustly characterize long-term variability of these sources' quarries'
mercury levels. The fact that intra-quarry variability of the two
lowest emitting sources increased somewhat after examination with other
quarries in the common geologic formation confirms that there can be
further variability. Since the intra-quarry variability comes from
quarries servicing the two lowest emitting kilns, EPA would not expect
intra-quarry variability to be lower for the other best performing
sources. In no other instance did commenters provide data that we could
use to determine intra-quarry variability for kilns in the MACT floor
pool.\14\
---------------------------------------------------------------------------

    \14\ For example, one industry commenter submitted core
(unground, unprocessed) samples from its quarry which samples
differed in mercury content by approximately one order of magnitude.
This facility is not a best performer, the samples are single
measurements (rather than 30-day measurements or some longer
duration), and (unlike the 30-day measurements used as the basis for
the standard) have not been processed (i.e., passed through the
quarry crushers and mixed in the storage pile which would tend to
make the material more homogeneous). Therefore, these data are not
comparable to the data used to set the MACT floors.
---------------------------------------------------------------------------

    Commenters also maintained that because cement kilns can burn
different types of coal, variability of coal mercury content needs to
be factored into estimates of sources' performance. Commenters
maintained that they obtained coal from a ``local market'' and so might
eventually use any coal from that market. The comments did not further
link coal to individual mines or to other particularized sources.
Commenters appear to be asking for an upward adjustment of the MACT
floors based on coal they might potentially use but never had used. EPA
believes that allowing for any inputs that might conceivably be used in
the future, including from sources in an area which a source has never
used to date, goes beyond a reasonable estimate of performance over
time and invites inflated estimates of variability based only on
hypothesized possibilities, not on actual behavior.\15\ EPA not only
does not believe such methodology is a reasonable means of calculating
sources' achieved performance, but also believes that such an approach
creates a perverse incentive to build in compliance margins based on
seeking out more polluted inputs.
---------------------------------------------------------------------------

    \15\ The situation differs from use of limestone from a
proprietary quarry. Not only have sources used the quarry in the
past but will necessarily continue to do so in the future.
---------------------------------------------------------------------------

    For example, the price of lower mercury coal may increase as a
result of this rule (it may be more desirable as a means of keeping
mercury emissions low), so plants may seek out higher mercury coal
which they otherwise have never used. This type of volitional activity
does not seem to be within the ambit of normal variability of process
inputs. In addition, facilities do have choices for coal. As noted in
the comments, some facilities obtain coals from several States, while
others appear to limit themselves to more local areas. However, coal is
a commodity that can be transported long distances to fuel utility
boilers. Therefore, we believe that a facility should have sufficient
coals available that they would not be compelled to use a higher
mercury coal just because it happens to be near the plant.
ii. Decision Regarding Whether To Create a Subcategory Based on
Limestone Mercury Content
    EPA may create subcategories which distinguish among ``classes,
types, and sizes of sources.'' CAA section 112(d)(1). EPA reads this
provision to provide the Agency with discretion to subcategorize,

and EPA may exercise that discretion if sources are rationally
distinguishable due to some difference in class, type or size. See
Lignite Energy Council v. EPA, 198 F. 3d 930, 933 (DC Cir. 1999) (``EPA
is not required by law to subcategorize--section 111[b][2] merely
states that `the Administrator may distinguish among classes, types,
and sizes within categories of new sources' '' (emphasis original)).
Moreover, as we noted at proposal, ``normally, any basis for
subcategorizing must be related to an effect on emissions, rather than
to some difference among sources which does not affect emissions
performance.'' 74 FR at 21145. EPA may also exercise this discretion on
a pollutant-specific basis, since the difference in class, type or size
may only have practical significance for certain HAP. In this final
rule, EPA carefully considered the possibility of creating different
subcategories of cement kilns with respect to mercury emissions.
    The subcategorization possibilities for mercury which we considered
and rejected at rule proposal were the type of kiln, presence of an
inline raw mill, practice of wasting cement kiln dust, total mercury
inputs, or geographic location. See 74 FR 21144-21145. We likewise
reject these bases in this final rules for the reasons already stated.
    At proposal we also considered subcategorizing by the mercury
concentration of the limestone in the kiln's proprietary quarry. We did
not propose to create this type of subcategory, and also choose not to
do so in this final rule.
    As we explained at proposal, the facts do not indicate sharp
disparities in limestone mercury content that readily differentiate
among types of sources for most of the facilities for which we have
data, and thus do not support this subcategorization approach for the
majority of the facilities. See Figure 1 showing a gradual continuum of
mercury concentrations in limestone for all but two outlying plants.
[GRAPHIC] [TIFF OMITTED] TR09SE10.001

Industry commenters who supported creating a separate subcategory for
the two highest mercury emitting sources based on limestone mercury
content agreed with this assessment. Thus, EPA sees no technical
justification to subcategorize by limestone quarry mercury content for
the majority of the source category.
    However, as also shown in Figure 1, there is a sharp disparity for
two kilns which have the highest quarry mercury contents. These
sources' mercury emissions are also disproportionately higher than all
other cement kilns', and are related almost entirely to the limestone
mercury content, not to mercury content of other inputs. Commenters who
supported subcategorization by quarry mercury levels recommended that
EPA create a separate source category for these two kilns based on
their uniquely high quarry mercury contents.
    If we were to set a separate subcategory for these two kilns, we
determined that the floor level of control would be approximately 2100
lb/MM tons clinker. Due to the high level of this floor, we evaluated a
beyond-the-floor option of 85 percent reduction in emission for the
highest emitting kiln. This level would represent the highest level of
mercury control believed achievable for the highest emitting facility
based on test data on a pilot mercury control system for that
facility.\16\ This level of control would result in an emissions limit
of

approximately 500 lb/MM tons clinker. This level is over 10 times the
level that will be required for all other kilns, and even exceeds every
other kiln's uncontrolled mercury emissions levels which range from 20
to 400 lb/MM tons clinker.
---------------------------------------------------------------------------

    \16\ Letter, C. Lesslie, Ash Grove Cement to P. Tsirigotis, U.S.
EPA, April 22, 2010.
---------------------------------------------------------------------------

    Mercury in the air eventually settles into water or onto land where
it can be washed into water. Once deposited, certain microorganisms can
change it into methylmercury, a highly toxic form that builds up in
fish, shellfish and animals that eat fish. Fish and shellfish are the
main sources of methylmercury exposure to humans. Methylmercury builds
up more in some types of fish and shellfish than in others. The levels
of methylmercury in fish and shellfish depend on what they eat, how
long they live and how high they are in the food chain. Mercury
exposure at high levels can harm the brain, heart, kidneys, lungs, and
immune system of people of all ages. Research shows that most people's
fish consumption does not cause a health concern. However, it has been
demonstrated that high levels of methylmercury in the bloodstream of
unborn babies and young children may harm the developing nervous
system, making the child less able to think and learn.\17\ Heightened
concern for mercury's toxic effects is reflected directly in the
structure of section 112 of the Act. Mercury is one of the pollutants
identified for MACT-level control under the CAA's air toxics provision
even (in most instances) when emitted by area sources (see CAA section
112(c)(6)).
---------------------------------------------------------------------------

