[Federal Register: May 6, 2009 (Volume 74, Number 86)]
[Proposed Rules]
[Page 21135-21192]
[DOCID:fr06my09-25]

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Part III

Environmental Protection Agency

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40 CFR Parts 60 and 63

National Emission Standards for Hazardous Air Pollutants From the
Portland Cement Manufacturing Industry; Proposed Rule

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 60 and 63

[EPA-HQ-OAR-2002-0051; FRL-8898-1]
RIN 2060-AO15

National Emission Standards for Hazardous Air Pollutants From the
Portland Cement Manufacturing Industry

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: EPA is proposing amendments to the current National Emission
Standards for Hazardous Air Pollutants (NESHAP) from the Portland
Cement Manufacturing Industry. These proposed amendments would add or
revise, as applicable, emission limits for mercury, total hydrocarbons
(THC), and particulate matter (PM) from kilns and in-line kiln/raw
mills located at a major or an area source, and hydrochloric acid (HCl)
from kilns and in-line kiln/raw mills located at major sources. These
proposed amendments also would remove the following four provisions in
the current regulation: the operating limit for the average hourly
recycle rate for cement kiln dust; the requirement that cement kilns
only use certain type of utility boiler fly ash; the opacity limits for
kilns and clinker coolers; and the 50 parts per million volume dry
(ppmvd) THC emission limit for new greenfield sources. EPA is also
proposing standards which would apply during startup, shutdown, and
operating modes for all of the current section 112 standards applicable
to cement kilns.
    Finally, EPA is proposing performance specifications for use of
mercury continuous emission monitors (CEMS), which specifications would
be generally applicable and so could apply to sources from categories
other than, and in addition to, portland cement, and updating
recordkeeping and testing requirements.

DATES: Comments must be received on or before July 6, 2009. If any one
contacts EPA by May 21, 2009 requesting to speak at a public hearing,
EPA will hold a public hearing on May 26, 2009. Under the Paperwork
Reduction Act, comments on the information collection provisions are
best assured of having full effect if the Office of Management and
Budget (OMB) receives a copy of your comments on or before June 5,
2009.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-HQ-
OAR-2002-0051, by one of the following methods:
     http://www.regulations.gov: Follow the on-line
instructions for submitting comments.
     E-mail<EMAIL_ADDRESS>     Fax:<PHONE_NUMBER>.
     Mail: U.S. Postal Service, send comments to: EPA Docket
Center (6102T), National Emission Standards for Hazardous Air Pollutant
From the Portland Cement Manufacturing Industry Docket, Docket ID No.
EPA-HQ-OAR-2002-0051, 1200 Pennsylvania Ave., NW., Washington, DC
20460. Please include a total of two copies. In addition, please mail a
copy of your comments on the information collection provisions to the
Office of Information and Regulatory Affairs, Office of Management and
Budget (OMB), Attn: Desk Officer for EPA, 725 17th St., NW.,
Washington, DC 20503.
     Hand Delivery: In person or by courier, deliver comments
to: EPA Docket Center (6102T), Standards of Performance (NSPS) for
Portland Cement Plants Docket, Docket ID No. EPA-HQ-OAR-2007-0877, EPA
West, Room 3334, 1301 Constitution Avenue, NW., Washington, DC 20004.
Such deliveries are only accepted during the Docket's normal hours of
operation, and special arrangements should be made for deliveries of
boxed information. Please include a total of two copies.
    Instructions: Direct your comments to Docket ID No. EPA-HQ-OAR-
2002-0051. EPA's 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 e-mail. The http://www.regulations.gov Web site
is an ``anonymous access'' system, which means EPA will not know your
identity or contact information unless you provide it in the body of
your comment. If you send an e-mail comment directly to EPA without
going through http://www.regulations.gov, your e-mail address will be
automatically captured and included as part of the comment that is
placed in the public docket and made available on the Internet. If you
submit an electronic comment, EPA recommends that you include your name
and other contact information in the body of your comment and with any
disk or CD-ROM you submit. If EPA cannot read your comment due to
technical difficulties and cannot contact you for clarification, EPA
may not be able to consider your comment. Electronic files should avoid
the use of special characters, any form of encryption, and be free of
any defects or viruses.
    Docket: 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,
National Emission Standards for Hazardous Air Pollutants from the
Portland Cement Manufacturing Industry Docket, EPA West, Room 3334,
1301 Constitution Ave., NW., Washington, DC. The Public Reading Room is
open from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding
legal holidays. The telephone number for the Public Reading Room is
(202) 566-1744, and the telephone number for the Docket Center is (202)
566-1742.

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

I. General Information
    A. Does this action apply to me?
    B. What should I consider as I prepare my comments to EPA?
    C. Where can I get a copy of this document?
    D. When would a public hearing occur?
II. Background Information
    A. What is the statutory authority for these proposed
amendments?
    B. Summary of the National Lime Association v. EPA Litigation
    C. EPA's Response to the Remand
    D. Reconsideration of EPA Final Action in Response to the Remand
III. Summary of Proposed Amendments to Subpart LLL
    A. Emissions Limits
    B. Operating Limits
    C. Testing and Monitoring Requirements
IV. Rationale for Proposed Amendments to Subpart LLL
    A. MACT Floor Determination Procedure for all Pollutants

    B. Determination of MACT for Mercury Emissions From Major and
Area Sources
    C. Determination of MACT for THC Emissions From Major and Area
Sources
    D. Determination of MACT for HCl Emissions From Major Sources
    E. Determination of MACT for PM Emissions From Major and Area
Sources
    F. Selection of Compliance Provisions
    G. Selection of Compliance Dates
    H. Discussion of EPA's Sector Based Approach for Cement
Manufacturing
    I. Other Changes and Areas Where We Are Requesting Comment
V. Comments on Notice of Reconsideration and EPA Final Action in
Response To Remand
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 economic impacts?
    J. What are the benefits?
VII. Statutory and Executive Order Reviews
    A. Executive Order 12866: Regulatory Planning and Review
    B. Paperwork Reduction Act
    C. Regulatory Flexibility Act
    D. Unfunded Mandates Reform Act
    E. Executive Order 13132: Federalism
    F. Executive Order 13175: Consultation and Coordination With
Indian Tribal Governments
    G. Executive Order 13045: Protection of Children From
Environmental Health Risks and Safety Risks
    H. Executive Order 13211: Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use
    I. National Technology Transfer Advancement Act
    J. Executive Order 12898: Federal Actions to Address
Environmental Justice in Minority Populations and Low-Income
Populations

I. General Information

A. Does this action apply to me?

    Categories and entities potentially regulated by this proposed rule
include:

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                                           NAICS code
                Category                      \1\                    Examples of regulated entities
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Industry................................       327310  Portland cement plants.
Federal government......................  ...........  Not affected.
State/local/tribal government...........  ...........  Portland cement 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 would be regulated by this
proposed action, you should examine the applicability criteria in 40
CFR 63.1340 (subpart LLL). If you have any questions regarding the
applicability of this proposed action to a particular entity, contact
the person listed in the preceding FOR FURTHER INFORMATION CONTACT
section.

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

    Do not submit information containing CBI to EPA through http://
www.regulations.gov or e-mail. 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, Environmental Protection Agency, Research Triangle Park, NC
27711, Attention Docket ID No. EPA-HQ-OAR-2002-0051. Clearly mark the
part or all of the information that you claim to be CBI. For CBI
information in a disk or CD-ROM that you mail to EPA, mark the outside
of the disk or CD-ROM as CBI and then identify electronically within
the disk or CD-ROM the specific information that is claimed as CBI. In
addition to one complete version of the comment that includes
information claimed as CBI, a copy of the comment that does not contain
the information claimed as CBI must be submitted for inclusion in the
public docket. Information so marked will not be disclosed except in
accordance with procedures set forth in 40 CFR part 2.

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

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

D. When and where would a public hearing occur?

    If anyone contacts EPA requesting to speak at a public hearing by
May 21, 2009, a public hearing will be held on May 26, 2009. To request
a public hearing contact Ms. Pamela Garrett, EPA, Office of Air Quality
Planning and Standards, Sector Policy and Programs Division, Energy
Strategies Group (D243-01), Research Triangle Park, NC 27711, telephone
number<PHONE_NUMBER>, e-mail address<EMAIL_ADDRESS>by the date
specified above in the DATES section. Persons interested in presenting
oral testimony or inquiring as to whether a public hearing is to be
held should also contact Ms. Pamela Garrett at least 2 days in advance
of the potential date of the public hearing.
    If a public hearing is requested, it will be held at 10 a.m. at the
EPA Headquarters, Ariel Rios Building, 12th Street and Pennsylvania
Avenue, Washington, DC 20460 or at a nearby location.

II. Background Information

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

    Section 112(d) of the Clean Air Act (CAA) requires EPA to set
emissions standards for Hazardous Air Pollutants (HAP) emitted by major
stationary sources based on performance of the maximum achievable
control technology (MACT). The MACT standards for existing sources must
be at least as stringent as the average emissions limitation achieved
by the best performing 12 percent of existing sources (for which the
administrator has emissions information) or the best performing 5
sources for source categories with less than 30 sources (CAA section
112(d)(3)(A) and (B)). This level of minimum stringency is called the
MACT floor. For new sources, MACT standards must be at least as
stringent as the control level achieved in practice by the best
controlled similar source (CAA section 112(d)(3)). EPA also must
consider more stringent ``beyond-the-floor'' control options. When
considering beyond-the-floor options, EPA must consider not only the
maximum degree of reduction in

