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									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
1.        Introduction ..........................................................................................................................1
2         Legal Issues Related to EPA‘s Interpretation of the CAA ..................................................4
          2.1     Best Demonstrated Technology .............................................................................. 4
          2.2.    Greenhouse Gases ................................................................................................... 4
          2.3     Emission Limits ...................................................................................................... 6
          2.4     Pollutants not Included (VOC, PM2.5 ) .................................................................... 9
          2.5     General .................................................................................................................. 10
3         Applicability.......................................................................................................................12
          3.1     Modified Kilns ...................................................................................................... 12
4         Emission Limits .................................................................................................................16
          4.1     General .................................................................................................................. 16
          4.2     Format ................................................................................................................... 16
          4.3     NOx........................................................................................................................ 16
          4.4     SO2 ........................................................................................................................ 24
          4.5     PM ......................................................................................................................... 30
          4.6     Opacity .................................................................................................................. 35
          4.7     VOC and CO ......................................................................................................... 36
          4.9     Fugitives................................................................................................................ 37
          4.10 Overall Achievability ............................................................................................ 37
5         Monitoring and Recordkeeping .........................................................................................39
          5.1     SO2 ........................................................................................................................ 39
          5.2     PM ......................................................................................................................... 40
          5.3     Opacity .................................................................................................................. 40
          5.4     CEMS.................................................................................................................... 41
          5.5     Clinker Production ................................................................................................ 42
6         Test Methods and Procedures ............................................................................................43
7         Impacts ...............................................................................................................................44
          7.1     Cost and Cost Effectiveness.................................................................................. 44
          7.2     Environmental and Energy.................................................................................... 46
          7.3     Economic .............................................................................................................. 48
          7.4     Multipollutant........................................................................................................ 49
8         Miscellaneous.....................................................................................................................50
          8.1     Proposed Rule ....................................................................................................... 50
          8.2     Technical Support Document................................................................................ 51


                                                          List of Tables

Table 1-1. List of Commenters on Amendments to 40 CFR 60 Subpart F Proposed June 16,
       2008 (73 FR 34072) .............................................................................................................2




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                                    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




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Table 1-1. List of Comme nters on Amendme nts to 40 CFR 60 Subpart F Proposed June 16,
                                   2008 (73 FR 34072)

Docket No. EPA-HQ-OAR-2007-0877             Commenter Name, Affiliati on, and Date Recei ved
                                  Anonymous Public Co mment
056
                                  August 15, 2008
                                  Kevin Batchelder
057                               EnviroLog ix, Inc.
                                  July 10, 2008
                                  Al Armendariz, Ph.D.
059                               Private Citizen
                                  September 17, 2008
                                  A. A. Linero, P.E., Program Ad min istrator
                                  Bureau of A ir Regulat ion
060
                                  Florida Depart ment of Environ mental Protection
                                  September 29, 2008
                                  Michael H. W inek
                                  Babst, Calland, Clements, and Zomnir
061
                                  On behalf of Armstrong Cement and Supply Corporat ion
                                  September 30, 2008
                                  Ed mund G. Brown Jr., Attorney General o f California
                                  Joseph R. Biden, III, Attorney General of Delaware
                                  Martha Coakley, Attorney General of Massachusetts
062                               Andrew M. Cuomo, Attorney General of New Yo rk
                                  Hardy Myers, Attorney General of Oregon
                                  William H. Sorrell, Attorney General of Vermont
                                  September 30, 2008
                                  Caro lyn Slaughter, Program Develop ment Manger
063                               Institute of Clear Air Co mpanies (ICA C)
                                  September 30, 2008
                                  Andrew T. O‘Hare, Vice President Regulatory Affairs
064                               Portland Cement Association (PCA )
                                  September 30, 2008
                                  Timothy Ballo
                                  James Pew
065                               Janette Brimmer
                                  Earthjustice on behalf of Clean A ir Task Force and Downwinders At Risk
                                  September 30, 2008
                                  Melanie Sattler, Ph.D, P.E.
066                               Private Citizen
                                  September 30, 2008
                                  Shelly Kaderly, Air Quality Division Admin istrator
067                               Nebraska Depart ment of Env iron mental Quality (NDEQ)
                                  September 30, 2008
                                  Robert Hodanbosi, Co-Chair Permitting Co mmittee
                                  Ursula Kramer, Co-Chair Permitting Co mmittee
068
                                  National Association of Clean Air Agencies (NACAA)
                                  September 30, 2008
                                  J. Jared Snyder, Assistant Commissioner
                                  Office o f Air Resources, Climate Change, and Energy
069
                                  New York State Depart ment of Environmental Conservation
                                  September 30, 2008




