[Federal Register Volume 77, Number 138 (Wednesday, July 18, 2012)]
[Proposed Rules]
[Pages 42367-42412]
[FR Doc No: 2012-16166]

Vol. 77

Wednesday,

No. 138

July 18, 2012

Part II

Environmental Protection Agency

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40 CFR Parts 60 and 63

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

Federal Register / Vol. 77 , No. 138 / Wednesday, July 18, 2012 /
Proposed Rules

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 60 and 63

[EPA-HQ-OAR-2011-0817; FRL-9692-9]
RIN 2060-AQ93

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

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rules on reconsideration.

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SUMMARY: The EPA is proposing amendments to the National Emission
Standards for Hazardous Air Pollutants for the Portland cement industry
for Portland cement plants issued under sections 112(d) of the Clean
Air Act. Specifically, the EPA is proposing to amend the existing and
new source standards for particulate matter (PM). The EPA is also
proposing amendments with respect to issues on which it granted
reconsideration on May 17, 2011. In addition, the EPA is proposing
amendments to the new source performance standard for PM issued
pursuant to section 111(b) of the Clean Air Act. These proposed
amendments would promote flexibility, reduce costs, and ease compliance
burdens. EPA is also addressing the remand of the emission standards in
the NESHAP by the D.C. Circuit on December 9, 2011. Finally, the EPA is
proposing to extend the date for compliance with the existing source
national emission standards for hazardous air pollutants to September
9, 2015.

DATES: Comments must be received on or before August 17, 2012. Any
requests for a public hearing must be received by July 30, 2012. If the
EPA holds a public hearing, the EPA will keep the record of the hearing
open for thirty days after completion of the hearing to provide an
opportunity for submission of rebuttal and supplementary information.
Under the Paperwork Reduction Act, comments on the information
collection provisions are best assured of having full effect if the
Office of Management and Budget receives a copy of your comments on or
before August 17, 2012.

ADDRESSES: Submit your comments, identified by Docket ID Number EPA-HQ-
OAR-2011-0817, by one of the following methods:
     Federal Rulemaking Portal: http://www.regulations.gov.
Follow the online instructions for submitting comments.
     Agency Web site: http://www.epa.gov/oar/docket.html.
Follow the instructions for submitting comments on the EPA Air and
Radiation Docket Web site.
     Email<EMAIL_ADDRESS>Include EPA-HQ-OAR-2011-
0817 in the subject line of the message.
     Fax: Fax your comments to:<PHONE_NUMBER>, Attention
Docket ID Number EPA-HQ-OAR-2011-0817.
     Mail: Send your comments to: The EPA Docket Center (EPA/
DC), Environmental Protection Agency, Mailcode: 2822T, 1200
Pennsylvania Ave. NW., Washington, DC 20460, Attention: Docket ID
Number EPA-HQ-OAR-2011-0817. Please include a total of two copies. In
addition, please mail a copy of your comments on the information
collection provisions to the Office of Information and Regulatory
Affairs, Office of Management and Budget (OMB), Attn: Desk Officer for
the EPA, 725 17th Street NW., Washington, DC 20503.
     Hand Delivery or Courier: In person or by courier, deliver
comments to the EPA Docket Center, EPA West (Air Docket), Room 3334,
1301 Constitution Ave. NW., Washington, DC 20460, Attention Docket ID
Number EPA-HQ-OAR-2011-0817. Such deliveries are only accepted during
the Docket's normal hours of operation (8:30 a.m. to 4:30 p.m., Monday
through Friday, excluding legal holidays), and special arrangements
should be made for deliveries of boxed information. Please include two
copies.
    Instructions: Direct your comments to Docket ID Number EPA-HQ-OAR-
2011-0817. The EPA policy is that all comments received will be
included in the public docket without change and may be made available
online at http://www.regulations.gov, including any personal
information provided unless the comment includes information claimed to
be confidential business information (CBI) or other information whose
disclosure is restricted by statute. Do not submit information that you
consider to be CBI or otherwise protected through http://www.regulations.gov or email. The http://www.regulations.gov Web site
is an ``anonymous access'' system, which means the EPA will not know
your identity or contact information unless you provide it in the body
of your comment. If you send an email comment directly to the EPA
without going through http://www.regulations.gov, your email address
will be automatically captured and included as part of the comment that
is placed in the public docket and made available on the Internet. If
you submit an electronic comment, the EPA recommends that you include
your name and other contact information in the body of your comment and
with any disk or CD-ROM you submit. If the EPA cannot read your comment
due to technical difficulties and cannot contact you for clarification,
the EPA may not be able to consider your comment. Electronic files
should avoid the use of special characters, any form of encryption and
be free of any defects or viruses. For additional information about the
EPA public docket, visit the EPA Docket Center homepage at http://www.epa.gov/epahome/dockets.htm.
    Docket. The EPA has established a docket for this rulemaking under
Docket ID Number EPA-HQ-OAR-2011-0817. All documents in the docket are
listed in the http://www.regulations.gov index. Although listed in the
index, some information is not publicly available (e.g., CBI or other
information whose disclosure is restricted by statute). Certain other
material, such as copyrighted material, will be publicly available only
in hard copy. Publicly available docket materials are available either
electronically in http://www.regulations.gov or in hard copy at the EPA
Docket Center, EPA West, Room 3334, 1301 Constitution Ave. NW.,
Washington, DC. The Public Reading Room is open from 8:30 a.m. to 4:30
p.m., Monday through Friday, excluding legal holidays. The telephone
number for the Public Reading Room is<PHONE_NUMBER>, and the telephone
number for the EPA Docket Center is<PHONE_NUMBER>. Note that
information pertinent to the previous Portland cement rulemakings
discussed in this document is contained in dockets EPA-HQ-OAR-2002-0051
and EPA-HQ-OAR-2007-0877.
    Public Hearing. If a public hearing is held, it will begin at 10:00
a.m. on August 2, 2012 and will be held at the EPA campus in Research
Triangle Park, North Carolina, or at an alternate facility nearby.
Persons interested in presenting oral testimony or inquiring as to
whether a public hearing is to be held should contact Ms. Pamela
Garrett, Office of Air Quality Planning and Standards, Sector Policies
and Programs Division, Metals and Minerals Group (D243-01), U.S.
Environmental Protection Agency, Research Triangle Park, North Carolina
27711; email<EMAIL_ADDRESS>telephone number:<PHONE_NUMBER>.
Persons interested in presenting oral testimony or inquiring as to
whether a public hearing is to be held should contact Ms. Garrett at
least 2 days in advance of the potential date of the public hearing.

FOR FURTHER INFORMATION CONTACT: Ms. Sharon Nizich, Office of Air
Quality Planning and Standards; Sector Policies and Programs Division,
Minerals and Manufacturing Group (D243-04); Environmental Protection
Agency; Research Triangle Park, NC 27111; telephone number: (919) 541-
2825; fax number:<PHONE_NUMBER>; email address<EMAIL_ADDRESS>
SUPPLEMENTARY INFORMATION: The information presented in this preamble
is organized as follows:

I. General Information
    A. Executive Summary
    B. Does this action apply to me?
    C. What should I consider as I prepare my comments to the EPA?
    D. Where can I get a copy of this document?
II. Background Information
    A. What is the statutory authority for these proposed
amendments?
    B. What actions preceded this proposed rule?
III. Description of Proposed Amendments to Subpart LLL and Subpart F
    A. Reconsideration of Standards
    B. Mercury Standard
    C. THC Standard
    D. Proposed Amendments to Existing Source and New Source
Standards for PM Under Section 112(d) and 111(b)
    E. Summary of Proposed Standards Resulting From Reconsideration
    F. Standards for Fugitive Emissions From Clinker Storage Piles
    G. Affirmative Defense to Civil Penalties for Exceedances
Occurring During Malfunctions
    H. Continuously Monitored Parameters for Alternative Organic HAP
Standard (With THC Monitoring Parameter)
    I. Allowing Sources With Dry Caustic Scrubbers to Comply With
HCl Standard Using Performance Tests
    J. Alternative PM Limit
    K. Standards During Startup and Shutdown
    L. Coal Mills
    M. PM Standard for Modified Sources Under the NSPS
    N. Proposed NESHAP Compliance Date Extension for Existing
Sources
    O. Eligibility to be a New Source
IV. Other Proposed Testing and Monitoring Revisions
V. Other Changes and Areas Where We Are Requesting Comment
VI. Summary of Cost, Environmental, Energy and Economic Impacts of
Proposed Amendments
    A. What are the affected sources?
    B. How are the impacts for this proposal evaluated?
    C. What are the air quality impacts?
    D. What are the water quality impacts?
    E. What are the solid waste impacts?
    F. What are the secondary impacts?
    G. What are the energy impacts?
    H. What are the cost impacts?
    I. What are the health effects of these pollutants?
VII. Statutory and Executive Order Reviews
    A. Executive Order 12866: Regulatory Planning and Review and
Executive Order 13563: Improving Regulation and Regulatory Review
    B. Paperwork Reduction Act
    C. Regulatory Flexibility Act
    D. Unfunded Mandates Reform Act
    E. Executive Order 13132: Federalism
    F. Executive Order 13175: Consultation and Coordination With
Indian Tribal Governments
    G. Executive Order 13045: Protection of Children From
Environmental Health Risks and Safety Risks
    H. Executive Order 13211: Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use
    I. National Technology Transfer and Advancement Act
    J. Executive Order 12898: Federal Actions To Address
Environmental Justice in Minority Populations and Low-Income
Populations

I. General Information

A. Executive Summary

    The EPA is proposing amendments to the emissions standards for
hazardous air pollutants (HAP) and to the performance standards for
Portland cement plants. These proposed amendments respond to petitions
for reconsideration filed by the Portland cement industry and to a
decision by the United States Court of Appeals for the District of
Columbia Circuit (D.C. Circuit). These amendments, which are consistent
with the CAA, if adopted, will also provide less costly compliance
options and compliance flexibilities, and thereby result in cost
savings for the Portland cement industry. This result would also be
consistent with Executive Order 13563. The proposed amendments include
a new compliance date for the PM, mercury, HCl, and THC existing source
standards.
(1) Purpose of the Regulatory Action
    a. Need for the Regulatory Action. The EPA is proposing amendments
to the national emission standards for hazardous air pollutants
(NESHAP) for the Portland cement source category and to the new source
performance standards (NSPS) for Portland cement plants issued under
sections 112(d) and 111(b) of the Clean Air Act (CAA). Section 112 of
the CAA establishes a regulatory process to address emissions of HAP
from stationary sources. After the EPA identifies categories of sources
emitting one or more of the HAP listed in section 112(b) of the CAA,
section 112(d) requires the EPA to promulgate technology-based NESHAP
for those sources. Section 111 of the CAA requires that NSPS reflect
the application of the best system of emission reductions achievable
which, taking into consideration the cost of achieving such emission
reductions, and any non-air quality health and environmental impact and
energy requirements, the Administrator determines has been adequately
demonstrated.
    This proposal addresses the remand by the D.C. Circuit in Portland
Cement Ass'n v. EPA, 665 F. 3d 177 (D.C. Cir. 2011). In that case, the
court upheld all of the EPA's methodology for establishing the Portland
cement NESHAP, denied all petitions for review challenging the NSPS,
but also held that the EPA had arbitrarily denied reconsideration of
the NESHAP to take into account the effect of the EPA's Nonhazardous
Secondary Materials (NHSM) rule on the standards. The NHSM rule, issued
after the NESHAP was promulgated, had the effect of reclassifying some
cement kilns as commercial and industrial solid waste incinerators
(CISWI) and thus could have an effect on the standards.
    The proposal also addresses technical issues with respect to the
standard for PM in both the NESHAP and the NSPS that have emerged since
these rules' promulgation. We are proposing to amend the standard for
PM, and also proposing to amend various implementation requirements in
a way that would provide more compliance flexibilities. In addition,
the proposal addresses the issues on which the EPA previously granted
reconsideration.
    b. Legal Authority for the Regulatory Action. These proposed
amendments implement sections 112(d) and 111(b) of the CAA.
(2) Summary of Major Proposed Provisions
    a. PM (PM) Emission Standards. The EPA is proposing changes to the
emission standards for PM that potentially make available compliance
alternatives unavailable under the promulgated existing source
standards. The promulgated rule requires compliance to be demonstrated
using a Continuous Emission Monitoring System (CEMS) (see section
63.1348 (75 FR 55056)). Based on the information the EPA now has, we
believe that it may be problematic for a PM CEMS to meet the mandated
Performance Specification 11 (PS 11) correlation requirements complying
with the promulgated PM standards. (See section III.D.) As a
consequence, the EPA is proposing to amend the existing and new source
PM standards in the NESHAP to require manual stack testing in lieu of
PM CEMS for compliance determinations. An additional consequence of
this