    \17\ For more information see http://www.epa.gov/mercury/
about.htm.
---------------------------------------------------------------------------

    Thus, creating a high-mercury subcategory for two kilns based on
limestone mercury content would result in standards allowing emissions
of 500 lb/MM tons of clinker. Based on 2008 production rates, this
would allow 1,020 pounds of mercury emissions per year from the
potential two-plant subcategory. To put this in perspective, the rest
of the industry (92 plants) would be allowed to emit 1,012 pounds tons
of mercury per year (again based on 2008 production rates), and the two
high-emitting plants would be allowed to emit 1,020 pounds per year.
This would result in a doubling of mercury emissions from this source
category after the application of MACT. Moreover, national mercury
emissions for industrial sources are approximately 50 tpy.\18\ That
would mean that these two sources alone would constitute 1 percent of
the industrial mercury emissions for the U.S. EPA believes it is a
reasonable exercise of discretion not to create a subcategory, where,
as here, doing so would allow on-going emissions of a
disproportionately high volume of a high-toxicity pollutant.
---------------------------------------------------------------------------

    \18\ Mercury Emission in the U.S. by Source Category 1990 to
1993, 2002, and 2005. http://cfpub.epa.gov/eroe/
index.cfm?fuseaction=detail.viewMidImg&ch=46&lShowInd=0&subtop=341&lv
=list.listByChapter&r=188199.
---------------------------------------------------------------------------

    Due to mercury's high toxicity and the extremely high mercury
emissions that would result, the Administrator is thus not exercising
her discretion to subcategorize in setting the final mercury emissions
limit. In light of this decision, it is unnecessary for EPA to address
the further question of whether subcategorizing by raw material content
of proprietary quarries is permissible under section 112 of the Act.
    Although the Agency has concluded that it is reasonable to set the
same mercury standard for all cement kilns, we acknowledge the unique
challenges that the highest emitting sources may face in meeting the
reductions within the regulatory compliance timeline. In particular, as
discussed at length above, the two highest emitting kilns--the kilns
located in Durkee and Tehachapi--have unusually high levels of mercury
in their proprietary limestone quarries, which, as typifies this
sector, are located proximate to kiln operations. The mercury content
of source material is the key factor in the high levels of emissions
experienced at these kilns and a complicating consideration in their
ability to achieve compliance in a timely manner.
    We also recognize that this challenge presents a unique opportunity
to achieve substantial reductions in this naturally occurring,
persistent, and widespread contaminant in an amount and on a schedule
that exceeds what will be required in the final rule. The Agency
believes that the two sources in question may be able in the near term
to install aggressive controls, including activated carbon injection,
that would result in dramatic near term reductions in mercury emissions
(as much as 90 percent or two tons of mercury emissions in the first
two years of operation). If they were to do so, these sources would
emit substantially less mercury in the next few years than the
alternative of allowing these facilities to continue to emit at current
levels for three additional years, as would otherwise be the case. This
would be a very substantial reduction in emissions of this pollutant.
Annual emissions of mercury from all sources (not just cement kilns)
are estimated to be 50 tpy,\19\ and emissions from the entire source
category are approximately 7.5 tons per year,\20\ so that a two ton
reduction is a substantial reduction of mercury emissions.
---------------------------------------------------------------------------

    \19\ Mercury Emission in the U.S. by Source Category 1990 to
1993, 2002, and 2005. http://cfpub.epa.gov/eroe/
index.cfm?fuseaction=detail.viewMidImg&ch=46&lShowInd=0&subtop=341&lv
=list.listByChapter&r=188199.
    \20\ \\ Summary of Environmental And Cost Impacts For Final
Portland Cement NESHAP And NSPS August 6, 2010.
---------------------------------------------------------------------------

    We understand that one of the two high emitting kilns has already
installed activated carbon injection, but that its performance could be
further optimized. See 74 FR 21148. The other kiln would have to
install activated carbon injection and both kilns would need to install
dust shuttling. The net benefit to the environment and public health
would extend a number of years beyond the MACT compliance deadline.
    If the Durkee and Tehachapi kilns were willing to make a near term
reduction (e.g., 90 percent) in their mercury emissions significantly
before the compliance date in the rule, the Agency would consider
providing these kilns a compliance schedule that extends beyond the
three to four years specified in this rule. The purpose of such an
approach would be to provide a substantial net benefit to the
environment; therefore ultimate compliance with the MACT standard would
need to be by a date that ensures the long term emissions from these
sources would be significantly lower than their emissions from meeting
the standard on the schedule in the rule. Given the nature of mercury
and the additional reductions that could be obtained, the Agency is
interested in exploring this concept.
    Finally, EPA notes that the same early reduction opportunities for
mercury do not appear to exist for the rest of the Portland cement
industry. It typically takes on the order of three years to install
activated carbon injection technology. One of the high mercury plants
has recently completed installation of ACI and has just commenced full
scale operation of the kiln with ACI installed. The other kiln faces
fewer installation barriers than other kilns. This is because the
company has tested carbon injection and dust shuttling on one of its
other kilns, and is already using dust shuttling to reduce emissions at
another kiln, and is therefore better positioned to rapidly install
controls after one year. To our knowledge, these circumstances are not
applicable to the rest of the Portland cement source category, and
could not even be duplicated at all the other facilities owned by these
companies due to limitations in

infrastructure available to design and build these systems.
iii. Beyond the Floor Determinations for Mercury
    We are basing the final mercury standard on the floor level of
control. When we establish a beyond the floor standard we typically
identify control techniques that have the ability to achieve an
emissions limit more stringent than the MACT floor. Under these final
amendments, most existing kilns would have to have installed both a wet
scrubber and activated carbon injection (ACI) for control of mercury,
HCl and THC.\21\ To achieve further reductions in mercury beyond what
can be achieved using wet scrubber and ACI in combination, the
available options would include closing the kiln and relocating to a
limestone quarry having lower mercury concentrations in the limestone,
transporting low-mercury limestone in from long distances, switching
other raw materials to lower the amount of limestone in the feed,
wasting CKD, and installing additional add-on control devices. These
options were discussed at proposal, and were rejected as either
technically infeasible or not cost-effective. Consideration of non-air
quality impacts and energy requirements do not change this conclusion.
See 74 FR at 22249-50. We received no comments that would cause us to
change that determination.
---------------------------------------------------------------------------

