## St andards of Perform ance for Portland Cement Plants (40 CFR 60 Subpart F )

Response to Public Comments

US Environmental Protection EPA Office of Air Quality Planning and Standards Sector Policies and Programs Division Metals and Minerals Group Research Triangle Park, NC 27711

August 6 , 2010i 

## Ta ble of Contents 1. Introduction

................................ ................................ ................................ .......................... 1 2 Legal Issues Related to EPA’s Interpretation of the CAA

................................ .................. 4 2.1 Best Demonstrated Technology

................................ ................................ .............. 4 2.2. Greenhouse Gases

................................ ................................ ................................ ... 4 2.3 Emission Limits

................................ ................................ ................................ ...... 6 2.4 Pollutants not Included (VOC, PM 2.5 )

................................ ................................ .... 9 2.5 General

................................ ................................ ................................ .................. 10 3 Applicability

................................ ................................ ................................ ...................... 12 3.1 Modified Kilns

................................ ................................ ................................ ...... 12 4 Emission Limits

................................ ................................ ................................ ................. 16 4.1 General

................................ ................................ ................................ .................. 16 4.2 Format

................................ ................................ ................................ ................... 16 4.3 NO x ................................ ................................ ................................ ....................... 16 4.4 SO 2 ................................ ................................ ................................ ........................ 24 4.5 PM

................................ ................................ ................................ ......................... 30 4.6 Opacity ................................ ................................ ................................ .................. 35 4. 7 VOC and CO

................................ ................................ ................................ ......... 36 4.9 Fugitives

................................ ................................ ................................ ................ 37 4.10 Overall Achievability

................................ ................................ ............................ 37 5 Monitoring and Recordkeeping

................................ ................................ ......................... 39 5.1 SO 2 ................................ ................................ ................................ ........................ 39 5.2 PM

................................ ................................ ................................ ......................... 40 5.3 Opacity ................................ ................................ ................................ .................. 40 5.4 CEMS

................................ ................................ ................................ .................... 41 5.5 Clinker Production

................................ ................................ ................................ 42 6 Test Methods and Procedures

................................ ................................ ............................ 43 7 Impacts

................................ ................................ ................................ ............................... 44 7.1 Cost and Cost Effectiveness

................................ ................................ .................. 44 7.2 Environmental and Energy

................................ ................................ ................... 46 7.3 Economic

................................ ................................ ................................ .............. 48 7.4 Multipollutant

................................ ................................ ................................ ....... 49 8 Miscellaneous

................................ ................................ ................................ .................... 50 8.1 Proposed Rule

................................ ................................ ................................ ....... 50 8.2 Technical Support Document

................................ ................................ ............... 51



## List of Ta bles
Table 1

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

................................ ................................ ................................ ............. 21 

### 1. Introduction O n June 16 , 2008 the U.S. Environmental P rotection Agency (EPA proposed to amend the New Source Performance Standards (NSPS) for portland cement plants in 40 CFR 6 0 subpart F (hereafter referred to in this document as “Subpart F ”) to revise emission limits and compliance requirements for af

fected facilities which commence construction , reconstruction , or modifi cation after June 16 , 2008

. The proposed amendments also include additional testing and monitoring requirements for affected sources. Ini tially , a 60

- day period ending August 15 , 2008, was provided for the public to submit comments to EPA regarding the proposed Subpart F amendments . In response to a request from commenters, the public comment period was extended by

EPA an additional 45 days and ended September 30 , 2008. This document presents a summary

of the public comments that the EP A received on the proposed Subpart F amendments. A total of 23 sets of comments were received by EPA regarding the proposed Subpart F amendments . S ome of the comment sets were signed or submitted on behalf of multiple commenters

. Also, in some cases duplicate comment sets from the same commenter were received

. Table 1

- 1 lists the names of the commenters and their affiliations for each of the comment sets received regarding the proposed Subpart F amendments

. Some commenters also submitted supplemental information and data to support their comments. This document presents a summary

of each substantive comment received by EPA from the commenters listed in Table 1

- 1 . The comment summaries are grouped by topic in Sections 2 through 8 as follows:

 Section 2

–Le gal Issues Related to EPA’s Interpretation of the CAA

 Section 3

–Applicability

 Section 4

–Emission Limits

 Section 5

–Monitoring and Recordkeeping

 Section 6

–Test Methods and Procedures

 Section 7

–Impacts

 Section 8

–M iscellaneous Comments2

Table 1
- 1. List of C ommenters on Amendments to 40 CF R 60 Subpart F Proposed June 16 , 2008 ( 73 FR 34072 )
Docket No. EPA
- HQ
- OAR
- 200 7
- 0 877 Commen ter Name, Affiliation, and Date Received 056 Anonymous Public Comment August 15, 2008 05 7 Kevin Batchelder EnviroLogix, Inc. July 1 0, 2008 059 Al Armendariz, Ph.D. Private Citizen September 17, 2008
060 A. A. Linero, P.E., Program Administrator Bureau of Air Regulation Florida Department of Environmental Protection September 29, 2008
061 M ichael H. Winek Babst, Calland, Clements, and Zomnir On behalf of Armstrong Cement and Supply Corporation September 30, 2008

062 Edmund G. Brown Jr., Attorney General of California Joseph R. Biden, III, Attorney General of Delaware Martha C oakley, Attorne y General of Massachusetts Andrew M. Cuomo, Attorney General of New York Hardy Myers, Attorney General of Oregon William H. Sorrell, Attorney General of Vermont September 30, 2008 063 Carolyn Slaughter, Program Development Manger Institute of Clear Air Co mp anies (ICAC) September 30, 2008 064 Andrew T. O’Hare, Vice President Regulatory Affairs Portland Cement Association (PCA) September 30, 2008

065 Timothy Ballo James Pew Janette Brimmer Earthjustice on behalf of Clean Air Task Force and Downwinders At Risk September 30, 2008 066 Melanie Sattler, Ph.D, P.E. Private Citizen September 30, 2008 067 Shelly Kaderly, Air Quality Division Administrator Nebraska Department of Environmental Quality (NDEQ) September 30, 2008
068 Robert Hodanbosi, Co

- Chair Permitting Committee Ursula Kramer, Co

- Chair Permitting Committee National Association of Clean Air Agencies (NACAA) September 30, 2008
069 J. Jared Snyder, Assistant Commissioner Office of Air Resources, Climate Change, and Energy New York State Department of Environmental Conservation September 30, 20083

Docket No. EPA
- HQ
- OAR
- 200 7
- 0 877 Commen ter Name, Affiliation, and Date Received

070 My ra C. Reece, Chief Bureau of Air Quality South Carolina Department of Health and Environmental Control September 30, 2008
071 Mohsen Nazemi, P.E., Deputy Executive Officer Engineering and Compliance South Coast Air Quality Management District (AQMD) September 30, 2008 072 Downwinders At Risk September 30, 2008

073 Craig S. Campbell, Vice President Environment and Government Affairs Lafarge North America Cement Division September 30, 2008

074 Steven Mi ller, Product Manager Py roprocessing Technology Ove L. Jepsen, Senior Vice President, North America FLSmidth Inc September 29, 2008 075 Spencer Weitman, President National Cement Company of Alabama, Inc. September 30, 2008 076 , 082* Mark S. Terry, Presid ent Polysius Corp, a ThyssenKrupp Technologies Company September 26, 2008 077 Richard T. Cusick, President Humboldt Wedag, Incorporated September 22, 2008

078 Michael Pelan and Craig Campbell Environment and Government Affairs Lafarge North American Ceme nt Division June 30, 2008
079 ** Andrew T. O’Hare, Vice President Regulatory Affairs Portland Cement Association (PCA) June 17, 2008 08 0 Andrew T. O’Hare, Vice President Regulatory Affairs Portland Cement Association (PCA) September 25, 2008 081 Roger Brower, Principal Zephyr Environmental Corporation June 09, 2008
083 Satish Sheth Vice President

– Environmental U.S. Operations Cemex, Incorporated May 05, 2009 * Duplicate copies of same comments entered in docket

. ** Request for extension of public comme nt period.4



### 2 Legal Issues Related to EPA’s Interpretation of the CAA 2.1 Best Demonstrated Technology Comment : One commenter ( 68 ) agrees with EPA ’s approach of basing best demonstrated technology

(BDT) on recently

issued state permit data and best avail able control technology (BACT) determinations developed as part of new source review (NSR) as well as EPA’s assessment that the main difference between BACT and BDT determinations for purposes of NSPS is that a BACT determination is made on a site

- specific basis. Response : In addition to state permit limits and BACT determinations, we also reviewed emissions data to verify

that the emission limits for new sources were reasonable. Comment : Various commenter s ( 59, 68 ) urge EPA to require the portland cement industry to utilize BDT and state that selective cataly tic reduction ( SCR) will provide the greatest nitrogen oxide (NO x) reductions in addition to other benefits

. The c ommenter states that EPA is required to look toward emerging technologies in determining what emissions reductions have been adequatel y demonstrated. Commenter 68 states that under CAA section 111, EPA can determine that a system has been “adequatel y demonstrated” even if the majority of sources are not utilizing it and, citing the D.C. Circuit Court of Appeals with regard to cement plants , “‘[A]dequately

demonstrated’ does not require that any cement plant now in existence be able to meet the proposed standards. Section 111 looks toward what may be fairly projected for the regulated future, rather than the state of the art at present, since it is addressed to standards for new plants...”. According to the commenter, the D. C. Circuit has also held that “...Congress also meant for emerging technologies to be given consideration when EPA promulgate s NSPS.” (see Sierra Club v. Costle )

. As part of its discussion of SCR as BDT, the commenter cites various studies as demonstrating the performance of SCR at coal

- fired power plants and successful application of SCR at a cement plant in Germany ; the co

- ben efits achieved through control of other pollutants ; and cost effectiveness

. Response : See preamble for the response. 

### 2.2 . Greenhouse Gases Comment : One c ommenter ( 64 ) supports EPA’s decision not to exp and the revised NSPS for p ortland cement plants to address emissions of GHGs

. Citing a ruling b y the D.C. Circuit Court , the commenter states that EPA is not obligated to address any particular pollutants when issuing or revising NSPS. The commenter also states that the Supreme Court’s Massachusetts v. EPA dec ision addressed EPA’s regulation of GHG emissions from motor vehicles under CAA section 202(a)(1), but nothing in that decision or any other court decision requires EPA to regulate GHGs through NSPS. Commenter 64 states that there is no reason to believe that standards for GHG emissions in the p ortland c ement NSPS would be an effective or appropriate means of climate change mitigation and that EPA and Congress are currentl y grappling with the best approaches for addressing climate change and those questions are best answered after careful study and public debate, rather than short

- circuited by appl ying NSPS to GHGs

. According to the commenter, it is unlikely that an NSPS standards for GHGs at cement plants would produce5

any meaningful reduction even in GHG emissions from new cement plants: the only known method for controlling carbon dioxide emissions from cement plants is efficient fuel combustion, and cement plant operators already have large financial incentives to minimize fuel usage to the extent practic able. Response : See the Federal Register notice for the final amendments for the response this comment. EPA notes further that the commenter is correct that the Supreme Court’s decision in State of Massachusetts v. EPA does not require EPA to address GHG emissions from cement kilns in this rule. On the other hand, that opinion holds that GHGs are pollutants under the Act, which brings GHGs under the potential authority of section 111 (like any other pollutant). Comment : Several commenters (62, 65, 69) objec ted to EPA not proposing standards for greenhouse gas (GHG) emissions under the proposed NSPS. One commenter (62) criticizes EPA’s decision to not propose any NSPS for GHG emissions from p ortland cement plants. The commenter states that even though the courts have confirmed that GHGs are air pollutants subject to regulation under the CAA, EPA has not issued any such standards, instead issuing an Advance Notice of Proposed Rulemaking (ANPR) that seeks public comment on whether to regulate GHG emissions under the CAA at all

. Commenter 62 protest s this course of action, and request that EPA revise the proposed rule to include NSPS for GHG emissions. According to commenter 62, EPA’s failure to propose NSPS for GHGs in the proposed rule violates § 111 of the CAA (42 U.S.C. §7411) , which requires EPA to determine whether GHG emissions emitted by

cement plants may

endanger public health or welfare, and to promulgate NSPS for each air pollutant emitted by cement plants that contributes significantly to global warming pollution. The commenter states that a s the second largest industrial source of carbon dioxide emissions in the United States (emitting 45.7 million metric tons of carbon dioxide in 2006 ) , the cement industry contributes significantly

to GHG emissions and there can be no serious dispute that GHG emissions endanger public health and/or welfare. The ANPR that EPA issued instead is no substitute for action and does not commit to regulating GHG emissions from any source . C ommenter s 65 and 69 submitted several exhibits in support of their comments. A summary of the comments is presented here. To review the entire comment , please refer to the comment at www.regulations.gov. The c ommenter state s that:

 EPA is required b y §111 to promulgate NSPS for all pollutants emitted by a regulated source category

including CO 2 emission from c ement p lants and EPA’s assertion that § 111 does not compel the agency to regulate CO 2 emissions is contrary to the Act’s plain language.

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

encompasses CO 2 .
 At a minimum, in directing that NSPS be established for sources that cause, or contribute significantl y to air pollution which may reasonably be anticipated to endanger public health and welfare, Congress showed that it meant to require limits on emissions of any6

pollutants that cause or contribute to such endangerment. Because cement plants emit CO 2 in such amounts that those emissions significantly contribute to “air pollution whi ch may reasonably

be anticipated to endanger public health or welfare,” EPA is legall y required to issue standards of performance limiting those emissions. EPA cannot rationally assert that cement plant CO 2 emissions do not meet these criteria, and the agency ’s refusal to promulgate standards of performance is therefore unlawful.

 EPA’s contention that it can refuse to regulate CO 2 emissions on the basis of interactions with other CAA provisions is impossible to reconcile with § 111, because that section cle arl y contemplates that EPA will adopt standards of performance covering pollutants that have not previousl y been subject to regulation under the Act.

 Cement p lants’ emissions of CO 2 cause, or contribute significantly to, air pollution which may reasonably be anticipated to endanger public health or welfare and significantly contribute to global climate change.

 There are existing technologies that can reduce emissions of CO 2 from cement plants. In addition to the suggest ed technologies, other measures that would also have CO 2 reduction benefits include shifting form high carbon content fuels, such as coal, to lower carbon content fossil fuels, such as natural gas.

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

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

- listed endangered species. Response : See preamble for the final amendments for the response to this comment. 

### 2.3 Emission Limits Comment: Several c ommenter s ( 65 and 72) state that EPA’s proposed NSPS for SO 2 emissions are inconsistent with §111 and do not reflect the degree of emission limitation that is achievable through the application of wet scrubbers , which have already been installed on some kilns and are the best adequately

demonstrated technology

. Acc ording to the commenter s 65 and 72 , the propose d SO 2 limit of 1.33 lb/ton of clinker is so lenient that only a f ew kilns will actually

use scrubbers to compl y . EPA acknowledges that far better SO 2 levels can be achieved and are achieved through the use of wet scrubbers. Specifically , EPA admits that some kilns are already subject to a BACT limit of 0 .2 lb/ton of clinker. EPA describes that level as one “where moderate and high sulfur kilns”

— as opposed to only a few kilns with extraordinaril y high uncontro lled SO 2 levels, “will require the use of a wet scrubber for SO 2 control.” Commenter 72 added that EPA’s desire to shelter new kilns from having to appl y add

- on controls is irrelevant under § 111, and EPA’s interpretation of § 111 as allowing it to avoid setting standards reflecting application of the BDT based on that irrelevant policy consideration is unlawful. Response : See preamble for the response.7

Comment: One c ommenter ( 72 ) states that existing application of wet scrubbers in the cement industry means wet scrubbers should be automatically considered BACT for all new U.S. kilns. Section 111(a)(1) defines a “standard of performance” to mean “a standard for emissions of air pollutants which reflects the degree of emission limitation achievable through the application of the best sy stem of emission reduction which (taking into account the cost of achieving such reduction and any nonair quality health and environmental impact and energy requirements) the Administrator determines has been adequatel y demonstrat ed.” (42 U.S.C. § 7411(a)(1) )

. EPA evidently has concluded that wet scrubbers have been adequatel y demonstrated considering cost and the other statutory

factors a s EPA acknowledges, some kilns already have installed them. Further, EPA’s proposed NSPS reflec t the use of wet scrubbers, albeit b y only a few kilns. Given that wet scrubbers are the best adequatel y demonstrated technology, § 111 requires EPA to set NSPS at the level that is “achievable through the application of” wet scrubbers. Response : See the preamble for the response. Comment : One c ommenter ( 65 ) states that , although EPA agrees that it must set NSPS for NO x , the agency

rejects the technology that best reduces NO x , SCR . EPA states that SCR can reduce NO x emissions by

about 80 percent and could be used to attain a standard of 0 .5 lb/ton of clinker. Nonetheless, EPA ultimately proposes to set a much less protective NO x standard of 1.5 lb/ton of clinker, based on the use of either “staged combustion in the calciner (SCC),” SNCR , or both

. EPA offers a variety of reasons for rejecting SCR as the BDT , but none of them have merit. The commenter provides the following comments regarding EPA ’s reasons why SCRs were not chosen as BACT:

 EPA admits that SCR has been used at three kilns in Europe, but states th at the kilns are not preheater/precalciner kilns like new US kilns will be. However, EPA does not say why this distinction makes any difference n or why

future US kilns have to be preheater/precalciner kilns even if preheater kilns may be cleaner. The CAA requires that NSPS reflect application of the best demonstrated sy stem of reduction and to do otherwise to ensure the continued use of a particular production process w ould be unlawful . EPA’s failure to explain why the use of a precalciner precludes the use of SCR is arbitrary . EPA argues that the ideal location for SCR is at a point where dust levels are high enough that they

may clog the SCR device. But a study on the application of SCR to cement plants (which EPA neglects to mention) states that the probl em of catalyst fouling has been solved in Europe. EPA itself has stated that the operational history of SCR installation at a cement plant shows that it is achieving NO x reductions in a reliable manner and has named SCR as an available technology for cement kilns in its Best Available Retrofit Technology (BART) anal ys is. Reports from industry and independent contractors make the same point. EPA’s claims about “potential technical difficulties” are at odds with all of this information.