proposed change of compliance measurement methods is that the EPA is
proposing to change the averaging time and numeric emissions value of
those standards. The EPA is proposing amended PM standards under the
NESHAP for existing sources of 0.07 pounds per ton (lb/ton) clinker
based on manual stack testing, (from 0.04 lb/ton in the 2010 rule, 30-
day average with a PM CEMS) and 0.02 lb/ton clinker for new sources
based on stack testing (from 0.01 lb/ton in the 2010 rule, 30-day
average with a PM CEMS). The EPA is proposing amended PM standards
under the NSPS for modified sources of 0.07 lb/ton clinker based on
manual stack testing, (from 0.01 lb/ton in the 2010 rule, 30-day
average with a PM CEMS) and 0.02 lb/ton clinker for new and
reconstructed sources based on stack testing (from 0.01 lb/ton in the
2010 rule, 30-day average with a PM CEMS). The EPA is further proposing
that a site-specific parametric operating limit be established, that
there be continuous monitoring of that parametric limit using a PM
CPMS, that an exceedance of that site-specific operating limit be
reported as a deviation, triggering corrective action including
conducting a Method 5 performance test within 45 days. Further,
multiple deviations from the parametric limit can constitute a
violation of the emissions standard.
    b. Response to Remand. Consistent with the court's remand, the EPA
has removed all the CISWI kilns from the database used to set the 2010
existing source standards for PM, mercury, hydrochloric acid and total
hydrocarbons (THC). The EPA then recalculated existing source floors
for each of these pollutants, and determined what standards to propose
in light of that analysis. This analysis informed the level of the
proposed standards for PM just discussed. The resulting standards are
discussed immediately below.
    c. Other Emissions Standards. The EPA is not proposing any changes
to the existing source standards for mercury, total THC or hydrogen
chloride (HCl). The reasons are set out in sections III A, B and C
below.
    With respect to new source standards, under section 112(d)(3) of
the CAA, new source floors can be based on the performance of the
``best controlled similar source.'' A CISWI cement kiln is a similar
source for purposes of this provision. The EPA, therefore, is not
proposing to amend any of the new source floors or standards for
mercury, THC or HCl where the best performing source in the database
used to set the standards was a CISWI cement kiln.
    The EPA is also proposing to amend the alternative standard for
organic HAP, whereby organic HAP are measured directly. To avoid a
situation where the alternative organic standard level is lower than
the practical quantitation limit of the relevant analytic methods, the
EPA is proposing to increase the alternative organic HAP standard from
9 parts per million (ppm) to 12 ppm. See additional discussion in
section III.H below.
    d. Standards during Startup and Shutdown. In the final 2010 NESHAP,
the EPA established specific numerical standards for startup and
shutdown for each pollutant to be measured using a CEMS over an
accumulative 7-day rolling average. Because raw materials (the source
of most cement kiln air emissions) are not introduced into cement kilns
during startup and shutdown, cement kilns' emissions during these
periods should be appreciably lower than the level of the standards.
The EPA is, therefore, proposing that sources monitor compliance with
these standards via recordkeeping.
    e. Proposed Compliance Dates. The EPA is proposing that the
compliance date for all existing source standards including standards
for PM, mercury, HCl and THC, clinker piles and the standards for
startup and shutdown be extended to September 9, 2015. The EPA believes
that the proposed change to the PM standard makes possible compliance
alternatives unavailable under the promulgated existing source
standards) and that an extension until September 9, 2015, is the period
in which these new compliance strategies can be implemented most
expeditiously.
    f. The EPA is also taking action on the remaining issues on which
it granted reconsideration on May 17, 2011.
(3) Costs and Benefits
    The following table 1 summarizes the costs and emissions reductions
of this proposed action.

  Table 1--Costs and Emissions Reductions of Proposed Amendments Relative to the 2010 Rule \a\ \b\ \c\ \d\ \e\
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             Proposed amendment                 Capital cost     Annualized cost       Emissions  reduction
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Revised PM standard.........................      -$18,640,106       -$4,200,000  -135 tons/yr (emissions
                                                                                increase).
Replace PM CEMS with PM CPMS................                 0        -7,980,000  0
                                             -------------------------------------------------------------------
    Total...................................       -18,640,106       -12,180,000
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\a\ See section III below for further discussion of impacts of the proposed amendments.
\b\ Negative numbers indicate cost savings or emissions increase. All costs are in 2005 dollars.
\c\ We also estimate that there will be a one-time cost of $25,000 for each facility to develop the calculation
  that will allow them to demonstrate compliance during periods of startup and shutdown.
\d\ Emissions reductions are the total relative to the 2010 rule once full compliance is achieved in 2015.
\e\ Full compliance costs will not occur until September 9, 2015.

    The cost information in Table 1 is in 2005 dollars at a discount
rate of 7 percent. The net change in annualized costs in 2015 is a
$12.2 million savings compared to the 2010 rule. The EPA did not have
sufficient information to quantify the overall change in benefits or
costs for 2013 to 2015 that might arise due to the proposed change in
compliance dates.
4. Summary of Proposed Standards
    The following Table 2 shows the proposed standards.

           Table 2--Proposed Existing and New Source Standards
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                                 Existing source
          Pollutant                 standard         New source standard
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Mercury.....................  55 lb/MM tons         21 lb/MM tons
                               clinker.              clinker.
THC.........................  24 ppmvd............  24 ppmvd.

PM..........................  0.07 lb/ton clinker   0.02 lb/ton clinker
                               (3-run test           (3-run test
                               average).             average).
HCl.........................  3 ppmvd.............  3 ppmvd.
Organic HAP (alternative to   12 ppmvd............  12 ppmvd.
 Total Hydrocarbon).
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B. Does this action apply to me?

    Categories and entities potentially regulated by this final rule
include:

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                                    NAICS Code    Examples of regulated
             Category                  \1\              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.

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

Submitting CBI
    Do not submit information containing CBI to the EPA through http://www.regulations.gov or email. Clearly mark the part or all of the
information that you claim to be CBI. For CBI information on a disk or
CD-ROM that you mail to the EPA, mark the outside of the disk or CD-ROM
as CBI and then identify electronically within the disk or CD-ROM the
specific information that is claimed as CBI. In addition to one
complete version of the comment that includes information claimed as
CBI, a copy of the comment that does not contain the information
claimed as CBI must be submitted for inclusion in the public docket. If
you submit a CD-ROM or disk that does not contain CBI, mark the outside
of the disk or CD-ROM clearly that it does not contain CBI. Information
not marked as CBI will be included in the public docket and the EPA's
electronic public docket without prior notice. Information marked as
CBI will not be disclosed except in accordance with procedures set
forth in 40 CFR part 2. Send or deliver information identified as CBI
only to the following address: Roberto Morales, OAQPS Document Control
Officer (C404-02), Office of Air Quality Planning and Standards, U.S.
Environmental Protection Agency, Research Triangle Park, North Carolina
27711, Attention Docket ID Number EPA-HQ-OAR-2011-0817.

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

    In addition to being available in the docket, an electronic copy of
this proposal will also be available on the World Wide Web (WWW)
through the EPA's Technology Transfer Network (TTN). Following
signature by the EPA Administrator, a copy of this proposed action will
be posted on the TTN's policy and guidance page for newly proposed or
promulgated rules at the following address: http://www.epa.gov/ttn/oarpg. The TTN provides information and technology exchange in various
areas of air pollution control.

II. Background Information

A. What is the statutory authority for these proposed amendments?

    Section 112 of the CAA establishes a regulatory process to address
emissions of HAP from stationary sources. After the 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. See CAA section
112(d)(2).\1\
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    \1\ Section 112(d)(7) states that ``[n]o other emission standard
* * * under this section shall be interpreted, construed or applied
to diminish or replace the requirements of a more stringent emission
limitation or other applicable requirement established pursuant to
section 7411 of this title, part C or D of this subchapter, or other
authority of this chapter or a standard issued under State
authority.'' This provision indicates that a section 112(d) standard
does not ``trump'' any standard established under other authority
which is more stringent. Section 112(d)(7) does not bar the EPA from
amending section 112(d) standards to correct technical deficiencies.
---------------------------------------------------------------------------

    Section 111(b) requires the EPA to set standards for emissions that
``reflect the

degree of emission limitation achievable through the application of the
best system of emission reduction.'' See CAA section 111(a)(1). In
contrast to the NESHAP floor setting process, NSPS requires the EPA to
take into account the ``cost of achieving'' emissions reductions, as
well as health, environmental, and energy considerations. Id.

B. What actions preceded this proposed rule?

    The history of this proposed rule, commencing with the 1999
standards and proceeding through the amendments issued in September
2009, is set out in detail in 75 FR 54970 (Sept 9, 2010). Various
parties filed petitions for reconsideration of aspects of those
amendments. On May 17, 2011, the EPA granted reconsideration of various
issues, and denied the petitions to reconsider as to the remaining
issues. See 76 FR 28318 (May 17, 2011). On December 9, 2011, the D.C.
Circuit issued an opinion upholding the NESHAP itself (as well as the
section 111 NSPS), but found that the EPA had arbitrarily failed to
grant reconsideration to consider the effect of the EPA's NHSM rule on
the standards (76 FR 15456 (March 21, 2011)), which rule had the effect
of reclassifying some cement kilns as commercial and solid waste
incinerators. See Portland Cement Ass'n v. EPA, 665 F. 3d 177, 186-189
(D.C. Cir. 2011). That court did not stay the standards for PM,
mercury, HCl or THC, but did stay the standard for clinker piles
pending the conclusion of the reconsideration process. See 665 F. 3d at
194.
    In this action, the EPA is responding to the court's remand. For
existing sources, the EPA is doing so by removing all kilns classified
as commercial and industrial solid waste incinerators from the data
used to establish the 2010 NESHAP standards. The EPA is then
recalculating each of the floors based on this revised dataset and
making beyond-the-floor determinations based on the recalculated
floors. The EPA believes that this approach is fully responsive to the
court's remand. See 665 F. 3d at 188 where the court referred favorably
to this type of recalculation. For new sources, the EPA is basing
floors on the performance of the best performing similar source.

III. Description of Proposed Amendments to Subpart LLL and Subpart F

A. Reconsideration of Standards

    As just noted, in Portland Cement Association v. EPA, the D.C.
Circuit upheld all of the EPA's methodology for establishing the
Portland cement NESHAP, but remanded the standards so that the EPA
could account for the effects of the EPA's NHSM rule. This rule,
adopted after promulgation of the Portland cement NESHAP, had the
effect of reclassifying certain cement kilns as commercial and
industrial incinerators because they combust ``solid waste'' as defined
by that rule. See 665 F. 3d at 185-189.
    Applying that definition, the EPA has determined that there are 24
cement kilns which combust solid waste. See 76 FR 28322 and Memorandum
``Combustion in a Cement Kiln and Cement Kilns' Use of Tires as Fuel''
(April 25, 2011) (``April 25 memorandum''); see also 76 FR 80452 (Dec.
23, 2011) where the EPA identified 23 of the 24 kilns as commercial
incinerators as were identified in the April 25 memorandum. The 24th
kiln was identified as a CISWI kiln after development of the April 25,
2011, memorandum, but the addition of this kiln did not affect the
calculations contained in the May 17, 2011 notice (CISWI Data Revisions
since Reconsideration Proposal, docket EPA-HQ-OAR-2003-0119). Although
the EPA has proposed to reconsider certain narrow aspects of the NHSM
rule, see 76 FR 80598 (Dec. 23, 2011), this count remains unchanged by
any of the issues being considered in the reconsideration of the NHSM
rule. This is because either the types of secondary materials being
addressed in that reconsideration are not combusted by cement kilns or
the EPA has already accounted for those materials in its April 25
memorandum analysis. See 76 FR 28319 (May 17, 2011). Specifically, in
the NHSM reconsideration proposal, the EPA proposed to clarify that
clean cellulosic biomass and clean construction and demolition wood are
not solid wastes when burned for energy recovery and that unused, off-
specification tires are not wastes when burned for energy recovery. The
EPA's analysis underlying its April 25, 2011, memorandum already
reflects that these non-hazardous secondary materials are not wastes
when burned by cement kilns for energy recovery. The EPA expects the
reconsideration of the NHSM rule to be completed before taking final
action on this proposed rule and the EPA will account for any changes
resulting from the reconsidered final NHSM rule when it takes final
action here.\2\
---------------------------------------------------------------------------