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Docket No. EPA-HQ-OAR-2007-0877                   Commenter Name, Affiliati on, and Date Recei ved
                                         Myra C. Reece, Chief
                                         Bureau of A ir Quality
070
                                         South Carolina Depart ment of Health and Environmental Control
                                         September 30, 2008
                                         Mohsen Nazemi, P.E., Deputy Executive Officer
                                         Engineering and Co mpliance
071
                                         South Coast Air Quality Management District (A QMD)
                                         September 30, 2008
                                         Downwinders At Risk
072
                                         September 30, 2008
                                         Craig S. Campbell, Vice President
                                         Environment and Govern ment Affairs
073                                      Lafarge No rth America
                                         Cement Div ision
                                         September 30, 2008
                                         Steven Miller, Product Manager
                                         Pyroprocessing Technology
074                                      Ove L. Jepsen, Senior Vice President, North A merica
                                         FLSmidth Inc
                                         September 29, 2008
                                         Spencer Weit man, President
075                                      National Cement Co mpany of Alabama, Inc.
                                         September 30, 2008
                                         Mark S. Terry, President
076, 082*                                Polysius Corp, a ThyssenKrupp Technologies Company
                                         September 26, 2008
                                         Richard T. Cusick, President
077                                      Hu mboldt Wedag, Incorporated
                                         September 22, 2008
                                         Michael Pelan and Craig Campbell
                                         Environment and Govern ment Affairs
078                                      Lafarge No rth American
                                         Cement Div ision
                                         June 30, 2008
                                         Andrew T. O‘Hare, Vice President
                                         Regulatory Affairs
079**
                                         Portland Cement Association (PCA )
                                         June 17, 2008
                                         Andrew T. O‘Hare, Vice President Regulatory Affairs
080                                      Portland Cement Association (PCA )
                                         September 25, 2008
                                         Roger Bro wer, Principal
081                                      Zephyr Environ mental Corporat ion
                                         June 09, 2008
                                         Satish Sheth
                                         Vice President – Environ mental U.S. Operations
083
                                         Cemex, Incorporated
                                         May 05, 2009
*Duplicate copies of same co mments entered in docket.
** Request for extension of public co mment period.




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          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 (NO x ) 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



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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 CO 2 emission from cement plants and EPA‘s assertion that
       §111 does not compel the agency to regulate CO 2 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 CO 2 .
      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


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          pollutants that cause or contribute to such endangerment. Because cement plants emit
          CO 2 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 CO 2 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 CO 2 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 CO 2 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 CO 2 from cement plants. In
          addition to the suggested technologies, other measures that would also have CO 2
          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 SO 2 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.




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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 NO x 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 NO x but also volatile organic



                                                7
       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 NO x 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 NO x limits. If EPA indeed intends for the NSPS NO x 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 NO x 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 NO x limit in
this NSPS revision is dictated by the lack of any NOx limits in the existing NSPS. The absence of


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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, NO x 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 attributab le to SO2 emissions will be reduced
as a result of wet scrubbers that are installed to comply with the new limits for SO 2 . 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


                                                9
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 po llution 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. C ir. 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.



                                                 10
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 NO x 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.




                                                11
                                      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 SO 2 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 NO x 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 NO x and SO2 emission rates than older kiln technology. For NO x , this is due
to staging combustion and burning a significant amo unt 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


                                                 12
preheater/precalciner technology and that modificatio ns 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 NO x 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 NO x 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 NO x 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 NO x 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 NO x 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 NO x 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


                                                13
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 SO 2 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 SO 2 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 SO 2 . 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 NO x
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


                                                14
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 SO 2 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.




                                                 15
                                   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 NO x , 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 NO x /ton
clinker and states that SCR is an effective and proven technology to reduce NO x 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 NO x , 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


                                                16
SCR companies believe that they can design and supply SCR systems for NO x 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 NO x 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 NO x 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 NO x emission limit should be lowered from 1.5 lb of NO x /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 NO x 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.


                                                17
      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 NO x 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 NO x /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 NO x /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 NO x /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 Arizo na. 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 NO x 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 NO x 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.


                                                 18
The commenter listed the following NO x 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 NO x 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, NO x 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 NO x , 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 NO x 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 mec hanical 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.




                                                    19
One commenter (72) states that the NSPS emission rate for NO x 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 NO x 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 NO x emissions such as:

   (1) 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;

   (2) 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);

   (3) 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;

   (4) Size/type of the preheater - new in- line calciners will normally give the lowest NO x
       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), NO x 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;

   (5) 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

   (6) SNCR efficiency and slippage - the ability of an SNCR system to reduce NO x 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).



                                                20
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 SO 3 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 NO x 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 NO x
emission of 3.8 to 4.2 lb NOx /ton of clinker. With a 50 percent NO x reduction rate from the
application of SNCR technology, a controlled emission rate of 1.9 to 2.1 lb NO x /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 NO x /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 NO x levels with integrated control systems, such as Multi-Stage
Combustion (MSC) installed on low NO x 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 NO x 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 NO x limit applies only to a kiln‘s main stack or whether it applies across both the
main and bypass stacks.



                                                21
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 NO x 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 (s uch 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 NO x 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 NO x 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 NO x 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.


                                                  22
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-NO x 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 approp riate and
should be made on a case-by-case basis.

Commenters (64, 73) stated that the proposed NO x 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 NO x 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 NO x 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 NO x
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 NO x limit and applying SNCR.




                                                 23
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 NO x
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 NO x 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 SO 2 were
not sufficiently stringent. Commenter (60) recommends deleting the 90 percent reduction option,
revising the limit for SO 2 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 calc ination
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:



                                                 24
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 SO 2 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 SO 2 /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 DeSO x 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 NH 3 (from
an SNCR system), SO 2 , 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 SO 2 /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 lar ge wet scrubbers,


                                               25
dry scrubbers or coke filters. Finally selective mining of the available raw materials with respect
to sulfur content is an important SO 2 control strategy for any new project. In summary,
Commenter 60 recommends an NSPS SO 2 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 measure s 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 SO 2 -laden exhaust gases containing both raw
material and fuel sulfur.

Commenter 60 states that good SO 2 control will make it possible to employ more aggressive
NOx control and that the control of NO x and SO 2 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 SO 2
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 SO 2 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 SO 2 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


                                                26
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 SO 2 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 SO 2 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 SO 2 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 SO 2 controls, EPA has
relatively little data about the performance of those controls, and is proposing NSPS for SO 2
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 SO 2 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


                                                 27
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 SO 2 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 a vailable 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 SO 2 emission rate‖ and 13 lb/ton
would be ―a high uncontrolled SO 2 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 o r 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 categor y. 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 a ll 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 SO 2 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.



