been adjusted by reasonable statistical methodologies to account for
variability. See IV.A.1.f of this preamble, responding to the argument
that measurement by means of a CEM makes the standard more stringent.
Moreover, the PM standard reflects performance of fabric filters with
membrane bags, which are known to perform independent of inputs and to
have relatively small operating variability. 72 FR at 54879 (Sept. 27,
2007); 70 FR at 59449 (Oct. 12, 2005).
    Consequently, for each HAP, EPA is assessing sources' performance
over time in a reasonable manner and is not ignoring their operating
variability.
    Comment: Industry commenter 2844 also stated that EPA adopted a
floor setting methodology that is based on using lowest reported
emission results with minimal variability adjustments to estimate
emission control achieved in practice by best performing sources. EPA
considered test-to-test variability, but did not consider the inherent
variability due to raw materials, product mix, fuels, operating
conditions and plant types. The industry commenter stated that EPA has
not evaluated or validated whether its methodology accurately estimates
emissions control achieved in real world circumstances at sources.
    Response: This industry comment is inaccurate on a number of
counts. First, the statistical methodology used to estimate variability
depends on the distribution of data to which the formula is applied.
Any variation in that data--be it due to differences in raw material
concentration, fuel composition, or device operation--is thereby
accounted for. Indeed, the data base for mercury consists virtually
entirely of raw material and fuel mercury levels from which emissions
are projected on a worst case, mass balance basis (since virtually no
kiln controls its mercury emissions). Consequently, EPA's methodology
does evaluate variability of inputs as well as product mix, fuels,
operating conditions, and does not just evaluate control device
operating variability as the commenter maintains. Second, for mercury
and THC, EPA gathered data over time, as explained in the preamble and
in the previous response. Third, for mercury, industry had ample
opportunity to provide longer term sampling data and (with a few
exceptions, which EPA evaluated and accepted) did not do so. Fourth,
use of a pooled variability factor (which for mercury includes the
reasonably estimated long-term intra-quarry variability of the two best
performers extrapolated to all other sources in the MACT pool) further
accounts for long term variability.
    Comment: Industry commenter 2844 stated that EPA cannot evaluate
floors using methodologies that focus exclusively on technology if the
resulting standards do not reflect actual average limitation[s]
achieved (Brick MACT, 479 F.3d at 882). The industry commenter
concludes that Brick MACT requires EPA to address the role of non-
technological factors that impact emissions in setting floors and EPA
must develop a methodology that accurately estimates the actual
emissions achieved in practice by the best performing sources under a
variety of operating conditions, taking into consideration testing and
technological and non-technological variability. As proof that EPA
failed to properly account for sources' variability in setting the
standards, the industry commenter (and industry commenter 2845)
included a chart purporting to demonstrate that the kilns comprising
the pool of best performers for each HAP could not themselves meet the
proposed standard.
    Response: EPA believes that its methodology reasonably estimates
the variability of the best performing sources, taking into account
both technological (emission control device) and non-technological
(varying inputs) variability. EPA disagrees that the record shows that
the kilns comprising the MACT pool for each floor cannot themselves
meet the promulgated standards (see previous response). In fact, for
each pollutant, the record indicates that every kiln in the MACT pool
(not just the kilns below the average of the best performers) would be
in compliance. See section IV.A.1.b above.
    Comment: One industry commenter (2845) stated that case law and
policy dictate that EPA must consider variability in establishing MACT
standards, and the approach used by EPA in Prevention of Significant
Deterioration (PSD) permitting should also apply in establishing MACT
standards. To evaluate the emission limits achieved by existing
sources, EPA is required to develop methodologies for estimating the
variability associated with all factors that impact a source's
emissions, including process, operational and non-technological
variables (see Nat'l Lime Ass'n v. EPA, 627 F.2d 416, 443, DC Cir.
1980). While Courts have affirmed EPA's authority to choose a
methodology designed to estimate emissions in setting the MACT floor,
the Courts have also made clear that EPA's method must allow a
reasonable inference as to the performance of the top 12 percent of
units (Cement Kiln Recycling Coalition v. EPA, 255 F.3d 855, 862 (DC
Cir. 2001)) (citing Sierra Club v. EPA, 167 F.3d 658, 663, DC Cir.
1999). Accordingly, the Court of Appeals for the DC Circuit has stated
that EPA must show not only that it believes its methodology provides
an accurate picture of the relevant sources' actual performance, but
also why its methodology yields the required estimate (Cement Kiln
Recycling Coalition, 255 F.3d at 862).
    Response: EPA agrees that sources' variability should be accounted
for both in determining which sources are best performers and what
their achieved performance is. EPA also believes that it has reasonably
accounted for sources' variability here, including both variability in
inputs and operating variability.
    Comment: Industry commenters 2844, 2845, and 2916 objected to EPA's
interpretation of CAA Sections 112(d)(2) and 112(d)(3) and the Brick
MACT opinion (Industry commenter 2845 provided a white paper as an
appendix to their comments for the HWIMI MACT proposal, dated December
01, 2008.). The paper, titled ``Implications of the Brick MACT Decision
on EPA's Discretion in Setting MACT Floors,'' discusses variability at
some length. The paper's main points were:
     The Agency has chosen to focus on setting MACT floors
based on lowest

emitting sources derived from limited test results that are not
appropriately adjusted to account for stack test variability.
     The Brick MACT decision holds that EPA must base MACT
floors on achieved emissions control rather than control technology,
but it does not require EPA to ignore operational variability in
determining those floors. Variability methodologies must reasonably
estimate or predict emissions or variability through a demonstrated
relationship between the data used and the performance intended to be
estimated. Non-technological factors (i.e., raw materials and fuel)
must be considered in determining emission control achieved by best
performers. It is within EPA's discretion to define the best performing
sources.
     EPA should estimate variability in determining achieved
emissions. The Agency can and must seek appropriate data from regulated
entities and other stakeholders, and to develop appropriate fact-based
estimating methodologies on the data available.
    Response: EPA largely agrees with these general points and believes
that it has adhered to these concepts in the final rule. EPA has also
implored, and in many instances, compelled (through section 114
letters) industry to provide additional data to better gauge sources'
performance.
    Comment: A number of commenters including 2844 and 2845 argued that
EPA should use an Upper Tolerance limit (UTL) rather than Upper
Predictive Limit (UPL) statistical methodology to assess variability.
    Response: EPA disagrees. An Upper Tolerance Limit is ordinarily
utilized for large data sets and is intended to assure that predicted
values are lower than a single highest observation. R. (Gibbons,
Statistical Tolerance Limits for Ground-Water Monitoring,Vol. 29, No.
4, Ground Water, July-August, 1991) This methodology is intended to
produce values that do not underestimate variability but for this
reason tends to produce inflated predictions when applied to data sets
containing multiple observations, which is the case for the MACT pools
for each HAP in this rulemaking. This methodology would therefore
overestimate performers' variability as applied in this rulemaking and
EPA is therefore not utilizing it. EPA understands that they no longer
regard use of UTL statistical methodology as necessitated here.
    Comment: Several industry commenters (2832 and 2859) opposed the
approach taken by EPA in its beyond-the-floor MACT analysis. Among
other things, EPA failed to consider the creation of incremental
greenhouse gas emissions associated with the construction, installation
and operation of new emissions control equipment, and the minimal
incremental environmental benefit associated with those controls. Also,
EPA failed to consider the cost of carbon credit purchases by the
industry.
    Response: In all cases we declined to adopt beyond-the-floor
standards based on consideration of costs, technical feasibility, and
consideration of nonair environmental impacts. Evaluating other
disbenefits for an option already rejected would have no purpose.
    Comment: Many industry commenters (2830, 2845, 2846, 2855, 2858,
2859, 2879, 2887, and 2890) stated that CEMS are not a proven
technology and should not be required to determine compliance.
    Industry commenters 2588, 2844, 2845, 2846, 2858, and 2890 stated
that EPA has no data showing that mercury CEMS are feasible on cement
kilns and that emissions from cement kilns will likely be outside of
the range of the current CEMS technology. The industry commenters
stated that EPA must evaluate mercury CEMS through long-term field
trials at cement plants in accordance with the proposed performance
specifications and quality assurance procedures before imposing this
regulatory requirement. The industry commenters proposed a mass-balance
approach for monitoring, which is accurate and was used by EPA in
setting the mercury standard.
    Industry commenter 2855 stated that mercury sorbent trap monitoring
systems have not been evaluated through long term field trials at
cement plants in the United States (U.S.) in accordance with the
proposed performance specifications and quality assurance procedures,
so the reliability and performance of these measurement systems and the
adequacy of the technical specifications cannot be determined.
    Industry commenters 2855 and 2900 disagreed with EPA's
interpretation of the operating experience with mercury CEMS in
Germany. The industry commenters stated that mercury CEMS are
inaccurate and difficult to maintain. Further, mercury CEMS operating
in Germany are subject to monitoring regulations that are different
than the U.S. regulations and are used in a different regulatory
context than that proposed by EPA. The monitors used in Germany, or
those available from other European or Asian manufacturers were not
able to demonstrate acceptable performance in the Electric Power
Research Institute (EPRI) Trimble County Mercury CEMS study.
    Industry commenter 2855 stated that there is no legitimate
technical basis on which to establish detailed performance
specifications or quality assurance (QA) requirements for these CEMS.
There is no legitimate technical basis to conclude that these CEMS
could meet such requirements over any extended period when installed
and operated at a cement plant. The industry commenter recommended that
EPA evaluate the performance of mercury CEMS at cement kiln systems and
acquire the information necessary to serve as the basis for technical
specifications and requirements. After such information is available
and analyzed, EPA should re-propose appropriate and demonstrated
performance specifications and quality assurance procedures for mercury
CEMS to monitor kiln and kiln/in-line raw mill mercury emissions.
    Industry commenter 2855 disagreed with EPA's interpretation that
mercury CEMS can be applied to the cement industry based on successful
use on utility boilers. The commenter evaluated the following issues:
    Number of Installations in the Utility Industry--There are 35-40
continuous mercury monitors (CMMs) installed and certified to date (not
yet with a National Institute of Standards and Technology (NIST)
traceable calibration source).
    NIST Certification--In mercury CEMS certification requirements
outlined in Performance Specification (PS)-12A, it states that all
calibration and span gases must be NIST certified. The draft protocols
were just released by NIST in July 2009. The major vendors of mercury
CEMS are just now advertising NIST-certified calibration sources.
Therefore, none of the mercury CEMS that have been previously installed
are certified. NIST does not currently directly certify oxidized
mercury calibrations. The Interim EPA Traceability Protocols now in
place provide for certification of evaporative generators by
certification of the individual components of the calibrator.
Therefore, the language used in Section 7.0 that refers to a NIST trace
oxidized mercury calibrator needs to be clarified or changed.
    Difficulties Encountered in the Utility Industry--The industry
commenter gave examples of power plants' difficulties with mercury
CEMS.
    Installation on Wet Stacks--Installing a mercury CEMS on a wet
stack can result in problems: Plugging, corrosion, and buildup of
solids. Although wet scrubbers are not currently common in the cement
industry, under the proposed rule, they may be required to