emissions of HAP, but must take into account costs, energy, and nonair
environmental impacts when doing so.
    Section 112(k)(3)(B) of the CAA requires EPA to identify at least
30 HAP that pose the greatest potential health threat in urban areas,
and section 112(c)(3) requires EPA to regulate, under section 112(d)
standards, the area source \1\ categories that represent 90 percent of
the emissions of the 30 ``listed'' HAP (``urban HAP''). We implemented
these listing requirements through the Integrated Urban Air Toxics
Strategy (64 FR 38715, July 19, 1999).\2\
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    \1\ An area source is a stationary source of HAP emissions that
is not a major source. A major source is a stationary source that
emits or has the potential to emit 10 tons per year (tpy) or more of
any HAP or 25 tpy or more of any combination of HAP.
    \2\ \\ Since its publication in the Integrated Urban Air Toxics
Strategy in 1999, EPA has amended the area source category list
several times.
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    The portland cement source category was listed as a source category
for regulation under this 1999 Strategy based on emissions of arsenic,
cadmium, beryllium, lead, and polychlorinated biphenyls. The final
NESHAP for the Portland Cement Manufacturing Industry (64 FR 31898,
June 14, 1999) included emission limits based on performance of MACT
for the control of THC emissions from area sources. This 1999 rule
fulfills the requirement to regulate area source cement kiln emissions
of polychlorinated biphenyls (for which THC is a surrogate). However,
EPA did not include requirements for the control of the non-volatile
metal HAP (arsenic, cadmium, beryllium, and lead) from area sources in
the 1999 rule or in the 2006 amendments. To fulfill our requirements
under section 112(c)(3) and 112(k), EPA is thus proposing to set
emissions standards for these metal HAP from portland cement
manufacturing facilities that are area sources (using particulate
matter as a surrogate). In this proposal, EPA is proposing PM standards
for area sources based on performance of MACT.
    Section 112(c)(6) requires EPA to list, and to regulate under
standards established pursuant to section 112(d)(2) or (d)(4),
categories of sources accounting for not less than 90 percent of
emissions of each of seven specific HAP: alkylated lead compounds;
polycyclic organic matter; hexachlorobenzene; mercury; polychlorinated
byphenyls; 2,3,7,8-tetrachlorodibenzofurans; and 2,3,7,8-
tetrachloroidibenzo-p-dioxin. Standards established under CAA 112(d)(2)
must reflect the performance of MACT. ``Portland cement manufacturing:
non-hazardous waste kilns'' is listed as a source category for
regulation under section 112(d)(2) pursuant to the section 112(c)(6)
requirements due to emissions of polycyclic organic matter, mercury,
and dioxin/furans (63 FR 17838, 17848, April 10, 1998); see also 63 FR
at 14193 (March 24, 1998) (area source cement kilns' emissions of
mercury, dibenzo-p-dioxins and dibenzo-p-furans, polycyclic organic
matter, and polychlorinated biphenyls are subject to MACT).
    Section 129(a)(1)(A) of the Act requires EPA to establish specific
performance standards, including emission limitations, for ``solid
waste incineration units'' generally, and, in particular, for ``solid
waste incineration units combusting commercial or industrial waste''
(section 129(a)(1)(D)).\3\ Section 129 defines ``solid waste
incineration unit'' as ``a distinct operating unit of any facility
which combusts any solid waste material from commercial or industrial
establishments or the general public.'' Section 129(g)(1). Section 129
also provides that ``solid waste'' shall have the meaning established
by EPA pursuant to its authority under the [Resource Conservation and
Recovery Act]. Section 129(g)(6).
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    \3\ CAA section 129 refers to the Solid Waste Disposal Act
(SWDA). However, this act, as amended, is commonly referred to as
the Resource Conservation and Recovery Act (RCRA).
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    In Natural Resources Defense Council v. EPA, 489 F. 3d 1250, 1257-
61 (D.C. Cir. 2007), the court vacated the Commercial and Industrial
Solid Waste Incineration Units (CISWI) Definitions Rule, 70 FR 55568
(Sept. 22, 2005), which EPA issued pursuant to CAA section
129(a)(1)(D). In that rule, EPA defined the term ``commercial or
industrial solid waste incineration unit'' to mean a combustion unit
that combusts ``commercial or industrial waste.'' The rule defined
``commercial or industrial waste'' to mean waste combusted at a unit
that does not recover thermal energy from the combustion for a useful
purpose. Under these definitions, only those units that combusted
commercial or industrial waste and were not designed to, or did not
operate to, recover thermal energy from the combustion would be subject
to section 129 standards. The DC Circuit rejected the definitions
contained in the CISWI Definitions Rule and interpreted the term
``solid waste incineration unit'' in CAA section 129(g)(1) ``to
unambiguously include among the incineration units subject to its
standards any facility that combusts any commercial or industrial solid
waste material at all--subject to the four statutory exceptions
identified in [CAA section 129(g)(1).]'' NRDC v. EPA, 489 F.3d 1250,
1257-58.
    In response to the Court's remand and vacatur of the CISWI
Definitions rule, EPA has initiated a rulemaking to define which
secondary materials are ``solid waste'' for purposes of subtitle D
(non-hazardous waste) of the Resource Conservation and Recovery Act
when burned in a combustion unit. See Advance Notice of Proposed
Rulemaking, 74 FR 41 (January 2, 2009) (soliciting comment on whether
certain secondary materials used as alternative fuels or ingredients
are solid wastes within the meaning of Subtitle D of the Resource
Conservation and Recovery Act). That definition, in turn, would
determine the applicability of section 129(a).
    This definitional rulemaking is relevant to this proceeding because
some portland cement kilns combust secondary materials as alternative
fuels. However, there is no federal regulatory interpretation of
``solid waste'' for EPA to apply under Subtitle D of the Resource
Conservation and Recovery Act, and EPA cannot prejudge the outcome of
that pending rulemaking. Moreover, EPA has imperfect information on the
exact nature of the secondary materials which portland cement kilns
combust, such as information as to the provider(s) of the secondary
materials, how much processing the secondary materials may have
undergone, and other issues potentially relevant in a determination of
whether these materials are to be classified as solid wastes. See 74 FR
at 53-59. EPA therefore cannot reliably determine at this time if the
secondary materials combusted by cement kilns are to be classified as
solid wastes. Accordingly, EPA is basing all determinations as to
source classification on the emissions information now available, as
required by section 112(d)(3), and will necessarily continue to do so
until the solid waste definition discussed above is promulgated. The
current data base classifies all portland cement kilns as section 112
sources (i.e. subject to regulation under section 112). EPA notes,
however, that the combustion of secondary materials as alternative
fuels did not have any appreciable effect on the amount of HAP emitted
by any source.\4\
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    \4\ Development of the MACT Floors for the Proposed NESHAP for
Portland Cement. April 15, 2009.

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

    On June 14, 1999 (64 FR 31898), EPA issued the NESHAP for the
Portland Cement Manufacturing Industry (40 CFR part 63, subpart
LLL).\5\ The 1999 final rule established emission limitations for PM as
a surrogate for non-volatile HAP metals (major sources only), dioxins/
furans, and for greenfield \6\ new sources total THC as a surrogate for
organic HAP. These standards were intended to be based on the
performance of MACT pursuant to sections 112(d)(2) and (3). We did not
establish limits for THC for existing sources and non-greenfield new
sources, nor for HCl or mercury for new or existing sources. We
reasoned that emissions of these constituents were a function of raw
material concentrations and so were essentially uncontrolled, the
result being that there was no level of performance on which a floor
could be based. EPA further found that beyond the floor standards for
these HAP were not warranted.
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    \5\ Cement kilns which burn hazardous waste are a separate
source category, since their emissions of many HAP differ from
portland cement kilns' as a result of the hazardous waste inputs.
Rules for hazardous waste-burning cement kilns are found at subpart
EEE of part 63.
    \6\ For purposes of the 1999 rule a new greenfield kiln is a
kiln constructed after March 24, 1998, at a site where there are no
existing kilns.
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    Ruling on petitions for review of various environmental groups, the
DC Circuit held that EPA had erred in failing to establish section
112(d) standards for mercury, THC (except for greenfield new sources)
and hydrochloric acid. The court held that ``[n]othing in the statute
even suggests that EPA may set emission levels only for those * * *
HAPs controlled with technology.'' National Lime Ass'n v. EPA, 233 F.
3d 625, 633 (DC Cir. 2000). The court also stated that EPA is obligated
to consider other pollution-reducing measures such as process changes
and material substitution. Id. at 634. Later cases go on to hold that
EPA must account for levels of HAP in raw materials and other inputs in
establishing MACT floors, and further hold that sources with low HAP
emission levels due to low levels of HAP in their raw materials can be
considered best performers for purposes of establishing MACT floors.
See, e.g., Sierra Club v. EPA (Brick MACT), 479 F. 3d 875, 882-83 (DC
Cir. 2007).\7\
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    \7\ In the remainder of the opinion, the court in National Lime
Ass'n upheld EPA's standards for particulate matter and dioxin (on
grounds that petitioner had not properly raised arguments in its
opening brief), upheld EPA's use of particulate matter as a
surrogate for HAP metals, and remanded for further explanation EPA's
choice of an analytic method for hydrochloric acid.
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C. EPA's Response to the Remand

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

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

    At the same time we issued the final amendments, EPA on its own
initiative made a determination to reconsider the new source standard
for mercury, the existing and new source standard banning cement kiln
use of certain mercury-containing fly ash, and the new source standard
for THC (71 FR 76553, December 20, 2006). EPA granted reconsideration
of the new source mercury standard both due to substantive issues
relating to the performance of wet scrubbers and because information
about their performance in the industry had not been available for
public comment at the time of proposal but is now available in the
docket. We also committed to undertake a test program for mercury
emissions from cement kilns equipped with wet scrubbers that would
enable us to resolve these issues. We further explained that we were
granting reconsideration of the work practice requirement banning the
use of certain mercury-containing fly ash in cement kilns to allow
further opportunity for comment on both the standard and the underlying
rationale and because we did not feel we had the level of analysis we
would like to support a beyond-the-floor determination. We granted
reconsideration of the new source standard for THC because the
information on which the standard was based arose after the period for
public comment. We requested comment on the actual standard, whether
the standard is appropriate for reconstructed new sources (if any
should occur) and the information on which the standard is based. We
specifically solicited data on THC emission levels from preheater/
precalciner cement kilns. We stated that we would evaluate all data and
comments received, and determine whether in light of those data and
comments it is appropriate to amend the promulgated standards.
    EPA received comments on the notice of reconsideration from two
cement companies, three energy companies, three industry associations,
a technical consultant, one State, one environmental group, one ash
management company, one fuels company, and one private citizen. As part
of these comments, one industry trade association submitted a petition
to withdraw the new source MACT standards for mercury and THC and one
environmental group submitted a petition for reconsideration of the
2006 final action. A summary of these comments is available in the
docket for this rulemaking.\8\
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    \8\ Summary of Comments on December 20, 2006 Final Rule and
Notice of Reconsideration. April 15, 2009.
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    In addition to the reconsideration discussed above, EPA received a
petition from Sierra Club requesting reconsideration of the existing
source standards for THC, mercury, and HCl, and judicial petitions for
review challenging the final amendments. EPA granted the
reconsideration petition. The judicial petitions have been

combined and are being held in abeyance pending the results of the
reconsideration.
    In March 2007 the DC Circuit court issued an opinion (Sierra Club
v. EPA, 479 F. 3d 875 (DC Cir. 2007) (Brick MACT)) vacating and
remanding section 112(d) MACT standards for the Brick and Structural
Clay Ceramics source categories. Some key holdings in that case were:
     Floors for existing sources must reflect the average
emission limitation achieved by the best-performing 12 percent of
existing sources, not levels EPA considers to be achievable by all
sources (479 F. 3d at 880-81);
     EPA cannot set floors of ``no control.'' The Court
reiterated its prior holdings, including National Lime Ass'n,
confirming that EPA must set floor standards for all HAP emitted by the
major source, including those HAP that are not controlled by at-the-
stack control devices (479 F. 3d at 883);
     EPA cannot ignore non-technology factors that reduce HAP
emissions. Specifically, the Court held that ``EPA's decision to base
floors exclusively on technology even though non-technology factors
affect emissions violates the Act.'' (479 F. 3d at 883)

    Based on the Brick MACT decision, we believe a source's performance
resulting from the presence or absence of HAP in raw materials must be
accounted for in establishing floors; i.e., a low emitter due to low
HAP proprietary raw materials can still be a best performer. In
addition, the fact that a specific level of performance is unintended
is not a legal basis for excluding the source's performance from
consideration. National Lime Ass'n, 233 F. 3d at 640.
    The Brick MACT decision also stated that EPA may account for
variability in setting floors. However, the court found that EPA erred
in assessing variability because it relied on data from the worst
performers to estimate best performers' variability, and held that
``EPA may not use emission levels of the worst performers to estimate
variability of the best performers without a demonstrated relationship
between the two.'' 479 F. 3d at 882.
    The majority opinion in the Brick MACT case does not address the
possibility of subcategorization to address differences in the HAP
content of raw materials. However, in his concurring opinion Judge
Williams stated that EPA's ability to create subcategories for sources
of different classes, size, or type (section 112 (d)(1)) may provide a
means out of the situation where the floor standards are achieved for
some sources, but the same floors cannot be achieved for other sources
due to differences in local raw materials whose use is essential. Id.
at 884-85.\9\
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    \9\ ``What if meeting the `floors' is extremely or even
prohibitively costly for particular plants because of conditions
specific to those plants (e.g., adoption of the necessary technology
requires very costly retrofitting, or the required technology
cannot, given local inputs whose use is essential, achieve the
`floor')? For these plants, it would seem that what has been
`achieved' under Sec.  112(d)(3) would not be `achievable' under
Sec.  112(d)(2) in light of the latter's mandate to EPA to consider
cost. * * * [O]ne legitimate basis for creating additional
subcategories must be the interest in keeping the relation between
`achieved' and `achievable' in accord with common sense and the
reasonable meaning of the statute. '' Id. at 884-85
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    After considering the implications of this decision, EPA granted
the petition for reconsideration of all the existing source standards
in the 2006 rulemaking.
    A second court opinion is also relevant to this proposal. In Sierra
Club v. EPA, 551 F. 3d 1019 (DC Cir. 2008) the court vacated the
regulations contained in the General Provisions which exempt major
sources from MACT standards during periods of startup, shutdown and
malfunction (SSM)). The regulations (in 40 CFR 63.6(f)(1) and
63.6(h)(1)) provided that sources need not comply with the relevant
section 112(d) standard during SSM events and instead must ``minimize
emissions * * * to the greatest extent which is consistent with safety
and good air pollution control practices.'' The current Portland Cement
NESHAP does not contain specific provisions covering operation during
SSM operating modes; rather it references the now-vacated rules in the
General Provisions. As a result of the court decision, we are
addressing them in this rulemaking. Discussion of this issue may be
found in Section IV.G.