                                                28
One commenter (74) states that the proposed SO 2 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 SO 2
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 SO 2 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 SO 2 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 Fe2 S2 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 SO 2
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 SO 2 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/SO 2 ton of clinker, then a continuous controlled rate of 1.33 lb
SO2 /ton of clinker could be achieved.


                                                  29
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 SO 2 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 SO 2 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 examp le 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 SO 2 limit will be determined by
measuring the SO2 emissions from the separate stacks and summing the mass of SO 2 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


                                                30
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.


                                                 31
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 commenter s, 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.


                                                 32
      The average emission rate for membrane equipped bags was 0.077 lb/to n 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 wa s
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.



                                                33
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


                                                 34
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)


                                                 35
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 NO x
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 NO x 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.




                                               36
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, NO x 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 contro l 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 SO x , NOx , CO



                                                 37
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 NO x 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 impermissibly unachievable.




                                                38
                          5      Monitoring and Recordkeeping
Comment: One commenter (57) states that the proposed minimum requirement for valid data in
60.63(l)(1) is ―at least 18 hours in at least 22 out of 30 successive kiln operating days.‖ This may
need to be revised, depending on how EPA chooses to define a kiln operating day. The proposed
language is acceptable if a kiln operating day requires a kiln to operate the entire 24 hours in a
day. If a kiln operating day can include less than 24 operating hours, then the requirement for ―at
least 18 hours‖ is not feasible. EPA addressed a similar issue in 60.49Da(f)(1) and (2). Subpart
Da requires valid data for ―at least 90 percent of all operating hours‖ in an operating day when a
boiler operating day can include less than 24 operating hours.

Response: A definition of operating days has been added to the rule. A kiln operating day can
include less than 24 operating hours.

Comment: One commenter (57) states that EPA should consider allowing sources that have
NOx , SO2 , or stack flow CEMS certified and operated per 40CFR75 to use those CEMS to meet
the monitoring requirements. There are examples of this in 60.49Da(b)(4) and 60.49Da(c)(2).

Response: We agree that CEMS certified and operated per 40CFR75 could be used to meet the
monitoring requirements; an owner/operator can request alternative monitoring in such a
situation.

5.1    SO2
Comment: One commenter (64) states that with regard to SO 2 monitoring, EPA has not
provided adequate explanation of how monitoring data would be used to determine compliance
with the percent reduction option in the proposed SO2 standard, both for wet scrubbers and for
facilities that can comply using alkali injection. In addition, because EPA asserts that 80 percent
of cement plants subject to the proposed NSPS will not need any add-on controls to meet the
proposed standard, because they have low or moderate sulfur content in their raw materials, and
the nature of those raw materials is relatively stable, there is no justification for imposing the
added capital and operating cost of continuously monitoring SO2 emissions. Commenter 64
suggests that cement plant operators relying on low-sulfur raw materials and inherent SO2
reduction in the process should have the option of conducting an initial performance test for SO2 ,
with retesting at least once every five years, with no continuous monitoring of SO 2 required so
long as the stack test shows SO2 emissions less than 1.0 lb/ton.

Response: The SO2 compliance option of demonstrating a 90 percent reduction was intended to
apply to situations in which a wet scrubber is being used for compliance. In those instances, the
owner or operator may comply with either the SO 3 emission limit or the 90 percent reduction.
The 90 percent reduction is determined my continuously measuring SO2 at the inlet to the
scrubber and at the scrubber outlet. If a facility is using alkali injection, compliance is
demonstrated by meeting the SO2 emission limit of 1.33 lb/ton. The final rule has been revised to
make this clear.

In response to the commenter‘s suggestion that there is no need for SO2 monitoring where
scrubbers are not needed for SO2 control, it is possible that a source might change a raw material


                                                39
and significantly increase SO2 emissions beyond the standard. If monitoring is not in place, these
excess emissions could be unchecked for five years before they were discovered. We believe the
cost of the SO 2 monitor is reasonable to prevent these excess emissions. These monitors are well
established technology that are already installed on over 30 cement kilns, including those without
SO2 controls.

Comment: One commenter (68) strongly supports the requirements proposed by EPA for
continuous emissions monitoring for both SO2 and NOx to assure compliance with applicable
emissions limits.

Response: EPA acknowledges the commenter‘s support.

5.2      PM
Comment: One commenter (83) recommends eliminating the requirement for PM CEM
monitoring stating that the technology is neither sufficiently advanced nor reliable.

Response: EPA disagrees with the commenter‘s assertion that PM CEM is not sufficiently
advanced or reliable. It is currently required in other rules for the monitoring of PM emissions
and is used in Europe. EPA is replacing bag leak detectors and opacity monitoring and requiring
the use of PM CEMS to monitor PM emissions from all kilns and clinker coolers.

5.3      Opacity
Comment: One commenter (67) states that in the proposed changes to §60.62(a)(2) and (b)(2),
EPA proposes to exempt kilns and clinker coolers, with an applicability date prior to June 16,
2008, that use a baghouse leak detection (BDL) system, electrostatic precipitator (ESP)
predictive model, or a PM continuous emissions monitoring system (CEM) from opacity
standards. We have the following concerns:

      (1) The kilns and clinker coolers would not have an opacity standard per the NSPS if they
          have a PM monitoring system as an alternative to the COMS or daily Method 9 readings.
          Although the language in §60.62(d) indicates an intent by EPA to require the owner or
          operator of the affected facility to comply with the more stringent of two different
          requirements, the proposed language refers to ―another regulation in title 40 of this
          chapter.‖ Many states have a 20 percent maximum opacity standard in their state
          implementation plan (SIP) requirements. This could mean a relaxation of the opacity
          standard for the clinker coolers from 10 percent (current NSPS standard) to 20 percent
          standard.