    \2\ The EPA has also conducted a bounding analysis of potential
floors by removing from the data base all cement kilns that burn any
type of secondary material for energy recovery (so that there is no
possibility that any CISWI kiln is in the bounding analysis
database). Under this analysis, the existing source section 112
floor for HCl was unchanged, the existing source floor for PM was
essentially unchanged, the existing source floor for THC becomes
more stringent (as in the April 25, 2011, analysis), and the
existing source mercury floor increases from 55 lb/MM ton clinker to
66 lb/MM ton clinker. However, even in this case, a beyond-the-floor
mercury limit of 55 lb/MM tons clinker would be cost effective and
the EPA would propose the same standards as under this proposal if
this bounding analysis were used in place of the analysis described
in the text. The EPA, thus, does not believe that the precise count
of CISWI kilns will affect the outcome of this rulemaking. See
Bounding Analysis for Portland Cement MACT Floors, May 14, 2012.
---------------------------------------------------------------------------

    1. Existing Source Floors. We removed the 24 CISWI kilns from the
database used to establish existing source standards and recalculated
floors for existing sources. Under this analysis, the existing source
floor for mercury increased from 55 lb/million (MM) tons clinker to 58
lb/MM tons clinker, the existing source floor for PM increased from
0.04 lb/ton clinker to 0.05 lb/ton clinker, the existing source floor
for THC decreased to 15 parts per million by volume, dry (ppmvd), and
the existing source floor for HCl stayed the same at 3 ppmvd.
    As explained in section B below, the EPA is proposing to establish
a beyond the floor standard for mercury of 55 lb/MM tons clinker.
Moreover, for reasons independent of this analysis, the EPA is
proposing to amend the existing and new source NESHAP for PM. See
section D below. The EPA is not proposing to amend the HCl standard or
the THC standard.
    2. New Source Standards. With respect to new source standards, the
EPA does not believe that any reclassification and reanalysis is
necessary under the court's opinion. New source floors can be based on
the performance of ``the best controlled similar source'', as opposed
to existing source floors which must reflect performance of sources
``in the category or subcategory''. See CAA section 112(d)(3) and
(d)(3)(A). A CISWI cement kiln is similar to a non-CISWI cement kiln
since the device is a cement kiln. Equally important, burning secondary
materials for energy recovery does not significantly alter a cement
kiln's HAP emission profile. See 76 FR 28320 (May 17, 2011)
(documenting both the basis for this conclusion and the cement
industry's agreement with it).\3\ \4\
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    \3\ The EPA is thus not reopening the new source standards (with
the exception of the PM standard, which the EPA is proposing to
amend). We will take comment on whether CISWI cement kilns can be
considered a ``similar source'' under section 112(d)(3) and whether
retention of the 2010 new source standards on this basis is
consistent with the D.C. Circuit's opinion. The EPA will not
consider comments challenging the data and methodology for the new
source standards since these are unchanged from the 2010 rule and
the EPA is not reexamining any of these issues.
    \4\ If the EPA were to reconsider the new source standards by
removing the 24 CISWI kilns from the database, then the mercury new
source floor increased from 21 to 24 lb/MM tons clinker, the THC new
source floor decreased from 24 to 11 parts per million by volume dry
(ppmvd), and the PM and HCl new source floor stayed the same at 0.01
lb/ton clinker and 3 ppmvd, respectively (see Memorandum, Revised
Portland Cement NESHAP with CISWI kilns removed, March 21, 2011).
However, as explained in the text, because CISWI cement kilns are
``similar sources'' for purposes of establishing NESHAP new source
standards, the EPA is not relying on this analysis here.

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

B. Mercury Standard

    1. New Source Standard. As explained above, the new source standard
is based on the performance of the best performing similar source.
    2. Existing Source Standard. As noted above, the recalculated
existing source floor is 58 lb/MM tons clinker produced. The EPA is
proposing a beyond-the-floor standard of 55 lb/MM ton clinker produced,
the level of the 2010 final standard. As described below, the only
difference in cost between the two levels is the incremental cost of
removing slightly more mercury, which is estimated at $2,000/lb of
mercury removed. This is because the control equipment needed for
mercury would not alter, would not need to be sized differently, and
would need to perform on average nearly identically at either a 55 lb/
MM tons clinker or a 58 lb/MM tons clinker level. That is, in planning
compliance, kilns would calibrate to achieve an average performance of
34.1 lb/MM tons clinker for a standard of 58 lb/MM tons clinker, and
31.7 for a standard of 55 lb/MM tons clinker, which translates to an
additional reduction of 2.4 lb/MM tons of clinker per year. This
equates to an estimated 180 pounds of nationwide mercury emissions per
year, incremental to the recalculated floor. To achieve this additional
reduction, we estimated an additional cost of approximately $355,000
for the industry, the cost of purchasing additional carbon injection
materials. This equates to a cost-effectiveness of $2,000/lb of mercury
reduction per year. This is the incremental cost of going from the
recalculated floor of 58 lb/MM tons clinker to the proposed 55 lb/MM
tons clinker. Because this is the same level as the 2010 rule, there
are no incremental costs or emissions impacts when compared to the 2010
rule. See section 8.2, Portland Cement Reconsideration Technical
Support Document. Moreover, this reduction is highly cost-effective. A
cost effectiveness value of $2,000/lb. mercury is considerably less
than values the EPA have found to be cost effective for removal of
mercury in other air toxics rules. For example, in the National
Emission Standards for Hazardous Air Pollutants: Mercury Emissions from
Mercury Cell Chlor-Alkali Plants, the cost effectiveness was found to
be between $13,000 to $31,000 per pound for the individual facilities
(see Supplemental proposed rule, 76 FR 13858 (March 14, 2011)). The EPA
also does not see any adverse energy or non-air quality health or
environmental consequences of a 55 lb/MM tons clinker beyond-the-floor
standard.
    We are not proposing a beyond the floor level below 55 lb/MM tons
clinker for the same reasons given in the 2010 final rule--in
particular the possibility that a lower standard could force some kilns
to find alternative sources of limestone, at enormous cost and
disruption. See 75 FR 54980 (September 9, 2010).

C. THC Standard

    The THC data for the 2010 standard consist of CEMS data for 15
kilns. After removing the four CISWI kilns, nine kilns remain. Thus,
the MACT floor kilns consisted of 12 percent of these nine kilns, or
two kilns. The top two kilns were Suwannee and Holcim. As explained
above, when CISWI sources are removed from the database for the 2010
standards, the existing source floor for THC becomes more stringent
from 24 ppmvd to 15 ppmvd, and the new source standard would drop from
24 ppmvd to 11 ppmvd. This change results from removing from the
database a CISWI cement kiln (the Lehigh Union Bridge kiln) with the
lowest daily average performance but with more associated variability
than the other kilns with the next highest daily average performance.
See also 76 FR 28322 (May 17, 2011) n. 11 and 665 F. 3d at 188.
However, notwithstanding this calculation, the EPA is not proposing to
reduce the level of either the new source or the existing source THC
standard.
    1. New Source Standard. As just explained, the new source standard
can be based on performance of a ``best controlled similar source'', so
there is no reason under the statute or the court's remand to amend the
new source THC standard. The standard is also technically appropriate.
See 75 FR 54981 (September 9, 2010) (explaining basis for the THC new
source standard, which discussion is summarized below for the readers'
convenience). Removing the CISWI Union Bridge kiln as the best
performing new source would leave the Suwannee kiln as the lowest
emitter based on its daily average THC emissions. See Portland Cement
Reconsideration Technical Support Document (TSD), section 8.4, which is
available in this rulemaking docket. This kiln has higher average
emissions than the Union Bridge kiln (that is, its daily average
emissions are higher than the Union Bridge kiln). This kiln thus emits
more THC than the Union Bridge kiln, so the EPA identified the kiln
emitting less THC on average--the Union Bridge kiln--to be the best
performer. The Suwannee kiln has less measured variability than the
Union Bridge kiln, but also has hundreds of fewer observations. For
this reason, the EPA considered the Union Bridge kiln to be more
representative of variability, and used its 99th percentile performance
as the measure of performance of the best performing similar source in
establishing the new source standard. See 75 FR 54981 (September 9,
2010).\5\
---------------------------------------------------------------------------

    \5\ For purposes of comparing the relative variability of the
THC CEMS data for each of the kilns in our THC data set, we used the
ratio of the 99th percentile for each kiln divided by its daily
average. A ratio of 1.0 indicates no variability. As the ratio
increases, variability increases. See Portland Cement
Reconsideration TSD, section 8.4, which is available in this
rulemaking docket.
---------------------------------------------------------------------------

    2. Under the calculation described above, the existing source floor
would be reduced from 24 ppmvd to 15 ppmvd. Subject to any comments the
EPA receives on this proposed action, the EPA believes that such a
floor level would not be technically appropriate. It omits the
variability of the similar source with the best average performance for
THC (the Union Bridge kiln), and so may not be fully representative of
variability of best performing sources. As noted above, cement kiln HAP
emissions are not appreciably affected by burning secondary materials
for energy recovery so the Union Bridge's variability is representative
of cement kiln variability. In addition, as noted above, the number of
daily observations for the Union Bridge kiln is among the most robust
in the database, containing over 3 times the number of observations as
the next best performing cement kiln. Thus, there is a ``demonstrated
relationship'' between the variability of the Union Bridge kiln and the
variability of the best performing sources in the existing source floor
pool. Sierra Club v. EPA, 479 F. 3d 875, 882 (D.C. Cir. 2007). The EPA
consequently believes it is technically justified to consider the

Union Bridge kiln's variability in estimating the variability of the
best performing cement kilns for THC emissions.
    If the variability of the Union Bridge kiln is included along with
the variability of the two best performing cement kilns, and applied to
the two best performing cement kilns' performance, the floor would be
24 ppm, which the EPA is proposing as a floor. See Portland Cement
Reconsideration TSD, section 8.4. This is the level of the 2010
standard.
    3. Beyond the floor standards. The EPA is not proposing a beyond
the floor THC standard for existing cement kiln sources. The reasons
given in the rulemaking remain valid. See 75 54983 (September 9, 2010);
74 FR 21153 (May 6, 2009). We especially note that a more stringent
standard for THC would force the increased use of energy-intense
control technologies like regenerative thermal oxidizers (RTO) which
have negative environmental implications, notably increased emission of
carbon dioxide (CO2) and other greenhouse gases, as well as
increased emissions of nitrogen oxide (NOX), carbon
monoxide, sulfur dioxide (SO2) and PM10. See 74
FR 21153 (May 6, 2009).\6\ These devices are also extremely costly and
not cost-effective. See 74 FR 21153 (May 6, 2009). For a description of
the costs, energy requirements and environmental impacts of RTO, see
Summary of Environmental and Cost Impacts for Final Portland Cement
NESHAP and NSPS, August 6, 2010, docket no. EPA-HQ-OAR-2002-0051-3438.
For all these reasons, the EPA does not consider a beyond-the-floor
standard for THC to be justified under section 112(d)(2). Consequently,
the EPA is not proposing a beyond-the-floor standard for THC for
existing sources.\7\
---------------------------------------------------------------------------

    \6\ The EPA estimates that each thermal oxidizer emits an added
increment of 0.02 tons of CO2 for each ton of clinker
produced. A typical kiln producing 1.2 million tons of clinker per
year and controlled by an RTO would emit an additional 24,000 tons
of CO2 per year. See RTO Secondary Impacts, May 16, 2012,
in this rulemaking docket.
    \7\ The EPA is also proposing to amend the alternative standard
for organic HAP under which organic HAP is measured directly. See
section I below.
---------------------------------------------------------------------------

D. Proposed Amendments to Existing Source and New Source Standards for
PM Under Section 112(d) and 111(b)

    Based largely on developments which have occurred after the EPA
granted reconsideration on certain aspects of the NESHAP \8\, the EPA
is proposing revisions to the testing and monitoring methods used to
demonstrate continuous compliance with the existing and new source PM
emissions standards and is proposing changes to the averaging time,
level, and compliance demonstration for those standards. The EPA has
also removed all CISWI kilns from the data base used to establish the
standards for PM and used this revised data base in determining the
level of the standard, consistent with the court's remand. We explain
these proposed changes below.
---------------------------------------------------------------------------

    \8\ On November 15, 2011, Holcim (US) Inc., a domestic cement
company, submitted a petition for reconsideration to the EPA
requesting that the EPA reconsider and stay the NESHAP PM standard.
The basis for the petition was CEMS data for PM from four of
Holcim's kilns (some of which are either waste-burning or hazardous
waste burning). Petition pp. 5-6. This information was collected
commencing in January 2011. Since the information in the petition
was gathered outside the time period mandated by section
307(d)(7)(B) of the Act--even assuming it was impractical to raise
the objection during the public comment period, the grounds arose
outside the time period for judicial review which ended in November
2010. Thus, the EPA believes that it is not compelled to grant this
petition. Moreover, as discussed in the text below, because the EPA
is proposing to no longer use a CEMS-based regime for the PM
standard, the Holcim information is no longer of direct relevance in
setting the level of the PM standard. A further issue with the data
is that they were not obtained using CEMS calibrated according to
PS-11, the protocol specified in the rule. Accordingly, the EPA is
not basing its proposal of a revised PM standard on these data. The
EPA is not, however, taking final action on the Holcim petition at
this time, but intends to do so in conjunction with the issuance of
the final reconsideration rule.
     On January 17 2012, LaFarge Cement submitted a petition for
reconsideration containing no new data or information but arguing
that the Holcim petition justified reconsideration of the standards.
The EPA believes that this petition is subsumed by the Holcim
petition.
---------------------------------------------------------------------------