a greater extent, and many of these same problems with mercury CEMS
potentially could occur for the cement industry as well.
    Data Output Requirements--There is no need for dry basis
measurements under the proposed rule and the language in either Subpart
LLL should be included to provide an exemption from this requirement
for cement plants or PS-12A should be revised. This language needs to
be clarified by EPA.
    Cost--The industry commenter provided information about CEMS costs,
estimating that if mercury CEMS were installed on all non-waste-burning
U.S. cement facilities, the total capital costs would be approximately
$45 million, with annual operating costs being about $25 million.
    Industry commenter 2901 stated that CEMS should not be used as a
compliance method for cement plants for the following reasons:
    EPA reported in 1997 on an experiment where CEMS were installed on
a cement kiln burning hazardous waste. The Agency found substantial
problems regarding mercury CEMS measurement accuracy and precision,
deciding not to require Mercury CEMS at cement plants. The industry
commenter stated that the primary issue is whether there is a NIST
traceable standard that can be used to calibrate the unit. Because
compliance is based on the production rate and on using a 30-day
average, it is difficult to know what range to calibrate these units.
    The reliability of CEMS on cement kiln stacks has not been
demonstrated in the U.S., where standards and requirements are
different. Demonstrations in the U.S. at coal-fired power plants have
different conditions than those at cement kilns.
    There is no legal imperative for EPA to require CEMS. Under the
CAA, EPA's monitoring requirements must provide a reasonable assurance
of compliance with emission standards Sierra Club v. EPA, 353 F.3d 976,
990-991 (DC Cir 2004) (Copper Smelters) citing Natural Res. Def.
Council, Inc. v. EPA, 194 F.3d 130, (DC Cir 1999).
    Response: Several commenters questioned the applicability of
current continuous instrumental gaseous mercury CEMS technologies to
cement kilns. Several commenters also raised technical issues about
specific performance criteria in Performance Specification 12A (PS 12A)
for gaseous Hg CEMS and expressed concern as to the availability of
National institute of Standards and Technology (NIST) traceable Hg gas
standards. NIST has recently completed certification of a ``NIST
Prime'' elemental mercury gas generator at concentrations of 41, 68,
85, 105, 140, 185, 230, 287, and 353 [micro]g/m\3\ and mercury gas
generator vendors may now submit elemental mercury gas generators for
certification to serve as ``Vendor Primes''. Therefore NIST traceable
mercury gas standards can now be made available in concentrations that
exceed the equivalent mass standards for both existing and new kilns by
between one and two orders of magnitude, thus providing the capability
to accurately report excursions well beyond either standard. We have
provided responses to the comments on specific performance criteria
regarding PS 12A in the response to comments document, and in several
instances PS 12A has been revised in response to those comments. The
Agency believes that the now revised PS 12A is fully capable of
properly measuring the performance of gaseous Hg CEMS in many
applications, including cement kilns.
    Regarding the applicability of the current commercially available
gaseous Hg CEMS to cement kilns, and to wet or high moisture stacks in
particular, we have considered the potential physical and chemical
characteristics of such kiln stacks and does not consider them to be
substantively different from those of other source categories,
particularly utility boilers, where technical solutions have been
deployed to enable the successful application, certification, and
operation of gaseous Hg CEMS. One of several U.S. Hg CEMS manufacturers
advises they have now installed approximately 400 Hg CEMS units on
coal-fired power plants to meet regulatory requirements, including some
with flue gas desulfurization systems with the higher stack gas
moisture levels typical of these systems. These installations have
included performance guarantees for system certification and the
manufacturer also indicated a willingness to guarantee the performance
of their units on cement kiln stacks.
    We recognize that each source will experience their own particular
learning curve as with any new instrument, but if the source should
experience an apparently insurmountable problem with a particular
installation, they still have the option to either petition the
Administrator for consideration of an alternative testing approach
under Sec.  63.7(f) or to monitor Hg using a sorbent trap monitoring
system by Performance Specification 12B (PS 12B). We disagree with the
comment that PS 12 B requires further demonstration. The same
technology (Method 30B, 40 CFR Part 60, Appendix A) was successfully
used on several cement kilns in the process of collecting data to
establish the emission limits in this rule with good precision and
accuracy, and has also been widely deployed in the data collection
program for the current MACT rule development program for utility
boilers. EPA also believes that the growing body of evidence of the
successful use of Hg CEMS in the utility industry in the U.S. is
further evidence that Hg CEMS can be used in the cement kiln industry.
In addition to the knowledge regarding the use of Hg CEMS on cement
kilns in Europe, EPA is aware of two instances where Hg CEMS have been
installed on cement kilns in the U.S., with specific evidence of
successful execution of seven day calibration drift checks, linearity
(measurement error tests, as well as relative accuracy testing.
    Comment: Industry commenter 2845 stated that EPA should require
that compliance with HCl limits should be measured by periodic stack
tests. Because the HCl floors were developed from HCl stack test data,
the standard for HCl should be based on periodic stack testing. EPA
must evaluate valid data from Method 321/ASTM D6348 stack tests instead
of the data contained in Table 5 of the proposal. Using CEMS to measure
compliance effectively makes the standard more stringent than what has
been achieved by the best-performing sources. If CEMS compliance
demonstration is retained, then the limit for CEMS compliance must be
raised to reflect the added variability that will be measured by the
CEMS. While continuous measurement will capture variability of
emissions 24 hours per day, 7 days per week over the full range of
process and control system operating conditions over the life of the
plant and its associated quarry, the stack test is merely a snapshot in
time. By definition, a stack test contains no parameter related to
variability other than that obtained during the three hours of testing.
In addition to the inherent variability of HCl emissions, a CEMS
standard must also consider the inaccuracy of the CEMS as determined
(and allowed) relative to the required stack test methods, the
uncertainty of calibration standards/materials, and other factors
affecting the sampling, transport, and analysis of HCl which is a
highly reactive compound.
    Response: HCl CEMS will be measuring HCl with the same technology
that was used in the period stack tests (M321) used to set the
standard. An allowance for variability has been built in through the
process of setting the standard, including setting the standard based
on the 99th percentile UPL and increasing the

standard to the practical quantitation limit of the analytic method.
    Comment: Two industry commenters (2845 and 2859) said that EPA has
not promulgated any regulations requiring PM CEMS at any source
category due to its inability to address fundamental technical and
policy issues and must resolve these issues through rulemaking before
requiring PM CEMS at any cement plants. Furthermore EPA has not
performed a legitimate technical analysis of emissions variability and
compliance determination uncertainty to allow the use of PM CEMS for
determining continuous compliance with a PM limit at cement plants.
    The use of PM CEMS in Europe and other countries does not
constitute a valid basis for application of PM CEMS at cement plants in
the United States. Light scattering, light transmission, and extractive
beta attenuation instruments are all inferential measurement devices
and a correlation must be established to relate the device output to
the actual PM concentration, then the accuracy and bias of the
reference test and the uncertainty of the statistical correlation, as
well as the stability of the correlation must be considered. Under the
German TUV and the European monitoring standard (EN 14181) these
uncertainties are considered; emissions are not considered to exceed
the allowable limit until the lower bound of the confidence interval
and/or tolerance interval exceeds the emission limit; emission
standards may contain different averaging periods requiring different
levels of conformance; and when a problem is encountered, the emphasis
is on resolving the emission problem rather than direct enforcement and
collection of financial penalties. All of these considerations place
the European monitoring program in an entirely different regulatory
context than the proposed PM monitoring requirements.
    Response: We reject the industry commenters' assertions that PM
CEMS have not been required via rulemaking because of unresolved
fundamental technical or policy issues. Concerns about PM CEMS were
identified and addressed prior to the January 2004 publication of
Performance Specification 11 and Quality Assurance Procedure 2 for PM
CEMS (69 FR 1786, January 12, 2004). As mentioned in that rule's
preamble, ``* * * we believe that the PM CEMS field demonstrations
completed to date encompass a range of operating conditions and
emission characteristics * * *'' including those exhibited by sources
such as cement kilns.
    Moreover, we disagree with the assertion that our analysis of PM
emissions variability is not legitimate, yielding an overly-stringent
PM emissions limit. The PM limit is based on our analysis of PM
emissions from test data, adjusted from an hourly to a 30-day averaging
period and further adjusted for variability. As mentioned in the
preamble to the Credible Evidence Rule (62 FR 8314, February 24, 1997),
we have addressed and continue to address concerns about perceived ``*
* * limited number and distribution of test runs and the inherent
variability in levels of emissions * * *'' by a number of approaches,
including changing emissions averaging periods.
    Certainly a statistically-based adjustment to account for emissions
variability, and which, in this case, increases the numerical value of
the standard (and its longer averaging period) by fifty percent, does
not make the standard more stringent.
    Finally, the continuous collection of data used to assess
compliance with this twice-adjusted standard does not create a limit
more stringent that otherwise allowed. As discussed in the preamble to
the Credible Evidence Rule, ``* * * continuous monitoring of the
standards (has) no effect on the stringency of the standard * * *'' (62
FR at 8326, February 24, 1997).
    Rather, consistent with the rulemaking description process given in
Section 4.1.1 of the Credible Evidence Rule Response to Comment
Document, we used our ``* * * judgment, based on available information,
to establish emissions standards at (appropriate) levels where the
standards can be met on a continuous basis by a well operated and
maintained source that employs best demonstrated technology * * *''
\44\
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    \44\ See Section <IP_ADDRESS> of the Credible Evidence Rule Response
to Comment Document, available at http://www.epa.gov/ttncaaa1/t1/
fr_notices/certcfin.pdf.
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    Comment: Two industry commenters (2845 and 2859) had the following
comments concerning technical issues associated with application of PM
CEMS. EPA has not addressed nor resolved the primary technical issues
limiting the effective application of PM CEMS at cement plants
including:
     Inability to generate a sufficiently wide range of PM
concentrations to establish an acceptable correlation (i.e.,
calibration),
     Accuracy and precision limitations of reference method at
PM levels necessary to generate valid correlation, and
     Subsequent changes in effluent matrix and/or PM (i.e.,
particle size distribution, refractive index, particle density, etc.)
that influence the stability of the correlation and hence, the
relationship between the output of the inferential measurement device
relative to actual PM concentration.
    Valid PM CEMS correlations cannot be established for PM CEMS at
cement plants due to limitations of process operation and control
equipment in conjunction with the proposed emission limitation. The
requirements in Appendix A, PS-11 for the PM CEMS correlation and in
Appendix F, Procedure 2 do not provide a sufficiently reliable means to
determine compliance with emission limitations.
    Response: We have not identified problems cited by the commenters
at existing installations. In fact, PS-11 and Procedure 2 are working
well. We note that PS-11 has several features to address correlation
issues. For example, PS-11 provides for the addition of a zero point,
which enhances the ability to provide a calibration. We note that PS-11
has several features to address correlation issues due to any
limitations of process operation and control equipment. PS-11 provides
for the addition of a zero point. For example, if control equipment
operations cannot be varied adequately to achieve higher PM
concentrations, resulting in a cluster of data points at a very low
level and making it difficult to achieve PS-11 criteria, then an
artificial data point may be selected at zero that allows the
correlation curve to be developed that meets the correlation criteria.
It also strongly suggests the use of paired trains to insure that
accuracy and precision is obtained. Changes in the effluent matrix
could potentially be a problem with light scattering technologies but
this has not been shown to be a problem with existing installations.
This would not be a problem with beta attenuation monitors. Factors
that influence the stability of the correlation are addressed in
Procedure 2 (40 CFR, Appendix F). Procedure 2 describes the required
audits to insure that subsequent measurements are stable and within
acceptable limits, thereby ensuring reliable and stable compliance
measurement data.
    Comment: Two industry commenters (2845 and 2859) had the following
comments concerning PS-11 and Procedure 2. The requirements at Sec.
63.1349 for PM CEMS are incomplete and ambiguous and EPA has failed to
specify important QA frequencies and other information relevant to the
implementation of PM CEMS in accordance with PS-11 and Procedure 2. The
proposed Subpart LLL revisions fail to address critical elements
including the following sections of PS-11 and Procedure 2:

     PS-11 3.20, species reference method as method defined in
applicable regulations (Method 5 with 250 [deg]F filtration
temperature) but this is inadequate for low concentrations where Method
5I should be used, and is inapplicable to sources with PM that
condenses between the stack temperature (mill on and mill off, if
applicable) and 250 [deg]F where Method 17 should be used or ASTM D
6831.
     PS-11, 6.2 You must ensure that the averaging time, the
number of measurements in an average, the minimum data availability,
and the averaging period for your CEMS conform to those specified in
the applicable regulation--but none are specified.
     When using PS-11, 6.5 Your CEMS must sample the stack
effluent such that the averaging time, the number of measurements in an
average, the minimum sampling time, and the averaging procedure for
reporting and determining compliance conform to those specified in the
applicable regulation--but none are specified.
     Procedure 2, 10.3 You must conduct a response correlation
audit (RCA) and a relative response audit (RRA) at the frequency
specified in the applicable regulation * * * but none are specified.
     Procedure 2, 10.3, You must perform an RRA at the
frequency specified in the applicable regulation * * * but none is
specified.
     When using Procedure 2, 10.3(7) You must perform an RCA at
the frequency specified in the applicable regulation * * * but none is
specified.
     When using Procedure 2, 10.9 You must report the accuracy
results for your PM CEMS at the frequency specified in the applicable
regulation * * * but none is specified.
    Response: We recognize that PS-11 does not specify a reference
method; we have revised the final rule to specify Method 5 or Method 5I
(40 CFR part 60, appendix A) as the reference method. Facilities with
issues in application of these reference methods, may petition the
Administrator for alternatives or modifications under Sec.  60.8(b) or
Sec.  63.7(f). The averaging times and data reduction specifications
have been added to Sec. Sec.  60.63(c) and 63.1350(b) of the rule.
There are no specific data availability requirements, Sec. Sec.
60.63(g) and 63.1348(b) require that monitoring be conducted at all
times the affected source is operating except for periods of monitoring
system malfunctions, repairs, or quality assurance/quality control
activities. The language of the final rule has been revised to specify
the frequency of the Relative Response Audits (annually) and the
Response Correlation Audits (every three years), for specifics, see
Sec. Sec.  60.63(c)(2) and 63.1350(b)(2). Absolute Correlation Audits
are required by Procedure 2 on a quarterly basis.
    Comment: One environmental advocacy group commenter (2786) stated
that EPA should not eliminate opacity standards in the proposed rule.
The commenter stated that there are benefits to having an opacity
standard in conjunction with a particulate matter standard. Opacity
measurements can be made by anyone who is trained to measure opacity,
which can include members of the public and not just inspectors, and
opacity measurements are a cheaper method of getting more frequent
measurements.
    Response: We disagree. Given the sensitivity of the BLD and PM
CEMs, we find the opacity requirements to be redundant.
    Comment: One environmental advocacy group commenter (2898) stated
that EPA should require PM CEMS and retain the opacity monitoring
requirements. EPA is proposing installation and operation of a BLD
system, along with stack testing using EPA Method 5 conducted at a
frequency of five years for demonstrating compliance with the proposed
PM emissions limit. As an alternative, a PM CEMS that meets the
requirements of PS-11 may be used, and EPA is proposing to eliminate
the current requirement of using an opacity monitor. The proposed rule
solicits comment on making the use of a PM CEMS a requirement. The
commenter stated that EPA should both require CEMS and retain the use
of opacity monitors.
    EPA should abandon the BLD system requirement outlined in the
proposed rule and mandate the use of PM CEMS instead. The agency
previously concluded that PM CEMS is a superior monitoring technology
that can be implemented at a reasonable price. EPA has found that BLD
systems, standing alone, are inadequate to verify compliance and has
also found that continuous opacity monitors (COMS) operate as a useful
check on PM emissions and proper operation of PM CEMS.
    Providing a superior level of compliance assurance is not the only
benefit of PM CEMS. EPA has acknowledged that the assumptions to assure
compliance are fewer and less conservative (direct measure of the
standard is the top of the monitoring hierarchy), CEMS mean facilities
need to monitor only one emissions parameter to assure compliance
rather than multiple operating limits, often relevant to more than one
standard, and that the cost of installing PM CEMS technology is
reasonable.
    Response: We would support the use of multi-metal CEMS, should they
become available. We have not yet seen evidence that COMS are well-
suited for continuous compliance as are BLD or PM CEMS, so that
requiring their use as a backup system would add monitoring costs to no
special environmental benefit.
    Comment: Several industry commenters (2832 and 2859) opposed the
proposed requirement to install CEMS in order to satisfy compliance
assurance monitoring (CAM) for selected pollutants. Instead, the
commenter proposed that CAM requirements be satisfied using periodic
stack testing to the extent that stack testing is requested or required
by State air permits. According to EPA's proposal, the MACT floor for
new and existing sources in this industry will be determined by stack
testing results of sources within the MACT pool. If EPA were to
finalize a numeric emissions limitation based on this approach to
setting the new and existing MACT floors, that limitation will be based
on the same stack testing data. CEMs will have played no role in this
process. It stands to reason that compliance assurance should be based
on stack testing results, and not a CEMS data that has played no part
in this process.
    One industry trade association commenter (2916) stated that EPA can
achieve a reasonable assurance of compliance without the use of CEMS.
The requirement to use CEMS is unreasonably costly and unnecessary,
given that other reliable means of showing compliance are available for
all relevant pollutants. Raw material sampling and kiln parametric
monitoring, in conjunction with periodic testing, would work well for
THC and HCI. The sorbent trap method for mercury is a good alternative
to mercury CEMS and should be retained in the final rule. EPA should
refrain from requiring PM CEMS in the final rule. Bag leak detection
systems and parametric monitoring of ESPs are proven methods for
assuring ongoing compliance with PM limits.
    Response: We disagree. In the case of THC, emissions may change
significantly due to a process change without any advance indication.
In addition, the THC emission limits were established using data from
CEMS, and the standard itself is a 30-day average, requiring 30 monthly
measurements (only practically obtainable with a CEM). Therefore, CEMS
are the obvious

compliance assurance choice. In the case of mercury emissions, short
term test data do not necessarily reflect the long term emissions. In
addition, the performance of the available mercury controls may be
significantly affected by operational factors. To devise a test plan to
clearly establish the performance of mercury control under all
conditions would be difficult, and for that reason it would be
difficult to establish the proper control device operating parameters
and operating limits. Therefore, mercury CEMS are essential in
demonstrating continuous compliance with the mercury emissions limits.
If the facility does not have a wet scrubber, changes in raw materials,
or fuels could significantly increase emissions without any indications
unless a CEMS is used.

B. What are the significant comments and responses on 40 CFR part 60,
subpart F?

    Comment: Several State and environment advocacy group commenters
(62, 65, and 69) objected to EPA not proposing standards for greenhouse
gas (GHG) emissions under the proposed NSPS. One State 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. State commenter 62 protests this course of action, and requests
that EPA revise the proposed rule to include NSPS for GHG emissions.
    According to State commenter 62, EPA's failure to propose NSPS for
GHGs in the proposed rule violates section 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 State 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. State and environmental advocacy group
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
State and environmental advocacy group commenters state that:
     EPA is required by section 111 to promulgate NSPS for all
pollutants emitted by a regulated source category including
CO2 emission from cement plants and EPA's assertion that
section 111 does not compel the agency to regulate CO2
emissions is contrary to the Act's plain language.
     Congress has expressly directed that NSPS address the
emissions of ``any'' air pollutant, a term that plainly encompasses
CO2.
     At a minimum, in directing that NSPS be established for
sources that cause, or contribute significantly to air pollution which
may reasonably be anticipated to endanger public health and welfare,
Congress showed that it meant to require limits on emissions of any
pollutants that cause or contribute to such endangerment. Because
cement plants emit CO2 in such amounts that those emissions
significantly contribute to ``air pollution which may reasonably be
anticipated to endanger public health or welfare,'' EPA is legally
required to issue standards of performance limiting those emissions.
EPA cannot rationally assert that cement plant CO2 emissions
do not meet these criteria, and the Agency's refusal to promulgate
standards of performance is therefore unlawful.
     EPA's contention that it can refuse to regulate
CO2 emissions on the basis of interactions with other CAA
provisions is impossible to reconcile with section 111, because that
section clearly contemplates that EPA will adopt standards of
performance covering pollutants that have not previously been subject
to regulation under the Act.
     Cement plants' emissions of CO2 cause, or
contribute significantly to, air pollution which may reasonably be
anticipated to endanger public health or welfare and significantly
contribute to global climate change.
     There are existing technologies that can reduce emissions
of CO2 from cement plants. In addition to the suggested
technologies, other measures that would also have CO2
reduction benefits include shifting from 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 U.S. 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: Due to issues related to the regulation of GHGs under the
CAA, no standards of performance for GHGs were included in the proposal
and none are being included in the final amendments. Promulgating a
standard without first proposing it does not follow the accepted
process of proposal and public comment that is required of EPA
rulemakings. Also, we have not gathered the information we need on GHG
emissions and control strategies for the Portland cement industry.
EPA's decisions and plans for regulating GHG from this industry are
discussed earlier in this document (see section IV.B.1.g).
    Comment: Several private, State and environmental advocacy group
commenters (59, 60, 63, 68, 70, 71, 72) approve of the proposed limits
for NOX or believe more stringent limits are appropriate.
One private 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 a standard of no greater
than 0.5 lb NOX/ton clinker and states that SCR is an
effective and proven technology to reduce NOX emissions from
cement kilns and can reduce NOX emissions from cement kilns
by greater than 90 percent, consistent with what has been observed with
SCR in other industries. According to the private commenter, SCR can
achieve this performance with cost-effectiveness of approximately
$1,500-$3,800/ton NOX, easily within regulatory cost
thresholds for many NOX control programs. Regarding concerns
over dust and plugging, the commenter cites three recent installations
of SCR on cement kilns that show that SCR vendors can properly design
and install units which manage the dust and successfully operate for
many years. The commenter stated that numerous SCR companies believe
that they can design and supply SCR systems for NOX control
at cement plants where they will have to guarantee performance levels
in legal contracts, and thus they would be at significant financial
risk to advertise and sell an SCR system that was actually going to
fail. The effectiveness

