Standards of Performance for Portland Cement Plants

(40 CFR 60 Subpart F)

Response to Public Comments

US Environmental Protection EPA

Office of Air Quality Planning and Standards

Sector Policies and Programs Division

Metals and Minerals Group

Research Triangle Park, NC 27711

August 6, 2010

Table of Contents

  TOC \o "2-5" \h \z \t "Heading 1,1"    HYPERLINK \l "_Toc268873174"
1. 	Introduction	  PAGEREF _Toc268873174 \h  1

  HYPERLINK \l "_Toc268873175"  2	Legal Issues Related to EPA’s
Interpretation of the CAA	  PAGEREF _Toc268873175 \h  4

  HYPERLINK \l "_Toc268873176"  2.1	Best Demonstrated Technology
PAGEREF _Toc268873176 \h  4

  HYPERLINK \l "_Toc268873177"  2.2.	Greenhouse Gases	  PAGEREF
_Toc268873177 \h  4

  HYPERLINK \l "_Toc268873178"  2.3	Emission Limits	  PAGEREF
_Toc268873178 \h  6

  HYPERLINK \l "_Toc268873179"  2.4	Pollutants not Included (VOC, PM2.5)
  PAGEREF _Toc268873179 \h  9

  HYPERLINK \l "_Toc268873180"  2.5	General	  PAGEREF _Toc268873180 \h
10

  HYPERLINK \l "_Toc268873181"  3	Applicability	  PAGEREF _Toc268873181
\h  12

  HYPERLINK \l "_Toc268873182"  3.1	Modified Kilns	  PAGEREF
_Toc268873182 \h  12

  HYPERLINK \l "_Toc268873183"  4	Emission Limits	  PAGEREF
_Toc268873183 \h  16

  HYPERLINK \l "_Toc268873184"  4.1	General	  PAGEREF _Toc268873184 \h
16

  HYPERLINK \l "_Toc268873185"  4.2	Format	  PAGEREF _Toc268873185 \h
16

  HYPERLINK \l "_Toc268873186"  4.3	NOx	  PAGEREF _Toc268873186 \h  16

  HYPERLINK \l "_Toc268873187"  4.4	SO2	  PAGEREF _Toc268873187 \h  24

  HYPERLINK \l "_Toc268873188"  4.5	PM	  PAGEREF _Toc268873188 \h  30

  HYPERLINK \l "_Toc268873189"  4.6	Opacity	  PAGEREF _Toc268873189 \h
35

  HYPERLINK \l "_Toc268873190"  4.7	VOC and CO	  PAGEREF _Toc268873190
\h  36

  HYPERLINK \l "_Toc268873191"  4.9	Fugitives	  PAGEREF _Toc268873191 \h
 37

  HYPERLINK \l "_Toc268873192"  4.10	Overall Achievability	  PAGEREF
_Toc268873192 \h  37

  HYPERLINK \l "_Toc268873193"  5	Monitoring and Recordkeeping	  PAGEREF
_Toc268873193 \h  39

  HYPERLINK \l "_Toc268873194"  5.1	SO2	  PAGEREF _Toc268873194 \h  39

  HYPERLINK \l "_Toc268873195"  5.2	PM	  PAGEREF _Toc268873195 \h  40

  HYPERLINK \l "_Toc268873196"  5.3	Opacity	  PAGEREF _Toc268873196 \h
40

  HYPERLINK \l "_Toc268873197"  5.4	CEMS	  PAGEREF _Toc268873197 \h  41

  HYPERLINK \l "_Toc268873198"  5.5	Clinker Production	  PAGEREF
_Toc268873198 \h  42

  HYPERLINK \l "_Toc268873199"  6	Test Methods and Procedures	  PAGEREF
_Toc268873199 \h  43

  HYPERLINK \l "_Toc268873200"  7	Impacts	  PAGEREF _Toc268873200 \h  44

  HYPERLINK \l "_Toc268873201"  7.1	Cost and Cost Effectiveness
PAGEREF _Toc268873201 \h  44

  HYPERLINK \l "_Toc268873202"  7.2	Environmental and Energy	  PAGEREF
_Toc268873202 \h  46

  HYPERLINK \l "_Toc268873203"  7.3	Economic	  PAGEREF _Toc268873203 \h
48

  HYPERLINK \l "_Toc268873204"  7.4	Multipollutant	  PAGEREF
_Toc268873204 \h  49

  HYPERLINK \l "_Toc268873205"  8	Miscellaneous	  PAGEREF _Toc268873205
\h  50

  HYPERLINK \l "_Toc268873206"  8.1	Proposed Rule	  PAGEREF
_Toc268873206 \h  50

  HYPERLINK \l "_Toc268873207"  8.2	Technical Support Document	  PAGEREF
_Toc268873207 \h  51

List of Tables

  TOC \h \z \t "Title_Table" \c    HYPERLINK \l "_Toc268873732"  Table
1-1. List of Commenters on Amendments to 40 CFR 60 Subpart F
Proposed June 16, 2008 (73 FR 34072)	  PAGEREF _Toc268873732 \h  2

1. 	Introduction

On June 16, 2008 the U.S. Environmental Protection Agency (EPA proposed
to amend the New Source Performance Standards (NSPS) for portland cement
plants in 40 CFR 60 subpart F (hereafter referred to in this document as
“Subpart F”) to revise emission limits and compliance requirements
for affected facilities which commence construction, reconstruction, or
modification after June 16, 2008. The proposed amendments also include
additional testing and monitoring requirements for affected sources.
Initially, a 60-day period ending August 15, 2008, was provided for the
public to submit comments to EPA regarding the proposed Subpart F
amendments. In response to a request from commenters, the public comment
period was extended by EPA an additional 45 days and ended September 30,
2008. This document presents a summary of the public comments that the
EPA received on the proposed Subpart F amendments.

A total of 23 sets of comments were received by EPA regarding the
proposed Subpart F amendments. Some of the comment sets were signed or
submitted on behalf of multiple commenters. Also, in some cases
duplicate comment sets from the same commenter were received. Table 1-1
lists the names of the commenters and their affiliations for each of the
comment sets received regarding the proposed Subpart F amendments. Some
commenters also submitted supplemental information and data to support
their comments. This document presents a summary of each substantive
comment received by EPA from the commenters listed in Table 1-1. The
comment summaries are grouped by topic in Sections 2 through 8 as
follows:

Section 2–Legal Issues Related to EPA’s Interpretation of the CAA

Section 3–Applicability

Section 4–Emission Limits

Section 5–Monitoring and Recordkeeping

Section 6–Test Methods and Procedures

Section 7–Impacts

Section 8–Miscellaneous Comments

Table 1-1. List of Commenters on Amendments to 40 CFR 60 Subpart F
Proposed June 16, 2008 (73 FR 34072)

Docket No. EPA-HQ-OAR-2007-0877	Commenter Name, Affiliation, and Date
Received

056	Anonymous Public Comment

August 15, 2008

057	Kevin Batchelder

EnviroLogix, Inc.

July 10, 2008

059	Al Armendariz, Ph.D.

Private Citizen

September 17, 2008

060	A. A. Linero, P.E., Program Administrator

Bureau of Air Regulation

Florida Department of Environmental Protection

September 29, 2008

061	Michael H. Winek

Babst, Calland, Clements, and Zomnir

On behalf of Armstrong Cement and Supply Corporation

September 30, 2008

062	Edmund G. Brown Jr., Attorney General of California

Joseph R. Biden, III, Attorney General of Delaware

Martha Coakley, Attorney General of Massachusetts

Andrew M. Cuomo, Attorney General of New York

Hardy Myers, Attorney General of Oregon

William H. Sorrell, Attorney General of Vermont

September 30, 2008

063	Carolyn Slaughter, Program Development Manger

Institute of Clear Air Companies (ICAC)

September 30, 2008

064	Andrew T. O’Hare, Vice President Regulatory Affairs

Portland Cement Association (PCA)

September 30, 2008

065	Timothy Ballo

James Pew

Janette Brimmer

Earthjustice on behalf of Clean Air Task Force and Downwinders At Risk

September 30, 2008

066	Melanie Sattler, Ph.D, P.E.

Private Citizen

September 30, 2008

067	Shelly Kaderly, Air Quality Division Administrator

Nebraska Department of Environmental Quality (NDEQ)

September 30, 2008

068	Robert Hodanbosi, Co-Chair Permitting Committee

Ursula Kramer, Co-Chair Permitting Committee

National Association of Clean Air Agencies (NACAA)

September 30, 2008

069	J. Jared Snyder, Assistant Commissioner

Office of Air Resources, Climate Change, and Energy

New York State Department of Environmental Conservation

September 30, 2008

070	Myra C. Reece, Chief

Bureau of Air Quality

South Carolina Department of Health and Environmental Control

September 30, 2008

071	Mohsen Nazemi, P.E., Deputy Executive Officer

Engineering and Compliance

South Coast Air Quality Management District (AQMD)

September 30, 2008

072	Downwinders At Risk

September 30, 2008

073	Craig S. Campbell, Vice President

Environment and Government Affairs

Lafarge North America

Cement Division

September 30, 2008

074	Steven Miller, Product Manager

Pyroprocessing Technology

Ove L. Jepsen, Senior Vice President, North America

FLSmidth Inc

September 29, 2008

075	Spencer Weitman, President

National Cement Company of Alabama, Inc.

September 30, 2008

076, 082*	Mark S. Terry, President

Polysius Corp, a ThyssenKrupp Technologies Company

September 26, 2008

077	Richard T. Cusick, President

Humboldt Wedag, Incorporated

September 22, 2008

078	Michael Pelan and Craig Campbell

Environment and Government Affairs

Lafarge North American

Cement Division

June 30, 2008

079**	Andrew T. O’Hare, Vice President

Regulatory Affairs

Portland Cement Association (PCA)

June 17, 2008

080	Andrew T. O’Hare, Vice President Regulatory Affairs

Portland Cement Association (PCA)

September 25, 2008

081	Roger Brower, Principal

Zephyr Environmental Corporation

June 09, 2008

083	Satish Sheth

Vice President – Environmental U.S. Operations

Cemex, Incorporated

May 05, 2009

*Duplicate copies of same comments entered in docket.

** Request for extension of public comment period.

2	Legal Issues Related to EPA’s Interpretation of the CAA

2.1	Best Demonstrated Technology

Comment: One commenter (68) agrees with EPA’s approach of basing best
demonstrated technology (BDT) on recently issued state permit data and
best available control technology (BACT) determinations developed as
part of new source review (NSR) as well as EPA’s assessment that the
main difference between BACT and BDT determinations for purposes of NSPS
is that a BACT determination is made on a site-specific basis.

Response: In addition to state permit limits and BACT determinations, we
also reviewed emissions data to verify that the emission limits for new
sources were reasonable.

Comment: Various commenters (59, 68) urge EPA to require the portland
cement industry to utilize BDT and state that selective catalytic
reduction (SCR) will provide the greatest nitrogen oxide (NOx)
reductions in addition to other benefits. The commenter states that EPA
is required to look toward emerging technologies in determining what
emissions reductions have been adequately demonstrated. Commenter 68
states that under CAA section 111, EPA can determine that a system has
been “adequately demonstrated” even if the majority of sources are
not utilizing it and, citing the D.C. Circuit Court of Appeals with
regard to cement plants, “‘[A]dequately demonstrated’ does not
require that any cement plant now in existence be able to meet the
proposed standards. Section 111 looks toward what may be fairly
projected for the regulated future, rather than the state of the art at
present, since it is addressed to standards for new plants…”.
According to the commenter, the D. C. Circuit has also held that
“…Congress also meant for emerging technologies to be given
consideration when EPA promulgates NSPS.” (see Sierra Club v. Costle).
As part of its discussion of SCR as BDT, the commenter cites various
studies as demonstrating the performance of SCR at coal-fired power
plants and successful application of SCR at a cement plant in Germany;
the co-benefits achieved through control of other pollutants; and cost
effectiveness.

Response: See preamble for the response.

2.2.	Greenhouse Gases

Comment: One commenter (64) supports EPA’s decision not to expand the
revised NSPS for portland cement plants to address emissions of GHGs.
Citing a ruling by the D.C. Circuit Court, the commenter states that EPA
is not obligated to address any particular pollutants when issuing or
revising NSPS. The commenter also states that the Supreme Court’s
Massachusetts v. EPA decision addressed EPA’s regulation of GHG
emissions from motor vehicles under CAA section 202(a)(1), but nothing
in that decision or any other court decision requires EPA to regulate
GHGs through NSPS. Commenter 64 states that there is no reason to
believe that standards for GHG emissions in the portland cement NSPS
would be an effective or appropriate means of climate change mitigation
and that EPA and Congress are currently grappling with the best
approaches for addressing climate change and those questions are best
answered after careful study and public debate, rather than
short-circuited by applying NSPS to GHGs. According to the commenter, it
is unlikely that an NSPS standards for GHGs at cement plants would
produce any meaningful reduction even in GHG emissions from new cement
plants: the only known method for controlling carbon dioxide emissions
from cement plants is efficient fuel combustion, and cement plant
operators already have large financial incentives to minimize fuel usage
to the extent practicable.

Response: See the Federal Register notice for the final amendments for
the response this comment. EPA notes further that the commenter is
correct that the Supreme Court’s decision in State of Massachusetts v.
EPA does not require EPA to address GHG emissions from cement kilns in
this rule. On the other hand, that opinion holds that GHGs are
pollutants under the Act, which brings GHGs under the potential
authority of section 111 (like any other pollutant).