    In comments to the 2009 proposal, industry commenters maintained
that there were several problems with implementing the monitoring
requirements to demonstrate compliance using a PM CEMS and with the
requirements to conduct a periodic audit of the PM CEMS in accordance
with Performance Specification (PS) 11 of appendix B and Procedure 2 of
appendix F to part 60. The EPA responded to these comments in the 2010
final rule. See 75 FR 55007 (September 9, 2010); NESHAP Response to
Comment Document pp. 163-166. Since that time, the Portland cement
industry has identified further technical issues associated with the
current PM CEMS technology in satisfying PS 11 correlation requirements
that have emerged as the industry has attempted to develop a CEMS-based
compliance strategy for PM pursuant to the 2010 NESHAP.
    1. PS 11. The EPA has continued to review the application of PM
CEMS in relation to the procedures and acceptance criteria of PS 11,
the protocol mandated by the promulgated rule. See section
63.1350(b)(1). PS 11 is structured differently than other PS that apply
to validating the performance of gaseous pollutant CEMS. This is
primarily because the pollutant, PM, is defined entirely by the test
method specified by regulation to measure it. As the industry
commenters note, there are no independent standard reference materials
for PM concentrations as there are for gaseous pollutants (e.g., NIST
traceable compressed gases for validating SO2 or
NOX instrumental measurements). The only reference standard
for determining the PM concentration in an air or stack gas sample is
the reference test method. In the case of the Portland cement NESHAP
(and NSPS), the rule specifies the EPA Method 5 for measuring
filterable PM concentration or mass rate (e.g., in mg/dscm or lb/hr).
    PS 11 provides procedures and acceptance criteria for validating
the performance of several types of PM CEMS technologies. Although
there are multiple instrument and data reporting operational
performance checks in PS 11 that are similar in concept to those for
gaseous pollutant CEMS, there is the principal PM CEMS performance
requirement that is distinctly different. That requirement is the
development of a site-specific PM CEMS correlation or mathematical
response curve. There is a key procedural element to developing that
correlation. That is, PS 11 requires that the source conduct multiple
stack test runs using an EPA PM test method (e.g., Method 5) and
simultaneously collect corresponding PM CEMS output data. PS 11,
section 8.6, requires at least five test runs at each of three
different operating (i.e., low, mid, and high PM concentration)
conditions that range from 25 to 100 percent of allowable emissions, if
possible, for a total of 15 or more test runs. Then the source must use
the test method data and the corresponding PM CEMS output data to
develop an equation (i.e., a calculated linear or nonlinear curve) that
will be used to define the relationship between the PM CEMS output and
the test method measured PM concentrations. Each site-specific
correlation must meet several PS 11 acceptance criteria including
limits on confidence interval and tolerance interval equating to 25 percent of the applicable emissions limit.
    2. Discussion of Technical Issues. A particular challenge in
applying PM CEMS to source emissions monitoring is in measuring the
very low PM concentrations associated with a low applicable emissions
limits for PM precisely enough to meet the PS 11 correlation
requirements. In addition to

measurement uncertainty inherent in PM CEMS data, the measurement
uncertainty associated with the reference test method (e.g., Method 5)
is a significant contributor to successful development of a PM CEMS
correlation regardless of the type of PM CEMS used.
    As noted above, PS 11 specifies acceptable criteria for a
correlation directly related to the applicable emissions limit. The
Portland cement NESHAP PM emissions limit for existing sources of 0.04
lb/ton of clinker equates to 5 to 8 mg/dscm, depending on production
rate (assuming a typical total gas flow rate per clinker production
rate). For a PM CEMS set up to measure compliance with a 5 to 8 mg/dscm
equivalent limit, the inherent uncertainty associated with a 1 hour
Method 5 measurement (0.6 to 1.2 mg/dscm) would constitute
more than half of the 25 percent of the applicable PS 11
acceptance threshold (i.e., 1.2 to 2.0 mg/dscm) of the mid-
level PS 11 correlation test (i.e. the correlation for the middle of
the three PS 11 correlation points).
    Although one can improve the method detection capabilities of the
Method 5 or other filterable PM test method by increasing sampling
volume and run time, uncertainties in measurement would remain. For
example to achieve a practical quantitation limit of 1 mg/dscm, one
would need to conduct a test run of 6 hours or longer. The measurement
uncertainty associated with a 6-hour Method 5 test runs at this
concentration would be 0.01 to 0.2 mg/dscm. At this level,
the uncertainty associated with the PM test method measurements alone
would be about half of the correlation limit allowed in PS 11. The PS
11 correlation calculations would also have to account for any PM CEMS
measurement uncertainty.
    Factoring in the inherent PM CEMS response variability and the
uncertainty associated with the representative sampling (e.g., PM and
flow stratification), we agree with commenters that trying to satisfy
PS 11 at such low concentrations using 1 hour Method 5 test runs could
be problematic. The same issue arises for the new source standard
because of the lower limit of the new source standard.
    The industry also argued that the variable raw feed material and
chemical additives used in cement production will lead to changes in
particle size, refractive index, particle density, and other physical
characteristics of the particulate in the exhaust stream. This is
important, according to the comments, because correlations developed
for the light scatter and scintillation PM CEMS technology may be
adversely affected by these physical changes in particles irrespective
of changes in mass emissions rates or concentrations.
    In developing the 2010 final rule, the EPA assumed that cement
kilns would be using light-scatter or scintillation PM CEMS.\9\ The
output or response of these light based detectors is a function of the
index of refraction or photoelectric effects and the size distribution
of the particles in the exhaust stream. In addition to being more
sensitive than opacity monitors, light based detectors provide several
degrees of design freedom not applicable to opacity monitors. PM CEMS
manufacturers account for characteristics such as light wavelength,
scattering angle, and solid angle of detection in designing instruments
with desired response features. These types of PM CEMS can be reliably
calibrated per PS 11 where the relative characteristics (e.g.,
distribution of size, shape, and constituents) of the PM in the exhaust
remain relatively constant. Such may be the case, for example, where
the PM being measured is predominantly combustion ash from burning
fossil fuels in a boiler or an electricity generating unit.
---------------------------------------------------------------------------

    \9\ US EPA, CEMS Cost Model, July 2006.
---------------------------------------------------------------------------

    The dominant sources of PM from a cement kiln are not from fuel
combustion but from processing raw materials. Cement kilns process
mostly limestone with naturally occurring variability in component
percentages. See 74 FR 21142 (May 6, 2009); 75 FR 54977 (September 9,
2010). Cement kiln operators also add other chemical additives in
variable concentrations to produce certain product characteristics. See
74 FR 21142. As noted in the EPA's technology background documents
(e.g., http://www.epa.gov/ttn/emc/cem/pmcemsknowfinalrep.pdf and http://www.epa.gov/ttn/emc/cem/r4703-02-07.pdf), the correlations developed
for light-scatter or scintillation PM CEMS devices may be adversely
affected when there are changes in the particle structure, size, and
other physical characteristics of the emissions. These changes in
emissions characteristics can occur with the variability inherent in
the composition of fuels and raw feed materials, with use of mixed
multiple fuels, or with addition of chemical additives in various
proportions.\10\
---------------------------------------------------------------------------

    \10\ Memorandum, from C. Oldham to B. Schell, Particulate Matter
Continuous Emission Monitoring System (PM CEMS) Capabilities, June
13, 2012.
---------------------------------------------------------------------------

    This is an issue of special import for cement kilns. One can expect
significant variations in particle size distribution and other particle
characteristics in Portland cement kiln exhaust because of the
complicating effects of variable content feed materials and chemical
additives. That means that correlations developed for one set of
conditions may not apply with changes in feed materials or under other
operating conditions (e.g., different chemical additives).
    The EPA has investigated whether PM CEMS that work on principles
other than light scattering could effectively measure cement kiln PM
and be calibrated per PS 11 requirements. There is at least one other
PM CEMS technology, beta attenuation PM CEMS, also referred to as beta
gauge technology that is much less sensitive to changes in particle
characteristics than are light based detectors. The beta attenuation PM
CEMS extracts a sample for the stack gas and collects the PM on a
filter tape. The device periodically advances the tape from the
sampling mode to an area where the sample is exposed to Beta radiation.
The detector measures the amount of beta radiation emitted by the
sample and that amount can be directly related to the mass of PM on the
filter.
    The majority of PM CEMS devices used to date by cement kilns are
based on light scatter or scintillation detection. We understand that a
few Portland cement operators have applied beta attenuation devices.
Since the EPA premised the rule on use of a different type of PM CEMS,
since there is minimal operating experience with beta gauge PM CEMS in
this industry, and because we are not aware that the experience
includes a beta gauge PM CEMS calibrated per PS 11, the EPA believes
that some type of research effort involving testing would be needed
before predicating a PM standard on use of a beta gauge PM CEMS. Such
an effort is likely to take several years to implement.\11\
---------------------------------------------------------------------------

    \11\ We also note that PS 11 provides for means to minimize the
effects of changing particle sizes, for example by developing
multiple correlation curves, each of which requires 15 Method 5 test
runs. The EPA did not consider such an approach in promulgating the
rule and again, further technical work is needed to ascertain if
such an approach would yield reliable results.
---------------------------------------------------------------------------

    These issues exacerbate the uncertainties of calibrating PM CEMS at
the level of the 2010 p.m. standards noted above. Using data from
longer Method 5 test runs will improve the probability of a PM CEMS
meeting PS 11 correlation requirements but will also raise practicality
concerns potentially without completely resolving the problems. Given
the combination of the low emissions concentrations PM CEMS measurement

