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National Emission Standards for Hazardous Air Pollutants for the Portland 

Cement Manufacturing Industry (Subpart LLL) and Standards of Performance 

for Portland Cement Plants (Subpart K) 

Response to Comments 

Final Reconsideration May 

2015 

List of Commenters 

EPA-HQ-OAR-2011-0817-0861 Portland Cement Association 

EPA-HQ-OAR-2011-0817-0862 Seth L. Johnson, Attorney, Earthjustice 

EPA-HQ-OAR-2011-0817-0863 Duplicate of EPA-HQ-OAR-2011-0817-0862 

EPA-HQ-OAR-2011-0817-0864 Vivek Kapur, Arizona Department of Environmental Quality 

Subpart LLL Portland Cement Manufacturing 

1. Reinstatement of the opacity standard 

Commenter 0862 states that EPA should reinstate the opacity standard removed in the 2010 

rule. The commenter explains that at the time, EPA was requiring bag leak detectors and CEMS 

and thought an opacity standard was “redundant.” 75 Fed. Reg. 54,970, 55,008/2 (Sept. 9, 

2010), and in 2013, EPA eliminated the CEMS requirement and replaced it with the stack test 

and CPMS operating limit regime now in place.78 Fed. Reg. 10,006, 10,010/1‐2 (Feb. 12, 2013). 

RESPONSE: EPA did not solicit comment on this issue, and thus a response is not legally required. 

However, if a response is deemed necessary, EPA disagrees that the existing source opacity limit 

should be reinstated. In the final 2010 rule, we stated that we were removing all opacity standards 

for kilns and clinker coolers because these sources will be required to monitor compliance with the 

PM emissions limits by more accurate means. Even though the final 2013 rule requires CPMS rather 

than CEMS, CPMS are much more sensitive in detecting increases on PM emissions than opacity (see 

75FR54989). Therefore the basic rationale in the 2010 rule (see 74FR21157) that an opacity 

standard is redundant, remains. 
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SO2 monitoring parameter issues (Comments 2 through 4): 

2. Rationale for the SO2 monitoring alternative. 

Commenter 0862 believes that the new SO2 monitoring alternative is not rationally explained, and that 

the explanation for why the scaling would maintain compliance with the HCl standard is lacking. 

RESPONSE: We agree with the commenter that some additional rationale would be helpful. 

The alternative monitoring proposed is not based on a surrogate relationship between SO2 and HCl. 

It is based on the fact that acid gas controls effectively remove the more reactive HCl in preference to 

SO2. Therefore, even if the SO2 emission rate increases, we can be reasonably certain that the HCl 

emissions level has not. The SO2 parameter is simply an indicator that tells us that the SO2 control is 

working properly, which indicates that HCl continues to be controlled (see docket item EPA-HQOAR2011-0817-0130). However, the available information on SO2 emissions indicates that they 

fluctuate over time. Without the scaling factor, facilities may be forced to continually retest HCl 

emissions unnecessarily due to these changes in SO2 emissions, even though, as previously noted, an 

increase in SO2 emission levels does not indicate a corresponding increase in HCl emissions levels. Even 

so, we recognize that there is some potential for a control system to lose its ability to control acid gases 

at all, so we have limited the scaling. We selected the 75% of SO2 emissions standard level as a 

reasonable level that will allow facilities some flexibility to operate their controls and meet their SO2

limits as their systems fluctuate normally, and place a reasonable action level on HCl, rather than 

assume that HCl emissions are always controlled to the level of the HCL limit if a wet scrubber or dry 

injection control system is in place. 

The commenter also stated that EPA has not explained why SO2 controls will be operating and also 

states that in the preamble, EPA indicates that scaling is an “alternative” that a source “may” use, but 

according to S 63.1349(b)(8)(vii), the source “must” set the SO2 operating limit using scaling if HCl stack 

test averages are below 75% of the HCl limit. 

RESPONSE: The EPA believes that facilities equipped with wet or dry scrubbers will be controlling for 

SO2. Although SO2 is not regulated under Subpart LLL, it is regulated under the New Source Performance 

Standard Subpart F for new sources who construct, reconstruct, or modify after June 16, 2008 (see 

75FR55035). Also, many states require SO2 control at Portland cement facilities to satisfy SO2 or PM 

attainment requirements. Thus, we believe there will be a subset of Portland cement facilities using SO2

controls, and these sources would have the ability to utilize the SO2 parameter to gauge HCl compliance. 

Relative to the discrepancy of the use of the word “may” in the preamble, and the word “must” in 

Section 63.1349(b)(8)(vii), the EPA agrees that there is a discrepancy and will correct this issue in the 

final rule under Section 63.1349(b)(8)(vii), and indicate that this is a compliance alternative, not a 

mandated mode of demonstrating compliance. 

3. Proposal to allow use of a scaling factor for SO2 CEMS operating limit for HCl compliance for units 

with scrubbers. 

Commenter 0861 agreed with the proposed approach to set the SO2 operational limit to mirror the same 

approach used for the PM CPMS. In addition, the commenter stated that an error was found in the 

definition of “R” in Equation 18 found in 40 CFR 1349(b)(8), where the EPA lists “ppmv at 7% O2”. This 

phrase should read “ppmvd at 7% O2”. 
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RESPONSE: The EPA agrees with this typographical error, and has made the correction in the final rule. 

4. Utilizing SO2parameter monitoring for kilns without SO2 controls 

Commenter 0861 agrees with the alternative scaling approach for HCl compliance, for units equipped 

with wet scrubbers or sorbent injection, but requests that the same approach be allowed for HCl 

monitoring at all kilns. 

RESPONSE: The EPA disagrees. The final rule does not allow the SO2 parameter approach for sources 

that demonstrate their HCl is 75% below the limit, but do not have a wet scrubber or sorbent injection 

system. As noted above, the basic premise that SO2 monitoring provides an indication that HCL 

emissions are being maintained at the level shown during the compliance test is that there is some type 

of SO2 control in place, and the fact that SO2 controls preferentially remove HCl. Without the scrubber 

device acting to remove the HCl from the gas flow, monitoring SO2 provides no assurance that the HCl is 

being maintained at the level it was at during the time of the compliance test. The scrubber is required 

for HCl removal; monitoring alone does nothing to remove HCl from the flue gas. Put even more 

directly, without a control device HCl emissions will not be controlled; SO2 monitoring in the absence of 

a control device does not alter this fundamental fact. 