Comment: Several commenters (62, 65, 69) objected to EPA not proposing
standards for greenhouse gas (GHG) emissions under the proposed NSPS.
One commenter (62) criticizes EPA’s decision to not propose any NSPS
for GHG emissions from portland cement plants. The commenter states that
even though the courts have confirmed that GHGs are air pollutants
subject to regulation under the CAA, EPA has not issued any such
standards, instead issuing an Advance Notice of Proposed Rulemaking
(ANPR) that seeks public comment on whether to regulate GHG emissions
under the CAA at all. Commenter 62 protests this course of action, and
request that EPA revise the proposed rule to include NSPS for GHG
emissions.

According to commenter 62, EPA’s failure to propose NSPS for GHGs in
the proposed rule violates §111 of the CAA (42 U.S.C. §7411), which
requires EPA to determine whether GHG emissions emitted by cement plants
may endanger public health or welfare, and to promulgate NSPS for each
air pollutant emitted by cement plants that contributes significantly to
global warming pollution. The commenter states that as the second
largest industrial source of carbon dioxide emissions in the United
States (emitting 45.7 million metric tons of carbon dioxide in 2006),
the cement industry contributes significantly to GHG emissions and there
can be no serious dispute that GHG emissions endanger public health
and/or welfare. The ANPR that EPA issued instead is no substitute for
action and does not commit to regulating GHG emissions from any source.

Commenters 65 and 69 submitted several exhibits in support of their
comments. A summary of the comments is presented here. To review the
entire comment, please refer to the comment at www.regulations.gov.

The commenter states that:

EPA is required by §111 to promulgate NSPS for all pollutants emitted
by a regulated source category including CO2 emission from cement plants
and EPA’s assertion that §111 does not compel the agency to regulate
CO2 emissions is contrary to the Act’s plain language.

Congress has expressly directed that NSPS address the emissions of
“any” air pollutant, a term that plainly encompasses CO2.

At a minimum, in directing that NSPS be established for sources that
cause, or contribute significantly to air pollution which may reasonably
be anticipated to endanger public health and welfare, Congress showed
that it meant to require limits on emissions of any pollutants that
cause or contribute to such endangerment. Because cement plants emit CO2
in such amounts that those emissions significantly contribute to “air
pollution which may reasonably be anticipated to endanger public health
or welfare,” EPA is legally required to issue standards of performance
limiting those emissions. EPA cannot rationally assert that cement plant
CO2 emissions do not meet these criteria, and the agency’s refusal to
promulgate standards of performance is therefore unlawful.

EPA’s contention that it can refuse to regulate CO2 emissions on the
basis of interactions with other CAA provisions is impossible to
reconcile with §111, because that section clearly contemplates that EPA
will adopt standards of performance covering pollutants that have not
previously been subject to regulation under the Act.

Cement plants’ emissions of CO2 cause, or contribute significantly to,
air pollution which may reasonably be anticipated to endanger public
health or welfare and significantly contribute to global climate change.

There are existing technologies that can reduce emissions of CO2 from
cement plants. In addition to the suggested technologies, other measures
that would also have CO2 reduction benefits include shifting form high
carbon content fuels, such as coal, to lower carbon content fossil
fuels, such as natural gas.

Section 111(d) of the Act provides that EPA shall require states to
implement and enforce standards of performance for existing sources when
the pollutant at issue is not regulated as a criteria pollutant or
hazardous air pollutant.

EPA must also consult with the US Fish and Wildlife Service and National
Marine Fisheries Service to insure that the final rule is not likely to
jeopardize recently-listed endangered species.

Response: See preamble for the final amendments for the response to this
comment.

2.3	Emission Limits

Comment: Several commenters (65 and 72) state that EPA’s proposed NSPS
for SO2 emissions are inconsistent with §111 and do not reflect the
degree of emission limitation that is achievable through the application
of wet scrubbers, which have already been installed on some kilns and
are the best adequately demonstrated technology. According to the
commenters 65 and 72, the proposed SO2 limit of 1.33 lb/ton of clinker
is so lenient that only a few kilns will actually use scrubbers to
comply. EPA acknowledges that far better SO2 levels can be achieved and
are achieved through the use of wet scrubbers. Specifically, EPA admits
that some kilns are already subject to a BACT limit of 0.2 lb/ton of
clinker. EPA describes that level as one “where moderate and high
sulfur kilns” — as opposed to only a few kilns with extraordinarily
high uncontrolled SO2 levels, “will require the use of a wet scrubber
for SO2 control.” Commenter 72 added that EPA’s desire to shelter
new kilns from having to apply add-on controls is irrelevant under
§111, and EPA’s interpretation of §111 as allowing it to avoid
setting standards reflecting application of the BDT based on that
irrelevant policy consideration is unlawful.

Response: See preamble for the response.

Comment: One commenter (72) states that existing application of wet
scrubbers in the cement industry means wet scrubbers should be
automatically considered BACT for all new U.S. kilns. Section 111(a)(1)
defines a “standard of performance” to mean “a standard for
emissions of air pollutants which reflects the degree of emission
limitation achievable through the application of the best system of
emission reduction which (taking into account the cost of achieving such
reduction and any nonair quality health and environmental impact and
energy requirements) the Administrator determines has been adequately
demonstrated.” (42 U.S.C. §7411(a)(1)). EPA evidently has concluded
that wet scrubbers have been adequately demonstrated considering cost
and the other statutory factors as EPA acknowledges, some kilns already
have installed them. Further, EPA’s proposed NSPS reflect the use of
wet scrubbers, albeit by only a few kilns. Given that wet scrubbers are
the best adequately demonstrated technology, §111 requires EPA to set
NSPS at the level that is “achievable through the application of”
wet scrubbers.

Response: See the preamble for the response.

Comment: One commenter (65) states that, although EPA agrees that it
must set NSPS for NOx, the agency rejects the technology that best
reduces NOx, SCR. EPA states that SCR can reduce NOx emissions by about
80 percent and could be used to attain a standard of 0.5 lb/ton of
clinker. Nonetheless, EPA ultimately proposes to set a much less
protective NOx standard of 1.5 lb/ton of clinker, based on the use of
either “staged combustion in the calciner (SCC),” SNCR, or both. EPA
offers a variety of reasons for rejecting SCR as the BDT, but none of
them have merit. The commenter provides the following comments regarding
EPA’s reasons why SCRs were not chosen as BACT:

EPA admits that SCR has been used at three kilns in Europe, but states
that the kilns are not preheater/precalciner kilns like new US kilns
will be. However, EPA does not say why this distinction makes any
difference nor why future US kilns have to be preheater/precalciner
kilns even if preheater kilns may be cleaner. The CAA requires that NSPS
reflect application of the best demonstrated system of reduction and to
do otherwise to ensure the continued use of a particular production
process would be unlawful. EPA’s failure to explain why the use of a
precalciner precludes the use of SCR is arbitrary. EPA argues that the
ideal location for SCR is at a point where dust levels are high enough
that they may clog the SCR device. But a study on the application of SCR
to cement plants (which EPA neglects to mention) states that the problem
of catalyst fouling has been solved in Europe. EPA itself has stated
that the operational history of SCR installation at a cement plant shows
that it is achieving NOx reductions in a reliable manner and has named
SCR as an available technology for cement kilns in its Best Available
Retrofit Technology (BART) analysis. Reports from industry and
independent contractors make the same point. EPA’s claims about
“potential technical difficulties” are at odds with all of this
information.

According to the commenter, EPA cites cost effectiveness and the
uncertainty of the costs estimates as reasons for rejecting SCR. The
commenter states that EPA’s views about cost-effectiveness are
irrelevant and unlawful under §111, which requires standards to reflect
the degree of limitation that is “achievable” through the
application of the BDT, not the degree of limitation that “EPA
considers cost-effective.” EPA’s cost-effectiveness arguments are
arbitrary as SCR reduces not only NOx but also volatile organic
compounds, dioxins and furans, ammonia, and mercury. If cost
effectiveness is relevant, the true cost-effectiveness of SCR would have
to reflect reductions of all these pollutants and—at a minimum—VOCs,
for which EPA has a statutory obligation to set NSPS. The commenter
states that EPA’s consideration of SCR’s cost-effectiveness only
with respect to NOx and not the other pollutants that SCR controls is at
odds with the agency’s stated intent to use a multi-pollutant and
sector-based approach to setting standards. Finally, EPA’s alleged
“uncertainty” about costs does not justify its rejection of SCR. The
uncertainties all relate to technical issues that have been resolved.
For EPA to rely on such uncertainty despite record evidence showing it
to be unfounded is arbitrary. EPA may not reject a system by claiming
that it has not bothered to fully investigate it, especially a system
such as SCR that is already in use and recognized as reliable and
effective.

Finally, EPA attempts to rely on alleged “adverse non-air and energy
implications” to reject SCR. The only energy concerns EPA cites,
however, relate to using SCR in a low dust environment where (EPA
claims) the exhaust gas would have to be reheated. As EPA acknowledges,
that issue does not exist if the SCR unit is placed upstream where the
exhaust gas is already the ideal temperature and the dust issues
associated with such placement have been addressed and solved. The only
non-air impact EPA mentions is the disposal of used catalysts. Such
disposal issues always arise from the use of air pollution control
issues. EPA does not explain why catalyst disposal outweighs the air
pollution benefits that would result from SCR.

Response: See preamble for response.

Comment: Commenter 64 believes that the best approach is for EPA not to
amend the NSPS to include NOx limits. If EPA indeed intends for the NSPS
NOx limits only to apply to new cement plants or those that have
undergone a redesign to use a preheater/precalciner system, then those
NSPS limits will be applied to a new unit or capital project that will
require federal and/or state permitting. It may also be subject to SIP
limitations, visibility protection rules, other state requirements, and
so forth. The site-specific considerations that go into such
determinations are well-established and are much better able to address
the variety of variables affecting NOx emission limit achievability at
cement plants. Relying on other applicable requirements rather than
developing revised NSPS for NOx also assures that NOx limits for new and
reconstructed plants are based on evolving information and technology,
not set in stone until the next rulemaking like NSPS.

The commenter states that EPA is not under any obligation to include NOx
limits in the revised NSPS. The decision of what pollutants to regulate,
and indeed whether to revise the NSPS at all, is discretionary.
Obviously, EPA has never regulated NOx emissions through the NSPS from
cement plants in the past, and even now EPA does not include limitations
in the NSPS for many fuel-burning sources, including some types of
boilers. In other cases, EPA has recognized that NSPS need not address
all concerns and has taken into account that other requirements will
apply to new or modified sources under federal and state air pollution
laws and regulations, resulting in other or additional control
requirements.

Response: EPA disagrees that the Agency’s decision as to whether to
establish a NOx limit in this NSPS revision is dictated by the lack of
any NOx limits in the existing NSPS. The absence of NOx limits in the
NSPS previously was due to the lack of a demonstrated add-on control
technology applied to cement kilns during EPA’s last review of the
NSPS in 1988. Beginning in the 1990’s, SNCR systems have been
considered and installed on numerous cement kilns in the U.S.
Furthermore, NOx is emitted in large amounts by cement kilns and may be
controlled cost-effectively by a number of means, including SNCR. EPA is
acting well within its discretion, and in keeping with the goals and
policies underlying section 111, in establishing standards for NOx as
part of this revision.

2.4	Pollutants not Included (VOC, PM2.5)

Comment: Several commenters (65 and 72) stated that it is well
established that PM2.5 endangers public health and that under
§111(a)(1), EPA must set NSPS for PM2.5 that reflect the degree of
emission reduction that is achievable through application of the
“best” system of emission control that is adequately demonstrated.

Because the CAA requires emission standards for PM2.5, the agency’s
failure to set such standards is unlawful. EPA discusses the amount of
PM2.5 emissions that its total PM standard would reduce but does not
claim that fabric filters are the best demonstrated system of control
for PM2.5. Nor would any such claim be credible, in the commenter’s
opinion. Fabric filters do not remove the condensable portion of PM
emissions, which is in gaseous form at the stack but condenses into
liquid or solid form within a few seconds of leaving the stack. EPA has
recognized that condensable PM is controlled not by fabric filters but
by wet FGD, wet ESP and alkali injection. EPA states that it “supports
reducing condensable PM emissions,” but does not know whether cement
kilns are a significant source of condensable PM although they are aware
that cement kilns emit enormous amounts of PM. Studies show that the
condensable portion of PM emissions from coal-fired power plants is
50-75 percent. Data available to EPA show that cement kilns’
condensable PM emissions account for a significant portion of their
total PM emissions. For example, Titan Cement’s North Carolina kiln
reports that over 40 percent of its PM emissions are condensable PM. The
CALPUFF model for PM speciation indicates that condensable PM makes up
86 percent of the total PM emissions from a dry kiln with a fabric
filter — i.e., from the kilns that will be governed by the NSPS.

Response: EPA has insufficient data on condensable PM data to establish
limits at this time. EPA notes that under the portion of fine PM that is
attributable to SO2 emissions will be reduced as a result of wet
scrubbers that are installed to comply with the new limits for SO2.
Also, the increased use of membrane filters to comply with the revised
PM standard will reduce PM fine emissions in comparison to standard
woven filters. In addition, in EPA’s revised NESHAP, both existing and
new kilns are expected to use wet scrubbers in order to comply with the
limits for HCl as well as mercury, and in some cases with the revised
limits for THC in the cases where the sources use a regenerative thermal
oxidizer (RTO) because a wet scrubber must precede the RTO to prevent
the fouling of the RTO interior mechanism.

Comment: One commenter (72) states that the fuels and raw materials used
in cement clinker production can result in the emissions of hydrocarbon
pollutants, also known as volatile organic compounds. Volatile organic
compound emissions contribute to the production of ground-level ozone
and some VOC’s are highly toxic. Citing EPA information, the commenter
states that cement plants throughout the country report significant
quantities of hydrocarbon HAP emissions. NSPS implement CAA section
111(b) and are issued for categories of sources which EPA has listed
because they cause, or contribute significantly to air pollution which
may reasonably be anticipated to endanger public health or welfare. The
primary purpose of the NSPS is to attain and maintain ambient air
quality by ensuring that the best demonstrated emission control
technologies are installed as industrial infrastructure is modernized.