of the technology to reduce NOX and other pollutant
emissions from cement kilns, as demonstrated by the SCR installations
on cement kilns in Europe and the numerous SCR installations on other
heavy industries like coal-fired power plants and waste incinerators,
is supported by the marketing, technical assessments, and reports
prepared by numerous experts on this subject, including: Three (3)
cement companies, five (5) SCR manufacturers, an independent blue
ribbon panel, the U.S. EPA (twice), and the European IPPC. State
commenter 68 believes that EPA's proposed NOX limit of 1.5
lb/ton clinker 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. 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. 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.
    One State commenter (60) states that the NOX emission
limit should be lowered 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 State commenter states that the
recommendations regarding PH and PH/C kilns should apply equally to
projects at greenfield sites and brownfield sites stating that many of
the advances in NOX control in the U.S. and Europe have been
made at brownfield sites whether they have involved new kilns or
reconstruction or modification of existing kilns.
    To support the State commenters recommended limits for
NOX, the commenter provided the following information and
included several supporting documents as attachments to the comments:
     A long-term value of 1.46 pounds per ton (lb/ton) of
NOX clinker was achieved with no add-on control equipment
when not accounting for slag use and 1.38 lb/ton when accounting for
slag use at TXI Kiln 5 (a PH/C kiln) in Midlothian, Texas.
     A long-term value of 1.98 lb/ton was achieved with no add-
on control equipment at Cemex Sta. Cruz (a PC/H kiln) in Davenport,
California. The project involved an improvement to an existing calciner
(commissioned in 1997) on an existing kiln to comply with an existing
NOX limitation.
     Titan America (a PH/C kiln) in Medley Florida and Giant
Cement in South Carolina where average values of 1.62 and 1.88 lb
NOX/ton were documented for new kilns with no add-on control
equipment at brownfield sites.
     The results from the existing SCANCEM (an affiliate of
Lehigh) Sk[ouml]vde PH kiln where emissions were reduced from 4.4 lb
NOX/ton (1995) by installation of a SNCR system and which
achieved 0.72 lb/ton in 2005.
     The results from the existing SCANCEM Slite PH/C kilns
where emissions were reduced from 4.0 lb NOX/ton (1995) by
installation of an SNCR system and which achieved 1.01 lb/ton in 2005.
     The results from the existing Radici Cementeria di
Monselice PH kiln where emission reductions to values as low as 0.20 lb
NOX/ton were demonstrated by installation of a SCR system.
The supplier guaranteed reduction of 90 percent and realized reductions
as high as 97 percent.
    State commenter 60 states that based on the foregoing, 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, 1 lb/ton is achievable by SNCR. Given a kiln with less
sophisticated design or particularly difficult raw materials achieving
3 to 5 lb/ton, SNCR or SCR or a combination of the two can reduce
emissions to values much less than 1 lb/ton. The commenter states that
the proposed averaging time of 30 days is a tremendous concession to
the industry. The availability of reagent injection makes it easier to
achieve the proposed standard on a 24-hour basis. The lowest permit
limit for a project under construction in the United States applies to
the Drake Cement in Arizona. The value is equivalent to 1.14 lb/ton on
a 24-hour basis. A contract was awarded to F.L. Smidth who developed
the calciner that achieves 2 lb/ton or less at TXI, Titan and Cemex as
discussed above. The limit will be achievable using an SNCR system.
    State commenter (60) states that because long wet and long dry
kilns use much more energy to make a ton of clinker, a higher
NOX limit may be acceptable for these kilns. State commenter
60 agrees with EPA's assumption that new projects triggering the NSPS
will actually result in a PH/C kiln. A project that might trigger a
prevention of significant deterioration (PSD) review at a long kiln
will probably incorporate emissions control measures to avoid PSD and a
BACT determination for NOX and SO2. The measures
to avoid PSD will also likely avoid the short-term emissions increases
that would otherwise trigger the NSPS.
    Finally, with respect to the reconstruction provisions, it is not
likely that a company will actually invest 50 percent of the value of
an existing long kiln without taking the opportunity to make it much
more energy efficient through conversion to a PH/C kiln. The State
commenter states that a separate standard for long kilns will avoid the
unnecessary relaxation of the limits applicable to PH and PH/C kilns.
The State commenter listed the following NOX reduction
technologies that have been demonstrated for long kilns and submitted
supporting documentation as attachments to the comment:
     Conversion from direct to indirect firing in conjunction
with the installation of a multi-channel (Low NOX) burner;
     Mid-kiln fuel injection (including tires);
     Near mid-kiln pressurized air injection;
     SNCR at long kilns; and
     Combination of SNCR with air injection.
    One State commenter (63) described the advances in technology for
controlling NOX emissions, especially SNCR and SCR, from
Portland cement plants, and requests EPA consider the technological
improvements and their applications when establishing NOX
emission limits. The State commenter states that EPA continues to play
a crucial role in encouraging innovation and in mobilizing supply
chains to deliver technologies that improve our air quality and
environment including the continued tightening of emission limits. This
encourages the industries such as the cement industry to work closely
with equipment and component suppliers to ensure significant reductions
in emissions in a timely and economical manner. The commenter states
that with the improved processes

that lower uncontrolled NOX emissions and with the addition
of SCR, NOX limits of 0.25-0.5 lb NOX/ton clinker
are achievable.
    One State commenter (70) supports the proposed level for new,
modified and reconstructed kilns of 1.50 lb/ton of clinker for
NOX. Facilities can meet the 1.50 lb/ton of clinker for
NOX, with SNCR alone or with SCR (either as a supplement or
as an alternative to SNCR).
    One State 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
State 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 an SNCR control efficiency
of 50 percent, a NOX emission level of 1.3 lb/ton of clinker
is achievable. As a result, cement kilns with SNCR control technology
can achieve a NOX emission level between 1.14 and 1.3 lb/ton
of clinker. However, this State commenter believes that the
NOX emission level from cement kilns can be further reduced
by utilizing SCR control technology. State commenter 71 states that EPA
dismisses the SCR technology used in Europe and concedes that some
mechanical problems were experienced in the early stages with plugging
but these problems were resolved and the system remained in service for
four years at the Solnhofen facility in Germany. According to the
commenter, waste disposal should not be an issue because the spent
catalyst could be added to the process as a source of alumina. State
commenter 71 previously conducted a Best Available Retrofit Control
Technology (BARCT) assessment for a cement plant in our area and
recommended SCR as the BARCT for this facility.
    One environmental advocacy group commenter (72) states that the
NSPS emission rate for NOX from cement plants should be
lowered to 0.5 lb/ton of clinker on a 24 hour rolling average because
of the ability of current plant designs to achieve very low rates of
NOX emissions without the addition of add-on pollution
controls. Currently available add-on controls can reduce NOX
emission levels below the proposed 1.5 lbs of NOX per ton of
clinker. There is a considerable operational experience with SNCR that
shows it's capable of reducing NOX emissions to 1 lb or
less/ton of clinker when combined with a modern-designed kiln. SCR has
been demonstrated in the utility industry and Europe and can further
reduce emissions.
    Response: The starting point for the NOX limit was the
emission level that could be achieved with no add-on control device for
NOX. To achieve the lowest NOX levels without
add-on controls involves the use of state-of-the-art combustion
technologies in conjunction with PH/PC kilns. In developing the
proposed limits for NOX, we used emissions data showing that
three recently permitted kilns had achieved average NOX
levels of 1.62, 1.88, and 1.97 lb/ton of clinker through the use of
combustion technologies such as low-NOX burners and staged
combustion in the calciner (SCC). We assumed that through advanced
combustion technology, an emission level of 2.5 lb/ton of clinker was
generally achievable. Following proposal, commenters supporting the
limit, commenters recommending lower limits, and commenters
recommending higher limits submitted additional data on NOX
emissions from U.S. kilns as well as kilns operating in other
countries. The data are summarized below.

                                     Table 9--Cement Kiln NOX Emissions Data
----------------------------------------------------------------------------------------------------------------
                                                                                NOX emissions
                                                                                before add-on
              Kiln                     Kiln type         Process controls     Add-on controls   control  (lb/ton
                                                                                clinker)
----------------------------------------------------------------------------------------------------------------
TXI, Midlothian, TX, Kiln 5       PH/PC..............  LNB, slag..........  None..............              1.38
 (2003).
                                  ...................  LNB................  None..............              1.46
Cemex, Santa Cruz, CA (2006-      PH/PC..............  SCC................  None..............              1.98
 2007).
Titan America, Medley, FL (2007,  PH/PC..............  SCC................  None..............              1.62
 2008).
Giant Cement, Harleyville, SC     PH/PC..............  SCC................  None..............              1.88
 (2006, 2007).
TXI Riverside, CA...............  Long Dry...........  Combustion, Process  None..............               1.5
                                  Long Dry...........  Combustion, Process  None..............               1.5
Lafarge Sugar Creek, MO (2004-    PH/PC..............  LNB, SCC...........  None..............              3.58
 2005).
Lafarge Calera, AL (2006-2007)..  PH/PC..............  LNB, SCC...........  None..............              2.06
Lafarge, Alexandria, Egypt        PH/PC..............  LNB, SCC...........  None..............              2.03
 (2007).
Lafarge, Richmond, Canada (2007)  PH/PC..............  LNB, SCC...........  None..............              2.64
Lafarge, Port La Nouvelle,        PH/PC..............  LNB, SCC...........  None..............              2.65
 France (2007).
Lafarge, Ewekoro, Nigeria (2007)  PH/PC..............  LNB, SCC...........  None..............              3.38
Lafarge, Kujawy, Poland (2007)..  PH/PC..............  LNB, SCC...........  None..............               3.4
Lafarge, Harleyville, U.S.        PH/PC..............  LNB, SCC...........  None..............              3.48
 (2007).
Lafarge, Tetouan, Morocco (2007)  PH/PC..............  LNB, SCC...........  None..............              4.07
                                  ...................  ...................  AVG...............              2.41
----------------------------------------------------------------------------------------------------------------

    The average uncontrolled NOX emissions for the listed
kilns are 2.4 lb/ton of clinker. If the result for the long dry kiln is
removed, the average is 2.5 lb/ton. This result is consistent with the
baseline NOX level used by EPA in the development of the
proposed NOX limits. To allow for variations in process,
fuel or feed, EPA selected a baseline level of 3.0 lb/ton of clinker.
    To arrive at the emissions limit for NOX, we evaluated
two add-on control technologies for BDT: SNCR and SCR. EPA agrees that
SCR is a promising technology for the control of NOX
emissions from Portland cement plants. The Agency also agrees that SCR
is an attractive control alternative in that it has the advantage of
reducing emissions of other pollutants in addition to reducing
NOX by 80 to 90 percent. However, although SCR has been
demonstrated at a few cement plants in Europe and has been demonstrated
on coal-fired power plants in the U.S., the Agency is not satisfied
that it has been