5. Issue with revision of Section 63.1354(b)(9)(iv) 

Commenter 0862 stated that the proposed revision to Section 63.1354(b)(9)(iv), which removed the 

component of the regulation that required the results of the inspection to be reported, weakens the 

reporting requirement for no reason, since the results of the inspections matter to the public and should 

still be reported regularly to the agency. 

RESPONSE: The EPA disagrees with this comment. The proposed revision to 63.1354(b)(9)(iv) and the 

other revisions to Section 63.1354 are due to clarifications and further requirements needed for facilities 

to submit electronic summary reports semiannually to the Compliance and Emissions Data Reporting 

Interface (CEDRI). Inspection results for combustion system components must be kept on record and 

are available to the Administrator by request. These data are not compatible with the CEDRI electronic 

system, as it should be noted that provision 63.1354(b)(9)(iv) addresses inspections required under 

Section 63.1347(a)(3), which does not delineate what the component condition has to be, but rather 

requires that procedures be outlined for the inspection of the components to the combustion system. 

The procedures of how the inspection will be performed are the important parts of the operation and 

maintenance plan and must be approved by the Administrator. It should be noted that any deviations 

that would occur from a failed inspection are required to be reported semiannually under Section 

63.1354(b)(9)(vii); thus even though the outcome of the inspection is not reported, the deviation 

occurring from the failed inspection is indeed reported. We believe this system is sufficient to 

demonstrate compliance. Again, this information must be kept on record, and if needed can still be 

requested at the discretion of the Administrator, but not in electronic form.

6. Definition of Rolling Average 

Several commenters (0861 and 0862) stated that the proposed definition of rolling average was unclear, 

as the definition of rolling average proposed does not match the various forms of the standard found in 

the rule. 
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RESPONSE: The EPA agrees with the commenters that the rolling average proposed does not match the 

various forms of the standard found in the rule, and thus has revised the definition in the final rule. The 

final definition is listed below: 

"Rolling average means the weighted average of all data, meeting QA/QC requirements or 

otherwise normalized, collected during the applicable averaging period. The period of a rolling 

average stipulates the frequency of data averaging and reporting. To demonstrate compliance 

with an operating parameter a thirty-day rolling average period requires calculation of a new 

average value each operating day and shall include the average of all the hourly averages of the 

specific operating parameter. For demonstration of compliance with an emissions limit based 

on pollutant concentration a thirty-day rolling average is comprised of the average of all the 

hourly average concentrations over the previous thirty operating days. For demonstration of 

compliance with an emissions limit based on lbs-pollutant per production unit the thirty-day 

rolling average is calculated by summing the hourly mass emissions over the previous thirty 

operating days, then dividing that sum by the total production during the same period." 

7. Restoring the previous limits which apply until September 9, 2015 

Commenter 0861 stated that the previous limits that are in effect until September 9, 2015 should be 

added to the rule, instead of only a reference to the former federal register notice which contained the 

former limits, since it is not convenient for sources to locate and interpret former notices. 

RESPONSE: The EPA agrees with this comment that it is more convenient for sources to refer to one 

eCFR, and has published the former limits in the final rule. 

8. Performance Test Frequency 

Commenter 0861 stated that other NESHAP rules and the CISWI rule allow flexibility for an additional 

month around the due date for annual retesting. For example, instead of requiring annual testing within 

12 months, the test can be in up to 13 months (see 40 CFR 63.10006(f)) for the comparable provisions in 

the Utility NESHAP rule and 40 CFR 60.2150 for the comparable provision under the CISWI rule). The 

commenter believes this is very important because it allows one to book the testing for the same time 

each year rather than constantly moving the date up each year to be sure the testing is done before the 

12 month anniversary of the prior test. The commenter also believes that this helps one avoid having 

annual shutdowns conflict with annual tests. The commenter thus requests that the annual testing for 

PM under 40 CFR 63.1349(c) and for mercury from alkali bypass and coal mills under 40 CFR 1350(k)(5)(i) 

both be extended to 13 months. 

RESPONSE: We agree with the commenter that moving the date up each year in order to meet the 12 

month anniversary is not practical, and thus we are granting this request. We have revised this 

requirement in the final rule under 40 CFR 63.1349(c), which covers requirements both for 30 month 

testing and 12 month testing.

9. The use of a temperature parameter during startup and shutdown 

Commenter 0861 stated that the revised requirement for startup and shutdown (see 40 CFR 
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63.1346(g)(3) lacked clarity and was impractical. The concern was that the temperature threshold 

should only apply to injection systems and not all air pollution control devices. Also the commenter 

stated that the language suggests that the temperature would be determined as the gas stream reaches 

the control device, which might be read to mean the temperature at an injection system rather than at 

the PM control device inlet, which is what the commenter believes is relevant and indicated in the next 

sentence. The commenter also believes that an averaging time is needed for the temperature at the 

inlet to the PM control device to avoid a temporary change in temperature over the threshold of 300 

degrees which the commenter believes would result in non-compliance. The commenter also states 

that during shutdown, injection systems should not be operating. The commenter stated that when 

feed is pulled, flow to the particulate control device drops and any material injected may fall out and 

deposit, creating problems for restart. Instead the commenter believes the requirement should be to 

operate PM control devices only during shutdown. The commenter suggests revised wording to the 

proposed regulatory text to solve these issues. 

RESPONSE: The EPA agrees with the commenter that the proposed regulatory text lacked clarity. Thus, 

the EPA has agreed to include the clarifications found in the commenter’s proposed suggestions and has 

incorporated these revisions into the final regulatory text. The EPA also has clarified the text to include 

language that assures all HAP controls are being operated during startup and shutdown conditions. This 

language is included below: 

“(3) All dry sorbent and activated carbon systems that control hazardous air pollutants must

be turned on and operating at the time the gas stream at the inlet to the baghouse or ESP 

reaches 300 degrees Fahrenheit (five minute average) during startup. Temperature of the gas 

stream is to be measured at the inlet of the baghouse or ESP every minute. Such injection 

systems can be turned off during shutdown. Particulate control and all remaining devices that 

control hazardous air pollutants should be operational during startup and shutdown.”

