through the span value, but the scale is not limited to that range.

Comment: One commenter (2855) said that the PS-12A requirements at 6.2
Reference Gas Delivery System are ambiguous, unlikely to be achieved
exactly in practice, and without means of verification. The commenter
recommends changing the section from The reference gas delivery system
must be designed so that the flowrate of reference gases introduced to
the CEMS is the same at all three challenge levels specified in Section
7.1, and, at all times exceeds the flow requirements of the CEMS. To The
reference gas delivery system should be designed so that the referenced
gas flow rate is approximately the same (i.e., ± 20%) at each challenge
level.

Response: We have revised the language of section 6.2 of PS-12A to
specify that the reference gas delivery system must be designed so that
the flow rate exceeds the sampling system flow rate of the CEMS and that
the gas is delivered to the CEMS is at atmospheric pressure.

Comment: One commenter (2855) said that PS-12A Section 7.1 requires the
use of NIST certified or NIST Traceable standards for both elemental
mercury and oxidized mercury, which are not currently available, and may
not be available in the future at the specified levels, depending on
EPA’s resolution of the span value.

Response: As noted above, 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 µg/m3 and mercury gas
generator vendors may now submit elemental mercury gas generators for
certification to serve as ‘Vendor Primes’. Therefore, as previously
stated, 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.

Comment: One commenter (2855) said that PS-12A Section 8.1.1 includes a
vague requirement to use a sampling location that has been shown to be
free of stratification for mercury or alternatively, sulfur dioxide
(SO2) and nitrogen oxides (NOx) through concentration measurement
traverses for those gases. This requirement should be changed to a
suggestion or guidance.

Response: We have revised language in Section 8.1.1 to specify that the
sampling location must be representative of the stack gas concentration
of mercury and, as the commenter suggested, have modified the
requirement to use a location shown to be free of stratification to be a
recommendation.

Comment: One commenter (2855) said that the PS-12A criteria for the
linearity test procedures are more restrictive than the Part 75,
Appendix A criteria, are inconsistent with the uncertainty of
calibration materials defined by Interim EPA Traceability Protocols, and
should be relaxed.

Response: By specifying the linearity test procedure measurement error
criterion as a function of span, this criterion is generally less
restrictive at the lower gas concentrations than were the prior Part 75,
Appendix A criteria. We have, however, reconsidered the linearity test
procedure specifications and, given the current quality of the available
oxidized mercury gas standards, we have decided to increase the allowed
measurement error for the oxidized mercury standards to + 10 percent to
be consistent with the target criteria in the EPA Interim Traceability
Protocol for Qualification and Certification of Oxidized Mercury Gas
Generators.

Comment: One commenter (2855) said that the PS-12A criteria for the
calibration drift (CD) test procedure: (a) omit the absolute CD
specification included in the Part 75, Appendix A criteria, (b) are
inconsistent with the uncertainty of calibration materials defined by
EPA draft interim traceability protocols, and (c) should be relaxed.

Response: With the exception of the alternative specification for a span
value of 10 µg/m3 or less, the PS-12A criterion for calibration drift
is essentially identical to the Part 75, Appendix A criteria for
calibration error.

Comment: One commenter (2855) said that the proposed revisions to
Subpart LLL and PS-12A fail to specify the conditions under which the
relative accuracy test is performed which will lead to inconsistent
interpretations and implementation requirements. Subpart LLL should
specify that the CEMS relative accuracy test be performed at the most
prevalent operating condition (i.e., mill on for plants with in-line raw
mills).

Response: We have revised paragraph 63.1350(n) of Subpart LLL to specify
operating conditions for relative accuracy testing.

Comment: One commenter (2855) said that sections 9.0 (Quality Control)
and 10.0 (Calibration and Standardization) are both reserved. Quality
Control procedures and Calibration and Standardization procedures must
be considered to determine the overall validity and reasonableness of
the performance specification. Without these integral sections, an
evaluation of the acceptability of this specification cannot be made.
When completed, EPA should re-propose PS-12A for public comment.

Response: These section headings are a result of using a standardized
method format originally specified by EPA’s Environmental Monitoring
Management Council [see http://www.epa.gov/ttn/emc/guidlnd/gd-045.pdf].
The substance of these reserved sections are covered elsewhere in
PS-12A, Procedure 5, and the Interim Traceability Protocols for
Elemental and Oxidized Mercury Gas Generators.

Comment: One commenter (2855) said thatPS-12A as proposed would make the
relative accuracy specification stricter for certain CEMS than is
required by Part 75, Appendix A and B.

Response: After consideration of the potential variability between the
learning curves for CEMS operators that new users of Hg CEMS may
experience, we have revised the relative accuracy specification in
PS-12A from 10 percent to 20 percent. We believe, however, that the
implication of this change is minor and short-lived because most
facilities that install Hg CEMS will find that they readily achieve
relative accuracies far better than 20 percent.

Comment: One commenter (2915) provided the following specific comments
on PS-12A:

Section 3.5–Span value is an obsolete term. Current technology has a
linear measurement range that covers several orders of magnitude.

d be a fixed number in terms of measurement units (μg/m3). Like this
proposed rule revision, many mercury emission limits are not expressed
in terms of μg/m3. The proposed cement MACT is expressed in pounds of
mercury per million tons of clinker. EPA should revise Section 3.5 to
state that the span should be set in accordance with applicable
regulations for the use of the Mercury CEMS.

The commenter suggested a revised definition of span: Span Value means
the intended upper limit of the mercury concentration measurement range.
The span value is specified in the applicable subpart.

Response: We have modified the definition of span in PS-12A to provide
additional flexibility in setting a span value including allowing for
rounding up to the nearest multiple of ten and clarifying that the
applicable subpart may contain more specific provisions regarding the
span value for specific source category. In this case, we have taken
another commenter’s suggestion to define span value for this source
category in paragraph 63.1350(n) of the subpart based on the intended
upper limit of the mercury concentration during “mill on” operation
and approximately equivalent to two times the emission standard.

Comment: One commenter (2915) stated that there are a limited number of
NIST traceable calibration levels available. Since the available
calibration values are all tied to specific span and linearity test
values, defining the span in terms of the emission standard will likely
result in spans that are inconsistent with the NIST traceable
concentrations.

Response: As noted above, 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 µg/m3 and mercury gas
generator vendors may now submit elemental mercury gas generators for
certification to serve as ‘Vendor Primes’. Therefore, as previously
stated, this capability means that 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
values both below and well above either standard. Also, as described in
previous responses, we have revised the definition of span to provide
additional flexibility in setting the span value consistent with the
available NIST traceable concentrations.

Comment: One commenter (2915) suggested that EPA review the Interim
Traceability Protocols for elemental and oxidized mercury generators so
that there will be regulatory compatibility.

Response: At the current time, we do not anticipate any issues with the
regulatory compatibility of the Interim Traceability Protocols used to
certify the NIST traceability of gases produced by mercury gas
generators; however, we do plan to review and update the protocols in
the future including clarifying that the protocols are not limited to
only providing procedures to qualify and quantify the performance of
mercury gas standards generators below 40 µg/m3.

Comment: One commenter (2915) said that in Section 3.7, EPA proposes to
define calibration drift in terms of a test performed on the CEMS after
a period of operation during which no unscheduled maintenance, repair,
or adjustment took place. The clause during which no unscheduled
maintenance, repair or adjustment took place should be removed. In the
commenter’s experience, unlike SO2 and NOx CEMS, mercury CEMS are
likely to require a significant amount of maintenance, repair and
adjustment. That same clause in PS-2 has been subject to considerable
debate and interpretation over the years and the commenter believes that
including it here will only result in further confusion. EPA also has
not explained why such a limitation is needed in this definition.

Response: We have removed the term ‘adjustment’ from this phrase in
Section 3.7 of PS-12A as we clearly consider adjustment following the
daily drift check to be an appropriate option (see also Sections 4.2 and
4.3 of Appendix F, Procedure 2 and of proposed Procedure 5). Maintenance
or repair of the Hg CEMS during a 7-day calibration drift test is not
acceptable as the point of the test is to confirm that the system can
operate for 7 days without unacceptable drift.

Comment: One commenter (2915) said that in Section 6.1.1–EPA proposes
several requirements related to [t]he Mercury CEMS data recorder output
range. These requirements are obsolete. All recording is now done by
computer and virtually all data transmission and recording is digital.
Digital data transmission and management allows one to eliminate the
span and range language problem because digital data have no range. Such
a change will allow sources to utilize the full several order of
magnitude measurement capabilities of modern analyzers–especially
mercury analyzers.

Response: Section 6.1.1 of PS-12A regarding the data recorder scale has
been revised to respond to the comments received. We have simplified the
specification to clarify that the scale must at a minimum include zero
through the span value. This revision will allow sources to utilize
multiple orders of magnitude, as needed.

Comment: One commenter (2915) disagreed with EPA’s proposed
requirement that the measured value not exceed 95 percent of the high
value. The measured value should be allowed to be as high as the
calibration value. This section should be eliminated or modified to
accommodate modern analyzers.

Response: We agree with the commenter and this specification has been
removed from Section 6.1.1 of PS-12A.

Comment: One commenter (2915) said that in Section 6.2–EPA proposes to
require that the reference gas delivery system be designed so that the
flow rate of the reference gas is the same at all levels. The commenter
is not aware of any reason for this requirement and EPA offers none.
Several of the commercial mercury calibrators (including the market
leader) are designed to vary the flow rate of the reference gas, and the
gas sampling probes are designed to vent any excess flow. This proposed
requirement would render those calibrators ineligible for use under the
proposed rule, without any stated justification. In the commenter’s
view, the only pertinent requirement in this section is that the flow of
the reference gas exceeds that required by the CEMS sample probe design.

Response: We have revised the language of Section 6.2 to specify only
that the reference gas delivery system must be designed so that the flow
rate exceeds the sampling system flow rate of the CEMS and that the gas
delivered to the CEMS is at atmospheric pressure.

Comment: One commenter (2915) said that in Section 7.1.1–EPA proposes
to require that the zero level reference gas concentration be
0-20 percent of the span value. The zero-level should be made 0-30
percent of span instead of 0-20 percent of span to capture the best
available NIST traceable concentrations. For example, the available NIST
concentrations for a 0-10 μg/m3 span are 1.1, 1.3 and 2.7 μg/m3. Of
these, the 2.7 μg/m3 concentration has been the standard low-level
calibration/linearity concentration because its uncertainty, per NIST
traceability calculations, is much lower than the other two
concentrations.

μg/m3 gas as the zero level reference gas, but use a zero gas in
addition, or (3) request that the gas generator vendor provide a
generator that can deliver a standard at 2.0 μg/m3 or below using
guidance in the protocols.

Comment: One commenter (2915) said that in Section 8.1.1, because
mercury CEMS generally use a single point measurement, EPA proposes to
require use of a location that has been shown to be free of
stratification for Mercury or alternatively, SO2 and NOx. The provision
then states that if the RA test is failed because of the location, EPA
may require that the CEMS be relocated. The commenter stated that this
provision is not reasonable and explains why.

Response: We have revised the language in Section 8.1.1 to specify that
the sampling location must be representative of the stack gas
concentration and have modified the requirement to use a location shown
to be free of stratification to be a recommendation rather than a
requirement.

cification of ±0.8 μg/m3 absolute difference.

Response: We have reconsidered the linearity test procedure
specifications and, given the current quality of the available oxidized
mercury gas standards, we have decided to increase the allowed
measurement error for the oxidized mercury standards to + 10 percent to
be consistent with the target criteria in the EPA Interim Traceability
Protocol for Qualification and Certification of Oxidized Mercury Gas
Generators.

Comment: One commenter (2915) said that in Section 8.4.3, EPA proposes
to require that CEMS meet a calibration drift specification of 5 percent
of the span value. The problem in this section is the same as discussed
in the Section 8.3 above. The specification cannot be supported by field
data and should be changed to ±10 percent of span with a ±1.0 μg/m3
absolute difference, whichever is less restrictive. This specification
will be similar to the Clean Air Markets Rule (CAMR) rule specification
in Part 75, which was difficult to achieve.

Response: We believe that the calibration drift specification of 5
percent of the span value is reasonable and that many installations of
mercury CEMS have been able to achieve the specification.

Comment: One commenter (2915) said that in Section 8.5.4, EPA proposes
to require a minimum sample time of 30 minutes for Method 30A. The
sample time specification is inconsistent with the method. The sampling
time for Method 30A will vary depending on the number of traverse
points. The minimum sampling time for Method 30B is 30 minutes and that
is not included in Section 8.5.4.

Response: The commenter is correct. Method 30A sampling time depends on
the number of traverse points. The reference should have been to Method
30B and we have revised the section accordingly.