Response: Under the NESHAP for portland cement manufacturing plants, all
new kilns are subject to a THC emissions limit of 24 parts per million
volume (ppmv), which would include most VOC’s. EPA believes that it
has adequately addressed VOC limits and that no additional regulation of
VOC is warranted. (Incidentally, the purpose of section 111 new source
standards is to protect and enhance the Nation’s air quality, not just
maintain it. Asarco v. EPA, 578 F. 2d at 327 (D.C. Cir. 1978)).

2.5	General

Comment: One commenter (73) agrees with EPA that BACT determinations may
consider site specific factors, but the commenter states that a BDT
determination must account for factors that may have affected a
site-specific BACT determination but may not be applicable to the
industry as a whole. The commenter states that as required
under§111(a)(1) and was made clear in Nat’l Lime Ass’n v. EPA, 627
F.2d 416, (D.C. Cir. 1980), an achievable standard is one that can be
routinely satisfied under the reasonable worst–case conditions that
can be expected within the industry or source category as a whole. The
commenter states that EPA must rely upon data that accounts for
variability within the industry as a whole and where test data is relied
upon, EPA must have a reasonable basis for believing that the available
data is adequately representative of the industry as a whole (See
Portland Cement Ass’n v. Ruckelshaus, 486 F.2d 375 (D.C. Cir. 1973);
Lignite Energy Council v. EPA, 198 F. 3d 930 (D.C. Cir. 1999)).
According to the commenter, EPA failed to satisfy the requirements of
§111(a)(1) in making BDT determinations using limited data and
extrapolating to establish a standard which EPA speculates can be
achieved on a national basis. According to the commenter, EPA has not
considered adequately the significant factors including
regional/site-specific variations in raw mix which affect the fuel
inputs required to manufacture cement (burnability in EPA’s lexicon),
variations in fuels employed which affect NOx emissions per ton of
clinker produced, and types of cement produced which affect the required
heat input and intensity per ton of clinker produced. Moreover, EPA has
not taken into proper consideration specific design variations that
could or must be employed to assure product quality (alkaline by-pass)
and design variations intended to reduce the energy required to produce
a ton of clinker (clinker cooler ducting to the raw mill). The commenter
states that using this inverted approach, EPA has concluded that
application of BDT supports the proposed NSPS standards for NOx and PM
which exceed current BACT determinations. The commenter states that NSPS
standards should constitute the BACT floor setting, in effect, the
lowest common denominator which current control technology should be
able to achieve on an industry-wide or source category-wide basis. BACT
determinations should then afford individual permitting authorities, on
a case-by-case basis, the ability to establish emission limitations more
stringent than the industry-wide denominator. This is not to say that
BDT, like BACT, cannot be technology forcing. However, when EPA proposes
to adopt as BDT emission limitations more stringent than current BACT,
it must support its decision with sound data and analysis and, according
to the commenter, EPA has not done this.

Response: These general comments are addressed below along with more
specific comments on the NOx and PM limits. However, if the commenter is
arguing that all new sources must be able to achieve a promulgated NSPS,
this is not correct, since that would negate the whole notion of use of
Best Demonstrated Technology. The commenter is correct that EPA must
make a reasoned demonstration that sources utilizing the technology
which is the basis of BDT should meet the standard, and that this
requires EPA to fully assess potential variability and account for it in
the standard. EPA believes it has done so here. For example, for NOx, we
document that existing sources with particularly hard-to-burn inputs are
nonetheless achieving the promulgated limit using SNCR (along with
appropriate baseline control measures). We also explain how both our
assumed baseline for application of end-of-stack controls, and our
assumptions as to emission reductions achievable with (end-of-stack)
SNCR are relatively conservative in order to account for potential
variability.

Comment: One commenter (57) states that proposed sections 60.62(a)(3),
60.62(a)(4)(i) and 60.64(c) mention a 30-day rolling value for NOx and
SO2. However, the rule language does not clearly indicate whether the
period is 30 calendar days or 30 operating days. Section 60.63(l)(1)
mentions “kiln operating days” and 60.63(n)(3) mentions “boiler
operating day.” This suggests that EPA intends the 30-day rolling
period to be 30 operating days, not calendar days. The rule text needs
to clarify EPA’s intent.

Response: The commenter is correct. The 30-day rolling average applies
to operating days. The rule has been clarified.

Comment: One commenter (57) states that assuming that EPA intends to use
operating days; the rule needs to define a “kiln operating day.” EPA
may want to use the boiler operating day definition from 60.41Da.

Response: The rule has been clarified to describe an operating day.

3	Applicability

3.1	Modified Kilns

Comment: Several commenters (61, 64, 73, 83) do not believe that EPA has
sufficient data to support application of the NOx and SO2 emissions
limits to modified wet process kilns which are based on data for new
PH/PC kilns equipped with SNCR and scrubbers. Commenter 61 has been
unable to find data to support an appropriate percentage reduction that
could be attained from installing SNCR on a wet process kiln. According
to the commenter, EPA indicated that older kilns are typically replaced
with new PH/PC kilns rather than being modified or reconstructed.
Commenter 73 believes that EPA erred in its assumption that all
modifications would result in older kilns (including older-design PH/PC)
being replaced with modern PH/PC technology kilns and that EPA did not
evaluate any emission data from existing kilns other than PH/PC kilns;
however, to establish standards applicable to modifications, EPA must
evaluate what might be achievable by the universe of existing kilns
which might undergo physical changes or changes in method of operation
resulting in a “modification” within the meaning of 40 CFR 60.2.
Commenter 61 further stated that the EPA identified two instances of
kilns modified where the proposed limits would apply but believes the
kilns were actually reconstructed in ways which it may be appropriate to
require the reconstructed source to meet the limits for new sources.
Commenter 61 stated that EPA should develop separate NOx and SO2
standards applicable to modified wet kilns and modified long dry kilns.

Commenter 73 states that modern PH/PC kiln technology is capable of
achieving substantially lower uncontrolled NOx and SO2 emission rates
than older kiln technology. For NOx, this is due to staging combustion
and burning a significant amount of fuel in the precalciner, which
generates little or no thermal NOx. For SO2, greater trapping of sulfur
in the clinker is possible through oxidization in the preheater and
routing of gases from the kiln and precalciner to an in-line raw mill.
The commenter states that EPA needs to assess the range of uncontrolled
emissions for each type of kiln configurations and evaluate the
effectiveness, cost and other statutory factors relevant to available
retro-fit control technology for each kiln type and possibly create
subcategories for the different kiln types

One commenter (64) states that changes such as replacement of an
induced-draft fan with one of greater capacity can trigger NSPS and that
an increase in production rate of any amount can trigger NSPS if it
requires a capital expenditure and that such changes would not provide
the opportunity to incorporate process design elements that would allow
the kiln to meet the newly proposed limits or would add costs and delays
to add such process designs that far exceed the change that triggered
the NSPS “modification” provision. This interpretation, according to
the commenter, would create disincentives for efforts to improve energy
efficiency at cement plants if minor adjustments to the process would
trigger new, more stringent emission limits, which could result in
substantial outlays of capital and operating costs as well as delays
associated with the designing, purchasing, and installing new pollution
control equipment to meet the more stringent emission limitations. The
commenter states that because EPA assumed that only new or reconstructed
kilns would be preheater/precalciner designs, their analysis of costs
and economic impacts is faulty. The commenter provided estimates of the
costs that may be incurred as a result of modification-triggered
retrofits at an existing facility. The commenter states that EPA could
also create a separate subcategory for plants that have not yet been
modified to use the newer preheater/precalciner technology and that
modifications at such plants would only be subject to the current PM
NSPS limit of 0.3 lb/ton of feed. This commenter states that EPA has
applied different NSPS limits to facilities with different process
designs to distinguish among classes, types and sizes within categories
of new sources for the purpose of establishing standards

One commenter (73) states that AP-42 lists uncontrolled emission factors
for wet process, long-dry, preheater, and older design PH/PC kilns of
7.4, 6.0, 4.8, and 4.2 pounds of NOx per ton of clinker produced,
respectively compared to an uncontrolled emission rate for modern PH/PC
process kilns as estimated by EPA to range between 2.5 and 3.0 pounds of
NOx per ton of clinker. Commenter 73 operates seven wet process kilns in
the US with annual uncontrolled emission rates ranging between 6.7 and
14.1 pounds of NOx per ton of clinker and seven long-dry process kilns
in the US with annual uncontrolled emission rates ranging between 5.3
and 10.9 pounds of NOx per ton of clinker. Achieving the proposed NOx
limit (based on applying SNCR to PH/PC kilns) with modified older
technology kilns will not always be possible due to the inherently
higher uncontrolled NOx rate. SNCR has not been demonstrated to achieve
this level of reduction on wet process kilns.

One commenter (83) states that the assumption of maximum NOx emissions
of 3.0 lb/ton of clinker and a 50 percent reduction using SNCR are not
appropriate for exiting kilns. The commenter points to EPA’s
Alternative Control Techniques Document which shows the performance of
the different kiln types (that is wet, long dry, preheater, and
preheater/precalciner) can be well above 3.0 lb/ton of clinker. The
commenter supplied data in the form of a chart showing the performance
of SNCR at several of their plants. They used the chart to show that
SNCR often achieves less than a 50 percent NOx removal rate. According
to the commenter, this is significant because if an existing kiln
triggers PSD as a result of increased annual emissions, they must meet
an emission limit achievable through the installation of BACT. The
commenter states that the CAA requires that BACT cannot be less
stringent than emissions allowed by any applicable standard established
pursuant to section 111. The commenter states that even if a
modification of an existing kiln does not trigger the NSPS, the final
NSPS is important to existing kilns as it will establish BACT for all
existing kilns.

Response: At proposal we had one set of emission limits for PM, SO2 and
NOx that were applicable to all new, reconstructed, and modified kilns.
Commenters expressed concerns of the ability of a modified kiln to meet
the same limits as a newly constructed kiln (a so-called greenfield new
source).EPA intends that the revised rule apply to new, modified or
reconstructed kilns that are PH/PC kilns. As discussed in the proposed
rule, all kilns built since 2000 have been of the PH/PC design and the
industry confirmed that any new kiln would be of the PH/PC design.
Typically, older kilns are replaced with new PH/PC kilns which allows
for increased capacity and more energy efficient operation. We did
identify two instances in which a dry kiln and wet kiln were
substantially modified rather than demolished and replaced with new
kilns. Because these were the only two instances identified since 1990,
we do not expect such modifications to be common. In both cases, the
kilns as modified included a preheater and precalciner which were b
expected to be able to comply with the revised limits. In this final
rule we are still including modified kilns as an affected source. If we
were to exempt modified kilns, then such sources would be free to
increase emissions without application of BDT. This would undermine the
basis of section 111 standards, where Congress wanted to assure that BDT
was applied to modified sources qualifying as “new”. Commenters had
also claimed that other regulatory programs, most notably new source
review, would result in a site specific BACT determination if emissions
increased. Though we are always mindful of the interrelationship of
different EPA regulatory programs and their effects, we do not see this
as sufficient reason to exempt modified kilns from the NSPS.

For a modification to cause a kiln to become subject the NSPS, the
modification must result in an increase of the hourly emission rate of
the pollutants subject to the regulation. Furthermore, major sources
undergoing a modification may trigger New Source Review (NSR) and the
requisite RACT, BACT or LAER review. However, we do not think that it is
likely that an owner or operator would modify a kiln in such a way as to
cause it to be subject to the revised NSPS or trigger NSR. It is more
likely that if a modification would otherwise result in an increase in
hourly emission rates, the owner or operator would take necessary
measures, either install the necessary add-on controls or make process
adjustments to avoid making itself subject to an NSR review as well as
subject to the new NSPS limits. The PM and SO2 limits are based on
control technologies that can be applied to any kiln type and achieve
the same control levels that would be expected with a new kiln. So we
see no issue here. Furthermore, in our analysis of the impacts of the
final NESHAP, we determined that in order to meet the final limits for
HCl, nearly all kilns would require the use of wet scrubbers. As a
result of controls for HCl, emissions of SO2 will be lowered as well as
HCl emissions. In such cases, we expect that the kilns will be able to
comply with the limits for SO2. For kilns that are near the limit,
process changes such as the burning of low sulfur coal, as already
required in some state permits, may help to ensure compliance with the
final SO2 limits.

EPA did not intend that the revised standard apply to older wet or dry
kilns undergoing minor modifications, unless they are substantially
modified to the extent described above. We understand that it would not
be reasonable to expect in most cases for older wet and dry kilns to
comply with the new limits, especially the limits for NOx. These kilns
require higher temperatures and longer residence time to dry and calcine
the feed resulting in greater production of NOx in comparison to PH/PC
kilns. In the case of NOx, once we had determined that modified kilns
would be an affected source, we then determined if we should set a
different NOx emissions limit. However, we believe it is environmentally
most advantageous to retain the 1.5 lb/ton clinker limit for modified
kilns. We note that there are kilns of older design that meet levels
below 1.5 lb/ton clinker, and in some cases below 1.0 lb/ton clinker,
with SNCR control. So modified kilns would not necessarily be unable to
meet the 1.5 lb.ton clinker limit. Sources that determine the 1.5 lb/ton
limit is not achievable without control still have the option of adding
NOx control and avoiding the triggering of the modification provision
and PSD for NOx. The NOx control available to cement kilns, in addition
to SNCR, are conversion to indirect firing, mid-kiln fuel injection,
mid-kiln air injection, and substitution of steel slag for some
limestone. Given these available controls, we believe it would be
extremely unlikely that a source that determines the 1.5 lb/ton limit is
not achievable would be unable to apply some type of NOx control that
would avoids triggering the modification or PSD provisions.