sufficiently demonstrated as an off-the-shelf control technology that
is readily applicable to cement kilns. The experience with SCR use on
coal-fired power plants in the U.S. is not directly transferrable to
Portland cement plants with the main difference being the lower dust
loadings at power plants than would occur at cement plants. (Note this
is not an issue for CEMS because they can be located downstream of the
PM controls.) The experience at European kilns showed long periods of
trial and error before the technology was operating properly. In
particular, problems with the high-dust installations and the resulting
fouling of the catalyst were problematic. This and other problems were
eventually overcome, although at one of the early facilities to add
SCR, the use of the SCR was discontinued in favor of a selective
noncatalytic reduction (SNCR) system while the facility owners and
operators gathered additional data to assess the advantages and
disadvantages of the SCR system in comparison to the SNCR system.
    State commenters also noted that it would be possible to combine
SNCR and SCR technology on the same kiln, thereby significantly
reducing the amount of catalyst required. This could reduce the problem
with catalyst fouling. We see no technical impediment to combining SNCR
and SCR technology. But at the same time we have no data on this
combined system to assess its effectiveness or potential for catalyst
fouling.
    At this time we therefore do not agree with the commenters that SCR
can be considered best demonstrated technology and as a result have not
established a NOX emission limit based on that technology.
    We determined SNCR to be BDT and applied a control efficiency for
the SNCR to the baseline uncontrolled level to determine the
appropriate NOX level consistent with application of BDT. As
discussed in the preamble to the proposed rule, SNCR performance varies
depending on various factors, but especially the normalized molar ratio
(NMR), or the molar ratio of ammonia injected to NOX- higher
removal efficiencies are associated with a higher NMR. SNCR performance
has been shown to range from 20 to 80 percent NOX removal.
At proposal we used an efficiency of 50 percent as representative of
SNCR performance on average. Since then, additional information on SNCR
performance has become available including data supplied by State
commenters as well as a 2008 report by the Portland Cement Association.
These data are summarized below. Reported removal efficiencies range
from 25 to over 90 percent. According to a 2008 PCA report, ammonia
slip occurs at molar ratios generally above 1.0. The graph below
illustrates the relationship between the ammonia molar ratio, or NMR,
and the performance of SNCR. EPA also examined the data to determine if
uncontrolled NOX emissions affected SNCR performance since
SNCR performance has been shown to improve with higher uncontrolled
NOX levels, but the data here did not show any effect
between initial NOX concentration and SNCR performance.
Using the data below, the average removal efficiency of SNCR is 60
percent. Thus, EPA believes the 50 percent removal efficiency used to
establish the NOX emission limit is a reasonable estimate of
the SNCR performance that allows for an operating margin considering
reasonable worst-case conditions that can be expected within the
industry or source category as a whole. This operating margin should be
sufficient to allow facilities where a greater than 50 percent
reduction may be necessary to meet the 1.5 lb/ton clinker limit to
increase ammonia injection to achieve greater than 50 percent reduction
without causing ammonia slip.

                                      Table 10--SNCR NOX Removal Efficiency
----------------------------------------------------------------------------------------------------------------
                                                   NOX emissions
                                                    before SNCR    NOX emissions      Removal      Ammonia molar
                      Kiln                            (lb/ton     with SNCR  (lb/   efficiency         ratio
                                                     clinker)      ton clinker)         (%)
----------------------------------------------------------------------------------------------------------------
SCANCEM Skovde, Sweden (1995,2005)..............             4.4             0.7              84           1-1.2
SCANCEM Slite, Sweden(1995,2005)................             4.0             1.0              75         1.2-1.4
Ash Grove, Durkee OR (1994 test)................            4.75             1.0   > 80 for most  ..............
Suwannee American (2008)........................    Not reported             1.4  ..............  ..............
Florida Rock....................................             3.1             1.7              47        0.1-0.65
                                                             3.8             2.2              42             0-1
1...............................................             7.0             3.2              55             0.7
2...............................................             4.3             3.0              30             0.7
3...............................................             4.6             2.3              50             0.7
4...............................................             4.0             2.0              50         0.6-0.7
5...............................................             3.8             2.9              25  ..............
6...............................................             4.0             2.4              40            0.25
6...............................................             4.0             2.0              50             0.5
7...............................................             3.4             1.7              50             0.5
7...............................................             3.6             0.9              75             0.8
7...............................................             3.2             0.6              81               1
8...............................................             5.0             0.4              92         1.0-1.2
8...............................................             5.0             1.1              78         1.0-1.2
9...............................................  ..............             0.9           80-85         1.2-1.4
----------------------------------------------------------------------------------------------------------------
AVG.............................................             4.2             1.7              60  ..............
----------------------------------------------------------------------------------------------------------------

[GRAPHIC] [TIFF OMITTED] TR09SE10.004

    Comment: Several industry 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 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. According to the industry commenters,
different factors can influence NOX 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 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 NOX emissions; however, in cases where the
type of fuel(s) used dictates the need for a separate calciner (such as
may be applied to utilize waste materials), NOX emissions
will be higher. In addition, sometimes a new project will consist of
upgrading an existing pyro system. In many of these cases the layout of
the existing equipment is such that it cannot be modified to perform as
well as a brand new calciner system, and will therefore have higher
NOX emissions;
    (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 NOX emissions is not the same for all systems,
especially for an existing pyro system that has been upgraded (due to
potential lack of an optimum injection point) or a very large pyro
system (due to lack of optimum mixing of ammonia and preheater gas).
    One industry commenter (75) states that although the removal
efficiency of SNCR can theoretically be improved by increasing the
quantity of ammonia injection, there is a practical limit to this
approach. As ammonia injection rates increase, the potential formation
of a secondary plume due to ``ammonia slip'' increases. In addition,
sulfur in the raw materials results in SO2 and
SO3 in the exhaust, which decreases the efficiency of
ammonia injection and leads to operational issues such as solids
accumulation and plugging downstream of the SNCR. As the industry
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, industry commenter 75
would need a control level of at least 70 percent to meet the proposed
limit of 1.5 lb/ton. Industry commenter (75) is not confident that this
can be done with SNCR. Therefore, the industry commenter recommends
that the NOX standard be established at 1.95 lb/ton, which
reflects a level of control achievable with the use of SNCR by all
facilities without introducing the negative effects associated with
pushing for high control levels.
    One industry commenter (76) states that assuming a facility is
already operating with best combustion practices (i.e., indirect fired
fuel supply systems, low primary air burners, etc.) then the
burnability of the raw mix has

the greatest single impact on NOX emissions. Statistically
speaking, most preheater precalciner cement kiln plants worldwide emit
an uncontrolled NOX emission of 3.8 to 4.2 lb
NOX/ton of clinker. With a 50 percent NOX
reduction rate from the application of SNCR technology, a controlled
emission rate of 1.9 to 2.1 lb NOX/ton of clinker could be
expected for most kilns. As such, a 1.95 lb NOX/t clinker
limit for all new kiln applications seems achievable. The issues arise
when people arbitrarily apply the 50 percent reduction potential of
SNCR to lower baseline emission numbers. (i.e., at a 3.2 lb
NOX/ton of clinker uncontrolled emission, SNCR could reduce
it to 1.6 lb NOX/ton of clinker). While this might be true
on an isolated case basis, it would be unwise to approach such a low
level for a new NSPS limit for all new kilns because of the issue of
burnability. In some cases it might be possible to reduce the baseline
NOX levels with integrated control systems, such as Multi-
Stage Combustion (MSC) installed on low NOX calciner system;
but here again, the practicality of sustaining stable, continuous
operation while simultaneously reducing the baseline NOX by
10 to 30 percent is very site specific. Industry 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 industry commenter (77) believes that under the worst-cast
combinations of raw materials, fuels and cement specifications and with
the application of SNCR technology, a controlled emission rate of 2.0
lbs of NOX per ton of cement clinker can be achieved by all
new kiln applications. However, if the kiln must incorporate a bypass
for alkalis, chlorides or sulfur, the NSPS limits must allow for
increased NOX emissions on a plant by plant basis due to the
fact that bypass amounts can be anywhere from 5 percent to 100 percent
in size.
    One industry commenter (78) states that very few kilns with alkali
bypasses would have a chance of meeting the proposed limit long-term.
One industry commenter (83) requested that EPA clarify whether the
NOX limit applies only to a kiln's main stack or both the
main and bypass stacks.
    One industry commenter (73) believes that EPA failed to
appropriately consider variables that affect uncontrolled
NOX emissions from preheater/precalciner kilns employing SCC
and LNB on an industry-wide basis. As a consequence, EPA relied upon a
limited database that did not reflect these variables and then made
assumptions reflecting an incomplete understanding of variability in
uncontrolled NOX that result from them. Industry commenter
(73) recommends that EPA revise its proposed baseline NOX
emission standard from 1.5 to 2.0 lb/ton of clinker, and allow for
adjustments of the standard upward from this value when bypasses are
used, unusually hard burning raw mixes are used, or specific clinker
types (such as oil well clinker) that require non-typical burning
methods is being produced. When bypasses, hard burning mixes and/or
clinker specifications require non-typical operational parameters, an
adjustment factor should be allowed and evaluated on a case-by-case
basis. The fact that individual kilns may be able to achieve a
NOX emission rate as proposed (or even lower rates) is not
determinative of what is an appropriate standard for the NSPS.
    Industry commenter (73) states that fuel volatility plays a major
role in NOX emission control. The uncontrolled
NOX generated in the precalciner alone can vary by as much
as 1.4 g/kg of clinker (2.8 lb/ton clinker) based on fuel volatility.
Industry commenter (73) states that modern preheater/precalciner kilns
fire approximately 55-65 percent of their fuel in the precalciner. The
nitrogen content in the fuel is the main factor affecting fuel
NOX formation. The fuel NOX produced in the
precalciner is not directly proportional to the nitrogen content of the
fuel. It also depends on the chemical form of the nitrogen in the fuel
and the volatility of the fuel. Typically, fuel nitrogen in coals used
by PH/PC kilns varies between 1.0 and 2.0 percent. This difference can
impact the uncontrolled NOX by as much as 1.5 lb/ton of
clinker.
    Industry commenter 73 states that a PH/PC kiln system uses hot
gases from the kiln to both dry and heat the raw materials prior to
calcination. The effectiveness of this system is related to the
moisture content of the raw materials and their ability to absorb heat
from the gases. If additional heat is required to dry or heat the raw
materials, gases from a separate fuel-fired furnace or the clinker
cooler are ducted to the raw mill. As a result, the moisture content of
the raw materials directly influences the NOX emission
rates. High moisture materials require additional energy to dry the
materials in the raw mill and/or preheater. This increased need for
energy contributes to the amount of NOX emitted if the
excess energy comes from burning additional fuel. Some plants may have
up to 20-25 percent moisture content in their raw mix--which results in
a 15 to 20 percent increase in the kiln's specific heat consumption, as
compared to a ``standard'' raw mix that contains approximately 5
percent moisture. This additional energy need results in the combustion
of more fuel which ultimately results in more uncontrolled
NOX.
    On NOX emissions from alkali bypasses, commenter 73
states that because the gases within the bypass are not allowed to
remain in the optimal SNCR temperature range, SNCR is not a feasible
control option for these gases. The commenter shows (in graph form in
their comments) that for a certain size kiln, bypassing 25 percent of
its kiln gases will have an incremental increase of approximately 0.42
lb/ton of clinker in the controlled NOX emission rate.
    Industry commenter 73 states that the three major kiln suppliers
require a cement company to provide detailed information on raw
materials (including moisture content), fuels, and clinker quality
specifications prior to preparing a quotation and specifying emission
guarantees. Uncontrolled 30-day average NOX emissions can
vary from less than 1.6 to greater than 4.6 lb/ton of clinker. SNCR has
been demonstrated to reduce NOX emissions from cement kilns;
however, SNCR has not been used on cement kilns for an extended period
of time. High removal efficiencies such as those stated in the preamble
(i.e., 63 percent at an ammonia-to-NOX ratio of 1.0) may
result in adverse product quality or environmental impacts that are
undesirable. In addition, the use of SNCR on larger kilns (>2,000,000
ton/yr capacity) may not be as effective due to the larger calciner
duct diameter and the inability of 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, industry Commenter 73 believes that since
NSPS is applicable to all new or reconstructed kilns, a reasonable
baseline NSPS limit taking into account typical operating conditions
and limitations stated above is 2.0 lb/ton of clinker. However, when
non-typical conditions exist (bypass, hard burning mixes, and specific
clinkers that require non-typical burning methods), an adjustment
upward from the baseline value is appropriate and should be made on a
case-by-case basis.
    Industry Commenters (64, 73) stated that the proposed
NOX limitations are substantially more stringent than the
most stringent NOX limit that applies to cement plants in
Europe, which