10. Quality assurance of mercury CEMS data above the span value 

Commenter 0861 states that two of the three options for quality assurance of data above the span value 

are impractical and would result in unacceptable monitor availability. The commenter includes an 

explanation as to why two of the three options are not impractical and also includes an Attachment to 

the comment letter which the commenter states may be useful in understanding their comments (see 

docket item EPA-HQ-OAR-2011-0817-0861, Attachment A). The commenter believes that the option 

provided in (2) (iii) should be retained without substantial changes from what is currently in the rule, 

since the commenter believes this is the only option that is consistent with the scientific principal of 

checking the high level performance during periods of high level emissions, and in the commenter’s 

view, the option which minimizes the time for Hg CEMS equilibration and recovery and minimizes 

corruption of low level data. Also the commenter states that this is the only option that does not require 

high level calibration checks daily or weekly if no periods of Hg emissions above the span level occur and 

that this is the best technical option. 

Also the commenter states that the meanings of the proposed minor wording changes to (2)(iii) are 

ambiguous. The comment believes that replacing “be of” with “target” to imply that there is some 

additional tolerance relative to the 50 to 150 percent range, that the word “expected” conflicts with 

“measured”, and also states that because (2)(iii) allows the above span check to be performed “within 
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24 hours before or after” the above span period, the commenter interprets that “expected” is inserted 

to accommodate above span checks conducted prior to the above span period. Also the commenter 

states that the word “measured” should be deleted to avoid conflicting interpretation, and that basing 

the requirement of the “expected” value rather than the “measured” value is consistent with the new 

option (2)(ii). The commenter proposes edits to the proposed text for this issue, and also suggests edits 

to 2(iii) and a new paragraph is suggested. 

The commenter further states they support EPA’s proposal of the new option provided in (2)(ii) to 

perform a single high level “linearity” check weekly, as an alternative to (2)(iii), since this option 

is easy to initiate from the DAS or the CEMS controller as a scheduled sequence. The comment 

believes it could be coordinated to occur during planned raw mill maintenance periods and 

does not require complex new DAS programming. However, the commenter states that it 

explicitly requires the operator to regularly expose the Hg CEMS to Hg concentrations greater 

than the expected highest one-hour average, which the commenter believes will necessitate 

the greatest CEMS equilibration and recovery times. According to the commenter, when such a 

check is performed during mill on operation, the large concentration difference will result in the 

longest period of invalid data. 

The commenter continues to comment on the new option provided in (2)(ii) and believes it should be 

modified to allow the use of certified reference gases with concentrations less than “greater than your 

highest expected concentration” to provide additional flexibility and a more representative calibration 

check level. The commenter gives an example, that a target concentration of 75% of the highest hourly 

average measured concentration may be more representative for sources with few measurements at 

the very highest levels, and recommends that EPA add the underlined phrase below. 

“Conduct a weekly “above span linearity” calibration challenge of the monitoring system using a 

reference gas with a certified value greater than your highest expected hourly concentration, or greater 

than 75% of the highest measured hourly concentration.” 

The commenter states that in view of the two corrective action options provided under the new option 

in (2)(ii), the commenter supports the more restrictive ±10% acceptance criterion relative to the 

acceptance criterion of ±20% in (2)(iii). The commenter includes the passage from the regulatory text, 

which is: 

“If the value measured by the Hg CEMS during the above span linearity challenge exceeds 10 percent of 

the certified value of the reference gas, the monitoring system must be evaluated and repaired and a 

new “above span linearity” challenge met before returning the Hg CEMS to service, or data above span 

from the Hg CEMS must be quality assured using the procedure established in (k)(2)(iii).” 

The commenter states that they interpret the last phrase to allow the Hg CEMS operator to directly 

apply the ±20% acceptance criterion of (2)(iii) to the above span linearity check which surpassed the 10% 

acceptance criterion of (2)(ii), and normalize any above span data according to Equation 22, if the 20% 

criterion is exceeded. No other corrective action would be required. Alternatively if the attempted 

above span linearity check was performed during mill on operations, the commenter believes that the 

Hg CEMS operator could, within the time window for option provided by (2)(iii) (i.e., 24-hours before or 
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after above span condition), perform a new above span check according to the requirements of (2)(iii), 

and normalize the above span monitoring data according to Equation 22 if the 20% criterion is 

exceeded. The commenter believes that neither of these allowed approaches would result in any invalid 

data and neither of these approaches would affect the validity of data below the span value. The 

commenter further states that If these interpretations are not clear enough in the rule, these particular 

action alternatives under (2)(ii) should be made explicit in the rule. 

The commenter further states that an explicit exemption from the requirements in the general 

provisions 63.8(c)(6), PS12A and Appendix F, Procedure 5 to perform the normal daily upscale 

calibration checks (typically at 80-100% of the span value) should be provided (a) during periods when 

emission concentrations significantly exceed the span value, or (b) during periods when Hg0 generator is 

operating at the elevated concentrations necessary for (2)(i)-(iii) requirements, or (c) during periods 

when the generator is in the process of re-equilibration to operate at the normal calibration levels, or (d) 

during rapidly changing effluent concentrations associated with changing mill operating status. The 

commenter includes their rationale for this statement by stating that performing low level calibration 

checks during these periods is not possible during generator equilibration, and even when the generator 

is available, will not provide reliable results during elevated or rapidly changing Hg concentrations. The 

commenter believes that insisting that the calibration check be done will result in inappropriate 

adjustments to the Hg CEMS, only to be undone by the following calibration check after stable 

conditions are achieved, and the commenter further states that such inappropriate adjustments detract 

from data quality, waste valuable technical effort, create frustration, and complicate recordkeeping and 

reporting. The commenter then includes suggested language to be inserted as a new paragraph in 

(k)(2)(iv). 

The commenter adds that cement kiln operators that have chosen to install Hg CEMS should be given a 

time extension for implementing Hg monitoring in the event that NIST fails to accurately certify high 

level Vendor Prime Hg Calibration Gas Generators in sufficient time for vendors to certify their 

respective User Generators. The commenter asserts that the following facts have occurred: 

“There have been some problems with Vendor Prime generators certifications by NIST requiring the 

candidate generators to be returned to NIST for recertification and causing delays of several months. 

No Tekran high-level 3310 Hg0 Generators have been certified by NIST as Vendor Prime Generators. 