      (2) If the PM monitoring system is not operating or is operating incorrectly, then opacity
          may exceed the opacity limit (20 percent or 10 percent as applicable) in the short term.
          The current opacity limit is for all of the time the kiln or clinker cooler is operational on
          or after the date the performance test is conducted per 40 CFR 60.8.

      (3) The proposed language in §60.62(a)(2) and (b)(2) only exempts kilns and clinker coolers
          from opacity limits if their applicability date was before June 16, 2008. Therefore, the



                                                    40
         newer kilns and clinker coolers (applicability date after June 16, 2008) would be subject
         to the opacity standards. The monitoring requirements for the newer units in §60.63(b)(2)
         includes the alternative PM monitoring options, but doesn‘t include a COMS.

      (4) Requirement §60.64(b)(6) in the proposal states that any unit subject to the 10 percent
          opacity limit must comply with §63.1350. The clinker coolers with applicability date
          after June 16, 2008 would be subject to the 10 percent opacity limit in §60.62(b)(2).
          Requirement §63.1350 requires a COMS to be installed or must conduct daily Method 9
          tests (for multiple stacks only).

Commenter 67 suggests EPA consider removing the exemptions in §§60.62(a)(2) and (b)(2) and
retaining the opacity limits. Requirements in §60.63(b) {PM requirements} and (c) {multiple
stacks alternative to COMS} allow for the alternative PM monitoring methods. If the exemption
remains, we suggest changing language in §60.62(a)(2) from "(a)(1)(i)" to "(a)(1)" and changing
language in §60.62(b)(2) from (b)(1)(i) to (b)(1), so that it is consistent on which units are
subject to the opacity limits.

Response: In the final rule, PM CEMS are required in place of bag leak detectors and/or opacity
monitoring on all kilns and clinker coolers.

Comment: One commenter (73) agrees with EPA that opacity monitoring for a kiln or clinker
cooler subject to the proposed NSPS is unnecessary if PM CEMS or bag leak detectors (BLD)
are installed. Further, Commenter 73 supports EPA‘s decision not to require PM CEMS, but
make it an option to BLD technology. Commenter 73 also supports compliance testing for PM
on an every five year basis.

Response: See the previous response.

5.4      CEMS
Comment: One commenter (63) supports the proposal to allow facilities to install PM CEMS as
there are several types of emissions measuring techniques that can be applied to combustion
processes. The commenter identifies different PM CEMS technologies and their costs.

Response: See the previous response.

Comment: One commenter (64) agrees that PM CEMS should be an option, not a requirement,
and that opacity monitoring is not necessary for a kiln or clinker cooler that employs a PM
CEMS or baghouse leak detectors or parametric monitoring of an ESP. Commenter 64 also
agrees that compliance testing every five years is adequate in light of the continuous monitoring
requirements. The commenter also supports the alternative in proposed section 60.63(c) for daily
visual opacity monitoring for control equipment with multiple stacks. Commenter 64 supports as
well EPA‘s proposal that sources subject to the current NSPS should have the option of installing
baghouse leak detectors or PM CEMS as an alternative to continuous opacity monitoring
(COMS).

Commenter 64 states that it is not clear from the wording of proposed section 60.63(b) if sources
choosing to install a PM CEMS need not also install and maintain baghouse leak detectors.


                                                 41
Commenter 64 recommends that EPA continue to allow COMS as a monitoring method, so that
a kiln or clinker cooler subject to the revised NSPS would have the option of monitoring
compliance with a COMS, a PM CEMS, or baghouse leak detectors. The commenter states that
EPA‘s justification is an insufficient basis for excluding a proven monitoring technique, which
cement manufacturers already know how to operate and maintain and which will cos t less to
install and maintain.

Response: See the previous response.

5.5    Clinker Production
Comment: Commenters (64 and 73) stated concerns about the requirement to continuously
monitor clinker output. The commenters are not aware of existing weigh scale systems currently
in use to measure clinker exiting the kiln or clinker cooler. According to the commenters, clinker
exiting the kiln and the clinker cooler is extremely hot and cannot be transported to storage by
conventional belt conveyor systems. Because drag and screw conveyance systems that are used
are not designed to incorporate weigh scale systems, a large majority of cement plants measure
clinker production by using a raw mix weigh scale system on the conventional belt conveyor
system feeding the kiln, and then applying a standard feed-to-clinker conversion factor. In the
pyroprocessing system, feed-to-clinker conversion is very constant which is especially the case
for PH/PC kilns. EPA should provide that as an alternative to the requirement to install a clinker
weigh scale system. The provision for approval of an alternative monitoring method is a
cumbersome and time-consuming approach that in practice will not be a practical substitute for
basing clinker output measurement on the demonstrated technology of weighing raw materials
and applying a conversion factor). The commenter included suggested regulatory language.

Response: We explicitly state in the NESHAP that a system that directly monitors feed rate and
uses a conversion factor to determine the clinker production rate is an acceptable method of
monitoring clinker production rates. The final rule language for the NSPS likewise makes this
clear.