    \21\ Summary of Environmental and Cost Impacts of Proposed
Revisions to Portland Cement NESHAP (40 CFR Part 63, subpart LLL),
April 15, 2009.
---------------------------------------------------------------------------

    We did receive one comment from an environmental group requesting
EPA explore fuel switching as a beyond the floor option. However, EPA
thoroughly explored fuel switching as a control option in the 2006
rulemaking and determined that there were problems with fuel
availability and the costs were prohibitive. See 70 FR 72340. EPA is
not presently aware of facts that would justify a different approach in
this final rule.
    As a result of these analyses, we determined that, considering the
technical feasibility and costs, there is no reasonable beyond the
floor control option, and the final mercury emission limit is based on
the MACT floor level of control.
c. THC Limits for Kilns and Raw Material Dryers
    The limits for existing and new sources in this final rule apply to
both area and major sources. As noted earlier, we have applied these
limits to area sources consistent with CAA section 112(c)(6).
    i. Floor Determination. EPA proposed THC emissions limits of 7 and
6 parts per million by volume dry (ppmvd) for existing and new sources
respectively for both cement kilns and raw material dryers. The
existing source standard was based on the performance of the best
performing 12 percent of cement kilns for which we had THC CEMS data.
At proposal we requested comment on the issue of whether or not we
should base the existing source floor on the best performing five
kilns, rather than on the best performing 12 percent (two kilns).
Industry commenters supported the use of the best five kilns stating
that this would be in keeping with what appeared to be the intent of
Congress that five kilns should be the minimum number of sources on
which to set an existing source floor. However, other commenters noted
that a plain reading of the statute is that when the source category
has 30 or more sources, the top performing 12 percent for which the
Administrator has data must be used, even if this results in less than
five facilities due to lack of available data. In this final rule we
are reaffirming our decision at proposal to use the best performing 12
percent rather that the best performing five facilities because we
believe this result to be unavoidably compelled by the literal language
of the statute.
    At proposal we set the emissions limit based on the 99th percentile
of the available data. As a result of new data received after the
comment period, we recalculated the averages of the kilns for which we
had CEMS data and selected the best performing two kilns (12 percent of
15 total kilns) based on their average emissions. See Calculations of
Floors for Final Portland Cement NESHAP dated August 6, 2010. Because
these were large data sets (688 and 274 readings), we directly
calculated the 99th percentile of the 30-day averages to determine the
MACT floor which is 24 ppmvd.\22\ This is shown in Table 3.
---------------------------------------------------------------------------

    \22\ In other words, as noted above, EPA possesses sufficient
THC data that it is not necessary to estimate variability by use of
the UPL equation. Rather, variability is calculated directly from
the THC data set comprised of the two lowest emitting sources.

---------------------------------------------------------------------------

[GRAPHIC] [TIFF OMITTED] TR09SE10.002

    For new sources, we analyzed the data from the kiln with the lower
numeric average to determine the 99th percentile of its performance.
The result of this analysis was also a 24 ppmvd standard because this
kiln had more variability (although a lower average performance) than
the other kiln in the data set. This emission limit is based on a
concentration measured dry, corrected to 7 percent oxygen and a 30-day
average measured using a CEM.
    ii. Additional THC data received too late to be considered in this
rulemaking. In addition to the THC CEMS data just discussed, we
received another set of THC CEMS data from the Portland Cement
Association (PCA). These data were not submitted to EPA until mid-June
2010, virtually too late for any consideration, much less considered
analysis. This set consisted of THC CEMS data collected over periods
ranging from 31 to 90 days for additional kilns not in the data base
discussed above, as well as additional data from some of the kilns
already in our data base. These additional data increased the total
number of kilns with THC CEMS data to 30 kilns. The PCA also provided a
floor analysis on this data set and recommended THC emissions limits.
The data set as presented by PCA is shown in Table 4.

                 Table 4--Portland Cement Association: Determination of Size of Best Performing Pool for Proposed Sub-Categories for THC
                                                             [Mid-June 2010 data submission]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Procedure for selecting pool of best performing kilns
                                                             Kilns for which ---------------------------------------------------------------------------
              Sub category                 Estimated U.S.       data are                      Existing units
                                             population         available    -----------------------------------------------          New units
                                                                                Rule                 Pool size
--------------------------------------------------------------------------------------------------------------------------------------------------------
Major Non-Commingled Kilns..............              > 30                17  Best 12%...................                 3  Best 1.
Major Commingled Kilns..................              < 30                 7  Best 5.....................                 5  Best 1.
                                                                             ---------------------------------------------------------------------------
Area Kilns..............................              < 30                 6                           Work Practices Standard.
--------------------------------------------------------------------------------------------------------------------------------------------------------

    In this analysis, the PCA proposed two subcategories: Kilns where
the coal preparation mill exhaust is comingled with the kiln exhaust,
and kilns where the coal preparation mill has a separate stack. The PCA
maintains that subcategories are needed because emissions for the coal
preparation mill (which are believed to be chiefly methane from the
coal) will, all other things being equal, elevate the THC emissions of
the kiln exhaust. See also 74 FR at 21152. The PCA recommended floors
are shown in Tables 5 and 6 below:

   Table 5--Alternative MACT Floors for THC Major Non-Commingled Kilns
------------------------------------------------------------------------
                                                  Existing
                                                   units      New units
                                                   (ppm)        (ppm)
------------------------------------------------------------------------
99th Percentile...............................           30           11
99.9th Percentile.............................           36           12
------------------------------------------------------------------------

     Table 6--Alternative MACT Floors for THC Major Commingled Kilns
------------------------------------------------------------------------
                                                  Existing
                                                   units      New units
                                                   (ppm)        (ppm)
------------------------------------------------------------------------
99th Percentile...............................           70           17
99.9th Percentile.............................           80           20
------------------------------------------------------------------------