Thermo expected NIST certification of its high-level 81iH Generator as a Vendor Prime in August of 2014 

and received it in November. However, there appear to be significant discrepancies between the 

setpoint values and the NIST certified concentrations. The generator is being returned to NIST for 

reevaluation. 

Some weeks will be required for generators installed at cement kilns to be shipped to the respective 

manufacturers, certified relative to the Vendor Prime generators, shipped back to the cement plant, and 

installed in the Hg CEMS.” 

The commenter further states that cement kiln operators cannot be held responsible for delays beyond 

their control that occur at NIST or problems which prevent the Hg CEMS manufacturers from complying 

with the certification of user generators in accordance with the 2009 Interim Traceability Protocol. 
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RESPONSE: The EPA thanks the commenter for their support of our modification to the span value. 

The EPA agrees with the comment that wording changes to (2)(iii) and (l)(1)(ii)(C) were unclear and has 

taken steps to clarify that language in the rule. The use of the word “target” implies flexibility which was 

our intent. The word “expected” is meant to include above span calibrations that were done before 

hand, and we have clarified that in the rule text. 

The EPA agrees with commenter’s interpretation of (2)(ii) in that we did intend to allow the Hg CEMS 

operator to note a CEMS whose linearity check surpassed the 10% level, to switch to a 20% criteria by 

referencing (2)(iii) and proceeding down that path. We intend that a CEMS that does meet the 10% 

level under (2)(ii) would continue to follow the (2)(ii) pathway. We will extend this to include (l)(1)(ii)(B) 

and (l)(1)(ii)(C) HCl monitoring language. We have clarified the language in the final version to reflect 

this intent. 

The EPA agrees that the user of the option for above span validation provided in (2)(ii) and (l)(1)(ii)(B) 

will result in instances of Hg concentrations greater than the expected one-hour average and will result 

in increased data availability concerns. This is the primary reason why this option is a weekly check and 

not a daily check. Where such checks result in unacceptable monitor availability for a facility they may 

wish to choose a different option for above span value validation. 

The EPA agrees with the addition of “...or greater than 75% of the highest measured hourly 

concentration.” to the procedure description in (2)(ii) and (l)(1)(ii)(B) and has modified the rule text to 

reflect this change. 

Relative to the comment that adjusting monitors based on low level calibration checks done during 

milloff periods that might otherwise not require adjustments if conducted during mill-on periods, should 

be exempted from the requirements in the general provisions 63.8(c)(6): we agree with the commenter 

that this otherwise required adjustment is not needed and may create unnecessary corrective actions 

that are not generally helpful or serve to improve monitoring accuracy. We are modifying the rule 

language to reflect this change and provide the exception. 

The EPA disagrees with the commenter’s’ suggestion of excluding such periods from a daily calibration 

check in that we find sound value in requiring a daily upscale calibration check and, where done during 

mill-off conditions we will modify the rule language to reflect that we expect to see a higher upscale 

value during these periods, but without monitor adjustment as may be required through the more 

standard mill-on lower-level daily calibration. We are modifying the rule language to reflect this change.

With respect to the issue of data substitution in (l)(1)(ii)(C), the EPA agrees with the reasons stated by 

the commenter and has removed the requirement for missing data substitution.

Regarding the issue of a delay in the NIST primary standards, the EPA recognizes NIST traceability audit 

and calibration gases as one of the key components of compliance emissions monitoring, and so we 

recognize the concern industry is voicing over availability of high level calibration standards that are 

NIST traceable. The EPA is aware that NIST is currently recertifying their Primary Calibration Standards 

and has plans to move toward providing Primary Standards to Vendors such that Vendors can provide 
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NIST traceable high-level gas generators to facilities in time to meet compliance with the rule. Where 

timing is a concern with respect to the effective compliance date of this rule and availability of a NIST 

Traceable high-level calibration gas generator and/or high level NIST traceable calibration gas cylinders, 

a facility may choose to apply for an alternative test method, under the provisions allowed in 63.7 (f), 

whereby they could operate their CEMS and report the values they measure based on their current 

calibration gas generator and using the highest concentration gas available for the ‘above span’ 

calibrations, retaining all rule required monitoring records as well as a letter from their CEMS vendor 

stating that a high level calibration gas generator was unavailable during such time. Facilities must have 

obtained a NIST traceable form of high-level calibration gas and certify their CEMS by the compliance 

date of the rule. Facilities who are concerned that this is not a workable approach for their monitoring 

needs may also choose to apply for an extension of one year for their Hg limit compliance 

demonstration under the General Provisions Section 63.6(i)(4(i)(A). 

11. HCL CEMS requirements 

Commenter 0861 has various concerns about the proposed revisions to the HCl CEMS requirements and 

has delineated each of these concerns in their comment letter and summarized here (see docket 

EPAHQ-OAR-2011-0817-0861). In addition, the commenter has included an Attachment A to the 

comment letter to provide background on the issues they have raised. 

The commenter voiced strong support for EPA’s proposed change to the HCl CEMS span value to 10 

ppm, but suggests that EPA reinsert deleted language that may provide flexibility and avoid complexity 

of above span calibrations for kilns systems without in-line raw mills which have occasional periods of 

emissions exceeding 10 ppm. The commenter provides suggested revisions to what was proposed, in 

the following submittal: 

“(l)(1)(i) You must use a measurement span value for any HCl CEMS of 0-10 ppmvw, or higher value that 

represents the upper limit of HCl concentrations that occur during normal in-line raw “mill on” 

operation.”

The commenter states that EPA has proposed to revise 40 CFR 63.1350(l)(1)(ii) to provide a new third 

option for dealing with above the span value HCl CEMS data. The (A) option is unchanged and the (C) 

option has minor word changes relative to the promulgated requirements. The (B) option is new. The 

commenter believes that these options are almost identical to the same options as provided for Hg 

CEMS. The commenter believes that the option provided in (l)(1)(ii)(A) of setting a second span to 

encompass mill off HCl concentrations and performing all QA activities required by PS18 and Procedure 

6 (except mill off RATA) is impractical and would potentially result in unacceptable monitor availability, 

and states that with the similar option for Hg CEMS, this doubles the amount of QA checks, doubles the 

amount of QA activities detracting from monitor availability, and doubles chances to exceed a 

specification and render the HCl CEMS non-certified and/or “out-of-control” further decreasing monitor 

availability. The commenter further states that achieving acceptable levels of HCl CEMS availability is 

expected to be challenging for cement kiln operators, especially those using extractive HCl CEMS which 

require very long periods of calibration gas injection to achieve stable responses and additional time to 

recover, especially after high level HCl gas injections. The commenter believes that doubling the QA 

activities is not a viable option. 
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The commenter states that there is a typographical error in (l)(1)(ii)(A): “μg/m3” should be replaced by 

“ppm” in the following sentence. 