Comment: One commenter (2915) said that in Section 8.5.5, EPA proposes
to require use of paired reference method values when using certain
methods to perform a relative accuracy test audits (RATA), including
Method 30A. Method 30A should be removed from the method list in this
section because it does not provide paired reference method values.

Response: The commenter is correct; Section 8.5.5 of PS-12A has been
revised to remove the reference to Method 30A.

e criteria applicable to paired reference method values used in RATAs.
Method 30B provides for an acceptance criteria ±0.2 μg/m3 absolute
difference between data pairs in addition to the 20 percent relative
difference criteria. The absolute difference criteria are missing from
this section. The commenter does not believe it is appropriate to modify
a reference method in a Performance Specification. EPA should add the
alternative specification or state that alternative specifications in
individual reference methods may also be used.

Response: We have revised Section <IP_ADDRESS> of PS-12A to be consistent
with Method 30B.

Comment: One commenter (2915) said that in Section 13 the relative
accuracy, linearity and calibration drift specifications are too
stringent and will result in a significant number of failures. The
commenter suggested that the linearity, calibration drift and relative
accuracy specifications in this section mirror those that were
promulgated in Part 75 for use under CAMR. A large quantity of field
data show that present day mercury CEMS technology cannot routinely
achieve the specifications proposed in Section 13.

Response: These issues have been addressed in earlier responses.

ceable is currently 47.5 μg/m3. This is far too low to be of use for
cement kilns where the most common span value will be 260 μg/m3. The
commenter stated that this problem can be solved in one of several ways:

If the bracketing system used for certification is demonstrated to be
linear, there would be no obstacle to having a candidate calibrator
certified at concentrations several times the concentration of the
reference calibrator. This applies to both the NIST and vendors’
bracketing systems. A change to the 25% difference limit would be
required.

NIST could certify a NIST prime calibrator at the target concentrations
for the cement rule. Note that using the same NIST prime unit for both
high and low concentrations might impact the certification accuracy of
the prime unit for low concentrations due to residual contamination.
Thus a second NIST prime calibrator for high concentrations would likely
be required.

Response: As noted earlier, 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 µg/m3 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.

Comment: One commenter (2894) stated that many of the span value
concepts in this proposed rule date back to the days of strip chart
recorders, analog instrumentation, and low resolution A/D converters. In
these legacy systems, exceeding an upper output limit meant that all
information was lost as the pen pegged or the A/D overloaded. In
contrast, all modern CEM systems provide digital interfaces that
transmit actual numbers. These are capable of high resolution over an
unlimited dynamic range. Commenter 2894 suggested that vendors should be
required to provide test data on the dynamic range of their CEM systems,
particularly at high concentrations. The regulation should allow
temporary exceedences of the span range provided that they fall within
this linear range. (Currently, data is considered invalid if
concentrations exceed the span range.) This is particularly essential if
the rule requires the monitoring of mercury during SSM periods. This
wide dynamic range should be allowed only on installations that do not
artificially limit their dynamic range by using older 4-20 mA or other
analog signal transfer methods.

Response: As explained in response to earlier comments, the data
recorder scale of Section 6.1.1 of PS-12A has been revised to respond to
the comments received. We have simplified the specification to clarify
that the scale must at a minimum include zero through the span value.
This revision will allow sources to utilize multiple orders of
magnitude, as needed. In addition, we have modified the definition of
span in Section 3.5 to provide additional flexibility in setting a span
value including allowing for rounding up to the nearest multiple of ten
and clarifying that the applicable subpart may contain more specific
provisions regarding the span value for specific source category. For
these amendments to Subpart LLL, we have taken another commenter’s
suggestion to define span value for this source category in paragraph
63.1350(n) of the subpart based on the intended upper limit of the
mercury concentration during “mill on” operation, but at least
approximately equivalent to two times the emission standard.

Comment: One commenter (2894) suggested that the new regulation should
ensure that as few new span ranges as possible are defined. According to
the commenter, in the U.S. power plant environment, mercury levels are
substantially lower than the emissions levels at cement kilns. The span
ranges that have been defined for power plants are: 2 μg/m3 (future
use), 5 (future use), 10, 20, 30 and 40 μg/m3. This is more than are
actually required, given the performance of all current CEM systems. (In
particular, the span range of 30 μg/m3 is superfluous.)

Each of these defined span ranges requires three distinct and separate
concentrations of calibration gas: low (20-30% of span), medium
(50-60%), and high (80-100% of span). This requirement would pose an
undue burden on both NIST and the vendors if too many new span ranges
are defined.

The commenter stated that any requirements for dual span ranges for a
CEM installation are archaic and should be deleted.

Response: With the revisions to the definition of span in PS-12A and
Subpart LLL monitoring requirements described in the previous response,
we have provided ample flexibility in span selection and have eliminated
the need for dual spans.

Comment: One commenter (2894) suggested upgrades to PS-12A:

6.1.1 Data Recorder Scale. This section deals with obsolete strip chart
recorder technology and should be either deleted or redrafted.

6.2 There are actually four gas levels being used in CAMR power plant
installations, not three: Zero, Low linearity, Mid Linearity and High
span. There is an inconsistency here. (i.e., Should the Low Linearity
gas actually be allowed to be in the range of 0-20% as specified in
PS-12A or 20-30% as is current practice?).

8.1.3 Mercury CEMS Sample Extraction Point. Are most cement kiln stacks
sufficiently large to allow sampling 1.0 meter from the stack wall?

8.3 Linearity Procedure. Currently, power plant CEMS are required to
inject at three non-zero concentrations, not two concentrations plus
zero. Will replacement power plant regulations still require three
non-zero concentrations or will this requirement be relaxed as per this
section?

Response: Section 6.1.1 of PS-12A regarding the data recorder scale has
been revised to respond to the comments received. We have simplified the
specification to clarify that the scale must at a minimum include zero
through the span value. This revision will allow sources to utilize
multiple orders of magnitude, as needed.

We note that the vacated Clean Air Mercury Rule specifications are no
longer relevant. The low (“zero-level”) reference gas must be in the
range of 0 to 20 percent of span.

Based on the information we have, yes, most cement kiln stacks are
sufficiently large to allow sampling 1.0 meter from the stack wall.

Replacement regulations for mercury emissions have not yet been
proposed, so we cannot provide a definitive response to the question on
Section 8.3. However, PS-12A allows linearity tests to be conducted at
three non-zero concentrations or at two non-zero concentrations plus
zero.

Comment: One commenter (2915) disagreed with the proposed mercury
performance specifications and with the provisions for setting Mercury
CEMS span values and the stringency of the proposed performance
specifications for both Mercury CEMS and sorbent trap monitoring systems
(STMS).

Commenter 2915 stated that EPA’s proposed Mercury performance
specifications include setting Mercury CEMS span values equal to twice
the applicable emission limit and to use that span value to determine
the levels at which the Mercury CEMS must be calibrated. 74 FR at 21172.
EPA’s approach to span does not reflect the measurement capabilities
of Mercury CEMS or the limited number of potential National Institute of
Standards and Technology (NIST) traceable calibration gases available to
calibrate Mercury CEMS of various spans.

Commenter 2915 stated that EPA also should define span in a manner that
is consistent with the regulations and permits that are likely to
require use of PS-12A and Procedure 5. Because most Mercury limits,
including the ones EPA proposes in this rule, are expressed in terms
other than µg/m3 (e.g., lb per million tons of clinker produced, pound
per trillion British thermal unit [lb/TBtu], or pound per megawatt hour
[lb/MWh]), the commenter disagrees with defining the required Mercury
CEMS span (which is expressed in µg/m3) in terms of the Mercury limit.
Instead, PS-12A should defer to the applicable regulation or permit to
define the span (in mg/m3) that is most appropriate for the intended
use.

Response: We have revised the definition of span in Section 3.5 of
PS-12A as well as Subpart LLL to provide additional flexibility. The
definition of span in PS-12A now clarifies that the span is the
measurement range specified in the applicable regulation or other
requirement. If the span is not specified in the applicable regulation
or other requirement, then it must be approximately two times the
emissions limit. The definition also allows for rounding up to the
nearest multiple of ten. In Subpart LLL, paragraph 63.1350(n), we have
defined the span value for this source category as based on the intended
upper limit of the mercury concentration during “mill on” operation,
but at least approximately equivalent to two times the emission standard
and again allowed for rounding up to the nearest multiple of 10.

Comment: According to commenter 2915 EPA should provide more data to
support its proposed tightening of the relative accuracy standard for
both Mercury CEMS and STMS relative to the vacated CAMR standards. As a
result of its work on the Interim Traceability Protocols and other
research efforts, EPA has had access to a considerable amount of
additional field data. The commenter stated that the proposed linearity,
calibration drift, and relative accuracy standards for Mercury CEMS are
too stringent and may be frequently failed.

Response: As noted in prior responses, after consideration of the
potential variability among the learning curves that new users of Hg
CEMS may experience, we have revised the relative accuracy specification
in PS-12A from 10 percent to 20 percent. We believe, however, that the
implication of this change is minor and short-lived because most
facilities that install Hg CEMS will find that they readily achieve
relative accuracies far better than 20 percent.

We have also reconsidered the linearity test procedure specifications
and, given the current quality of the available oxidized mercury gas
standards, have decided to increase the allowed measurement error for
the oxidized mercury standards to + 10 percent. We have not changed the
calibration drift specification of 5 percent of the span value as we
believe is reasonable as many installations of mercury CEMS have been
able to achieve this specification.

PS-12B

Comment: Several commenters (2855 and 2915) provided specific comments
about PS-12B.

Commenter 2855 provided the following comments:

EPA has mixed a PS with on-going quality assurance procedures making
this procedure unnecessarily complicated. EPA should develop an Appendix
F type procedure for on-going quality assurance (QA) and eliminate the
three section spike trap requirement for daily use.

Section 6.1.1’s substitution of three-section traps in place of
two-section traps is unnecessary. The addition of the third section is
used for QA purposes. This requirement should be moved to the Appendix F
procedure that EPA needs to develop for sorbent trap systems.

The third section spike trap should only be required when the duplicate
trains do not meet the RD specification, during the initial relative
accuracy test and for on-going QA such as quarterly audits.

Response: We recognize that the commenter is recommending that all
quality assurance (QA) procedures related to sorbent trap-based mercury
monitoring systems in PS-12B be moved to a separate procedure in 40 CFR
60, Appendix F; we agree that this approach is more consistent with our
prior performance specifications and we have revised PS-12B to remove
the on-going quality assurance procedures and have incorporated them
into Procedure 5. The three-section trap required by PS-12B provides a
routine quantitative indication of measurement performance analogous to
the daily span check performed on gaseous mercury CEMS.

Comment: Commenter 2855 said that when spikes are required, the
procedure should allow the use of liquid standard spikes that are
traceable to NIST.

Response: We do not allow the use of liquid standard spikes in PS-12B as
they are not representative of gaseous emissions of mercury.

Comment: Commenter 2855 said that this reference sentence in Section
1.2.2 should be deleted: Section 1.2.2. This specification is not
designed to evaluate an installed sorbent trap monitoring system’s
performance over an extended period of time nor does it identify
specific techniques and auxiliary procedures to assess the system’s
performance. The statement is incorrect. The fact that paired sampling
trains meeting a relative deviation (RD) specification are required is a
means for determining ongoing evaluation over extended period of time.

Response: We agree with the commenter and have removed Section 1.2.2
from PS-12B.

Comment: Commenter 2855 said that Section 8.1.1 should be changed to
read select a location that is representative of Mercury emissions.

Response: We agree with the commenter and have revised Section 8.1.1 of
PS-12B so that it is consistent with the corresponding section of
PS-12A.

Comment: Commenter 2855 said that Section 8.3 should be deleted because
the RATA procedure is redundant and unnecessary.

Response: It is agency policy to conduct relative accuracy testing of
mercury monitoring systems. These RATAs are used to confirm the
continuing accuracy and representativeness of compliance monitoring
system measurements.

Comment: Commenter 2915 said that their comments on Section 8.1.1 of
PS-12A apply to proposed PS-12B.

Response: Section 8.1.1 of PS-12B specifies only that the sampling
location must be representative of the stack gas concentration of
mercury with a suggestion to consider a location shown to be free of
stratification for mercury, SO2, or NOx.

Comment: Commenter 2915 said that in Section 8.2.3, for sources
calculating Mercury mass emissions, EPA proposes to require
determination of stack gas moisture content using a certified continuous
moisture monitoring system. This requirement is too restrictive. The
commenter suggested that EPA review the alternative moisture measurement
options provided in Part 75 at 75.11(b), 75.12(b) and Appendix K, 7.2.4.
Similar language should be incorporated into PS-12B, especially the
default moisture content and psychrometric chart look-up table language.
In addition to the alternative of using the moisture monitor and various
options defined in Part 75, the commenter stated that one or more of the
carbon trap monitor vendors has a technique for recovering the moisture
collected by the sampling train. That option should also be allowed. The
term certified continuous moisture monitoring system is undefined; the
commenter is not aware of a PS for certification of moisture monitors.