    However, the PCA MACT analysis suffers from one major deficiency
because it excludes area sources from

the MACT floor analysis, and assumes a work practice for these sources.
As previously noted, THC emissions serve as surrogates for POM and PCB
emissions. CAA section 112(c)(6) requires EPA to list, and to regulate
under standards established pursuant to CAA section 112(d)(2) or
(d)(4), categories of sources accounting for not less than 90 percent
of emissions of these HAP standards established under CAA section
112(d)(2) must reflect the performance of MACT. Again, as explained
above, EPA has long since determined that area source cement kilns' THC
emissions must be controlled under CAA section 112 (d)(2) or (d)(4) in
order to satisfy the 90 percent requirement. Therefore, these area
sources should have been included in the MACT floor analysis.
    If this error in the floor analysis is corrected, the MACT floor
for the kilns with comingled exhaust would be unchanged from the PCA
analysis of 70 ppmvd for existing and 17 ppmvd for new (assuming the
statistical calculations were done correctly).
    However, this estimate is premised on the assumption that there are
less than 30 kilns in this subcategory (so that 5 sources would be used
to establish the floor). That assumption is based on data provided in
the PCA report that indicated, of the 87 kilns that provided data to
PCA on their coal preparation stack configurations, 13 had comingled
exhaust. If there are actually 30 or more kilns with this
configuration, the MACT floor would have to be based on the best
performing 12 percent of 8 kilns (the 7 major source comingled kilns
plus one area source comingled kiln) which would be one kiln, Lehigh at
Union Bridge. If one kiln is used for the existing source floor, the
existing source MACT limit would be 17 ppmvd using the 99th percentile.
The estimate of 26 versus 30 or more sources causes a high level of
uncertainty in this analysis.
    For sources that do not comingle the exhaust, the floor would
appear to be approximately 13 ppmvd when the area sources are included
in the analysis. This is also lower than the floor calculated from the
long term data set out above (and would result in a standard roughly 50
percent more stringent than that which EPA is adopting).
    The PCA analysis also recommended a separate subcategory for kilns
with high limestone outgassing based on the information shown below:
[GRAPHIC] [TIFF OMITTED] TR09SE10.003

    The limestone outgassing factor is determined by heating a sample
of the limestone from the kiln's proprietary quarry to determine the
potential for THC emissions based on the amount and types of organic
materials present. The premise here is basically the same as previously
discussed for subcategorization by limestone mercury content when
setting mercury emissions limits, because the kiln is tied to its
limestone quarry. The subcategory proposed was for sources with THC
outgassing >= 65 mg/kg. The recommended THC emissions limits for this
subcategory were 170 and 62 ppmvd for new and existing sources
respectively. This analysis, however, suffers from the same defect
previously discussed in that for a subcategory with only three sources
where we have data, the best performing 12 percent would be one kiln,
so the actual limit for new and existing would be 62 ppmvd. We rejected
this option because it suffers from the same defects as
subcategorization by limestone mercury content. First, the choice of
high versus low organics appears arbitrary. A level between 75 and 175
could just as easily have been chosen. The selection of 65 appears to
be an attempt to move the high THC emitting facility into a subcategory
with a high limit. Second, subcategorizing in this manner could result
in situations where a few facilities would be allowed to emit at levels
well above the remainder of the sources in this source category. Third,
although the two kilns with the highest outgassing limestone appear to
be outliers (similar to the two facilities with unusually high
limestone mercury contents), we do not have data on a majority of the
kilns (as we do with mercury) and it is possible that if we had more
data, the two facilities that appear to be outliers would be part of a
gradual continuum, which would mean the level we chose to separate high
and low outgassing limestone would be mistaken.
    We also considered combining all the THC CEMS data (the more recent
PCA data, data used at proposal, and data received during the comment
period which would create a data set of 34 kilns). The results of this
analysis was a floor (based on the 99th percentile of the data) of 24
ppmvd for existing sources (the same standard adopted in

the final rule) and 3 ppmvd for new sources (more stringent than the
new source standard in the final rule). Given the short time available
to review the PCA data, the uncertainty concerning the actual size of
one of the subcategories, the fact that these data would not in our
view significantly change the levels of the standard for most kilns,
and the concerns we have with subcategorization by limestone organic
outgassing potential, we conclude that there is no compelling reason to
change our floor determination based on this new information, which
again was submitted only days before the final rule requirements had to
be determined in order to meet the court ordered deadline for this
rule.
    iii. Beyond the floor determination. At proposal we evaluated
several practices and technologies that are available to cement kilns
to control emissions of organic HAP at a level beyond the floor. 74 FR
at 21152. These practices include raw materials substitution, ACI
systems and limestone scrubber and regenerative thermal oxidizer (RTO).
We rejected each of these alternatives based on technical limitations
or poor cost- effectiveness. Consideration of non-air quality impacts
and energy support this determination as well (RTOs in particular being
associated with appreciable energy penalties). 74 FR at 21152. We
received no comments that have caused us to change that proposed
decision. Therefore, we are choosing the floor level of control for the
final THC emissions limit.
    iv. Standards for THC. We are establishing the emissions limit for
THC at the floor level of control. In addition, because the final
existing source standard will be more stringent than the new source
standard of 50 ppmvd for greenfield new sources contained in the 1999
final rule, we are also removing the 50 ppmvd standard for both kilns
and raw material dryers.
    EPA proposed an alternative floor for non-dioxin organic HAP, based
on measuring the organic HAP itself rather than the THC surrogate. This
equivalent alternative limit would provide additional flexibility in
determining compliance, and it would be appropriate for those cases in
which methane and ethane comprise a disproportionately high amount of
the organic compounds in the feed because these non-HAP compounds could
be emitted and would be measured as THC. At proposal we determined that
organic HAP averaged 24 percent of the THC. Since proposal we have
reevaluated these data and recalculated an average organic HAP
concentration of 35 percent. Based on this percentage, and the fact
that the THC emission limit is now 24 ppmvd, we are promulgating an
alternative organic HAP limit of 9 ppmvd, corrected to 7 percent oxygen
(or 19 percent oxygen for raw material dryers), for new and existing
sources. The specific organic compounds that will be measured to
determine compliance with the alternative to the THC limit are benzene,
toluene, styrene, xylene (ortho-, meta-, and para-), acetaldehyde,
formaldehyde, and naphthalene. These were the organic HAP species that
were measured along with THC in the cement kiln emissions tests that
were reviewed. Nearly all of these organic HAP species also were
identified in an earlier analysis of the organic HAP concentrations in
THC in which the average concentration of organic HAP in THC was 35
percent.\23\
---------------------------------------------------------------------------

    \23\ Summary of Organic HAP Test Data. August 6, 2010.
---------------------------------------------------------------------------

    The alternative standard will be based on organic HAP average
concentration of organic HAP in THC was 35 percent.\24\ The alternative
standard will be based on organic HAP emission testing and concurrent
THC CEMS measurements that will establish a site specific THC limit
that will demonstrate compliance with the total organic HAP limit. The
site specific THC limit will be measured as a 30 day rolling average.
---------------------------------------------------------------------------