“This second span may be rounded to a multiple of 5 μg/m3ppm of total HCl.” 

The commenter also states that there are several text changes in the option provided in (l)(1)(ii)(C) 

needed to align the language with the very similar requirements in the parallel Hg CEMS option (2)(iii) to 

provide consistency and avoid unnecessary complex programming, and the commenter states that they 

have previously requested that EPA make these changes. 

The commenter further states that the word “consecutive” needs to be added to the second sentence of 

(C) option in order to enable the complex programming for this option already developed for Hg to be 

used for HCl CEMS. Failing to make this change renders a successful automated approach unlikely, 

according to the commenter. 

The commenter also states that the same flexibility for the above span target concentration target 

should be provided for HCl CEMS as for Hg CEMS by changing “100 percent” to “150 percent” in the 

following sentence of Option C: 

“The ‘above span’ reference gas must meet the requirements of the applicable performance 

specification and be of a concentration level between 50 and 100 150 percent of the highest 

hourly concentration measured during the period of measurements above span, and must be 

introduced at the probe.” 

The commenter believes that the same minor text changes proposed for §63.1350 (k)(2)(iii) should be 

made to (l)(1)(ii)(c) and included the suggested change: 

“The ‘above span’ reference gas must meet the requirements of the applicable performance 

specification and target a concentration level between 50 and 100 percent of the highest 

expected hourly concentration measured during the period of measurements above span, and 

must be introduced at the probe.” 

The commenter also states that the missing data substitution requirement in (l)(1)(ii)(C) should be 

removed because it is inconsistent with the procedures specified for the other two HCl options for 

quality assurance of “above span” HCl data. Furthermore, the commenter believes that the missing data 

substitution requirements are not included in any Part 60 or Part 63 regulations, and that the last 

sentence in this section (shown below) should be deleted: 

“If the ‘above span’ calibration is conducted during the period when measured emissions are 

above span and there is a failure to collect the required minimum number of data points in an 

hour due to the calibration duration, then you must determine the emissions average for that 

missed hour as the average of hourly averages for the hour preceding the missed hour and the 

hour following the missed hour.” 
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The commenter believes that the option provided in (l)(1)(ii)(C) and (D) should be retained without 

substantial changes to achieve consistency with the Hg above span requirements. Also, the commenter 

states that on the proposed revision to 40 CFR 63.1350(l)(1)(ii), the option provided in (l)(1)(ii)(A) is 

impractical and would potentially result in unacceptable monitor availability. In addition, the 

commenter believes several text changes are needed in (l)(1)(ii)(C) to align the language with the very 

similar Hg CEMS option ((2)(iii)) to provide consistency. The commenter offers suggested language. 

Finally, the commenter has stated support for the new option provided in (l)(1)(ii)(B) to perform a single 

high level “linearity” check weekly, but offers modifications to the language to allow the use of certified 

reference gases with concentrations less than “greater than your highest expected concentration” to 

provide flexibility and a more representative calibration check level. The commenter includes a 

suggested addition to the regulatory language as underlined below: 

“Conduct a weekly “above span linearity” calibration challenge of the monitoring system using a 

reference gas with a certified value greater than your highest expected hourly concentration, or 

greater than 75% of the highest measured hourly concentration.” 

The commenter also states that in view of the two corrective action options provided in (l)(1)(ii)(B), the 

commenter supports the more restrictive ±10% acceptance criterion relative to the acceptance criterion 

of ±20% in (l)(1)(ii)(C). The commenter includes proposed language that states: 

“If the value measured by the HCl CEMS during the above span linearity challenge exceeds 10 

percent of the certified value of the reference gas, the monitoring system must be evaluated 

and repaired and a new “above span linearity” challenge met before returning the HCl CEMS to 

service, or data above span from the HCl CEMS must be quality assured using the procedure 

established in (I)(1)(C).” 

The commenter states that they interpret the last phrase to allow the HCl CEMS operator to directly 

apply the ±20% acceptance criterion of (C) to the above span linearity check which surpassed the 10% 

acceptance criterion of (B), and normalize any above span data according to Equation 23, if the 20% 

criterion is exceeded. The commenter believes that no other corrective action would be required, and 

alternatively if the attempted above span linearity check was performed during mill on operations, the 

HCl CEMS operator could wait until within the window for option provided by (C) (i.e., 24-hours before 

or after above span condition) to perform a new above span check according to the requirements of (C), 

and normalize the above span monitoring data according to Equation 23 if the 20% criterion is 

exceeded. The commenter believes that neither of these allowed approaches would result in any invalid 

data, neither of these approaches would affect the validity of data below the span value, and further 

states that if need be, these particular action alternatives should be made explicit in the rule. 

The commenter states that an explicit exemption from the requirements in the general provisions 

63.8(c)(6), and the proposed PS18 and proposed Appendix F, Procedure 6 to perform the normal daily 

upscale calibration checks (typically at 80-100% of the span value) should be provided (a) during periods 

when emission concentrations significantly exceed the span value, or (b) during rapidly changing 

effluent concentrations associated with changing mill operating status. The commenter further states 

that performing low level calibration checks during these periods will not provide reliable results during 

elevated or rapidly changing HCl concentrations. Insisting that the calibration check be done will result in 

inappropriate adjustments to the HCl CEMS only to be undone by the following calibration check after 
12

stable conditions are achieved. The commenter believes that such inappropriate adjustments detract 

from data quality, waste valuable technical effort, create frustration, and complicate recordkeeping and 

reporting. 

The commenter offers suggested language as follows, be inserted as a new paragraph 

(l)(1)(ii)(E): 

“(E) Routine daily upscale calibration checks required by Appendix F, Procedure 5 and 63.8(c)(6) 

that are performed at levels below the span value, are not required on days when above span 

calibration checks are performed. Routine daily upscale calibration checks during periods when 

HCl concentrations exceed the span value or are rapidly changing may provide unreliable results 

and may be postponed or repeated within 4 hours after HCl concentrations return to below 

span levels. “ 

RESPONSE: The EPA thanks the commenter for their support of our modification to the span value. 