converts to approximately 2.5 lb/ton of clinker produced although EPA
asserts that this should be considered the ``baseline level of control
that would occur with no additional regulatory action.'' The industry
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; and (2) If
the NSPS were set at 2.5 lbs 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 lb/ton. Therefore, it would appear from EPA's
rationale that setting an emission standard of 2.5 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 industry commenter states that there may be substantial
differences between the NOX emissions that can be achieved
by new, greenfield kilns and what can be achieved by ``reconstructed,''
brownfield kilns. NOX emissions are a function of fuel type
and of raw material type, as described above. 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 industry commenter states that EPA also needs to address the
achievability of NOX limitations at cement plants that have
bypass stacks to control alkalinity because EPA has not presented any
basis for concluding that SNCR is a demonstrated technology for meeting
the proposed limits for facilities with bypass systems.
    Likewise, while EPA acknowledges that burnability may have a
significant influence on NOX emissions, EPA has not
explained how these differences are reflected in its analysis of the
BDT and the proposed new NOX limits. Cement plants with
hard-to-burn raw materials face much greater challenges in meeting a
NOX limit and applying SNCR.
    Industry 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. Industry 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.
    Industry commenter (64) also believes that EPA has not given
adequate consideration to ammonia slip from the use of SCNR. EPA seems
to acknowledge that it does not have data on how ammonia slip will
contribute to condensable PM emissions, and what if anything could be
done to mitigate that contribution. EPA has not conducted a sufficient
technical analysis to support new NOX emission limits that
would effectively require use of SNCR without addressing the ammonia
slip issues. Ammonia slip may be a particular problem when SNCR is
applied to particular designs, such as pyro systems that have been
modified or that are particularly large. The inability of these systems
to promote the reaction of ammonia with NOX also reduces
potential control efficiency of SNCR on these systems.
    Industry 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 industry commenter (64) recommends that for preheater/
precalciner kilns (whether constructed at Greenfield or brownfield
sites), a NOX emission floor of 1.95 lb/ton of clinker be
established as the NSPS limit. This limit would then be modified on a
case-by-case basis to account for site-specific factors such as the
presence of a bypass stack/duct or difficult to burn limestone or
fuels, likely resulting in an emission limit in excess of the
recommended floor.
    Response: The previous response addresses the industry commenters'
concerns regarding the appropriateness of the NOX emissions
limit. Based on the data received prior to proposal as well as data
submitted after proposal, we feel confident that a well designed
preheater/precalciner kiln using low NOX process technology
such as LNB and SCC will be able to achieve a NOX emission
level of 3 lb/ton of clinker or less and using a well designed and
operated SNCR system will achieve NOX removal efficiencies
of at least 50 percent without excess ammonia slip. But should a case
occur where NOX emissions prior to application of SNCR are
above 3.0 lb/ton clinker, we have set the limit sufficiently high that
a facility could increase the NMR for SNCR to achieve removal
efficiencies above 50 percent without causing excessive ammonia slip.
Referring to Figure 2 above on NMR verses removal efficiency, we note
that a NMR of 1 results in a removal efficiency above 75 percent, where
a NRR of 1 equates to a point where excessive ammonia slip can occur.
    The industry commenters point to numerous factors that can
influence NOX emissions, fuel volatility and type of fuel
nitrogen being two factors mentioned. However, we note that facilities
have a choice of fuels. If their current fuel creates a high
NOX situation, then they may need to modify their fuel
choice. They again raise the issue of burnability but in the context of
certain product types. Again we note that there are numerous facilities
that achieve NOX levels well below 3.0 lb/ton clinker
located at various locations, some of which have ``hard to burn'' raw
materials. The industry commenters provided no data to substantiate
that the burnability issues associated with product types are any more
severe that burnability issues associated with different raw materials.
Given these different locations, we would surmise that they also use
different coals and possible other fuels. Given the breadth of the
data, we find it unlikely that we have not sufficiently covered all the
variables that affect NOX emissions. And also given the
operating margin we have applied for SNCR (50 percent reduction on
average versus a potential reduction of 75 percent), we continue to
believe that the 1.5 lb/ton clinker emission limit is achievable under
any reasonable foreseeable conditions without resulting in excessive
ammonia slip (and the attendant potential to produce PM2.5).
Industry commenters note that a larger kiln may have problems with
ammonia distribution and an attendant reduction in SNCR efficiency.
However, they provided no data to substantiate that claim, and we note
that some of the kilns achieving levels well below 3.0 lb/ton clinker
are above 1 million tpy in size. For larger kilns, it should be
possible to use a split exhaust dust if necessary to achieve the
required ammonia distribution.
    Some industry comments expressed concern that sources will have to
actually be able to reduce emissions to below the NOX limit
in order to not exceed the limit. In proposing the NOX
limits, EPA took this into consideration when it set the NOX
limit as a 30-day average as opposed for example to a 24-hr limit.
Doing so accommodates occasional daily excursions and accounts for
operational variability.
    EPA agrees with the industry commenters that kilns equipped with
alkali bypasses cannot be expected to meet the NOX limit for
the portion of the exhaust that goes to bypass. Bypass gases are
quickly cooled and do not remain at a temperature long enough to be
treated using an SNCR systems. EPA has revised the rule to clarify that
for kilns with alkali bypasses, only the main kiln exhaust gases are
subject to the NOX limit. Because all kilns do not

require an alkali bypass and the bypass gas stream is a small fraction
of the total kiln exhaust gas flow, the emission of NOX from
the bypass will be minimal.
    Comment: Several State and environmental advocacy group commenters
(60, 68, 70, 71, 72) stated that the proposed limits for SO2
were not sufficiently stringent. State commenter (60) recommends
deleting the 90 percent reduction option, revising the limit for
SO2 to 0.5 lb/ton clinker on a 24-hr rolling average if the
kiln is a PH or PH/PC kiln and adding a limit of 1.0 lb/ton clinker on
a 24-hr rolling average if the kiln is a long wet or long dry kiln.
State commenter (72) concurs on reducing the limit to 0.5 lb/ton for
PH/PC kilns. State 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. Industry commenter (60) cites kiln
performance at brownfield sites that have involved new kilns and
reconstructed or modified of existing kilns.
    Cement plants in Florida emit on the order of 0.10 lb
SO2/ton clinker. Although these kilns use low-sulfur feed
materials, all use coal and rely on the fuel SO2 control
that is inherent in the PH and PH/C designs. The steps include reaction
with alkali and incorporation into the clinker in the burning zone, dry
scrubbing with finely divided lime in the calcination zone and moist
limestone scrubbing in the raw mill. State commenters (60) and (72)
cite the performance of the kilns used by EPA to establish the proposed
limit. The key kiln (kiln 5 at TXI Midlothian, TX) upon which EPA based
the proposed SO2 standard of 1.33 lb/ton has actually
operated at 0.37 to 0.57 lb/ton.
    State commenters (60) and (72) state that raw materials in the
Midlothian area are known to be high-sulfur and the TXI kiln has a wet
scrubber to reduce (non-fuel) SO2 emissions. The limit for
kiln 5 is now approximately 0.95 lb/ton following a production increase
authorized by the Texas Commission on Environmental Quality (TCEQ). TXI
Midlothian Kiln 5 and two other PH/C kilns (Kilns 1 and 2) operated by
Holcim in the same city are controlled by wet scrubbers. All three have
wet scrubbers yet there is a vast difference in performance between the
TXI Kiln 5 and the Holcim Kilns 1 and 2. The commenter presented data
on the SO2 performance of the 3 scrubber controlled kilns.
According to the commenter, the TXI Kiln 5 can consistently achieve
SO2 emissions less than 0.5 lb/ton if required by a permit
limit. The higher SO2 values for the Holcim kilns (>4 lb/
ton) represent the first year of joint operation. Thereafter, Holcim
Kilns 1 and 2 were operated at levels between 2 and 3 lb/ton. The
commenter states that they can choose to run one to four pumps
providing reductions in SO2 emissions ranging from 51
percent with a single pump in operation to 91 percent with four pumps
in operation.
    State commenters (60) and (72) state that the Ash Grove Chanute PH/
C kiln in Kansas achieves less than 0.30 lb SO2/ton despite
high sulfur in the raw materials without even using a wet scrubber.
State commenter (60) states that this performance is attained using
important innovations (The F.L. Smidth DeSOx system and Envirocare
Micromist Lime system) not yet assessed by EPA. Attachments provided as
part of the comment describe these technologies. State 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 state
commenter (60), using the described technology, actual emissions from
the Ash Grove Chanute kiln are less than 0.25 lb SO2/ton.
    According to State commenter (60), the Holcim Siggenthal PH kiln in
Switzerland achieves approximately 0.05 lb SO2/ton using the
POLVITEC coke filter installed in the 1990's. The POLVITEC system is
used with various concurrent operational practices to control NH3 (from
an SNCR system), SO2, PM and metals. Among several
functions, the coke filter captures the non-fuel SO2
generated in the PH. The coke is subsequently crushed and then burned
with fuel in the main kiln burner. The SO2 from the PH then
behaves like fuel SO2 and is incorporated into the clinker.
Further details are available in an attachment submitted with the
comment. The State commenter also states that SO2 emissions
would be significantly less than 0.10 lb/ton of clinker. According to
the State 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.
    State commenters (60) and (72) state that the Holcim Untervaz plant
in Switzerland achieves between 0.04 and 0.21 lb SO2/ton
using a wet scrubber despite, according to State 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 State commenter indicate significant reductions in
SO2 emissions since 2002 largely due to the replacement of
the older dry scrubber with a more efficient and economic wet scrubber.
    According to State commenter (60), the areas where medium sulfur
raw materials are present can implement programs similar to the Ash
Grove installation without installing large wet scrubbers, dry
scrubbers or coke filters. Finally selective mining of the available
raw materials with respect to sulfur content is an important
SO2 control strategy for any new project. In summary, State
commenter (60) recommends an NSPS SO2 limit of 0.50 lb/ton
of clinker on a 24-hour basis for PH and PH/C kilns. State 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.
State commenter (60) agrees with EPA's assumption that new projects
triggering the NSPS will result in a PH/C kiln. According to the State
commenter, projects that might trigger a PSD review at a long wet or
long dry kiln will probably incorporate emissions control measures to
avoid PSD and a BACT determination. The measures to avoid PSD will also
likely avoid the short-term emissions increases that would otherwise
trigger the NSPS. With respect to the reconstruction provisions, the
commenter states that it is not likely that a company will actually
invest 50 percent of the (undepreciated) value of an existing long kiln
without taking the opportunity to make it much more energy efficient
through conversion to a PH/C kiln. Nevertheless, the State 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 State
commenter, scrubbers are available for long kilns just as they are
available for PH and PH/C kilns. Other suggested strategies cited by
the commenter include (1) Near mid-kiln pressurized air injection; and
(2) Chains near the entrance of the kiln that can improve contact
between the incoming wet limestone and the SO2-laden exhaust
gases containing both raw material and fuel sulfur.
    State commenter (60) states that good SO2 control will
make it possible to employ more aggressive NOX control and
that the control of NOX and SO2 will also
minimize the formation of ozone and fine PM in the environment.
    State commenters (68, 70, 71) stated 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, these State commenters find that most cement kilns
already achieve lower SO2 emissions than the 1.33 lb/ton of
clinker proposed.
    State 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: Most kilns have low SO2 emissions because of
the widespread availability of raw materials with low to moderate
sulfur levels and the inherent scrubbing effects of modern PH/PC kilns
with in-line raw mills. In fact, these two reasons have been cited as
BACT in several NSR reviews. Sulfur in the fuel is typically not a
problem because the sulfur content is relatively low and the sulfur has
ample opportunity to react with clinker and dust both in the kiln and
raw mill before the exhaust gases are discharged to the atmosphere. The
sulfur that usually results in higher SO2 emissions is due
to pyritic sulfur contained in the raw materials, especially the
limestone. Where kilns have high levels of pyritic sulfur in their raw
feed, wet scrubbers may be necessary to meet the limit for
SO2.
    We note that in our analysis of the NESHAP, all new kilns will have
to apply wet scrubbers to meet the HCl emissions limit. If this indeed
occurs then costs of wet scrubbing to meet the SO2 will be
negligible. Even in the absence of the NESHAP requirements, the
application of a wet scrubber to a kiln that has high uncontrolled
SO2 emissions is a cost effective approach to reducing
SO2 emissions. At higher uncontrolled emission levels, wet
scrubbers achieve emission reductions of 90 to 95 percent. However, at
lower uncontrolled SO2 levels, removal efficiency declines
resulting in an increase in cost-effectiveness. But at this point other
cost-effective control techniques, such as lime injection, are
available. Based on these facts, we have lowered the SO2
emission limit in this final rule to 0.4 lb/ton clinker or a 90 percent
reduction in SO2 emissions, which addresses the comments
that the proposed SO2 limit was too high.
    Comment: Several industry commenters (64, 74, 75) expressed
concerns that the proposed limits for SO2 are too stringent.
One industry commenter (64) recommends that EPA not include
SO2 limitations because EPA recognizes that there are only
``a few locations'' where the raw materials contain high levels of
sulfur, and in those few situations State regulations already impose
SO2 emission limitations that require the type of technology
EPA proposes as the basis for the proposed SO2 limitations.
The industry commenter states that EPA assumes that one out of five new
kilns will be sited where the raw materials are high in sulfur,
requiring an SO2 scrubber or a lime injection system when in
fact at existing plants there have only been a handful of situations
where high-sulfur materials have been determined to justify wet
scrubbers. According to the industry 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 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 industry commenter states that the preamble
information that the fact 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 industry 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 industry
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.
    Industry commenter (64) states that allowing State and site-
specific requirements to address SO2 at plants with high-
sulfur raw materials would address weaknesses in EPA's proposed
SO2 standards. For example, although EPA assumes that the
proposed SO2 standards will require add-on controls only at
facilities with high-sulfur raw materials, EPA has proposed a limit of
1.33 lb of SO2 per ton of clinker, whereas the average
emission rate from just 18 data points from tests at facilities with
moderate levels of sulfur in raw materials was 1.3 lb/ton. EPA's
assumption that facilities with low and moderate levels of sulfur in
raw materials would not have to install controls to meet the proposed
SO2 standards is not justified by those data. Requiring
facilities with moderate uncontrolled SO2 emission levels to
use add-on controls for SO2 would result in excessively high
costs per ton of SO2 removed, as EPA has recognized. Also,
the energy penalty associated with wet scrubbers could more
appropriately be evaluated on a case-by-case basis, where it can be
weighed against factors such as the level of uncontrolled
SO2 emissions at the particular plant and the need for
further SO2 reductions at that location for attainment and
maintenance of SO2 ambient air quality standards.
    Industry commenter (64) states that because there is so little
experience with add-on SO2 controls, EPA has relatively
little data about the performance of those controls, and is proposing
NSPS for SO2 based solely on a recent BACT determination.
The few kilns that will be subject to the proposed subpart F NSPS can
be addressed through requirements for SO2 control derived
through the RACT process or through NSR.
    Industry 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 industry
commenter infers from the monitoring provisions that EPA intends for a
source to compare the SO2 concentration at the inlet to the
scrubber to the SO2 concentration at the outlet from the
scrubber, but this does not reflect the substantial reduction in
SO2 emissions that occurs from contact with alkaline
materials in the process. The industry 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 industry 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.
    Industry commenter (64) states that the proposed regulations lack
any discussion of whether the SO2 limitations apply during
periods of startup, shutdown, and malfunction. Since substantial
reduction of SO2 occurs naturally in the cement-making
process because of the alkaline nature of the raw feed, industry
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 industry commenter states that several
recent BACT determinations involving