                                                42
                           6       Test Methods and Procedures
Comment: According to one commenter (67) the statement in §60.64(b)(5), ―kiln (including any
associated alkali bypass and clinker cooler)‖ shall be tested every 5 years could be interpreted
that only clinker coolers associated with kilns subject to Subpart F have to be tested every five
years. Commenter 67 suggests EPA revise the language to state ―kiln (including any associated
alkali bypass) and clinker cooler,‖ which identifies the intention that each kiln and clinker cooler
has to be tested every 5 years. The 5- year testing requirement is for PM emissions only. There
are no NO x and SO2 testing requirements. This could be interpreted that the kilns or clinker
coolers with a PM CEMS must also conduct separate performance tests every 5 years in addition
to the annual relative accuracy tests that are required for the CEMS. If it is EPA‘s intent to
require PM performance testing every 5 years despite a PM CEMS, then it could be interpreted
that the PM CEMS is less accurate or reliable than the NOx or SO2 CEMS. If the annual relative
accuracy tests for the PM CEMS are equivalent to the 5-year testing, then we suggest an
exemption for kilns or clinker coolers with a PM CEMS. If the annual relative accuracy tests for
the CEMS are not equivalent to periodic performance testing, then we suggest a periodic (5- year)
performance testing for NOx and SO 2 should be added for the kilns which had commenced
construction, modification, or reconstruction after June 16, 2008.

Response: The identified section of the rule will be revised in light of the final requirement that
PM CEMS be used to monitor emissions from all kilns and clinker coolers,

Comment: One commenter (67) states that §60.64(b)(6) would require units subject to the 10
percent opacity limit to comply with §63.1350. The specific parts of the §63.1350 that these units
are subject to should be identified, because not all of the NESHAP requirements apply to these
units.

Response: The specific sections of §63.1350 that apply have been added to the rule (now at
60.64(b)(4)) as suggested.




                                                 43
                                        7       Impacts
7.1    Cost and Cost Effectiveness
Comment: One commenter (59) states that there was a high degree of consistency between the
three independent assessments of SCR cost effectiveness. The U.S. EPA median value of
$1,800/ton NO x was well within the range presented in the EU IPPC document, $1,500 to $3,800
per ton, and also was close to the value estimated by the blue ribbon panel for dry cement kilns
of $2,000 per ton. The blue ribbon panel also estimated the cost effectiveness for a series of
smaller older wet kilns at $5,800/ton NO x .

One commenter (63) states that the cost effectiveness of SNCR deployed on a PH/C cement kiln
is $700 ton/ NO x removed. In the evaluation of SCR‘s cost effectiveness in removing NOx from
a cement kiln a conservative threshold ranges from $1,800- $5,000 per ton of NO x controlled.

One commenter (60) states that according to the Swedish environmental agency ―the total cost
(of SNCR) with depreciation, capital cost, energy and ammonia related to NO x abated was is
approximately $325/ton of NOx removed. The commenter included the report from the Swedish
report as well as other reports on the performance of SNCR as attachments to the comment. The
commenter cites an example where the SNCR is operated to achieve a reduction from 6 to 1 lb
NOx /ton, the cost effectiveness would be less than $700/ton NOx removed.

Commenter 60 cites European cost comparisons of SNCR and SCR that show a cost
effectiveness for SNCR of $465/ton of NOx removed and $1,230/ton of NOx removed for SCR
assuming a conversion of $1.30/€.

Response: The EPA generally agrees with the commenter on the range of cost effectiveness for
SNCR and SCR. We consider SNCR to be BDT for NOx control. The final NO x limits are based
on the expected performance of SNCR (and proper control upstream of the end-of-stack SNCR)
and we believe it can and will be used to meet the final limit for NOx . While we see SCR as a
promising technology for NOx emission control, we have not set emission limits based on SCR
technology for reasons stated in the preamble to the final rule and other comment responses. We
will continue to monitor progress in the control of NOx emissions from the cement kilns and will
reconsider SCR at the appropriate time.

Comment: One commenter (64) stated that the proposed PM limit would have the effect of
requiring modified or reconstructed cement plants using an ESP to replace it with a fabric filter
using membrane bags and that EPA has simply ignored costs impacts for modified facilities that
will have to replace an ESP with a baghouse.

Response: In the final rule, the PM limits established under the NESHAP apply to both new and
existing sources. So regardless of whether a kiln is modified/reconstructed or not, it will be
subject to the revised PM emission limits. In estimating the impacts of the more stringent PM
limits under the NESHAP, we did evaluate kilns that were currently controlled by ESP to
determine the costs for such kilns. In addition, it is not clear that kilns equipped with an ESP
must necessarily remove them to meet the NESHAP/NSPS PM standard. We believe that most
kilns will have to install an activated carbon injection system with a polishing baghouse in order


                                                44
to comply with either the mercury emission limits or limits for organic HAP. As a result, it is
likely that a kiln currently equipped with an ESP will be adding a baghouse (as part of the ACI
system) downstream of the ESP and will be able to meet the final PM limit without replacing the
ESP.

Comment: One commenter (64) also believes that the cost-effectiveness discussion does not
reflect adequate consideration of the costs of achieving the emission reduction required by the
proposed standards as mandated by CAA section 111(a)(1). Commenter 64 does not believe that
simply comparing the costs per ton of pollutant removed to the costs per ton that has been
imposed in NSPS for the electric utility represents an adequate weighing of the costs involved.
Even based on EPA‘s cost estimates, the proposed NSPS would impose millions of dollars of
additional costs on each new or reconstructed or modified kiln, and tens of millions of dollars for
each kiln required to install a wet scrubber. These costs should be considered as well in
conjunction with costs already imposed by the portland cement NESHAP and the additional
costs that may be imposed as a result of the ongoing review of that NESHAP. These are costs not
borne by the industry‘s competitors in Canada and Mexico and elsewhere. EPA needs to provide
better justification that these costs are justified by the differences between the current Subpart F
NSPS and the proposed Subpart F NSPS.