The EPA agrees with the reasons stated by the commenter that a kiln operating without an inline raw 

mill may need a measurement span that exceeds 10 ppmv, as necessary to quantify all expected 

emissions, and we are modifying the rule to reflect this. 

The EPA generally disagrees with the commenter’s concerns about option (l)(1)(ii)(A) for validating CEMS 

data above span. These optional procedures were added to the language as an additional option that 

allows for increased flexibility in handling such data and is clearly optional; meaning that if it isn’t 

workable for a facility they may choose a different validation approach. We have found that some 

facilities may find this option useful, depending on their instrumentation and configuration. 

The EPA agrees with changing “ug” to “ppm” since this is a typographical error, and has modified the 

rule language accordingly. 

The EPA agrees with the comment that wording changes to (2)(iii) and (l)(1)(ii)(C) were unclear and have 

taken steps to clarify that language in the rule. The use of the word “target” implies flexibility which was 

our intent. The word “expected” is meant to include above span calibrations that were done before 

hand, and we have clarified that in the rule text. 

The EPA agrees with the reasons provided by the commenter and we will add the word “consecutive” to 

the second sentence of (l)(1)(ii)(C) to align it with Hg monitoring section (2)(iii). 

The EPA agrees with the commenter’s interpretation of (l)(1)(ii)(B) in that we did intend to allow the HCl 

CEMS operator to note a CEMS whose linearity check surpassed the 10% level to switch to a 20% criteria 

by referencing (ii)(C) and proceeding down that path. We intend that a CEMS that does meet the 10% 

level under (ii)(B) would continue to follow the (ii)(B) pathway. We have clarified the language in the 

final version to reflect this intent. 

The EPA agrees with the commenter’s request to align language of Hg section (2)(iii) and HCl monitoring 

section (ii)(C), for sake of consistency. We will align these two in the final rule, including the upscale 

certification value range, as suggested by the commenter. 
13

The EPA agrees with the reason provided by the commenter and will modify (ii)(B) to specify the use of a 

“reference gas with a certified value greater than your highest expected hourly concentration, or greater 

than 75% of the highest measured hourly concentration.” 

The EPA agrees that the user of the option for above span validation provided in (l)(1)(ii)(B) may result in 

instances of HCl concentrations greater than the expected one-hour average and might result in 

increased data availability concerns. This is the primary reason why this option is a weekly check and 

not a daily check. Where such checks result in unacceptable monitor availability for a facility they may 

wish to choose a different option for above span validation. 

The EPA agrees with commenter’s interpretation of (ii)(B) in that we did intend to allow the Hg CEMS 

operator to note a CEMS whose linearity check surpassed the 10% level to switch to a 20% criteria by 

referencing (ii)(C) and proceeding down that path. We intend that a CEMS that does meet the 10% level 

under (ii)(B) would continue to follow the (ii)(B) pathway. We have clarified the language in the final 

version to reflect this intent. 

The EPA agrees with the commenter’s statement that adjusting monitors based on low level calibration 

checks done during mill-off periods that might otherwise not require adjustments if conducted during 

mill-on periods, should be exempted from the requirements in the general provisions 63.8(c)(6): we 

agree with the commenter that this otherwise required adjustment is not needed and may create 

unnecessary corrective actions that are not generally helpful or serve to improve monitoring accuracy. 

We are modifying the rule language to reflect this change and provide the exception. This issue also 

applies to the Hg calibration check procedures and is discussed in comment response number 10 above. 

The EPA disagrees with the commenter’s’ suggestion of excluding such periods from a daily calibration 

check in that we find sound value in requiring a daily upscale calibration check and, where done during 

mill-off conditions, we will modify the rule language to reflect that we expect to see a higher upscale 

value during these periods, but without monitor adjustment as may be required through the more 

standard mill-on lower-level daily calibration. We are modifying the rule language to reflect this change. 

And with respect to the issue of data substitution in (l)(1)(ii)(C), the EPA agrees with the reasons 

provided by the commenter and has removed the requirement for missing data substitution. 

After the close of the comment period, EPA also was made aware of a delay in vendorprovided HCl calibration gases. This delay, coupled with the delay in the promulgation of the 

PS-18, could result in the inability of sources to meet the September 9, 2015 compliance 

date. As was suggested earlier in Section 10 of this Response to Comment document relative to 

delays experienced in acquiring NIST primary standards for Hg , we advised that sources could 

apply for an extension of one year for their HCl limit compliance demonstration under the General 

Provisions Section 63.6(i)(4(i)(A). 

12. Typographical error in (l)(1)(ii)(A) 
14

Commenter 0861 states that the term “ug/m3” should be replaced with “ppm” in the sentence, “This 

second span may be rounded as a multiple of 5 ug/m3 ppm of total HCl”. 

RESPONSE: The EPA agrees that this was a typographical error, and has made this change in the rule 

language. 

13. Interim compliance method for HCl compliance demonstration. 

Commenter 0861 stated that since the performance specification 18 (PS 18) is not yet finalized, sources 

should be allowed to use an alternative of certification with PS 15, and further that sources should be 

given an 18 month extension after PS 18 is promulgated, to demonstrate compliance using PS 18. This 

extension is requested so that the source can buy CEMS consistent with the PS 18 and perform the 

necessary installation and performance assessment of the CEMS. 

RESPONSE: In the final rule (see eCFR 63.1350(l)), a source is required to either monitor HCl emissions 

continuously using an emissions monitor certified with PS 15, or upon promulgation in accordance with 

any other performance specification. This language allows the source to either continue monitoring 

using PS-15 as the CEMS certification platform, or switch to PS -18, currently scheduled to be 

promulgated in the spring of 2015. PS-18 allows the source more flexibility in their choice of 

technologies used to comply with these monitoring requirements. We want to allow sources the 

opportunity to use PS-18, even though the final version is not promulgated. Though we believe that the 

final version of PS-18 will be published prior to September 9, 2015, sources may require additional time 

to review the final specifications and purchase equipment. Facilities who are concerned that switching 

from PS-15 to PS-18 when PS-18 is available is not feasible, may also choose to apply for an extension of 

one year for their HCl limit compliance demonstration under the General Provisions Section 

63.6(i)(4(i)(A). 