Response: We have revised Section 8.2.3 of PS-12B to remove the
requirement for continuous moisture monitoring system certification and
to allow for other moisture measurement options acceptable to the
Administrator such as those noted by the commenter.

Comment: Commenter 2915 said that in Section 8.3.2 – EPA proposes an
alternative relative accuracy specification of 0.5 μg/m3 if the
reference method value is less than 2.0 μg/m3. This alternative
relative accuracy specification is inconsistent with the alternative
specification in proposed PS-12A, Section 13.3 and there is no reason
for the inconsistency. In addition, there are considerable field data to
show that both PS-12A and PS-12B relative accuracy specifications are
unrealistic based on present day technology and will result in a
significant number of test failures.

Response: We have revised Section 8.3.2 of PS-12B to make it consistent
with the corresponding section of PS-12A and, as noted previously, we
have revised the relative accuracy specification in PS-12B to 20%.

Comment: Commenter 2915 said that in Section 11.2, this section of
PS-12B requires the analysis of the first glass wool plug in the trap,
while PS-12A states that Method 30B does not require the analysis of the
first glass wool plug (see Section 8.5.2 of PS-12A). If the first glass
wool plug is included in the analysis, particulate Mercury will be
measured not just vapor-phase Mercury. The commenter agrees with the
PS-12A requirement because the intent is to not measure Mercury that may
be on the particulate matter. It is clearly stated in Section 1.0 that
the intent is to measure vapor-phase Mercury emissions.

Response:  The first glass wool plug of the Method 30B sorbent tubes
must be analyzed. We have clarified Section 8.5.2 of PS-12A to clarify
that the sentence stating that the “filterable portion of the sample
need not be included when making comparisons to the CEMS results” is
only applicable to Method 29 and Method D6784-02.

Appendix F, Procedure 5

Comment: One commenter (2855) agreed with Section 4.1 requiring that
corrective action or adjustment shall be performed when the CD exceeds
twice the PS-12A limit, and Section 4.3 specifying out of control
criteria as CD checks results exceeding (a) twice the PS-12A limit for
five consecutive daily periods, or (b) CD check result exceeding four
times the PS-12A CD limit.

Response: EPA notes the commenter’s support.

Comment: One commenter (2855) said the use of oxidized calibration
standards for gas audits are redundant with System Integrity Checks
required as part of the quality control requirements in Section 3.0 and
should be deleted.

Response: We have provided some flexibility under Section 3.0 of
Procedure 5 in establishing the acceptance criteria for the weekly
system integrity check; we, therefore, on a quarterly basis require a
more extensive two level accuracy audit using oxidized Hg gases that
must meet specified criteria.

Comment: One commenter (2855) said that the language in Section 5.1.2
(2): “At a minimum, the audit gas should be introduced at the
connection between the probe and sample line” is not appropriate and
should be removed.

Response: We agree with the commenter and have removed this sentence
from Section 5.1.2(2) of Procedure 5.

Comment: Commenter 2855 said that quarterly gas audits will be performed
using the elemental Mercury and oxidized Mercury calibration gas
generators of the CEM system. Section 5.1.2 (3) requires use of NIST
certified or NIST Traceable calibration materials for gas audits.
However, NIST traceable gas standards will not be available may not be
available at the required levels for several years.

Response:  As noted previously, 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 µg/m3
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.

s ± 5.0 μg/m3.

Response: This was an inadvertent error; the specification in Section
5.2.3 (2) was intended to be ± 0.5 μg/m3 and the section has been
revised to reflect this.

Comment: Commenter 2915 said that in Section 1.1, in the second
paragraph EPA states that, Procedure 5 covers the instrumental
measurement of Mercury as defined in PS-12. It is not perfectly clear on
first reading that Procedure 5 is not applicable to Mercury measurement
systems using PS-12B. PS-12B is performance-based and is
self-validating. A sentence should be added making that fact clear.

Response: As noted in response to a previous comment, we have decided to
revise PS-12B to remove the on-going quality assurance procedures and
instead incorporate them into Procedure 5; thus, Procedure 5 will now be
applicable to both PS-12A Hg CEMS and PS-12B monitoring systems when
called for by the applicable regulation.

Comment: Commenter 2915 said that in Section 5.1.2(3), as proposed, the
section states, Use elemental Mercury and oxidized Mercury...... This
should be changed to read, Use elemental Mercury or oxidized
Mercury......... It is not necessary to use both elemental and oxidized
Mercury for this test because both are NIST traceable.

Response: We disagree with the commenter’s recommendation; we believe
it is important to obtain information on system linearity and a
quantitative accuracy assessment for both species on a regular basis.

Comment: Commenter 2915 said that in Sections 5.1.3 and 5.2, EPA
proposes to require the analysis of performance audit samples, except
during audits following corrective action. However, EPA provides no
information regarding the availability of such samples or explanation
regarding how the results will be used. The commenter does not believe
such samples exist for Mercury and notes that audit samples are not
necessary for Methods 30A and 30B because they are performance-based
methods and are, therefore, self-auditing. This language also is
inconsistent with the statement in Section 1.2 that Procedure 5 also
requires the analysis of audit samples concurrent with certain reference
method (RM) analyses as specified in the applicable RMs. EPA should
revise this provision to include similar language that makes clear, for
example, that audit sample analysis is not required for Methods 30A and
B, because those methods do not require them. For other methods, EPA
should explain the requirement and make clear that it does not apply if
audit samples are not available.

Response: We agree that this language on use of performance audit
samples is not necessary in this procedure and have removed those
references.

Comment: Commenter 2915 said that in Section 5.2.3, this section sets
out the criteria for excessive audit inaccuracy. Based on the
commenter’s experience, all of the specifications are too stringent.
For RATAs, EPA refers to PS-12A. For Gas Audits, EPA proposes an
alternate specification of ±5 ppm. Because Mercury CEMS do not read in
ppm (they read in μg/m3), this specification makes no sense. This
alternate specification should be changed to ±1.0 μg/m3. For RAAs, EPA
proposes the greater of ±15 percent of the three run average, or ±7.5
percent of the applicable standard. These specifications are too
stringent and EPA has provided no data to support them. EPA should
revise the standard to ±20 percent of the three run average or 10
percent of the applicable standard.

 μg/m3, and (3) we have revised the specification in Section 5.2.3(3)
for the relative accuracy audits to be ±20 percent of the three run
average or the equivalent of 10 percent of the applicable standard,
whichever is greater, as suggested by the commenter.

Comment: One commenter (2915) said that in Section 5.3, EPA proposes to
require a source to revise its QC procedures or modify or replace the
Mercury CEMS if excessive audit inaccuracy occurs for two consecutive
quarters. EPA provides no basis for this requirement or data to support
its criteria for excessive audit inaccuracy. The consequences of failing
performance specifications should be identified in the applicable
regulation. In addition, the requirement to, modify or replace the
Mercury CEMS is much too onerous. There are only two vendors that have
Mercury CEMS that are compatible with these proposed regulations and the
technology is what it is. The performance of both vendors is similar and
requiring a change from one vendor to the other makes no sense.

Response: We disagree; if the mercury CEMS was capable of passing the
initial RATA, then with modification, repair, or a change in the QC
procedures, the system should be able to continue meeting the QA
criteria.

Comment: One commenter (2837) stated that PS-12A and Procedure 5 appear
to be written around the perceived capabilities and limitations of a
specific CEMS technology. It is important to correct this because as
written, these two documents have the potential to fix future technology
and emission standards to the capabilities of the measurement technology
around which they were written. This is most apparent in those sections
where the specifications unnecessarily require certified NIST traceable
gas standards or generators. The commenter provided further detailed
discussion of this issue. The commenter requested that EPA modify both
PS-12A and Procedure 5 to remove requirements that are technology
specific and replace them with performance based requirements.

Response:  The use of NIST traceable mercury gases for system
calibrations, checks, and linearity determinations is not specific nor
exclusive to any particular type of CEMS technology. We disagree that
that their use is unnecessary; in fact, we believe that use mercury
gases (in particular NIST traceable gases) is the only way to routinely
confirm that the mercury in the stack gas matrix is being quantitatively
transported from the stack to the instrumental analyzer.

2.5.5	Impacts

Costs

Comment: One commenter (2855) states that the industry believes
installation and certification of HCl CEMS as currently proposed is
expected to cost between $225,000-$250,000 plus another $30,000 for
initial certification. The total costs for ongoing QA are unknown as
facilities cannot install and certify HCl CEMS using Performance
Specification-15. Additional costs for add on controls (e.g., wet
scrubbers) to meet the extremely low concentration levels proposed are
expected to cost upwards of $20,000,000.

Response: EPA estimated the cost of complying with the final HCl
emission standards as the cost of installing and operating add-on
control equipment and the cost of installing and operating continuous
emission monitoring equipment. Total capital and annual costs for HCl
CEMS were estimated to be $144,000 first time (or capital) cost, and
$43,000 per year annual cost. Total capital cost of a wet scrubber for a
new 1.2 million tpy kiln, including the cost of CEMS, was estimated to
be $25.1 million per kiln. Cost of control for HCl is discussed further
in, “Summary of Environmental and Cost Impacts for Final Portland
Cement NESHAP and NSPS.”

Plant closures

Comment: Many comments were received regarding the effects of the
proposed rules on plant closures.

Commenters 2298, 2483, 2506, 2507, 2651, 2653, 2654, 2661, 2667, 2671,
2672, 2811, 2812, 2813, 2824, 2832, 2833, 2863, 2886, and 3218 stated
that without the use of a subcategory within the MACT rule allowing EPA
to address the naturally occurring mercury in limestone of western
cement plants, then plants like the Durkee Cement Plant in rural Oregon
may have to close. The commenters explained that the loss of the Durkee
Plant jobs would have a substantial impact on the local economy.

Commenter 2832 stated that the CAA does not give EPA the authority to
regulate, diminish, or steal away the financial and quality of life
advantages that a community may have because of local desirable natural
mined materials. Inclusion of emissions associated with such mined
materials would effectively be a ban on their use and would exact a
great toll on local communities.

Commenter 2830 has determined that three of their existing plants could
be forced to close with many of their wet kilns at high risk of closure,
and high capital cost may also close long dry kilns should the 2009
proposed rule be implemented.

Commenters 2830, 2840, 2841, 2863, 2886, 2916, and 3218 stated that
should cement facilities close because of the proposed rule, the lost
domestic supply of cement will be offset by imports, creating global
increases in mercury and greenhouse gas emissions if these foreign
plants are not regulated to the same degree, and increased
transportation emissions. Commenter 2841 added that there would be an
increase of NOx, volatile organic compound (VOC), PM, carbon monoxide
(CO) and CO2 emissions from the transportation of raw materials.

One commenter (2786) disagreed with comments suggesting cement
production will shift overseas due to weaker standards. The commenter
cites a United Nations effort to develop a global legally binding
instrument on mercury by the year 2013.

Commenter 2867 also disagreed with the severity of industry projections
regarding plant shutdowns and a lack of capacity resulting from
implementation of the proposed rules. The commenter suggests that many
facilities will be able to meet limits with closer review of raw
materials or by implementing less-expensive dust shuttling. In addition,
it is possible for the industry to mitigate the claimed impact by
encouraging cement equipment designers to tackle these issues and
disseminating successful mercury reduction techniques throughout the
industry.

Response: As noted in the preamble, EPA carefully considered the
possibility of creating different subcategories of cement kilns with
respect to mercury emissions, including subcategories based on the
mercury concentration of the limestone. For the reasons stated in the
preamble, we decided not to create this type of subcategory.  We
anticipate an increase in imports of only10 percent in 2013, which
translates to a decrease in domestic revenues of 3 million metric tons.

The preamble also notes that EPA is forbidden by law from considering
costs in determining MACT floors. NRDC v. EPA, 489 F. 3d 1364, 1376
(D.C. Cir. 2007); National Lime, 233 F. 3d at 640. Although one of the
overall goals of the Act is to protect and enhance the quality of the
Nation’s air and resources so as to promote the public health and
welfare and the productive capacity of the population,” CAA section
101(b)(1), this overall goal does not somehow authorize EPA to adopt
floors that either consider costs (overall or otherwise) or to base
floors on other than what best performers achieve. Further information
about the economic impacts of this rule can be found in the preamble and
the project docket.

Wasting CKD to reduce mercury emissions

Comment: Several commenters (2144, 2824, and 2845) commented on the
practice of shuttling or wasting CKD and its ability to reduce mercury
emissions.