Comment: One commenter (73) opposes the application of the proposed SO2
standard to modified kilns. The commenter states that SO2 is primarily a
function of the form and concentration of sulfur present in the
limestone utilized by a cement plant. Older kiln technologies are less
efficient at trapping SO2 in the clinker than modern PH/PC designs. Only
modern PH/PC kilns with extremely high limestone sulfur concentrations
will require extensive controls to meet the proposed NSPS limit.
However, for a majority of the older technology kilns, the only control
option that can assure meeting the proposed NSPS limit of 1.33 pounds
SO2 per ton of clinker produced is a wet gas scrubber. Retrofit capital
cost to install a wet gas scrubber on a typical wet or long-dry kiln is
in the neighborhood of $15-25 million dollars. For these older
technology kilns, this type of cost is not economically feasible,
particularly for minor modifications that would have very little impact
on overall emissions.

Response: See the previous response.

Comment: One commenter (73) opposes revising the NSPS standard for PM
emissions from modified kilns. All cement kilns operating in the U.S.
utilize PM controls. Two primary types of controls are used: baghouses
and electrostatic precipitators. In deriving the proposed PM NSPS limit,
EPA only looked at baghouses with membrane bags. New or reconstructed
kilns would be designed with modern baghouses that could incorporate
membrane bags. However, existing plants may not have this capability, or
the plant may operate an ESP which may not be capable of achieving the
same level of PM reduction as a new modern baghouse with membrane bags.

Response: See the previous response. In addition, under the final
NESHAP, many plants will install activated carbon injection (ACI)
systems for the control of mercury, organic HAP and THC emissions.
Because ACI systems will be installed after existing PM devices, they
will use a polishing baghouse to remove the carbon from the exhaust gas
stream. As a result, the owner or operator of a kiln controlled with an
ESP will in most cases be able to meet the limits for PM because of the
additional downstream PM control device.

4	Emission Limits

4.1	General

Comment: One commenter (74) stated that once the U.S. EPA sets new
emission limits, local agencies may dictate emission limits that will be
even lower on specific projects. The commenter cites examples of this
and recommended that the new NSPS limits be stringent and achievable for
100 percent of cement plants nationwide. The commenter states that,
consequently, all plants will have achievable limits on a national basis
and the ability to meet even lower emissions due to local requirements
that are evaluated on a case-by-case basis.

Response: The purpose of the NSPS program is to ensure that the best
demonstrated emissions control technologies are installed as industrial
infrastructure is modernized. Such plants are to meet standards
reflecting Best Demonstrated Technology. A standard that could be met by
100 percent of the industry (a priori) is highly unlikely to reflect
BDT. EPA is aware that cement plants vary from one another in their raw
materials, fuel and cement product and that the details of the
combustion and pollution control technologies required to meet these new
limits may require site-specific adjustment. In setting the new limits
for NOx, SO2 and PM, EPA understands that some new, reconstructed or
modified kilns will find it a challenge to meet the new limits while
others will not. EPA is also aware that state and local agencies can set
limits more stringent than those in the revised NSPS and expects that
they will as local circumstances dictate, especially for efforts to
attain various of the applicable National Ambient Air Quality Standards.

4.2	Format

Comment: Commenters (68, 71) support EPA’s proposed limits in lb/ton
of clinker over the previous lb-per-ton of dry feed limit as the new
limits avoid rewarding a source for becoming less efficient (i.e.,
requiring more feed to produce a unit of product).

Response: EPA notes the commenter’s support.

4.3	NOx

Comment: Several commenters (59, 60, 63, 68, 70, 71, 72) approve of the
proposed limits for NOx or believe more stringent limits are
appropriate. One commenter (59) states that the proposed standard is
unjustifiably high, and will allow for greater NOx emissions than can be
achieved with the installation of off-the-shelf pollution control
technology. The commenter recommends that the new performance standard
require emissions no greater than 0.5 lb NOx/ton clinker and states that
SCR is an effective and proven technology to reduce NOx emissions from
cement kilns and can reduce NOx emissions from cement kilns by greater
than 90 percent, consistent with what has been observed with SCR in
other industries. According to the commenter, SCR can achieve this
performance with cost effectiveness of approximately $1,500-$3,800/ton
NOx, easily within regulatory cost thresholds for many NOx control
programs. Regarding concerns over dust and plugging, the commenter cites
three recent installations of SCR on cement kilns that show that SCR
vendors can properly design and install units which manage the dust and
successfully operate for many years. The commenter stated that numerous
SCR companies believe that they can design and supply SCR systems for
NOx control at cement plants where they will have to guarantee
performance levels in legal contracts, and thus, they would be at
significant financial risk to advertise and sell an SCR system that was
actually going to fail. The effectiveness of the technology to reduce
NOx and other pollutant emissions from cement kilns, as demonstrated by
the SCR installations on cement kilns in Europe and the numerous SCR
installations on other heavy industries like coal-fired power plants and
waste incinerators is supported by the marketing, technical assessments,
and reports prepared by numerous experts on this subject, including:
three (3) cement companies, five (5) SCR manufacturers, an independent
blue ribbon panel, the U.S. EPA (twice), and the European IPPC.

Commenter 68 believes that EPA’s proposed NOx emission limit of 1.5
lb/ton clinker seriously underestimates the reductions that are
achievable with SCR technology and recommends that SCR be identified as
BDT for this sector and is “the regulated future” for cement kilns.
The commenter states that the agency has noted that hybrid combinations
of SNCR and SCR could be used in new cement kilns to achieve greater
reductions than would be possible with SNCR alone. Like SCR, we have no
evidence of this combination being applied here or elsewhere.  SCR is
also named by EPA as available technology for cement kilns in the
Regulatory Impact Analysis for the Final Clean Air Visibility Rule or
the Guidelines for Best Available Retrofit Technology (BART)
Determinations under the Regional Haze Regulations. In fact, as far back
as 1999, EPA included SCR in a list of control technologies available
for both dry and wet cement manufacturing processes, as did a Pechan &
Associates Report prepared for EPA’s Office of Air Quality Planning
and Standards in September 2005. Therefore, SCR technology for the
cement manufacturing sector has been considered feasible technology by
EPA for some time. While the commenter applauds EPA’s decision to add
NOx to the NSPS for cement kilns, this commenter recommends that EPA
adopt SCR as BDT stating that NOx contributes significantly to ozone
formation, which poses potential health risks to the more than
100 million individuals who live in areas that failed to attain the
health-based primary standard for ozone. The NOx contributions of the
portland cement sector must, therefore, be viewed against this dismaying
context of the increasing impacts of ozone pollution on human health and
the environment.

One commenter (60) states that the NOx emission limit should be lowered
from 1.5 lb of NOx/ton of clinker on a 30 day rolling averages to 1.0
lb/ton of clinker on a 24 hour rolling average for new PH/PC kilns and
a limit added of 2.0 lb/ ton of clinker on a 24-hour rolling average if
reconstruction or modification of the kiln commences after June 16,
2008, and the final configuration is a long wet kiln or a long dry kiln.
The commenter states that the recommendations regarding PH and PH/C
kilns should apply equally to projects at greenfield sites and to
projects at brownfield sites stating that many of the advances in NOx
control in the U.S. and Europe have been made at brownfield sites
whether they have involved new kilns or reconstruction or modification
of existing kilns.

To support the commenter’s recommended limits for NOx, the commenter
provided the following information and included several supporting
documents as attachments to the comments:

A long-term value of 1.46 pounds per ton (lb/ton) of NOx clinker was
achieved with no add-on control equipment when not accounting for slag
use and 1.38 lb/ton when accounting for slag use at TXI Kiln 5 (a PH/C
kiln) in Midlothian, Texas.

A long-term value of 1.98 lb/ton was achieved with no add-on control
equipment at Cemex Sta. Cruz (a PC/H kiln) in Davenport, California. The
project involved an improvement to an existing calciner (commissioned in
1997) on an existing kiln to comply with an existing NOx limitation.

Titan America (a PH/C kiln) in Medley Florida and Giant Cement in South
Carolina where average values of 1.62 and 1.88 lb NOx/ton were
documented for new kilns with no add-on control equipment at brownfield
sites.

The results from the existing SCANCEM (an affiliate of Lehigh) Skövde
PH kiln where emissions were reduced from 4.4 lb NOx/ton (1995) by
installation of a SNCR system and which achieved 0.72 lb/ton in 2005.

The results from the existing SCANCEM Slite PH/C kilns where emissions
were reduced from 4.0 lb NOx/ton (1995) by installation of an SNCR
system and which achieved 1.01 lb/ton in 2005.

The results from the existing Radici Cementeria di Monselice PH kiln
where emission reductions to values as low as 0.20 lb NOx/ton were
demonstrated by installation of a SCR system. The supplier guaranteed
reduction of 90 percent and realized reductions as high as 97 percent.

Commenter 60 states that based on the foregoing, it is clear that
reductions on the order of 75 percent are achieved by well-designed SNCR
systems and 90 percent by SCR. Given that a new kiln can be designed
such that emissions can be controlled to values between 1.5 and 2 lb/ton
before add-on control, it is clear that 1 lb/ton is easily achievable by
SNCR. Given a kiln with less sophisticated design or particularly
difficult raw materials achieving 3 to 5 lb/ton, it is clear that SNCR
or SCR or a combination of the two can readily reduce emissions to
values much less than 1 lb/ton. The commenter states that the proposed
averaging time of 30 days is a tremendous concession to the industry.
The availability of reagent injection makes it easier to achieve the
proposed standard on a 24-hour basis. The lowest permit limit for a
project under construction in the United States applies to the Drake
Cement in Arizona. The value is equivalent to 1.14 lb/ton on a 24-hour
basis. A contract was awarded to F.L. Smidth who developed the calciner
that achieves 2 lb/ton or less at TXI, Titan and Cemex as discussed
above. The limit will be readily achievable using an SNCR system. The
commenter provides additional details on the history and performance of
NOx process controls (such as SCC) and add-on controls (such as SNCR) in
the US and elsewhere.

One commenter (60) states that because long wet and long dry kilns use
much more energy to make a ton of clinker, a higher NOx limit may be
acceptable for these kilns. Commenter 60 agrees with EPA’s assumption
that new projects triggering the NSPS will actually result in a PH/C
kiln. A project that might trigger a prevention of significant
deterioration (PSD) review at a long kiln will probably incorporate
emissions control measures to avoid PSD and a BACT determination for NOx
and SO2. The measures to avoid PSD will also likely avoid the short-term
emissions increases that would otherwise trigger the NSPS. Finally, with
respect to the reconstruction provisions, it is not likely that a
company will actually invest 50 percent of the value of an existing long
kiln without taking the opportunity to make it much more energy
efficient through conversion to a PH/C kiln. The commenter states that a
separate standard for long kilns will avoid the unnecessary relaxation
of the limits applicable to PH and PH/C kilns. The commenter listed the
following NOx reduction technologies that have been demonstrated for
long kilns and submitted supporting documentation as attachments to the
comment:

Conversion from direct to indirect firing in conjunction with the
installation of a multi-channel (Low NOx) burner;

Mid kiln fuel injection (including tires);

Near mid-kiln pressurized air injection;

SNCR at long kilns; and

Combination of SNCR with air injection.

One commenter (63) described the advances in technology for controlling
NOx emissions, especially SNCR and SCR, from portland cement plants, and
requests EPA to fully consider the technological improvements and their
applications when establishing NOx emission limits for the portland
cement manufacturing industry. The commenter states that EPA continues
to play a crucial role in encouraging innovation and in mobilizing
supply chains to deliver technologies that improve our air quality and
environment including the continued tightening of emission limits. This
encourages the industries such as the cement industry to work closely
with equipment and component suppliers to ensure significant reductions
in emissions in a timely and economical manner. The commenter states
that with the improved processes that lower uncontrolled NOx emissions
and with the addition of SCR, NOx limits of 0.25-0.5 lb NOx /ton clinker
are achievable.

One commenter (70) supports the proposed level for new, modified and
reconstructed kilns of 1.50 lb/ton of clinker for NOx. Facilities can
meet the 1.50 lb/ton of clinker for NOx, with SNCR alone or with SCR
(either as a supplement or as an alternative to SNCR).

One commenter (71) states that if new or modified systems would likely
use the preheater/precalciner configuration, then what is achievable
must be looked at and then apply the effect of the controls. If this
approach is followed, the appropriate NOx emission limit should be in
the range of 1.14 lb/ton of clinker. According to commenter 71, the
traditional long dry cement kilns can attain a NOx emission level of
2.73 lb/ton of clinker without utilizing SNCR control technology. Based
on a SNCR control efficiency of 50 percent, a NOx emission level of 1.3
lb/ton of clinker is achievable. As a result, cement kilns with SNCR
control technology can achieve a NOx emission level between 1.14 and
1.3 lb/ton of clinker. However, this commenter believes that the NOx
emission level from cement kilns can be further reduced by utilizing SCR
control technology. Commenter 71 states that EPA dismisses the SCR
technology used in Europe for the most trivial of reasons. Commenter 71
concedes that some mechanical problems were experienced in the early
stages with plugging but these problems were resolved and the system
remained in service for four years at the Solnhofen facility in Germany.
According to the commenter, waste disposal should not be an issue
because the spent catalyst could be added to the process as a source of
alumina. Commenter 71 previously conducted a Best Available Retrofit
Control Technology (BARCT) assessment for a cement plant in our area and
recommended SCR as the BARCT for this facility.