    \24\ Ibid.
---------------------------------------------------------------------------

    iv. THC Emissions from Raw Material Dryers. As we noted at
proposal, some plants may dry their raw materials in separate dryers
prior to or during grinding. See 74 FR at 21153; see also 63 FR at
14204. This drying process can potentially lead to organic HAP and THC
emissions in a manner analogous to the release of organic HAP and THC
emissions from kilns when hot kiln gas contacts incoming feed
materials. The methods available for reducing THC emissions (and
organic HAP) is the same technology described for reducing THC
emissions from kilns and in-line kiln/raw mills. Based on the
similarity of the emissions source and controls, we proposed to set the
THC emissions limit of materials dryers at the same levels as the
kilns.
    Commenters noted that stand alone raw materials dryers have higher
gas flows relative to the amounts of fuels burned. This results in
higher oxygen concentrations, typically as high as 19 percent. They
also noted that raw material dryers may have higher THC and lower HAP
emissions because raw materials dryers operate at lower temperature
than kilns (since the dryer only needs to operate at the temperature
needed to remove free water), and that the residence times for dryers
is considerably longer than for kilns.
    However, although we agree that the exhaust oxygen contents of raw
material dryers may be higher than occurs with a cement kiln, there are
reasons to believe that dryers actually emit less hydrocarbons than
kilns. Operating at lower temperatures, we would expect any
hydrocarbons that are emitted from dryers to be only those with the
highest volatility, and therefore that the potential for emissions of
organic HAP would be less for dryers than for kilns. However, the
longer residence times could tend to increase emissions. Therefore,
making any conclusions on the emission of dryers relative to kilns is
difficult. We also note that we are allowing dryers to also use the
alternative organic HAP emissions limit, so if the surmise that organic
HAP emissions are low relative to the cement kilns is correct, this
alternative should be very viable for these sources.
    In short, we received no data indicating that the same limit as for
kilns was infeasible, or that would otherwise allow us to set a
different THC emissions limit for raw materials dryers. Therefore, in
these final amendments we are setting the THC emissions limit at the
same level as the cement kiln's, which is 24 ppmvd measured as propane.
    However, because raw material dryers have high oxygen contents due
to their inherent operation characteristics (and not due to the
addition of dilution air), referencing the raw material dryer standard
to 7 percent oxygen would actually result in a more stringent standard
than for cement kilns. For example, given the typical oxygen contents
of kiln exhaust (7 to 12 percent), a kiln just meeting the THC limit of
24 ppmvd would have an actual stack measurement of approximately 16 to
24 ppmvd. If the raw material dryer standard is referenced to the same
oxygen level, they would have to meet a measured THC limit of
approximately 3 ppmvd. For this reason, we are referencing the oxygen
level of the standard for raw materials dryers to 19 percent oxygen,
which is the typical oxygen level found in the exhaust of these
devices.
d. Hydrochloric Acid Emissions From Kilns
    In the proposed rule we based the proposed HCl emission limit for
major sources on HCl data measured at 27 kilns using Method 321. The
data in ppmvd corrected to 7 percent oxygen (O2) were ranked
by emissions level and the top 12 percent (4 kilns) lowest emitting
kilns identified as best

performing existing sources. The calculated MACT floors were 2 ppmvd
and 0.1 ppmvd respectively.
    i. Floor Determination. Subsequent to proposal, we received
comments that indicated we had inappropriately (albeit inadvertently)
included certain natural area sources in the MACT floor analysis. We
have removed those natural area sources from the floor analysis. In
addition, many of the source tests were not actually EPA Method 321
tests; others lacked important quality assurance information. As a
result, we issued letters under CAA section 114 authority requiring
facilities that were major sources and that had previously submitted
data to retest their facilities. We used this new data set to calculate
a MACT floor. The data from the best performing three sources, as
determined by average emissions during the test, are shown below in
Table 7.

                         Table 7--HCl MACT Floor
------------------------------------------------------------------------
                                                           HCl emissions
                          Kiln                             (ppmvd at 7%
                                                                O2)
------------------------------------------------------------------------
1.......................................................            0.34
2.......................................................            0.44
3.......................................................            0.46
------------------------------------------------------------------------
                             MACT--Existing
------------------------------------------------------------------------
Average (Top 3).........................................            0.41
Variance................................................            0.02
UPL.....................................................            0.52
------------------------------------------------------------------------
                                MACT--New
------------------------------------------------------------------------
Average.................................................            0.34
Variance................................................            0.0
UPL.....................................................            0.34
------------------------------------------------------------------------

    However, these measurements are very close to the detection limit
for analytic method 321 actually calculated in the field for HCl--from
0.2 to 0.3 parts per million by volume (ppmv) as measured in the
stack.\25\ The expected measurement imprecision for an emissions value
occurring at or near the method detection level is in fact about 40 to
50 percent. This large measure of analytic uncertainty decreases as
measured values increase: Pollutant measurement imprecision decreases
to a consistent relative 10 to 15 percent for values measured at a
level about three times the method detection level. See American
Society of Mechanical Engineers, Reference Method Accuracy and
Precision (ReMAP): Phase 1, Precision of Manual Stack Emission
Measurements, CRTD Vol. 60, February 2001. Thus, if the value equal to
three times the representative method detection level were greater than
the calculated floor emissions limit, we would conclude that the
calculated floor emissions limit does not account entirely for
measurement variability.
---------------------------------------------------------------------------

    \25\ Memorandum. EPA Method 321 Detection Limits and Minimum
Quantification Limit, July 26, 2010.
---------------------------------------------------------------------------