Commenter 2845 stated that EPA should not consider the removal, or
wasting of CKD a form of mercury control, nor should it be considered
akin to a mercury control device. The purpose of wasting CKD is to
ensure product quality. No plant wastes CKD with the intent of reducing
emissions. The level of mercury removed by wasting CKD also varies
significantly from plant to plant; to consider this practice as a form
of mercury control is highly questionable. Furthermore, as EPA
recognizes, wasting CKD generates solid waste, and cement companies
often have significantly reduced their solid waste generation by
decreasing their wasting of CKD. Accordingly, the Proposal should not
require companies to waste CKD or engage in dust shuttling.

Commenter 2845 stated there are other limitations to reducing mercury
emissions by removing or wasting baghouse dust. Instead of returning the
dust (i.e., uncalcined limestone), it can be continually bled off to the
finish mill and intermixed with cement. This is known as dust shuttling.
However, there are limitations to how much of this baghouse dust can be
intermixed with cement. Specifications on the quality of cement limit
the amount of baghouse dust that can be intermixed with cement. Dust
shuttling also results in additional carbon dioxide emissions from each
ton of cement produced because companies cannot utilize limestone
addition (the dust would use up all the insoluble residue and/or loss on
ignition available). The commenter includes expanded comments on this
topic as an appendix entitled Mercury Emission Control by Removing
Baghouse Dust.

Commenter 2144 disagreed with the reference at page 21150 of the FR
Notice that removal of all baghouse dust when the raw mill is down will
yield only 4% reduction in mercury emissions. The commenter states that
mercury control is actually negative during the raw mill-off condition
considering a plant-wide material balance.

Commenter 2144 agrees with EPA’s statement that the use of CKD wasting
to reduce mercury emissions is site specific. The commenter added that
with the construction specifications allowing 5 percent inorganic
processing additions, the CKD or filter dust will often not need to be
wasted and has been shown to improve or least not to degrade the cement
in areas where the raw materials are low in alkali.

One commenter (2824) stated that criteria for determining the
best-performing 12 percent of existing sources for mercury emissions
should either not include kilns wasting CKD and scrubber dust or the
contribution in the dust should not be subtracted from the input.
Otherwise, depositing high mercury waste in landfills is considered
best-performing. Wasting dust requires more fuel and feed which
generates increased CO2 emissions. This is an adverse cross-media
impact.

Response: The commenter is not correct in implying that intent is
relevant in determining if an activity which affects emissions can be
considered as a means of control. All that matters is the effect on
emissions. National Lime II, 233 F. 3d at 640. We realize that this is a
site-specific issue, and the percent removal obtained by shuttling or
wasting CKD ranges from very low to up to 80 percent. Some of the
best-performing kilns in the MACT floor waste CKD. It will take more
extreme facts than those presented here to justify invalidating a
practice that removes emissions from some of the best performers.

Comment: One commenter (2844) stated that there is no demonstrated ACI
system that will simultaneously control mercury and hydrocarbons. In
light of that uncertainty, the industry is faced with taking a chance on
an unproven technology or using multiple technologies (ACI plus a
scrubber plus an RTO) that represent huge investments which have not
been analyzed fully by EPA.

Response: The reason EPA has long adopted the interpretation that the
existing and new source MACT floors are to be applied on a HAP-by-HAP
basis are that a whole plant approach likely yields least common
denominator floors, that is floors reflecting mediocre or no control,
rather than performance which is the average of what best performers
have achieved.  See the preamble to the final rule for more discussion.

Concerns over effectiveness of control technology

Many comments were received on the limited emission reductions
achievable with the installation of add-on control devices.

Effects of mercury speciation

Comment: One commenter (2844) stated that the standards are not
achievable, and EPA has used unrealistic assumptions about the control
effectiveness of individual technologies. Wet scrubbers are ineffective
controls for elemental mercury, and the effectiveness of ACI is a
function of mercury speciation. In the utility industry, the collection
efficiency ranges from less than 20 percent to greater than 90 percent.
If the concentration of oxidizing agents is low, a high percentage of
the elemental mercury is not effectively captured by the sorbent. There
have been only limited mercury speciation data collected at cement
plants, but what data there are indicates the mercury speciation at the
inlet of the particulate control device ranged from almost 100 percent
to near 0 percent elemental mercury. Depending on plant configuration
and flue gas composition, standard ACI will not provide a sufficiently
high level of mercury control to allow certain cement kilns to meet the
proposed rule. The cost of ACI is high, and may not be cost effective
for facilities where the pre-control emissions are very small, and the
emission reduction will be small.

Response: We set the standards based on what has been achieved in
practice in the industry, with MACT floors established based on actual
emissions data for the best-performing sources. We used statistical
analysis and a 30-day averaging period to account for variability, such
as the situations cited by the commenter.

Activated carbon injection

Comment: One commenter (2845) stated that EPA overestimates the emission
reductions from mercury controls. EPA states that most if not all cement
facilities will have to install some form of mercury control in order to
meet the proposed mercury rule. Currently, the best available control
technology for mercury is considered to be ACI. However, the commenter
argues that the effectiveness of ACI is site-specific, based on utility
industry studies and that should be the case for the cement industry as
well. The commenter provides discussion about the technical issues
surrounding the five primary factors that affect mercury collection
efficiency using ACI: mercury speciation; temperature profile; residence
time of the particulate control device; type of ACI used; and flue gas
composition (particularly sulfur trioxide (SO3)).

Commenter 2845 stated that the effectiveness of ACI for mercury control,
based on limited mercury speciation data, will be very site-specific. It
also appears that the concentrations of elemental and oxidized mercury
are very site-specific. As a result, as has been recognized in the
utility industry, ACI is not the magic bullet that will always control
mercury at a high level. Mercury control strategies will need to be
tailored for each plant. Such strategies may include one or more of the
following: installation of a polishing baghouse; use of treated carbons
or enhancement agents; change in the strategies for handling of CKD
(wasting or not wasting); installation of a wet scrubber; evaluation and
testing of more experimental types of mercury control technologies.

According to commenter 2845, all of these strategies will be expensive,
and there is no guarantee that ACI or any configuration will be adequate
to demonstrate compliance with the proposed mercury limit for a
significant number of cement facilities.

Commenter 2845 stated that EPA does not consider the adverse impact that
ACI will have on the way CKD is handled by the cement industry. Industry
has been striving to utilize CKD by either returning the CKD to the
cement kiln, or beneficially utilizing it. To ensure the quality of CKD
and to maintain the ability to recycle the CKD back to the system, it
may be necessary to install a polishing baghouse. The polishing baghouse
would introduce new problems, including lower than expected air-to-cloth
ratios resulting in a larger footprint, self-ignition in the baghouse
hoppers, and an increase in fugitive emissions, all of which increase
installation and operating costs.

Response: The pilot test data we have available for ACI systems showed
mercury removal of 90 percent, and we conservatively used 80 percent
removal in our analysis. We considered the installation of a polishing
baghouse and included it in our analysis, as well as the use of a wet
scrubber. The standards do not require that facilities install a
particular type of emission control (e.g., ACI). Facilities will need to
decide for themselves which control strategy is best for them, that will
account for site-specific factors and allow them to obtain the level of
emissions control needed to meet the numerical standard. Furthermore, we
do believe that the test data from the electric utilities industry is
transferable to this industry and that the commenters have not provided
any technical basis for their comments other than a discussion of
potential issues.  EPA knows of nothing that would preclude these
technologies from operating effectively in sequence.

Wet scrubbers

Comment: Several commenters (2844, 2845, and 2900) stated that EPA did
not fully consider the issue for wet scrubbers and mercury capture.
Commenter 2845 worked with EPA in 2008 to study mercury reductions
achievable through wet scrubbers, and includes the report in their
comment.

According to commenters 2844, 2845, and 2900, the only mercury captured
by a wet scrubber is oxidized mercury. Elemental mercury is insoluble in
water and, therefore, passes through the scrubber. Therefore, the
effectiveness of wet scrubbers for mercury removal is almost entirely
based on the form of mercury entering the unit. There is a wide range in
mercury speciation for the cement industry. As a result, the theoretical
level of mercury control obtained by already having or installing a wet
scrubber will be different for each plant. There is also a phenomenon,
known as mercury reemission, related to mercury/scrubber chemistry that
may reduce the effectiveness of a wet scrubber to capture even oxidized
mercury. Reemission is a result of mercury reduction chemistry in wet
scrubbers, where oxidized mercury is reduced to insoluble elemental
mercury. Mercury reemission is primarily a result of sulfate/sulfite
chemistry. Testing conducted at four cement kilns utilizing a wet
scrubber revealed that all four of the plants tested showed elemental
mercury concentrations at the outlet of the scrubber to be greater than
the inlet concentrations. Commenter 2845 stated that the pH in the
scrubber may affect reemission and data as to the impact of pH on
reemission are very limited and appear to be conflicting.

According to commenters 2844, 2845, and 2900, EPA states that oxidized
mercury will be captured by the scrubber but, as has been found both in
the utility and cement industries, depending on the flue gas composition
and type of scrubber, this is not always the case. To make any blanket
statement as to the effectiveness of wet scrubbers to control mercury
would be premature and site-specific. There are proprietary additive
technologies that are available from companies such as Babcock & Wilcox
which may help mitigate this problem but will result in increased costs.
It should be noted that none of these additive technologies have been or
are currently being utilized or even tested in the cement industry.
Therefore, the effectiveness of these additives for the cement industry
is unknown. Also, these additive technologies are not relevant for use
in establishing the existing source floor because no such database for
the use of this type of technology exists.

Commenter 2900 provided data from two stack tests, in order to show the
difficulty of achieving compliance with the new mercury limits, and the
variability in run to run emissions during stack testing.

Commenters 2833 and 2840 stated that EPA’s analysis has not identified
add-on technology within existing kilns that is effective for all forms
of mercury. Only 3 of the 5 existing cement kilns equipped with wet
scrubbers are among the 11 lowest mercury-emitting kilns, primarily due
to low mercury concentrations in the limestone. One of the kilns
equipped with a wet scrubber provided no mercury control at all.

Commenter 2863 stated that several approaches to reduce mercury
emissions had been considered at the commenter’s site:

Reduction of limestone mercury content by selective mining. The
commenter provided mining data showing the variability and lack of
predictability of mercury content in the commenter’s limestone quarry.

The addition of a wet scrubber to the commenter’s ACI system. The
commenter notes that wet scrubbers only control oxidized mercury as
elemental mercury is not water soluble. Given that testing at the
commenter’s kiln indicated that up to 70 percent of the mercury is in
the elemental form, a wet scrubber is not going to provide a material
amount of additional control. The ACI system is predicted to control
high levels of the oxidized mercury as well as promote the oxidation of
the elemental mercury. Therefore, no material additive benefit would
come from the use of a wet scrubber.

A potential small boost in control efficiency may be obtained by
bleeding a percentage of the dust collected in the primary baghouse into
the finished product. The concept behind dust shuttling is that a
percentage of the uncalcined limestone caught in the primary baghouse,
and the mercury condensed on it, is continually bled off to the finish
mill rather than the raw mill, and intermixed with cement. The
usefulness of this procedure is limited by the commenter’s product’s
performance standards.

Another conceptual possibility for reducing mercury emissions from
affected sources that include quarries with elevated mercury levels is
to implement some sort of limestone scrubbing. The commenter is not
aware of any commercially available systems that could reduce limestone
mercury content.

Response: For mercury control, ACI systems are the most likely control,
not wet scrubbers. Our analysis did not rely on wet scrubbers as the
primary control for mercury emissions. In cases where wet scrubbers are
used for HCl control, the scrubber may provide additional control for
mercury. Wet scrubbers may also be helpful in reducing mercury emissions
for a couple of high-emitting kilns. We recognize the usefulness of dust
shuttling as a method of mercury control is site-specific, but it is one
of the control strategies to be considered.

Support mercury control strategies

Comment: Several commenters (2144, 2786, 2867, and 2928) provided
comments in support of EPA’s assessment of the use of add-on controls
and other methods to reduce mercury emissions.

Commenter 2867 provided discussion of several instances of the use of
dust shuttling, ACI, wet scrubbers, and other Mercury control
strategies. The commenter recommends that EPA:

Help foster actual demonstrations of filter dust shuttling with
temperature management.

Help foster the demonstration of catalytic oxidation or oxidant
injection to make mercury more collectable.

Help foster demonstrations of ACI or lime injection with dust shuttling
and temperature control and determine ways to make this combination less
expensive.

Commenter 2928 supported the use of ACI for mercury control saying that
it has a long commercial track record in removing mercury from emissions
of coal-fired power plants and waste-burning facilities.