scrubbers include special provisions for startup, shutdown, or
malfunction.
    Industry commenter (64) states that the proposed limits for
SO2 appear inconsistent with their stated technology basis,
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 industry commenter,
NSPS should be based on demonstrated technology that can be applied to
the sector as a whole, rather than based on raw materials that are
available only in a limited area of the country. These BACT
determinations also undermine EPA's stated assumption that 1.3 lb/ton
represents a ``moderate uncontrolled SO2 emission rate'' and
13 lb/ton would be ``a high uncontrolled SO2 emission
level,'' since almost all BACT determinations for plants other than
those in Florida imposed SO2 emission limits based on no
add-on controls higher than 1.3 lb/ton, and a number were higher than
13 lb/ton.
    Industry commenter (64) states that if EPA insists on promulgating
NSPS for SO2, it is essential that the standards retain the
proposed option of meeting either a pounds per ton of clinker or a
percentage reduction limit; but both limits should be higher than
proposed. According to the commenter, the three wet scrubbers operated
by Holcim were not designed to achieve 90 percent reduction, and the
one BACT determination that contains an estimated percentage reduction
in the RBLC uses 85 percent reduction. Importantly, cement plants in
arid venues may not have the option to use a wet scrubber because of
water restrictions. Especially if EPA persists in applying the revised
NSPS to existing, modified or reconstructed facilities, wet scrubbers
cannot be considered demonstrated available technology for all
facilities in the source category. EPA does not, and industry commenter
(64) believes EPA cannot, support a 90 percent reduction requirement
using dry scrubbers or lime injection. According to the industry
commenter, to qualify as a limit based on demonstrated technology, the
limit should be achievable at all types of plants, raw materials, and
locations, and should be based on actual performance data rather than
what is ``reportedly'' achievable or anticipated.
    Industry 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 industry commenter states that
EPA describes one kiln where uncontrolled SO2 emissions are
``about 13 lb/ton of clinker.'' Achieving 90 percent reduction of that
uncontrolled emission rate would just meet the proposed mass limit,
with no margin of compliance. And in any event, at least four of the
BACT determinations for cement kilns in the past 10 years reported in
the RBLC reflect uncontrolled SO2 emission rates over 20.0
lb/ton. The proposed limit of 1.33 lb/ton thus does not reflect a limit
that has been demonstrated as achievable applying wet scrubber
technology to the range of sulfur contents present in cement plant raw
materials.
    One industry commenter (74) states that the proposed SO2
limit may be achievable in most cases but different plants will require
different solutions to achieve that limit. Due to the large variations
in the elemental and pyritic sulfur from plant to plant, industry
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 industry commenter (75) states that: (1) Given the range of
pyritic sulfur in our raw material, we would need to have a wet
scrubber to meet this limit; (2) Lime injection is an effective control
with less secondary impacts on water supply and energy use; and (3) A
limit of 4 lb/ton of clinker should be adopted. This would allow
greater use of lime injection, providing significant SO2
reductions while avoiding secondary adverse environmental impacts and
energy use of wet scrubbing. The industry 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. Industry 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: EPA disagrees with the industry commenter that the Agency
is under no obligation to set standards for SO2 as evidenced
by the lack of any SO2 limits previously or the infrequent
need for scrubbers (5 out of 20 new kilns expected to need scrubbers).
The absence of SO2 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. Since then, wet
scrubbers have been installed on no less than five kilns and operate
continuously. Other scrubbers, dry and wet, are installed on other
kilns and operate as needed. In reference to the industry commenters'
observations regarding permitted kilns in the RBLC database, EPA notes
that three kilns for which scrubbers are reported as an add-on control
device have permit limits far in excess of the NSPS SO2
limits indicating a clear need for national standards for
SO2 emissions from cement kilns. Furthermore, controlling
SO2 emissions will control emissions of condensable fine
particulate matter, leading to very significant environmental benefits.
See Table 13 in Section VI. Control is consequently in keeping with the
ultimate goals of the Act in general and section 111 in particular:
protecting and enhancing the Nation's air quality. See Asarco v. EPA,
578 F. 2d at 327.
    In response to the industry commenters' argument that kilns
utilizing raw materials with moderate sulfur levels may have to install
controls to comply with the SO2 limit, EPA agrees that in a
few instances those kilns may need to reduce their SO2
emissions. However, these kilns only need moderate reductions in
SO2 and have options other than adding wet scrubbers
(assuming no wet scrubbers are needed to meet the NESHAP HCl standard).
In addition to the inherent scrubbing that occurs with the raw mill,
cement plants can and do also practice careful selection of their raw
materials to avoid high sulfur materials. There are cement plants that
already limit the sulfur in their raw materials through their mining
practices and through screening the raw materials they purchase. Owners
and operators also reduce SO2 emissions by not burning
sulfur-containing coal and by burning natural gas during kiln
preheating, shutdown and during other maintenance periods when the kiln
and/or raw mill are down. In those instances when some additional
reduction is necessary, a less expensive alternative to wet scrubbing
is lime injection. Lime injection can achieve up to 70 percent
reduction and may only be necessary during periods of higher
SO2 emissions, for example when the raw mill is off.