Response: The MACT emission limits for PM will apply to existing and new kilns and will be
applicable to kilns subject to the NSPS. We have considered the costs of controls under both the
NSPS and the NESHAP as well as the economic impacts associated with those costs. See the
preamble for a discussion of the costs, economic impacts and benefits of the final amendments.

Comment: One commenter (75) states that the ―uncontrolled‖ inherent emissions of SO2
considered by EPA as representative of modern kilns are too high, thereby incorrectly making
wet scrubbing cost effective. EPA has used those sites currently operating wet scrubbers as the
basis for establishing ―high levels‖ of uncontrolled sulfur emissions. However, this is
inappropriate because it ignores fundamental technological differences between various cement
kilns. The commenter states that in one case, EPA used data from a facility where the scrubbers
are controlling emissions from wet kilns, not modern preheater/precalciner kilns. The other high-
sulfur facility that is referenced by EPA does not represent a new kiln. Rather, that project
reflects the addition of a preheater/precalciner to an existing kiln. In addition, the uncontrolled
SO2 emissions for this kiln approximated at 13 lb/ton includes approximately 8 lb/ton from the
alkali bypass stack and 4 lb/ton from the main stack. Modem kilns with high sulfur raw materials
can achieve inherent emissions on the order of 4.5 lb/ton. When the inherent emissions rate of
new kilns is considered, wet scrubbing is not cost effective or environmentally beneficial and
should not be considered BDT.

Response: Because of the requirements for HCl control on existing and new kilns under the
NESHAP, most kilns will be equipped with wet scrubbers or lime injection for the control of
HCl. As a result, new kilns subject to the revised NSPS will have their SO2 emissions
incidentally controlled. None of the cost of the scrubbers will be attributable to the final NSPS
amendments.

The commenter is taking issue with the uncontrolled SO2 emission levels we used in estimating
the impacts of the proposed standard. Although the cost of controlling SO2 is attributable to the


                                                45
NESHAP, we note that in the final analysis of impacts under the NESHAP, we did revise the
uncontrolled SO2 emissions to reflect the variation in SO2 emissions due to kiln type and
location. In order to examine the effects of kiln type, fuel and raw materials on SO 2 emission,
average SO 2 emission were estimated from 2002 National Emissions Inventory data in the
Cap+Trade workbook for each market by kiln type (Andover, September 23, 2008). Generally,
preheater and precalciner kilns had the lowest SO 2 emission rates while wet and long dry kilns
generally had the highest SO2 emission when comparing different locations. Location was
determined to play a significant role in SO2 emissions from kilns. Both mean and median
emissions were examined. Because median values tend to be less impacted by outliers than
means, median SO2 emission rates were used in the final analysis of air quality impacts.

7.2    Environmental and Energy
Comment: One commenter (75) states that the economic and environmental impacts of wet
scrubbing are understated. EPA estimated the cost effectiveness for reducing high unco ntrolled
SO2 emissions as less than $1,000 per ton of SO 2 removed. However, if the uncontrolled
emission rate is corrected to a more appropriate rate, the cost per ton increases due to two effects.
First, a lower uncontrolled emission rate results in less SO2 being removed, increasing the cost of
removal per ton of emissions. In addition, as the amount of SO 2 controlled is reduced, the
amount of synthetic gypsum available, and the gypsum credit, is reduced. The commenter states
that they believe that the credit for the use of scrubber derived gypsum used by EPA is too great.
Cement always includes gypsum at levels of around 5 percent by mass as a setting retarder. The
commenter estimated that the maximum quantity of gypsum recycled will be 23,342 tons/year,
which is well below the 84,101 tons/year listed in the example. Correcting this error further
reduces the cost effectiveness of wet scrubbing.

The commenter states that a wet scrubber would greatly increase the amount of water used by a
cement facility. The Southeast has experienced frequent drought conditions in recent years
restricting the amount of water available for both residential and industrial use. Legal
proceedings have also taken place between Southern States over the right to use water. The
requirement of a wet scrubber to control SO2 would create additional stresses over this water
resource since an estimated 45,000,000 additional gallons per year of fresh makeup water would
still be required even with recycling and treatment.

Response: Because of the requirements for HCl control on existing and new kilns under the
NESHAP, most kilns will be equipped with wet scrubbers or lime injection for the control of
HCl. As a result, new kilns subject to the revised NSPS will have their SO2 emissions
incidentally controlled. None of the cost of the scrubbers will be attributable to the final NSPS
amendments. Even in the absence of the NESHAP, EPA considers wet scrubbers and lime
injection to be BDT and justified for the control of SO2 emissions.

Estimates of scrubber costs under the final NESHAP were based on a review of various reported
capital costs, fixed costs and variable costs for limestone, water, power and gypsum (Andover,
March 10, 2009). Based on comments received on the costing methodology, cost factors were
revised which resulted in an increase in estimated scrubber costs. In particular, gas flowrates and
capital cost estimates were found to underestimate costs. As a result, gas flowrates were
adjusted, along with other factors dependent on gas flow rates, for example water usage, with the


                                                 46
result that estimates of capital costs were substantially increased (Andover, September 25, 2008;
Andover, March 10, 2009; Andover, February 26, 2010; Andover, May 6, 2010).

Regarding the commenter‘s concern over insufficient water availability for scrubbers, other
options for reducing SO 2 emissions include dry lime injection as well as utilizing fuels and feed
materials with low sulfur content to the extent practical.

Comment: One commenter (75) states that the energy impacts of wet scrubbing are significant.
In EPA‘s scrubber cost analysis, the power requirement for a typical scrubber on a 1,200,000
tons/year plant is over 1,500 kW, or 10 kWh/ton of clinker. This additional electricity demand
represents not less than a 20 percent increase over the power required for clinker production in a
modem cement kiln (around 50 kWh/ton of clinker). Additionally, this will lead to the formation
of an additional 8,850 tons per year of carbon dioxide.