    That is the case here with HCl. The calculated standard (not
accounting for the inherent analytical variability in the measurements)
is 0.52 ppm (see Table 7 above). In order to account for measurement
variability, we multiplied the highest reported minimum detection level
for the analytic method by a factor of three which results in a level
of 0.9 ppmv. This represents the lowest level that can be reliably
measured using this test method, and we therefore believe that it is
the lowest level we can set as the MACT limit taking the appropriate
measurement variability into account. Converting this level to a dry
basis at 7 percent oxygen results in a floor of 3 ppmvd for both new
and existing sources. As explained further below, we are using a CEM to
measure this standard, and it is a 30-day average.
    ii. Beyond the Floor Determination. At proposal we examined the use
of a packed bed scrubber, which was assumed to have a higher HCl
removal efficiency than the spray tower limestone scrubbers typically
used in this industry. Considering the high costs, high cost-
effectiveness and small additional emissions reduction (and adverse
cross-media impacts), we did not believe that a beyond-the-floor
standard for HCl is justified. We received no comment that would change
that decision. In addition, the current HCl floor limit is actually set
at the lowest level we believe can be accurately quantified by the
applicable test method. Therefore, a lower standard could not be
reliably quantified. For these reasons we selected the floor level of
control as MACT for HCl for major sources.
    iii. Compliance Mechanisms. As proposed, kilns equipped with wet
scrubbers may demonstrate compliance by means of stack testing at
intervals of 30 months, plus utilize continuous monitoring of specified
parameters. All other kilns are required to use a CEMS, with compliance
based on a 30-day rolling average. Although the underlying data were
obtained via stack tests, rather than with continuous monitors, EPA
believes that because the HCl standard is established at a level higher
than all measured values (to account for the inability to reliably
measure any lower standard) and measured based on 30-day averages, it
provides an ample compliance margin.
    iv. Determination not to Establish a Risk-Based Standard for HCl.
At proposal, EPA elected not to exercise its discretion under CAA
section 112(d)(4) and proposed a major source standard for HCl based on
MACT. The primary basis for not setting a health-based standard was
that setting a MACT standard for HCl not only controlled HCl but also
co-controlled other HAP (such as HF, Chlorine (Cl2), and
hydrogen cyanide (HCN)) and criteria pollutants yielding very
substantial environmental benefits. However, we also requested comment
on whether we had the legal authority to establish a standard for HCl,
and, if so, whether we should exercise our discretion to do so. 74 FR
at 21154. After considering comments, EPA has decided not to exercise
its discretion to establish a risk-based standard for HCl under CAA
section 112(d)(4), opting instead to promulgate a standard for HCl
based on the performance of MACT in this final rule. This section
discusses the basis for that decision.
    Setting technology-based MACT standards for HCl will result in
significant reductions in emissions of other pollutants, most notably
SO2, and would likely also result in additional reductions
in emissions of mercury, along with condensable PM, ammonia, and semi-
volatile compounds. The additional reductions of SO2 alone
attributable to the MACT standard for HCl are estimated to be 124,000
tons per year in the third year following promulgation of the proposed
HCl standard. These are substantial reductions with substantial public
health benefits. SO2 emissions are associated with a variety
of human health, ecosystem, and visibility effects. 75 FR at 35525-27
(June 22, 2010). Even more significantly, SO2 is also a
precursor to PM2.5. Reducing SO2 emissions also
reduces PM2.5 formation, human exposure, and the incidence
of PM2.5-related health effects, among them premature
mortality and cardiovascular and respiratory morbidity. See detailed
discussion of PM2.5 health effects in the text at Table 13
below.
    For these rules the SO2 reductions represent a large
fraction of the total monetized benefits from reducing
PM2.5, but it is not possible to isolate the portion if the
total monetized benefits attributable to the emission reductions of
SO2 resulting from the application of HCl controls. The
benefits models assume that all fine particles, regardless of their
chemical composition, are equally potent in causing premature mortality
because there is no clear scientific evidence that would support the
development of differential effects estimates by particle type.

    We estimate the number of premature mortalities avoided each year
due to the reductions in PM2.5 exposure attributable to this
standard to be in the thousands. RIA Table 6-3. We also estimate there
to be over 2800 instances of annual cardiovascular and respiratory
morbidity cases avoided, and hundreds of thousands of work loss days
avoided. Id. The monetized benefits just from premature mortality
avoided attributable to PM2.5 reductions from this standard
are estimated to be $7.4 billion to $18 billion at the three percent
discount rate and $6.7 billion to $17 billion at a seven percent
discount rate, nearly an order of magnitude higher than the rule's
estimated social costs. See Table 13 below. Although MACT standards may
directly regulate only HAPs and not criteria pollutants, Congress did
recognize, in the legislative history to section 112(d)(4), that MACT
standards would have the collateral benefit of controlling criteria
pollutants as well and viewed this as an important benefit of the air
toxics program.\26\ The EPA believes these health and environmental
benefits to be large and important and fully in keeping with the
paramount goal of the Clean Air Act ``to protect and enhance the
quality of the Nation's air'' (CAA section 101(b)(1)), and so is
adopting MACT standards for HCl.\27\
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    \26\ See S. Rep. No. 101-228, 101st Cong. 1st sess. at 172. EPA
consequently does not accept the argument that it cannot consider
reductions of criteria pollutants in determining whether to exercise
its discretion to adopt a risk-based standard under section
112(d)(4). There appears to be no valid reason that EPA must ignore
controls which further the health and environmental outcomes at
which section 112(d) of the Act is fundamentally aimed.
    \27\ We further note that HCl is not the only acid gas HAP
emitted by Portland cement plants. Hydrogen fluoride, HCN, ammonia,
and chlorine may also present and were not accounted for in the risk
analysis. Setting an HCl standard under 112(d)(2) and (3) allows the
Agency to also address these other HAPs as they are co-controlled by
wet scrubbers along with HCl.
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    Commenters from industry urged EPA to retain a risk-based standard
but did not challenge EPA's finding or quantification that there would
be these enormous health and environmental benefits to setting a
standard reflecting MACT to control HCl. The commenters nonetheless
urged EPA to retain a risk-based standard, noting that EPA had done so
in the predecessor to this rule and for other source categories, and
that HCl is a threshold pollutant within the meaning of CAA section
112(d)(4) so that there is a technical basis for such a standard. These
arguments do not persuade the Agency to forego the very significant
benefits just outlined. However, even if (contrary to the analysis just
set out) EPA were inclined to adopt a risk-based standard here, there
would be technical obstacles to doing so, as described at the final
part of this section.
    As we noted in the proposed rule, as a general matter, CAA section
112(d) requires MACT standards at least as stringent as the MACT floor
to be set for all HAP emitted from major sources. However, CAA section
112(d)(4) provides that for HAP with established health thresholds, EPA
has the discretionary authority to consider such health thresholds with
an ample margin of safety when establishing emission standards under
CAA section 112(d). This provision is intended to allow EPA to
establish emission standards other than technology-based MACT standards
in cases where a less stringent emission standard will still ensure
that the health threshold will not be exceeded, with an ample margin of
safety. In order to exercise this discretion, EPA must first conclude
that the HAP at issue has an established health threshold and must then
provide for an ample margin of safety when considering the health
threshold to set an emission standard. We discussed this issue at
length in the recent proposed Industrial Boiler MACT. See 75 FR at
32020-33 (June 4, 2010) (declining to propose a risk-based standard for
HCl emissions).
    The legislative history of section 112(d)(4) indicates that
Congress did not intend for this provision to provide a mechanism for
EPA to delay issuance of emission standards for sources of HAPs. The
legislative history also indicates that a health-based emission limit
under section 112(d)(4) should be set at the level at which no
observable effects occur, with an ample margin of safety. S. Rep. 101-
228 at 171-72. The legislative history further states that employing a
section 112(d)(4) standard rather than a conventional MACT standard
``shall not result in adverse environmental effects which would
otherwise be reduced or eliminated.'' Id.
    It is clear that EPA may exercise its discretionary authority under
112(d)(4) only with respect to pollutants with an established health
threshold. Where there is an established threshold, EPA has, in the
proposed rule on industrial boilers, interpreted section 112(d)(4) to
allow us to weigh additional factors, beyond any established health
threshold, in making a judgment whether to set a standard for a
specific pollutant based on the threshold, or instead follow the
traditional path of developing a MACT standard after determining a MACT
floor (75 FR 32030). In deciding whether to exercise its discretion for
a threshold pollutant for a given source category, EPA has interpreted
section 112(d)(4) to allow us to take into account factors such as the
following: The potential for cumulative adverse health effects due to
concurrent exposure to other HAPs with similar biological endpoints,
from either the same or other source categories, where the
concentration of the threshold pollutant emitted from the given source
category is below the threshold; the potential impacts on ecosystems of
releases of the pollutant; and reductions in criteria pollutant
emissions and other co-benefits that would be achieved via the MACT
standard--the decisive factor here. Each of these factors is directly
relevant to the health and environmental outcomes at which section 112
of the Clean Air Act is fundamentally aimed. If EPA does determine that
it is appropriate to set a standard based on a health threshold, we
must develop emission standards that will ensure the public will not be
exposed to levels of the pertinent HAP in excess of the health
threshold, with an ample margin of safety.
    Since any emission standard under section 112(d)(4) must consider
the established health threshold level, with an ample margin of safety,
in this rulemaking EPA has considered the adverse health effects of the
HAP acid gases, beginning with HCl. Research indicates that HCl is
associated with chronic respiratory toxicity. In the case of HCl, this
means that chronic inhalation of HCl can cause tissue damage in humans.
Among other things, it is corrosive to mucous membranes and can cause
damage to eyes, nose, throat, and the upper respiratory tract as well
as pulmonary edema, bronchitis, gastritis, and dermatitis. Considering
this respiratory toxicity, EPA has established a chronic reference
concentration (RfC) for the inhalation of HCl of 20 [mu]g/m\3\. (See
http:[sol][sol]www.epa.gov/ncea/iris/subst/0396.htm.) An RfC is defined
as an estimate (with uncertainty spanning perhaps an order of
magnitude) of a continuous inhalation exposure to the human population
(including sensitive subgroups \28\) that is likely to be without an
appreciable risk of deleterious effects during a lifetime. The IRIS
health assessment evaluated chronic non-cancer risks and did not
include an evaluation of carcinogenic effects (on which there are very
limited studies). As a reference value for a single pollutant, RfCs do
not reflect any