    In response to the industry commenter's questions of how the 90
percent reduction is to be determined, they are correct that the
reduction is to be measured across the scrubber (in other words,
measurements must be made to measure the SO2 entering the
scrubber and the SO2 exiting the scrubber). Like the
SO2 standard, the rule states explicitly that the 90 percent
reduction is to be based on a 30-day average. In the case of lime
injection, EPA believes this add-on control will only be used in
situations requiring a modest reduction in SO2 emissions and
these kilns will be able to meet the SO2 emissions limit.
    EPA disagrees with the industry commenter's suggestion that EPA
provide some allowance for periods of startup, shutdown or malfunction
as SO2 emissions are affected by whether the raw mill is
operating or not. The industry commenter requested that EPA allow that
during these periods, scrubbers or lime injection systems need not
operate or at least need not operate at maximum efficiency. The
industry commenter provided no data to indicate that, given the long
averaging periods, a facility's raw mill up time versus down time is
significantly affected by periods of startup and shutdown. In fact, the
reason for the 30 day averaging period was specifically to allow a long
enough averaging period that the higher emissions that occur for
SO2 when the raw mill is down could be averages with long
periods when the raw mill is operating.
    EPA disagrees with the industry commenter's statement that the
proposed limits for SO2 appear inconsistent with their
stated technology bases, when compared to actual experience and to BACT
determinations. The standard was based on the performance of a
scrubber-equipped kiln that processed high sulfur limestone. The
alternative to the SO2 emission limit is to demonstrate a 90
percent removal efficiency across the scrubber. EPA could not ignore
the performance of this control technology, i.e., wet scrubbers, which
are currently used full time at 5 cement plants. In reviewing the RBLC
database, it is obvious that, in some cases, permit limits are not as
stringent as they could be. One entry in the RBLC database even stated
that the permit limit did not account for the reduction that would be
achieved by the scrubber installed to control SO2.
    We note that industry commenters have stated that some new
facilities may be located in areas where there is not sufficient water
to operate a wet scrubber. However, we are not mandating the use of wet
scrubber technology in these regulations, and we believe that
sufficient alternative controls exist for SO2 controls that
this issue would not preclude a facility from meeting these emissions
limits. As previously noted, these alternative technologies include dry
lime injection, injection of sodium compounds, selective mining,
injection of a finely divided lime slurry, use of lower sulfur fuels,
and careful screening of purchased raw materials. Regarding the
industry commenter's statements that the emission limit and alternative
percent reduction should be less stringent, EPA notes that the kiln
upon which the emission limit was based actually operates at levels
under 0.6 lb/ton clinker based on information supplied by another
commenter (60). The same industry commenter states that the limit for
the kiln was reduced in 2007 from 1.33 to 0.95 lb/ton following a
production increase authorized by the Texas Commission on Environmental
Quality. To support its statement that a 90 percent removal efficiency
is too high, the industry commenter noted that three Holnam (now
Holcim) plants use scrubbers that are designed to operate at less than
90 percent efficiency. Our data for the scrubbers at the Texas plant
shows that the removal efficiency depends on the number of pumps in
operation, with 91 percent efficiency when all four pumps are
operating. The scrubbers at the Holnam facility in Michigan have not
operated continuously due to various issues encountered. We also note
that SO2 scrubbers in the utility industry have consistently
achieved 90 percent SO2 since the 1970s. We see no technical
reason that the same removal levels are not achievable in the cement
industry. Therefore, where add-on controls are necessary to comply,
scrubbers designed to achieve at least a 90 percent efficiency or
greater are expected to be able to meet the 90 percent efficiency
alternative; cement plants may be able to meet the emission limit by
utilizing scrubbers with less than 90 percent efficiency or with lime
injection if the uncontrolled SO2 levels are at moderate
levels (assuming that wet scrubbers are not needed to comply with other
requirements, such as the HCl standard in the NESHAP).
    EPA does not agree with the industry commenter that the limit of
1.33 lb/ton based on uncontrolled SO2 emissions of 13 lb/ton
of clinker and a 90 percent reduction leaves no margin for compliance.
First, there are scrubbers with efficiencies higher than 90 percent
removal efficiency, which, even if they can't meet the 1.33 (or the
0.4) lb/ton clinker emission limit, will be able to consistently meet
90 percent removal. Secondly, based on an industry commenter, the
SO2 emissions from a PH/PC kiln are not likely to be as high
as 13 lb/ton of clinker due to the scrubbing effects of the raw mill,
but more in the range of 4-5 lb/ton of clinker (75). This is supported
by data from a 2001 survey of cement plants showing that average
SO2 emissions from PH kilns was 1.39 lb/ton of clinker
(maximum of 6.54) and from PC kilns was 1.92 lb/ton of clinker (maximum
of 8.83). Based on these data, use of a wet scrubber should be able to
meet the proposed SO2 limit of 1.33 and the final limit of
0.4 lb/ton clinker. In some cases, a less expensive control such as
lime injection may be adequate. Regarding the industry commenters
reference to determinations reported in the RBLC that reflect
uncontrolled SO2 emission rates over 20.0 lb/ton, these
rates (if they are accurate) are associated with old wet kilns that do
not have inline raw mills. In the case of one the two Michigan kilns,
the quarries raw materials are known to have extremely high sulfur
contents that are not seen at other locations. However, even if this
location decided to build a new kiln, or to modify or reconstruct an
existing kiln, they would still have the option to meet the 90 percent
removal option.
    In response to the industry commenter that states it is not fair to
have a set SO2 limit for all plants and that each plant's
limit should be considered on a case-by-case basis, EPA points out that
the standards gives plants an alternative to the SO2 limit
recognizing, just as the industry commenter states, that some plants
may not be able to meet the SO2 limit due to the presence of
pyritic sulfur in its limestone. Where plants cannot meet the
SO2 limit, they have the option of complying with the
alternative limit of showing a 90 percent reduction in SO2
emissions.
    EPA disagrees with one industry commenter's suggestion of setting
the SO2 limit at 4 lb/ton clinker in order to allow greater
use of lime injection systems. Given that there are cost-effective
controls to achieve much lower levels, a limit of 4 lb/ton clinker
simply cannot be considered BDT. We also note that EPA does not specify
the type of control that must be used to meet the limit, or, for that
matter, that any specific control has to be used. Plant owners may use
any add-on control, such as lime injection if a control is necessary,
or process control, such as selective mining, or a combination of add-
on and process controls to meet the

limit. The industry commenter states that it mined its materials
locally for over 100 years and plans to continue to do so. However,
almost all cement plants in the country could make a similar statement,
and it has no relevance and does not change the facts that cost-
effective SO2 controls are available to achieve
SO2 emission levels of 0.4 lb/ton clinker.
    Comment: One industry 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 industry 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 industry 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. EPA does
not currently have sufficient information on emissions of condensable
PM from cement kilns to set emission limits and the limited information
we do have is highly uncertain. We also believe that these emissions
will be controlled via controls on HCl in the NESHAP and SO2
in the NSPS. EPA has recently promulgated a new test method for
condensable PM (Method 202) which will allow for more reliable
assessments of condensable PM. We anticipate that better data will be
available at the time of the next review of the NSPS.
    Comment: Several industry commenters (64, 73, 74, 83) expressed
concerns over the proposed NSPS for PM of 0.086 lb/ton of clinker.
Industry 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. Industry commenters believe 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. Industry 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. Industry
commenter (73) and (74) also believe that when clinker cooler and kiln
gases are combined, the standard for these systems should be additive.
    The industry 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 industry commenters, in most
cases, emission rates achieved immediately after installation of
pollution control equipment will not be representative of the
performance over the life of the source, as the bags and the baghouse
itself age and experience normal wear, even with proper operation and
maintenance. Industry 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. Industry
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: As noted in the previous comments on the NESHAP PM limit,
we have reevaluated the performance of PM controls for this source
category and have determined that the appropriate NESHAP new source
standard is 0.1 lb/ton clinker based on a 30 day rolling average.
Because all new sources will be required to meet this limit, we see no
reason to set a different limit for the NSPS. We note the industry
commenter's performance concerns. However, in setting the NESHAP limit
we reviewed test data from a number of facilities. Some facilities had
average emissions as low as 0.007 lb/ton clinker based on short term
testing, and the average of the best performing five facilities was
0.019 lb/ton (based on multiple short term testing). Based on this
information, we believe that if the PM control is properly designed and
maintained, PM levels well below the level we proposed, or the levels
suggested by the commenter are possible. In addition, the data
discussed were short term tests. Compliance will be based on a 30-day
rolling average, which allows facilities to average out potential short
term transients.

VI. Summary of Cost, Environmental, Energy, and Economic Impacts

A. What are the impacts of the final amendments to subpart LLL and
subpart F?

    We are presenting a combined discussion of the estimates of the
impacts for these final amendments to 40 CFR part 60, subpart F and 40
CFR part 63, subpart F. The cost, environmental, and economic impacts
presented in this section are expressed as incremental differences
between the impacts of a Portland cement plant complying with the
amendments to 40 CFR 63 subpart LLL 40 CFR part 60 subpart F and the
baseline, i.e., the standards before these amendments. The impacts are
presented for the year 2013, which will be the year that all existing
kilns will have to be in compliance, and also the year that will
represent approximately 5 years of new kiln construction subject to the
amended NSPS emissions limits. The analyses and the documents
referenced below can be found in Docket ID Nos. EPA-HQ-OAR-2007-0877
and EPA-HQ-OAR-2002-0051.
1. What are the affected sources?
    We expect that by 2013, the year when all existing sources will be
required to come into compliance, there will be 100 Portland cement
manufacturing facilities located in the U.S. and Puerto Rico that we
expect to be affected by these final amendments. Of these facilities,
approximately 5 are complete new greenfield facilities. These
facilities will operate 158 cement kilns and associated clinker
coolers. We have no estimate of the number of raw material dryers that
are separate from the kilns.
    Based on capacity expansion data provided by the Portland Cement
Association, we anticipate that by 2013 there will be 16 kilns and
their associated clinker coolers subject to NESHAP new source emission
limits for mercury, HCl, and THC, and seven kilns and clinker coolers
subject to the amended NSPS for NOX and SO2. Some
of these new kilns will be built at existing facilities and some at new

greenfield facilities. The location of the kiln (greenfield or
currently existing facility) has no bearing on our estimated cost and
environmental impacts (since there are no longer separate standards for
so-called greenfield new sources).
    As previously noted there are two kilns with unusually high mercury
emissions that we believe cannot meet the mercury emissions limit
without using more than one control technique. In developing the cost
impacts, we assume that they would require multiple mercury controls.
The only mercury controls available for which we have detailed cost
data are ACI and wet scrubbers, so we costed both controls to develop
what we consider to be a reasonable cost estimate for these facilities.
This does not imply that we believe these facilities will specifically
use a combination of a wet scrubber and ACI to meet the mercury limit,
but we do believe the combination of these control results in a
reasonable estimate of cost.
2. How are the impacts for this proposal evaluated?
    For these final Portland Cement NESHAP amendments, EPA utilized
three models to evaluate the impacts of the regulation on the industry
and the economy. Typically in a regulatory analysis, EPA determines the
regulatory options suitable to meet statutory obligations under the
CAA. Based on the stringency of those options, EPA then determines the
control technologies and monitoring requirements that sources might
rationally select to comply with the regulation. This analysis is
documented in an Engineering Analysis. The selected control
technologies and monitoring requirements are then evaluated in a cost
model to determine the total annualized control costs. The annualized
control costs serve as inputs to an Economic Impact Analysis model that
evaluates the impacts of those costs on the industry and society as a
whole.
    The Economic Impact Analysis model uses a single-period static
partial-equilibrium model to compare a pre-policy cement market
baseline with expected post-policy outcomes in cement markets. This
model was used in previous EPA analyses of the Portland cement industry
(EPA, 1998; EPA, 1999b). The benchmark time horizon for the analysis is
assumed to be short and producers have some constraints on their
flexibility to adjust factors of production. This time horizon allows
us to capture important transitory impacts of the program on existing
producers. The model uses traditional engineering costs analysis as
``exogenous'' inputs (i.e., determined outside of the economic model)
and computes the associated economic impacts of the final regulation.
    For the Portland Cement NESHAP, EPA also utilized the Industrial
Sector Integrated Solutions (ISIS) model which conducts both the
engineering cost analysis and the economic analysis in a single
modeling system. The ISIS model is a dynamic and integrated model that
simulates potential decisions made in the cement industry to meet an
environmental policy under a regulatory scenario. ISIS simultaneously
estimates (1) optimal industry operation to meet the demand and
emission reduction requirements, (2) the suite of control technologies
needed to meet the emission limit, (3) the engineering cost of
controls, and (4) economic impacts of demand response of the policy, in
an iterative loop until the system achieves the optimal solution. The
peer review of the ISIS model can be found in the docket.\45\ This