III. Summary of Proposed Amendments to Subpart LLL

    This section presents the proposed amendments to the Portland
Cement NESHAP. In the section presenting the amended rule language,
there is some language that it not amendatory, but is presented for the
reader's convenience. We are not reopening or otherwise considering
unchanged rule language presented for the reader's convenience, and
will not accept comments on such language.

A. Emissions Limits

    We are proposing the following new emission limits in this action
categorized below by their sources in a typical Portland cement
production process.
Kilns and In-line Kiln/Raw Mills
    Mercury. For cement kilns or in-line kilns/raw mills an emissions
limit of 43 lb/million(MM) tons clinker for existing sources and 14 lb/
MM tons clinker for new sources. Both proposed limits are based on a 30
day rolling average.
    THC. For cement kilns or in-line kilns/raw mills an emissions limit
of 7 parts per million by volume (ppmv) for existing sources and 6 ppmv
for new sources, measured dry as propane and corrected to 7 percent
oxygen, measured on a 30 rolling day average in each case. Because the
proposed existing source standard would be more stringent than the new
source standard of 50 ppmv contained in the 1999 final rule for
greenfield new sources, we are also proposing to remove the 50 ppmv
standard.
    As an alternative to the THC standard, we are proposing that the
cement kilns or in-line kilns/raw mills can meet a standard of 2 ppmv
total combined organic HAP for existing sources or 1 ppmv total organic
HAP combined for new sources, measured dry and corrected to 7 percent
oxygen. We believe this standard is equivalent to the proposed THC
standard as discussed in section IV.C. The alternative standard would
be based on organic HAP emission testing and concurrent THC CEMS
measurements that would establish a site specific THC limit that would
demonstrate compliance with the total organic HAP limit. The site
specific THC limit would be measured as a 30 day rolling average.
    PM. For cement kilns or cement kilns/in-line raw mills an emissions
limit of 0.085 pounds per ton (lb/ton) clinker for existing sources and
0.080 lb/tons clinker for new sources. Kilns and kiln/in-line raw mills
where the clinker cooler gas is combined with the kiln exhaust and sent
to a single control device for energy efficiency purposes (i.e., to
extract heat from the clinker cooler exhaust) would be allowed to
adjust the PM standard to an equivalent level accounting for the
increased gas flow due to combining of kiln and clinker cooler exhaust.
    Opacity. We are proposing to remove all opacity standards for kilns
and clinker coolers because these sources will be required to monitor
compliance with the PM emissions limits by more accurate means.
    Hydrochloric Acid. For cement kilns or cement kilns/in-line raw
mills an emissions limit of 2 ppmv for existing sources and 0.1 ppmv
for new sources, measured dry and corrected to 7 percent oxygen. For
facilities that are required to use a continuous emissions monitoring

system (CEMS), compliance would be based on a 30 day rolling average.
Clinker Coolers
    For clinker coolers a PM emissions limit of 0.085 lb/ton clinker
for existing sources and 0.080 lb/tons clinker for new sources.
Raw Material Dryers
    THC. For raw materials dryers an emissions limit of 7 ppmv for
existing sources and 6 ppmv for new sources, measured dry as propane
and corrected to 7 percent oxygen, measured on a 30 day rolling
average. Because the proposed existing source standard would be more
stringent than the new source standard of 50 ppmv contained in the 1999
final rule for Greenfield new sources, we are also proposing to remove
the 50 ppmv standard.
    As an alternative to the THC standard, the raw material dryer can
meet a standard of 2 ppmv total combined organic HAP for existing
sources or 1 ppmv total organic HAP combined for new sources, measured
dry and corrected to 7 percent oxygen. The alternative standard would
be based on organic HAP emission testing and concurrent THC CEMS
measurements that would establish a site specific THC limit that would
demonstrate compliance with the total organic HAP limit. The site
specific THC limit would be measured as a 30 day rolling average.

B. Operating Limits

    EPA is proposing to eliminate the restriction on the use of fly ash
where the mercury content of the fly ash has been increased through the
use of activated carbon. Given the proposed emission limitation for
mercury, whereby kilns or cement kilns/in-line raw mills must
continuously meet the mercury emission limits described above
(including when using these materials) there does not appear to be a
need for such a provision. For the same reason, EPA is proposing to
remove the requirement to maintain the amount of cement kiln dust
wasted during testing of a control device, and the provision requiring
that kilns remove from the kiln system sufficient amounts of dust so as
not to impair product quality.

C. Testing and Monitoring Requirements

    We are proposing the following changes in testing and monitoring
requirements:
    Kilns and kiln/in-line raw mills would be required to meet the
following changed monitoring/testing requirements:
     CEMS (PS-12A) or sorbent trap monitors (PS-12B) to
continuously measure mercury emissions, along with Procedure 5 for
ongoing quality assurance.
     CEMS meeting the requirement of PS-8A to measure THC
emissions for existing sources (new sources are already required to
monitor THC with a CEM). Kilns and kiln/in-line raw mills meeting the
organic HAP alternative to the THC limit would still be required to
continuously monitor THC (based on the results of THC monitoring done
concurrently with the Method 320 test), and would also be required to
test emissions using EPA Method 320 or ASTM D6348-03 every five years
to identify the organic HAP component of their THC emissions.
     Installation and operation of a bag leak detection system
to demonstrate compliance with the PM emissions limit. If electrostatic
precipitators (ESP) are used for PM control an ESP predictive model to
monitor the performance of ESP controlling PM emissions from kilns
would be required. As an alternative EPA is proposing that sources may
use a PM CEMS that meets the requirements of PS-11. Though we are
proposing the PM CEMS as an alternative compliance method, we are
taking comment on requiring PM CEMS to demonstrate compliance.
     CEMS meeting the requirements of PS-15 would be required
to demonstrate compliance with the HCl standard. If a facility is using
a caustic scrubber to meet the standard, EPA Test Method 321 and
ongoing continuous parameter monitoring of the scrubber may be used in
lieu of a CEMS to demonstrate compliance. The M321 test must be
repeated every 5 years.
    For clinker coolers, EPA is proposing use of a bag leak detection
system to demonstrate compliance with the proposed PM emissions limit.
If an ESP is used for PM control on clinker coolers, an ESP predictive
model to monitor the performance of ESP controlling PM emissions from
kilns would be required. As an alternative, EPA is proposing that a PM
CEMS that meets the requirements of PS-11 may be used.
    Raw material dryers that are existing sources would be required to
install and operate CEMS meeting the requirement of PS-8A to measure
THC emissions. (New sources are already required to monitor THC with a
CEM). Raw material dryers meeting the organic HAP alternative to the
THC limit would still be required to continuously monitor THC (based on
the results of THC monitoring done concurrently with the Method 320
test), and would also be required to test emissions using EPA Method
320 or ASTM D6348-03 every five years to identify the organic HAP
component of their THC emissions.
    New or reconstructed raw material dryers and raw or finish mills
would be subject to longer Method 22 and, potentially, to longer Method
9 tests. The increase in test length duration is necessary to better
reflect the operating characteristics of sources subject to the
proposed rule.

IV. Rationale for Proposed Amendments to Subpart LLL

A. MACT Floor Determination Procedure for all Pollutants

    The MACT floor limits for each of the HAP and HAP surrogates
(mercury, total hydrocarbons, HCl, and particulate matter) are
calculated based on the performance of the lowest emitting (best
performing) sources in each of the MACT pool sources. We ranked all of
the sources for which we had data based on their emissions and
identified the lowest emitting 12 percent of the sources for which we
had data, which ranged from two kilns for THC to 11 kilns for mercury
for existing sources. For new source MACT, the floor was based on the
best performing source. The MACT floor limit is calculated from a
formula that is a modified prediction limit, designed to estimate a
MACT floor level that is achievable by the average of the best
performing sources (i.e., those in the MACT pool) if the best
performing sources were able to replicate the compliance tests in our
data base. Specifically, the MACT floor limit is an upper prediction
limit (UPL) calculated from: \10\
---------------------------------------------------------------------------

    \10\ More details on the calculation of the MACT floor limits
are given in the memorandum Development of The MACT Floors For The
Proposed NESHAP for Portland Cement. April 15, 2009.

---------------------------------------------------------------------------
UPL = xp + t * (VT)\0.5\

Where:

Xp = average of the best performing MACT pool sources,
t = Student's t-factor evaluated at 99 percent confidence, and
vT = total variance determined as the sum of the within-
source variance and the between-source variance.

The between-source variance is the variance of the average of the best
performing source averages. The within-source variance is the variance
of the MACT source average considering ``m'' number of future
individual test runs used to make up the average to determine
compliance. The value of ``m'' is used to reduce the variability to
account for the lower variability when averaging of individual runs is
used to determine compliance in the future. For example, if 30-day
averages are used to

determine compliance (m=30), the variability based 30-day average is
much lower than the variability of the daily measurements in the data
base, which results in a lower UPL for the 30-day average.