Response: EPA is aware of the increased energy demand associated with the additional control
that will be installed as well as the increase in CO 2 emissions that will result from the increase in
energy demand. These were estimated as part of the analysis of the impacts associated with the
final rules.

Comment: One commenter (75) states that the proposed SO 2 limit would require wet scrubbing
at more facilities than the one in five estimated by EPA. A review of the RBLC shows five kilns
with permitted limits above the proposed NSPS limit, which would require wet scrubbers under
the proposed rule. EPA also asserts that most new kilns will be located at sites with low sulfur
content in limestone or at greenfield sites but offers no data to support this claim. In reality, a
company faces significant hurdles to opening new plants and quarries at greenfield sites. By
overlooking reconstructed or modified kilns at existing sites with higher levels of sulfur, EPA
will be subjecting a greater number of kilns to wet scrubbing in order to meet the proposed limit
leading to significantly greater economic, environmental, and energy impacts.

Commenter 75 states that the value chosen to represent moderate uncontrolled SO 2 emissions,
1.3 lb/ton of clinker, is based on an average of data points collected no more recently than 1996.
While EPA has not provided back up for these data in the rulemaking docket for this rule, the
commenter states that it is reasonable to expect that if the average value is 1.3 lb/ton, a number
of the data points would fall above this value and the proposed limit of 1.33 lb/ton. Although
EPA has indicated that the facilities with moderate uncontrolled emissions would not need
controls, it is likely that a number of sources in the ―moderate‖ category would require controls.
This is reinforced by the RBLC review, which shows a larger than expected number of kilns
above the proposed limit. EPA indicates that the proposed limit was set to ensure that kilns with
high uncontrolled SO 2 emissions meet the typical standard of BDT. However, the commenter
believes that EPA based the proposed limit on data that are not representative of new, modem
kilns, and thus the record misstates the costs and impacts of the proposed limit. If EPA intended
to target only those facilities with high uncontrolled SO2 emissions, and not the facilities with
moderate emission levels, the commenter suggests that EPA establish the new limit at the upper
bound of the source group with moderate uncontrolled emissions. An SO2 emission limit of
approximately 4 lb/ton would still require that facilities with uncontrolled emissions at 13 lb/ton
install wet scrubbing, while not imposing the economic, environmental, and energy burdens on
facilities with moderate uncontrolled emissions. The moderate emissions group of p lants would


                                                  47
have to install dry lime injection. An NSPS limit of 4 lb/ton will allow other new kilns similar to
those listed in the RBLC to meet the NSPS with dry lime injection, recognizing that those units
are still likely to go through a BACT or LAER review that could result in a tighter limit on a case
by case basis.

Response: As discussed in a response to a previous comment, we have estimated that most
existing and new kilns will install wet scrubbers or dry lime injection systems in order to comply
with the HCl emission limits in the final NESHAP. We have revised our estimates of
uncontrolled SO2 emissions based on kiln type and location. These impacts are summarized in
the preamble.

7.3    Economic
Comment: One commenter (64) objects to EPA‘s assumption that the proposed amendments to
the NSPS would have little or no economic impact because of controls that will be required
anyway under state requirements, including BACT or LAER requirements resulting from NSR.
Because of the definitions of ―modification‖ and ―reconstruction‖ as applied to NSPS, a cement
manufacturing facility may be considered ―modified‖ or ―reconstructed,‖ and therefore subject to
the revised NSPS, even when the activity that constitutes a ―modification‖ or ―reconstruction‖
results in little or no increase in actual emissions. Under these circumstances, state regulations
may not impose any particular control technology requirement (such as BACT), and state
permitting authorities may not require (and may not even have authority to require) emission
limitations that would be equivalent to the proposed amended Subpart F limitations.

Response: As explained in the preamble and in other comment responses, cement kilns may
adopt measures so that their hourly emissions of the NSPS pollutants do not increase, so that
such kilns are not ―modified‖. In light of these available measures, EPA is not adopting separate
NSPS for modified kilns.

Comment: Commenter 64 states that EPA is proposing to establish PM emission limitations that
are at the margin of the performance of the identified technology at existing best performer
cement plants which will require new and modified cement plants to install even more efficient
control technology than that in use at plants subject to the current NSPS. EPA should e valuate
the costs and emission reduction benefits of those proposed PM emission limitations, rather than
just incorrectly assuming the costs away.

Response: As noted in other responses, EPA does not believe there are any costs under the
NSPS for meeting the PM standard, since new kilns will be required to meet the same standard
under the NESHAP. Modified kilns are subject to the PM limits under the NESHAP. We have
estimated that few kilns will install additional controls just for PM but are likely to reduce their
PM emissions as a result of other controls necessary under the NESHAP.

Comment: Commenter 64 states that there are numerous specific costs that EPA has ignored or
assumed away and that could constitute a significant additional cost burden. For examp le, EPA
has not given adequate consideration to disposal costs for the scrubber sludge, scrubber
wastewater (blowdown), and additional cement kiln dust that would be produced as a result of
the proposed NSPS. EPA has not paid sufficient consideration to ammonia costs, either, which


                                                 48
have risen dramatically in the past year and can be expected to continue to rise. The commenter
attached details on these additional cost considerations which EPA must take into account.

Response: See impacts section of preamble of final rule.