potential cumulative or synergistic effects of an individual's exposure
to multiple HAPs or to a combination of HAPs and criteria pollutants.
Similarly, an RfC evaluation does not focus on potential environmental
impacts.
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    \28\ ``Sensitive subgroups'' may refer to particular life
stages, such as children or the elderly, or to those with particular
medical conditions, such as asthmatics.
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    With respect to the potential health effects of HCl, we know the
following:
    1. Chronic exposure to concentrations at or below the RfC is not
expected to cause chronic respiratory effects;
    2. Little research has been conducted on its carcinogenicity. The
one occupational study of which we are aware found no evidence of
carcinogenicity;
    3. There is a significant body of scientific literature addressing
the health effects of acute exposure to HCl (California Office of
Health Hazard Assessment, 2008. Acute Toxicity Summary for Hydrogen
Chloride, http:[sol][sol]www.oehha.ca.gov/air/hot_spots/2008/
AppendixD2_final.pdf#page=112 EPA, 2001). However, we currently lack
information on the peak short-term emissions of HCl from cement kilns
which might allow us to determine whether a chronic health-based
emission standard for HCl would ensure that acute exposures will not
pose health concerns.
    4. We are aware of no studies explicitly addressing the toxicity of
mixtures of HCl with other respiratory irritants. However, many of the
other HAPs (and criteria pollutants) emitted by cement kilns also are
respiratory irritants, and in the absence of information on
interactions, EPA assumes an additive cumulative effect (Supplementary
Guidance for Conducting Health Risk Assessment of Chemical Mixtures.
http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=20533).
    Cement kilns also emit other acid gases along with HCl, including
chlorine (Cl2), HCN and hydrogen fluoride (HF), all of which
are HAPs. Like HCl, these HAP gases have established chronic health
thresholds below which they are not expected to pose any significant
risk of chronic respiratory effects, have no evidence to suggest that
they may pose carcinogenic effects, and have an established body of
literature regarding acute respiratory health effects. They are also
controlled during the process of controlling HCl emissions from cement
kilns using a wet scrubber. As such, their health impacts must be taken
into account when considering a health-based emission limit for HCl.
    In the 2006 final rule, EPA did not set any standard for HCl.\29\
The Agency reasoned that no further control was necessary for Portland
cement emissions of HCl because HCl is a ``health threshold pollutant''
and human health is protected with an ample margin of safety at current
HCl emission levels. 71 FR at 76527. Underlying this conclusion was
EPA's analysis of a tiered screening study of dispersion modeling of
cement facilities' worst-case and actual HCl emissions. This study was
conducted by the Portland Cement Association for about two-thirds of
operating U.S. cement plants. Dispersion modeling results were
evaluated against the RfC for HCl.\30\ The screening analysis involved
making conservative assumptions regarding HCl emission concentrations
and plants' operating conditions (greater concentrations than known to
be emitted and perpetual operation at maximum capacity). All plants in
the analysis, with five exceptions, had HCl levels well below a Hazard
Quotient (HQ) level of 1.0, the ratio of exposure (or modeled
concentration) to the health reference value or threshold level. The
remaining five plants in the analysis had HQ levels greater than 1.0
assuming maximum emissions, but less than 1.0 when their actual
emissions were used in the dispersion models. Id. at 76528-29.
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    \29\ Although the decision not to set a standard in 2006 was
based on the authority of section 112(d)(4), we note that the
statute in fact states: ``the Administrator may consider such
threshold level, with an ample margin of safety, when establishing
emission standards under this subsection.'' Section 112(d)(4),
emphasis added.
    \30\ In the previous study EPA also evaluated dispersion
modeling results against an acute exposure guideline level (AEGL)
below which acute effects would not be expected to occur. However,
even given the uncertainties mentioned for short term HCl emissions,
that analysis indicated that chronic effects would be of the most
concern.
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    At proposal of these amendments, recognizing that the 2006
determination was deficient, if for no other reason because it failed
to establish any emission standard whatever, EPA conducted its own
analysis to determine what numerical standard for HCl would be
necessary to at least assure that, for the sources in the controlled
category or subcategory, persons exposed to emissions of HCl would not
experience the adverse health effects on which the threshold is based.
In order to determine this level, in the proposed rule we conducted a
risk analysis of the same 68 facilities analyzed by PCA using a
screening level dispersion model (AERSCREEN). Using the site specific
stack parameters provided by the PCA and conservative meteorological
conditions (taken from the PCA analysis), the AERSCREEN modeling
predicted the highest long term ground level concentration surrounding
each facility, and used this concentration to back calculate the
highest allowable HCl emissions rate that could occur without exceeding
the allowable RfC. The results of this analysis indicated that an HCl
emission limit of 23 ppmv or less (an order of magnitude higher than
the MACT standard) would result in no exceedances of the RfC for HCl
for any of the facilities assessed.\31\
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    \31\ Derivation of a Health-Based Stack Gas Concentration Limit
for HCl in Support of the National Emission Standards for Hazardous
Air Pollutants from the Portland Cement Manufacturing Industry,
April 10, 2009.
---------------------------------------------------------------------------