B. Determination of MACT for Mercury Emissions From Major and Area
Sources

    The limits for existing and new sources we are proposing here apply
to both area and major new sources. These limits would also apply to
area sources consistent with section 112(c)(6) of the Act, as EPA
determined in the original rule. See 63 FR at 14193.
1. Floor Determination
Selection of Existing Source Floor
    Cement kilns' emissions of mercury reflect exclusively the amounts
of mercury in each kiln's feedstock and fuel inputs. The amounts of
mercury in these inputs and their relative contributions to overall
mercury kiln emissions vary by site. In many cases the majority of the
mercury emissions result from the mercury present as a trace
contaminant in the limestone, which typically comes from a proprietary
quarry located adjacent to the plant. Limestone is the single largest
input, by mass, to a cement kiln's total mass input, typically making
up 80 percent of that loading. Mercury is also found as a trace
contaminant in the other inputs to the kiln such as the additives that
supply the required silica, alumina, and iron. Mercury is also present
in the coal and petroleum coke typically used to fuel cement kilns.
    Based on our current information, mercury levels in limestone can
vary significantly, both within a single quarry and between quarries.
Since quarries are generally proprietary, this variability is inherent
and site-specific. Mercury levels in additives and fuels likewise vary
significantly, although mercury emissions attributable to limestone
often dominate the total due to the larger amount of mass input
contributed by limestone (see further discussion of this issue at Other
Options EPA considered in Setting Floor for Mercury below).
    The first step in establishing a MACT standard is to determine the
MACT floor. A necessary step in doing so is determining the amount of
HAP emitted. In the case of mercury emitted by cement kilns, this is
not necessarily a straightforward undertaking. Single stack
measurements represent a snapshot in time of a source's emissions,
always raising questions of how representative such emissions are of
the source's emissions over time. This problem is compounded in the
case of cement kilns, because cement kilns do not emit mercury
uniformly. Our current data suggest that, for all kilns, the mercury
content of the feed and fuels varies significantly from day-to-day.
Because most cement kilns have no mercury emissions control, the
variations in mercury inputs directly translate to a variability of
mercury stack emissions. For modern preheater and preheater/precalciner
kilns this problem is compounded because these kilns have in-line raw
mills. With in-line raw mills, mercury is captured in the ground raw
meal in the in-line raw mill and this raw meal (containing mercury) is
returned as feed to the kiln. Mercury emissions may remain low during
such recycling operations. However, as part of normal kiln operation
raw mills must be periodically shut down for maintenance, and mercury-
containing exhaust gases from the kiln are then bypassed directly to
the main air pollution control device resulting in significantly
increased mercury emissions at the stack. The result is that at any
given time, mercury emissions from such cement kilns are either low or
high, but rarely in equilibrium, so that single stack tests are likely
to either underestimate or overestimate cement kilns' performance over
time. Put another way, we believe that single short term stack test
data (typically a few hours) are probably not indicative of long term
emissions performance, and so are not the best indicator of performance
over time. With these facts in mind, we carefully considered
alternatives other than use of single short-term stack test results to
quantify kilns' performance for mercury.
    An alternative to short term stack test data would be to use
mercury continuous monitoring data over a longer time period. Because
no cement kilns in the United States have continuous mercury monitors,
this option was not available. However, mercury is an element.
Therefore, all the mercury that enters a kiln has to leave the kiln in
some fashion. The available data indicate that almost no mercury leaves
the kiln as part of the clinker (product). Therefore, our methodology
assumes over the long term that all the mercury leaves the kiln as a
stack emission with three exceptions:
    1. If instead of returning all particulate captured in the
particulate control device to the kiln, the source instead removes some
of it from the circuit entirely, i.e., the kiln does not reuse all
(wastes some) cement kiln dust (CKD); or
    2. The kiln is equipped with an alkali bypass, which means all CKD
captured in the alkali bypass PM control is wasted, and/or;
    3. If the kiln has a wet scrubber (usually for SO2
control), the scrubber will remove some mercury which our methodology
assumes will end up in the gypsum generated by the scrubber.
    Based on these facts we decided that the most accurate method
available to us to determine long term mercury emissions performance
was to do a total mass balance. We did so by obtaining data on all the
kiln mercury inputs (i.e., all raw materials and all fuels) for a large
group of kilns, and assuming all mercury that enters the kiln is
emitted except for the three conditions noted above. Pursuant to
letters mandating data gathering, issued under the authority of section
114, we obtained 30 days of daily data on kiln mercury concentrations
in each individual raw material, fuel, and CKD for 89 kilns (which
represent 59 percent of total kilns), along with annual mass inputs and
the amount of material collected in the PM control device (or alkali PM
control device) that is wasted rather than returned to the kiln.
    These data were submitted to EPA as daily concentrations for the
inputs, i.e., samples of all inputs were taken daily and analyzed daily
for their mercury content. We took the daily averages, calculated a
mean concentration, and multiplied the mean concentration by annual
materials use to calculate an annual mercury emission for each of the
89 kilns. If the facility wasted CKD, we subtracted out the annual
mercury that left the system in the CKD. If the facility had a wet
scrubber (the only control device currently in use among the sampled
kilns with any substantial mercury capture efficiency), we subtracted
out the annual mercury attributable to use of the scrubber. There are
five cement kilns using wet scrubbers and EPA has removal efficiencies
for four of these kilns (based on inlet/outlet testing conducted at
EPA's request concurrent with the input sampling). We attributed a
removal efficiency for the fifth kiln based on the average removal
efficiency of the other four kilns.
    We acknowledge that an additional source of uncertainty in the mass
balance methodology for estimating the capture efficiencies of wet
scrubbers is the variability in the mercury speciation ratios
(elemental to divalent). These ratios, which are dependent on the
amount of chlorine present and other factors, would be expected to vary
at different kilns. Only the soluble divalent mercury fraction will be

captured by a wet scrubber. We note, however, that mercury speciation
would be expected to have little effect on mercury emissions in the
case where wet scrubbers, or other add-on controls such as activated
carbon injection (ACI), are not used, because for most facilities,
mercury captured in the PM controls is returned to the kiln. In cases
where some of the collected PM is wasted, we had 30 days of actual
mercury content data for wasted material.
    For each kiln, we calculated an average annual emission factor,
which is the average projected emission rate for each kiln. We did this
by dividing calculated annual emissions by total inputs. We then ranked
each kiln from lowest average emission factor to highest. The resulting
emissions factors for 87 of the 89 ranged (relatively continuously)
from 7 to 300 pounds of mercury per million tons of feed. Two kilns
showed considerably higher numbers, approximately 1200 and 2000 pounds
per ton of feed. These two facilities have atypically high mercury
contents in the limestone in their proprietary quarries which are the
most significant contributors to the high mercury emissions.
    Based on these data and ranking methodology, the existing source
MACT floor would be the average of the lowest emitting 12 percent of
the kilns for which we have data, which would be the 11 kilns with
lowest emissions (as calculated), shown in Table 1.

                       Table 1--Mercury MACT Floor
------------------------------------------------------------------------
                                                       Mercury emissions
                      Kiln code                        (lb/MM ton feed)
------------------------------------------------------------------------
1233................................................                7.14
1650................................................               10.83
1589................................................               11.11
1302................................................               14.51
1259................................................               15.16
1315................................................               15.41
1248................................................               18.09
1286................................................               21.12
1435................................................               22.89
1484................................................               22.89
1364................................................               23.92
------------------------------------------------------------------------
                          MACT--Existing kilns
------------------------------------------------------------------------
Average: lb/MM tons feed (lb/MM tons clinker).......         16.6 (27.4)
Variability (t*vT\0.5\).............................                9.52
99th percentile: lb/MM tons feed (lb/MM tons                     26 (43)
 clinker)...........................................
------------------------------------------------------------------------
                             MACT--New kilns
------------------------------------------------------------------------
Average: lb/MM tons feed (lb/MM tons clinker).......          7.1 (11.8)
Variability (t*vT\0.5\).............................                 1.3
99th percentile: lb/MM tons feed (lb/MM tons                    8.4 (14)
 clinker)...........................................
------------------------------------------------------------------------

    The average emission rate for these kilns is 16.6 pounds per
million tons (lb/MM) tons feed (27.4 lb/MM tons clinker). The emission
rate of the single lowest emitting source is 7.1 lb/MM tons feed (11.8
lb/MM tons clinker).
    As previously discussed above, we account for variability in
setting floors, not only because variability is an element of
performance, but because it is reasonable to assess best performance
over time. Here, for example, we know that the 11 lowest emitting kiln
emission estimates are averages, and that the actual emissions will
vary over time. If we do not account for this variability, we would
expect that even the kilns that perform better than the floor on
average would potentially exceed the floor emission levels a
significant part of the time--meaning that their performance was
assessed incorrectly in the first instance.
    For the 11 lowest emitting kilns, we calculated a daily emission
rate using the daily concentration values and annual materials inputs
divided by each kiln's operating days.\11\ The results are shown in
Table 1 and represent the average performance of each kiln over the 30-
day period. We then calculated the average performance of the 11 lowest
emitting kilns (17 lb/MM tons of feed) and the variances of the daily
emission rates for each kiln which is a direct measure of the
variability of the data set. This variability includes the day-to-day
variability in the total mercury input to each kiln and variability of
the sampling and analysis methods over the 30-day period, and it
includes the variability resulting from site-to-site differences for
the 11 lowest emitters. We calculated the MACT floor (26 lb/MM tons
feed) based on the UPL (upper 99th percentile) as described earlier
from the average performance of the 11 lowest emitting kilns, Students
t-factor, and the total variability, which was adjusted to account for
the lower variability when using 30 day averages.
---------------------------------------------------------------------------

    \11\ In the daily calculations, we treated the CKD removal as if
it was a control device, and applied the overall percent reduction
rather that using the daily CKD concentration value. We used this
approach because if we used daily CKD removal values, some days
showed negative mercury emissions rates. This is because of the
mercury recycling issues discussed above.
---------------------------------------------------------------------------

    EPA also has some information which tends to corroborate the
variability factor used to calculate the floor for mercury. These data
are not emissions data; they are data on the total mercury content of
feed materials over periods of 12 months or longer. Because mercury
emissions correlate with mercury content of feed materials, we believe
an analysis of the variability of the feed materials is an accurate
surrogate for the variability of mercury emissions over time. These
long term data are from multiple kilns from a single company that are
not ranked among the lowest emitters, but are nonetheless germane as a
crosscheck on variability of mercury content of feed materials
(including whether 30 days of sampling, coupled with statistically
derived variability of that data set and a 99th percentile, adequately
measures that variability).
    One way of comparing the variability among different data sets with
different average values is to calculate and compare the relative
standard deviations (RSD), which is the standard deviation divided by
the mean, of each set. If the RSD are comparable, then one can conclude
that the variability among the data sets is comparable. The results of
such an analysis are given in Table 2 below. The long term data
represent long term averages of feed material mercury content based on
12 months of data or more, whereas the MACT data sets are for 30
consecutive days of data. The RSD of the long term data range from 0.29
to 1.05, and the RSD of the MACT floor kilns range from 0.10 to 0.89.
This comparison suggests that our method of calculating variability in
the proposed floor based on variances/99th percentile UPL appears to
adequately encompass sources' long-term variability.

     Table 2--Comparison of Long-Term Kiln Feed Mercury Concentration at Essroc Plants With the Feed Mercury
                                   Concentration Data for the MACT Floor Kilns
----------------------------------------------------------------------------------------------------------------
                                           PPM Hg in feed
                                     --------------------------
                Kiln                                 Standard       RSD                     Source
                                          Mean      deviation
----------------------------------------------------------------------------------------------------------------
1248 \a\............................        0.021        0.002         0.10  MACT floor kiln.\b\
1589 \a\............................        0.021        0.002         0.10  MACT floor kiln.
1435................................        0.012        0.002         0.16  MACT floor kiln.
1484................................        0.012        0.002         0.16  MACT floor kiln.
1233................................        0.011        0.002         0.16  MACT floor kiln.
1650................................        0.025        0.005         0.22  MACT floor kiln.
Speed...............................        0.055        0.016         0.29  Essroc.\c\
1286................................        0.006        0.002         0.32  MACT floor kiln.
1364................................        0.006        0.002         0.32  MACT floor kiln.
San Juan............................        0.322        0.108         0.34  Essroc.
Bessemer............................        0.021        0.007         0.35  Essroc.
Logansport..........................        0.022        0.008         0.37  Essroc.
Naz III.............................        0.016        0.010         0.61  Essroc.
Naz I...............................        2.974        1.838         0.62  Essroc.
1302................................        0.006        0.004         0.68  MACT floor kiln.
1315................................        0.006        0.004         0.68  MACT floor kiln.
Martinsburg.........................        0.023        0.017         0.89  Essroc.
1259................................        0.008        0.007         0.89  MACT floor kiln.
Picton..............................        0.075        0.078         1.05  Essroc.
----------------------------------------------------------------------------------------------------------------
\a\ Same feed sample applied to multiple kilns at the plant.
\b\ MACT floor kilns' variabilities are all based on approximately 30 days of data.
\c\ Essroc kiln's variabilities are all based on 12 months to three years of data.