14. Various typographical errors and clarifications 

Commenter 0864 identified several typographical errors, needed clarifications, and misplaced equation 

terms that were located in both the February 12 2013 (see 78FR10036) and this proposed rule, related 

to the following sections: 

40 CFR 63.1343(b)(2) 

(40 CFR 63.1349(b)(1)(vi) 

40 CFR 63.1349(b)(1) 

40 CFR 63.1349(b)(4)(iii) and (6)(iv) 

40 CFR 63.1349(b) 

40 CFR 63.1343(b)(2) 

40 CFR 63.1349(b)(1(vi) 

40 CFR 63.1349(b)(1) 

40 CFR 63.1349(b)(1) Table 1 
15

40 CFR 63.1347(a)(1) 

40 CFR 63.1348(b)(1)(iii)(A)(4) 

40 CFR 63.1349(b)(1)(ix) (needs a cross reference for clarity) 

40 CFR 63.1349(b)(4)(iii), (b)(1)(vi), and (6)(iv) (incorrect terms in denominator) 

40 CFR 63.1349(b), (b)(7)(ii), (b)(3)(iv), (b)(7(iii)(B), (v), (b)(7)(vii) and (ix), (b)(8)(viii) 

40 CFR 63.1350(a)(2), (i)(2), (i)(1), (k)(2)(iii), (k)(5)(iv), (n), and (n)(4) 

40 CFR 63.1354(b)(9) 

RESPONSE: The EPA agrees that these are typographical errors, and in the case of 40 CFR 

63.1349(b)(1)(ix), 40 CFR 63.1349(d)(1)(ii) and 40 CFR 63.1354(b)(9)(ix) agrees that a cross reference and 

more consistent language would make these sections more clear, and thus has corrected or revised 

these in the final rule. 

15. Monitoring during startup and shutdown (SS) periods 

Commenter 0861 supports the proposed edit to remove the obligation to collect and average 

monitoring data during SS, since accurate monitoring data could not be compiled during SS events 

according to the recent amendments

RESPONSE: The EPA appreciates the support for this proposed change. 

16. THC compliance test interval of 30 months 

The commenter supports the amendment to the testing interval for coal mill stacks and alkali bypasses 

adopting an interval of 30 months. 

RESPONSE: The EPA appreciates the support for this proposed change. 

17. Exclusion of data generated during malfunctions (40 CFR 63.1348(b)(1)(iii) 

Commenter 0861 requested clarification on the term “operating level” whereas did the EPA mean to 

reference the data used to determine if an operating limit is being met, and also requested clarification 

relative to should the data for any given hour be excluded if any of the underlying monitoring devices 

malfunction? For example, if the mercury CEMS malfunctions, but the production level monitor operates 

properly, is it correct to exclude both the CEMS data for the hour(s) of malfunction and the associated 

production data for the same hours? Conversely, if the production monitor fails, but the mercury CEMS 

is still operating, is the commenter correct to assume that both the CEMS and production data during 

the production monitoring malfunction are excluded? 

RESPONSE: The operating level is the levels of parametric monitoring at the time of the malfunction. 

You may not use the emissions occurring at the time of the malfunction and also the operating levels of 

the time of malfunction.

The malfunction discussed in 63.1348(b)(1)(iii) is the malfunction of the source operations or 

control device operability and not the malfunction of the monitoring devices themselves. No exclusion 

is intended of any data associated with malfunctions of production monitors, or malfunctions of CEMS. 
16

The source is still responsible for reporting collected data from unaffected monitors, including measured 

emissions, during CEMS or process monitoring malfunctions, since the actual equipment (i.e. kiln) is still 

operating.

18. Acceptance of Performance Specification 8 or 8a 

Commenter 0861 supports the addition of PS 8 as an acceptable standard for a THC monitor. 

RESPONSE: The EPA appreciates the support for this proposed change. 

19. Out of date regulation under 40 CFR 63.1355(d) 

Commenter 0861 stated that the rule contains an out of date requirement to keep annual records of the 

amount of cement kiln dust (CKD) removed from the system. This requirement is no longer valid since 

the new rule utilizes mercury controls and compliance demonstrations for meeting the new mercury 

limit, and thus the CKD records are not relevant. 

RESPONSE: The EPA agrees that 40 CFR 63.1355(d) is no longer relevant since the final rule utilizes 

mercury controls and the CKD records are not needed when compliance entails the procedures required 

in 63.1350, and thus is removing this requirement from the final rule. 

20. Mercury Testing Frequency (40 CFR 63.1350(k)(5)(iv) 

Commenter 0861 supports the EPA’s proposed clarification of the mercury emissions testing frequency 

for alkali bypasses to be the same for coal mills, and that the frequency is reduced if the result is below 

the method detection limit. The commenter states that EPA should clarify that when the stack 

concentration is below the MDL, the emissions from the stack should be reported as zero. 

RESPONSE: All values below the MDL should be reported at the MDL level, and not reported as zero. 

Through the upper prediction limit (UPL) process, the MDL was considered when the limit was 

developed, and including MDL values in reported emissions will therefore not create a compliance 

concern. Sources using Method 30B for mercury emissions measurements have access to lower MDL 

values than sources who choose to demonstrate compliance with Method 29. 

21. Flow monitoring requirement (40 CFR 63.1350(n)) 

Commenter 0861 supports proposed language which clarifies that flow monitoring is only required when 

using a CEMS. 

RESPONSE: The EPA appreciates the support for this proposed change. 

22. Limits for raw material dryers 

Commenter 0861 states that limits for materials dryers (40 CFR 63.1343(b)(1) and 40 CFR 63.1346) 

THC/OHAP emission limits for material dryers during operation, and work practices per 63.1346(g) 

during start-up and shutdown could be applied when an in-line raw mill with an external heat source is 

operated as a material dryer independently from the kilns, and thus could utilize the kiln stack THC 

CEMS. The commenter requests that EPA provide specific guidance regarding rule applicability for this 

situation, and whether this infrequent operation should be considered negligible. 
17

RESPONSE: The commenter describes a unique situation whereby the source is utilizing an inline raw 

mill that is not receiving kiln exhaust, but rather is heated by an external heat source. In this situation, 

the raw mill would then be considered a raw material dryer, with THC limits as shown in 63.1343(b)(1) 

and 63.1346. 