uncertainty factors discussed above, the variability in composition of
cement PM, and need for extraordinarily long test runs to reduce Method
5 uncertainty to a level that compensates sufficiently for the PM CEMS
measurement uncertainty, the EPA believes that this correlation will
not be technically or practically achievable for a significant number
of cement kiln sources.
    3. A monitoring approach alternative to PM CEMS and PS 11. To
address technical issues associated with PM CEMS meeting PS 11
correlation requirements at low PM emissions concentrations from cement
kilns and the potentially variable PM emissions characteristics
expected from Portland cement kilns, the EPA is proposing to change the
compliance basis for the PM emissions limit from PM CEMS and the 30-day
average emissions calculation. For monitoring continuous compliance,
the rule would require PM CEMS equipment but, as explained below, that
equipment would be used for continuous parametric monitoring rather
than for direct measure of compliance with the numerical PM emissions
limit.
    The EPA is proposing to change the means of demonstrating
compliance from PM CEMS to Method 5 stack testing. In applying Method
5, PM is withdrawn isokinetically from the source and collected on a
glass fiber filter maintained at a temperature of 120  14
[deg]C (248  25[deg]F). The PM mass, which includes any
material that condenses at or above the filtration temperature, is
determined gravimetrically after the removal of uncombined water.
Compliance with the numerical emissions limit is then based on an
average of three 2-hour test runs rather than a 30-day average
determined from PM CEMS data. The numerical level of the standard would
change to reflect the different averaging period. See 75 FR 54988
(September 9, 2010) (explaining that more measurements of a properly
designed and operated control device decreases measured variability
since there are likely to be more measurements at the mean of
performance); see also 75 FR 54975 (September 9, 2010) (explaining how
this phenomenon is reflected in the Upper Prediction Limit (UPL)
equation used to project variability, since the m term (i.e., the
number of measurements) in the equation becomes larger with more
observations resulting in a larger denominator and hence lower ultimate
level). By changing from a 30-day average with potentially 720 hourly
values to a three-run test average producing three test run values, we
reviewed and revised the calculation of the PM emissions floor and
standard, and consistent with the court's remand, removed all CISWI
kilns from the database in doing so. In calculating the PM MACT floor,
the best performing kilns used in the analysis changed as a result of
removing the kilns identified as CISWI kilns.
    In addition, we realized that in the original analysis PM emissions
data for a single kiln were inadvertently treated as test results for
three different kilns. After making that correction and after
eliminating kilns identified as CISWI, the number of kilns in the data
set was reduced from 45 kilns to 28 kilns. Therefore, the best
performing 12 percent was represented by four kilns. As a result of
removing the CISWI kilns, two kilns which were not best performers in
the 2010 dataset are now best performers. See TSD section 8.3 and
Appendices E and F.
    As in the 2009 proposal, we used individual test run data from our
best performing kilns and calculated the 99th confidence UPL. Rather
than using m = 30 in the equation as we did in the 2010 final rule
where compliance was based on a 30 day rolling average, see 75 FR 54988
(September 9, 2010), we used m = 3 consistent with the proposed
requirement to determine compliance using a three run Method 5 test.
Under this analysis, we determined the revised proposed PM MACT floor
to be 0.07 lb/ton clinker produced when based on the three run Method 5
test. Beyond-the-floor standards do not appear to be justified for the
same reasons given in the 2010 final rule. See 75 FR 54988 (September
9, 2010). We are, therefore, proposing this emissions limit for the
kiln and clinker cooler and an initial and annual compliance test using
Method 5 to demonstrate compliance.
    These issues affecting the existing source PM limit also apply to
the new source PM limit. Based on this revised compliance regime, the
new source floor would change from 0.01 lb/ton clinker produced, to
0.02 lb/ton clinker produced, based on a three run average from a
Method 5 stack test. See Portland Cement Reconsideration TSD, section
8.3. The best performing kiln used to set the MACT floor for new
sources in the 2010 rule was a cement kiln, not a CISWI kiln, so the
same kiln was used for this analysis. The difference is that because a
3-run test would be used to determine compliance rather than a 30-day
rolling average, the calculation of the 99th confidence UPL used m = 3
rather than 30, which results in a floor of 0.02 lb/ton clinker. The
EPA is not proposing a beyond-the-floor standard for the reasons given
at 75 FR 54988 (September 9, 2010).
    As indicated above, the EPA is further proposing to use PM CEMS
technology for continuous parametric monitoring of the proposed PM
standards. The EPA has developed requirements for continuously
monitoring operating parameters in instances where compliance is based
on non-continuous measurements, as would now be the case for PM. This
implements section 114(a)(3) of the CAA which requires major sources to
use enhanced monitoring for compliance certifications. The EPA's
historic approach has been to require monitoring of a control device
operating condition (e.g., electrical power, water flow rate, pH) the
limit of which is based on a periodic compliance test with the
compliance test method. The use of a continuous parametric monitoring
system (CPMS) based on PM CEMS technology (PM CPMS) is a significant
step closer to direct measurement of emissions in units of the
emissions limit and an improvement over less direct monitoring of a
process control device conditions.
    Specifically, this proposal recognizes the value of PM monitoring
technology sensitive to changes in PM emissions concentrations and use
of such a tool to assure continued good operation of PM control
equipment. This approach avoids the PM CEMS calibration (i.e., PS 11
correlation) issues that can be exacerbated for Portland cement
installations. PM CEMS technology can be effective in monitoring
control device performance (see, e.g., 77 FR 9371 (February 16, 2012))
where the EPA established PM CPMS parametric operating limits for
electricity generating units).
    As a result, this proposed rule would require the installation and
operation of a PM CPMS for parametric monitoring associated with the
proposed PM standard. The source owner would not have to meet PS 11
requirements but would have to prepare and submit for approval, if
requested by a permitting authority, a site-specific monitoring plan to
apply sound practices for installing, calibrating and operating the PM
CPMS.
    Current PM CPMS have an operating principle based on in-stack or
extractive light scatter, light scintillation or beta attenuation. The
source owner or operator would need to examine the fuel and process
conditions of his stack as well as the capabilities of these devices
before selecting a particular CPMS technology. The reportable
measurement output from the PM CPMS may be expressed as milliamps,
stack

concentration or other raw data signal. For the purposes of this
proposed rule, the source owner would establish an operating limit
based on the highest PM CPMS hourly value collected during the most
recent PM compliance test (or other stack tests accepted as a
legitimate basis for compliance, as explained below). The source would
collect PM CPMS data continuously and calculate a 30 operating day
rolling average PM CPMS output value from the hourly PM CPMS data
collected during process operating hours and compare that average to
the site specific operating limit. For these reasons (i.e., 30 days to
mitigate the effects of measurement and emissions variability and using
the highest hourly average from the stack testing), the EPA believes
that use of the PM CPMS for parametric monitoring should not pose the
same technical issues as those underlying the proposed decision to base
compliance on PM CEMS measurements.
    We are proposing a number of consequences if the kiln PM monitoring
parameter is exceeded. First, the source owner will have 48 hours to
conduct an inspection of the control device and to take action to
restore the controls if necessary and 45 days to conduct a new PM
Method 5 compliance test to verify ongoing compliance with the PM
limit. Within 60 days complete the emissions sampling, sample analyses
and verification that the source is in compliance with the emissions
limit in accordance with the test procedures in either section 60.64 or
63.1349(b)(1). Also, determine an operating limit based on the PM CPMS
data collected during the performance test. Compare the recalculated
operating limit with the existing operating limit and, as appropriate,
adjust the numerical operating limit to reflect compliance performance.
Adjustments may include applying the most recently established highest
of the three test run hourly averages or combining the data collected
over multiple performance tests to establish a more representative
value. Apply the reverified or adjusted operating limit value from that
time forward.
    Second, the EPA is proposing that this proposed rule limit the
number of deviations of the site-specific CPMS limit leading to follow
up performance tests in any 12-month process operating period and an
excess of this number be considered to be a violation of the standard.
This presumption could be rebutted by the source, but would require
more than a Method 5 test to do so (e.g., results of physical
inspections). This additional information is necessary since a Method 5
test could not be conducted following the discovery of deviations and
would not necessarily represent conditions identical to those when the
deviations occurred. The basis for this part of the proposal is that
the site-specific CPMS limit could represent an emissions level higher
than the proposed numerical emissions limit since the PM CPMS operating
limit corresponds to the highest of the three runs collected during the
Method 5 performance test. Second, the PM CPMS operating limit reflects
a 30-day average that should represent an actual emissions level lower
than the three test run numerical emissions limit since variability is
mitigated over time. See 75 FR 54988 (September 9, 2010); 54975-76.
Consequently, we believe that there should be few if any deviations
from the 30-day parametric limit and there is a reasonable basis for
presuming that deviations that lead to multiple performance tests to
represent poor control device performance and to be a violation of the
standard.
    Therefore, the EPA is proposing that PM CPMS deviations leading to
more than four required performance tests in a 12-month process
operating period to be presumed a violation of this standard, subject
to the source's ability to rebut that presumption with information
about process and control device operations in addition to the Method 5
performance test results.
    Finally, the EPA is proposing that the NSPS for PM established
pursuant to section 111(bb) also be revised so that these limits are no
longer CEMS-based and reflect the resulting different numerical values
and averaging times. Although the NSPS for PM rests on a justification
independent of the NESHAP PM standard (see PCA v. EPA, 665 F. 3d at
192-93), the technical issues associated with the use of PM CEMS in
this industry are common to both standards and the proposed amendments,
therefore, appear appropriate for the NSPS as well. The EPA believes
that these proposed requirements represent Best Demonstrated Available
Technology for new cement kilns given that the standards remain
predicated on the performance of the best industry performers and the
costs remain those already found to be reasonable. See id. at 191-92
discussing and upholding the EPA's NSPS for PM.

E. Summary of Proposed Standards Resulting From Reconsideration

    The EPA is proposing the following revised MACT standards:

   Table 3--Proposed Existing and New Source Floors and Standards \a\
------------------------------------------------------------------------
                                    Existing source       New source
            Pollutant                  standard            standard
------------------------------------------------------------------------
Mercury.........................  55 lb/MM tons       21 lb/MM tons
                                   clinker.            clinker.
THC.............................  24 ppmvd..........  24 ppmvd.
PM..............................  0.07 lb/ton         0.02 lb/ton
                                   clinker (3-run      clinker (3-run
                                   test average).      test average).
HCl.............................  3 ppmvd...........  3 ppmvd.
Organic HAP.....................  12 ppmvd..........  12 ppmvd.
------------------------------------------------------------------------
\a\ Standards for mercury and THC are based on a 30-day rolling average.
  The standard for PM is based on a three run test. If using a CEMS to
  determine compliance with the HCl standard, the floor is also a 30-day
  rolling average. Organic HAP standards are discussed in section H
  below.

F. Standards for Fugitive Emissions From Clinker Storage Piles

    In the September 2010 rule, the agency established work practice
requirements to reduce fugitive emissions from outdoor clinker storage
piles. The agency had information that these storage piles emit HAP in
the form of fugitive PM containing HAP metals, so that regulation of
these sources was necessary. Because the emissions in question were
fugitive dusts for which measurement was not feasible, the agency
adopted work practices as the standard, specifically the work practice
standards and opacity emissions limits contained in California's South
Coast Air Quality Management District Rule 1156 as amended on March 6,
2009. Because there were only two plants which we could state
definitively had open storage piles and both were complying with Rule
1156, we believed that the regulatory standards under Rule 1156
constituted the floor level of control. The current promulgated work
practices consist of providing varying

degrees of enclosures or barriers to prevent wind erosion of the
storage piles. See generally 75 FR 54989 (September 9, 2010).
    In their reconsideration petition, the cement industry maintained
that the EPA did not provide sufficient notice of the standards it
might adopt for clinker storage piles. We agreed and granted
reconsideration. See 76 FR 28325 (May 17, 2011). The D.C. Circuit
stayed the standard pending the conclusion of the EPA's
reconsideration. See 665 F. 3d at 189.
    Industry also noted, correctly, that more than two plants are
potentially affected by clinker pile standards, so that the California
rule is not necessarily a floor level of control. To evaluate which
work practices are currently used in the industry, we requested data
from the industry on currently used work practices. We also undertook a
review of state permits to determine the level of controls to which
open clinker piles are currently subject. Based on this information,
the EPA is proposing to amend the work practices for clinker storage
piles.
1. What is a clinker pile?
    Clinker storage is necessary to allow near continuous kiln
operation and intermittent grinding and processing of the clinker.
Clinker storage is also necessary in the event of unplanned or planned
kiln shutdowns. Cement plants use silos, domes or other enclosure for
clinker storage. Additional clinker storage may also be necessary to
accommodate extended shutdown periods for kiln maintenance and/or
market conditions. When the conventional enclosed storage is not
adequate, clinker may be stored in outdoor piles. Unlike automated
systems for drawing down clinker from enclosed silos, these temporary
outdoor storage piles are drawn down using equipment such as front end
loaders or other reclaiming equipment. Outdoor clinker storage may be
temporary, lasting a few days or weeks and up to several months. There
are also open clinker piles that have been in existence for years and
are essentially permanent.
2. What are the proposed standards?
    We are proposing amended standards that will control HAP metal
emissions from open clinker piles. Because the emissions are fugitive,
we are proposing work practices instead of an emissions limit since it
is ``not feasible to prescribe or enforce an emission standard'' for
these emissions because, as fugitive emissions, they are not ``emitted
through a conveyance designed and constructed to emit or capture such
pollutant''. See CAA section 112 (h)(2)(A). The work practices would
apply to any open clinker piles regardless of the quantity of clinker
or the length of time that the clinker pile is in existence.
    According to industry stakeholders, virtually all Title V permits
oblige cement plant operators to ``minimize'' fugitive emissions
including those from open clinker piles. See Portland Cement
Reconsideration TSD, section 2, which is available in this rulemaking
docket. Our examination of relevant permits indicates that some permits
establish an opacity limit not to be exceeded in conjunction with
materials management. Others contain a ``no visible emissions''
limitation at the fence line of the facility. Industry stakeholders
state that to minimize fugitive emissions from open clinker piles,
plants employ a number of practices, the most common being to use water
sprays to form a concrete-like crust on the exposed surface of the
clinker pile. Clinker has cement like properties and when exposed to
water will hydrate and harden. The crust formed by this practice is
very effective at reducing fugitive emissions as long as the pile is
not disturbed. Another common practice is to cover clinker piles with
tarps, which may be held down with tires, which effectively minimizes
fugitive emissions. Some plants also use foam sprays on the exposed
surface of the pile, forming a coating which reduces or prevents
fugitive emissions.
    Based on our review of 88 state Title V permits, all but one permit
required one or a combination of the following control measures to
reduce fugitive emissions generally: Work practices, opacity or visible
emission limits, prohibitions against open clinker piles and some type
of general duty requirements to minimize fugitive dust emissions. Eight
of the permits contained requirements specific to open or outdoor
clinker piles. Eighteen permits contained standards that restricted
emissions more generally from outdoor storage piles including opacity
and visible emissions limits and general duty requirements to not
produce PM or dust emissions at the property line. Seventy-seven
permits contained facility-wide restrictions that applied to a variety
of fugitive sources at the cement facilities (e.g. roads, storage, raw
materials). In only one permit was it not clear that there were
requirements to minimize fugitive dust emissions.
    With the exception of total enclosure of all open clinker piles,
the EPA believes that the control measures in the permits are equally
effective in reducing fugitive emissions. These measures are,
therefore, consistent with section 112(d) controls and reflect a level
of performance analogous to a MACT floor. See CAA section 112(h)(1) (in
promulgating work practices, the EPA is to adopt standards ``which in
the Administrator's judgment [are] consistent with section (d) or (f)
of this section.'') The option of full enclosures, somewhat analogous
to a beyond-the-floor standard under section 112(d)(2), would be
extremely costly with minimum associated emissions reductions
incremental to the measures already undertaken (which already reduce
most or all of the fugitive emissions from these piles). The EPA,
therefore, is not proposing to mandate such a practice. Industry cost
estimates for a full enclosure with a capacity of 50,000 tons of
clinker range from $10-$25 million in capital cost and $400,000-
$500,000 annual operating cost (See Portland Cement Association,
Clinker Piles, September 7, 2011, available in the rulemaking docket).
We also are not proposing opacity or visible emission standards, for
several reasons. If work practices are properly implemented, we believe
fugitive emissions, including visible emissions, from clinker piles
will be effectively controlled. Such emission limits would also be
redundant with work practice requirements. Moreover, in many cases, the
temporary, short-term nature of clinker piles would make it impractical
to implement an emissions monitoring program that would be more
effective than the proposed work practices.
    We are proposing that one or more of the following control measures
be used when adding clinker to a pile, during on-going clinker storage,
and when reclaiming the clinker for processing, to minimize to the
greatest extent practicable fugitive dust emissions from open clinker
storage piles: Locating the source inside a partial enclosure (such as
a three sided structure with tarp), installing and operating a water
spray or fogging system, applying appropriate chemical dust suppression
agents on the pile, use of a wind barrier or use of a tarp. The owner
or operator must select, from the list provided, the control measure or
combination of control measures that are most appropriate for the site
conditions. We are allowing the owner or operator to select the most
appropriate control measure or combination of measures for their
situation.
    We are proposing that the owner or operator must include as part of
their operations and maintenance plan (required in Sec.  63.1347) the
fugitive dust