    We are proposing to express the floor as a 30-day rolling average
for the following two reasons. First, as explained earlier, daily
variations in mercury emissions at the stack for all kilns with in-line
raw mills is greater than daily variability of mercury levels in
inputs. This is because mercury is emitted in high concentrations
during mill-off conditions, but in lower concentrations when mercury is
recycled to the kiln via the raw mill (`mill-on'). We believe that 30
days is the minimum averaging time that allows for this mill-on/mill-
off variation.
    Second, a 30-day rolling average is tied to our proposed
implementation regime, which in turn is based on the means by which the
data used to generate the standard were developed. As explained above,
the proposed floor reflects 30 days of sampling which are averaged,
corresponding to the proposed 30-day averaging period. EPA is also
proposing to monitor compliance by means of daily monitoring via a
CEMS, so that the proposed implementation regime likewise mirrors the
means by which the underlying data were gathered and used in developing
the standard.
    Critical to this variability calculation is the assumption that EPA
is adequately accounting for variable mercury content in kiln
inputs.\12\ As noted, we did so based on 30 days of continuous sampling
of all kiln inputs, plus use of a further statistical variability
factor (based on that data set) and use of the 99th percentile UPL. The
30-day averaging time in the standard is a further means of accounting
for variability, and accords with the data and methodology EPA used to
develop the floor level.
---------------------------------------------------------------------------

    \12\ Since only five kilns have stack control devices,
variability of performance of these controls (wet scrubbers),
although important, plays a less critical role in this analysis.
---------------------------------------------------------------------------

    We solicit comment on the accuracy and appropriateness of this
analysis. The most pertinent information would of course be additional
data of raw material and fuel mercury contents and usage to specific
kilns (especially data from sampling over a longer period than 30
days).\13\ EPA also expressly solicits further information regarding
potential substitutability of non-limestone kiln inputs and whether
kilns actually utilize inputs other than those reflected in the 30-day
sampling effort comprising EPA's present data base for mercury, and if
so, what mercury levels are in these inputs.
---------------------------------------------------------------------------

    \13\ Some advance commenters have posited a larger variability
factor to reflect the historic known variation in mercury content in
limestone and other inputs, as reflected in various geological
surveys. However, at issue is not variability for the source
category as a whole, but specific sources' variability. So any
resort to information not coming directly from a best performer's
own operating history must be accompanied by an explanation of its
relevance for best performer's variability in order to be considered
relevant. See Brick MACT, 479 F. 3d at 881-82.
---------------------------------------------------------------------------

Selection of New Source Floor
    Based on Table 1, the average associated with the single lowest
emitting kiln is 7 lb/MM tons feed (12 lb/MM tons clinker). Applying
the UPL formula discussed earlier based on the daily emissions for the
best performing kiln, we calculated its 99th percentile UPL of
performance, which results in a new source MACT level of 8.4 lb/MM tons
feed (14 lb/MM tons clinker).
    Because this new source floor is expressed on a different basis
than the standard EPA promulgated in December 2006, which was a 41
[micro]g/dscm not to be exceeded standard, it is difficult to directly
compare the new source floor proposed in this action to the December
2006 standard. The December 2006 new source mercury emissions limit was
based on the performance of wet scrubber-equipped cement kilns. In our
current analysis these wet scrubber-equipped kilns were among the
lowest emitting kilns, but not the lowest emitting kiln used to
establish this proposed new source limit. Based on this fact, we
believe this proposed new source floor (and standard, since EPA is not
proposing a beyond-the-floor standard) is approximately 30 percent
lower than the December 2006 standard.
Other Options EPA Considered in Setting Floors for Mercury
    EPA may create subcategories which distinguish among ``classes,
types, and sizes of sources''. Section 112(d)(1). EPA has carefully
considered that possibility

in considering potential standards for mercury emitted by portland
cement kilns. Were EPA to do so, each subcategory would have its own
floor and standard, reflecting performance of the sources within that
subcategory. EPA may create a subcategory applicable to a single HAP,
rather than to all HAP emitted by the source category, if the facts
warrant (so that, for example, a subcategory for kilns emitting
mercury, but a single category for kilns emitting HCl, is legally
permissible with a proper factual basis). Normally, any basis for
subcategorizing must be related to an effect on emissions, rather than
to some difference among sources which does not affect emissions
performance.
    The subcategorization possibilities for mercury which we considered
are the type of kiln, presence of an inline raw mill, practice of
wasting cement kiln dust, mercury concentration of limestone in the
kiln's proprietary quarry, or geographic location. Mercury emissions
are not affected by kiln type (i.e., wet or dry, pre-calcining or not)
because none of these distinctions have a bearing on the amount of
mercury inputted to the kiln or emitted by it. In contrast, the
presence of an in-line raw mill affects mercury emissions in the short
term because the in-line raw mill tends to collect mercury in the
exhaust gas and transfer it to the kiln feed. However, since (as
discussed above) the raw mill must be shut down periodically for
maintenance while the kiln continues to operate, all or most of the
collected mercury simply gets emitted during the raw mill shutdown and
total mercury emissions over time are not changed.
    The practice of wasting cement kiln dust does affect emissions.
This practice means that a portion of the material collected on the PM
control device is removed from the kiln system, rather than recycled to
the kiln. Some of the mercury condenses on the PM collected on the PM
control device, so wasting CKD also removes some mercury from the kiln
system (and therefore it is not emitted). However, since this practice
could be considered to ``control'' mercury, subcategorization by CKD
wasting would be the same as subcategorizing by control device, which
is not permissible. See 69 FR at 403 (Jan. 5, 2004).
    There is no variation in kiln location (i.e., geographical
distinction) which would justify subcategorization. We examined the
geographical distribution of mercury emissions and total mercury and
found no correlation. For example, no one region of the country has
kilns that tend to be all low- or high-emitting kilns.
    We also rejected subcategorization by total mercury inputs.
Subcategorization by this method would inevitability result in a
situation where kilns with higher total mercury inputs would have
higher emission limits. Total mercury inputs are correlated with
mercury emissions. So a facility that currently has lower mercury
inputs could potentially simply substitute a higher mercury raw
material without any requirement to control the additional mercury. In
addition, fuels and other additives are non-captive \14\ situations,
and thus do not readily differentiate kilns by ``size, class, or
type''. Finally, because of the direct correlation of mercury emissions
and mercury inputs, subcategorization by total mercury inputs could
potentially be viewed as a similar situation to subcategorization by
control device.
---------------------------------------------------------------------------

    \14\ `Non-captive' means these materials do not necessarily come
from the facility's proprietary quarry and the facility has choices
for the source of these materials.
---------------------------------------------------------------------------

    The subcategorization option that we believe is most pertinent
would be to subcategorize by the facility's proprietary limestone
quarry. All cement plans have a limestone quarry located adjacent to or
very close to the cement plant. This quarry supplies limestone only to
its associated plant, and is not accessible to other plants. Typically
quarries are developed to provide 50 to 100 years of limestone, and the
cement kiln is located based on the location of the quarry. See 70 FR
at 72333. For this reason, we believe that a facility's proprietary
quarry is an inherent part of the process such that the kiln and the
quarry together can be viewed as the affected source. Also, the amount
of mercury in the proprietary quarry can significantly affect mercury
emission because (as noted above) limestone makes up about 80 percent
of the total inputs to the kiln. Thus, kilns with mercury above a given
level might be considered a different type or class of kiln because
their process necessarily requires the use of that higher-mercury
input.
    The facts, however, do not obviously indicate sharp disparities in
limestone mercury content that readily differentiate among types of
sources. Figure 1 presents the average mercury contents of the
proprietary quarries on the 89 kilns in EPA's present data base.

[GRAPHIC] [TIFF OMITTED] TP06MY09.052

    These data, as we presently evaluate them, do not readily support a
subcategorization approach--putting aside for the moment the high
mercury limestone kilns (at the far right of the distribution tail in
Figure 1) which are discussed separately. As shown in Figure 1, mercury
levels in limestone are more of a continuum with no immediately evident
breakpoints (again, putting aside the high-mercury limestone kilns).
More important, kilns with quarries with varied mercury content can and
do have similar mercury emissions, and in many instances, limestone
mercury is not the dominant source of mercury in the kilns' emissions
notwithstanding that limestone is the principal volumetric input. Thus
for about 55 percent of the kilns (49 of 89), non-limestone mercury
accounted for greater than 50 percent of the kiln's mercury
emissions.\15\ For nearly 70 percent of the kilns (62 of 89), limestone
mercury accounted for at least one-third of total mercury emissions.
---------------------------------------------------------------------------

    \15\ In certain instances, percentages of non-limestone mercury
are high because limestone mercury content was low. However, in many
instances, non-limestone mercury contributions exceeded those from
limestone even where limestone mercury contribution was relatively
high. See Table 3.

                          Table 3--Origins of Mercury in Portland Cement Manufacturing
                                        [Sorted by limestone percent] \a\
----------------------------------------------------------------------------------------------------------------
                                                     Limestone
                                                      mercury       Percent Hg      Percent Hg      Percent Hg
             Random number kiln code               concentration  from limestone  from other raw    from fuels
                                                       (ppb)            \a\          materials
----------------------------------------------------------------------------------------------------------------
1629............................................          652.92              92               8               0
1647............................................           40.88              89               5               7
1581............................................           96.73              88               9               3
1376............................................           27.43              87               5               8
1609............................................         1120.75              87              13               0
1688............................................           27.43              87               5               8
1690............................................           27.43              87               5               8
1339............................................           21.00              84               8               9
1324............................................           21.30              83               1              16
1693............................................           21.72              80               7              13
1692............................................           20.23              79              13               8
1419............................................           20.92              77              16               8
1248............................................           20.92              76              17               6
1302............................................            6.24              76               7              17
1686............................................           51.21              76              19               6
1239............................................           59.40              74              17               8