23. Clarification needed on Note to Paragraph (a) for Section 63.1348 

Several commenters through telephone communications (as recorded in the final docket) have 

requested clarification on the Note for Paragraph (a) of Section 63.1348 relative to whether you must 

complete the performance test prior to or on the compliance date. Also the commenters seek 

clarification on the actual compliance date, since the general provisions under 63. 7 allows 180 days 

after the compliance date to show compliance. 

RESPONSE: The source must perform and report Relative Accuracy Test Audits (RATA) for the CPMS or 

CEMS within 180 days after the compliance date, since according to the General Provisions, 40 CFR 63.7, 

the source has 180 days to demonstrate compliance. The Note to paragraph (a) was to provide 

clarification that a source’s 30 day operating day performance test could start the day after the effective 

date, so that the rolling averages would begin to be developed following the first monitoring day after 

the compliance date. It is expected that existing sources have procured their monitoring equipment and 

done their RATA for each emission source and is confident that they are in compliance on the 

compliance date, or within the time alloted per the General Provisions 40 CFR 63.7, including sufficient 

time, post RATA, to demonstrate compliance with a 30 day rolling average emission limit. 

24. Dioxin Testing Temperature Limit During Startup/Shutdown 

One commenter as listed in the docket, requested clarification that the temperature limit as listed in 

Section 63.1343(a), footnote (2), still applies during startup/shutdown situations. 

RESPONSE: The temperature shown in footnote (2) to Table 1 under Section 63.1343(a) is a decision 

point and ultimately a parametric limit measured during the performance test, whereby if the average 

temperature at the first PM control device inlet during the performance test is 400 degrees F or less, the 

limit is 0.40 ng/dscm (TEQ), but if it is greater than 400 degrees F, the limit is 0.20 ng/dscm (TEQ). The 

source must then comply with the limit recorded during that performance test. Once the limits are set 

during the dioxin compliance test, they apply at all times, and thus, to assure compliance, the 

temperature operating limit is to be continually monitored during startup and shutdown. 

25. Clarification that startup and shutdown is part of Section 63.1348(b)(1)(iii) 

One commenter as listed in the docket, requested clarification on this section that requires a source to 

not use data recorded during monitoring system malfunctions or repairs associated with monitoring 

system malfunctions in calculations used to report emissions or operating levels, and whether this 

applies to startup and shutdown events. 
18

RESPONSE: This section was intended for both startup and shutdown as well as malfunction events, and 

thus the term “startup and shutdown” has been added to this section in the final rule. 

26. Clinker coolers and the PM CPMS procedure

One commenter, through a communication via telephone (and placed in the final docket) asked 

clarification as to whether a clinker cooler, which is subject to a PM limit for new and existing sources 

under Section 63.1343(b), is required to employ the PM CPMS procedures for measuring PM emissions. 

RESPONSE: A source with a clinker cooler is required to employ the PM CPMS performance testing 

requirements and compliance monitoring procedures, but this requirement was inadvertently omitted 

from both the final rule and the proposed rule amendments. Thus, the final rule has been corrected at 

63.1349(b)(1). 

Subpart F (New Source Performance Standard for Cement Kilns) 

27. Rolling Average Definition 

Commenter 0861 stated that the rolling average definition is not clear. 

RESPONSE: EPA agrees with the commenter and has revised this definition to be the same as the 

revised definition under 63.1341. 

28. Opacity Limits for Clinker Coolers

Commenter 0861 stated that opacity monitoring should be dropped for any clinker cooler that has a PM 

CPMS, since the PM CPMS is better suited for monitoring the PM. The commenter further states that 

the opacity provision was dropped under section 40CFR 60.62(a)(2) for this same reason. 

RESPONSE: The EPA agrees with the commenter for the reasons stated and has removed this provision 

from the final rule. 

29. Compliance date for revised monitoring and recordkeeping (40 CFR 60.62(e)) 

Commenter 0861 states that in the revised rule, EPA is clarifying that all of the new monitoring and 

recordkeeping provisions in the NSPS will apply to units triggering NSPS before 2008, and that they will 

apply on the effective date of the NESHAP through a cross reference to 40 CFR 63.1351(c). The 

commenter interprets that in doing this, EPA is indicating that units triggering NSPS before the latest 

changes are now subject to the newer monitoring and recordkeeping. The commenter states that this is 

not appropriate, and that the new provisions should only apply to kilns subject to the new emissions 

limits. The commenter further states that kilns subject to the old NSPS limits should remain subject to 

all of the previous requirements, including those for monitoring and recordkeeping that existed at the 

time NSPS became an applicable requirement. The commenter believes that it is not appropriate to 

change the applicable NSPS requirements at a later date, and the commenter asks that the prior 

monitoring and recordkeeping provisions be reinstated and made applicable to the kilns that triggered 

NSPS under the old limits. The commenter also stated that if EPA does not make this correction, the new 

provisions should not apply until the 2015 NESHAP compliance date. 
19

RESPONSE: The EPA disagrees with the appropriateness of revising monitoring and recordkeeping as 

outlined by the commenter. Though it may not be appropriate to apply new emissions limits to kilns 

built before 2008 due to those kilns being designed to meet only the limits at the time, it is appropriate 

to apply monitoring and recordkeeping requirements to NSPS kilns prior to 2008. These requirements 

are independent of the emission limits: they do not affect the kiln design. In addition, EPA applied 

revised monitoring and recordkeeping requirements in the 1988 NSPS review and thus had set a 

precedent for this practice. Also note there is no cost involved because NSPS sources have to meet the 

revised NESHAP monitoring and recordkeeping requirements, and thus there is no additional burden. 

The EPA also disagrees with allowing the new provisions to not apply to NSPS sources that 

commence construction after June 16, 2008 until the 2015 NESHAP compliance date (September 9, 

2015), since monitoring and recordkeeping requirements are in effect for NSPS sources at the date of 

final promulgation, which in this case was November 8, 2010. 

30. Various technical clarifications and typographical corrections

Commenter 0861 noted the following technical clarifications and typographical corrections needed: 

40 CFR 60.63(c) (Addition of the term “digital signal” is needed, as it was in other sections) 

40 CFR 60.63(c)(1) (Cross references for clinker cooler limit should be added) 

40 CFR 60.63(c)(7) (The term high load capacity removed in some sections and not others). 

RESPONSE: The EPA agrees that these are typographical errors, and thus they will be revised in the final 

rule.