control measures that they will implement to control fugitive dust
emissions from open clinker piles. These control measures would apply
to the addition of clinker to the pile, on-going clinker storage and
reclaiming the clinker for processing.
    We are proposing the same standards for new sources as existing
sources. In the case of a clinker storage pile, there is no essential
difference between `new' and `existing'. These piles generally reflect
temporary storage situations, and are not analogous to building a one-
time stationary structure where there are opportunities for newly-
constructed entities that do not exist for existing entities. The EPA
consequently is proposing the same standards for both.

G. Affirmative Defense to Civil Penalties for Exceedances Occurring
During Malfunctions

    In response to comments, the EPA added to the September 9, 2010,
final rule an affirmative defense to civil penalties for exceedances of
emissions limits that are caused by malfunctions. Various environmental
advocacy groups, as well as the Portland Cement Association (PCA),
indicated that there had been insufficient notice of this provision.
The EPA agreed and granted reconsideration. See 76 FR 28325 (May 17,
2011). We are proposing to retain the affirmative defense on
reconsideration. This provision seeks to balance a tension, inherent in
many types of air regulation, to ensure adequate compliance while
simultaneously recognizing that despite the most diligent of efforts,
emission limits may be exceeded under circumstances beyond the control
of the source. The EPA must establish emission standards that ``limit
the quantity, rate, or concentration of emissions of air pollutants on
a continuous basis.'' See 42 U.S.C. 7602(k) (defining ``emission
limitation and emission standard''). See generally Sierra Club v. EPA,
551 F.3d 1019, 1021 (D.C. Cir. 2008) Thus, the EPA is required to
ensure that section 112 emissions limitations are continuous. The
affirmative defense for malfunction events meets this requirement by
ensuring that even where there is a malfunction, the emission
limitation is still enforceable through injunctive relief. Although
``continuous'' limitations, on the one hand, are required, there is
also case law indicating that in many situations it is appropriate for
the EPA to account for the practical realities of control technology.
For example, in Essex Chemical v. Ruckelshaus, 486 F.2d 427, 433 (D.C.
Cir. 1973), the D.C. Circuit acknowledged that in setting standards
under CAA section 111 ``variant provisions'' such as provisions
allowing for upsets during startup, shutdown and equipment malfunction
``appear necessary to preserve the reasonableness of the standards as a
whole and that the record does not support the `never to be exceeded'
standard currently in force.'' See also, Portland Cement Association v.
Ruckelshaus, 486 F.2d 375 (D.C. Cir. 1973). Though intervening case law
such as Sierra Club v. EPA and the CAA 1977 amendments undermine the
relevance of these cases today, they support the EPA's view that a
system that incorporates some level of flexibility is reasonable. The
affirmative defense simply provides for a defense to civil penalties
for excess emissions that are proven to be beyond the control of the
source. By incorporating an affirmative defense, the EPA has formalized
its approach to upset events. In a Clean Water Act setting, the Ninth
Circuit required this type of formalized approach when regulating
``upsets beyond the control of the permit holder.'' Marathon Oil Co. v.
EPA, 564 F.2d 1253, 1272-73 (9th Cir. 1977); see also, Mont. Sulphur &
Chem. Co. v. United States EPA, 2012 U.S. App. LEXIS 1056 (Jan 19,
2012) (rejecting industry argument that reliance on the affirmative
defense was not adequate). But see, Weyerhaeuser Co. v. Costle, 590
F.2d 1011, 1057-58 (D.C. Cir. 1978) (holding that an informal approach
is adequate). The affirmative defense provisions give the EPA the
flexibility to both ensure that its emission limitations are
``continuous'' as required by 42 U.S.C. Sec.  7602(k), and account for
unplanned upsets and thus support the reasonableness of the standard as
a whole.
    Petitions filed by environmental advocacy groups question the EPA's
authority to promulgate the affirmative defense arguing, among other
things, that the affirmative defense is inconsistent with the
provisions of CAA sections 113(e) and 304(b) governing penalty
assessment and citizen suits, respectively. The EPA's view is that the
affirmative defense is not inconsistent with CAA section 113(e) or 304.
Section 304 gives district courts' jurisdiction ``to apply appropriate
civil penalties.'' Section 113(e)(1) identifies the factors that the
Administrator or a court shall take into consideration in determining
the amount of a penalty to be assessed, once it has been determined
that a penalty is appropriate. The affirmative defense regulatory
provision is not relevant to the amount of any penalty to be assessed.
If a court determines that the affirmative defense elements have been
established, then a penalty is not appropriate and penalty assessment
pursuant to the section 113(e)(1) factors does not occur.
    In exercising its authority under section 112 to establish emission
standards (at a level that meets the stringency requirements of section
112), the EPA necessarily defines conduct that constitutes a violation.
The EPA view is that the affirmative defense is part of the emission
standard and defines two categories of violation. If there is a
violation of the emission standard and the source demonstrates that all
the elements of the affirmative defense are met, only injunctive relief
is available. All other violations of the emission standard are subject
to injunctive relief and penalties. A citizen suit claim under section
304 allows citizens to commence a civil action against any person
alleged to be in violation of ``an emission standard or limitation
under this chapter.'' The CAA, however, allows the EPA to establish
such ``enforceable emission limitations.'' Thus, the citizen suit
provision clearly contemplates enforcement of the standards that are
defined by the EPA. As a result, where the EPA defines its emissions
limitations and enforcement measures to allow a source the opportunity
to prove its entitlement to a lesser degree of violation (not subject
to penalties) in narrow, specified circumstances, as the EPA did here,
penalties are not ``appropriate'' under section 304.
    The EPA solicits comments on this issue of the EPA's authority to
promulgate an affirmative defense. The EPA's view is that an
affirmative defense to civil penalties for exceedances of applicable
emission standards during periods of malfunction appropriately balances
competing concerns. On the one hand, citizen enforcers are concerned
about additional complications in their enforcement actions. On the
other hand, industrial sources are concerned about being penalized for
violations caused by malfunctions that they could not have prevented
and were otherwise appropriately handled (as reflected in the
affirmative defense criteria). The EPA has used its section 301(a)(1)
authority to issue regulations necessary to carry out the Act in a
manner that appropriately balances these competing concerns. However,
the EPA also solicits comment on alternatives to, or variations on, the
affirmative defense provisions promulgated in the 2010 final rule.
    In its petition for reconsideration, the PCA expressed support for
the affirmative defense, but maintains that

``the affirmative defense process that EPA codified in the final rules
is cumbersome and will be exceedingly difficult for facilities to
employ.'' The EPA is soliciting comment on the terms and condition of
the affirmative defense. In recent rules promulgated under section 112
and 129, the EPA has revised certain terms and conditions of the
affirmative defense in response to concerns raised by various
commenters. The EPA is proposing to adopt those same revisions in this
proposed rule. The EPA is proposing to revise the affirmative defense
language to delete ``short'' from section 63.1344(a)(1)(i), because
other criteria in the affirmative defense require that the source
assure that the duration of the excess emissions ``were minimized to
the maximum extent practicable.'' The EPA is also proposing to delete
the term ``severe'' in the phrase ``severe personal injury'' in
63.1344(a)(4) because we do not think it is appropriate to make the
affirmative defense available only when bypass was unavoidable to
prevent severe personal injury. In addition, the EPA is proposing to
revise section 63.1344(a)(8) to add ``consistent with good air
pollution control practice for minimizing emissions.'' The EPA is also
proposing to revise the language of 63.1344(a)(9) to clarify that the
purpose of the root cause analysis is to determine, correct and
eliminate the primary cause of the malfunction. The root cause analysis
itself does not necessarily require that the cause be determined,
corrected or eliminated. However, in most cases, the EPA believes that
a properly conducted root cause analysis will have such results.
Further, the EPA is proposing to revise 63.1344(b) to state that
``[t]he owner or operator seeking to assert an affirmative defense
shall submit a written report to the Administrator in a semiannual
report with all necessary supporting documentation, that it has met the
requirements set forth in section 63.1354(c) of this subpart.'' This
report must be included in the first semiannual report, required by
section 63.1354(b)(9), after the initial occurrence of the violation of
the relevant standard. If the semiannual report is due less than 45
days after the initial occurrence of the violation, the affirmative
defense report may be included in the second semiannual report due
after the initial occurrence of the violation of the relevant standard.
See proposed regulatory text for other proposed minor wording changes
to improve clarity.

H. Continuously Monitored Parameters for Alternative Organic HAP
Standard (With THC Monitoring Parameter)

    In the September 2010 final rule, the EPA promulgated an
alternative standard for non-dioxin organic HAP, based on measuring the
organic HAP itself rather than the THC surrogate. Section 63.1343(b)(1)
provides two options for meeting a standard for organic HAP. One is to
meet a THC standard of 24 ppmvd; the other is to meet a limit of 9
ppmvd of total organic HAP. This equivalent alternative standard is
intended to 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. The specific organic compounds that are to be measured
to determine compliance with the equivalent alternative standard are
benzene, toluene, styrene, xylene (ortho-, meta-, and para-),
acetaldehyde, formaldehyde and naphthalene. Compliance with the
equivalent alternative standard under the September 2010 standard will
be determined through organic HAP emissions testing using EPA Method 18
or 320, as appropriate for the compound of interest. The 2010 rule
further requires that each source complying with the alternative
standard establish a site-specific THC limit to be met continuously.
The site-specific THC limit will be measured as a 30 day rolling
average, with an annual compliance test requirement. It would be
correlated with the organic HAP limit and is therefore not tied to the
THC standard of 24 ppmvd. We granted reconsideration on the level of
this site-specific THC limit used as a continuously monitored parameter
for those sources selecting the alternative HAP compliance method. See
76 FR 28318 (May 17, 2011).
    Since THC includes compounds that are not considered to be
hazardous, either of the two standards are considered to be reasonable.
    While the September 2010 final rule required an organic HAP limit
of 9 ppmvd, a recent review of the method detection limits used to
measure organic HAP revealed that three times the representative method
detection level (3*RMDL) is actually 12 ppmvd, therefore, we propose to
revise the alternative organic HAP limit to 12 ppmvd. As discussed in
the final rule, the expected measurement imprecision for an emissions
value at or near the method detection level is about 40 to 50 percent
and decreases to a consistent 10 to 15 percent for values that are
three times the method detection level. See 75 FR 54984 (September 9,
2010); see also section D above. Thus, measured values less than three
times the representative method detection level are highly uncertain
and therefore not reasonable for compliance determinations. The 3*RMDL
of 12 ppmvd was determined as follows: we determined method detection
capabilities for Method 320 and Method 18 as appropriate for the
various compounds (e.g., Method 320 for aldehydes, Method 18 for
aromatic hydrocarbons (arenes)). This approach is consistent with
procedures practiced by the better performing testing companies and
laboratories using sensitive analytical procedures. We determined for
each of the organic HAP the expected method detection level for the
respective method based on internal experience and method capabilities
reported by testing companies. With these reported values, we
identified the resulting mean of the method detection levels, adjusted
them for dilution and moisture, summed them, and then multiplied the
sum by three to determine the representative detection level (RDL). The
resulting RDL value was found to be 11.2 ppmvd @ 7 percent oxygen
(O2), dry. This value is greater than the final 9 ppmvd @ 7
percent O2, dry, in the final rule. We are, therefore,
proposing to adjust the total organic HAP limit to 12 ppmvd @ 7 percent
O2, dry (rounded up from the 11.2 ppm RDL). At this level,
we believe that currently available emissions testing procedures and
technologies can be used to provide measurements of sufficient
certainty for sources to demonstrate compliance. A detailed discussion
of the use of the RDL to arrive at the proposed organic HAP limit is
found in the Portland Cement Reconsideration TSD, section 3, which can
be found in the docket for this rulemaking.
    A consequence of this analysis is that the accuracy of the analytic
methods for organic HAP appear to be insufficient to allow sources to
scale up their site-specific THC limit based on the degree to which the
measured organic HAP levels were below the organic HAP limit--the
organic HAP limit, even as proposed to be revised, is at the reliable
limit of detection as just explained. Therefore, this proposed rule
retains the provision whereby the site-specific THC operating parameter
is established at the same time the performance test is conducted for
organic HAP. If the site-specific THC operating parameter is