1315............................................            6.24              74               7              19
1265............................................           12.18              73              16              11
1251............................................           20.92              70              16              13
1592............................................           46.99              68              11              21
1650............................................           24.92              68               3              28
1643............................................           22.02              67               1              33
1674............................................           22.02              67               1              32
1225............................................           46.99              66              11              23
1268............................................           16.97              65               4              31
1226............................................           21.45              64              11              26
1589............................................           20.92              64              30               5
1200............................................           86.65              63               5              32
1218............................................           86.65              63               5              32
1415............................................           20.00              63              29               7
1439............................................           46.99              63              11              27
1421............................................           13.00              62              27              11
1435............................................           11.56              62              25              13
1463............................................           12.18              62              13              25
1484............................................           11.56              62              25              13
1481............................................           39.12              60              35               5
1337............................................           57.17              59              17              24
1375............................................           20.67              59              21              20
1448............................................           57.17              59              17              24
1615............................................           20.67              58              21              21
1259............................................            8.31              57              23              20
1327............................................           20.67              57              21              23
1604............................................           20.00              55              22              23
1256............................................           21.63              54              41               5
1294............................................           21.63              54              41               5
1343............................................           21.63              54              41               5
1350............................................           21.63              54              41               5
1220............................................           21.54              53              40               6
1635............................................           21.23              52              41               7
1638............................................           39.00              48               3              48
1233............................................           11.31              46              41              14
1240............................................           21.23              44               3              53
1331............................................           16.93              44              12              44
1417............................................           39.00              44               3              53
1594............................................           16.93              42              12              46
1371............................................           20.10              40              16              44
1619............................................           20.10              40              16              43
1660............................................           16.93              39              11              50
1443............................................           20.00              38              57               5
1396............................................           20.43              35              61               4
1436............................................           20.10              35              15              50
1286............................................            5.67              33               2              65
1364............................................            5.67              32               2              66
1582............................................           24.59              30              13              57
1591............................................           24.59              30              13              57
1655............................................           24.59              30              13              57
1253............................................           12.94              29              60              11
1323............................................           12.94              29              60              11
1390............................................           12.94              29              60              11
1639............................................           12.94              29              60              11
1663............................................           12.94              29              60              11
1308............................................            6.15              27               1              72
1520............................................           19.86              27              34              38
1521............................................            6.15              27               1              72
1536............................................           10.65              27               0              73
1246............................................           20.00              26              65               9
1316............................................           20.00              26              65               9
1559............................................            5.00              26              19              55
1335............................................           20.30              25              55              21
1437............................................           21.20              25              50              25
1597............................................           21.20              25              49              26
1219............................................           11.25              20              71               8
1560............................................           11.09              18              76               5
1494............................................            5.22              17              54              28

1610............................................          163.39              17              10              73
1530............................................            5.22              15              53              32
1630............................................           22.60              15              84               2
1538............................................            8.42              10              89               1
1356............................................            8.23               8              91               1
----------------------------------------------------------------------------------------------------------------
\a\ The combined percentages of limestone, other raw materials, and fuels add to 100 percent.

    These data seem to indicate that although quarry mercury content is
important, other non-proprietary inputs can and do affect mercury
emissions as well, often to an equal or greater extent. Quarries with
similar limestone mercury content can and do have very different
mercury emissions. These facts, plus the general continuum in the
limestone mercury data, seem to mitigate against subcategorizing on
this basis for the great bulk of industry sources.
    Moreover, as stated above, subcategorization is limited by the CAA
to size, class, or type of source. Both EPA and advance industry
commenters \16\ applied various statistical analyses to the mercury
limestone quarry data set and these analyses indicated that there could
be populations of quarries that were statistically different. However,
it is unclear to us that a statistical difference in a population is
necessarily the same as a distinction by size, class, or type. More
compelling facts, at least in our present thinking, are the apparent
continuum of limestone mercury levels, and the fact that limestone
mercury levels are less of a driver of mercury emission levels than one
would expect if this is to be the basis for subcategorization across a
broad set of the facilities. EPA is also concerned that
subcategorization by quarry mercury content may allow some higher-
emitting facilities to do relatively less for compliance were they to
be part of a separate subcategory where mercury levels of best
performers were comparatively high. (Of course, these levels could be
reduced by adopting standards reflecting beyond-the-floor
determinations.) Conversely, the case could occur where a lower emitter
might be subject to a greater degree of control than a high emitter.
For example, if we were to establish a subcategory at 20 ppb mercury in
the limestone, kilns at just below the 20 ppb level might be required
to apply mercury controls while kilns just above the 20 ppb level,
which would likely include kilns that would determine the floor level
of control, would have to do nothing to meet the mercury standard.
---------------------------------------------------------------------------

    \16\ See Minutes of March 19, 2006 meeting between
representative of the Portland Cement Association and E. Craig,
USEPA.
---------------------------------------------------------------------------

    Much of this analysis, however, does not apply to the kilns at the
far end of the distribution, especially the two facilities shown in
Figure 1 which have the highest quarry mercury contents which quarries
appear to be outliers from the general population. These sources'
mercury emissions are related almost entirely to the limestone mercury
content, not to other inputs.
    However, EPA is not proposing to create a separate subcategory for
these high mercury sources. We note that if we set up a separate
subcategory for these facilities, even if we proposed a beyond-the-
floor standard based on the best estimated performance of control for
these two facilities, their emissions limit would potentially be 500 to
800 lb/MM tons clinker, which is well above any other kiln, even when
uncontrolled, in our data base, and 8 to 13 times the floor established
for other existing sources (assuming no further subcategorization).
Mercury in the air eventually settles into water or onto land where it
can be washed into water. Once deposited, certain microorganisms can
change it into methylmercury, a highly toxic form that builds up in
fish, shellfish and animals that eat fish. Fish and shellfish are the
main sources of methylmercury exposure to humans. (See section IV.4 for
further discussion of mercury health effects.) Mercury is one of the
pollutants identified for special control under the Act's air toxics
provision (see section 112c(6)), and kilns in a high-mercury
subcategory, no matter how well controlled, would still be allowed to
emit large amounts (at least pending a section 112(f) residual risk
determination)).
    EPA is also mindful of the holding of Brick MACT and other
decisions that EPA must account for raw material HAP contributions in
establishing MACT floors, and the fact that raw materials may be
proprietary or otherwise not obtainable category-wide does not relieve
EPA of that obligation. See, e.g. 479 F. 3d at 882-83.
    There are also competing considerations here. The concurring
opinion in Brick MACT supports subcategorization in situations
involving sources' dependence on high-HAP raw materials to avoid
situations where a level of performance achieved by some sources proves
unachievable by other sources even after application of best
technological controls, viewing such sources as of a different type
than others in the source category. 479 F. 3d at 884-85. A further
consideration is that one of the high mercury kilns here has
voluntarily entered into an enforceable agreement to install activated
carbon (the best control technology currently available so far as is
known) to control its mercury emissions and this agreement appears to
have the support of directly affected stakeholders (local citizen
groups, regional and state officials).\17\ The company is poised to
begin installation of the control technology. However, neither EPA nor
the company believe that this source could physically achieve the level
of the mercury floor derived from a single source category approach
(i.e., the no subcategorization approach proposed above) using
activated carbon alone. We do not currently have any data on the
possibility that this site may have portions of its existing quarry
that have lower mercury content, or if the site could apply different
mercury controls in addition to ACI to meet the proposed limit. Closure
of this kiln and possibly other high mercury emitting kilns is a
possible consequence of a single standard without subcategories.
---------------------------------------------------------------------------

    \17\ Minutes of meeting between EPA and representatives of Ash
Grove Cement. February 27, 2009.
---------------------------------------------------------------------------

    EPA repeats that it is not proposing for mercury any subcategories
for

mercury for the reasons discussed above. Nonetheless, this remains an
issue EPA intends to evaluate carefully based on public comment, and
expressly solicits comment addressing all aspects of determinations
whether or not to subcategorize. These comments should address not only
the issue of a high-mercury subcategory (addressing plants in the
upward right-hand tail of the distributional curve in Figure 1), but
other sources as well. EPA also solicits comment regarding non-
limestone inputs to cement kilns, and whether there is any potential
basis for considering a valid subcategorization approach involving such
materials.\18\
---------------------------------------------------------------------------

    \18\ One of these high-mercury sources suggested that because it
is an area source, EPA develop a mercury standard for it based upon
Generally Available Control Technology (GACT) rather than MACT. See
section 112(d)(5) of the Act. Aside from questions about whether use
of activated carbon is a generally available control technology
here, EPA has already determined that all cement kilns' mercury
emissions are subject to MACT under authority of section 112(c)(6).
See 63 FR at 14193.
---------------------------------------------------------------------------

Other Alternatives Considered for Mercury Standard
    EPA is proposing to rank sources by emission level in determining
which are best performing. We also considered another option of ranking
best performers based on their relative mercury removal efficiency, and
presenting a standard so-derived as an alternative to the standard
based on ranking by lowest emissions. The MACT floor for new sources is
to be based on the performance of the ``best controlled'' similar
source, and the term ``control'' can be read to mean control
efficiency. It can also be argued that the critical terms of section
112 (d)(3)--``best controlled'' (new)/``best performing'' (existing)--
do not specify whether ``best'' is to be measured on grounds of control
efficiency or emission level. See Sierra Club v. EPA, 167 F.3d 658, 661
(''average emissions limitation achieved by the best performing 12
percent of units' * * * on its own says nothing about how the
performance of the best units is to be calculated''). Existing source
floors determined and expressed in terms of control efficiency are also
arguably consistent with the requirement that the floor for existing
sources reflect ``average emission limitation achieved'', since
``emission limitation'' includes standards which limit the ``rate'' of
emissions on a continuous basis--something which percent reduction
standards would do. CAA section 302(k). There are also instances where
Congress expressed performance solely in terms of numerical limits,
rather than performance efficiency, suggesting that Congress was aware
of the distinction and capable of delineating it. See CAA section
129(a)(4).\19\
---------------------------------------------------------------------------

    \19\ See also section 112(i)(5)(A), which allows sources that
achieve early reductions based on measured rates of removal
efficiency a reprieve from MACT.
---------------------------------------------------------------------------

    There are also arguments that percent reduction standards are not
legally permissible. The Brick MACT opinion states, arguably in dicta,
that best performers are those emitting the least HAP (see 479 F. 3d at
880 (``section [112 (d)(3)] requires floors based on emission levels
actually achieved by best performers (those with the lowest emission
levels)'').\20\ More important, the opinion stresses that raw material
inputs must be accounted for in determining MACT floors. Id. at 882-83.
A problem with a percent reduction standard here is that it would
downplay the role of HAP inputs on emissions by allowing more HAP to be
emitted provided a given level of removal efficiency reflecting the
average of best removal efficiencies is achieved. For these reasons,
EPA is not proposing an alternative standard for mercury expressed as
percent reduction reflecting the average of the best removal
efficiencies. EPA solicits comment on this alternative from both a
legal and policy standpoint, however.
---------------------------------------------------------------------------

    \20\ The issue of whether best performers can be based on
source's removal efficiency was not presented in Brick MACT, or any
of the other decided cases.
---------------------------------------------------------------------------

2. Beyond the Floor Determination
    We are not proposing any beyond-the-floor standards for mercury.
When we establish a beyond the floor standard we typically identify
control techniques that have the ability to achieve an emissions limit
more stringent than the MACT floor. Under the proposed amendments, most
existing kilns would have to have installed both a wet scrubber and
activated carbon injection (ACI) for control of mercury, HCl and
THC.\21\ To achieve further reductions in mercury beyond what can be
achieved using wet scrubber and ACI in combination, the available
options would include closing the kiln and relocating to a limestone
quarry having lower mercury concentrations in the limestone,
transporting low-mercury limestone in from long distances, switching
other raw materials to lower the amount of limestone in the feed,
wasting CKD, and installing additional add-on control devices. For
reasons discussed further below we believe that all but the latter
option (add-on controls) are either cost prohibitive or too site
specific to serve as the basis of a national potential beyond the floor
standard. For that reason, we estimated the cost and incremental
reduction in mercury emissions associated with installing another
control device in series to the other controls. The add-on controls
considered included a wet scrubber and ACI. Because ACI is less costly
and is expected to have a higher removal efficiency as well as being
potentially capable of removing elemental mercury (using halogenated
carbon) which a scrubber cannot remove, we selected ACI as the beyond-
the-floor control option (i.e., the kiln would now have an additional
ACI system in series with the wet scrubber/ACI system required to meet
the MACT floors for mercury, THC, and HCl).
---------------------------------------------------------------------------