One commenter (72) states that the NSPS emission rate for NOx from
cement plants should be lowered to 0.5 lb/ton of clinker on a 24 hour
rolling average because of the ability of current plant designs to
achieve very low rates of NOx emissions without the addition of add-on
pollution controls. Currently available add-on controls can reduce NOx
emission levels below the proposed 1.5 lbs of NOx per ton of clinker.
There is a considerable operational experience with SNCR that shows
it’s capable of reducing NOx emissions to 1 lb or less/ton of clinker
when combined with a modern-designed kiln. SCR has been demonstrated in
the utility industry and Europe and can further reduce emissions.

Response: See the preamble for the response.

Comment: Several commenters (64, 73, 74, 75, 76, 77, 78) commented on
the difficulty of consistently achieving the NOx limit of 1.5 lb/ton
clinker limit over time and at all new kiln locations and favored a
somewhat higher limit or no limit. They state that it is important to
note that consistent, long term compliance with this proposed limit may
be difficult to achieve and there will be instances where compliance may
not be possible at all. Different factors can influence NOx emissions
such as:

Fuel type/quality - lower volatility solid fuels such as petcoke produce
higher NOx emissions. Also, any problems with fuel quality as delivered
to the plant can have a negative impact on NOx emissions;

Raw mix burnability - harder burnability will give higher NOx emissions.
Burnability is dependent on the raw mix chemistry, fineness, and
chemical deviation (impacted by homogeneity and operation of the quarry,
which can vary over extended periods of time);

Kiln bypass system - The size of the bypass for a given plant (if
needed), and consequently the bypass emissions, depends on the chemistry
of the raw mix and fuel(s) and the product standards that must be
maintained to comply with regulations;

Size/type of the preheater - new in-line calciners will normally give
the lowest NOx emissions; however, in cases where the type of fuel(s)
used dictates the need for a separate calciner (such as may be applied
to utilize waste materials), NOx emissions will be higher. In addition,
sometimes a new project will consist of upgrading an existing pyro
system. In many of these cases the layout of the existing equipment is
such that it cannot be modified to perform as well as a brand new
calciner system, and will therefore have higher NOx emissions;

Sub-standard operation and maintenance of the kiln system - this is the
responsibility of the cement producer, but it is also expected that NOx
emissions will increase slightly over a typical campaign between annual
maintenance stoppages due to normal “wear and tear” of the system;
and

SNCR efficiency and slippage - the ability of an SNCR system to reduce
NOx emissions is not the same for all systems, especially for an
existing pyro system that has been upgraded (due to potential lack of an
optimum injection point) or a very large pyro system (due to lack of
optimum mixing of ammonia and preheater gas).

One commenter (75) states that although the removal efficiency of SNCR
can theoretically be improved by increasing the quantity of ammonia
injection, there is a practical limit to this approach. As ammonia
injection rates increase, the potential formation of a secondary plume
due to “ammonia slip” increases. In addition, sulfur in the raw
materials results in SO2 and SO3 in the exhaust, which decreases the
efficiency of ammonia injection and leads to operational issues such as
solids accumulation and plugging downstream of the SNCR. As the
commenter noted in the permit application for its proposed kiln,
facilities with lower BACT emission limits are also those facilities
with lower sulfur raw materials, notably plants located in Florida,
thereby improving the efficiency of SNCR. Given the baseline NOx
emissions expected at a new plant, Commenter 75 would need a control
level of at least 70 percent to meet the proposed limit of 1.5 lb/ton.
Commenter 75 is not confident that this can be done with SNCR.
Therefore, the commenter recommends that the NOx standard be established
at 1.95 lb/ton, which reflects a level of control achievable with the
use of SNCR by all facilities without introducing the negative effects
associated with pushing for high control levels.

One commenter (76) states that assuming a facility is already operating
with best combustion practices (i.e., indirect fired fuel supply
systems, low primary air burners, etc.) then the burnability of the raw
mix has the greatest single impact on NOx emissions. Statistically
speaking, most preheater precalciner cement kiln plants worldwide emit
an uncontrolled NOx emission of 3.8 to 4.2 lb NOx/ton of clinker. With a
50 percent NOx reduction rate from the application of SNCR technology, a
controlled emission rate of 1.9 to 2.1 lb NOx/ton of clinker could be
expected for most kilns. As such, a 1.95 lb NOx/t clinker limit for all
new kiln applications seems achievable. The issues arise when people
arbitrarily apply the 50 percent reduction potential of SNCR to lower
baseline emission numbers. (i.e., at a 3.2 lb NOx/ton of clinker
uncontrolled emission, SNCR could reduce it to 1.6 lb NOx/ton of
clinker). While this might be true on an isolated case basis, it would
be unwise to approach such a low level for a new NSPS limit for all new
kilns because of the issue of burnability. In some cases it might be
possible to reduce the baseline NOx levels with integrated control
systems, such as Multi-Stage Combustion (MSC) installed on low NOx
calciner system; but here again, the practicality of sustaining stable,
continuous operation while simultaneously reducing the baseline NOx by
10 to 30 percent is very site specific. Commenter 76 believes that a
controlled emission rate of 1.95 lb NOx/ton of clinker can be achieved
by all new kiln applications providing SNCR is used as the principle
measure to control NOx emissions, but excluding that portion of gases
that may be extracted through a bypass system.

One commenter (77) believes that under the worst-cast combinations of
raw materials, fuels and cement specifications and with the application
of SNCR technology, a controlled emission rate of 2.0 lbs of NOx per
ton of cement clinker can be achieved by all new kiln applications.
However, if the kiln must incorporate a bypass for alkalis, chlorides or
sulfur, the NSPS limits must allow for increased NOx emissions on a
plant by plant basis due to the fact that bypass amounts can be anywhere
from 5 percent to 100 percent in size.

One commenter (78) states that very few kilns with alkali bypasses would
have a chance of meeting the proposed limit on a long-term basis. One
commenter (83) requested that EPA clarify whether the NOx limit applies
only to a kiln’s main stack or whether it applies across both the main
and bypass stacks.

One commenter (73) believes that EPA failed to identify and
appropriately consider the variables that affect uncontrolled NOx
emissions from modern preheater/precalciner kilns employing SCC and LNB
on an industry-wide basis. As a consequence, EPA relied upon too limited
a database that did not reflect these variables and then made
assumptions reflecting an incomplete understanding of the range of
variability in uncontrolled NOx that result from them. Commenter 73
recommends that EPA revise its proposed baseline NOx emission standard
from 1.5 to 2.0 lb/ton of clinker, and allow for adjustments of the
standard upward from this value when bypasses are used, unusually hard
burning raw mixes are used, or specific clinker types (such as oil well
clinker) that require non-typical burning methods is being produced.
When bypasses, hard burning mixes and/or clinker specifications require
non-typical operational parameters, an adjustment factor should be
allowed and evaluated on a case-by-case basis. The fact that individual
kilns may be able to achieve a NOx emission rate as proposed by EPA (or
even lower rates) is not determinative of what is an appropriate
standard for the NSPS.

Commenter 73 states that fuel volatility plays a major role in NOx
emission control. The uncontrolled NOx generated in the precalciner
alone can vary by as much as 1.4 g/kg of clinker (2.8 lb/ton clinker)
based on fuel volatility. Commenter 73 states that modern
preheater/precalciner kilns fire approximately 55-65 percent of their
fuel in the precalciner. The nitrogen content in the fuel is the main
factor affecting fuel NOx formation. The fuel NOx produced in the
precalciner is not directly proportional to the nitrogen content of the
fuel. It also depends on the chemical form of the nitrogen in the fuel
and the volatility of the fuel. Typically, fuel nitrogen in coals used
by PH/PC kilns varies between 1.0 and 2.0 percent. This difference can
impact the uncontrolled NOx by as much as 1.5 lb/ton of clinker.

Commenter 73 states that a PH/PC kiln system uses hot gases from the
kiln to both dry and heat the raw materials prior to calcination. The
effectiveness of this system is related to the moisture content of the
raw materials and their ability to absorb heat from the gases. If
additional heat is required to dry or heat the raw materials, gases from
a separate fuel-fired furnace or the clinker cooler are ducted to the
raw mill. As a result, the moisture content of the raw materials
directly influences the NOx emission rates. High moisture materials
require additional energy to dry the materials in the raw mill and/or
preheater. This increased need for energy contributes to the amount of
NOx emitted if the excess energy comes from burning additional fuel.
Some plants may have up to 20-25 percent moisture content in their raw
mix – which results in a 15 to 20 percent increase in the kiln’s
specific heat consumption, as compared to a “standard” raw mix that
contains approximately 5 percent moisture. This additional energy need
results in the combustion of more fuel which ultimately results in more
uncontrolled NOx.

On NOx emissions from alkali bypasses, commenter 73 states that because
the gases within the bypass are not allowed to remain in the optimal
SNCR temperature range, SNCR is not a feasible control option for these
gases. The commenter shows (in graph form in their comments) that for a
certain size kiln, bypassing 25 percent of its kiln gases will have an
incremental increase of approximately 0.42 lb/ton of clinker in the
controlled NOx emission rate.

Commenter 73 states that the three major kiln suppliers require a cement
company to provide detailed information on raw materials (including
moisture content), fuels, and clinker quality specifications prior to
preparing a quotation and specifying emission guarantees. Uncontrolled
30-day average NOx emissions can vary from less than 1.6 to greater than
4.6 lb/ton of clinker. SNCR has been demonstrated to reduce NOx
emissions from cement kilns; however, SNCR has not been used on cement
kilns for an extended period of time. High removal efficiencies such as
those stated in the preamble (i.e., 63 percent at an ammonia-to-NOx
ratio of 1.0) may result in adverse product quality or environmental
impacts that are undesirable. In addition, the use of SNCR on larger
kilns (>2,000,000 ton/yr capacity) may not be as effective due to the
larger calciner duct diameter and the ability for the ammonia-reagent to
mix thoroughly with the combustion gases. Based on limited data, removal
efficiencies of 25-50 percent appear to be achievable without these
adverse impacts. Therefore, Commenter 73 believes that since NSPS is
applicable to all new or reconstructed kilns, a reasonable baseline NSPS
limit taking into account typical operating conditions and limitations
stated above is 2.0 lb/ton of clinker. However, when non-typical
conditions exist (bypass, hard burning mixes, and specific clinkers that
require non-typical burning methods), an adjustment upward from the
baseline value is appropriate and should be made on a case-by-case
basis.

Commenters (64, 73) stated that the proposed NOx limitations are
substantially more stringent than the most stringent NOx limit that
applies to cement plants in Europe, which converts to approximately
2.5 lb/ton of clinker produced although EPA asserts that this should be
considered the “baseline level of control that would occur with no
additional regulatory action. The commenter states that there are
several problems with that analysis: 1) It does not appear that this
conclusion is based on a “statistically sound” analysis, as the
statute requires; 2) If the NSPS were set at 2.5 lbs. [sic] of NOx per
ton of clinker, then all affected facilities would have to meet the
limitation continuously, rather than the “average” performance of
all affected facilities being at or below 2.5 [sic] lb/ton. Therefore,
it would appear from EPA’s rationale that setting an emission standard
of 2.5 [sic] lb/ton would require some facilities, even if they have SCC
and low-NOx burners, to implement additional NOx controls in order to
comply continuously with that standard throughout the life of the
facility.

The commenter states that there may be substantial differences between
the NOx emissions that can be achieved by new, greenfield kilns and what
can be achieved by “reconstructed,” brownfield kilns. NOx emissions
are a function of fuel type and of raw material type. Some raw materials
will require longer residence time in the kiln, and perhaps at higher
temperature and produces more uncontrolled NOx emissions, and therefore
makes meeting a given emission limit more problematic and costly. The
same is true of fuel that has a higher mass of nitrogen per unit of heat
value. Reconstructed cement plants usually will have little or no
control over their raw materials and may have limited control over the
fuel they can use.

The commenter states that EPA also needs to address the achievability of
NOx limitations at cement plants that have bypass stacks or ducts to
control alkalinity because EPA has not presented in the preamble to the
proposed rule any basis for concluding that SNCR is a demonstrated
technology for meeting the proposed for facilities with bypass systems.

Likewise, while EPA acknowledges that burnability may have a significant
influence on NOx emissions, EPA has not explained how these differences
are reflected in its analysis of the BDT and the proposed new NOx
limits. Cement plants with hard-to-burn raw materials face much greater
challenges in meeting a NOx limit and applying SNCR.

Commenter 64 agrees with EPA that SCR has not been demonstrated on
preheater/precalciner kilns and that there are substantial unresolved
issues about the potential for use of SCR at such cement plants.
Commenter 64 also notes that, in addition to the cost which EPA
identified as a disadvantage of a low-dust SCR system, there would be
substantial adverse energy usage and GHG consequences of re-heating the
flue gas for a low-dust SCR system.

Commenter 64 also believes that EPA has not given adequate consideration
to ammonia slip from the use of SCNR. EPA seems to acknowledge that it
does not have data on how ammonia slip will contribute to condensable PM
emissions, and what if anything could be done to mitigate that
contribution. EPA has not conducted a sufficient technical analysis to
support new NOx emission limits that would effectively require use of
SNCR without addressing the ammonia slip issues. Ammonia slip may be a
particular problem when SNCR is applied to particular designs, such as
pyro systems that have been modified or that are particularly large. The
inability of these systems to promote the reaction of ammonia with NOx
also reduces potential control efficiency of SNCR on these systems.

Commenter 64 believes that the best approach is for EPA not to amend the
NSPS to include NOx limits. If EPA nevertheless insists on including NOx
in the revised Subpart F NSPS, then commenter 64 recommends that for
preheater/precalciner kilns (whether constructed at Greenfield or
brownfield sites), a NOx emission floor of 1.95 lb/ton of clinker be
established as the NSPS limit. This limit would then be modified on a
case-by-case basis to account for site-specific factors such as the
presence of a bypass stack/duct or difficult to burn limestone or fuels,
likely resulting in an emission limit in excess of the recommended
floor.

Response: See the preamble for the response.