Commenter 2928 provided information about a German cement
manufacturer’s patent for an ACI system based on powdered furnace
coke, coupled with dust withdrawal/shuttling, temperature control, and
mercury oxidation by sulfur doping.

Commenter 2928 stated that the use of selective catalytic reduction
(SCR) in combination with scrubbers for removal of mercury is a
technically feasible and economically reasonable control technology for
cement plants. The commenter noted that the 2006 Assessment of NOx
Emissions Reduction Strategies for Cement kilns – Ellis County written
by five cement industry experts for the Texas Commission on
Environmental Quality concluded SCR was an available technology for
newer dry kilns and a transferable technology, for older wet kilns,
meaning it is commercially available and could reasonably be expected to
work on those wet kilns.

Commenter 2144 recommended that EPA foster the demonstration of
catalytic oxidation or oxidant injection to make Mercury more
collectable. Technologies include SCR and potentially peroxide injection
into gas conditioning towers. The commenter has data demonstrating the
efficacy of mercury reduction in the coal-fueled power industry when SCR
is used to control NOx emissions. SCR technology has been commercially
demonstrated in the cement industry at Solnhofen, Germany, Monselice,
Italy and Sarche di Calavino, Italy. It has excellent multi-pollutant
possibilities including reduction of THC and dioxin/furan (another HAP
regulated under the Cement MACT rule). The commenter provided an
internet link to a report evaluating the use of SCR in the cement
industry.

Commenter 2928 stated that the use of scrubbers technically feasible and
economically reasonable control technology for mercury removal from
cement plant emissions.

Commenter 2928 stated that the use of front end controls can also be
used to control mercury emissions. Technology that removes mercury from
coal that is being fired for fuel increases the efficiency of the coal
by 30 to 50 percent, reduces mercury by up to 70 percent, and decreases
SOx and NOx.

Commenter 2786 stated that it is possible to achieve mercury reductions
in a cost effective manner, citing the Maryland Department of the
Environment’s agreement with Lehigh Cement Company at their Carroll
County facility to reduce emissions by 80 percent by 2012.

Commenter 2142 stated support for EPA’s focus on good particulate
control as a way to achieve good mercury control. The commenter provided
two summary tables of mercury emission reductions by non-cement source
categories and stack test results for mercury emissions from coal-fired
power plants.

Response: EPA acknowledges the support of the commenters of EPA’s
assessment of the use of add-on controls and other methods to reduce
mercury emissions and agrees that many of the suggested control methods
are cost effective for various installations. However, we should note
that MACT standards must be based on the best-performing sources in the
category or subcategory, not a specific control technology.

Increased CKD waste as result of mercury control strategies

Comment: One commenter (2898) suggested that EPA address the potential
increase in cement kiln dust waste or reuse. EPA discusses the potential
for an increase in the amount of CKD wasting at cement plants as a
result of mercury emissions control practices. 74 FR at 21165. However,
the status of CKD that is not reused in the production process is
uncertain. EPA has yet to establish standards for the management of
cement kiln dust. EPA last published a Notice of Data Availability
concerning cement kiln dust in July 2002 and intimated that it would
propose new standards for the management of CKD, but has taken no
further action on the subject. In light of the potential for increase in
the practice of CKD wasting and the uncertainty surrounding the
treatment of CKD, the commenter urged EPA to consider adding
requirements to the rule to prevent or control the potential additional
solid waste or to initiate a separate rulemaking to address the proper
handling of CKD.

Response: EPA is making no determinations as to the status of waste
generated as a result of this rule, nor making any determinations as to
management practices for cement kiln dust. In assessing the costs of the
rule for purposes of EO 12866, EPA has conservatively assumed that
wastes will be landfilled and estimated the costs of doing so as part of
the estimated costs of the rule.

Mercury standards not supported on public health basis

Comment: One commenter (3067) stated that EPA’s public health basis
for the proposed mercury requirements was not scientifically supported.
The commenter requested that EPA provide information about: what percent
of methyl mercury that is consumed by fish comes from cement plants; how
much of the industrial contribution of mercury is converted to methyl
mercury in soil; if there are studies suggesting that lowering mercury
emissions would lower methyl mercury levels in fish; and EPA’s
supporting evidence that these rules provide health benefits.

Response: According to the 2005 National Emissions Inventory, mercury
emissions from cement kilns represent 18% of the industrial
(non-electrical generating units) mercury inventory in the U.S. (U.S.
EPA, 2005). This final rule would reduce mercury emissions from cement
kilns by a substantial amount. The rate of mercury methylation is
spatially variable, depending on the specific aquatic chemistry of the
deposition location.

For this final rule, EPA modeled mercury deposition from cement
facilities using the Comprehensive Air Quality Model with extensions
(CAMx) model. This model converted mercury emissions to ambient mercury
levels and mercury deposition. In the final RIA, EPA provides maps of
the reduced mercury deposition. Due to time and resource limitations,
EPA was unable to model the conversion from mercury deposition to
methylmercury to human health effects from consuming
methylmercury-containing fish. For more information regarding the health
effects from mercury, please consult EPA’s mercury website at
HYPERLINK "http://www.epa.gov/hg/" http://www.epa.gov/hg/ .

However, EPA notes that standards under section 112 (d) are
technology-based, not risk-based. Thus, the decisions as to the level of
the standards is based entirely on the criteria set out in sections 112
(d)(3) and (d) (2), which do not include consideration of risk. EPA did
take into account that mercury is a potent neurotoxin, and the magnitude
of mercury emissions from particular cement kiln sources, in determining
not to create a subcategory for high mercury emitting sources with high
concentrations of mercury in their limestone. EPA believes it legitimate
to consider these factors in determining whether to exercise its
discretion whether or not to exercise subcategorization authority, since
these factors relate to the ultimate object of section 112 (d) of
reducing emissions of hazardous air pollutants.

Least cost control options may not yield expected SO2 emission
reductions

Comment: One commenter (2144) provided links to state air agency and
trade group presentations regarding control options. The commenter noted
that cement companies will gravitate to the least-cost options and it is
not a given they will choose mercury or HCl reduction strategies that
will actually yield the magnitude of reductions expected by EPA in SO2,
a pollutant not regulated under §112.

Response: EPA recognizes that any SO2 emission reduction obtained as a
result of this NESHAP rulemaking is a co-benefit of the control
technology selected either for Hg or HCl. EPA recognizes the multi
pollutant interactions and co-benefits of this rulemaking and how a well
planned integrated control strategy can maximize the environmental
results while optimizing the cost invested by a facility to comply with
such regulation.

Restrict use of quarries with high mercury limestone

Comment: One commenter (2893) recommended that EPA should not allow any
new high mercury content limestone quarries to be mined, and that no new
high mercury content limestone quarries be allowed to be mined at kiln
locations in which an old limestone quarry has been mined out.

Response: The new source standard for mercury reflects the performance
of the best controlled existing kiln. If a new kiln locates at a quarry
with high mercury levels but can still meet this limit, they are allowed
to do so under section 112 (d).

2.6	THC Standards

Comment: Several commenters (2898, 2928) recommended that EPA adopt the
proposed MACT floor for THC.

Response: EPA has revised the proposed THC floor and standard based on
more representative data. See “Development of the MACT Floors for the
final NESHAP for Portland Cement”.

2.6.1	Legal Issues

Use of CEMS data results in unlawful standard

Comment: One commenter (2901) stated that basing the THC on CEMs data
leads to an unlawful standard. The commenter’s concerns are that:

Using daily averages significantly reduces variability, leading to an
unlawful standard.

There is a flaw in using continuous data under normal operating
conditions to set a standard.

The currently proposed 7 ppmv THC standard cannot be achieved by the top
performers. The commenter provided an analysis based on the daily data
for two sources that EPA used to set the floor, resulting in one
facility not meeting the standard 20 percent of the time.

Response: The standard in the final rule has been revised from proposal
based on additional data. However, all of the data on which the standard
is based comes from CEMs, so there is no basis for stating that use of a
CEM makes the standard more stringent. The data also are gathered from
periods of well over a year, and so can reliably be used to assess
monthly variability without use of statistical extrapolation.

Unlawful rescission of standards for Greenfield sources

Comment: One commenter (2864) stated that EPA is unlawfully attempting
to rescind the THC standards for greenfield sources in the proposed
rule. EPA established MACT standards over 10 years ago when it first
promulgated the NESHAP for the cement industry. 64 FR 31898 (June 14,
1999). The commenter stated that EPA may revise MACT standards under two
provisions: §§112(d)(6) and 112(f). EPA has not undertaken the
necessary analysis under either provision to conclude that new
greenfield sources should become subject to either of the THC standards
EPA has proposed.

Response: As noted in the preamble to the final rule in connection with
EPA’s decision to amend the PM standard, EPA does not read section 112
(d)(6) as the exclusive means of amending a MACT standard, particularly
when that standard does not properly represent MACT. The standard was
based on siting considerations only, and did not consider THC emission
levels of the best controlled similar source as required by law. The
standard is now anomalously higher than the existing source standard,
confirming that it does not represent a proper MACT standard. EPA
therefore sees no bar to amending it to establish a standard properly
based on section 112 (d).

2.6.2	Adequacy of Floor Determinations (Existing and New)

5 best performing sources vs 12 percent

Comment: One commenter (2911) stated that EPA correctly based its THC
floor on the 2 best performing sources.

Response: We agree that a literal reading of the stature results in a
floor based on the two best performing sources based on the THC CEM data
available at proposal

Comment: Many comments were received on the adequacy of the data and the
analysis used in the development of the MACT floor for THC.

Commenters 2841, 2858, 2859, 2863, 2864, and 2889 stated that EPA’s
use of 2 kilns as the basis for the THC limit for existing sources was
inappropriate. The commenters stated that EPA should not set the THC
MACT floor for existing cement plants using data from less than five
sources. According to the commenter, EPA proposed to use the limited
data set for two kilns due to a very narrow interpretation of
§112(d)(3). Because there are more than 30 sources in the source
category and EPA only has THC data for 14 kilns, it is apparent that EPA
seized on the parenthetical part of the language in §112(d)(3)(A) to
conclude that it can set the THC MACT floor based on only two kilns (12
percent of 14). According to the commenter, EPA made no attempt to use
its authority under §114 of the CAA to require cement plants to monitor
their emissions of THC in order to provide EPA with sufficient data to
establish the MACT floors based on the best performing 12 percent of
sources in the category. Congress clearly intended for EPA to obtain
data from an adequate number of sources to be able to set realistic and
achievable standards. Some of this commenter’s facilities comprised a
significant part of the THC MACT floor yet the proposed standards are
not achievable for most of the kilns owned by the company without the
installation of expensive controls such as regenerative thermal
oxidizers (RTO) to control THC emissions.

Response: EPA and the industry agree that it is most appropriate to use
THC CEM data to set the floor because this data provided the most
representative information on long term emissions performance. EPA made
a concerted effort to obtain additional THC CEM data subsequent to
proposal of this rule. Unfortunately, the data was received too late in
the process to be thoroughly analyzed. In addition, the use of this
additional data would not have substantially changed the outcome of the
floor determination for most kilns. We continue to believe that the
literal reading of the statute required us to use the best performing 12
percent of the facilities of which we have emissions data, which, in
this case, is two kilns.

Variability incorrectly analyzed

Comment: Commenter 2864 stated that EPA incorrectly analyzed variability
in calculating the proposed THC MACT floor. The commenter stated that
CEMS data cannot account for all of the long-term variation in a given
quarry, which extends over several hundred acres with a life of over 100
years. The commenter stated that EPA’s analysis using 30 days of data
results in a MACT floor that cannot be achieved over the long-term. EPA
must identify a MACT floor for each HAP and source category based on
emission levels achieved by the best-performing 12 percent of existing
sources, and must demonstrate with substantial evidence that the chosen
floors represent a reasonable estimate of the performance of the
best-performing units. EPA’s use of the UPL model to calculate the
MACT floors for THC violates this requirement because it does not
represent a reasonable estimate of the performance of the best
performing sources.

Commenter 2864 also critiqued EPA’s method for calculating
variability, and provided an alternative calculation after collecting
additional long-term data for the lowest emitting five sources. The
commenter stated that the UTL provides a much better estimate of the
99th percentile adjusted for variability than the UPL. The commenter
stated that EPA should have used the actual 99th percentile to establish
a MACT floor because the data set contains long-term data.

Commenter 2889 requested that EPA review the additional data from the
recent §114 request or provide detailed information that demonstrates
that the 11 kilns for which data are available do, in fact, represent
the entire cement industry.