    Based on further consideration, EPA now believes that the 2006 PCA
study and analysis has the following deficiencies. First of all, not
all cement plants were evaluated (the PCA study covered about two
thirds of the plants in the source category), and among those not
evaluated were cement plants with the most likelihood of posing risk at
ground level from HCl emissions due to use of positive pressure
baghouses with monovents or multiple short stacks. Secondly, the
analysis did not consider the impacts of the co-emitted acid gases, an
important consideration in determining an ample margin of safety. In
addition, no data were provided, nor do we have data, on other
pollutants in the vicinity of these cement facilities, or background
concentration data for HCl to determine cumulative impacts of HCl
emissions for these facilities.\32\ EPA's analysis of 2009 could not
improve on the PCA study, given the lack of robust emissions data for
Cl2, HF, and HCN, and the lack of any additional data for
the cement kilns not included in the original study. As a result, EPA
cannot ensure that the resulting derivation of 23 ppmv as a possible
health-based emission standard for HCl would result in chronic ambient
levels of acid gases that would not pose significant health risks. EPA
has no data that would allow us to extend that analysis to cover all
acid gases and all facilities.
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    \32\ It should be noted that large amounts of site-specific
information both on kiln operation and local meteorological
information is needed to obtain meaningful results from AERSCREEN
and other dispersion models. This information is in the ready
possession of the industrial sources themselves, but for unknown
reasons, was not provided by industry to EPA either as part of the
2006 PCA analysis or in response to subsequent data solicitations by
EPA.
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    In addition to potential health impacts, EPA has evaluated the
potential for environmental impacts when considering whether to
exercise discretion under section 112(d)(4). When HCl gas encounters
water in the

atmosphere, it forms an acidic solution of HCl. In areas where the
deposition of acids derived from emissions of sulfur and nitrogen
oxides are causing aquatic and/or terrestrial acidification, with
accompanying ecological impacts, the deposition of HCl could exacerbate
these impacts. Being mindful of the explicit legislative history, and
in keeping with past EPA practice, it is appropriate to consider
potential adverse environmental effects in addition to adverse health
effects when setting an emission standard for HCl under section
112(d)(4). The co-emissions of HF, HCN, and Cl2 from cement
kilns could serve to further aggravate these environmental
acidification impacts, but EPA has no data to determine these impacts.
    Although the PCA analysis did not include an assessment of
potential environmental effects, for the 2006 final Portland cement
rule, EPA conducted its own analysis of potential effects of cement
kilns' HCl emissions to wildlife, aquatic life, and other natural
resources. The Agency concluded at the time that acute and chronic
exposures to expected HCl concentration around cement kilns are not
expected to result in adverse environmental toxicity effects. Id. at
76529. EPA accordingly declined to establish any standard for HCl.
    At this time, we now believe the ecological risk analysis performed
in 2006 is insufficient, as it was merely a literature review and not a
formal ecological assessment, and, as discussed in the previous
paragraphs, it did not cover the impacts of the other acid gases, nor
did it cover about one third of the existing cement plants. No
additional information was provided during the comment period which
addressed these various technical issues, notwithstanding EPA's
solicitation of data.
    Consequently, although EPA is declining to adopt a section
112(d)(4) risk-based standard for HCl emissions from Portland cement
facilities for the sound policy reasons discussed herein, we further
note that there remain technical issues as to the appropriateness of
such a standard even if EPA were inclined to exercise that discretion.
We also do not view ourselves as bound by the technical determinations
made in the 2006 rulemaking for the reasons just explained.
    EPA also has concluded that the facts here are distinguishable from
those in other rulemakings in which it exercised its discretionary
authority under section 112(d)(4). In the case of the Pulp and Paper
MACT (63 FR at 18765 (April 15, 1998)), the risk analysis indicated, at
the 95 percent confidence interval, that the maximum concentration
predicted to which people were estimated to be exposed was 0.3 g/
m3, 60 times less than the inhalation reference
concentration. This is a much lower value than present in the Portland
cement risk analysis discussed above. In the case of the Lime
Manufacturing NESHAP (67 FR at 78054 (Dec. 20, 2002)), there are two
key distinctions. First, the technical information available to EPA
covered 100 percent of all lime kilns in the U.S., which is not the
case for the Portland cement risk analysis. Second, EPA did a worst
case analysis as a supplement to the industry analysis and determined
that the highest hazard index under that scenario was 0.21. Based on
the EPA analysis determining a health based limit for Portland cement,
if we were to allow the same level of risk as we determined in Lime
NESHAP analysis, the health based emission limit would be 2 ppmvd,
which is almost the same level as the MACT standard we are finalizing
in this action.
    EPA also considers the alternative standard for total chlorine in
the Hazardous Waste Combustor MACT (70 FR at 59555 (Oct. 12, 2005)) to
be distinguishable. That rule, under the authority of section 112(d)(4)
establishes a site-specific risk-based standard for total chlorine (of
which HCl is the largest component), whereby, in lieu of meeting the
MACT standard, sources may emit total chlorine at higher levels if they
demonstrate that their emissions of total chlorine from all hazardous
waste combustor sources at a facility do not exceed both acute (one-
hour) and chronic (annual) exposure thresholds. The demonstration must
account for all relevant site-specific conditions, or be based on
worst-case screening assumptions. If sources satisfy these criteria,
the amount of their total chlorine emissions is still capped by the
technology-based limit to which these sources were previously subject.
The site-specific demonstrations, applicability to all combustor
sources at a facility, use of acute and chronic health benchmarks, and
capping of emission limits are all unique to that rule.
e. PM Emissions From Kilns
    Particulate matter serves as a surrogate for non-volatile metal HAP
(a determination upheld for this source category in National Lime
Ass'n, 233 F. 3d at 637-39). Existing and new major sources are
presently subject to a PM limit of 0.3 lb/ton of feed which is
equivalent to 0.5 lb/ton clinker. EPA is amending this standard for
major sources, and also adding PM standards for existing and new area
source cement kilns. In all instances, EPA is revising these limits
because they do not represent MACT, but rather a level which is
achievable by the bulk of the industry. See 63 FR at 14198 (March 24,
1998); see also 233 F. 3d at 633 (indicating that the standards for PM
were likely legally deficient but that the argument had not been