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

    We estimated the costs and emission reductions for a 1.2 million
tpy kiln as it would be representative of the impacts of other kilns.
Annualized costs for an additional ACI system would be $1.254 million
per year. The quantity of mercury leaving the upstream controls would
be an estimated 3.3 lb/yr. Assuming a 90 percent control efficiency,
the additional ACI system would remove about 3.0 lb/yr of mercury for a
cost-effectiveness of approximately $420,000 per lb of mercury
reduction. A 90 percent removal efficiency may be optimistic given the
lower level of mercury entering the device and a removal efficiency on
the order of 70 percent is more likely. At this efficiency, the
additional mercury controlled would be 2.3 lb/yr for a cost
effectiveness of approximately $540,000 per pound of mercury removed.
At either control efficiency, we believe cost of between $420,000 and
$540,000 per pound of mercury removed is not justified and we are
therefore not selecting this beyond-the-floor option.
    There are two potential feasible process changes that have the
potential to affect mercury emissions. These are removing CKD from the
kiln system and substituting raw materials, including fly ash, or
fossil fuels with lower-mercury inputs. Although substituting low-
mercury materials and fuel may be feasible for some facilities, this
alternative would depend on site-specific circumstances and, therefore,
must be evaluated on a site-by-site basis and EPA's current view is
that it would not be a uniformly applicable (or quantifiable) control
measure on which a national standard could be based (although as noted
earlier, EPA is expressly soliciting quantified comment regarding
potential substitutability of non-limestone kiln inputs). In addition,
in the case of substitution of lower

mercury inputs, we believe that mandating lower mercury materials (such
as a ban on fly ash containing mercury as a raw material) would not
result in mercury reduction beyond those achieved at the floor level of
control.
    Based on material balance data (feed and fuel usage, control device
catch recycling and wasting, and mercury concentrations) that we
gathered with our survey of 89 kilns, 58 percent of kilns waste some
amount of CKD while 42 percent waste none. Among kilns that waste CKD,
the percentage reduction in mercury emissions by wasting CKD ranged
from 0.13 percent to 82 percent, with an average of 16.5 percent and
median of 7 percent. For kilns that waste some CKD, CKD as a percentage
of total feed ranges from 0.16 percent to 13.7 percent, with a mean of
4.5 percent. Any additional emission reductions that can be achieved by
wasting CKD depend on several site-specific factors including:
     The concentration of mercury in raw feed and fuel
materials.
     The concentration of mercury in the CKD.
     The amount of CKD already being wasted.
     The dynamics of mercury recirculation and accumulation--
Internal loops for mercury exist between the control device and kiln
feed storage and the kiln for long dry and wet kilns. For preheater and
precalciner kilns, there is usually an additional internal loop
involving the in-line raw mill. These internal loops and the
distribution of mercury throughout the process are not predictable and
can only be determined empirically.
     Mercury speciation may affect the extent to which mercury
accumulates in the CKD, with particulate and oxidized mercury more
likely to accumulate while elemental mercury is likely emitted and not
affected by CKD wasting.
    Reducing mercury emissions through the wasting of CKD may be
feasible for some kilns that do not already waste CKD or by wasting
additional CKD for some kilns that already practice CKD wasting.
However the degree to which CKD can be used to reduce mercury emissions
cannot be accurately estimated due to several factors. For example,
increasing the amount of CKD wasted would result in a reduction in the
mercury concentration of the CKD, so that, over time, the effectiveness
of wasting CKD decreases. We do not have long-term data to quantify the
relationship between amount of CKD wasted, CKD mercury concentration
and emissions.
    The ability to reduce mercury emissions by wasting more CKD also is
affected by the mercury species present. The particulate and oxidized
species of mercury can accumulate in CKD, but not the elemental form.
Therefore wasting CKD will not necessarily control elemental mercury.
We do not have data that would allow us to quantify the effect of
mercury speciation. By wasting CKD, additional raw materials would be
required to replace the CKD as well as additional fuel to calcine the
additional raw materials, thereby offsetting to some extent the
benefits of wasting CKD. There is the further potential consideration
of additional waste generation, an adverse cross-media impact EPA is
required to consider is making beyond-the-floor determinations. The
interaction of these factors is complex and has not been adequately
studied.
    One cement plant has investigated the potential to reduce mercury
emissions by wasting CKD. This facility, using mercury CEMS and
material balance information, estimated that wasting 100 percent of CKD
when the raw mill is off (about 19,000 tons of CKD or 16 percent of
total baghouse catch, or 1 percent of total feed) would reduce mercury
emissions by about 4 percent. This facility did not estimate the
reductions in mercury emissions by wasting more CKD. As with the
potential to reduce mercury emissions using raw materials substitution,
the effectiveness of CKD wasting in reducing emissions may provide
cement plants the ability to reduce mercury emissions but the degree of
reduction will have to be determined on a site-by-site basis.
    Because the degree to which mercury emissions can be reduced by
material substitutions or through the wasting of CKD are site specific,
these process-related work practices were not considered as beyond-the-
floor options.
    As a result of these analyses, we determined that, considering the
technical feasibility and costs, there is no reasonable beyond the
floor control option, and are proposing a mercury emission limit based
on the MACT floor level of control.

C. Determination of MACT for THC Emissions From Major and Area Sources

    The limits for existing and new sources we are proposing here apply
to both area and major new sources. We have applied these limits to
area sources consistent with section 112(c)(6). See 63 FR 14193 (THC as
a surrogate for the 112(c)(6) HAP polycyclic organic matter and
polychlorinated biphenyls, plus determination to control all THC
emissions from the source category under MACT standards).
1. Floor Determination
Selection of Existing Source Floor
    For reasons previously discussed in the initial proposal of the
Portland Cement NESHAP (63 FR 14197, March 24, 1998), we are proposing
to use THC as a surrogate for non-dioxin organic HAP that are emitted
from the kiln (as is the current rule). The THC data used to develop
the MACT floor were obtained from 12 kilns using CEMS to continuously
measure the concentration of THC exiting each kiln's stack. Only kilns
1 (regenerative thermal oxidizer (RTO)) and kilns 11 and 12 (ACI) have
emissions controls which remove or destroy THC. We also obtained THC
data from manual stack tests, typically based on 3 one hour runs per
test. The CEMS data are superior to the results of a single stack test
for characterizing the long term performance and in determining the
best performing kilns with respect to THC emissions for several
reasons. The manual stack test is of short duration and only represents
a snapshot in time; consequently, it provides no information on the
variability in emissions over time due to changes in raw material feed
or in kiln operating conditions. In contrast, the CEMS data include
measurements that range from 31 consecutive days to almost 900 days of
operation for the various kilns. This extended duration of the CEMS
test data gives us confidence that for any particular kiln CEMS data
will capture the variability associated with the long-term THC
emissions data, and thus give the most accurate representation of a
source's performance. In addition, a MACT standard based on CEMS data
would be consistent with the way we are proposing to implement the THC
emission limit (i.e., by requiring continuous monitoring with a THC
CEMS).
    In order to set MACT floors we are ranking the kilns based on the
average THC emissions levels (in ppmv) achieved (i.e., each kiln's
averaged performance, averaged over the number of available
measurements. This ranking is shown in Table 4.

                                Table 4.--Summary of THC CEMS Data and MACT Floor
----------------------------------------------------------------------------------------------------------------
                                                   Number of
                Kiln                   Average      readings         Kiln type             In-line raw mill
----------------------------------------------------------------------------------------------------------------
Kiln 1.............................          4.0           35  Preheater/precalciner  Yes.
Kiln 2.............................          5.6          695  Wet..................  No.
Kiln 3.............................          6.8          692  Long dry.............  No.
Kiln 4.............................          6.8           31  Preheater/precalciner  Yes.
Kiln 5.............................         11.1          702  Long dry.............  No.
Kiln 6.............................         23.7          470  Preheater/precalciner  No.
Kiln 7.............................         45.0          742  Preheater/precalciner  Yes.
Kiln 8.............................         51.6          774  Preheater/precalciner  Yes.
Kiln 9.............................         51.9          843  Preheater/precalciner  Yes.
Kiln 10............................         62.8          880  Preheater/precalciner  Yes.
Kiln 11 and Kiln 12 Combined.......        748.1          790  Wet..................  No.
Existing Source Average (ppmvd at            4.8
 7% O2, propane).
Variability (t*vT\0.5\)............          1.9
Existing Source 99th percentile                7
 (ppmvd at 7% O2, propane).
New Source Average (ppmvd at 7% O2,          4.0
 propane).
Variability (t*vT\0.5\)............          1.5
New Source 99th percentile (ppmvd              6
 at 7% O2, propane).
----------------------------------------------------------------------------------------------------------------

    The average performance of the best performing 12 percent of kilns
(2 kilns) is 4.8 ppmvd THC (a daily average expressed as propane at 7
percent oxygen). We calculated variability based on the variances in
the performance of the two lowest emitting kilns. This includes day-to-
day variability at the same kiln, variability among the two lowest
emitting kilns, and because one dataset included 695 daily
measurements, it represents long term variability at a single kiln. We
calculated the MACT floor (7 ppmvd) based on the UPL (upper 99th
percentile) as described earlier from the average performance of the 2
lowest emitting kilns, Student's t-factor, and the total variability,
which was adjusted to account for the lower variability when using 30
day averages.
    In this case the proposed new and existing source MACT floors are
almost identical because the best performing 12 percent of kilns (for
which we have emissions information) is only two sources. The reason we
look to the best performing 12 percent of sources is that the cement
kiln source category consists of 30 or more kilns. Section 112(d)(3)(A)
of the Clean Air Act provides that standards for existing sources shall
not be less stringent than ``the average emission limitation achieved
by the best performing 12 percent of the existing sources (for which
the Administrator has emissions information), * * * in the category or
subcategory for categories and subcategories with 30 or more sources.''
A plain reading of the above statutory provisions is to apply the 12
percent rule in deriving the MACT floor for those categories or
subcategories with 30 or more sources. The parenthetical ``(for which
the Administrator has emissions information)'' in section 112(d)(3)(A)
modifies the best performing 12 percent of existing sources, which is
the clause it immediately follows.
    However, in cases where there are 30 or more sources but little
emission data this results in only a few kilns setting the existing
source floor with the result that the new and existing source MACT
floors are almost identical. In contrast, if this source category had
less than 30 sources, we would be required to use the top five best
performing sources, rather than the two that comprise the top 12
percent. Section 112 (d)(3)(B).
    We are seeking comment on whether, with the facts of this
rulemaking, we should consider reading the intent of Congress to allow
us to consider five sources rather than just two. First, it seems
evident that Congress was concerned that floor determinations should
reflect a minimum quantum of data: At least data from five sources for
source categories of less than 30 sources (assuming that data from five
sources exist). Second, it does not appear that this concern would be
any less for source categories with 30 or more sources. The concern, in
fact, would appear to be greater.\22\ We note further that if we were
to use five sources as best THC performers here, the existing source
floor would be 10 ppmvd. We are specifically requesting comment on
interpretive and factual issues relating to the proposed THC floors,
and also reiterate requests for further THC performance data,
especially from kilns equipped with CEMs.
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    \22\ As noted, basing the proposed existing source THC floor on
data from two sources (i.e. 12 percent of the 15 sources for which
we have CEM data) largely eliminates the distinction between new and
existing source THC floors. Yet this is an important statutory
distinction.
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Selection of New Source MACT Floor
    The new source MACT floor would be the best performing similar
source accounting for variability, which would be 6 ppmvd. We used the
same procedure in estimating variability for the new source based on
the 35 observations reported.
Alternative Organic HAP Standards
    EPA is also proposing an alternative floor for non-dioxin organic
HAP, based on measuring the organic HAP itself rather than the THC
surrogate. This equivalent alternative limit would provide additional
flexibility in determining compliance, and it would be appropriate for
those rare 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. A previous study that compared total organic HAP to THC found
that the organic HAP was 23 percent of the THC. We also analyzed
additional data submitted during the development of this proposed rule
that included simultaneous measure of organic HAP species and THC. Data
were available from tests at five facilities, and the organic HAP
averaged 24 percent of the THC. Based on these analyses, we are
proposing an equivalent alternative