 According to the comme nter, EPA cites cost effectiveness and the uncertainty of the costs estimates as reasons for rejecting SCR. The commenter states that EPA’s views about cost

- effectiveness are irrelevant and unlawful under §111, which requires standards to reflect the degre e of limitation that is “achievable” through the application of the BDT , not the degree of limitation that “EPA considers cost

- effective.” EPA’s cost

- effectiveness arguments are arbitrary as SCR reduces not only NO x but also volatile organic8

compounds, dio xins and furans, ammonia, and mercury

. If cost effectiveness is relevant, the true cost

- effectiveness of SCR would have to reflect reductions of all these pollutants and

—at a minimum

—VOCs, for which EPA has a statutory obligation to set NSPS. The commenter states that EPA’s consideration of SCR’s cost

- effectiveness only with respect to NO x and not the other pollutants that SCR controls is at odds with the agency ’s stated intent to use a multi

-pollutant and sector

- based approach to setting standards. Finally , EPA’s alleged “uncertainty” about costs do es not justify its rejection of SCR. The uncertainties all relate to technical issues that have been resolved. For EPA to rely on such uncertainty

despite record evidence showing it to be unfounded is arbitrary

. EPA may not reject a s ys tem by

claiming that it has not bothered to full y investigate it, especiall y a s ys tem such as SCR that is already in use and recognized as reliable and effective.

 Finally , EPA attempts to rely on alleged “adverse non

- air and energy implications” to reject SCR. The only

energy concerns EPA cites, however, relate to using SCR in a low dust environment where (EPA claims) the exhaust gas would have to be reheated. As EPA acknowledges , that issue does not exist if the SCR unit is placed u pstream where the exhaust gas is already the ideal temperature and the dust issues associated with such placement have been addressed and solved. The only non - air impact EPA mentions is the disposal of used catal ys ts. Such disposal issues alway s arise from the use of air pollution control issues. EPA does not explain why catal ys t disposal outweighs the air pollution benefits that would result from SCR. Response : See preamble for response

. Comment : Commenter 64 believes that the best approach is for EPA not to amend the NSPS to include NO x limits. If EPA indeed intends for the NSPS NO x limits only to apply to new cement plants or those that have undergone a redesign to use a preheater/precalciner s ys tem, then those NSPS limits will be applied to a new unit or capital project that will require federal and/or state permitting. It may

also be subject to SIP limitations, visibility protection rules, other state requirements, and so forth. The site

- specific considerations that go into such determinations are well

- e stablished and are much better able to address the variety of variables affecting NO x emission limit achievability at cement plants. Relying on other applicable requirements rather than developing revised NSPS for NO x also assures that NO x limits for new and reconstructed plants are based on evolving information and technology , not set in stone until the next rulemaking like NSPS. The commenter states that EPA is not under any obligation to include NO x limits in the revised NSPS. The decision of what pollut ants to regulate, and indeed whether to revise the NSPS at all, is discretionary . Obviously , EPA has never regulated NO x emissions through the NSPS from cement plants in the past, and even now EPA does not include limitations in the NSPS for many fuel

- burning sources, including some ty pes of boilers. In other cases, EPA has recognized that NSPS need not address all concerns and has taken into account that other requirements will apply to new or modified sources under federal and state air pollution laws and regulations, resulting in other or additional control requirements. Response : EPA disagrees that the Agency ’s decision as to whether to establish a NO x limit in this NSPS revision is dictated by the lack of any NO x limits in the existing NSPS. The absenc e of9

NO x limits in the NSPS previously was due to the lack of a demonstrated add

- on control technology

applied to cement kilns during EPA’s last review of the NSPS in 1988. Beginning in the 1990’s, S NCR sy stems have been considered and installed on numerou s cement kilns in the U.S. Furthermore, NO x is emitted in large amounts by cement kilns and may

be controlled cost

effectivel y b y a number of means, including SNCR. EPA is acting well within its discretion, and in keeping with the goals and policies underl ying section 111, in establishing standards for NO x as part of this revision. 

### 2.4 Pollutants not Included (VOC, PM 2.5 

### ) Comment : Several commenters ( 65 and 72 ) stated that i t is well established that PM 2.5 endangers public health and that under §111(a)(1), EPA must set NSPS for PM 2.5 that reflect the degree of emission reduction that is achievable through application of the “best” sy stem of emission control that is adequatel y demonstrated. Because the CAA requires emission standards for PM 2.5 , the agency’s failure to set such standards is unlawful. EPA discusses the amount of PM 2.5 emissions that its total PM standard would reduce but does not claim that fabric filters are the best demonstrated sy stem of control for PM 2.5 . Nor would any

such claim be credibl e , in the commenter’s opinion . Fabric filters do not remove the condensable portion of PM emissions, which is in gaseous form at the stack but condenses into liquid or solid form within a few seconds of leaving the stack. EPA has recognized that condensabl e PM is controlled not by fabric filters but by

wet FGD, wet ESP and alkali injection. EPA states that it “supports reducing condensable PM emissions,” but does not know whether cement kilns are a significant source of condensable PM although they are aware that cement kilns emit enormous amounts of PM. Studies show that the condensable portion of PM emissions from coal

- fired power plants is 50

- 75 percent

. D ata available to EPA show that cement kilns’ condensable PM emissions account for a significant porti on of their total PM emissions. For example, Titan Cement’s North Carolina kiln reports that over 40 percent of its PM emissions are condensable PM. The CALPUFF model for PM speciation indicates that condensable PM makes up 86 percent of the total PM emiss ions from a dry kiln with a fabric filter

— i.e. , from the kilns that will be governed by the NSPS. Response : EPA has insufficient data on condensable PM data to establish limits at this time. EPA notes that under the portion of fine PM that is attributab le to SO 2 emissions will be reduced as a result of wet scrubbers that are installed to comply with the new limits for SO 2 . Also, the increased use of membrane filters to comply with the revised PM standard will reduce PM fine emissions in comparison to standard woven filters. In addition, in EPA’s revised NESHAP, both existing and new kilns are expected to use wet scrubbers in order to comply with the limits for HCl as well as mercury , and in some cases with the revised limits for THC in the cases where the sources use a regenerative thermal oxidizer (RTO) because a wet scrubber must precede the RTO to prevent the fouling of the RTO interior mechanism. Comment : One commenter ( 72 ) states that the fuels and raw materials used in cement clinker production can r esult in the emissions of hydrocarbon pollutants, also known as volatile organic compounds. Volatile organic compound emissions contribute to the production of ground

- level ozone and some VOC’s are highl y toxic. Citing EPA information, the commenter states that c ement plants throughout the country report significant quantities of hydrocarbon HAP10

emissions

. NSPS implement CAA section 111(b) and are issued for categories of sources which EPA has listed because they cause, or contribute significantl y to air po llution which may reasonabl y be anticipated to endanger public health or welfare. The primary purpose of the NSPS is to attain and maintain ambient air quality by ensuring that the best demonstrated emission control technologies are installed as industrial infrastructure is modernized. Response : Under the NESHAP for portland cement manufacturing plants, all new kilns are subject to a THC emissions limit of 24 parts per million volume (ppmv), which would include most VOC’s. EPA believes that it has adequatel y addressed VOC limits and that no additional regulation of VOC is warranted. (Incidentall y, the purpose of section 111 new source standards is to protect and enhance the Nation’s air quality, not just maintain it. Asarco v. EPA, 57 8 F. 2d at 327 (D.C. Cir . 1978)). 

### 2.5 General Comment : One c ommenter ( 73 ) agrees with EPA that BACT determinations may consider site specific factors, but the commenter states that a BDT determination must account for factors that may have affected a site

- specific BACT determination but may not be applicable to the industry as a whole. The commenter states that as required under §111(a)(1) and was made clear in Nat’l Lime Ass’n v. EPA, 627 F.2d 416, (D.C. Cir. 1980), an achievable standard is one that can be routinely satisfied und er the reasonable worst

–case conditions that can be expected within the industry or source category

as a whole. The commenter states that EPA must rely upon data that accounts for variability within the industry as a whole and where test data is relied upo n, EPA must have a reasonable basis for believing that the available data is adequately representative of the industry

as a whole (See Portland Cement Ass’n v. Ruckelshaus, 486 F.2d 375 (D.C. Cir. 1973); Lignite Energy

Council v. EPA, 198 F. 3d 930 (D.C. C ir. 1999) )

. According to the c ommenter , EPA failed to satisfy the requirements of §111(a)(1) in making BDT determinations using limited data and extrapolating to establish a standard which EPA speculates can be achieved on a national basis. According to th e commenter, EPA has not considered adequatel y the significant factors including regional/site

- specific variations in raw mix which affect the fuel inputs required to manufacture cement (burnability in EPA’s lexicon), variations in fuels employed which aff

ect NO x emissions per ton of clinker produced, and types of cement produced which affect the required heat input and intensity per ton of clinker produced. Moreover, EPA has not taken into proper consideration specific design variations that could or must be employed to assure product quality (alkaline by

-pass) and design variations intended to reduce the energy

required to produce a ton of clinker (clinker cooler ducting to the raw mill). The commenter states that using this inverted approach, EPA has conc luded that application of BDT supports the proposed NSPS standards for NO x and PM which exceed current BACT determinations. The commenter states that NSPS standards should constitute the BACT floor setting, in effect, the lowest common denominator which cu rrent control technology

should be able to achieve on an industry

- wide or source category

- wide basis. BACT determinations should then afford individual permitting authorities, on a case

- by

- case basis, the ability to establish emission limitations more stringent than the industry

- wide denominator. This is not to say that BDT, like BACT, cannot be technology forcing. However, when EPA proposes to adopt as BDT emission limitations more stringent than current BACT, it must support its decision with sound data and anal ys is and, according to the commenter, EPA has not done this.11

Response : These general comments are addressed below along with more specific comments on the NO x and PM limits. However, if the commenter is arguing that all new sources must be able to achieve a promulgated NSPS, this is not correct, since that would negate the whole notion of use of Best Demonstrated Technology

. The commenter is correct that EPA must make a reasoned demonstration that sources utilizing the technology which is the basis of BDT should meet the standard, and that this requires EPA to fully assess potential variability and account for it in the standard. EPA believes it has done so here. For example, for NO x , we document that existing sources with particularly hard

- to

- burn inputs are nonetheless achieving the promulgated limit using SNCR (along with appropriate baseline control measures)

. We also explain how both our assumed baseline for application of end

- of

- stack controls, and our assumptions as to emission reductions achievable with (end

- of

- stack) SNCR are relatively conservative in order to account for potential variability

. Comment: One commenter (57) states that p roposed sections 60.62(a)(3), 60.62(a)(4)(i) and 60.64(c) mention a 30

- day rolling value for NO x and SO 2 . How ever, the rule language does not clearl y indicate whether the period is 30 calendar days or 30 operating days. Section 60.63(l)(1) mentions “kiln operating days” and 60.63(n)(3) mentions “boiler operating day

. ” This suggests that EPA intends the 30

- day rol ling period to be 30 operating days, not calendar days. The rule text needs to clarify EPA’s intent. Response : The commenter is correct. The 30

- day rolling average applies to operating days. The rule has been clarified

. Comment : One commenter (57) states that a ssuming that EPA intends to use operating day s; the rule needs to define a “kiln operating day

. ” EPA may want to use the boiler operating day definition from 60.41Da. Response : The rule has been clarified to describe an operating day

.12 

### 3 Applicability 3.1 Modified Kilns Comment : Several c ommenter s ( 61 , 64 , 73 , 83 ) do not believe that EPA has sufficient data to support application of the NO x and SO 2 emissions limits to modified wet process kilns which are based on data for new PH/PC kilns equipped wit h SNCR and scrubbers. Commenter 61 has been unable to find data to support an appropriate percentage reduction that could be attained from installing SNCR on a wet process kiln. According to the commenter, EPA indicated that older kilns are ty

picall y repla ced with new PH/PC kilns rather than being modified or reconstructed. Commenter 73 believes that EPA erred in its assumption that all modifications would result in older kilns ( including older

- design PH/PC) being replaced with modern PH/PC technology kilns and that EPA did not evaluate any emission data from existing kilns other than PH/PC kilns ; h owever, to establish standards applicable to modifications, EPA must evaluate what might be achievable b y the universe of existing kilns which might undergo phys i cal changes or changes in method of operation resulting in a “modification” within the meaning of 40 CFR 60.2

. Commenter 61 further stated that the EPA identified two instances of kilns modified where the proposed limits would apply but believes the kilns were actuall y reconstructed in way s which it may be appropriate to require the reconstructed source to meet the limits for new sources. Commenter 61 stated that EPA should develop separate NO x and SO 2 standards applicable to modified wet kilns and modified long dry kilns. Commenter 73 states that m odern PH/PC kiln technology is capable of achieving substantiall y lower uncontrolled NO x and SO 2 emission rates than older kiln technology . For NO x , this is due to staging combustion and burning a significant amount of fuel in the precalciner, which generates little or no thermal NO x . For SO 2 , greater trapping of sulfur in the clinker is possible through oxidization in the preheater and routing of gases from the kiln and precalciner to an in

line raw mill. The commenter states that EPA needs to assess the range of uncontrolled emissions for each type of kiln configurations and evaluate the effectiveness, cost and other statutory factors relevant to available retro

- fit control technology for each kiln ty

pe and possibl y create subcategories for the different kiln ty pes One commenter (64) states that changes such as replacement of an induced

- draft fan with one of greater capacity can trigger NSPS and that an increase in production rate of any amount can trigger NSPS i f it requires a capital expenditure and that such changes would not provide the opportunity

to incorporate process design elements that would allow the kiln to meet the newl y proposed limits or would add costs and delay s to add such process designs that far exceed the change that triggered the NSPS “modification” provision. This interpretation, according to the commenter, would create disincentives for efforts to improve energy efficiency

at cement plants if minor adjustments to the process would trigger new, more stringent emission limits, which could result in substantial outlays of capital and operating costs as well as delays associated with the designing, purchasing, and installing new pollution control equipment to meet the more stringent emission limi tations. The commenter states that because EPA assumed that only new or reconstructed kilns would be preheater/precalciner designs, their anal ys is of costs and economic impacts is faulty . The commenter provided estimates of the costs that may be incurred a s a result of modification

- triggered retrofits at an existing facility . The commenter states that EPA could also create a separate subcategory for plants that have not yet been modified to use the newer13

preheater/precalciner technology and that modificatio ns at such plants would only be subject to the current PM NSPS limit of 0.3 lb/ton of feed. This commenter states that EPA has applied different NSPS limits to facilities with different process designs to distinguish among classes, ty pes and sizes within c ategories of new sources for the purpose of establishing standards One c ommenter ( 73 ) states that AP

- 42 lists uncontrolled emission factors for wet process, long

dry , preheater, and older design PH/PC kilns of 7.4, 6.0, 4.8, and 4.2 pounds of NO x per ton o f clinker produced, respectively compared to an uncontrolled emission rate for modern PH/PC process kilns as estimated by EPA to range between 2.5 and 3.0 pounds of NO x per ton of clinker. Commenter 73 operates seven wet process kilns in the US with annual uncontrolled emission rates ranging between 6.7 and 14.1 pounds of NO x per ton of clinker and seven long

dry process kilns in the US with annual uncontrolled emission rates ranging between 5.3 and 10.9 pounds of NO x per ton of clinker. Achieving the propo sed NO x limit (based on appl ying SNCR to PH/PC kilns) with modified older technology kilns will not always be possible due to the inherentl y higher uncontrolled NO x rate. SNCR has not been demonstrated to achieve this level of reduction on wet process kiln s. One commenter (83) states that the assumption of maximum NO x emissions of 3.0 lb/ton of clinker and a 50 percent reduction using SNCR are not appropriate for exiting kilns. The commenter points to EPA’s Alternative Control Techniques Document which show s the performance of the different kiln ty pes (that is wet, long dry , preheater, and preheater/precalciner) can be well above 3.0 lb/ton of clinker. The commenter supplied data in the form of a chart showing the performance of SNCR at several of their plants. They used the chart to show that SNCR often achieves less than a 50 percent NO x removal rate. According to the commenter, this is significant because if an existing kiln triggers PSD as a result of increased annual emissions, they

must meet an emission limit achievable through the installation of BACT. The commenter states that the CAA requires that BACT cannot be less stringent than emissions allowed b y any applicable standard established pursuant to section 111. The commenter states that even if a modification of an existing kiln does not trigger the NSPS, the final NSPS is important to existing kilns as it will establish BACT for all existing kilns. Response : At proposal we had one set of emission limits for PM, SO 2 and NO x that were applicable to all new, reconstructed, and modified kilns. Commenters expressed concerns of the ability of a modified kiln to meet the same limits as a newl y constructed kiln (a so