exceeded, then the kiln would have to be retested to determine
compliance with the organic HAP limit. This proposed rule would further
require that the tests for organic HAP and THC be repeated annually to
establish a new annual site-specific THC parameter reflecting the
organic HAP level. We also are proposing, similar to the PM compliance
test procedure, that the highest 1-hour average THC concentration
measured during the 3-hour organic HAP test, be used as the site-
specific THC parameter, and are allowing facilities to extend the
testing time (or number of tests) if they believe extended testing is
required to adequately capture THC variability over time. The EPA
specifically solicits comment on the changes on the organic HAP limit.
In addition, we solicit comment on if it would it be appropriate to
allow sources to scale up their site-specific THC limit based on the
degree to which the measured organic HAP levels are below the organic
HAP limit.

I. Allowing Sources With Dry Caustic Scrubbers To Comply With HCl
Standard Using Performance Tests

    To demonstrate compliance with the HCl emissions limit, the
September 2010 final rule allows sources equipped with wet scrubbers to
comply with the HCl standard by means of periodic performance tests
rather than with continuous monitoring of HCl with a CEMS (see Sec.
63.1349(b)(6)). We reasoned that a source that uses a limestone wet
scrubber for HCl control will have minimal HCl emissions even if kiln
inputs change because limestone wet scrubbers are more efficient in
removing HCl than they are required to be, to meet the standard.
Sources electing to comply by means of stack tests must establish
continuously monitored parameters including liquid flow rate, pressure
and pH. Sources using a limestone wet scrubber are required to perform
an initial compliance test using Method 321 in Appendix A to 40 CFR
part 63 and to test every 30 months thereafter.
    In their petition, industry stakeholders indicated that this
compliance option should not be limited to wet scrubber equipped units,
but should also be available for units equipped with caustic scrubbers,
in part because some sources will be equipped with dry scrubbers (due
to water shortages) and should have the same operating flexibilities as
wet scrubber equipped kilns.
    A recent review of data from a vendor of acid gas controls using a
standard hydrated lime and a high performance hydrated lime at a U.S.
cement manufacturing plant, revealed that HCl removal from dry
scrubbers on kilns ranged from 90 to 95 percent HCl removal, depending
on lime injection rates (Lhoist North America, Cement Industry
Experience, DSI for Acid Gas Control, October 5, 2011). The results
also showed the plant could meet the 3 ppm HCl limit. The EPA also
evaluated HCl removal efficiency using dry sprayer absorber with a
fabric filter as part of the electric utility generating MACT
rulemaking. Removal efficiencies ranged from 95 percent to nearly 100
percent with an average of about 99.8 percent (Hutson to Nizich, HCl
control using SDA/FF, November 29, 2011). In addition, information from
the National Lime Association (http://www.lime.org/uses_of_lime/environmental/flue_gas.asp) and the Institute for Clean Air Companies
(http://www.icac.com/i4a/pages/index.cfm?pageid=3401) report HCl
emissions reductions using dry lime injection technology of 95 to 99
percent from coal-fired boilers in the electric utility industry, from
municipal waste-to-energy facilities and from other industries. In the
secondary aluminum industry, reductions in HCl emissions greater than
99 percent have been achieved (National Lime Association, Flue Gas
Desulfurization, http://www.lime.org/uses_of_lime/environmental/flue_gas.asp).
    Given these high reported removal efficiencies, we propose to
extend the same option provided to kilns equipped with wet scrubbers to
dry scrubber-equipped kilns. Thus, kilns with either type of scrubber
could demonstrate compliance with the HCl limit by means of an initial
and periodic stack test rather than with continuous compliance
monitoring with a CEMS. In order to assure that the dry lime injection
equipment is operated effectively between tests, the proposed amendment
would require that the lime injection rate used during the performance
test demonstrating compliance with the HCl limit be recorded and then
continuously monitored between performance tests to show that the
injection rate remains at or above the rate used during the performance
test.
    We are also proposing an additional alternative for all kilns
equipped with a dry or wet scrubber (and, under this proposal, could
therefore do periodic HCl performance testing and parametric
monitoring). Where either wet or dry scrubbers are used, we are
proposing that an owner or operator would have the option of using
SO2 monitoring as a continuously monitored parameter for
purposes of compliance monitoring. Because HCl is a water-soluble
compound and because it has a large acid dissociation constant (i.e.,
HCl is a strong acid), it will be more rapidly and readily removed than
SO2 from a gas stream treated with either caustic sorbents
(e.g., lime, limestone) or plain water. We acknowledge that at proposal
(see 74 FR 21154, May 6, 2009) we rejected setting a standard (as
opposed to a continuously monitored parameter) that used SO2
as a surrogate for HCl because we had no data that demonstrated a
direct link between HCl emissions and SO2 emissions.
However, pilot-scale tests by the EPA at its Multi-pollutant Control
Research Facility support the use of the more easily measured
SO2 as a surrogate for HCl where either wet or dry scrubbers
are used. See Docket item EPA-HQ-OAR-2009-0234-3893. Further, we are
aware that there are existing kilns equipped with SO2 CEMS
and that this monitoring technology is less expensive and more mature
than HCl CEMS. Thus, we are proposing that SO2 is an
indicator for HCl compliance, and that monitoring the emissions of
SO2 will provide a reliable indication of HCl removal,
making SO2 monitoring an appropriate parameter for
monitoring continuing compliance.
    Owners or operators of kilns equipped with dry or wet scrubbers
that choose to use SO2 monitoring would need to conduct an
initial performance test for HCl and establish the SO2
operating limit equal to the highest 1 hour average recorded during the
HCl performance test, so that there is an indication of proper
operation of the HCl control device. The owner or operator of a kiln
controlled using either a dry or wet scrubber that chooses to monitor
SO2 would not be required to also establish continuously
monitored parameters reflecting the performance test results, such as
lime injection rate for a dry scrubber and liquid flow rate, pressure
and pH for a wet scrubber. Deviation from any established parameter
level or established SO2 operating level would trigger a
requirement to retest for HCl in order to verify compliance with the
HCl limits and to verify or re-establish the parameter levels.
    At a minimum, a repeat performance test to confirm compliance with
the HCl emissions limit and to reset the SO2 limit and
monitoring parameters is required every 5 years. We are requesting
comment on the efficacy of continuously monitoring SO2 as a
continuously monitored parameter in lieu of continuously monitoring HCl
control device parameters, and also solicit comment on testing every 30
months for HCl for purposes of

monitoring compliance with the HCl emissions limit.

J. Alternative PM Limit

    Some kilns combine kiln exhaust gas with exhaust gas from other
unit operations, such as the clinker cooler, as an energy saving
practice. The September 2010 final rule sought to accommodate
commingled flows from the kiln and clinker cooler by providing a site
specific PM limit. See section 63.1343(b)(2). In its reconsideration
petition, the PCA pointed out, however, that other flows besides the
exhaust gas flow from the clinker cooler can be commingled as well. The
petitioner provided the example of coal mill exhaust and exhaust from
an alkali by-pass as instances of additional flows that can be
commingled with the exhaust gas flow from the kiln. The petitioner
observed that without an allowance for these additional flows, the site
specific PM limit is stricter than the EPA intended (since the PM
concentration will be divided by a lower number in the implementing
equation), and penalizes the energy-saving practice of commingling
these flows.
    The agency agreed with the petitioner that the alternative PM
equations for existing and new sources contained in the final rule do
not adequately account for commingled exhaust gas flows from sources
other than the clinker cooler, and granted reconsideration for this
reason. See 76 FR 28325 (May 17, 2011). We believe that although the
form of the equation is correct, the equation is not written to
accommodate sources other than exhaust gases from the clinker cooler.
We are proposing to revise the equation so that it includes exhaust gas
flows for all potential sources that would potentially be combined,
including exhausts from the kiln, the alkali bypass, the coal mill, and
the clinker cooler, for an existing kiln, the EPA is proposing the
following equation:

PMalt = 0.0060 x 1.65 x (Qk + Qc +
Qab + Qcm)/(7000)

Where:

PMalt = The alternative PM emission limit for commingled
sources.
0.006 = The PM exhaust concentration (gr/dscf) equivalent to 0.07 lb
per ton clinker where clinker cooler and kiln exhaust gas are not
combined.\12\
---------------------------------------------------------------------------

    \12\ Note that this figure would change correspondingly if the
EPA were to amend the existing source PM standard. The same is true
of the PM term in the new source equation.
---------------------------------------------------------------------------

1.65 = The conversion factor of lb feed per lb clinker.
Qk = The exhaust flow of the kiln (dscf/ton raw feed).
Qc = The exhaust flow of the clinker cooler (dscf/ton raw
feed).
Qab = The exhaust flow of the alkali bypass (dscf/ton raw
feed).
Qcm = The exhaust flow of the coal mill (dscf/ton raw
feed).
7000 = The conversion factor for grains (gr) per lb.

If exhaust gases for any of the sources contained in the equation are
not commingled and are exhausted through a separate stack, their value
in the equation would be zero. The alternative PM equation for new
sources is identical to the existing source equation except the PM
exhaust concentration used in the equation is 0.002 grains per dry
standard cubic foot, which is equivalent to the new source PM limit of
0.02 lb/ton clinker.

K. Standards During Startup and Shutdown

    In the final NESHAP, the EPA established separate standards for
startup and shutdown which differ from the main standards. These
standards require kilns to meet numerical limits for each pollutant
regulated by the rule, each standard to be measured using a CEMS over
an accumulative 7-day rolling average. 75 FR 54991 (September 9, 2010).
Industry petitioned the EPA to reconsider these standards claiming lack
of notice, but the EPA denied these petitions because the agency had
already provided ample opportunity for comment which petitioners had
used. See 76 FR 28323 (May 17, 2011). The D.C. Circuit dismissed all
challenges to these startup and shutdown provisions (see 665 F 3d at
189). The EPA did grant reconsideration on several technical issues
related to startup and shutdown--certain aspects of CEM-based
monitoring of mercury and PM during startup and shutdown--issues which
would be moot if the EPA adopts the approach proposed below--and having
an HCl limit of zero for kilns not equipped with CEMS (see 76 FR 28325
(May 17, 2011)).
    The EPA is proposing to retain the startup and shutdown standards
for mercury and THC, to amend the startup and shutdown standards for PM
to be consistent with the proposed numeric levels in this proposal, and
to amend the level of the startup and shutdown standard for HCl to be 3
ppm in all circumstances.
    The EPA is further proposing to clarify that startup begins when
the kiln's induced fan is turned on and continues until continuous raw
material feed is introduced into the kiln. Shutdown begins when feed to
the kiln is halted. Thus, during startup and shutdown, as defined, a
kiln would not be firing coal or coke and would not be introducing feed
material into the kiln continuously. HAP emissions from cement kilns
are attributable almost entirely to one or the other of these feeds,
with raw materials contributing the great preponderance. In addition,
kilns burn fuels during startup and shutdown which are cleaner than
coal and coke (natural gas is used for the most of the startup). Thus,
HAP emissions during startup and shutdown necessarily should be far
less than the numerical limits in the standards since the kiln will not
be introducing raw materials, and will be burning fuels which are
cleaner than its normal fuels.
    Accordingly, the EPA is further proposing to change the means of
monitoring for compliance with the startup and shutdown standards.
Rather than require monitoring by a CEM or by stack testing, the EPA is
proposing that a source keep records of the volumes of fuels introduced
into the kiln during startup and shutdown to verify that raw materials
are not introduced into the kiln, although, by definition, if raw
materials are introduced continuously into the kiln, the kiln is not
operating in startup and shutdown and the monitoring requirements of
the main standards would therefore apply. Kiln owners and operators
would then make conservative assumptions as to the combustion
efficiency of the kiln so as to reasonably estimate destruction of
organics, and include mass balance calculations showing that the
startup/shutdown standards would not be exceeded.
    These proposed recordkeeping requirements would serve as the basis
for compliance monitoring. The EPA believes that these proposed
recordkeeping requirements are both sufficient to yield reliable
information for the startup and shutdown periods, and to establish a
source's compliance or non-compliance with the startup and shutdown
standards. The EPA also believes that this proposed requirement would
satisfy the requirements of 40 CFR section 70.6(c)(1) which requires
that Title V permits shall contain ``monitoring * * * requirements
sufficient to assure compliance with the terms and conditions of the
permit.''
    The EPA is further proposing that the standard for HCl during
startup and shutdown be 3 ppmvd under all circumstances, and thus is
proposing to eliminate the current provision that the startup and
shutdown standard be zero for kilns measuring compliance by means other
than a CEM. As shown in the petitions for reconsideration, HCl can be
formed even when normal fuels and raw materials are not being