emission limit for organic HAP species of 2 ppmv (i.e., 24 percent of
the 7 ppmv MACT standard for THC) for existing sources and 1 ppmvd for
new sources. The specific organic compounds that will be measured to
determine compliance with the alternative to the THC limit are benzene,
toluene, styrene, xylene (ortho-, meta-, and para-), acetaldehyde,
formaldehyde, and naphthalene. These were the organic HAP species that
were measured along with THC in the cement kiln emissions tests that
were reviewed. Nearly all of these organic HAP species were identified
in an earlier analysis of the organic HAP concentrations in THC in
which the average concentration of organic HAP in THC was 23 percent.
Other Options Considered
    We also examined the THC results to determine if subcategorization
by type of kiln was warranted and concluded that the data were
insufficient for determining that a distinguishable difference in
performance exists based on the type of kiln. The top performing kilns
in Table 4 include various types: wet, long dry, and preheater/
precalciner kilns; older (wet kilns) and newer (precalciner kilns); and
those with and without in-line raw mills. Although the type of kiln and
the design and operation of its combustion system may have a minor
effect on THC emissions, the composition of the feed and the presence
of organic compounds in the feed materials apparently have a much
larger effect. For example, organic compounds in the feed materials may
volatilize and be emitted before the feed material reaches the high
temperature combustion zone of the kiln where they would have otherwise
been destroyed.
    We also evaluated creating separate subcategories for kilns with
in-line raw mills and those without. With an in-line raw mill kiln,
exhaust is used to dry the raw materials during the grinding of the raw
meal. This drying step can result in some organic material being
volatilized, thus increasing the THC emissions in the kiln exhaust.
This means that kilns with in-line raw mills would, on average, have
higher emissions than kilns without in-line raw mills. The existence,
or absence, of a raw mill is believed to have a distinct effect on
emissions of THC, as one would expect. It is difficult to generalize
that difference because the effect of the raw mill will vary based on
the specific organic constituents of the raw materials. In tests at one
facility, THC emissions, on average, were 35 percent higher with the
raw mill on than when the raw mill was off.\23\
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    \23\ E-mail and attachments. B. Gunn, National Cement Company of
Alabama to K. Barnett. USEPA. March 12, 2009. THC Mill on/Mill Off
Variability.
---------------------------------------------------------------------------

    This physical difference could justify subcategorization based on
the presence of an in-line raw mill. There are also potential policy
reasons for doing so. By not subcategorizing, use of in-line raw mills
may be discouraged because, to meet a THC standard, in-line raw mill-
equipped kilns would potentially have to utilize an RTO. Use of RTOs
has various significant adverse environmental consequences, including
increase in emissions of criteria pollutants, and significant extra
energy utilization with attendant increases in carbon dioxide
(CO2) gas emissions.\24\
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    \24\ Summary of Environmental and Cost Impacts of Proposed
Revisions to Portland Cement NESHAP (40 CFR Part 63, subpart LLL),
April 15, 2009.
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    EPA has performed floor calculations for subcategories of kilns
with and without in-line raw mills. The result of that calculation,
where we were using the top 12 percent, was that the floor for kilns
with in-line raw mills was actually lower than the floor for those
without, which is atypical: sources with in-line raw mills will
typically have higher emissions because of the extra volatilization. We
believe this result is the artifact of the small data set used to
calculate the existing source MACT floor. Based on these results, we
have concluded that the current data are not sufficient to allow us to
subcategorize by the presence of an in-line raw mill, but would
consider subcategorizing if additional data become available. We are
specifically requesting comment on subcategorization by the presence or
absence of an in-line raw mill and requesting data on this issue.
2. Beyond the Floor Determination
    Practices and technologies that are available to cement kilns to
control emissions of organic HAP include raw materials material
substitution, ACI systems and limestone scrubber and RTO. We do not
think it is appropriate to develop a beyond-the-floor control option
based on material substitution here because substitution options are
site specific.
    We examined the use of either ACI systems or RTO (with a dedicated
wet scrubber) \25\ as the basis for potential beyond-the-floor THC
standards for existing and new sources. (We did not examine other
beyond-the-floor regulatory options for existing or new sources because
there are no controls that would, on average, generate a greater THC
reduction than a combination of a wet scrubber/RTO.) These technologies
are currently in limited use in the source category. At one facility,
activated carbon is injected into the flue gas and collected in the PM
control device. The activated carbon achieved a THC emissions reduction
of approximately 50 percent, and the collected carbon is then injected
into the kiln in a location that insures destruction of the collected
THC. The THC emissions from this facility are the highest for any
facility for which we have data due to very unusual levels of organic
material in the limestone and may not be representative of the
performance that can be achieved by kilns with more typical THC
emissions.\26\
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    \25\ A wet scrubber is needed as a pretreatment step before
gases are amenable to destruction in an RTO.
    \26\ The same facility that uses ACI has a second control scheme
for THC consisting of a wet scrubber/RTO in series. However, due to
operational problems, this system has not operated more than a few
months at a time and data from it are not representative of the
performance of these control devices.
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    ACI has been demonstrated in other source categories, such as
various types of waste incinerators including municipal waste
incinerators, to reduce dioxin/furan by over 95 percent.\27\ The actual
performance of ACI systems on cement kiln THC emissions are expected to
be less than that achieved on dioxin/furan emissions as kiln flue gases
are a mixture of volatile and semi-volatile organic compounds, which
vary according to the organic constituents of raw materials. We have
therefore conservatively estimated that ACI systems can reduce THC
emissions by 75 to 80 percent. A second facility has a continuously
operated limestone scrubber followed by an RTO. This facility has been
emission tested and showed volatile organic compound (VOC), which are
essentially the same as THC, emission levels of 4 ppmv (at 7 percent
oxygen), and currently has a permit limit for VOC of approximately 9
ppmv. The RTO has a guaranteed destruction efficiency of 98 percent of
the combined emissions of carbon monoxide and THC. Based on this
information, we believe this facility represents the best possible
control performance to reduce THC emissions.
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    \27\ (Chi and Chang, Environmental Science and Technology, vol.
39, issue 20, October 2005; Roeck and Sigg, Environmental
Protection, January 1996).
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    In assessing the potential beyond-the-floor options for THC, we
first determined that most existing kilns would have to install an ACI
system for control of THC and/or mercury. A few kilns would be expected
to install an RTO in order to get the THC proposed reductions. To
evaluate the feasibility of

beyond-the-floor controls, we assumed that a kiln already expected to
install an ACI system would install in series an RTO including a wet
scrubber upstream of the RTO to protect the RTO. We estimated the costs
and emission reductions for a 1.2 million tpy kiln as the cost
effectiveness of the beyond-the-floor option would be similar for all
kilns. Annualized costs for an additional RTO system would be $3.8
million per year. The quantity of THC leaving the upstream controls
would be an estimated 18 tpy. At higher THC concentrations, for example
15 ppmv and above, an RTO will have a removal efficiency of about 98
percent. This mass of THC leaving the device upstream of and entering
the RTO is equivalent to a THC concentration of about 3 ppmv. At this
low level, an RTO's removal efficiency is expected to be no better than
50 percent. At a 50 percent control efficiency, the RTO would reduce
THC emission by about 9 tpy for a cost-effectiveness of approximately
$411,000 per ton of THC removal. If the organic HAP fraction of the THC
is 24 percent, 2 tpy of organic HAP would be removed at a cost
effectiveness of approximately $1.7 million per ton of organic HAP
removed. At a cost effectiveness of $411,000 per ton of THC and $1.7
million per ton of organic HAP, we believe the cost of the additional
emission reduction is not justified (this is a far higher level than
EPA has deemed justified for non-dioxin organic HAP in other MACT
standards, for example). In addition to the high cost of control, the
additional energy requirements, 7.1 million kwh/yr and 81,000 MMBtu/yr,
would be significant. Increased CO2 emissions attributable
to this energy use would be on the order of 9,900 tpy per source.\28\
The additional energy demands would also result in increased emissions
of NOX (20 tpy), CO, (8 tpy), SO2 (27 tpy), and
PM10 (1 tpy) per source. Because of the high costs and minimal
reductions in THC and organic HAP as well as the secondary impacts and
additional energy requirements, we are not selecting this beyond-the-
floor option.
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    \28\ Summary of Environmental and Cost Impacts of Proposed
Revisions to Portland Cement NESHAP (40 CFR Part 63, subpart LLL),
April 15, 2009.
---------------------------------------------------------------------------

    Therefore we are proposing for cement kilns an existing source THC
emissions limit of 7 ppmvd and a new source limit of 6 ppmvd, measured
as propane and corrected to 7 percent oxygen. We are also proposing for
an alternative equivalent organic HAP emissions limit of 2 ppmvd for
existing kilns and 1 ppmvd for new kilns.
THC Standard for Raw Material Dryers
    Some plants may dry their raw materials in separate dryers prior to
or during grinding. See 63 FR at 14204. This drying process can
potentially lead to organic HAP and THC emissions in a manner analogous
to the release of organic HAP and THC emissions from kilns when hot
kiln gas contacts incoming feed materials. The methods available for
reducing THC emissions (and organic HAP) is the same technology
described for reducing THC emissions from kilns and in-line kiln/raw
mills. Based on the similarity of the emissions source and controls, we
are also proposing to set the THC emission limit of materials dryers at
7 ppmvd (existing sources) and 6 ppmvd (new sources).
    The current NESHAP has an emissions limit of 50 ppmvd for new
greenfield sources. The limit is less stringent than the proposed
changes in the THC emissions limits for new (as well as existing)
sources. For that reason, we are proposing to remove the 50 ppmvd
emissions limit for this rule.

D. Determination of MACT for HCl Emissions From Major Sources

    In developing the MACT floor for HCl, we collected over 40 HCl
emissions measurements from stack tests based on EPA Methods 321 and
26. Studies have suggested that Method 26 is biased significantly low
due to a scrubbing effect in the front half of the sampling train (see
63 FR at 14182). Because of this bias, we used the HCl data measured at
27 kilns using Method 321 in determining the proposed floors for
existing and new sources. The data in ppmv corrected to 7 percent
oxygen (O2) were ranked by emissions level and the top 12
percent (4 kilns) lowest emitting kilns identified.\29\ The top 4 kilns
were limited to major sources, and to sources where we had a minimum of
three test runs to allow us to account for variability in setting the
floor. (Note that neither of these decisions significantly changed the