- called greenfield new source). EPA intends that the revised rule appl y to new , modified or rec onstructed kilns that are PH/PC kilns. As discussed in the proposed rule, all kilns built since 2000 have been of the PH/PC design and the industry confirmed that any

new kiln would be of the PH/PC design . Ty

pically , older kilns are replaced with new PH/PC kilns which allows for increased capacity and more energy

efficient operation. We did identify two instances in which a dry kiln and wet kiln were substantially modified rather than demolished and replaced with new kilns. Because these were the only two instances identified since 1990, we do not expect such modifications to be common. In both cases, the kilns as modified included a preheater and precalciner which w ere b expected to be able to comply with the revised limits. Inthis final rule we are still including modified kilns as an affected source. If we were to exempt modified kilns, then such sources would be free to increase emissions without application of BDT. This would undermine the basis of section 111 standards, where Congress wanted to assure that BDT was applied to modified sources qualifying as “new”. Commenters had also claimed that other14

regulatory

programs, most notably

new source review, would result in a site specific BACT determination if emissions increased. Though we are alway s mindful of the interrelationship of different EPA regulatory

programs and their effects, we do not see this as sufficient reason to exempt modified kilns from the NSPS. For a modification to cause a kiln to become subject the NSPS, the modification must result in an increase of the hourl y emission rate of the pollutants subject to the regulation. Furthermore, major sources undergoing a modification may trigger New Source Review (NSR) and the requisite RACT, BACT or LAER review. However, we do not think that it is likely that an owner or operator would modify a kiln in such a way

as to cause it to be subject to the revised NSPS or trigger NSR. It is more likely that if a modification would otherwise result in an increase in hourly

emission rates, the owner or operator would take necessary measures, either install the necessary

add

- on controls or make process adjustments to avoid making itself subject to an NSR review as well as subject to the new NSPS limits. The PM and SO 2 limits are based on control technologies that can be applied to any kiln ty pe and achieve the same control levels that would be expected with a new kiln. So we see no issue here. Furthermore, in our analysis of the impacts of the final NESHAP, we determined that in order to meet the final limits f or HCl, nearl y all kilns would require the use of wet scrubbers. As a result of controls for HCl, emission s of SO 2 will be lowered as well as HCl emissions

. In such cases, we expect that the kilns will be able to comply

with the limits for SO 2 . For kilns t hat are near the limit, process changes such as the burning of low sulfur coal, as already required in some state permits, may help to ensure compliance with the final SO 2 limits. EPA did not intend that the revised standard appl y to older wet or dry kiln s undergoing minor modification s, unless they are substantiall y modified to the extent described above. We understand that it would not be reasonable to expect in most cases for older wet and dry kilns to comply with the new limits, especially the limits f

or NO x . These kilns require higher temperatures and longer residence time to dry and calcine the feed resulting in greater production of NO x in comparison to PH/PC kilns. Inthe case of NO x , o nce we had determined that modified kilns would be an affected s ource, we then determined if we should set a different NO x emissions limit. However, we believe it is environmentally most advantageous to retain the 1.5 lb/ton clinker limit for modified kilns. We note that there are kilns of older design that meet levels below 1.5 lb/ton clinker, and in some cases below 1.0 lb/ton clinker, with SNCR control. So modified kilns would not necessarily be unable to meet the 1.5 lb.ton clinker limit. Sources that determine the 1.5 lb/ton limit is not achievable without control still have the option of adding NO x control and avoiding the triggering of the modification provision and PSD for NO x . The NO x control available to cement kilns, in addition to SNCR, are conversion to indirect firing, mid

- kiln fuel injection, mid

- kiln air injection, and substitution of steel slag for some limestone. Given these available controls, we believe it would be extremely unlikel y that a source that determines the 1.5 lb/ton limit is not achievable would be unable to appl y s ome ty pe of NO x control that would avoids triggering the modification or PSD provisions. Comment : One c ommenter ( 73 ) opposes the application of the proposed SO 2 standard to modified kilns . The commenter states that SO 2 is primarily a function of the form and concentration of sulfur present in the limestone utilized by a cement plant. Older kiln technologies are less efficient at trapping SO 2 in the clinker than modern PH/PC designs. O nly modern PH/PC kilns with extremely high limestone sulfur concentrations will require extensive15

c ontrols to meet the proposed NSPS limit. However, for a majority of the older technology kilns, the only control option that can assure meeting the proposed NSPS limit of 1.33 pounds SO 2 per ton of clinker produced is a wet gas scrubber. Retrofit capital c ost to install a wet gas scrubber on a ty pical wet or long

- dry

kiln is in the neighborhood of $15

- 25 million dollars. For these older technology

kilns, this ty

pe of cost is not economically feasible, particularl y for minor modifications that would have very little impact on overall emissions. Response : See the previous response. Comment : One c ommenter ( 73 ) opposes revising the NSPS standard for PM emissions from modified kilns. All cement kilns operating in the U

. S

. utilize PM controls. Two primary types o f controls are used : baghouses and electrostatic precipitators. In deriving the proposed PM NSPS limit, EPA only

looked at baghouses with membrane bags. New or reconstructed kilns would be designed with modern baghouses that could incorporate membrane bags . However, existing plants may

not have this capability , or the plant may operate an ESP which may not be capable of achieving the same level of PM reduction as a new modern baghouse with membrane bags. Response : See the previous response. In addition, un der the final NESHAP, many plants will install activated carbon injection (ACI) s ys tems for the control of mercury , organic HAP and THC emissions. Because ACIs ys tems will be installed after existing PM devices, they will use a polishing baghouse to remove the carbon from the exhaust gas stream. As a result, the owner or operator of a kiln controlled with an ESP will in most cases be able to meet the limits for PM because of the additional downstream PM control device.16 

### 4 Emission Limits 4.1 General Commen t : One c ommenter ( 74 ) stated that once the U.S. EPA sets new emission l imits, local agencies may dictate emission limits that will be even lower on specific projects. The commenter c ites examples of this and recommended that the new NSPS limits be stringent and achievable for 100 percent of cement plants nationwide. The commenter states that, c onsequently , all plants will have achievable limits on a national basis and the ability to meet even lower emissions due to local requirements that are evaluated on a case - by

- case basis. Response : The purpose of the NSPS program is to ensure that the best demonstrated emissions control technologies are installed as industrial infrastructure is modernized. Such plants are to meet standards reflecting Best Demonstrated T echnology

. A standard that could be met by 100 percent of the industry ( a priori) is highly unlikel y to reflect BDT . EPA is aware that cement plants vary

from one another in their raw materials, fuel and cement product and that the details of the combustio n and pollution control technolog ies required to meet these new limits may require site

- specific adjustment . In setting the new limits for NO x , SO 2 and PM, EPA understands that some new, reconstructed or modified kilns will find it a challenge to meet the new limits while others will not. EPA is also aware that state and local agencies can set limits more stringent than those in the revised NSPS and expects that they will as local circumstances dictate , especially

for efforts to attain various of the applic able National Ambient Air Quality Standards. 

### 4.2 Format Comment : C ommenter s ( 68 , 71 ) support EPA ’s proposed limits in lb/ton of clinker over the previous lb

-per - ton of dry feed limit as the new limits avoid rewarding a source for becoming less efficient (i .e., requiring more feed to produce a unit of product). Response : EPA notes the commenter’s support

. 

### 4.3 NO x Comment : Several commenters (59, 60, 63, 68, 70, 71, 72) approve of the proposed limits for NO x or believe more stringent limits are appropriate. O ne c ommenter ( 59 ) states that the proposed standard is unjustifiably high, and will allow for greater NO x emissions than can be achieved with the installation of off

- the

- shelf pollution control technology

. The c ommenter recommend s that the new performance standard require emissions no greater than 0.5 lb NO x/ton clinker and states that SCR is an effective and proven technology to reduce NO x emissions from cement kilns and can reduce NO x emissions from cement kilns by greater than 90 percent , consistent with what has been observed with SCR in other industries. According to the commenter, SCR can achieve this performance with cost effectiveness of approximately $1 , 500

- $ 3 , 800/ton NO x , easil y within regulatory cost thresholds for many NO x control programs

. Regarding concerns over dust and plugging, the commenter cites three recent installations of SCR on cement kilns that show that SCR vendors can properl y design and install units which manage the dust and successfully operate for many years. The commenter stated that numerous17

SCR companies believe that they can design and supply

SCR sy stems for NO x control at cement plants where they

will have to guarantee performance levels in legal contracts, and thus, they would be at significant financial risk to advertise an d sell an SCR system that was actually going to fail. The e ffectiv eness of the technology to reduce NO x and other pollutant emissions from cement kilns, as demonstrated b y the SCR installations on cement kilns in Europe and the numerous SCR installations o n other heavy industries like coal

- fired power plants and waste incinerators is supported by the marketing, technical assessments, and reports prepared by numerous experts on this subject, including: three (3) cement companies, five (5) SCR manufacturers, an independent blue ribbon panel, the U.S. EPA (twice), and the European IPPC. Commenter 68 believes that EPA’s proposed NO x emission limit of 1.5 lb/ton clinker seriousl y underestimates the reductions that are achievable with SCR technology and recommend s that SCR be identified as BDT for this sector and is “the regulated future” for cement kilns. The commenter states that the agency has noted that hybrid combinations of SNCR and SCR could be used in new cement kilns to achieve greater reductions than would be possible with SNCR alone. Like SCR, we have no evidence of this combination being applied here or elsewhere. SCR is also named by

EPA as available technology for cement kilns in the Regulatory Impact Analysis for the Final Clean Air Visibility Rule or the Guidelines for Best Available Retrofit Technology

(BART) Determinations under the Regional Haze Regulations. In fact, as far back as 1999, EPA included SCR in a list of control technologies available for both dry and wet cement manufacturing process es, as did a Pechan & Associates Report prepared for EPA’s Office of Air Quality Planning and Standards in September 2005. Therefore, SCR technology for the cement manufacturing sector has been considered feasible technology by EPA for some time. While the commenter applauds EPA’s decision to add NO x to the NSPS for cement kilns , this commenter recommend s that EPA adopt SCR as BDT stating that NO x contributes significantly to ozone formation, which poses potential health risks to the more than 100 million individuals who live in areas that failed to attain the health

- based primary standard for ozone. The NO x contributions of the p ortland cement sector must, therefore, be viewed against this dismaying context of the increasing impacts of ozone pollution on human health and the environment. One c ommenter ( 60 ) states that the NO x emission limit should be lowered from 1.5 lb of NO x/ton of clinker on a 30 day

rolling averages to 1.0 lb/ton of clinker on a 24 hour rolling average for new PH/PC kilns and a limit added of 2.0 lb/ ton of clinker on a 24

- hour rolling average if reconstruction or modification of the kiln commences after June 16, 2008, and the final configuration is a long wet kiln or a long dry kiln. The c ommenter states that the recommendations regarding PH and PH/C kilns should apply equally to projects at greenfield sites and to projects at brownfield sites stating that m any of the advances in NO x control in the U.S. and Europe have been made at brownfield sites whether they have involved new kilns or reconstruction or modification of existing kilns. To support the commenter ’ s recommended limits for NO x , the commenter provided the following information and included several supporting documents as attachments to the comments:

 A long

- term value of 1.46 p ounds per ton (lb/ton) of NO x clinker was achieved with no add

- on control equipment when not accounting for slag use and 1.38 lb/ton when accounting for slag use at TXI Kiln 5 (a PH/C kiln) in Midlothian, Texas

.18

 A long

- term value of 1.98 lb/ton was achiev ed with no add

- on control equipment at Cemex Sta. Cruz (a PC/H kiln) in Davenport, California . The project involved an improvement to an existing calciner (commissioned in 1997) on an existing kiln to comply with an existing NO x limitation.

 Titan America (a PH/C kiln) in Medley Florida and Giant Cement in South Carolina where average values of 1.62 and 1.88 lb NO x/ton were documented for new kilns with no add

- on control equipment at brownfield sites.

 The results from the existing SCANCEM (an affiliate of Lehigh) Skövde PH kiln where emissions were reduced from 4.4 lb NO x/ton (1995) by installation of a SNCR system and which achieved 0.72 lb/ton in 2005.

 The results from the existing SCANCEM Slite PH/C kilns where emissions were reduced from 4.0 lb NO x/ton (1995) by installation of an SNCR system and which achieved 1.01 lb/ton in 2005.

 The results from the existing Radici Cementeria di Monselice PH kiln where emission reductions to values as low as 0.20 lb NO x/ton were demonstrated by installation of a SCR system. The supplier guaranteed reduction of 90 percent and realized reductions as high as 97 percent

. Commenter 60 states that based on the foregoing, it is clear that reductions on the order of 75 percent are achieved b y well

- designed SNCR sy stems and 9 0 percent by SCR. Given that a new kiln can be designed such that emissions can be controlled to values between 1.5 and 2 lb/ton before add

- on control, it is clear that 1 lb/ton is easily achievable by

SNCR. Given a kiln with less sophisticated design or p articularl y difficult raw materials achieving 3 to 5 lb/ton, it is clear that SNCR or SCR or a combination of the two can readil y reduce emissions to values much less than 1 lb/ton. The commenter states that the proposed averaging time of 30 days is a trem endous concession to the industry . The availability of reagent injection makes it easier to achieve the proposed standard on a 24

- hour basis. The lowest permit limit for a project under construction in the United States applies to the Drake Cement in Arizo na. The value is equivalent to 1.14 lb/ton on a 24

- hour basis. A contract was awarded to F.L. Smidth who developed the calciner that achieves 2 lb/ton or less at TXI, Titan and Cemex as discussed above. The limit will be readily achievable using an SNCR sy stem. The commenter provides additional details on the history and performance of NO x process controls (such as SCC) and add

- on controls (such as SNCR) in the US and elsewhere

. One c ommenter ( 60 ) states that b ecause long wet and long dry kilns use much more energy to make a ton of clinker, a higher NO x limit may be acceptable for these kilns . Commenter 60 agrees with EPA’s assumption th at new projects triggering the NSPS will actually result in a PH/C kiln. A project that might trigger a p revention of s igni ficant deterioration (PSD) review at a long kiln will probabl y incorporate emissions control measures to avoid PSD and a BACT determination for NO x and SO 2 . The measures to avoid PSD will also likely avoid the short

- term emissions increases that would otherwise trigger the NSPS. Finally , with respect to the reconstruction provisions, it is not likely that a company

will actually

invest 50 percent of the value of an existing long kiln without taking the opportunity to make it much more energy efficient throu gh conversion to a PH/C kiln. The commenter states that a separate standard for long kilns will avoid the unnecessary relaxation of the limits applicable to PH and PH/C kilns.19

The commenter listed the following NO x reduction technologies that have been dem onstrated for long kilns and submitted supporting documentation as attachments to the comment :

 Conversion from direct to indirect firing in conjunction with the installation of a multi

channel (Low NO x ) burner ;

 Mid kiln fuel injection (including tires) ;

 Ne ar mid

- kiln pressurized air injection;

 SNCR at long kilns; and

 Combination of SNCR with air injection. One c ommenter ( 63 ) described the advances in technology for controlling NO x emissions , especiall y SNCR and SCR, from p ortland cement plants, and requests EPA to fully consider the technological improvements and their applications when establishing NO x emission limits for the p ortland cement manufacturing industry

. The c ommenter states that EPA continues to play a crucial role in encouraging innovation and in mobilizing supply chains to deliver technologies that improve our air quality and environment including the continued tightening of emission limits. This encourages the industries such as the cement industry to work closely

with equipment and component suppliers to ensure significant reductions in emissions in a timely and economical manner. The commenter states that with the improved processes that lower uncontrolled NO x emissions and with the addition of SCR, NO x limits of 0.25

- 0.5 lb NO x /ton clinker are achievable. One c ommenter ( 70 ) supports the proposed level for new, modified and reconstructed kilns of 1.50 lb/ton of clinker for NO x . Facilities can meet the 1.50 lb/ton of clinker for NO x , with SNCR alone or with SCR (either as a supplement or as an alternative to SNCR). One c ommenter ( 71 ) states that i f new or modified sy stems would likel y use the preheater/precalciner configuration, then what is achievable must be looked at and then appl y the effect of the controls. If this approach is followed, th e appropriate NO x emission limit should be in the range of 1.14 lb/ton of clinker. According to c ommenter 71 , the traditional long dry cement kilns can attain a NO x emission level of 2.73 lb/ton of clinker without utilizing SNCR control technology . Based o n a SNCR control efficiency of 50 percent , a NO x emission level of 1.3 lb/ton of clinker is achievable. As a result, cement kilns with SNCR control technology can achieve a NO x emission level between 1.14 and 1.3 lb/ton of clinker. However, this commenter believes that the NO x emission level from cement kilns can be further reduced by utilizing SCR control technology . Commenter 71 states that EPA dismisses the SCR technology used in Europe for the most trivial of reasons. Commenter 71 concedes that some mechanical problems were experienced in the earl y s tages with plugging but these problems were resolved and the s ys tem remained in service for four years at the Solnhofen facility in Germany