4.4	SO2

Comment: Several commenters (60, 68, 70, 71, 72) stated that the
proposed limits for SO2were not sufficiently stringent. Commenter (60)
recommends deleting the 90 percent reduction option, revising the limit
for SO2 to 0.5 lb/ton clinker on a 24-hr rolling average if the kiln is
a PH or PH/PC kiln and adding a limit of 1.0 lb/ton clinker on a 24-hr
rolling average if the kiln is a long wet or long dry kiln. Commenter 72
concurs on reducing the limit to 0.5 lb/ton for PH/PC kilns. Commenter
60 states that for PH and PH/C kilns, the limit should apply equally to
projects at greenfield sites and to projects at brownfield sites.
Commenter 60 cites kiln performance at brownfield sites whether they
have involved new kilns or reconstruction or modification of existing
kilns:

Cement plants in Florida emit on the order of 0.10 lb SO2/ton clinker.
Although these kilns have very low-sulfur feed materials, all of them
use coal and rely on the fuel SO2 control that is inherent in the PH and
PH/C designs. The steps include reaction with alkali and incorporation
into the clinker in the burning zone, dry scrubbing with finely divided
lime in the calcination zone and moist limestone scrubbing in the raw
mill.

Commenters 60 and 72 cite the performance of the kilns used by EPA to
establish the proposed limit:

The key kiln (kiln 5 at TXI Midlothian, TX) upon which EPA based the
proposed the SO2 standard of 1.33 lb/ton has actually operated at 0.37
to 0.57 lb/ton.

Commenters 60 and 72 state that raw materials in the Midlothian area are
known for high-sulfur feed materials and the TXI kiln has a wet scrubber
to reduce (non-fuel) SO2 emissions. The limit for Kiln 5 is now
approximately 0.95 lb/ton following a production increase authorized by
the Texas Commission on Environmental Quality (TCEQ). TXI Midlothian
Kiln 5 and two other PH/C kilns (Kilns 1 and 2) operated by Holcim in
the same city are controlled by wet scrubbers. All three have wet
scrubbers yet there is a vast difference in performance between the TXI
Kiln 5 and the Holcim Kilns 1 and 2. The commenter presented data on the
SO2 performance of the 3 scrubber controlled kilns. According to the
commenter, the TXI Kiln 5 can consistently achieve SO2 emissions less
than 0.5 lb/ton if required by a permit limit. The higher SO2 values for
the Holcim kilns (> 4 lb/ton) represent the first year of joint
operation. Thereafter, Holcim Kilns 1 and 2 were operated at levels
between 2 and 3 lb/ton. The commenter states that they can choose to run
one to four pumps providing reductions in SO2 emissions ranging from 51
percent with a single pump in operation to 91 percent with four pumps in
operation.

Commenters 60 and 72 state that the Ash Grove Chanute PH/C kiln in
Kansas achieves less than 0.30 lb SO2/ton despite high sulfur in the raw
materials without even using a wet scrubber. Commenter 60 states that
this performance is attained using important innovations (the F.L.
Smidth DeSOx system and Environcare Micromist Lime system) not yet
assessed by EPA. Attachments provided as part of the comment describes
these technologies. Commenter 60 states that without controls the
proposed Chanute kiln would emit SO2 at the high rate of 12 lb/ton from
raw material sources alone (i.e. exclusive of fuel SO2). According to
Commenter 60, using the described technology, actual emissions from the
Ash Grove Chanute kiln are less than 0.25 lb SO2/ton.

According to commenter 60, the Holcim Siggenthal PH kiln in Switzerland
achieves approximately 0.05 lb SO2/ton using the POLVITEC coke filter
installed in the 1990’s. The POLVITEC system is used with various
concurrent operational practices to control NH3 (from an SNCR system),
SO2, PM and metals. Among several functions, the coke filter captures
the non-fuel SO2 generated in the PH. The coke is subsequently crushed
and then burned with fuel in the main kiln burner. The SO2 from the PH
then behaves like fuel SO2 and is incorporated into the clinker. Further
details are available in an attachment submitted with the comment. The
commenter states that SO2 emissions would be significantly less than
0.10 lb/ton of clinker. According to the commenter, the Siggenthal plant
emits much less SO2 than the average of Holcim cement plants in
Switzerland and clearly less than 0.10 lb SO2/ton.

Commenters 60 and 72 state that the Holcim Untervaz plant Switzerland
achieves between 0.04 and 0.21 lb SO2/ton using a wet scrubber despite,
according to commenter 72, the presence in the limestone of iron
sulfide. Holcim initially installed a dry scrubber at the Untervaz plant
in the late 1980’s. Recent data provided by the commenter indicate
significant reductions in SO2 emissions from since 2002 largely due to
the replacement of the older dry scrubber with a more efficient and
economic wet scrubber.

According to commenter 60, the areas where medium sulfur raw materials
are present can implement programs similar to the Ash Grove installation
without installing large wet scrubbers, dry scrubbers or coke filters.
Finally selective mining of the available raw materials with respect to
sulfur content is an important SO2 control strategy for any new project.
In summary, Commenter 60 recommends an NSPS SO2 limit of 0.50 lb/ton of
clinker on a 24-hour basis for PH and PH/C kilns.

Commenter 60 states that because long wet and long dry kilns use more
energy to make a ton of clinker, a higher SO2 limit may be acceptable.
Commenter 60 agrees with EPA’s assumption that new projects triggering
the NSPS will result in a PH/C kiln. According to the commenter,
projects that might trigger a PSD review at a long wet or long dry kiln
will probably incorporate emissions control measures to avoid PSD and a
BACT determination. The measures to avoid PSD will also likely avoid the
short-term emissions increases that would otherwise trigger the NSPS.
With respect to the reconstruction provisions, the commenter states that
it is not likely that a company will actually invest 50 percent of the
(undepreciated) value of an existing long kiln without taking the
opportunity to make it much more energy efficient through conversion to
a PH/C kiln. Nevertheless, the commenter states that it is advisable to
separate out the (unlikely) long kiln projects that trigger the NSPS
without resulting in PH or PH/C kilns in order to avoid the unnecessary
relaxation of the limits applicable to the much more likely PH and PH/C
kilns. According to the commenter, scrubbers are available for long
kilns just as they are available for PH and PH/C kilns. Other strategies
suggested cited by the commenter include 1)Near mid-kiln pressurized air
injection; and 2) Chains near the entrance of the kiln that can improve
contact between the incoming wet limestone and the SO2-laden exhaust
gases containing both raw material and fuel sulfur.

Commenter 60 states that good SO2 control will make it possible to
employ more aggressive NOx control and that the control of NOx and SO2
will also minimize the formation of ozone and fine PM in the
environment.

Commenters (68, 70, 71) states that State and local experts, who have
had long experience with this industry, believe that the proposed NSPS
limit for SO2 does not reflect what most plants are capable of
achieving. Even taking into account regional variability in the pyritic
sulfur content of the raw materials, this commenters finds that most
cement kilns already achieve lower SO2 emissions than the 1.33 lb/ton
of clinker proposed.

Commenter 70 stated that after addressing raw materials in their most
recent BACT review, SO2 limitations were 0.9 lb/ton of clinker (30-day
average) and 1.6 lb/ton of clinker (24-hr average); considerably lower
than the 1.33 lb/ton of clinker (30-day average) proposed.

Response: See the preamble for the response.

Comment: Several commenters (64, 74, 75) expressed concerns that the
proposed limits for SO2 are too stringent. One commenter (64) recommends
that EPA not include SO2 limitations because EPA recognizes that there
are only “a few locations” where the raw materials contain high
levels of sulfur, and in those few situations state regulations already
impose SO2 emission limitations that require the type of technology EPA
proposes as the basis for the proposed SO2 limitations. The commenter
states that EPA assumes that one out of five new kilns will be sited
where the raw materials are high in sulfur, requiring an SO2 scrubber or
a lime injection system when in fact at existing plants there have only
been a handful of situations where high-sulfur materials have been
determined to justify wet scrubbers. According to the commenter, of
28 BACT determinations for SO2 for cement kilns since 1998 reported in
the RACT/BACT/LAER Clearinghouse (RBLC), only 5 were based on wet
scrubbers, and 1 each specified a dry scrubber or hydrated lime
injection while the majority required no add-on controls because of
low-sulfur raw materials or reliance on the inherent process absorption
of SO2. The commenter states that the preamble information that only
5 kilns out of 178 kilns currently use a wet scrubber indicates that
uncontrolled SO2 emissions are rarely high enough to justify add-on
controls.

The commenter states that EPA acknowledges in the preamble that EPA is
not obligated to promulgate NSPS for every pollutant emitted by sources
in the source category. According to the commenter, the fact that very
few cement kilns have been required to employ add-on controls for SO2 is
evidence that there are few instances where cement kilns are
contributing to SO2 NAAQS nonattainment, so there is no need for an SO2
NSPS to address ambient air quality problems.

Commenter 64 states that allowing state and site-specific requirements
address SO2 at plants with high-sulfur raw materials would address
weaknesses in EPA’s proposed SO2 standards. For example, although EPA
assumes that the proposed SO2 standards will require add-on controls
only at facilities with high-sulfur raw materials, EPA has proposed a
limit of 1.33 lb of SO2 per ton of clinker, whereas the average emission
rate from just 18 data points from tests at facilities with moderate
levels of sulfur in raw materials was 1.3 lb/ton. EPA’s assumption
that facilities with low and moderate levels of sulfur in raw materials
would not have to install controls to meet the proposed SO2 standards is
not justified by those data. Requiring facilities with moderate
uncontrolled SO2 emission levels to use add-on controls for SO2 would
result in excessively high costs per ton of SO2 removed, as EPA has
recognized. Also, the energy penalty associated with wet scrubbers could
more appropriately be evaluated on a case-by-case basis, where it can be
weighed against factors such as the level of uncontrolled SO2 emissions
at the particular plant and the need for further SO2 reductions at that
location for attainment and maintenance of SO2 ambient air quality
standards.

Commenter 64 states that because there is so little experience with
add-on SO2 controls, EPA has relatively little data about the
performance of those controls, and is proposing NSPS for SO2 based
solely on a recent BACT determination. The few kilns that will be
subject to the proposed Subpart F NSPS can be addressed through
requirements for SO2 control derived through the RACT process or through
NSR.

Commenter 64 states that if EPA persists in setting SO2 standards, there
are a number of problems with the standards as proposed. For example,
the percentage reduction alternative does not indicate that it is to be
calculated on a 30-day basis or how the percentage reduction is to be
calculated. The commenter infers from the monitoring provisions that EPA
intends for a source to compare the SO2 concentration at the inlet to
the scrubber to the SO2 concentration at the outlet from the scrubber,
but this does not reflect the substantial reduction in SO2 emissions
that occurs from contact with alkaline materials in the process. The
commenter states that cement plants with moderate uncontrolled SO2
emissions may have to install controls and the 90 percent reduction
standard likely would be unachievable when applied to the relatively low
inlet concentrations to the control device. The commenter states that it
is even less clear how EPA would apply the percentage reduction standard
to cement plants that choose to use lime injection

Commenter 64 states that the proposed regulations lack any discussion of
whether the SO2 limitations apply during periods of startup, shutdown,
and malfunction. Since substantial reduction of SO2 occurs naturally in
the cement-making process because of the alkaline nature of the raw
feed, commenter 64 states it would be reasonable to provide an exemption
so that a wet scrubber or a lime injection system need not be operating,
or operating at maximum efficiency, during periods of startup, shutdown,
or malfunction. The commenter states that several recent BACT
determinations involving scrubbers include special provisions for
startup, shutdown, or malfunction.

Commenter 64 states that the proposed limits for SO2 appear inconsistent
with their stated technology bases, when compared to actual experience
and to BACT determinations. According to the commenter, the majority of
BACT determinations in the past 10 years that rely only on inherent SO2
reduction established limits higher than 1.33 lb/ton of clinker, except
for plants in Florida, where the BACT determinations often recognized
that raw materials are low in sulfur. According to the commenter, NSPS
should be based on demonstrated technology that can be applied to the
sector as a whole, rather than based on raw materials that are available
only in a limited area of the country. These BACT determinations also
undermine EPA’s stated assumption that 1.3 lb/ton represents a
“moderate uncontrolled SO2 emission rate” and 13 lb/ton would be
“a high uncontrolled SO2 emission level,” since almost all BACT
determinations for plants other than those in Florida imposed SO2
emission limits based on no add-on controls higher than 1.3 lb/ton, and
a number were higher than 13 lb/ton.

Commenter 64 states that if EPA insists on promulgating NSPS for SO2, it
is essential that the standards retain the proposed option of meeting
either a pounds per ton of clinker or a percentage reduction limit, but
both limits should be higher than proposed. According to the commenter,
the three wet scrubbers operated by Holcim were not designed to achieve
90 percent reduction, and the one BACT determination that contains an
estimated percentage reduction in the RBLC uses 85 percent reduction.
Importantly, cement plants in arid venues may not have the option to use
a wet scrubber because of water restrictions. Especially if EPA persists
in applying the revised NSPS to existing, modified or reconstructed
facilities, wet scrubbers cannot be considered demonstrated available
technology for all facilities in the source category. EPA does not, and
Commenter 64 believes EPA cannot, support a 90 percent reduction
requirement using dry scrubbers or lime injection. According to the
commenter, to qualify as a limit based on demonstrated technology, the
limit should be achievable at all types of plants, raw materials, and
locations, and should be based on actual performance data rather than
what is “reportedly” achievable or anticipated.