Commenters 2841, 2845, 2858, 2859, 2863, 2874, and 2889 stated that EPA
relied upon a data set that included a combination of long-term (470-880
data points) and short-term (31-35 data points) CEMS data, from 12
kilns. This resulted in data from the two lowest emitters being used to
establish the existing MACT floor. One of the two sources used in the
floor calculation had only 35 data points, or the equivalent of six
30-day rolling averages. To compensate for this lack of data, EPA used
the UPL statistical approach to project long-term variability. EPA is
now in possession of more than one year of CEMS data for 16 kilns. While
this still represents a rather small portion of the entire cement
industry, the commenters agreed that it is a statistically
representative database for purposes of setting existing and new source
floors. In addition, the commenters recommend that EPA use the
calculation of the 99th percentile rather than the UPL to establish the
MACT floor levels.

Commenters 2859, 2845, 2863, and 2874 stated that with the additional
THC CEM data provided to EPA since proposal, EPA now has a sufficient
amount of data and may not need to apply any statistical analysis to
account for variability and simply use the available emissions data.
However, given the new data and considering that the new data sets
account for variability in the 5 best performing sources, the revised
THC standard should be 27 ppmv dry at 7 percent oxygen for existing
sources and 24 ppmv dry at 7 percent oxygen for new sources. However,
the data does not show whether the limestone reserves available to units
in the existing data pool or other units have significant variations in
the nature and amount of organics. Furthermore, where either coal mill
and/or raw material dryer exhaust are co-mingled with the kiln stack
emissions, it is important to determine whether either case warrants
subcategorization. Although the PM standard in the proposed NESHAP was
based on a limited data set of 3-hour stack tests, short-term test will
not address the variability issues. Commenter 2874 stated that EPA
should base the THC standard on substantially more data.

Response: In response to comments, we re-evaluated the statistical
analysis and methodology used for the proposed rule and made changes to
improve it. The changes we made and why are discussed in the preamble to
the final rule and in supporting documentation in the docket and include
why we continue to believe the use of the 99th percentile UPL is the
most appropriate statistical approach, how we accounted for variability
(including intra-quarry variability), and other changes to the analysis
since proposal. We disagree with the commenters who said 30 days of data
are insufficient, and we continue to believe that the 30 data points
provided from 30 days of sampling of all kiln inputs for 89 kilns is a
robust sample of the population of cement kilns and adequate to
characterize the variability encountered at each individual kiln,
especially as supplemented in the final rule to account for documented
inputs from outside the 30-day sampling period and with pooled estimates
of intra-quarry mercury variability (both of which are then put into the
UPL equation as part of the s squared term).

Subcategorization

Comment: Many commenters (2844, 2845, 2859, 2863, 2864, and 2874)
suggested that EPA consider subcategorization due to the variations that
can be found in raw materials, source configurations, and processes in
which the current data from the 5 best performing sources does not
accurately illustrate how emissions may vary in different kiln
configurations and other sources. Commenter 2864 urged EPA to collect
data from all cement plants in order to properly subcategorize, and
delay setting THC MACT standards until that time. The commenters
suggested that EPA gather long-term THC CEMS emission data for the
following reasons:

For some kilns, high THC levels can be attributed to a combination of
the level of organics in the limestone, the form of the organics in the
limestone, and a kiln configuration that has one or more source of
organic releases downstream of the kiln (in particular in-line raw mills
and in-line coal mills venting to the main stack.). While a few of the
units with THC CEMS have high THC emissions, the data on raw material
(e.g., limestone organics) have not been collected or correlated for
these kiln emissions. Commenter 2845 submitted a white paper (Appendix
9) addressing these issues as part of their comment.

EPA has assumed that any raw material dryers should meet the kiln THC
limit; however, EPA has no data to show that this is an appropriate
extension of kiln THC measurements. There are limited data that suggests
that these dryers have lower volume and higher THC emissions than kilns.

Separate standards for standalone raw mills operated with supplemental
fuel firing, raw material dryers, and those kilns with high THC levels
due to organics in the co-located quarry may be appropriate. This cannot
be done without a strong database of THC CEMS readings and feed material
characteristics supporting the best possible presentation on the need
for one or more added subcategories for THC limits.

There is no data to suggest that organic HAP at standalone raw mills
that use supplemental fuels and coal mills that use kiln or cooler gases
are emitted.

The proposed organic HAP standards did not account for the various
volatiles that are added to the kiln exhaust as a result of contract
with the ground coal in a coal mill. Commenter 2863 testing documented
that a considerable quantity of organics are added to the stack exhaust
when the kiln gases are routed through the coal mill. Although, the
majority of the organics are methane, the non-methane, non-ethane
hydrocarbon, and the total hydrocarbon emissions exceeded 100 ppmvd on
average.

EPA should consider collecting additional data to determine if
subcategorization is appropriate to address THC emission variability
from different physical characteristic of kilns or different
characteristics of raw materials.

Response: See preamble to final rule.

Background THC levels not accounted for

Comment: One commenter (2889) stated that EPA has not taken into account
ambient background THC levels and the variability in ambient background
THC levels that inherently affect measured stack concentrations. Ambient
levels of methane and ethane will increase the measured THC by as much
as 15 percent. The commenter stated that additional data are needed
concerning the multi-day and multi-week increases in ambient air THC
levels due to forest and agricultural fires.

Response: We disagree with the commenter in that the MACT floor
determinations were based on demonstrated performance testing and THC
monitoring from several plants over extended time periods. These
long-term monitoring test data included ambient background THC levels
and their associated variability.

THC standards are adequate

Comment: One commenter (2144) stated that the proposed 30-day emission
standards of 7 and 6 ppm for existing and new kilns, respectively,
appear to be adequate. These values equate to roughly half of the BACT
VOC limits when relying on THC as the surrogate. According to the
commenter, at many kilns the primary contributors to THC emissions are
additives acquired as wastes from other industrial sources such as steel
mill scale. Excessive VOC/THC emissions problems in Florida were
typically solved by acquisition of less oily mill scale. Another
solution is to introduce the oily additives directly into the kiln
system where they can be thoroughly burned thus avoiding low and medium
temperature THC evolution from colder parts of kilns and preheaters.
This commenter agreed with EPA regarding regenerative thermal oxidation
(RTO) or ACI particularly when naturally existing kerogen in native raw
materials contributes to THC emissions. The commenter also noted that
the Polysius Environmental Technology (POLVITEC) available since the
early 1990’s includes a coke filter that has been demonstrated to
reduce THC and SO2 while storing mercury until it can be removed to a
very high degree by filter dust shuttling.

Response: See the preamble to the final rule explaining the basis for
the final THC standard.

Shorter averaging period

Comment: One commenter (2142) supported a shorter averaging time (24
hours or less) with regard to hydrocarbon emissions, but agreed with
EPA’s proposed limits and 30-day averaging time.

Response: EPA acknowledges the commenter’s support.

POM and naphthalene not adequately addressed

Comment: One commenter (2828) expressed concern that the proposed MACT
rules do not establish MACT limits or properly evaluate control
technologies that could greatly reduce emissions of polycyclic organic
matter (POM) , naphthalene, or dioxins/furans. The commenter agreed with
EPA that limits should be established for organic hazardous air
pollutants, and the choice of VOC or total non-methane hydrocarbons
(TNMHC) seem like reasonable options as surrogates, but emissions of POM
and naphthalene are likely to be unrelated to emissions of the other
organic HAPs. The commenter stated that traditional organic HAPs are
primarily driven by hydrocarbons in the raw material mix. Variations in
the hydrocarbon composition of the limestone seemed to be the largest
contributor to variability in organic HAP and THC emissions.

Because the processes resulting in POM and naphthalene formation are not
the same as those resulting in VOC or benzene, toluene, ethylbenzene,
and xylene (BTEX) compounds, cement kilns that are low VOC and BTEX
compound emitters may be high emitters of POM and naphthalene. The
commenter encouraged EPA to move forward with establishing final MACT
rules proposed in this rulemaking, including rules for organic HAPs, but
suggested that EPA consider the difference in the formation mechanisms
when deciding how to establish MACT standards for all organic compounds,
and potentially separate POM and naphthalene from the other organic
compounds in establishing MACT standards and appropriate monitoring
protocols. Further, EPA should undertake additional study of POM and
naphthalene emission rates from cement kilns throughout the U.S., to
determine if there is tight correlation between emissions of these
compounds and the other organic HAPs. If not, EPA should then establish
POM and naphthalene MACT standards, independently of the standards for
the other organic HAP compounds.

Response: EPA reviewed test reports for emissions data on THC and
organic HAP. Based on those test data, we identified specific organic
HAP that were measured with sufficient frequency that we could and at
levels that would allow us to establish an emission limit for organic
HAP as an alternative to the THC limit. Naphthalene emissions were
included in the analysis of organic HAP as an alternative to the limits
for THC. It is regulated under the final rule in that the definition of
organic HAP specifies naphthalene as one of the organic HAP that must be
measured to determine compliance with the organic HAP limit. In
evaluating emission test reports, the test results for POM were not
sufficient to include as one of the organic HAP that must be measured.
However, we believe that the limits for THC and organic HAP serve as
surrogates for POM and that POM emissions will be reduced as a result.

Organic HAP alternative

Comment: Regarding the organic HAP alternative to THC, several
commenters (2845, 2859, and 2874) stated that the organic HAP standards
should be raised to reflect the commenter’s proposed THC standards of
27.4 ppmv and organic HAP standard of 6.6 ppmv (24 percent of 27.4) for
existing sources and 24 ppmv and organic HAP standard of 5.7 ppmv (24
percent of 24) for new sources.

Commenter 2863 stated that the proposed THC standard of 7 ppmvd for
existing sources and 6 ppmvd for new sources is inadequate and
requested that EPA not revise the organic HAP standard until it has time
to better evaluate existing data and that a separate subcategory for
kiln exhaust gases passed through an indirect fired, inline coal mill.
Also, the volatility of the coal being used should be considered in
establishing standards for inline coal mills. As part of the final rule,
EPA should include a specific exclusion for coal mills from coverage
under subpart Y NSPS so plants will not have to deal with dual and
potentially conflicting regulations

Commenters 2859, 2845, 2863, and 2874 objected to the option of
demonstrating compliance with the alternative equivalent organic HAP
emission limit rather than the THC limit for companies that have
naturally low hydrocarbon emissions, very low organic HAP emissions, and
use Method 320 to demonstrate organic HAP compliance for the following
reasons:

The organic HAP standard does not account for variability in THC levels
when using Method 320 to demonstrate compliance. The organic HAP rate
may be substantially lower than the 2 ppm indicated in the proposed
rule; however, the concurrent THC concentration levels may be
substantially higher than the 6.7 ppm even if testing during typical
conditions.

Units should be permitted to extrapolate the same factor for organic HAP
level and THC compliance limit set during the organic HAP compliance
demonstration test.

As an alternative, kilns should be given an opportunity to establish and
take into consideration THC variability before the THC limit is set
during the organic HAP compliance demonstration test and be allowed the
option to install CEMS before the organic HAP compliance demonstration
test in which THC and organic HAP emission rates could be collected for
6 months prior to the demonstration test. The operator would have to
demonstration that operating conditions are representative of the
6-month period at the time of the stack test and once the compliance is
demonstrated EPA could set the application THC limit at 99 percent
variability for that 6-month period for the unit.

Facilities that choose to comply based on actual organic HAP should have
the option to demonstrate compliance whenever THC emission exceeds the
limit set during organic HAP compliance demonstration test because
limestone deposits are not homogenous creating the possibility that new
high THC seam might be encountered and thus raising the possibility that
THC will go up but organic HAP emissions may remain constant. The
facility should be given 6 months to retest for organic HAP if the
alternative THC limit is exceeded and if the kin complied with the
organic HAP limit, no violation should be found related to the high THC
emissions.

Commenter 2844 recommended that EPA adopt the proposed THC compliance
alternative for sources whose organic HAPs are a low percentage of their
total THC. This compliance alternative is important for kilns whose THC
emissions may be higher due to other factors but who have established
that HAPs are a low percentage of those emissions.

Commenter 2889 stated that EPA does not reference the study that
provided the basis for the HAPS/THC ratio. Considering the importance of
this alternative standard, this study should be cited. It should also be
evaluated to determine if the 0.24 HAP/THC ratio is, in fact,
representative of the cement industry.

Response: See discussion of THC and organic HAP in the preamble.

Emission limits for raw material dryers

Comment: Several commenters (2845, 2859, 2863, 2874, and 2910) stated
that it is inappropriate to set the same emission limits, and controls,
for kilns and raw material dryers and that EPA establish MACT floors for
new and existing sources of raw material dryers using data from the
dryers. Cement kilns and raw material dryers differ in the following
ways:

The heat source in the kiln is designed to reach high temperatures for
calcining and combing raw materials to make clinker; the heat source in
the raw material dryer is designed to remove free water from the raw
materials. of the heat source in the raw material dryer is for removing
free water from the raw materials. Because the temperature within the
kiln system and tower is above 600 degrees F, hydrocarbons present in
the feed volatilize. In contrast, the temperature in a raw material
dryer is significantly lower, resulting in a completely different
profile of hydrocarbons volatilized.