. According to the commenter, waste disposal should not be an issue b ecause the spent catal ys t could be added to the process as a source of alumina. Commenter 71 previously conducted a Best Available Retrofit Control Technology (BARCT) assessment for a cement plant in our area and recommended SCR as the BARCT for this facil ity.20

One c ommenter ( 72 ) states that the NSPS emission rate for NO x from cement plants should be lowered to 0.5 lb/ton of clinker on a 24 hour rolling average because of the ability of current plant design s to achieve very low rates of NO x emissions without the addition of add

- on pollution controls. Currently available add

- on controls can reduce NO x emission levels below the proposed 1.5 lbs of NO x per ton of clinker. There is a considerable operational experience with SNCR that shows it’s capable of reducin g NO x emissions to 1 lb or less /ton of clinker when combined with a modern

- designed kiln. SCR has been demonstrated in the utility industry and Europe and can further reduce emissions. Response : See the preamble for the response. Comment : Several c ommenter s ( 64, 73, 74 , 75, 76, 77 , 78 ) commented on the difficulty of consistently

achieving the NO x limit of 1.5 lb/ton clinker limit over time and at all new kiln locations and favored a somewhat higher limit or no limit

. They state that it is important to note that consistent, long term compliance with this proposed limit may be difficult to achieve and there will be instances where compliance may not be possible at all. Different factors can influence NO x emissions such as: (1) Fuel type/quality - lower volatility solid fuels such as petcoke produce higher NO x emissions. Also, any

problems with fuel quality as delivered to the plant can have a negative impact on NO x emissions; (2) Raw mix burnability

- harder burnability will give higher NO x emissions. Burnability is dependent on the raw mix chemistry, fineness, and chemical deviation (impacted by homogeneity

and operation of the quarry , which can vary over extended periods of time); (3) Kiln by

pass s ys tem

- The size of the by pass for a given plant (if needed), and consequently

the b ypass emissions, depends on the chemistry of the raw mix and fuel(s) and the product standards that must be maintained to comply with regulations; (4) Size/ty

pe of the preheater

- new in

- line calciners will normally give the lowest NO x emissions; however, in cases where the type of fuel(s) used dictates the need for a separate calciner (such as may be applied to utilize waste materials), NO x emissions will be higher. In addition, sometimes a new project will consist of upgrading an existing py ro sy stem . In many of these cases the layout of the existing equipment is such that it cannot be modified to perform as well as a brand new calciner s ys tem, and will therefore have higher NO x emissions; (5) Sub

- standard operation and maintenance of the kiln system

- this is the responsibility of the cement producer, but it is also expected that NO x emissions will increase slightly over a ty pical campaign between annual maintenance stoppages due to normal “wear and tear” of the system; and (6) SNCR efficiency

and slippage

- the ability of an SNCR system to reduce NO x emissions is not the same for all s ys tems, especiall y for an existing pyro s ys tem that has been upgraded (due to potential lack of an optimum injection point) or a very large p yro sy stem (due to lack of optimum m ixing of ammonia and preheater gas).21

One c ommenter ( 75 ) states that although the removal efficiency of SNCR can theoretically be improved by

increasing the quantity

of ammonia injection, there is a practical limit to this approach. As ammonia injection rates increase, the potential formation of a secondary plume due to “ ammonia slip ” increases. In addition, sulfur in the raw materials results in SO 2 and S O 3 in the exhaust, which decreases the efficiency of ammonia injection and leads to operational issues such as solids accumulation and plugging downstream of the SNCR. As the commenter noted in the permit application for its proposed kiln, facilities with lower BACT emission limits are also those facilities with lower sulfur raw materials, notably plants lo cated in Florida, thereb y improving the efficiency

of SNCR. Given the baseline NO x emissio ns expected at a new plant, Commenter 75 would need a control level of at least 70 percent to meet the proposed limit of 1.5 lb/ton. Commenter 75 is not confident that this can be done with SNCR. Therefore, the commenter recommends that the NO x standard be established at 1.95 lb/ton , which reflects a level of control achievable with the use of SNCR by all facilities without introducing the negative effects associated with pushing for high control levels. One c ommenter ( 76 ) states that a ssuming a facility is already

operating with best combustion practices ( i.e., indirect fired fuel suppl y s ys tems, low primary air burners, etc.) then the burnability

of the raw mix has th e greatest single impact on NO x emissions. Statistically speaking, most preheater precalciner cement kiln plants worldwide emit an uncontrolled NO x emission of 3.8 to 4.2 lb NO x/ton of clinker. With a 50 percent NO x reduction rate from the application of S NCR technology , a controlled emission rate of 1.9 to 2.1 lb NO x/ton of clinker could be expected for most kilns. As such, a 1.95 lb NO x/t clinker limit for all new kiln applications seems achievable. The issues arise when people arbitraril y apply the 50 pe rcent reduction potential of SNCR to lower baseline emission numbers. ( i.e., at a 3.2 lb NO x/ton of clinker uncontrolled emission, SNCR could reduce it to 1.6 lb NO x/ton of clinker). While this might be true on an isolated case basis, it would be unwise to approach such a low level for a new NSPS limit for all new kilns because of the issue of burnability

. In some cases it might be possible to reduce the baseline NO x levels with integrated control systems, such as Multi

- Stage Combustion (MSC) installed on l ow NO x calciner sy stem; but here again, the practicality of sustaining stable, continuous operation while simultaneously reducing the baseline NO x by 10 to 30 percent is very

site specific. Commenter 76 believes that a controlled emission rate of 1.95 lb N O x/ton of clinker can be achieved b y all new kiln applications providing SNCR is used as the principle measure to control NO x emissions, but excluding that portion of gases that may be extracted through a b ypass system. One c ommenter ( 77 ) believes that un der the worst

- cast combinations of raw materials, fuels and cement specifications and with the application of SNCR technology , a controlled emission rate of 2.0 lbs of NO x per ton of cement clinker can be achieved by all new kiln applications. However, if the kiln must incorporate a by pass for alkalis, chlorides or sulfur, the NSPS limits must allow for increased NO x emissions on a plant by plant basis due to the fact that by pass amounts can be anywhere from 5 percent to 100 percent in size. One c ommenter ( 78 ) states that very few kilns with alkali by

passes would have a chance of meeting the proposed limit on a long

- term basis. One commenter (83) requested that EPA clarify whether the NO x lim i t applies only to a kiln’s main stack or whether it applies across both the main and by

pass stacks.22

One commenter (73) believes that EPA failed to identify and appropriatel y consider the variables that affect uncontrolled NO x emissions from modern preheater/precalciner kilns employing SCC and LNB on an industry

- wide basi s. As a consequence, EPA relied upon too limited a database that did not reflect these variables and then made assumptions reflecting an incomplete understanding of the range of variability in uncontrolled NO x that result from them. Commenter 73 recommends that EPA revise its proposed baseline NO x emission standard from 1.5 to 2.0 lb/ton of clinker, and allow for adjustments of the standard upward from this value when by passes are used, unusually hard burning raw mixes are used, or specific clinker ty pes (s uch as o il well clinker) that require non

- ty pical burning methods is being produced. When by passes, hard burning mixes and/or clinker specifications require non

- ty pical operational parameters, an adjustment factor should be allowed and evaluated on a case

- by

- case basis. The fact that individual kilns may

be able to achieve a NO x emission rate as proposed b y EPA (or even lower rates) is not determinative of what is an appropriate standard for the NSPS. Commenter 73 states that fuel volatility plays a major role in NO x emission control. The uncontrolled NO x generated in the precalciner alone can vary by as much as 1.4 g/kg of clinker (2.8 lb/ton clinker) based on fuel volatility . Commenter 73 states that modern preheater/precalciner kilns fire approximately 55

- 65 percent of their fuel in the precalciner. The nitrogen content in the fuel is the main factor affecting fuel NO x formation. The fuel NO x produced in the precalciner is not directl y proportional to the nitrogen content of the fuel. It also depends on th e chemical form of the nitrogen in the fuel and the volatility of the fuel. Ty

pically , fuel nitrogen in coals used by PH/PC kilns varies between 1.0 and 2.0 percent. This difference can impact the uncontrolled NO x by as much as 1.5 lb/ton of clinker. Commenter 73 states that a PH/PC kiln system uses hot gases from the kiln to both dry and heat the raw materials prior to calcination. The effectiveness of this system is related to the moisture content of the raw materials and their ability to absorb heat from the gases. If additional heat is required to dry

or heat the raw materials, gases from a separate fuel

- fired furnace or the clinker cooler are ducted to the raw mill. As a result, the moisture content of the raw materials directl y influences the NO x emiss ion rates. High moisture materials require additional energy to dry the materials in the raw mill and/or preheater. This increased need for energy contributes to the amount of NO x emitted if the excess energy comes from burning additional fuel. Some plants may have up to 20

- 25 percent moisture content in their raw mix

– which results in a 15 to 20 percent increase in the kiln’s specific heat consumption, as compared to a “standard” raw mix that contains approximately 5 percent moisture. This additional energy need results in the combustion of more fuel which ultimately results in more uncontrolled NO x . On NO x emissions from alkali by passes, commenter 73 states that b ecause the gases within the by pass are not allowed to remain in the optimal SNCR temperature range, SNCR is not a feasible control option for these gases. The commenter shows (in graph form in their comments) that for a certain size kiln, by

pass ing 25 percent of its kiln gases will have an incremental increase of approximately

0.42 lb/ton of clinker in the controlled NO x emission rate. Commenter 73 states that the three major kiln suppliers require a cement company to provide detailed information on raw materials (including moisture content), fuels, and clinker quality specifications prior to prep aring a quotation and specifying emission guarantees. Uncontrolled 30

- day average NO x emissions can vary from less than 1.6 to greater than 4.6 lb/ton of clinker.23

SNCR has been demonstrated to reduce NO x emissions from cement kilns ; h owever, SNCR has not b een used on cement kilns for an extended period of time. High removal efficiencies such as those stated in the preamble (i.e., 63 percent at an ammonia

- to

-NO x ratio of 1.0) may result in adverse product quality or environmental impacts that are undesirable . In addition, the use of SNCR on larger kilns (>2,000,000 ton/y r capacity) may not be as effective due to the larger calciner duct diameter and the ability for the ammonia

- reagent to mix thoroughl y with the combustion gases. Based on limited data, removal efficiencies of 25

- 50 percent appear to be achievable without these adverse impacts. Therefore, Commenter 73 believes that since NSPS is applicable to all new or reconstructed kilns, a reasonable baseline NSPS limit taking into account ty pical operating c onditions and limitations stated above is 2.0 lb/ton of clinker. However, when non - ty pical conditions exist (by pass, hard burning mixes, and specific clinkers that require non

ty pical burning methods), an adjustment upward from the baseline value is appropriate and should be made on a case

- by

- case basis. C ommenter s ( 64 , 73) state d that the proposed NO x limitations are substantially more stringent than the most stringent NO x limit that applies to cement plants in Europe, which converts to approximately

2.5 lb/ton of clinker produced although EPA asserts that this should be considered the “baseline level of control that would occur with no additional regulatory action

. The commenter states that there are several problems with that analysis : 1) It does not appe ar that this conclusion is based on a “statistically sound” analy sis, as the statute requires ; 2) I f the NSPS were set at 2.5 lbs. [sic ] of NO x per ton of clinker, then all affected facilities would have to meet the limitation continuously , rather than the “average” performance of all affected facilities being at or below 2 .5 [sic ] lb/ton. Therefore, it would appear from EPA’s rationale that setting an emission standard of 2.5 [ sic ] lb/ton would require some facilities, even if they have SCC and low

-NO x bur

ners, to implement additional NO x controls in order to comply continuously

with that standard throughout the life of the facility

. The commenter states that there may be substantial differences between the NO x emissions that can be achieved b y new, greenfi eld kilns and what can be achieved by “reconstructed,” brownfield kilns. NO x emissions are a function of fuel type and of raw material type. S ome raw materials will require longer residence time in the kiln, and perhaps at higher temperature and produces m ore uncontrolled NO x emissions, and therefore makes meeting a given emission limit more problematic and costly . The same is true of fuel that has a higher mass of nitrogen per unit of heat value. Reconstructed cement plants usuall y will have little or no c ontrol over their raw materials and may

have limited control over the fuel they can use. The commenter states that EPA also needs to address the achievability of NO x limitations at cement plants that have bypass stacks or ducts to control alkalinity becau se EPA has not presented in the preamble to the proposed rule any basis for concluding that SNCR is a demonstrated technology for meeting the proposed for facilities with by pass sy stems. Likewise, while EPA acknowledges that burnability may have a signifi cant influence on NO x emissions, EPA has not explained how these differences are reflected in its anal ys is of the BDT and the proposed new NO x limits. Cement plants with hard

- to

- burn raw materials face much greater challenges in meeting a NO x limit and app lyingSNCR.24

Commenter 64 agrees with EPA that SCR has not been demonstrated on preheater/precalciner kilns and that there are substantial unresolved issues about the potential for use of SCR at such cement plants. Commenter 64 also notes that, in addition to the cost which EPA identified as a disadvantage of a low

- dust SCR system, there would be substantial adverse energy usage and GHG consequences of re

- heating the flue gas for a low

- dust SCR system. Commenter 64 also believes that EPA has not given adequate consideration to ammonia slip from the use of SCNR. EPA seems to acknowledge that it does not have data on how ammonia slip will contribute to condensable PM emissions, and what if anything could be done to mitigate that contribution. EPA has not conduc ted a sufficient technical anal ys is to support new NO x emission limits that would effectivel y require use of SNCR without addressing the ammonia slip issues. Ammonia slip may be a particular problem when SNCR is applied to particular designs, such as p yro sy stems that have been modified or that are particularl y large. The inability of these sy stems to promote the reaction of ammonia with NO x also reduces potential control efficiency of SNCR on these sy stems. Commenter 64 believes that the best approach is f or EPA not to amend the NSPS to include NO x limits. I f EPA nevertheless insists on including NO x in the revised Subpart F NSPS, then c ommenter 6 4 recommends that for preheater/precalciner kilns (whether constructed at Greenfield or brownfield sites), a NO x emission floor of 1.95 lb/ton of clinker be established as the NSPS limit. This limit would then be modified on a case

- by

- case basis to account for site

specific factors such as the presence of a b ypass stack/duct or difficult to burn limestone or fuels, likely resulting in an emission limit in excess of the recommended floor. Response : See the preamble for the response. 

### 4.4 SO 2 Comment : Several commenters (60, 68 , 70, 71, 72 ) stated that the proposed limits for SO 2 were not sufficiently

stringent. C omment er ( 60 ) recommends deleting the 90 percent reduction option, revising the limit for SO 2 to 0.5 lb/ton clinker on a 24

- hr rolling average if the kiln is a PH or PH/PC kiln and adding a limit of 1.0 lb/ton clinker on a 24

- hr rolling average if the kiln is a long wet or long dry

kiln. Commenter 72 concurs on reducing the limit to 0.5 lb/ton for PH/PC kilns. C ommenter 60 states that for PH and PH/C kilns , the limit should apply equally to projects at greenfield sites and to projects at brownfield sites. C omment er 60 cites kiln performance at brownfield sites whether they have involved new kilns or reconstruction or modification of existing kilns : C ement plants in Florida emit on the order of 0.10 lb SO 2/ton clinker . Although these kilns have very low

- sulfur feed materials, all of them use coal and rel y on the fuel SO 2 control that is inherent in the PH and PH/C designs. The steps include reaction with alkali and incorporation into the clinker in the burning zone, dry scrubbing with finely

divided lime in the calc ination zone and moist limestone scrubbing in the raw mill

. Commenters 60 and 72 cite the performance of the kilns used by EPA to establish the proposed limit:25

The key kiln (kiln 5 at TXIMidlothian, TX) upon which EPA based the proposed the SO 2 standard o f 1.33 lb/ton has actuall y operated at 0.37 to 0.57 lb/ton. C ommenter s 60 and 72 state that raw materials in the Midlothian area are known for high

- sulfur feed materials and the TXI kiln has a wet scrubber to reduce (non

- fuel) SO 2 emissions. The limit for Kiln 5 is now approximately 0.95 lb/ton following a production increase authorized by the Texas Commission on Environmental Quality (TCEQ). TXI Midlothian Kiln 5 and two other PH/C kilns (Kilns 1 and 2) operated b y Holcim in the same city are controlled by wet scrubbers. All three have wet scrubbers yet there is a vast difference in performance between the TXI Kiln 5 and the Holcim Kilns 1 and 2. The commenter presented data on the SO 2 performance of the 3 scrubber controlled kilns. According to the commenter , the TXI Kiln 5 can consistently achieve SO 2 emissions less than 0.5 lb/ton if required b y a permit limit. The higher SO 2 values for the Holcim kilns (> 4 lb/ton) represent the first ye ar of joint operation. Thereafter , Holcim Kilns 1 and 2 were operate d at levels between 2 and 3 lb/ton. The commenter states that they can choose to run one to four pumps providing reductions in SO 2 emissions ranging from 51 percent with a single pump in operation to 91 percent with four pumps in operation. Commenter s 60 and 72 state that the Ash Grove Chanute PH/C kiln in Kansas achieves less than 0.30 lb SO 2/ton despite high sulfur in the raw materials without even using a wet scrubb er. Commenter 60 states that this performance is attained using important innovations (th e F.L. Smidth DeSO x sy stem and Environcare Micromist Lime sy stem) not yet assessed by EPA