introduced into the kiln (for example, from residual chlorides in the
kiln refractory). See PCA Petition for Reconsideration Exh. 1.
Consequently, the promulgated limit of zero is technically
inappropriate, and the EPA is proposing to amend it to 3 ppmvd, the
same standard which applies in all other operating modes. Monitoring
during startup and shutdown would be accomplished by recordkeeping, as
explained above.
    The EPA also solicits comment on whether the numeric standards
during startup and shutdown should be amended to provide work
practices, rather than numeric standards. Work practices could require
operation of emission control devices during startup and shutdown,
minimizing the time periods of startup/shutdown, and following
manufacturer's best practices. We rejected work practices for startup
and shutdown periods in the 2010 final rule because the commenters
requesting such standard failed to demonstrate why it is ``not feasible
* * * to prescribe or enforce an emission standard'' for mercury, THC,
PM and HCl during startup and shutdown at cement kilns, within the
meaning of section 112(h) of the Act. See NESHAP from the Portland
Cement Manufacturing Industry Response to Comments Received on Proposed
Rule Published on May 6, 2009, 74 FR 21135, August 6, 2010 at p. 184.

L. Coal Mills

    Cement kilns burn coal as their main fuel, and mill the coal before
firing it. From the standpoint of air emissions, these coal mills are
sometimes physically distinct from the cement kiln, generating
emissions solely attributable to the coal mill and emitting exhaust
through a dedicated stack. However, some kilns are configured so that
coal mill emissions are commingled with kiln exhaust and the emissions
are discharged through the main kiln stack. Finally, there are some
configurations whereby kiln emissions are routed to the coal mill and
discharged through the coal mill stack. This part of the preamble
discusses the regulatory treatment of these different scenarios.
    First, the EPA has promulgated new source performance standards (40
CFR part 60 subpart Y) for coal mills. See 74 FR 51952 (October 8,
2009). These standards apply to coal mills, including coal mills at
cement manufacturing facilities, which emit through a dedicated stack.
Subpart Y standards do not apply to coal mills at cement facilities
whose only heat source is kiln exhaust. See section 60.251(j)
(definition of indirect thermal dryer). This leaves ambiguous, or
partially ambiguous, the regulatory treatment of the second and third
situations mentioned above: A kiln whose coal emissions are discharged
through the main kiln stack, and the coal mill which receives some
exhaust from the cement kiln so that some portion of the coal mill
exhaust can reflect cement kiln emissions. Because we did not address
these issues in the 2010 final NESHAP for Portland cement kilns, we
granted reconsideration in order to do so. See 76 FR 28326 (May 17,
2011).
    A cement kiln which commingles emissions from its coal mill with
all other emissions and discharges through kiln emission points would
have to meet all of the NESHAP. In the case of PM, the additional flow
from the coal mill would be accounted for in the equation used to
determine PM contributions from commingled flows. See section K above.
    In the case of a coal mill which receives and discharges some of
the cement kiln exhaust, the regulatory concern is that this re-routing
of kiln exhaust not result in uncontrolled HAP emissions.
    Our basic principle for this situation could be that the kiln
demonstrate that it is meeting all of the NESHAP standards for
pollutants not regulated under the subpart Y coal mill standard, that
is mercury, THC and HCl. Because the subpart Y standards contain a PM
standard predicated on use of fabric filter control technology, we do
not believe it necessary to account for diverted PM emissions.
    We are soliciting comment on the following compliance mechanism for
the mercury, THC and HCl standards in this situation: The sum of the
mercury, THC and HCl in the kiln exhaust diverted to the coal mill, and
the kiln exhaust exhausted in the main kiln stack, must not exceed the
subpart LLL NESHAP emission limits for each respective HAP or HAP
surrogate. Under this approach, the rule could contain requirements to
document the contribution of the emissions diverted to the coal mill.
With respect to THC and HCl, because coal may be a source of these
emissions, we are soliciting comment on a requirement that performance
tests for THC and HCl be performed upstream of the coal mill. For
mercury, we are soliciting comment on a requirement that tests be
required downstream to account for any mercury removal in the coal mill
air pollution control device (APCD), and to avoid double counting
emissions of mercury from mercury that becomes re-entrained in the
coal, which is then burned by the cement kiln (which emissions are
otherwise accounted for in the NESHAP).
    We note further that an analogous situation is when a cement kiln
has an alkali bypass which receives and exhausts emissions from the
kiln. We are proposing that these emissions be subject to controls
reflecting the same principle--the total emissions of the kiln and
alkali bypass must meet the subpart LLL NESHAP. We are also proposing
to use the same monitoring procedures to document compliance. The one
(slight) exception is for PM. Because there is no independent PM
standard for an alkali bypass (unlike the situation for coal mills,
where subpart Y regulates PM emissions), the summed PM emissions from
the kiln and alkali bypass would have to be equal to or less than the
PM limit in the subpart LLL NESHAP. Tests for PM from the alkali bypass
would be downstream of the alkali bypass APCD to account for those
emission reductions. Though we are not proposing the coal mill
requirements in this action, we have placed the appropriate regulatory
text in the proposed rule language to allow comment on actual rule
language.
    We expand on these monitoring provisions below.
    1. Mercury. Although mercury from the main stack is monitored using
a CEMS, there is no need for such monitoring for the gas streams from
the coal mill. The gas stream to the coal mill is small in comparison
to the kiln exhaust, operation of the coal mill is intermittent, and
the cost of requiring additional CEMS for coal mills would be overly
burdensome. Instead, the performance tests for mercury could be
conducted at such a coal mill once per year, and, as explained above,
that the tests be conducted downstream of the coal mill. Performance
tests for mercury could be conducted using either Methods 29 or 30B in
Appendix A-8 to 40 CFR Part 60. These performance tests could be
required annually until the tested mercury levels are below the method
detection limits for two consecutive years, after which tests may be
conducted every 30 months. If test results at any time exceed the
method detection limit, annual performance testing could again be
required until mercury levels are below the method detection limit for
two consecutive years. The results of the performance test could then
be summed with the emissions from the kiln stack to determine
compliance with the mercury emissions limit. Since kiln stack emissions
are measured continuously with a CEMS, the coal gas emissions could be
normalized on both a CEMS and production basis (lb/MM ton

clinker) in order to be summed with the kiln stack emissions. To do so,
the flow rate to the coal mill could be continuously monitored. Using
the results of the annual performance test and the continuous flow rate
from the coal mill, the owner or operator could develop a mercury
hourly mass emission rate for the coal mill. Hourly mercury emissions
from the coal mill could be summed with the mercury emissions from the
kiln to determine continuous compliance as follows:

((QabxCab) + (QcmxCcm) + (QksxCks))/P <= MACT Limit

Where:

Qab = Alkali bypass flow rate (volume/hr)

Cab = Alkali bypass concentration (lb/dscf)
Qcm = Coal mill flow rate (volume/hr)
Ccm = Coal mill concentration (lb/dscf)
Qks = Kiln stack flow rate (volume/hr)
Cks = Kiln stack concentration (lb/dscf)
P = Kiln production rate (million tons clinker/hr)
MACT Limit = Limit for mercury (55 lb mercury/MM tons clinker)

    This equation requires all values to be at or corrected to 7
percent O2.
    Thus, if the normalized test results at the coal mill control
device outlet shows mercury emissions of 10 lb/MM tons clinker,
emissions from the kiln should be less than 45 lb/MM tons of clinker to
be in compliance with the proposed kiln mercury emissions limit. See
section 63.1350(k)(5).
    For kilns also equipped with an alkali bypass, the same procedure
as that for the coal mill would apply. Where a portion of kiln gases
are diverted to a coal mill and to an alkali bypass, emissions from the
coal mill and alkali bypass would be tested, normalized and summed and
with the mercury emissions from the kiln to determine compliance with
the emissions limit.
    2. THC and HCl. Because THC and HCl are concentration-based limits,
the compliance demonstration could differ in certain details from the
procedure described above for the production based limits for mercury.
Kiln stack emission limits (to be continuously monitored) could be
calculated taking into consideration the volumetric exhaust gas flow
rates and concentrations of all applicable effluent streams (kiln
stack, coal mill, and alkali bypass) for the kiln unit as follows:
[GRAPHIC] [TIFF OMITTED] TP18JY12.000

Where:

Qab = Alkali bypass flow rate (volume/hr)
Cab = Alkali bypass concentration (ppmvd)
Qcm = Coal mill flow rate (volume/hr)
Ccm = Coal mill concentration (ppmvd)e
Qks = Kiln stack flow rate (volume/hr)
Cks = Kiln stack concentration (ppmvd)
MACT Limit = Limit for THC or HCl (ppmvd)

This equation requires all values to be at or corrected to 7 percent
O2.\13\
---------------------------------------------------------------------------

    \13\ The proposed approach is conceptually similar to that for
PM from multiple sources discussed in K. above--an equation which
accounts for the flow-weighted concentration of PM from all sources.

    In order to determine the flow rates and concentrations of THC and
HCl in the coal mill and alkali bypass streams, the source could test
annually using the appropriate test method and could monitor the flow
rate of the kiln stack with CMS. For HCl, the performance test could be
performed using Method 321 in Appendix A to 40 CFR Part 63. For
measurement of THC, Method 25A in Appendix A-7 to 40 CFR Part 60 could
be required. With these data, the concentration of THC and HCl that
must be monitored in the CEMS in order to demonstrate compliance with
the kiln MACT limit under this proposal can be calculated by solving
for Cks (kiln stack concentration) from the equation above, as shown:
[GRAPHIC] [TIFF OMITTED] TP18JY12.001

    This equation is based on the following:
     The total allowable mass emissions of THC and HCl for the
kiln unit can be determined with the sum of all flow rates (coal mill,
alkali bypass and kiln stack) and the applicable NESHAP limit (THC or
HCl) concentration. This yields the total allowable mass emissions per
unit of time for the kiln unit according to the MACT limits and the
site specific flow rates for the coal mill, alkali bypass and kiln
stack.
     By testing the coal mill and alkali bypass streams for
concentration and flow rate, the actual mass of THC and HCl emitted per
unit of time can be determined.
     Subtracting the actual mass emissions of THC and HCl
leaving the coal mill and alkali by pass from the total allowable mass
emissions for the kiln unit determines the remainder of allowable mass
emissions that can be emitted through the kiln stack.
     With knowledge of the flow rate at the kiln stack
(measured by CMS) and the allowable mass emissions (i.e. remainder)
that can be emitted through the kiln stack, a site specific
concentration can be determined. The equation above provides a
simplified approach to determining this value.
    The following example indicates how compliance could be
demonstrated. In this example, we assume a kiln stack, coal mill and
alkali bypass with the following volumetric flow rates and THC
concentrations:

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

----------------------------------------------------------------------------------------------------------------
       Effluent stream                   Flow
                                  THC concentration      Notes     MACT LIMIT
                                         rate
                                       (ppmvd)                       (ppmvd)
                                      (dscm/hr)
                                       (@7% O2)                     (@7% O2)
----------------------------------------------------------------------------------------------------------------
Alkali Bypass................  Qab....          38,233  Cab....              56  Determined                   24
                                                                                through test.
Coal Mill....................  Qcm....          57,349  Ccm....              56  Determined
                                                                                through test.