7.4      Multipollutant
Comment: Several commenter (59, 60, 63) state that the full-scale SCR installations on cement
kilns in Europe and the experience with SCR worldwide on coal- fired power plants, incinerators,
and other facilities have demonstrated the ability of SCR to greatly reduce NO x emissions and to
simultaneously reduce emissions of other pollutants, including many highly toxic ones. In
addition to NO x reduction capabilities, there are a number of emission reduction co-benefits
associated with the installation of SCR, including:

      (1) Destruction of the other pollutants, e.g., ozone inducing VOCs;

      (2) Reduction of air toxics such as dioxin and furan and benzene;

      (3) Facilitating the removal of mercury (Hg) by catalytic oxidation; and

      (4) Minimization of formation of fine PM by NOx and ammonia control.

Response: EPA is aware of and agrees with the commenters that there are Multipollutant
benefits associated with the use of SCR in addition to the control of NOx . But as explained in
previous responses, at this time EPA does not consider SCR to be adequately demonstrated for
US portland cement kilns.




                                                  49
                                     8      Miscellaneous
8.1    Proposed Rule
Comment: One commenter (56) states that the NSPS is not fair to cement plant employees and
will negatively affect pay raises.

Response: As part of our analysis of economic impacts, we are aware that certain marginal
cement plants may choose to shut down some kilns rather than spend the money to upgrade
them.

Comment: One commenter (66) states that the NSPS is well reasoned. The technology proposed
(SO2 for scrubbers, fabric filters with membrane filters for PM, and SNCR for NO x ) are proven
and available. The option for CEM for PM makes sense. Changing the standards to per ton of
clinker also makes sense, so companies that are inefficient in their material use are not rewarded.

Response: EPA acknowledges the comment.

Comment: One commenter (67) states that in §60.62(d) and §63.1356 {NESHAP Subpart LLL -
Portland Cement Manufacturing}: The proposed language states that if a pollutant is subject to
emission limits or requirements that the most stringent requirement in Title 40 must be complied
with, and the source is exempt from the less stringent requirement in Title 40. This requirement
appears to be aim at an overlap of requirements between NSPS Subpart F and NESHAP Subpart
LLL. The PM and opacity requirements in NESHAP Subpart LLL (for existing units only) are
identical to the PM and opacity requirements for units currently subject to NSPS Subpart F. The
commenter understands the intent to ensure adequate environmental protection while not
overlooking inconsistencies between rules; however, if there are requirements which are
different between the rules, then the rules should specifically identify which requirement should
be used. By identifying the rule which supersedes the other, EPA provides clarity and
consistency to state/local agencies and the regulated industry.

Response: Indicating that the most stringent provision must be complied with is the most
efficient and direct way to address this issue.

Comment: One commenter (67) states that in §60.63(b)(2)(ii), (n), (n)(1), and (n)(5) {ESP
monitoring}, the proposed language references "paragraph (o)". There is no paragraph (o) in this
section of the subpart. The references should be changed from "(o)" to "(n)." In §60.63(c), the
language should change from "modified on or before June 16, 2008" to "modified after August
17, 1971, but on or before June 16, 2008." It could be interpreted as requirements for units that
commence construction or were reconstructed or modified prior to August 17, 1971. This
language change would be consistent with the language proposed in other requirements in this
subpart.

Response: The provisions regarding ESP monitoring no longer apply.

Comment: One commenter (70) states that the vacated Clean Air Mercury Rule (CAMR) has
had a significant impact on our ability to reduce mercury emissions expeditiously and we now



                                                50
must wait on a maximum achievable control technology (MACT) standard for existing coal fired
utility boilers. Commenter 70 urges EPA to address mercury emissions from cement kilns now
by adopting a sufficiently restrictive MACT standard for these units as part of its pending
portland cement reconsideration.

Response: EPA is promulgating amendments to its NESHAP for portland cement manufacturing
facilities that will greatly reduce mercury emissions.

Comment: One commenter (70) states that many areas in the United States are struggling to
comply with the National Ambient Air Quality Standards for ozone a nd fine particulate matter
(PM2.5 ). All proposals for NSPS should be reflective of what appropriate controls can be
implemented to minimize these pollutants or their precursors.

Response: The final amendments to the NSPS and NESHAP will reduce PM2.5 emissions
although the extent of the reduction is not known.

Comment: One commenter (81) states that it seems that the draft language of the proposed
standards for new kilns and clinker coolers under §60.62 (a) (2) and (b) (2) may not be clear with
respect to indicating the that the opacity standard would not be applicable for new kilns and
clinker coolers constructed, reconstructed, or modified after the date of publication of the
proposed rule in the Federal Register. Commenter 81 reads these sections, as proposed, as
continuing to require the opacity standards except for kilns or clinker coolers constructed,
reconstructed or modified after August 17, 1971, but on or before the date of publication of the
proposed rule in the Federal Register that use a bag leak detection system, ESP predictive model,
or a PM continuous emission monitoring system.

Response: EPA is requiring the use of PM CEMS on all kilns and clinker coolers and is omitting
the opacity requirements for these sources.

8.2    Technical Support Document
Comment: One commenter (60) further examined the ―Technical Support Document for
Portland Cement New Source Performance Standards Review‖ prepared by EPA and posted in
the Cement NSPS docket as Document No. EPA–HQ–OAR–2007–0877-0049. Commenter 60 is
interested in this document because much of the information contained therein was derived from
Department responses to EPA and contractor inquiries. The commenter recommended additional
caveats and amendments, including more recent stack test results and continuous emissions
monitoring system (CEMS) data and European experience with SCRs, will further support
EPA‘s proposed NOx limit.

Response: All documentation that was used in the development of the final regulations will be
posted in the rulemaking dockets for the NSPS and the NESHAP. However, they may not all be
contained within a single technical support document.




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