. Attachments provided as part of the comment describes the se technolog ies

. Commenter 60 states that without controls the proposed Chanute kiln would emit SO 2 at the high rate of 12 lb/ton from raw material sources alone (i.e. exclusive of fuel SO 2 ). According to Commenter 60 , using the described technology , actual emissions from the Ash Grove Chanute kiln are less than 0.25 lb SO 2/ton. According to commenter 60, the H olcim Siggenthal PH kiln in Switzerland achieves approximately

0.05 lb SO 2/ton using the POLVITEC coke filter installed in the 1990’s . The POLVI TEC system is used with various concurrent operational practices to control NH 3 (from an SNCR system), SO 2 , PM and metals. Among several functions, the coke filter captures the non - fuel SO 2 generated in the PH. The coke is subsequently crushed and then burned with fuel in the main kiln burner. The SO 2 from the P H then behaves like fuel SO 2 and is incorporated into the clinker. Further details are available in an attachment submitted with the comment. The commenter states that SO 2 emissions would be significantly less than 0.10 lb/ton of clinker. Ac cording to the commenter , the Siggenthal plant emits much less SO 2 tha n the average of Holcim cement plants in Switzerland and clearl y l ess than 0.10 lb SO 2/ton. Commenter s 60 and 72 state that the Holcim Untervaz plant Switzerland achieves between 0.04 and 0.21 lb SO 2/ton using a wet scrubber despite, according to commenter 72, the presence in the limestone of iron sulfide . Holcim initially installed a dry

scrubber at the Untervaz plant in the late 1980’s. Recent data provided b y the commenter indicate significant reductions in SO 2 emissions from since 2002 largel y due to th e replacement of the older dry scrubber with a more efficient and economic wet scrubber. According to commenter 60, the areas where medium sulfur raw materials are present can implement programs similar to the Ash Grove installation without installing large wet scrubbers,26

dry scrubbers or coke filters. Finall y selective mining of the available raw materials with respect to sulfur content is an important SO 2 control strategy for any new project. In summary , Commenter 60 recommends an NSPS SO 2 limit of 0.50 lb/ton of clinker on a 24

- hour basis for PH and PH/C kilns. Commenter 60 states that b ecause long wet and long dry kilns use more energy

to make a ton of clinker, a higher SO 2 limit may be acceptable. Commenter 60 agrees with EPA’s assumption that new proj ects triggering the NSPS will result in a PH/C kiln. A ccording to the commenter, project s that might trigger a PSD review at a long wet or long dry kiln will probably

incorporate emissions control measures to avoid PSD and a BACT determination. The measure s to avoid PSD will also likely

avoid the short

- term emissions increases that would otherwise trigger the NSPS. With respect to the reconstruction provisions, the commenter states that it is not likely that a company will actually invest 50 percent of the (undepreciated) value of an existing long kiln without taking the opportunity to make it much more energy efficient through conversion to a PH/C kiln. Nevertheless, the commenter states that it is advisable to separate out the (unlikel y) long kiln projects that trigger the NSPS without resulting in PH or PH/C kilns in order to avoid the unnecessary

relaxation of the limits applicable to the much more likely PH and PH/C kilns. According to the commenter, s crubbers are available for long kilns just as they are available for PH and PH/C kilns. Other strategies suggested cited by the commenter include 1)Near mid

- kiln pressurized air injection ; and 2) Chains near the entrance of the kiln that can improve contact between the incoming wet limestone and the SO 2 - laden exhaust gases containing both raw material and fuel sulfur. C ommenter 60 states that good SO 2 control will make it possible to employ more aggressive NO x control and that the control of NO x and SO 2 will also minimize the formation of ozone and fine PM in the environment. Commenters (68, 70, 71) states that State and local experts, who have had long experience with this industry, believe that the proposed NSPS limit for SO 2 does not reflect what most plants are capable of achieving. Even taking into account regional variability in the py ritic sulfur cont ent of the raw materials, this commenter s finds that most cement kilns already achieve lower SO 2 emissions than the 1.33 lb/ton of clinker proposed. Commenter 70 stated that after addressing raw materials in their most recent BACT review, SO 2 limitations were 0.9 lb/ton of clinker (30

- day average) and 1.6 lb/ton of clinker (24

- hr average); considerabl y lower than the 1.33 lb/ton of clinker (30

- day average) proposed. Response : See the preamble for the respon se. Comment: Several commenters (64, 74 , 75 ) expressed concerns that the proposed limits for SO 2 are too stringent. One c ommenter ( 64 ) recommends that EPA not include SO 2 limitations because EPA recognizes that there are onl y “a few locations” where the raw materials contain high levels of sulfur, and in those few situations state regulations already i mpose SO 2 emission limitations that require the ty pe of technology

EPA proposes as the basis for the proposed SO 2 limitations. The commenter states that EPA a ssumes that one out of five new kilns will be sited where the raw materials are high in sulfur, requiring an SO 2 scrubber or a lime injection sy stem when in fact at existing plants there have only been a handful of situations where high

- sulfur27

materials have been determined to justify wet scrubbers. According to the commenter, o f 28 BACT determinations for SO 2 for cement kilns since 1998 reported in the RACT/BACT/LAER Clearinghouse (RBL C) , only 5 were based on wet scrubbers, and 1 each specified a dry

scrubber or hydrated lime injection while the majority required no add

- on controls because of low

- sulfur raw materials or reliance on the inherent process absorption of SO 2 . The commenter states that the preamble information that only 5 kilns out of 178 kilns currentl y use a wet scrubber indicates that uncontrolled SO 2 emissions are rarel y high enough to justify add

- on controls. The commenter states that EPA acknowledge s in the preamble that EPA is not obligated to promulgate NSPS for every pollutant emitted by sources in the source category

. According to the commenter, the fact that very few cement kilns have been required to employ add

- on controls for SO 2 is evidence that there are few instances where cement kilns are contributing to SO 2 NAAQS nonattainment, so there is no need for an SO 2 NSPS to address ambient air quality problems. Commenter 6 4 states that allowing state and site

- specific requirements address SO 2 at plants with high

- sulfur raw materials would address weaknesses in EPA’s proposed SO 2 standards . For example, although EPA assumes that the proposed SO 2 standards will require add

- on controls only at facilities with high

- sulfur raw materials, EPA has proposed a limit of 1.33 lb of SO 2 per ton of clinker, whereas the average emission rate from just 1 8 data points from tests at facilities with moderate levels of sulfur in raw materials was 1.3 lb/ton. EPA’s assumption that facilities with low and moderate levels of sulfur in raw materials would not have to install controls to meet the proposed SO 2 stan dards is not justified by those data. Requiring facilities with moderate uncontrolled SO 2 emission levels to use add

- on controls for SO 2 would result in excessively high costs per ton of SO 2 removed, as EPA has recognized. Also, the energy penalty associat ed with wet scrubbers could more appropriatel y be evaluated on a case

- by

- case basis, where it can be weighed against factors such as the level of uncontrolled SO 2 emissions at the particular plant and the need for further SO 2 reductions at that location fo r attainment and maintenance of SO 2 ambient air quality

standards. Commenter 64 states that because there is so little experience with add

- on SO 2 controls, EPA has relativel y little data about the performance of those controls, and is proposing NSPS for S O 2 based solel y on a recent BACT determination. The few kilns that will be subject to the proposed Subpart F NSPS can be addressed through requirements for SO 2 control derived through the RACT process or through NSR

. Commenter 64 states that i f EPA persist s in setting SO 2 standards, there are a number of problems with the standards as proposed. For example, the percentage reduction alternative does not indicate that it is to be calculated on a 30

- day basis or how the percentage reduction is to be calculated

. The commenter infer s from the monitoring provisions that EPA intends for a source to compare the SO 2 concentration at the inlet to the scrubber to the SO 2 concentration at the outlet from the scrubber , b ut this does not reflect the substantial reduction in SO 2 emissions that occurs from contact with alkaline materials in the process. The commenter states that cement plants with moderate uncontrolled SO 2 emissions may have to install controls and the 90 percent reduction standard likel y would be unachievab le when applied to the relatively low inlet concentrations to the control device. The commenter states that it is even less clear how EPA would apply

the percentage reduction standard to cement plants that choose to use lime injection28

Commenter 64 states that the proposed regulations lack any discussion of whether the SO 2 limitations apply

during periods of startup, shutdown, and malfunction. Since substantial reduction of SO 2 occurs naturally in the cement

- making process because of the alkaline nature of the raw feed, commenter 64 states it would be reasonable to provide an exemption so that a wet scrubber or a lime injection sy stem need not be operating, or operating at maximum efficiency , during periods of startup, shutdown, or malfunction. The commenter states that s everal recent BACT determinations involving scrubbers include special provisions for startup, shutdown, or malfunction. Commenter 64 states that the proposed limits for SO 2 appear inconsistent with their stated technology

bases, when compared to actual experience and to BACT determinations. According to the commenter, the majority of BACT determinations in the past 10 years that rely onl y on inherent SO 2 reduction established limits higher than 1.33 lb/ton of clinker, except for plants in Flori da, where the BACT determinations often recognized that raw materials are low in sulfur. According to the commenter, NSPS should be based on demonstrated technology that can be applied to the sector as a whole, rather than based on raw materials that are available onl y in a limited area of the country . These BACT determinations also undermine EPA’s stated assumption that 1.3 lb/ton represents a “moderate uncontrolled SO 2 emission rate” and 13 lb/ton would be “a high uncontrolled SO 2 emission level,” since almost all BACT determinations for plants other than those in Florida imposed SO 2 emission limits based on no add

- on controls higher than 1.3 lb/ton, and a number were higher than 13 lb/ton. Commenter 64 states that i f EPA insists on promulgating NSPS for S O 2 , it is essential that the standards retain the proposed option of meeting either a pounds per ton of clinker o r a percentage reduction limit , b ut both limits should be higher than proposed. According to the commenter, the three wet scrubbers operated b y Holcim were not designed to achieve 90 percent reduction, and the one BACT determination that contains an estimated percentage reduction in the RBL C uses 85 percent reduction. Importantly , cement plants in arid venues may not have the option to use a wet scrubber because of water restrictions. Especially if EPA persists in applying the revised NSPS to existing, modified or reconstructed facilities, wet scrubbers cannot be considered demonstrated available technology for all facilities in the source category. EPA does not, and Commenter 64 believes EPA cannot, support a 90 percent reduction requirement using dry scrubbers or lime injection. According to the commenter , to qualify as a limit based on demonstrated technology, the limit should be achievable at all ty pes of plants, raw materials, and locations, and should be based on actual performance data rather than what is “reportedl y” achievable or anticipated. Commenter 64 states that 1.33 lb/ton does not represent even the technology basis

—alkaline wet scru bber on high

- sulfur raw materials

—that EPA has identified. The commenter states that EPA describes one kiln where uncontrolled SO 2 emissions are “about 13 lb/ton of clinker.” Achieving 90 percent reduction of that uncontrolled emission rate would just meet the proposed mass limit, with no margin of compliance. And in any event, at least four of the BACT determinations for cement kilns in the past 10 ye ars reported in the RBL C reflect uncontrolled SO 2 emission rates over 20.0 lb/ton. The proposed limit of 1. 33 lb/ton thus does not reflect a limit that has been demonstrated as achievable applying wet scrubber technology to the range of sulfur contents present in cement plant raw materials.29

One commenter (74) states that the proposed SO 2 limit may be achievable in most cases but different plants will require different solutions to achieve that limit. Due to the large variations in the elemental and p yritic sulfur from plant to plant, Commenter 74 does not believe that it is fair to have a set SO 2 limit for all p lants. Each plant's limit should be considered on a case b y case basis considering the elemental or py ritic sulfur level in the raw materials and a reasonable target for the cost per short ton of removal to determine the controls that are used. In some cas es this will give a limit lower than 1.33 lb /ton clinker and in other cases it will give a higher limit. One commenter (75) states that: 1) Given the range of py ritic sulfur in our raw material, we would need to have a wet scrubber to meet this limit; 2) Lime injection is an effective control with less secondary

impacts on water suppl y and energy use; and 3) A limit of 4 lb/ton of clinker should be adopted. This would allow greater use of lime injection, providing significant SO 2 reductions while avoiding s econdary adverse environmental impacts and energy use of wet scrubbing. The commenter does not believe that the proposed limit adequately reflects the inherent variability

of kiln emission rates, which are dictated b y the characteristics of the raw feed to a kiln. Commenter 75’s kiln feed is locall y mined raw materials used for over 100 ye ars, with plans to continue the present mining operation for many ye ars in the future. The standard, as proposed, would impose economic and environmental impacts beyond th ose considered by EPA. Response : See the preamble for the response. Comment : One c ommenter ( 73 ) states that the proposed 1.33 lb/ton of clinker limit or 90 percent or more SO 2 reduction implies that: 1) If a kiln achieves 1.33 lb/ton of clinker without the need for any add

- on SO 2 control technology , it would meet the NSPS ; 2) If uncontrolled SO 2 emissions exiting the raw mill are between 1.34 and 13.3 lb/ton of clinker, control technology capable of reducing SO 2 emissions to 1.33 lb/ton of clinker would be required to meet the NSPS ; and 3) If uncontrolled SO 2 emissions exiting the raw mill are greater than 13.3 lb/ton of clinker, a control technology

capable of 90 percent or greater control is required to meet the NSPS. The commenter states that i f this is n ot EPA’s interpretation, then EPA should adopt the approach outlined above, and make appropriate changes to the regulatory language to make this clear. Response : The commenter’s interpretation is not entirely correct. In light of the final limits for SO 2 , i f SO 2 emissions from a kiln exceed 0.4 lb/ton clinker, the owner or operator has two options: install a control device or modify the process so that emissions are reduced to less than 0.4 lb/ton, or; install a scrubber or other control device than achieve s at least a 90 percent reduction in emissions across the control device. Comment : One c ommenter ( 76 ) states that p yritic sulfur is the main contributor to SO 2 emissions in cement plants. The Fe 2 S 2 releases its sulfur around 400°C, which fits nicel y into the fo urth stage (counting from the lowest stage to the highest) of a typical preheater temperature profile. The magnitude of the SO 2 emission is simply a calculation of the total potential SO 2 emission minus how much will be absorbed b y the system. To brin g a Colorado, or Texas cement plant’s SO 2 level down to that of a plant in Florida, would require extensive secondary abatement. In extreme cases, secondary abatement could consistently lower the SO 2 emission by 90 percent ; therefore as long as the uncontrolled SO 2 emission from py ritic sulfur and all other sources does not exceed 13.3 lb / SO 2 ton of clinker, then a continuous controlled rate of 1.33 lb SO 2/ton of clinker could be achieved.30

Response : Under the final rule, the owner or operator of a kiln must comply with the SO 2 limit of 0.4 lb/ton of clinker or reduce SO 2 emissions across the control device by 90 percent or greater. Comment : One c ommenter ( 77 ) believes that with a properl y designed state

- of

- the

- art preheater/precalciner kiln sy stem, a continuous controlled emission rate of 1.4 pounds of SO 2 per ton of clinker can be achieved b y all new kiln applications which have minimal pyritic sulfur in their raw materials. On plants with unusually high py ritic sulfur in their raw materials Commenter 77 be lieves that with add

- on controls, a reduction of 90 percent will be possible. Response : Incontrast to the commenter’s recommendation for a limit of 1.4 lb/ton clinker, kilns currentl y operating with minimal py ritic sulfur in their raw materials, for examp le kilns in Florida, have emission rates ranging from 0.02 to 0.3 lb/ton clinker (Docket item EPA

- HQ

OAR

- 2007

- 0877

- 0022 ). For kilns processing high py ritic sulfur raw materials, we agree that a 90 percent reduction is achievable. We think that a properl y designed scrubber can achieve better than a 90 percent reduction. For example, emission results from a scrubber

- controlled kiln in Texas that process es raw materials with a high sulfur content show SO 2 removal efficiencies ranging from 91 to 99 percent with an average of 94 percent (Docket item EPA

- HQ

- OAR

- 2007

- 0877

- 0022 ). Comment : One commenter (83) supports the proposed SO 2 standard of 1.33 lbs/ton clinker as a reasonabl y achievable standard. The commenter would like for EPA to clarify that the limit is stack specific as opposed to a facility

- wide limit, which means that kilns with both main and by pass stacks would not combine their emissions for compliance purposes but instead only have to meet the limit at each stack. Otherwise, the commenter states that the standard would be too stringent. Response : For a kiln with a by pass, compliance with the SO 2 limit will be determined b y measuring the SO 2 emissions from the separate stacks and summing the mass of SO 2 emitted from the b ypass and the kiln and dividing the sum by the clinker production , i.e., emissions are to be combined

. 