The volume of gasses drawn through kiln systems is 10 times greater than
the volume of gasses passing through the raw material dryer.

The proposed THC limits for dryers expressed at 7 percent oxygen are
equivalent to a 1 ppm actual emission concentration standard at the
material dryer.

Facilities may intermittently use raw material dryers. Commenter 2910
stated that the cost to install the required monitoring equipment and
possible emissions control devices would prove to be more costly than
EPA has assessed.

Based on the substantial differences between kilns and raw material
dryers, there is no basis to simply assign the proposed kiln THC
standard to raw material dryers. EPA should withdraw the limit and more
closely evaluate actual raw material dryer emissions in order to confirm
that these units generate organic HAPS to a level necessitating
regulation and if they do establish the data necessary to support an
appropriate limit. Commenter 2845 has initiated a process to gather
additional THC emissions data, data to more thoroughly assess raw
material dryer THC emission performance, and organic HAP data for
standalone raw material dryers. These data will assist EPA is developing
more appropriate standards.

Commenter 2845 stated that when defining the THC limit for raw material
dryers at major sources in §63.1346(a), the proposed rule does not
include the alternate option of complying with a total organic HAP
limit. The commenter suggested that the language should be updated to
reflect the same option as allowed in (b) for area sources.

Response: We did not have sufficient data, information, or justification
to subcategorize raw material dryers as suggested by the commenter. We
were working with a limited data set of kilns and dryers and the MACT
floor is based on the performance of the two lowest emitting kilns. The
additional THC data was received too late to be considered in this
rulemaking. These data were not submitted to EPA until mid-June 2010,
virtually too late for any consideration, much less considered in the
MACT floor analysis and subcategorization.

Regarding the alternate total organic HAP limit for raw material dryers,
we have corrected the final rule to state the alternate option of
complying with a total organic HAP limit applies to raw material dryers
at major and area sources.

Subcategorize based on coal grinding system

Comment: One commenter (3218) requested that EPA consider developing
subcategories that reflect the different configurations for coal
grinding systems. There are two main configurations, where gases are
vented from the coal system directly to atmosphere out of a separate
stack and where coal system gases are vented to atmosphere after being
comingled with exhaust gases from the kiln and vented out of a common
stack.

Response: EPA did consider subcategories based on the coal grinding
configurations suggested by the commenter but decided against creating
separate subcategories. See the preamble discussion under the THC limits
for more information on EPA’s decision.

2.6.4	Compliance Assurance

Relative accuracy test audit

Comment: One commenter (2622) stated that the PS included in the
proposal for certifying the VOC monitor does not require a Relative
Accuracy Test Audit (RATA). The proposal would also apply Appendix F to
the VOC monitor, which requires annual RATA. There is an inconsistency
in not requiring a RATA for certification, but requiring it annually
after certification.

Since the proposal calls for RATA on the VOC monitors when the emission
limits are low (emission limits less than 10 ppm), EPA will need to set
a low emission criteria for passing a RATA. The commenter expressed
concern that 20 percent of the reference method or 10 percent of the
emission limit will be too restrictive.

Response: The final rule has been revised to require the certification
of the CEMS using Performance Specification 8, which does require a
Relative Accuracy Test Audit.  The performance criteria have not been
changed.

Monitoring at low concentrations

Comment: Several commenters (2844 and 2845) stated that monitoring THC
at the 6-7 ppm level will present significant challenges, noting that
hydrocarbon CEMS have been used successfully on hazardous waste burning
kilns but at concentrations greater than three times those required by
this proposed rule (i.e., 20 ppm). Furthermore, when a hazardous waste
kiln approaches the limit of 20 ppm, it triggers an automatic waste fuel
cut-off, which ensures that the facility is in compliance with the
standard as there are no hazardous wastes in the combustion chamber
under higher hydrocarbon concentrations. This approach will not be
available for non hazardous-waste burning cement kilns as the THC
concentration approaches or exceeds 6-7 ppm. EPA should raise the limit
to account for the variability associated with the raw materials and the
inability to change raw material input to comply with the standard. Once
installed it is expected that the CEM up-time and data availability will
be less than the 90 percent required by EPA due to the learning curve
that will be associated with operating and maintaining these devices.
The commenter stated that hot/wet straight extractive systems are
difficult to maintain on a continuous basis due to moisture condensation
in heated sampling systems, often long calibration times, and monitor
wear and tear from the corrosive environment. Some of the challenges
that will need to be addressed include: the difficulty of monitoring
hydrocarbons at very low concentrations, the accuracy of calibration
materials as 1 ppm propane standards are the lowest available, and the
variability of hydrocarbon compounds in the limestone used to
manufacture cement.

One commenter (2889) stated that the variability in flame ionization
detectors (FID) response factors for organic compounds changes the
stringency of the THC standard for some kilns. It is well known that THC
monitors using FID have different response factors for different organic
compounds. Cement kilns having organic compounds with a higher set of
response factors will be subject to more stringent emission limits than
kilns having organic compounds with lower response factors. Considering
that there are very little data concerning the ranges of specific
organic compounds in the kiln effluent gas stream, the impact of the
variations in response factors cannot be determined. Additional data are
needed to determine if the THC standards of 6 ppmvd (new kilns) and 7
ppmvd (existing kilns) is equitable.

Response: Based on data received since proposal, we have revised the THC
limit to 24 ppmvd which should address the commenters’ concerns about
monitoring at very low concentrations. The standard is based on data
from different kilns with different constituents, which addresses
variability concerns. Finally, with the change to PS8, sources are not
restricted to use of FID is they do not work as well as needed in
certain applications.

Stack testing for monovent facilities

Comment: One commenter (2888) requested that EPA allow monovent
facilities to stack test for THC, using EPA approved methods, on the
same 30-month frequency as required for Dioxin/Furan testing under the
current PC MACT.

Response: We remain convinced that CEMS are the best choice for
continuous monitoring. Sources with monovents can install stacks to
accommodate their use.

Testing to comply with speciated organic HAP alternative standard

Comment: Several commenters (2844 and 2845) stated that the Fourier
Transform Infrared Spectroscopy (FTIR) Method 320 and the American
Society for Testing and Materials (ASTM) Test Method D6348 are not
sufficiently sensitive to quantify the 1-2 ppm of total organic HAPs for
companies wishing to speciate organic compounds. Because a single test
method is not available for the organic compounds EPA has identified and
because of the low concentration levels, EPA must be flexible in test
method selection and allow use of appropriate methods to quantify and
sum these compounds. It is anticipated that at least 3 separate test
methods will be required to capture the low concentration of organic HAP
to sum to 1 or 2 ppm aggregate.

Response: As stated above, we have raised the level of the THC limit
which should address concerns about low concentrations. We have
carefully considered detection limits when setting the standards; a more
detailed discussion of this issue is presented in the preamble.

Comment: One commenter (2844) stated that a THC alternative option must
address THC variability for those units meeting the organic HAP
alternative limit. The commenter recommends stack testing for organic
HAPs at the same interval as that for dioxin/furans. Under the proposed
rule, a new THC limit would apply based on the level at the time of the
test. The commenter provided the following options for compliance
demonstration limits, with the suggestion that a kiln operator would be
able to choose between the three:

Demonstration of operating conditions consistent with test conditions
and good engineering practices. The ongoing compliance demonstration
would be based on two operating conditions that are indicators of
organic HAP emissions at the time of the stack test, with subsequent
continuous monitoring of those two parameters: the temperature at the
exit of the precalciner and the oxygen content of the exhaust at the top
of the preheater.

Extrapolation to set the revised THC limit. The revised THC limit is
based on the total organic HAP measured during demonstration testing,
extrapolated to the level of compliance and then extrapolating the
average THC value recorded during the total organic HAP test to the
proportionate level.

Accounting for measured THC variability when setting the revised THC
limit. The kiln owner installs the THC CEMS in advance of the stack
testing and gathers data for at least 6 months prior to the stack test.
At the time of the stack test, the operator must demonstrate that the
operating conditions are consistent with that 6 month period. Once
compliance is demonstrated, the applicable THC limit will be at the 99%
of variability for that 6 month period for that unit.

The commenter also suggested that if the alternative THC limit is
exceeded, the operator should be given six months to retest for organic
HAPs; if the organic HAPs are compliant in the retest, there is no
violation related to the high THC reading.

Response: The MACT floor determinations were based on demonstrated
performance testing and THC monitoring from several plants over extended
time periods. These long-term monitoring test data included ambient
background THC levels and their associated variability

Comment: One commenter (2845) stated that companies that have low
hydrocarbon emissions and low organic HAP emissions may elect to
demonstrate compliance with the speciated HAP portion of the rule and
that a new THC limit would apply based on the level at the time of the
test. However, because THC levels are variable, it could mean that 50
percent of the time the THC will be recorded over the limit even though
the performance of the unit is unchanged. According to the commenter,
there are at least 2 options, extrapolation or accounting for the THC
variability, that could be used to show practical THC limits along with
allowing the kiln operator to select the most appropriate option.

Response: Companies that elect to comply with the speciated HAP portion
of the rule should collect any background or previous test information
that would allow them to conduct their testing in a worst-case scenario
for their particular operations. The issue described by the commenter is
a key reason for having a 30-day compliance period – where any given
day the measured levels will be above or below the average. Sources also
have the option to retest if they believe the previous testing was not
representative.

Comment: One commenter (2844) requested that EPA defer promulgating a
final THC standard until more adequate data has been gathered, but urged
EPA to finalize the Alternative Compliance Option for THC as
expeditiously as possible.

Response: EPA has gathered significantly more data since proposal and
believes it ample to set the final standard.

Measuring THC from raw material dryer

Comment: One commenter (2845) stated that the process and combustion gas
composition of the kiln system and dryer are completely different. In
the kiln, the main constituents are nitrogen and carbon dioxide. Oxygen
content of the kiln exhaust gas is typically below 2 percent at the kiln
exit and about 7-10 percent at the stack. In the raw material dryer the
main constituents are nitrogen and oxygen, with oxygen levels typically
above 19 percent. Also, if the THC concentration in the raw material
dryer is adjusted to 7 percent oxygen as proposed for the kiln, it would
require the actual emission concentration to be less than 1 ppmvd THC to
meet the proposed limit of 7 ppmvd. The accuracy of the THC analyzers
available for monitoring is not sufficient to determine compliance with
a 1 ppm standard. (1ppm THC at 19 percent oxygen = 7.3 ppm at 7 percent
oxygen). Calibration gases are manufactured at a lower concentration of
1 ppm propane, and demonstrating compliance at the level corresponding
to the lowest level calibration standard generates an unknown degree of
inaccuracy.

Response: We received no data indicating that using the same limit for
raw material dryers as used for kilns was infeasible, or that it would
otherwise allow us to set a different THC emissions limit for raw
materials dryers. Therefore, in these final amendments we are setting
the THC emissions limit at the same level as the cement kiln’s, which
is 24 ppmvd measured as propane.

However, because raw material dryers have high oxygen contents due to
their inherent operation characteristics (and not due to the addition of
dilution air), referencing the raw material dryer standard to 7 percent
oxygen would actually result in a more stringent standard than for
cement kilns. For example, given the typical oxygen contents of kiln
exhaust (7 to 12 percent), a kiln just meeting the THC limit of 24 ppmvd
would have an actual stack measurement of approximately 16 to 24 ppmvd.
If the raw material dryer standard is referenced to the same oxygen
level, they would have to meet a measured THC limit of approximately 3
ppmvd. For this reason, we are referencing the oxygen level of the
standard for raw materials dryers to 19 percent oxygen, which is the
typical oxygen level found in the exhaust of these devices.

Flow rate monitoring

Comment: One commenter (2845) stated that EPA should not require
volumetric flow rate demonstrations during speciated HAP or THC testing.
The proposed standard is a concentration based standard, so no flow rate
monitoring data are needed for reporting in units of the standard. At 40
CFR 63.1349(b)(4)(iv), EPA incorrectly requires that the flow monitoring
system be evaluated according to procedures in Part 75, therefore this
requirement should be deleted.

Response: The commenter identified an error in the proposed standard,
which has been corrected in the final standard.

PS-8A

Comment: One commenter (2845) stated that PS-8A should be modified for
low concentration measurements. PS-8A was developed for cement plants
burning hazardous waste. PS-8A has an explicit span requirement of 100
ppm as propane. The calibration drift and calibration error requirements
are 3 percent (3 ppm) and 5 percent (5 ppm) respectively, which are
very near the proposed compliance level. The proposed THC standard is at
6 and 7 ppmv dry at 7 percent oxygen. The criteria contained in PS-8A
will not evaluate the acceptability of the THC monitoring systems with
adequate accuracy to demonstrate compliance with the proposed standard.
Therefore, PS-8A must be completely re-worked to evaluate low
concentration level monitoring systems, without simply (and arbitrarily)
lowering the span and calibration drift specifications.