Commenter 64 states that 1.33 lb/ton does not represent even the
technology basis—alkaline wet scrubber on high-sulfur raw
materials—that EPA has identified. The commenter states that EPA
describes one kiln where uncontrolled SO2 emissions are “about 13
lb/ton of clinker.” Achieving 90 percent reduction of that
uncontrolled emission rate would just meet the proposed mass limit, with
no margin of compliance. And in any event, at least four of the BACT
determinations for cement kilns in the past 10 years reported in the
RBLC reflect uncontrolled SO2 emission rates over 20.0 lb/ton. The
proposed limit of 1.33 lb/ton thus does not reflect a limit that has
been demonstrated as achievable applying wet scrubber technology to the
range of sulfur contents present in cement plant raw materials.

One commenter (74) states that the proposed SO2 limit may be achievable
in most cases but different plants will require different solutions to
achieve that limit. Due to the large variations in the elemental and
pyritic sulfur from plant to plant, Commenter 74 does not believe that
it is fair to have a set SO2 limit for all plants. Each plant's limit
should be considered on a case by case basis considering the elemental
or pyritic sulfur level in the raw materials and a reasonable target for
the cost per short ton of removal to determine the controls that are
used. In some cases this will give a limit lower than 1.33 lb/ton
clinker and in other cases it will give a higher limit.

One commenter (75) states that: 1) Given the range of pyritic sulfur in
our raw material, we would need to have a wet scrubber to meet this
limit; 2) Lime injection is an effective control with less secondary
impacts on water supply and energy use; and 3) A limit of 4 lb/ton of
clinker should be adopted. This would allow greater use of lime
injection, providing significant SO2 reductions while avoiding secondary
adverse environmental impacts and energy use of wet scrubbing. The
commenter does not believe that the proposed limit adequately reflects
the inherent variability of kiln emission rates, which are dictated by
the characteristics of the raw feed to a kiln. Commenter 75’s kiln
feed is locally mined raw materials used for over 100 years, with plans
to continue the present mining operation for many years in the future.
The standard, as proposed, would impose economic and environmental
impacts beyond those considered by EPA.

Response: See the preamble for the response.

Comment: One commenter (73) states that the proposed 1.33 lb/ton of
clinker limit or 90 percent or more SO2 reduction implies that: 1) If a
kiln achieves 1.33 lb/ton of clinker without the need for any add-on
SO2 control technology, it would meet the NSPS; 2) If uncontrolled SO2
emissions exiting the raw mill are between 1.34 and 13.3 lb/ton of
clinker, control technology capable of reducing SO2 emissions to 1.33
lb/ton of clinker would be required to meet the NSPS; and 3) If
uncontrolled SO2 emissions exiting the raw mill are greater than 13.3
lb/ton of clinker, a control technology capable of 90 percent or greater
control is required to meet the NSPS. The commenter states that if this
is not EPA’s interpretation, then EPA should adopt the approach
outlined above, and make appropriate changes to the regulatory language
to make this clear.

Response: The commenter’s interpretation is not entirely correct. In
light of the final limits for SO2, if SO2 emissions from a kiln exceed
0.4 lb/ton clinker, the owner or operator has two options: install a
control device or modify the process so that emissions are reduced to
less than 0.4 lb/ton, or; install a scrubber or other control device
than achieves at least a 90 percent reduction in emissions across the
control device.

Comment: One commenter (76) states that pyritic sulfur is the main
contributor to SO2 emissions in cement plants. The Fe2S2 releases its
sulfur around 400°C, which fits nicely into the fourth stage (counting
from the lowest stage to the highest) of a typical preheater temperature
profile. The magnitude of the SO2 emission is simply a calculation of
the total potential SO2 emission minus how much will be absorbed by the
system. To bring a Colorado, or Texas cement plant’s SO2 level down to
that of a plant in Florida, would require extensive secondary abatement.
In extreme cases, secondary abatement could consistently lower the SO2
emission by 90 percent; therefore as long as the uncontrolled SO2
emission from pyritic sulfur and all other sources does not exceed 13.3
lb/SO2 ton of clinker, then a continuous controlled rate of 1.33 lb
SO2/ton of clinker could be achieved.

Response: Under the final rule, the owner or operator of a kiln must
comply with the SO2 limit of 0.4 lb/ton of clinker or reduce SO2
emissions across the control device by 90 percent or greater.

Comment: One commenter (77) believes that with a properly designed
state-of-the-art preheater/precalciner kiln system, a continuous
controlled emission rate of 1.4 pounds of SO2 per ton of clinker can be
achieved by all new kiln applications which have minimal pyritic sulfur
in their raw materials. On plants with unusually high pyritic sulfur in
their raw materials Commenter 77 believes that with add-on controls, a
reduction of 90 percent will be possible.

Response: In contrast to the commenter’s recommendation for a limit of
1.4 lb/ton clinker, kilns currently operating with minimal pyritic
sulfur in their raw materials, for example kilns in Florida, have
emission rates ranging from 0.02 to 0.3 lb/ton clinker (Docket item
EPA-HQ-OAR-2007-0877-0022). For kilns processing high pyritic sulfur raw
materials, we agree that a 90 percent reduction is achievable. We think
that a properly designed scrubber can achieve better than a 90 percent
reduction. For example, emission results from a scrubber-controlled kiln
in Texas that processes raw materials with a high sulfur content show
SO2 removal efficiencies ranging from 91 to 99 percent with an average
of 94 percent (Docket item EPA-HQ-OAR-2007-0877-0022).

Comment: One commenter (83) supports the proposed SO2 standard of 1.33
lbs/ton clinker as a reasonably achievable standard. The commenter would
like for EPA to clarify that the limit is stack specific as opposed to a
facility-wide limit, which means that kilns with both main and bypass
stacks would not combine their emissions for compliance purposes but
instead only have to meet the limit at each stack. Otherwise, the
commenter states that the standard would be too stringent.

Response: For a kiln with a bypass, compliance with the SO2 limit will
be determined by measuring the SO2 emissions from the separate stacks
and summing the mass of SO2 emitted from the bypass and the kiln and
dividing the sum by the clinker production, i.e., emissions are to be
combined.

4.5	PM

Comment: One commenter (64) supports EPA’s decision not to set
separate limits for condensable PM, PM2.5, or PM10 stating that these
fractions of PM will be adequately controlled by facilities utilizing
control equipment sufficient to meet the proposed limits for PM. The
commenter also concurs that EPA does not have adequate data on the
emissions or the demonstrated capability of various control technologies
to meet any specified level of these fractions of PM. The commenter
states that they are not aware of any demonstrated or emerging
technology that would provide better control of PM2.5, PM10, or
condensable PM emissions specifically.

Response: The PM limits address filterable PM, including PM2.5 and PM10,
but not condensable PM. As the commenter states, EPA does not currently
have sufficient information on emissions of condensable PM from cement
kilns to set emission limits. The current information on emissions of
condensable PM is highly uncertain. Limited data indicate that emissions
of condensable PM is likely site-specific and variable. Although not
quantifiable at this time, EPA expects that the combination of PM
controls as well as wet scrubbers that are installed in order to comply
with the HCl emission limits being promulgated in the final NESHAP
amendments will result in a reduction of condensable PM, PM2.5 and PM10.

Comment: One commenter (64) agrees with EPA’s decision to not set a
lower PM emission limit for clinker coolers than kilns as they are not
aware of any technological basis for setting a lower PM limit and agrees
that data on clinker cooler PM emissions from three newer facilities are
not sufficient to fully reflect control device performance variability
at a single facility or among facilities.

Response: EPA is setting the same PM limit for kilns and clinker coolers
although the final limits of 0.04 lb/ton clinker (existing sources) and
0.1 lb/ton clinker (new sources) are more stringent than the PM limits
that were proposed.

Comment: One commenter (68) stated that they agree with EPA’s BDT
analysis and conclusion, and supports the PM NSPS level proposed.

Response: As described in the preamble, the statistical methods used to
establish the MACT floor limits were revised following proposal and
resulted in lower PM emission limits for existing and new sources. Even
though the final limits were derived under the MACT floor analysis, they
also reflect best demonstrated technology and the new source MACT PM
limit of 0.01 lb/ton of clinker is also the limit for new sources
subject to the NSPS. The final PM limit is now a 30-day rolling average
limit monitored using PM CEMS. It should be noted that due to the longer
averaging periods, the actual limit will be less compared to the shorter
compliance interval in the proposed rule (30 days versus a three hour
test).

Comment: One commenter (71) recommends that EPA set a PM emission limit
at a level that is significantly lower than 0.086 lb/ton clinker.
Commenter 71 states that current PM emission levels from existing kilns
and clinker coolers that utilize the traditional fabric bags to control
emissions are in the range of 0.069-0.098 lb/ton of clinker. The higher
end of this range is accompanied by visible emission. This may suggest
that these higher values maybe the result of bag leaks. If the EPA is
suggesting the use of membrane technology and bag leak detection (BLD)
systems, then clearly the proposed limit is not reflective of the effect
of the technology. Under normal operating conditions without bag leaks,
the membrane technology would practically eliminate the emission of fine
(inhalable) particulate and coupled with a BLD system would result in
emissions near a tenth of the proposed standard. The cost impacts would
be negligible since the real cost would be the increment between the
traditional fabric bags and membrane technology. In addition, the
literature and experience suggest that the greatest threat to human
health is fine particulate in the inhalable range. It is the fine
particles which provide the high reactive surface to promote smog
forming reactions. Further, it is also the fine particulate that will
impact visibility since it can be persistent in the atmosphere while the
larger species settle and it has the highest ability to disperse
radiation in the visible spectrum. Commenter 71 suggests that EPA should
consider establishing emission limits based on PM10 or PM2.5.

Response: We have decided to set the NSPS PM limit at the same level as
the NESHAP new source limit, 0.1 lb/ton clinker. This change would
address the comment above.

As discussed in the previous response as well as in the preamble, EPA
has set the final PM emission limits at 0.4 and 0.1 lb/ton of clinker
for existing and new sources, respectively and requires that emissions
be monitored using PM CEMS, with compliance based on 30-day rolling
averages. Although we have not set limits for fine particulate matter as
the commenter requested, the final regulations for mercury, HCl and SO2
will result in the co benefit of reducing fine particulate matter
emissions.

Comment: Several commenters (64, 73, 74, 83) expressed concerns over the
proposed NSPS for PM of 0.086 lb/ton of clinker. Commenter 64 states
that the proposed limit of 0.086 lb/ton of clinker is not supported by
the data available from new plants with the identified technology; it
does not allow for deterioration of performance over time; and it does
not allow for an adequate margin of compliance. Commenters believes that
EPA used insufficient data to develop the standard and failed to
consider situations where gases from kilns, clinker coolers, and coal
mills are combined for energy recovery purposes. Commenter 73 has spoken
to major suppliers of cement kiln systems and believes that baghouse
technology with membrane bags is capable of achieving a continuous
outlet grain loading rate of 0.010 gr/dscf. Applying EPA’s factors for
standardized volumetric flow and feed-to-clinker ratio (54,000 dscf/ton
of feed and 1.65 tons feed/ton clinker), an appropriate NSPS PM standard
would be 0.127 lb/ton of clinker for cement kilns and clinker coolers.
Commenter 73 and 74 also believes that when clinker cooler and kiln
gases are combined, the standard for these systems should be additive.

The commenters stated that the standards must be set at a level that
recognizes that there will be some deterioration in performance over
time. According to the commenters, in most cases, emission rates
achieved immediately after installation of pollution control equipment
will not be representative of the performance over the life of the
source, as the bags and the baghouse itself age and experience normal
wear, even with proper operation and maintenance. Commenter 73 agrees
with EPA that “fabric filters control generally to the same
concentration irrespective of the PM loading to the filter inlet, though
some variability in PM emissions from fabric filters does occur due to
seepage and leakage.” It is the seepage and leakage that becomes an
issue as baghouses age. Commenter 64 states that the PM stack testing
data used by EPA in their analyses were obtained from kiln-baghouse
systems that had operated for less than 5 years and therefore, EPA has
not demonstrated that they have proposed a limit that new sources can
sustain long term. EPA has recognized this in numerous other
rulemakings, including in setting emission standards for hazardous air
pollutants at new cement kilns burning hazardous waste where they
amended the PM limits for new sources in that NESHAP based on data
demonstrating that the original PM standard was “overly stringent in
that it does not fully reflect the variability of the best performing
source over time.”

Response: For a discussion of issues raised by these commenters, see the
preamble. See also section 2.8.2 of the comment and response document
for the final NESHAP.

Comment: Commenter 64 submitted recent PM test data from 25 preheater
and preheater/precalciner kilns consisting of 42 separate Method 5
tests. The data includes information on whether bags were membrane bags
and whether the raw mill was on or off. The commenter evaluated the data
and drew the following conclusions:

The test results were not statistically normally distributed.

The average emission rate for membrane equipped bags was 0.077 lb/ton
clinker and 0.091 for conventional bags.

Using the Mann Whitney test, the difference in the means for the bag
types was not statistically significant.

Average emissions during mill off conditions were statistically higher
than emissions during mill on conditions.

Based on a number of test results for three Florida kilns, there is
substantial day-to-day variability that must be considered in setting
the NSPS.

The upper 95% confidence interval for the test data is 0.108 lb/ton
clinker which is approximately 0.01 gr/dscf (or 0.127 lb/ton clinker),
the same as the achievable limit recommended by cement design firms.
Commenter 83 also supports a PM limit of 0.127 lb/ton clinker.