### 4.5 PM Comment : One c ommenter ( 64 ) supports EPA’s decision not to set separate limits for condensable PM, PM 2.5 , or PM 10 stating that these fractions of PM will be adequatel y controlled by facilities utilizing control equipment sufficient to meet the proposed limits for PM. The commenter also concurs that EPA does not have adequate data on the emissions or the demonstrated capability

of various control technologies to meet any specified l evel of these fractions of PM . The commenter states that they are not aware of any demonstrated or emerging technology

that would provide better control of PM 2.5 , PM 10 , or condensable PM emissions specificall y. Response : The PM limits address filterable PM , including PM 2.5 and PM 10 , but not condensable PM. As the commenter states , EPA does not currently have sufficient information on emissions of condensable PM from cement kilns to set emission limits . The current information on emissions of condensable PM is highly uncertain. Limited data indicate that emissions of31

condensable PM is likely site

- specific and variable. Although not quantifiable at this time, EPA expects that the combination of PM controls as well as wet scrubbers that are installed in order to comply with the HCl emission limits being promulgated in the final NESHAP amendments will result in a reduction of condensable PM , PM 2.5 and PM 10 . Comment : One c ommenter ( 64 ) agrees with EPA’s decision to not set a lower PM emission limit for clinker coo lers than kilns as they are not aware of any t echnological basis for setting a lower PM limit and agrees that data on clinker cooler PM emissions from three newer facilities are not sufficient to fully

reflect control device performance variability at a single facility or among facilities. Response : EPA is setting the same PM limit for kilns and clinker coolers although the final limits of 0.04 lb/ton clinker (existing sources) and 0.1 lb/ton clinker (new sources) are more stringent than the PM limits that were proposed

. Comment : One c ommenter ( 68 ) stated that they agree with EPA’s BDT analysis and conclusion, and supports the PM NSPS level proposed. Response : As described in the preamble, the statistical methods used to establish the MACT floor limits were revised following proposal and resulted in lower PM emission limits for existing and new sources. Even though the final limits were derived under the MACT floor anal ys is, they

also reflect best demonstrated technology and the new source MACT PM limit of 0. 01 lb/ton of clinker is also the limit for new sources subject to the NSPS

. The final PM limit is now a 30

- day

rolling average limit monitored using PM CEMS. Itshould be noted that due to the longer averaging periods, the actual limit will be less compare d to the shorter compliance interval in the proposed rule (30 day s versus a three hour test). Comment : One c ommenter ( 71 ) recommends that EPA set a PM emission limit at a level that is significantl y lower than 0.086 lb/ton clinker. Commenter 71 states that current PM emission levels from existing kilns and clinker coolers that utilize the traditional fabric bags to control emissions are in the range of 0.069

- 0.098 lb/ton of clinker. The higher end o f this range is accompanied b y visible emission. This may s uggest that th e se higher values may be the result of bag leaks. If the EPA is suggesting the use of membrane technology and bag leak detection (BLD) s ys tems, then clearly the proposed limit is not reflective of the effect of the technology

. Under normal operating conditions without bag leaks, the m embrane technology would practicall y eliminate the emission of fine (inhalable) particulate and coupled with a BLD s ys tem would result in emissions near a tenth of the proposed standard. The cost impacts would be n egligible since the real cost would be the increment b etween the traditional fabric bags and membrane technology

. In addition, the literature and experience suggest that the greatest threat to human health is fine particulate in the inhalable range. It is the fine particles which provide the high reactive surface to promote smog forming reactions. Further, it is also the f ine particulate that will impact visibility since it can be persistent in the atmosphere while the larger species settle and it has the highest ability to disperse radiation in the visible spectrum. Commenter 71 suggests that EPA should consider establishing emission limits based on PM 10 or PM 2.5 . Response : We have decided to set the NSPS PM limit at the same level as the NESHAP new source limit, 0.1 lb/ton clinker. This change would address the comment above.32

As discussed in the previous response as well as in the preamble, EPA has set the final PM emission limits at 0.4 and 0.1 lb/ton of clinker for existing and new sources, respectivel y and requires that emissions be monitored using PM CEMS, with compliance based on 30

- day rolling averages. Although we have not set limits for fine particulate matter as the commenter requested , the final regulations for mercury , HCl and SO 2 will result in the co benefit of reducing fine particulate matter emissions. Comment : Several c ommenter s ( 64 , 73 , 74 , 83 ) expressed concerns over the proposed NSPS for PM of 0.086 lb/ton of clinker. Commenter 64 states that the proposed limit of 0.086 lb/ton of clinker i s not supported by the data available from new plants with the identified technology ; it does not allow for deterioration of performance over time ; and it does not allow for an adequate margin of compliance. Commenter s believes that EPA used insufficient data to develop the standard and failed to consider situations where gases from kilns, clinker coolers, and coal mills are combined for energy

recovery purposes. Commenter 73 has spoken to major suppliers of cement kiln systems and believes that baghouse te chnology with membrane bags is capable of achieving a continuous outlet grain loading rate of 0.010 gr/dscf. Appl ying EPA’s factors for standardized volumetric flow and feed

- to

- clinker ratio (54,000 dscf/ton of feed and 1.65 tons feed/ton clinker), an appropriate NSPS PM standard would be 0.127 lb/ton of clinker for cement kilns and clinker coolers. Commenter 73 and 74 also believes that when clinker cooler and kiln gases are combined, the standard for these s ys tems should be additive. The c ommenter s state d that the standards must be set at a level that recognizes that there will be some deterioration in performance over time. According to the commenter s , in most cases, emission rates achieved immediately after installation of pollution control equipment wi ll not be representative of the performance over the life of the source, as the bags and the baghouse itself age and experience normal wear, even with proper operation and maintenance. Commenter 73 agrees with EPA that “fabric filters control generally to the same concentration irrespective of the PM loading to the filter inlet, though some variability in PM emissions from fabric filters does occur due to seepage and leakage.” It is the seepage and leakage that becomes an issue as baghouses age. Commenter 6 4 states that the PM stack testing data used b y EPA in their anal ys es were obtained from kiln

- baghouse s ys tems that had operated for less than 5 years and therefore , EPA has not demonstrated that they have proposed a limit that new sources can sustain long term

. EPA has recognized this in numerous other rulemakings, including in setting emission standards for hazardous air pollutants at new cement kilns burning hazardous waste where they amended the PM limits for new sources in that NESHAP based on data dem onstrating that the original PM standard was “overl y stringent in that it does not fully reflect the variability

of the best performing source over time.” Response : For a discussion of issues raised by these commenters, see the preamble . See also section 2 .8.2 of the comment and respons e document for the final NESHAP. Comment : Commenter 64 submitted recent PM test data from 25 preheater and preheater/precalciner kilns consisting of 42 separate Method 5 tests. The data includes information on whether bags were membrane bags and whether the raw mill was on or off. The commenter evaluated the data and drew the following conclusions:

 The test results were not statistically normall y distributed.33

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

 Using the Mann Whitney test, the difference in the means for the bag ty pes was not statistically

significant.

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

 Based on a number of test results for three Florida kilns, there is substantial day

- to

- day variability

that must be considered in setting the NSPS.

 The upper 95% confidence interval for the test data is 0.108 lb/ton clinker which is approximately 0.01 gr/dscf (or 0.127 lb/ton clinker), the same as the achievable limit recommended b y cement design firms. Commenter 83 also supports a PM limit of 0.127 lb/ton clinker. Response : Indeveloping its final PM emission limits, EPA evaluated data submitted by the commenter along with data collected previously as well as data submitted following the proposal of the NESHAP amendments. Data submitted by the commenter appeared to contain kilns that were lower emitters than kilns in our original group of kilns; w e requested test run results for those kilns from the commenter. PM emissions limits were developed as MACT floor limits, which under the final rule, include limits for new kilns subject to the final NSPS as well . Under the MACT floor approach, the top performing kilns were selected based on the average of their emissions test results . We noted , as did the commenter, that PM emissions tend to be greater during mill off than mill on conditions. To determine a kiln ’ s ranking where we had tests under raw mill on and off conditions, we used weighted average emissions to account for the differences. For two top performing kilns, we had only a single test (three runs each); we requested additional data for those kilns and were able to add an additional six test runs for each of the two kilns . In addition, one commenter submitted additional test data for its kiln that wa s one of the top performers. From the 45 kilns for which we had adequate emissions data to evaluate, we identified the top 12 percent, or top 6 kiln s. Using a revised upper predi c tion limit (UPL) formula , we assessed the data variability to establish the MACT floor limits for existing and new kilns. The statistical method is further discussed in the preamble. Regarding the comment on the performance of membrane bags in comparison to standard bags, high efficiency

membrane filters under testing in EPA’s Environmental Technology Verification (ETV) Program, have on average significantl y outperformed non

- membrane depth filters in controlling PM and PM 2.5 as well as in other performance areas including average residual pressure drop and cleaning cycles. (World Cement, April 2007) Use of membrane bags is expected to reduce baghouse maintenance, extend bag life and reduce operational incidents such as increas ed opacity , and enable higher production levels. (W.L . Gore and Associates, Optimizing Kiln Operations by Improving Baghouse Performance, 2001)

. Comment : Commenter 73 believes that EPA may not have adequatel y quality controlled the data used in its anal ys e s. For example, the Lafarge Sugar Creek data used by EPA in their anal ys es came from a performance test that was done to demonstrate compliance with the PM 10 standard. Thus, this data is PM 10 , not PM.34

Response : As a result of this comment, the PM data in question was re

- examined. The Missouri Department of Natural Resources was contacted for clarification of the 2002 test data for the Lafarge kiln at Sugar Creek, MO. The initial testing to determine MACT compliance included testing for PM as well as PM 10 . The results used in our anal ys is were for PM and not PM 10 . The documents containing the results referred to here can be viewed in Docket No. EPA

- HQ

- OAR

2002

- 0051, docket items 2002

- 0051

- 2024 and 2002

- 0051

- 2039. Comment : One c ommenter ( 75 ) state d that the p roposed NSPS will require the use of baghouses equipped with membrane filters , which will present an additional capital cost over ty pical fabric filters in addition to an additional increase in maintenance over traditional filters, and that baghouse design s will be larger, increasing space requirements and energy consumption. Response : The commenter is correct that new baghouses may require the use of membrane filters to comply

with the NSPS PM limit and that the capital cost of these filters is greater th an conventional fabric filters. However, EPA disagrees with the other claims made b y the commenter. Because membrane bags utilize surface filtration rather than depth filtration of conventional fabrics, membrane bags require less aggressive cleaning, which greatl y prolongs bag life in comparison to conventional fabric, and operate at higher air

- to

- cloth ratios requiring, which would translate to smaller baghouse designs. Also, the trend in baghouses in the cement industry is to smaller pulse

-

jet baghouses. More importantly , under testing in EPA’s Environmental Technology Verification (ETV) Program, membrane filters have on average significantl y outperformed non

- membrane depth filters in controlling PM and PM 2.5 as well as in other performance areas including average residual pressure drop and cleaning cycles. (World Cement, April 2007) Use of membrane bags is expected to reduce baghouse maintenance, extend bag life and reduce operational incidents such as increased opacity , and enable higher production levels . (W.L . Gore and Associates, Optimizing Kiln Operations by Improving Baghouse Performance, 2001) . The other factor that will affect whether standard fabric filters are replaced with membrane filters is the increased use of ACI systems, including a polishing baghouse, to comply with the mercury emission limits under the NESHAP. EPA anticipates that ACI s ys tems will be placed downstream of existing PM control devices because of the inability to recycle CKD containing carbon from the ACI back to the kiln. Recycling CKD is a common practice in the industry . The result is that many kilns will be equipped with two PM control devices in series, in which case it is unlikely that standard fabric bags will need to be replaced with membrane bags in order to achieve compliance with the PM limit. Because new kilns will be subject to PM limits that were developed as part of developing the MACT floor limits under the NESHAP for portland cement manufacturing, costs incurred to compl y with the final PM limits are attributable to the NESHAP rather than the NSPS. Comment : Commenter 75 asks that EPA consider a grain loading limit of 0.01 gr/dscf as a more practical alternative to the lb/ton of feed limit noting that PM emissions limits are ty picall y based on grain loading (gr/dsc f) which is more representative measures of PM emissions, and is not dependent upon production rate. A gr/dscf limit would better reflect the actual efficiency of the control device, regardless of the production rate. Commenters75, 76 and 77 stated that m odern baghouses can consistentl y achieve a continuous outlet grain loading of 0.010 gr/dscf. Of course, this emission rate can onl y yi eld a lb of particulate/ton clinker value when converted using the site specific volumetric flow rate and35

feed

- to

- c1inker conversion factor. Here again, both values vary from site to site and must be evaluated on an individual basis. For that reason, the commenters would not suggest a lb of particulate/ton clinker PM limit; but a gr/dscf limit. Response : As discussed in the p reamble, EPA developed PM limits for existing (0. 0 4 lb/ton clinker) and new kilns (0. 0 1 lb/ton clinker) using the MACT floor approach; the PM limits for new kilns are also applicable to new kilns under the NSPS. Inresponse to the comment that the limit sh ould be set at 0.1 gr/dsc f , EPA anal yz ed the grain loading data for the MACT floor kilns to determine what the PM limit would be if we were to put the limit in units of gr/dscf. The average grain loading of the MACT floor kilns is 0.002 gr/dscf

. The MACT f

loor limit based on the UPLfor the se top performing kilns would be 0.004 gr/dscf, well below the commenter’s suggested 0.1 gr/dscf. In response to the commenter’s suggestion that EPA use gr/dscf as the format for the PM limit, EPA believes, as we stated in the preamble to the proposed rule, that an output

- based standard, i.e., lb/ton of clinker, promotes efficiency among the sources as opposed to input or concentration based standards

. An output based standard is also consistent with permit limits set by m any states that we reviewed. A disadvantage of the concentration standards is that emissions can increase as a result of the intentional or unintentional addition of dilution air to the exhaust gas stream which has the effect of reducing the concentration but not emissions. For these reasons EPA did not replace the output based standard with concentration based limit or offer one as an alternative to the output based limit. The PM data for the top performing kilns under the NESHAP resulted in a MACT floor l imit of 0.04 lb/ton of clinker for existing kilns and 0.01 lb/ton of clinker for new kilns. As required b y the CAA and subsequent court rulings, EPA is bound to establish limits of the top performers. Even considering the data of the top performing kilns in gr/dscf, the limit for existing kilns as described above is well below the commenters’ recommended 0.1 gr/dscf. 

### 4. 6 Opacity Comment : One c ommenter ( 64 ) agrees that there is no basis for revising the current NSPS standards that appl y to affected facilitie s at p ortland cement plants other than the cement kiln and the clinker cooler and states that they are not aware of data that would support imposing a limitation more stringent than the current 10 percent opacity standard. The Commenter 64 further states that an opacity standard below 10 percent could not be determined reliably due to the margin of error associated with the EPA Method 9. Commenter 83 urges EPA to maintain the existing subpart F opacity limits. Response : We are removing all opacity standards for kilns and clinker coolers because these sources will be required to monitor compliance with the PM emissions limits by more accurate means. Comment : One c ommenter ( 69 ) believes that all kiln stacks should be subject to a 20 percent opacity limit as is currently required in the existing p ortland cement plant NSPS. Kiln stack emissions have the potential to form a secondary (reactive) plume after the exhaust gases exit the stack. There have been instances where a certified in

- stack continuous opacity monitor (COM)36

read opacity

well below 20 percent while opacity observations of a certified Method 9 reader were in the 40

- 60 percent opacity range. The disparity between the COM readings and the Method 9 readings were attributed to exhaust gases reacting upon exit of the stack to form a secondary plume approximately

300

- 500 feet downwind of the stack exit. Commenter 69 supports the p roposed r

ule's requirements regarding kiln stack particulate monitoring using bag leak detection systems, electrostatic precipitator predictive models, and continuous emissions monitors. However, Commenter 69 does not support allowing facilities that use these particulate monitoring systems to be exempt from a kiln stack opacity limit. Response : See the previous response. 

### 4. 7 VOC an d CO Comment : One c ommenter ( 59 ) states that a co

- benefit of using SCR sy stem to control NO x emissions is that they

simultaneously

reduce VOC emissions and o rganic HAPs including dioxins, f urans, and ammonia. The commenter states that SCR removes greater than 80 percent CO, and greater than 70 percent of VOCs. Response : EPA agrees with the commenter that one of the advantages of SCR technology for NO x control is the co

- benefit of simultaneously reducing emissions of other pollutants, including VOC and poss ibl y CO. But as discussed earlier (see section 4.3), the limited application of SCR technology in the cement manufacturing industry (three kilns in Europe and none in the United States) and known potential for mechanical problems in operating the technology leaves EPA unconvinced that SCR qualifies as best demonstrated technology . As a result, the final emission limits for NO x are based on the use of well designed combustion sy stems in conjunction with SNCR technology , which has been demonstrated on numerou s kilns operating in the United States. Comment: C ommenter s ( 64 , 73 ) support EPA’s conclusion that revised NSPS for p ortland cement plants should not be expanded to include limitations for carbon monoxide or volatile organic compounds

. The c ommenter s agree that fuel

- efficiency considerations already

assure that CO emissions from incomplete fuel combustion are minimized. The c ommenter s also agrees that the THC limitation in the p ortland c ement NESHAP will assure that cement plants subject to the proposed Subpart F NSPS will not emit excessive levels of VOCs. Response : EPA acknowledges that the commenters are in agreement with EPA’s decision to not establish new source performance standards for VOC and CO. Comment : One c ommenter ( 71 ) believes that EPA should t ake this opportunity to also set appropriate VOC and CO emission li m its for cement kilns. Based on the testing conducted at a long dry cement kiln, the uncontrolled VOC and CO emission levels are in the range of 0.62

- 0.70 and 1.62

- 2.14 lb/ton of clinker, r espectivel y. These uncontrolled VOC and CO emission levels can be reduced once the appropriate control technologies are identified. Commenter 71 encourages EPA to further review available test data for cement kilns, identify appropriate control technologie s, and establish achievable limits.37

Response : As discussed in the final rule, n on - dioxin THC emissions, most of which are VOC, are being regulated under the final NESHAP amendments

. Under the final amendments to the NESHAP, THC limits of 24 ppm are being s et for existing and new sources, thus there is no need to establish new source performance standards for VOC. As described in the proposed rule, highly efficient combustors in precalciner kilns will minimize emissions of CO from burning fuel

. In cases where the organic content of the raw materials is high enough to emit high levels of CO, THC emissions will also be elevated and require that the facility take steps to comply

with the NESHAP limits for THC. Therefore, elevated CO levels that occur in conjunc tion with elevated THC levels will be controlled as part of a plant ’ s control of THC emissions. 