Response: The final standard has been revised to specify use of PS-8,
instead of PS-8A, because PS-8 is a better fit for this application. The
span for the RATA is specified as 40 ppm and the reference method is
established as EPA Method 25A.

Need for Appendix F procedure

Comment: One commenter (2845) stated that EPA should develop an Appendix
F Procedure specific for hydrocarbon CEMS. Although an Appendix F,
Procedure 1 was written for SO2, NOx and diluent CEMS (O2, and CO2), it
is not directly transferrable to a THC CEMS monitoring for compliance at
extremely low concentration levels. For example, a key element of
Procedure 1 is an annual relative accuracy test. However, PS-8A does not
include a relative accuracy specification and instead correctly relies
on calibration gas audits because there is no independent reference
method. Furthermore, the cylinder gas audit levels for Procedure 1 may
not be appropriate for a revised PS-8A, especially if multi-range
analyzers are necessary. Requirements at Appendix to Subpart EEE for
hazardous waste combustors contain quality assurance procedures for THC
and other CEMS used at these facilities. These procedures should be
modified for low-level measurements and appropriate requirements should
be developed for Subpart LLL sources.

Response: The proposal identified PS-8A as the monitoring performance
specification for THC monitoring through an oversight, and PS-8 is now
specified. Also, the rule language now proscribes the THC CEMS span
value as 40 ppm and the reference method for the RATA as Method 25A.
With these revisions and in view of the THC standard concentration
value, EPA is confident that the performance requirements of Procedure 1
of Appendix F are appropriate and can be met.

CEMS alternatives

Comment: One commenter (2844) stated that EPA should not require CEMS
but instead look to other effective monitoring methods that are more
practical and efficient. The commenter’s experience with a VOC
Analyzer (CEMS) was that the unit requires a lot of maintenance,
expense, and frequent repairs, resulting in increased downtime compared
with priority pollutant CEMS.

Response: We believe that CEMS are the best alternative to demonstrate
continuous compliance and that they are a demonstrated technology, as
well as the source for all of the data used to develop the standard.
However, we are always interested in the evolution of monitoring
technologies and will consider source-specific alternatives proposed
under the General Provisions.

Contradictory, erroneous requirements and clarifications

Comment: Several commenters (2845, 2859, and 2863) stated that numerous
areas of the proposed regulations include contradictory, erroneous, or
otherwise impractical requirements relating to compliance demonstrations
in the performance testing requirements and or monitoring requirements.
Comments are as follows:

The initial compliance demonstration procedures for total hydrocarbons
appear contradictory and should be revised to be consistent with the
proposed emission standards and 30-day rolling average for THC
emissions. Specifically, §63.1350(h)(4) states that daily average THC
concentration must not exceed the THC limit for new or reconstructed
facilities which is inconsistent with §§63.1343, 63.1346, and
63.1350(h)(2) and (h)(3). The initial performance demonstration should
be based on a properly calibrated and compliant CEMS and the initial
performance test result must be based on the calculated average THC
concentration for 30 kiln operating days. A definition for kiln
operating day must be established and must reflect a specified number of
hours of kiln or raw material dryer operation at normal production
conditions. Days with fewer operating hours than a kiln operating day
should not be included in the 30 day average.

The initial compliance demonstration procedures for total hydrocarbons
specifies a performance test duration and conditions that are not
appropriate. Section 63.1349(b)(4)(i) addresses initial compliance for
THC specifying a performance test duration of 24-hours, and calculating
the daily average THC concentration from the hourly averages during the
performance test. Furthermore, it states that initial compliance shall
be demonstrated by conducting separate performance tests for in-line
kiln/raw mills with the mill operating and with the raw mill off. This
would require the facility to run in a mill-off condition for 24 hours,
which is not possible. There should be no specification for separate
initial compliance tests for mill-on and mill-off for in-line raw mills.

The THC monitoring requirements for facilities complying with total
organic HAP limits are inconsistent with the averaging period of the
standard. Section 63.1350(r)(2) requires calculation of 3-hour average
THC concentrations and stating that the 3-hour concentration may not
exceed the average established during the initial performance test is
not consistent with the basis of the limit. The site-specific THC
emission limit is based on a 30-day rolling average and EPA should
correct this apparent discrepancy.

The testing to establish THC emission limits for facilities with in-line
kiln/raw mills that choose to comply with total organic HAP limits
should be simplified to require testing at the operating condition that
is appropriate for the particular plant. Section 63.1349(b)(4)(iii)
requires performance tests to establish site-specific THC emissions
limits corresponding to compliance with the emissions limits for total
organic HAPs. For kiln/in-line raw mills, this section specifies that
tests are to be conducted while the raw mill is off and while the raw
mill is operating. This could potentially create different THC limits
for the two operating conditions which becomes completely unworkable
since compliance with the resulting standard is determined on a 30-day
rolling average and will obviously contain both mill-on and mill-off
operation. EPA should clarify that the test is to be inclusive of both
mill on and mill off conditions and the full range of plant operations
including feed materials and fuels/fuel combinations in order to develop
a single alternate limit. EPA should not specify separate tests under
mill-on and mill-off conditions. Furthermore, where total speciated
organic HAP emission tests demonstrate that emissions are below the
emission limit, EPA should explicitly allow proportional extrapolation
of the measured HAP and THC values to determine the corresponding THC
surrogate compliance limit.

Section 63.1349(b)(4)(vi) states that emission tests to determine
compliance with total inorganic HAP limits shall be repeated annually
and this is inconsistent with other sections of the proposed rule
regarding the parameters to be tested and the frequency of the test, and
this section should be changed. The word inorganic appears to be a
typographical error and EPA should confirm that the phrase should be
total organic HAP. There are no requirements for performance testing of
inorganic HAP. The annual test requirement in this section also
contradicts the proposal where it explicitly states that stack tests for
organic HAP would be required every five years for kilns and raw
material dryers meeting the organic HAP alterative to THC to determine
the organic HAP component of their THC emissions. The proposal states
that annual organic HAP tests are not necessary, will be very costly,
and could be disruptive to plant operations. EPA should specify that
testing should be conducted at least every five years. The facility
should be permitted to conduct the testing more often than every five
years and reset the alternative limit if changes in the facility
materials or operations warrant such changes. In addition, because such
testing for the organic HAP could result in THC levels higher than the
previously determined alternate limit, the time period of the testing
should not be included in the rolling average for compliance.

EPA needs to add a formula to enable sources to weight the relative
emissions contributions to determine compliance when emissions occur at
two points. Many plants with indirect fired, in-line coal mills are
designed to vent directly to atmosphere. Compliance with the organic HAP
standard for a plant so configured should allow the combination of both
stacks given that they both constitute sources of kiln gases. These
commenters requested that EPA add to the rule a formula equivalent to
Equation 2 of 63.1349 whereby an affected source configured such as the
one depicted below can demonstrate compliance with the THC standard by
combining the concentrations from the main stack and the coal mill
stack.

Response: We have made several clarifications and corrections in the
final rule to respond to these comments, including:

Clarifying that the 30-day average is a rolling average,

Adding a definition of “kiln operating day,”

Raw mill off testing is required for the initial compliance test to
establish the site-specific THC level.

Removed paragraph 63.1350(r)(2), because this language is inconsistent
with the 30-day rolling average.

Replaced the reference to “inorganic” HAP emissions testing with
“organic” HAP emissions testing.

Clarified that organic HAP testing is to occur at least every 30 months
unless there are changes at the plant that warrant more frequent
testing.

Clarified that data collected during a performance retest need not be
incorporated into the existing 30-day rolling compliance average.

As described elsewhere, we agree with comments that the initial
performance test period should also be a 30-day average. Regarding the
comment requesting proportional extrapolation of the measured HAP and
THC values, we lack the data to establish such a provision. If a source
needs to expand its operating range, it should retest and establish a
new limit. Finally, the suggestion to add a formula to address combined
concentrations from the main stack and coal stack is not needed, because
of the concentration format of the standard. Such a formula is only
needed when the standard is in the form of a mass limit.

Comment: One commenter (2845) stated that the definition of total
organic HAP in section 63.1341 should be changed to add the reference to
test methods EPA Method 18 and ASTM D6420, and adsorbent based methods
or impinge train methods to test for total organic HAP for speciating
organic HAP.

Response: The final rule includes a higher THC value than proposed, with
the result that we do not think these additional methods are needed to
determine total organic HAP. However, a source is always able to request
an alternative method under the General Provisions.

Comment: One commenter (2845) provided the following suggestions and
clarifications to §63.1349(b)(4)(i):

Clarify that Alkali Bypass Stacks are exempted from CEM requirements for
THC.

A performance test for a source with a CEMS is duplicative and should
not be required.

The THC limit is a 30-day average (see §63.1350(h)(3)). Thus the
requirement for the duration of a performance test to be 24 hours
appears to be a typographical error.

This section appears to require a 24-hour test while the raw mill is
operating and a 24-hour test while the raw mill is not operating. A
typical downtime for a raw mill is 8 hours per day, one day per week. It
is not possible for the majority of in-line kiln/raw mill systems to
operate with the raw mill off for 24-hours.

Raw Material Dryers also have THC limits, and thus may be required to
use a continuous emission monitor and demonstrate compliance during raw
mill on/off conditions based on the proposed rule. It should be
clarified that the raw mill on/off condition is not needed for the
performance test of the Raw Material Dryer as it is not directly
associated with the kiln system.

This requirement should be removed or updated, according to language
provided.

Response: Alkali Bypass Stacks are subject to the standard.  However, we
have changed the final rule to allow the source to use the results of an
initial performance and subsequent compliance test as a surrogate for
continuous monitoring. We believe this is reasonable, given that the
majority of emissions are coming from the main stack.  We have clarified
that the initial compliance test for the CEMS is the initial 30-day
operating period.  For the raw material dryer, testing is not required
for the raw mill on/off conditions.

Comment: One commenter (2845) suggested that §63.1350(h)(2) and (3) be
combined into one requirement.

Response: We believe it is clearer to distinguish existing source
requirements from new and reconstructed sources in the format of the
standards.

Comment: One commenter (2845) suggested that the combustion system
inspection and reporting required under §63.1350(i), §63.1350(a)(3),
and §63.1354(b)(9)(iv)are no longer needed and can be removed. The
combustion system inspection was previously included in lieu of a THC
limit. Now that there is a THC limit, these inspection, recordkeeping
and reporting requirements are no longer needed.

Response: These requirements were actually part of the 1999 final rule
and were intended to help ensure compliance with the dioxin/furan
emissions limit. Because the dioxin/furan emission limit has not
changed, these requirements are still applicable.

Comment: One commenter (2845) included the suggestion that the EPA
should clarify that THC is on a propane basis and is a 30-day rolling
average at 7 percent oxygen.

Response: We agree and the final rule contains this clarification.

2.6.5	Impacts

Performance of controls overstated, impacts understated

Comment: Several comments (2841, 2844, 2845, 2864, and 2889) were
received that question EPA’s impact analysis for THC including the
performance of ACI and RTO, and adverse impacts associated with the use
of RTO.

Commenter 2845 stated that EPA has overestimated the use of ACI and
underestimated the use of RTO. According to the commenter, the EPA based
the ACI information on one single kiln that is no longer in service with
emissions and a configuration that was unusual for the industry. EPA
stated that 75 percent control should be achieved for cement kilns using
ACI because it was achieved for dioxin/furans in the incinerator
industry. The commenter disagreed with the comparison for the following
reasons:

There are substantial differences between cement kilns and incinerators
in operations, plant configurations, and flue gas composition as well
being two different industries, which can affect the effectiveness of
ACI for THC.

THC cannot be compared with dioxins/furans because THC also consists of
low carbon-based VOC (such as methane, ethane, and formaldehyde), which
has a substantial impact on the effectiveness of ACI.

Formaldehyde is not expected to be well controlled using ACI.

The ability of ACI to capture THC is total a physisorption-based
mechanism and therefore the effectiveness of ACI would be also entirely
mass-transfer-limited.

Lower THC concentrations would have to have an increase in the ACI feed
rate to match the sample percentage removed of THC at higher
concentrations.

The percentage of low-carbon THC is highly variable and the available
data indicates that low-carbon species can be <5 to >90 percent of THC,
which will impact the effectiveness of ACI.

Using ACI would have an adverse impact on the ability to reuse cement
kiln dust. Recycling the CKD would result in revolatilization of some of
the THC. Insufflation of a portion of CKD is possible for some kilns,