Response: In developing its final PM emission limits, EPA evaluated data
submitted by the commenter along with data collected previously as well
as data submitted following the proposal of the NESHAP amendments. Data
submitted by the commenter appeared to contain kilns that were lower
emitters than kilns in our original group of kilns; we requested test
run results for those kilns from the commenter. PM emissions limits were
developed as MACT floor limits, which under the final rule, include
limits for new kilns subject to the final NSPS as well. Under the MACT
floor approach, the top performing kilns were selected based on the
average of their emissions test results. We noted, as did the commenter,
that PM emissions tend to be greater during mill off than mill on
conditions. To determine a kiln’s ranking where we had tests under raw
mill on and off conditions, we used weighted average emissions to
account for the differences. For two top performing kilns, we had only a
single test (three runs each); we requested additional data for those
kilns and were able to add an additional six test runs for each of the
two kilns. In addition, one commenter submitted additional test data for
its kiln that was one of the top performers. From the 45 kilns for which
we had adequate emissions data to evaluate, we identified the top 12
percent, or top 6 kilns. Using a revised upper prediction limit (UPL)
formula, we assessed the data variability to establish the MACT floor
limits for existing and new kilns. The statistical method is further
discussed in the preamble.

Regarding the comment on the performance of membrane bags in comparison
to standard bags, high efficiency membrane filters under testing in
EPA’s Environmental Technology Verification (ETV) Program, have on
average significantly outperformed non-membrane depth filters in
controlling PM and PM2.5 as well as in other performance areas including
average residual pressure drop and cleaning cycles. (World Cement, April
2007) Use of membrane bags is expected to reduce baghouse maintenance,
extend bag life and reduce operational incidents such as increased
opacity, and enable higher production levels. (W.L. Gore and Associates,
Optimizing Kiln Operations by Improving Baghouse Performance, 2001).

Comment: Commenter 73 believes that EPA may not have adequately quality
controlled the data used in its analyses. For example, the Lafarge Sugar
Creek data used by EPA in their analyses came from a performance test
that was done to demonstrate compliance with the PM10 standard. Thus,
this data is PM10, not PM.

Response: As a result of this comment, the PM data in question was
re-examined. The Missouri Department of Natural Resources was contacted
for clarification of the 2002 test data for the Lafarge kiln at Sugar
Creek, MO. The initial testing to determine MACT compliance included
testing for PM as well as PM10. The results used in our analysis were
for PM and not PM10. The documents containing the results referred to
here can be viewed in Docket No. EPA-HQ-OAR-2002-0051, docket items
2002-0051-2024 and 2002-0051-2039.

Comment: One commenter (75) stated that the proposed NSPS will require
the use of baghouses equipped with membrane filters, which will present
an additional capital cost over typical fabric filters in addition to an
additional increase in maintenance over traditional filters, and that
baghouse designs will be larger, increasing space requirements and
energy consumption.

Response: The commenter is correct that new baghouses may require the
use of membrane filters to comply with the NSPS PM limit and that the
capital cost of these filters is greater than conventional fabric
filters. However, EPA disagrees with the other claims made by the
commenter. Because membrane bags utilize surface filtration rather than
depth filtration of conventional fabrics, membrane bags require less
aggressive cleaning, which greatly prolongs bag life in comparison to
conventional fabric, and operate at higher air-to-cloth ratios
requiring, which would translate to smaller baghouse designs. Also, the
trend in baghouses in the cement industry is to smaller pulse-jet
baghouses. More importantly, under testing in EPA’s Environmental
Technology Verification (ETV) Program, membrane filters have on average
significantly outperformed non-membrane depth filters in controlling PM
and PM2.5 as well as in other performance areas including average
residual pressure drop and cleaning cycles. (World Cement, April 2007)
Use of membrane bags is expected to reduce baghouse maintenance, extend
bag life and reduce operational incidents such as increased opacity, and
enable higher production levels. (W.L. Gore and Associates, Optimizing
Kiln Operations by Improving Baghouse Performance, 2001). The other
factor that will affect whether standard fabric filters are replaced
with membrane filters is the increased use of ACI systems, including a
polishing baghouse, to comply with the mercury emission limits under the
NESHAP. EPA anticipates that ACI systems will be placed downstream of
existing PM control devices because of the inability to recycle CKD
containing carbon from the ACI back to the kiln. Recycling CKD is a
common practice in the industry. The result is that many kilns will be
equipped with two PM control devices in series, in which case it is
unlikely that standard fabric bags will need to be replaced with
membrane bags in order to achieve compliance with the PM limit. Because
new kilns will be subject to PM limits that were developed as part of
developing the MACT floor limits under the NESHAP for portland cement
manufacturing, costs incurred to comply with the final PM limits are
attributable to the NESHAP rather than the NSPS.

Comment: Commenter 75 asks that EPA consider a grain loading limit of
0.01 gr/dscf as a more practical alternative to the lb/ton of feed limit
noting that PM emissions limits are typically based on grain loading
(gr/dscf) which is more representative measures of PM emissions, and is
not dependent upon production rate. A gr/dscf limit would better reflect
the actual efficiency of the control device, regardless of the
production rate.

Commenters75, 76 and 77 stated that modern baghouses can consistently
achieve a continuous outlet grain loading of 0.010 gr/dscf. Of course,
this emission rate can only yield a lb of particulate/ton clinker value
when converted using the site specific volumetric flow rate and
feed-to-c1inker conversion factor. Here again, both values vary from
site to site and must be evaluated on an individual basis. For that
reason, the commenters would not suggest a lb of particulate/ton clinker
PM limit; but a gr/dscf limit.

Response: As discussed in the preamble, EPA developed PM limits for
existing (0.04 lb/ton clinker) and new kilns (0.01 lb/ton clinker) using
the MACT floor approach; the PM limits for new kilns are also applicable
to new kilns under the NSPS. In response to the comment that the limit
should be set at 0.1 gr/dscf, EPA analyzed the grain loading data for
the MACT floor kilns to determine what the PM limit would be if we were
to put the limit in units of gr/dscf. The average grain loading of the
MACT floor kilns is 0.002 gr/dscf. The MACT floor limit based on the UPL
for these top performing kilns would be 0.004 gr/dscf, well below the
commenter’s suggested 0.1 gr/dscf.

In response to the commenter’s suggestion that EPA use gr/dscf as the
format for the PM limit, EPA believes, as we stated in the preamble to
the proposed rule, that an output-based standard, i.e., lb/ton of
clinker, promotes efficiency among the sources as opposed to input or
concentration based standards. An output based standard is also
consistent with permit limits set by many states that we reviewed. A
disadvantage of the concentration standards is that emissions can
increase as a result of the intentional or unintentional addition of
dilution air to the exhaust gas stream which has the effect of reducing
the concentration but not emissions. For these reasons EPA did not
replace the output based standard with concentration based limit or
offer one as an alternative to the output based limit.

The PM data for the top performing kilns under the NESHAP resulted in a
MACT floor limit of 0.04 lb/ton of clinker for existing kilns and 0.01
lb/ton of clinker for new kilns. As required by the CAA and subsequent
court rulings, EPA is bound to establish limits of the top performers.
Even considering the data of the top performing kilns in gr/dscf, the
limit for existing kilns as described above is well below the
commenters’ recommended 0.1 gr/dscf.

4.6	Opacity

Comment: One commenter (64) agrees that there is no basis for revising
the current NSPS standards that apply to affected facilities at portland
cement plants other than the cement kiln and the clinker cooler and
states that they are not aware of data that would support imposing a
limitation more stringent than the current 10 percent opacity standard.
The Commenter 64 further states that an opacity standard below 10
percent could not be determined reliably due to the margin of error
associated with the EPA Method 9. Commenter 83 urges EPA to maintain the
existing subpart F opacity limits.

Response: We are removing 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.

Comment: One commenter (69) believes that all kiln stacks should be
subject to a 20 percent opacity limit as is currently required in the
existing portland cement plant NSPS. Kiln stack emissions have the
potential to form a secondary (reactive) plume after the exhaust gases
exit the stack. There have been instances where a certified in-stack
continuous opacity monitor (COM) read opacity well below 20 percent
while opacity observations of a certified Method 9 reader were in the
40-60 percent opacity range. The disparity between the COM readings and
the Method 9 readings were attributed to exhaust gases reacting upon
exit of the stack to form a secondary plume approximately 300-500 feet
downwind of the stack exit. Commenter 69 supports the proposed rule's
requirements regarding kiln stack particulate monitoring using bag leak
detection systems, electrostatic precipitator predictive models, and
continuous emissions monitors. However, Commenter 69 does not support
allowing facilities that use these particulate monitoring systems to be
exempt from a kiln stack opacity limit.

Response: See the previous response.

4.7	VOC and CO

Comment: One commenter (59) states that a co-benefit of using SCR system
to control NOx emissions is that they simultaneously reduce VOC
emissions and organic HAPs including dioxins, furans, and ammonia. The
commenter states that SCR removes greater than 80 percent CO, and
greater than 70 percent of VOCs.

Response: EPA agrees with the commenter that one of the advantages of
SCR technology for NOx control is the co-benefit of simultaneously
reducing emissions of other pollutants, including VOC and possibly CO.
But as discussed earlier (see section 4.3), the limited application of
SCR technology in the cement manufacturing industry (three kilns in
Europe and none in the United States) and known potential for mechanical
problems in operating the technology leaves EPA unconvinced that SCR
qualifies as best demonstrated technology. As a result, the final
emission limits for NOx are based on the use of well designed combustion
systems in conjunction with SNCR technology, which has been demonstrated
on numerous kilns operating in the United States.

Comment: Commenters (64, 73) support EPA’s conclusion that revised
NSPS for portland cement plants should not be expanded to include
limitations for carbon monoxide or volatile organic compounds. The
commenters agree that fuel-efficiency considerations already assure that
CO emissions from incomplete fuel combustion are minimized. The
commenters also agrees that the THC limitation in the portland cement
NESHAP will assure that cement plants subject to the proposed Subpart F
NSPS will not emit excessive levels of VOCs.

Response: EPA acknowledges that the commenters are in agreement with
EPA’s decision to not establish new source performance standards for
VOC and CO.

Comment: One commenter (71) believes that EPA should take this
opportunity to also set appropriate VOC and CO emission limits for
cement kilns. Based on the testing conducted at a long dry cement kiln,
the uncontrolled VOC and CO emission levels are in the range of
0.62-0.70 and 1.62-2.14 lb/ton of clinker, respectively. These
uncontrolled VOC and CO emission levels can be reduced once the
appropriate control technologies are identified. Commenter 71 encourages
EPA to further review available test data for cement kilns, identify
appropriate control technologies, and establish achievable limits.

Response: As discussed in the final rule, non-dioxin THC emissions, most
of which are VOC, are being regulated under the final NESHAP amendments.
Under the final amendments to the NESHAP, THC limits of 24 ppm are being
set for existing and new sources, thus there is no need to establish new
source performance standards for VOC.

As described in the proposed rule, highly efficient combustors in
precalciner kilns will minimize emissions of CO from burning fuel. In
cases where the organic content of the raw materials is high enough to
emit high levels of CO, THC emissions will also be elevated and require
that the facility take steps to comply with the NESHAP limits for THC.
Therefore, elevated CO levels that occur in conjunction with elevated
THC levels will be controlled as part of a plant’s control of THC
emissions.

4.9	Fugitives

Comment: One commenter (68) strongly recommends that EPA promulgate NSPS
for fugitive emissions from clinker storage piles, raw materials
handling, and baghouse fall-out from cement plants. These sources of
fugitive emissions contain not only fine particulate emissions, which
pose substantial harmful effects to public health, but a number of
inorganic hazardous air pollutants, such as arsenic, mercury and
hexavalent chromium. The commenter cites a recent California study
indicates that high levels of hexavalent chromium, in particular, are
emanating from portland cement facilities. Specifically, storage piles
of clinker should be either partially or, preferably, fully enclosed;
installation of wind screens should be considered; and other corrective
work practice measures evaluated and promulgated.

Response: See the preamble for a discussion of actions that EPA is
taking regarding fugitive emissions from handling and storage piles.

4.10	Overall Achievability

Comment: One commenter (64) has concerns about the overall achievability
and cost effectiveness of the proposed NSPS. First, it does not appear
EPA has given sufficient consideration to whether each of the individual
proposed emission limitations can be achieved, or achieved at reasonable
cost, at the same time as other proposed NSPS emission limitations and
other applicable emission limitations. EPA has not identified any cement
plants that employ the combination of measures to achieve very low PM
emissions, NOx reductions, and SO2 reductions that form the basis for
the proposed NSPS. Commenter 64 urges EPA to give additional
consideration to these interactions that may occur when the various
control technologies identified in the proposed NSPS are employed
together.

One commenter (77) understands the newly proposed NSPS limits for SO2,
NOx and PM may be achievable in a large number of projects. Commenter 77
also states that these new limits would not be achievable for all
projects as would be required by these new NSPS limits. Current cement
plant process technology and equipment are very effective at minimizing
the potential air pollutant emissions through state of the art
combustion technology and add on pollution control systems. Each plant
has specific raw materials and fuels which combine to make a variety of
cement types. All of these factors combined influence the potential
emissions of SOx, NOx, CO and PM. Detailed analysis and proper
application of various technologies are required for each different
combination of plant specific materials.

Response: EPA is mindful that it must set standards that reflect
achieved performance, that process inputs (raw materials and fuels) must
be accounted for in ascertaining sources’ performance, and that costs
be considered by EPA in ascertaining the level of the BDT. In
considering achievability, EPA established limits based on what best
performers actually achieved. EPA has carefully developed data for each
standard, assessing both process performance and technological controls
in doing so. For example, while EPA has set its limits for NOx based on
the use of low NOx processes and SNCR, it has rejected more stringent
limits based on SCR control technology that we do not consider to be a
clearly established NOx control technology in the cement industry. EPA
has also adopted 30-day averaging periods for all of the standards,
further allowing short term fluctuations to be averaged out over the
30-day period. The result are limits that reasonably estimate the
performance over time of the best demonstrated technology. It is true
that many sources will need to install controls to meet these standards,
and that these controls have significant costs. This is part of the
expected process where, by definition, new sources will need to perform
at levels above what is achievable by most existing sources. The Agency
believes that it has utilized best efforts to follow the statute and
applicable caselaw, and has not adopted standards which are