### 4.9 Fugitives Comment : One c ommenter ( 68 ) strongl y recommends that EPA promulgate NSPS for fugitive emissions from clinker storage piles, raw materials handling, and baghouse fall

- out from cement plants. These sources of fugitive emissions contain not only fine particulate emissions, which pose substantial harmful effects to public health, but a number of inorganic hazardous air pollutants, such as arsenic, mercury and hexavalent chromium. The commenter cites a recent California study

indicates that high levels of hexavalent chromium, in particular, are emanating from p ortland cement facilities

. Specifically , storage piles of clinker should be either partially or , preferabl y, full y enclosed; installation of wind screens should be considered; and other corrective work practice measures evaluated and promulgated. Response : See the preamble for a discussion of actions that EPA is taking regarding fugitive emissions f

rom handling and storage piles. 

### 4.10 Overall Achievability Comment : One c ommenter ( 64 ) has concerns about the overall achievability and cost effectiveness of the proposed NSPS. First, it does not appear EPA has given sufficient consideration to whether each of the individual proposed emission limitations can be achieved, or achieved at reasonable cost, at the same time as other proposed NSPS emission limitations and other applicable emission limitations. EPA has not identified any cement plants that employ the combination of measures to achieve very low PM emissions, NO x reductions, and SO 2 reductions that form the basis for the proposed NSPS. Commenter 64 urges EPA to give additional consideration to these interactions that may occur when the various contro l technologies identified in the proposed NSPS are employed together. One c ommenter ( 77 ) understands the newly proposed NSPS limits for SO 2 , NO x and PM may be achievable in a large number of projects

. Commenter 77 also states that these new limits would n ot be achievable for all projects as would be required by these new NSPS limits. Current cement plant process technology and equipment are very

effective at minimizing the potential air pollutant emissions through state of the art combustion technology and add on pollution control sy stems. Each plant has specific raw materials and fuels which combine to make a variety of cement types. All of these factors combined influence the potential emissions of SO x , NO x , CO38

and PM. Detailed anal ys is and proper application of various technologies are required for each different combination of plant specific materials. Response : EPA is mindful that it must set standards that reflect achieved performance, that process inputs (raw materials and fuels) must be accounted for in ascertaining sources’ performance, and that costs be considered b y EPA in ascertaining the level of the BDT. In considering achievability, EPA established limits based on what best performers actually achieved. EPA has carefully developed data for each standard, assessing both process performance and technological controls in doing so. For example, while EPA has set its limits for NO x based on the use of low NO x processes and SNCR, it has rejected more stringent limits based on SCR control technology th at we do not consider to be a clearl y established NO x control technology

in the cement industry . EPA has also adopted 30

- day averaging periods for all of the standards, further allowing short term fluctuations to be averaged out over the 30

- day period. The result are limits that reasonabl y estimate the performance over time of the best demonstrated technology

. Itis true that many sources will need to install controls to meet these standards, and that these controls have significant costs. This is part of the expected process where, b y definition, new sources will need to perform at levels above what is achievable b y most existing sources. The Agency

believes that it has utilized best efforts to follow the statute and applicable caselaw, and has not adopted standards which are impermissibly unachievable.39 

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

can include less than 24 operating hours. Response : A definition of operating day s has been added to the rule. A kiln operating day can include less than 24 operating hours. Comment : One c ommenter ( 57 ) states that EPA should consider allowin g sources that have NO x , SO 2 , or stack flow CEMS certified and operated per 40CFR75 to use those CEMS to meet the monitoring requirements. There are examples of this in 60.49Da(b)(4) and 60.49Da(c)(2). Response : We agree that CEMS certified and operated pe r 40CFR75 could be used to me et the monitoring requirements; an owner/operator can request alternative monitoring in such a situation. 

### 5.1 SO 2 Comment: One c ommenter ( 64 ) states that with regard to SO 2 monitoring, EPA has not provided adequate explanation of how monitoring data would be used to determine compliance with the percent reduction option in the proposed SO 2 standard, both for wet scrubbers and for facilities that can compl y using alkali injection. In addition, because EPA asserts that 80 percent of cement plants subject to the proposed NSPS will not need any add

- on controls to meet the proposed standard, because they have low or moderate sulfur content in their raw materials, and the nature of those raw materials is relativel y stable, there is no justification for imposing the added capital and operating cost of continuously monitoring SO 2 emissions. Commenter 64 suggests that cement plant operators relying on low

- sulfur raw materials and inherent SO 2 reduction in the process should have the option of conducting an initial performance test for SO 2 , with retesting at least once every five years, with no continuous monitoring of SO 2 required so long as the stack test shows SO 2 emissions less than 1.0 lb/ton. Response : The SO 2 compliance option of demo nstrating a 90 percent reduction was intended to apply to situations in which a wet scrubber is being used for compliance. In those instances, the owner or operator may

comply with either the SO 3 emission limit or the 90 percent reduction. The 90 percent reduction is determined my continuously

measuring SO 2 at the inlet to the scrubber and at the scrubber outlet. If a facility is using alkali injection, compliance is demonstrated b y meeting the SO 2 emission limit of 1.33 lb/ton. The final rule has been revi sed to make this clear. In response to the commenter’s suggestion that there is no need for SO 2 monitoring where scrubbers are not needed for SO 2 control, it is possible that a source might change a raw material40

and significantly

increase SO 2 emissions beyond the standard. If monitoring is not in place, these excess emissions could be unchecked for five ye ars before they were discovered. We believe the c ost of the SO 2 monitor is reasonable to prevent these excess emissions. These monitors are well establish ed technology

that are already

installed on over 30 cement kilns, including those without SO 2 controls. Comment : One c ommenter ( 68 ) strongl y supports the requirements proposed by EPA for continuous emissions monitoring for both SO 2 and NO x to assure compli ance with a pplicable emissions limits. Response : EPA acknowledges the commenter’s support

. 

### 5.2 PM Comment : One commenter (83) recommends eliminating the requirement for PM CEM monitoring stating that the technology is neither sufficientl y advanced nor reli able. Response : EPA disagrees with the commenter’s assertion that PM CEM is not sufficiently advanced or reliable. It is currentl y required in other rules for the monitoring of PM emissions and is used in Europe

. EPA is replacing bag leak detectors and opacity monitoring and requiring the use of PM CEMS to monitor PM emissions from all kilns and clinker coolers. 

### 5.3 Opacity Comment : One c ommenter ( 67 ) states that in the proposed changes to §60.62(a)(2) and (b)(2), EPA proposes to exempt kilns and clinker c oolers, with an applicability date prior to June 16, 2008, that use a baghouse leak detection (BDL) sy stem, electrostatic precipitator (ESP) predictive model, or a PM continuous emissions monitoring sy stem (CEM) from opacity standards. We have the following concerns : (1) The kilns and clinker coolers would not have an opacity standard per the NSPS if they have a PM monitoring s ystem as an alternative to the COMS or daily Method 9 readings. Although the language in §60.62(d) indicates an intent by EPA to require the owner or operator of the affected facility to compl y with the more stringent of two different requirements, the proposed language refers to “another regulation in title 40 of this chapter.” Many states have a 20 percent maximum opacity standard in the ir state implementation plan (SIP) requirements. This could mean a relaxation of the opacity standard for the clinker coolers from 10 percent (current NSPS standard) to 20 percent standard. (2) If the PM monitoring s ys tem is not operating or is operating incor rectl y, then opacity may exceed the opacity

limit (20 percent or 10 percent as applicable) in the short term. The current opacity limit is for all of the time the kiln or clinker cooler is operational on or after the date the performance test is conducted per 40 CFR 60.8. (3) The proposed language in §60.62(a)(2) and (b)(2) only exempts kilns and clinker coolers from opacity limits if their applicability date was before June 16, 2008. Therefore, the41

newer kilns and clinker coolers (applicability date after June 16, 2008) would be subject to the opacity

standards. The monitoring requirements for the newer units in §60.63(b)(2) includes the alternative PM monitoring options, but doesn’t include a COMS. (4) Requirement §60.64(b)(6) in the proposal states that any unit subject to the 10 percent opacity limit must comply

with §63.1350. The clinker coolers with applicability date after June 16, 2008 would be subject to the 10 percent opacity limit in §60.62(b)(2). Requirement §63.1350 requires a COMS to be installed or mus t conduct daily Method 9 tests (for multiple stacks only). Commenter 67 suggest s EPA consider removing the exemptions in §§60.62(a)(2) and (b)(2) and retaining the opacity limits. Requirements in §60.63(b) {PM requirements} and (c) {multiple stacks alternative to COMS} allow for the alternative PM monitoring methods. If the exemption remains, we suggest changing language in §60.62(a)(2) from "(a)(1)(i)" to "(a)(1)" and changing language in §60.62(b)(2) from (b)(1)(i) to (b)(1) , so that it is consistent on which units are subject to the opacity limits. Response : Inthe final rule, PM CEMS are required in place of bag leak detectors and/or opacity monitoring on all kilns and clinker coolers. Comment : One c ommenter ( 73 ) agrees with EPA that opacity monitoring f

or a kiln or clinker cooler subject to the proposed NSPS is unnecessary if PM CEMS or bag leak detectors (BLD) are installed. Further, Commenter 73 supports EPA’s decision not to require PM CEMS, but make it an option to BLD technology

. Commenter 73 also s upports compliance testing for PM on an every

five year basis. Response : See the previous response. 

### 5.4 CEMS Comment : One c ommenter ( 63 ) supports the proposal to allow facilities to install PM CEMS as there are several types of emissions measuring techniqu es that can be applied to combustion processes. The commenter identifies different PM CEMS technologies and their costs. Response : See the previous response. Comment : One c ommenter ( 64 ) agrees that PM CEMS should be an option, not a requirement, and that opacity monitoring is not necessary for a kiln or clinker cooler that employs a PM CEMS or baghouse leak detectors or parametric monitoring of an ESP. Commenter 64 also agrees that compliance testing every five ye ars is adequate in light of the continuous m onitoring requirements. The commenter also support s the alternative in proposed section 60.63(c) for daily visual opacity

monitoring for control equipment with multiple stacks. Commenter 64 supports as well EPA’s proposal that sources subject to the current NSPS should have the option of installing baghouse leak detectors or PM CEMS as an alternative to continuous opacity monitoring (COMS). Commenter 64 states that i t is not clear from the wording of proposed section 60.63(b ) if sources choosing to install a PM CEMS need not also install and maintain baghouse leak detectors.42

Commenter 64 recommends that EPA continue to allow COMS as a monitoring method, so that a kiln or clinker cooler subject to the revised NSPS would have the option of monitoring complianc e with a COMS, a PM CEMS, or baghouse leak detectors. The commenter states that EPA’s justification is an insufficient basis for excluding a proven monitoring technique, which cement manufacturers already know how to operate and maintain and which will cos t less to install and maintain. Response : See the previous response. 

### 5.5 Clinker Production Comment : C ommenter s ( 64 and 73 ) stated concerns about the requirement to continuously monitor clinker output. The commenters are not aware of existing weigh scale s ys tems currently in use to measure clinker exiting the kiln or clinker cooler. According to the commenters, clinker exiting the kiln and the clinker cooler is extremel y hot and cannot be transported to storage b y conventional belt conveyor systems. Because drag and screw conveyance systems that are used are not designed to incorporate weigh scale s ys tems, a large majority of cement plants measure clinker production b y using a raw mix weigh scale system on the conventional belt conveyor sy stem feeding the ki ln, and then appl ying a standard feed

- to

- clinker conversion factor. Inthe py roprocessing s ys tem, feed

- to

- clinker conversion is very constant which is especiall y the case for PH/PC kilns. EPA should provide that as an alternative to the requirement to install a clinker weigh scale s ys tem. The provision for approval of an alternative monitoring method is a cumbersome and time

- consuming approach that in practice will not be a practical substitute for basing clinker output measurement on the demonstrated techn ology of weighing raw materials and appl ying a conversion factor). The commenter included suggested regulatory language

. Response : We explicitly

state in the NESHAP that a sy stem that directl y monitors feed rate and uses a conversion factor to determine th e clinker production rate is an acceptable method of monitoring clinker production rates. The final rule language for the NSPS likewise makes this clear

.43 

### 6 Test Methods and Procedures Comment : According to o ne c ommenter ( 67 ) the statement in §60.64(b)(5), “kiln (including any associated alkali by

pass and clinker cooler)” shall be tested every 5 years could be interpreted that only clinker coolers associated with kilns subject to Subpart F have to be tested every five ye ars. Commenter 67 suggest s EPA revise the language to state “kiln (including any associated alkali by pass) and clinker cooler , ” which identifies the intention that each kiln and clinker cooler has to be tested every

5 years. The 5

- ye ar testing requirement is for PM emissions only . There are n o NO x and SO 2 testing requirements. This could be interpreted that the kilns or clinker coolers with a PM CEMS must also conduct separate performance tests every 5 years in addition to the annual relative accuracy tests that are required for the CEMS. If i t is EPA’s intent to require PM performance testing every 5 years despite a PM CEMS, then it could be interpreted that the PM CEMS is less accurate or reliable than the NO x or SO 2 CEMS. If the annual relative accuracy tests for the PM CEMS are equivalent to the 5

- ye ar testing, then we suggest an exemption for kilns or clinker coolers with a PM CEMS. I f the annual relative accuracy tests for the CEMS are not equivalent to periodic performance testing, then we suggest a periodic (5

- ye ar) performance testing f

or NO x and SO 2 should be added for the kilns which had commenced construction, modification, or reconstruction after June 16, 2008. Response : The identified section of the rule will be revised in light of the final requirement that PM CEMS be used to monit or emissions from all kilns and clinker coolers, Comment : One c ommenter ( 67 ) states that § 60.64(b)(6) would require units subject to the 10 percent opacity limit to comply with §63.1350. The specific parts of the §63.1350 that these units are subject to s hould be identified, because not all of the NESHAP requirements apply to these units. Response : The specific sections of §63.1350 that apply have been added to the rule (now at 60.64(b)(4)) as suggested.44 

### 7 Impacts 7.1 Cost and Cost Effectiveness Comment : One c ommenter ( 59 ) states that there was a high degree of consistency between the three independent assessments of SCR cost effectiveness. The U.S. EPA median value of $1 , 800/ton NO x was well within the range presented in the EU IPPC document, $1 , 500 to $ 3 , 800 per ton, and also was close to the value estimated by the blue ribbon panel for dry cement kilns of $2 , 000 per ton. The blue ribbon panel also estimated the cost effectiveness for a series of smaller older wet kilns at $5 , 800/ton NO x . One c ommenter ( 63 ) states that the cost effectiveness of SNCR deployed on a PH/C cement kiln is $700 ton/ NO x removed. Inthe evaluation of SCR’s cost effectiveness in removing NO x from a cement kiln a conservative threshold ranges from $1,800

- $5,000 per ton of NO x controlled. One commenter (60) states that according to the Swedish environmental agency “the total cost (of SNCR) with depreciation, capital cost, energy and ammonia related to NO x abated was is approximately

$325/ton of NO x removed. The commenter included the report from the Swedish report as well as other reports on the performance of SNCR as attachments to the comment. The commenter cites an example where the SNCR is operated to achieve a reduction from 6 to 1 lb NO x/ton, the cost effectiveness would be l ess than $700/ton NO x removed. Commenter 60 cites European cost comparisons of SNCR and SCR that show a cost effectiveness for SNCR of $465/ton of NO x removed and $1,230/ton of NO x removed for SCR assuming a conversion of $1.30/ €

. Response : The EPA general ly agrees with the commenter on the range of cost effectiveness for SNCR and SCR. We consider SNCR to be BDT for NO x control. The final NO x limits are based on the expected performance of SNCR (and proper control upstream of the end

- of

- stack SNCR) and we b elieve it can and will be used to meet the final limit for NO x . While we see SCR as a promising technology

for NO x emission control, we have not set emission limits based on SCR technology for reasons stated in the preamble to the final rule and other comm ent responses

. We will continue to monitor progress in the control of NO x emissions from the cement kilns and will reconsider SCR at the appropriate time. Comment : One c ommenter ( 64 ) state d that the proposed PM limit would have the effect of requiring modi fied or reconstructed cement plants using an ESP to replace it with a fabric filter using membrane bags and that EPA has simply ignored costs impacts for modified facilities that will have to replace an ESP with a baghouse

. Response : Inthe final rule, the PM limits established under the NESHAP apply to both new and existing sources. So regardless of whether a kiln is modified/reconstructed or not, it will be subject to the revised PM emission limits. In estimating the impacts of the more stringent PM limit s under the NESHAP , we did evaluate kilns that were currently controlled by ESP to determine the costs for such kilns. Inaddition, it is not clear that kilns equipped with an ESP must necessaril y remove them to meet the NESHAP/NSPS PM standard. We believe that most kilns will have to install an activated carbon injection system with a polishing baghouse in order45

to comply

with either the mercury

emission limits or limits for organic HAP. As a result, it is likely that a kiln currently

equipped with an ESP will be adding a baghouse (as part of the ACI sy stem) downstream of the ESP and will be able to meet the final PM limit without replacing the ESP

. Comment : One c ommenter ( 64 ) also believes that the cost

- effectiveness discussion does not reflect adequate co nsideration of the costs of achieving the emission reduction required b y the proposed standards as mandated b y CAA section 111(a)(1). Commenter 64 does not believe that simply comparing the costs per ton of pollutant removed to the costs per ton that has b een imposed in NSPS for the electric utility represents an adequate weighing of the costs involved. Even based on EPA’s cost estimates, the proposed NSPS would impose millions of dollars of additional costs on each new or reconstructed or modified kiln, an d tens of millions of dollars for each kiln required to install a wet scrubber. These costs should be considered as well in conjunction with costs already imposed b y the p ortland cement NESHAP and the additional costs that may

be imposed as a result of the ongoing review of that NESHAP. These are costs not borne b y the industry’s competitors in Canada and Mexico and elsewhere. EPA needs to provide better justification that these costs are justified by the differences between the current Subpart F NSPS and the proposed Subpart F NSPS. Response : The MACT emission limits for PM will apply to existing and new kilns and will be applicable to kilns subject to the NSPS. We have considered the costs of controls under both the NSPS and the NESHAP as well as the econo mic impacts associated with those costs. See the preamble for a discussion of the costs, economic impacts and benefits of the final amendments. Comment : One c ommenter ( 75 ) states that the “uncontrolled” inherent emissions of SO 2 considered b y EPA as repres entative of modern kilns are too high, thereb y incorrectly making wet scrubbing cost effective. EPA has used those sites currentl y operating wet scrubbers as the basis for establishing “high levels ” of uncontrolled sulfur emissions. However, this is inappropriate because it ignores fundamental technological differences between various cement kilns. The commenter states that in one case, EPA used data from a facility where the scrubbers are controlling emissions from wet kilns, not modern preheater/precalc in er kilns. The other high

sulfur facility that is referenced b y EPA does not represent a new kiln. Rather, that project reflects the addition of a preheater/precal ciner to an existing kiln. In addition, the uncontrolled SO 2 emissions for this kiln approximated at 13 lb/ton includes approximately 8 lb/ton from the alkali by pass stack and 4 lb/ton from the main stack. Modem kilns with high sulfur raw materials can achieve inherent emissions on the order of 4.5 lb/ton. When the inherent emissions rate of new ki lns is considered, wet scrubbing is not cost effective or environmentally beneficial and should not be considered BDT

. Response : Because of the requirements for HCl control on existing and new kilns under the NESHAP, most kilns will be equipped with wet sc rubbers or lime injection for the control of HCl. As a result, new kilns subject to the revised NSPS will have their SO 2 emissions incidentally

controlled. None of the cost of the scrubbers will be attributable to the final NSPS amendments. The commenter i s taking issue with the uncontrolled SO 2 emission levels we used in estimating the impacts of the proposed standard. Although the cost of controlling SO 2 is attributable to the46

NESHAP, we note that in the final anal ys is of impacts under the NESHAP, we did revise the uncontrolled SO 2 emissions to reflect the variation in SO 2 emissions due to kiln ty pe and location. In order to examine the effects of kiln ty pe, fuel and raw materials on SO 2 emission, average SO 2 emission were estimated from 2002 National Emis sions Inventory data in the Cap+Trade workboo k for each market b y kiln type (Andover, September 23, 2008). Generall y, preheater and precalciner kilns had the lowest SO 2 emission rates while wet and long dry kilns generall y had the highest SO 2 emission when comparing different locations. Location was determined to play

a significant role in SO 2 emissions from kilns. Both mean and median emissions were examined. Because median values tend to be less impacted by outliers than means, median SO 2 emission rates w ere used in the final anal ys is of air quality impacts. 

### 7.2 Environmental and Energy Comment : One c ommenter ( 75 ) states that the economic and environmental impacts of wet scrubbing are understated. EPA estimated the cost effectiveness for reducing high uncontrolled SO 2 emissions as less than $1,000 per ton of SO 2 removed. However, if the uncontrolled emission rate is corrected to a more appropriate rate, the cost per ton increases due to two effects. First, a lower uncontrolled emission rate results in less SO 2 being removed, increasing the cost of removal per ton of emissions. In addition, as the amount of SO 2 controlled is reduced, the amount of sy

nthetic gy psum available , and the gypsum credit, is reduced. The commenter states that they believe that the credit for the use of scrubber derived gy psum used by

EPA is too great. Cement always includes gy psum at levels of around 5 percent by mass as a setting retarder. The commenter estimate d that the maximum quantity of gy psum recycled will be 23,342 tons/year, which is well below the 84,101 tons/year listed in the example. Correcting this error further reduces the cost effectiveness of wet scrubbing. The commenter states that a wet scrubber would greatl y increase the amount of water used b y a cement facility . The Southeast has experienced frequent drought conditions in recent years restricting the amount of water available for both residential and industrial use. Legal proceedings have also taken place between Southern States over the right to use water. The requirement of a wet scrubber to control SO 2 would create additional stresses over this water resource since an estimated 45,000,000 additional gallons per year of fresh makeup water would still be required even with recycling and treatment. Response : Because of the requirements for HCl control on existing and new kilns under the NESHAP, most kilns will be equipped with wet scrubbers or lime injection for the control of HCl. As a result, new kilns subject to the revised NSPS will have their SO 2 emissions incidentally

controlled. None of the cost of the scrubbers will be attributable to the final NSPS amendments. Even in the absence of the NESHAP, EPA considers wet scrubbers and lime injection to be BDT and justified for the control of SO 2 emissions. Estimates o f scrubber costs under the final NESHAP were based on a review of various reported capital costs , fixed costs and variable costs for limestone, water, power and gy psum (Andover, March 10, 2009). Based on comments received on the costing methodology , cost f actors were revised which resulted in an increase in estimated scrubber costs. In particular, gas flowrates and capital cost estimates were found to underestimate costs. As a result, gas flowrates were adjusted, along with other factors dependent on gas fl ow rates, for example water usage, with the47

result that estimates of capital costs were substantially increased (Andover, September 25, 2008; Andover, March 10, 2009; Andover, February 26, 2010; Andover, May 6, 2010). Regarding the commenter ’ s concern ove r insufficient water availability for scrubbers, other options for reducing SO 2 emissions include dry lime injection as well as utilizing fuels and feed materials with low sulfur content to the extent practical. Comment : One c ommenter ( 75 ) states that the energy impacts of wet scrubbing are significant. In EPA’s scrubber cost analysis, the power requirement for a typical scrubber on a 1,200,000 tons/year plant is over 1,500 kW, or 10 kWh/ton of clinker

. This additional electricity demand rep resents not less than a 20 percent increase over the power required for clinker production in a modem cement kiln (around 50 kWh/ton of clinker). Additionall y, this will lead to the formation of an additional 8,850 tons per year of carbon dioxide. Response : EPA is aware o f the increased energy demand associated with the additional control that will be installed as well as the increase in CO 2 emissions that will result from the increase in energy demand. These were estimated as part of the anal ys is of the impacts associated with the final rules. Comment : One c ommenter ( 75 ) states that the proposed SO 2 limit would require wet scrubbing at more facilities than the one in five estimated b y EPA

. A review of the RBLC shows five kilns with permitted limits above the proposed NSPS limit, which would require wet scrubbers under the proposed rule . EPA also asserts that most new kilns will be located at sites with low sulfur content in limestone or at greenfield sites but offers no data to support this claim. In reality, a company fac es significant hurdles to opening new plants and quarries at greenfield sites. By overlooking reconstructed or modified kilns at existing sites with higher levels of sulfur, EPA will be subjecting a greater number of kilns to wet scrubbing in o rder to meet the proposed limit leading to significantly

greater economic, environmental, and energy impacts. Commenter 75 states that the value chosen to represent moderate uncontrolled SO 2 emissions, 1.3 lb/ton of clinker, is based on an average of data points coll ected no more recently than 1996. While EPA has not provided back up for these data in the rulemaking docket for this rule, the commenter states that it is reasonable to expect that if the average value is 1.3 lb/ton, a number of the data points would fall above this value and the proposed limit of 1.33 lb/ton. Although EPA has indicated that the facilities with moderate uncontrolled emissions would not need controls, it is likely

that a number of sources in the “moderate ” category would require controls. This is reinforced b y the RBL C review, which shows a larger than expected number of kilns above the proposed limit. EPA indicates that the proposed limit was set to ensure that kilns with high uncontrolled SO 2 emissions meet the ty pical standard of BDT . How ever, the commenter believes that EPA based the proposed limit on data that are not representative of new, modem kilns, and thus the record misstates the costs and impacts of the proposed limit. I f EPA intended to target only

those facilities with high unc ontrolled SO 2 emissions, and not the facilities with moderate emission levels, the commenter suggests that EPA establish the new limit at the upper bound of the source group with moderate uncontrolled emissions. An SO 2 emission limit of approximately

4 lb/ton would still require that facilities with uncontrolled emissions at 13 lb/ton install wet scrubbing, while not imposing the economic, environmental, and energy burdens on facilities with moderate uncontrolled emissions. The moderate emissions group of p lants would48

have to install dry

lime injection. An NSPS limit of 4 lb/ton will allow other new kilns similar to those listed in the RBL C to meet the NSPS with dry lime injection, recognizing that those units are sti ll likely

to go through a BACT or LAER review that could result in a tighter limit on a case by case basis. Response : As discussed in a response to a previous comment, we have estimated that most existing and new kilns will install wet scrubbers or dry lime injection s ys tems in order to comply wi th the HCl emission l imits in the final NESHAP. We have revised our estimates of uncontrolled SO 2 emissions based on kiln ty pe and location. These impacts are summarized in the preamble. 

### 7.3 Economic Comment : One c ommenter ( 64 ) objects to EPA’s assumption that the proposed amendments to the NSPS would have little or no economic impact because of controls that will be required any way under state requirements, including BACT or LAER requirements resulting from NSR

. Because of the definitions of “modification” and “reconstruction” as applied to NSPS, a cement manufacturing facility

may be considered “modified” or “reconstructed,” and therefore subject to the revised NSPS, even when the activity that constitutes a “modification” or “reconstruction” results in li ttle or no increase in actual emissions. Under these circumstances, state regulations may not impose any

particular control technology requirement (such as BACT ), and state permitting authorities may not require (and may not even have authority

to require) emission limitations that would be equivalent to the proposed amended Subpart F limitations. Response : As explained in the preamble and in other comment responses, cement kilns may adopt measures so that their hourl y emissions of the NSPS pollutants do n ot increase, so that such kilns are not “modified”. In light of these available measures, EPA is not adopting separate NSPS for modified kilns. Comment : Commenter 64 states that EPA is proposing to establish PM emission limitations that are at the margin o f the performance of the identified technology at existing best performer cement plants which will require new and modified cement plants to install even more efficient control technology

than that in use at plants subject to the current NSPS. EPA should evaluate the costs and emission reduction benefits of those proposed PM emission limitations, rather than just incorrectl y assuming the costs away. Response : As noted in other responses, EPA does not believe there are any costs under the NSPS for meeting th e PM standard, since new kilns will be required to meet the same standard under the NESHAP. Modified kilns are subject to the PM limits under the NESHAP . We have estimated that few kilns will install additional controls just for PM but are likely to reduce their PM emissions as a result of other controls necessary under the NESHAP. Comment : Commenter 64 states that there are numerous specific costs that EPA has ignored or assumed away

and that could constitute a significant additional cost burden. For examp le, EPA has not given adequate consideration to disposal costs for the scrubber sludge, scrubber wastewater (blowdown), and additional cement kiln dust that would be produced as a result of the proposed NSPS. EPA has not paid sufficient consideration to ammonia costs, either, which49

have risen dramaticall y i n the past year and can be expected to continue to rise. The commenter attached details on these additional cost considerations which EPA must take into account. Response : See impacts section of preamble of final rule. 

### 7.4 Multipollutant Comment : Several c ommenter ( 59 , 60, 63 ) state that the full

- scale SCR installations on cement kilns in Europe and the experience with SCR worldwide on coal

- fired power plants, incinerators, and other facilities have demons trated the ability of SCR to greatl y reduce NO x emissions and to simultaneously

reduce emissions of other pollutants, including many highly toxic ones. In addition to NO x reduction capabilities, there are a number of emission reduction co

- benefits associat ed with the installation of SCR, including : (1) Destruction of the other pollutants , e.g. , ozone inducing VOCs; (2) Reduction of air toxics such as dioxin and furan and benzene; (3) Facilitating the removal of mercury (Hg) by cataly tic oxidation; and (4) Minimization of f

ormation of fine PM by NO x and ammonia control

. Response: EPA is aware of and agrees with the commenters that there are Multipollutant benefits associated with the use of SCR in addition to the control of NO x . But as explained in previous responses, at thi s time EPA does not consider SCR to be adequately demonstrated for US portland cement kilns.50 

### 8 Miscellaneous 8.1 Proposed Rule Comment : One c ommenter ( 56 ) states that the NSPS is not fair to cement plant employees and will negativel y affect pay raises

. Re sponse : As part of our anal ys is of econo mic impacts, we are aware that certain marginal cement plants may

choose to shut down some kilns rather than spend the money to upgrade them. Comment : One c ommenter ( 66 ) states that the NSPS is well reasoned. The te chnology proposed ( SO 2 for scrubbers, fabric filters with membrane filters for PM, and SNCR for NO x ) are proven and available. The option for CEM for PM makes sense. Changing the standards to per ton of clinker also makes sense, so companies that are ineff icient in their material use are not rewarded. Response : EPA acknowledges the comment. Comment : One c ommenter ( 67 ) states that in §60.62(d) and §63.1356 {NESHAP Subpart LLL

- Portland Cement Manufacturing}: The proposed language states that if a pollutant is subject to emission limits or requirements that the most stringent requirement in Title 40 must be complied with, and the source is exempt from the less stringent requirement in Title 40. This requirement appears to be aim at an overlap of requirements between NSPS Subpart F and NESHAP Subpart LLL. The PM and opacity requirements in NESHAP Subpart LLL (for existing units only) are identical to the PM and opacity requirements for units currently subject to NSPS Subpart F. The commenter understand s the int ent to ensure adequate environmental protection while not overlooking inconsistencies between rules; however, if there are requirements which are different between the rules, then the rules should specificall y identify which requirement should be used. By identifying the rule which supersedes the other, EPA provides clarity and consistency

to state/local agencies and the regulated industry

. Response : In dicating that the most stringent provision must be complied with is the most efficient and direct way

to address this issue. Comment : One c ommenter ( 67 ) states that in §60.63(b)(2)(ii), (n), (n)(1), and (n)(5) {ESP monitoring}, the proposed language references "paragraph (o)". There is no paragraph (o) in this section of the subpart. The references should be c hanged from "(o)" to "(n)

. " In §60.63(c), the language should change from "modified on or before June 16, 2008" to "m odified after August 17, 1971 , but on or before June 16, 2008

. " It could be interpreted as requirements for units that commence constructio n or were reconstructed or modified prior to August 17, 1971. This language change would be consistent with the language proposed in other requirements in this subpart. Response : The provisions regarding ESP monitoring no longer appl y . Comment : One c omment er ( 70 ) states that the vacated Clean Air Mercury Rule (CAMR) has had a significant impact on our ability to reduce mercury

emissions expeditiously

and we now51

must wait on a m aximum achievable c ontrol t echnology (MACT) standard for existing coal fired util ity boilers. Commenter 70 urges EPA to address mercury emissions from cement kilns now by adopting a sufficiently

restrictive MACT standard for these units as part of its pending p ortland cement reconsideration. Response : EPA is promulgating amendments to its NESHAP for portland cement manufacturing facilities that will greatl y reduce mercury emissions. Comment : One c ommenter ( 70 ) states that many areas in the United States are struggling to comply with the National Ambient Air Quality Standards for ozone and fine particulate matter ( PM 2.5 ). All proposals for NSPS should be reflective of what appropriate controls can be implemented to minimize these pollutants or their precursors. Response : The final amendments to the NSPS and NESHAP will reduce PM 2.5 emiss ions although the extent of the reduction is not known. Comment : One c ommenter ( 81 ) states that it seems that the draft language of the proposed standards for new kilns and clinker coolers under § 60.62 (a) (2) and (b) (2) may not be clear with respect to indicating the that the opacity standard would not be applicable for new kilns and clinker coolers constructed, reconstructed, or modified after the date of publication of the proposed rule in the Federal Register. Commenter 81 reads these sections, as prop osed, as continuing to require the opacity standards except for kilns or clinker coolers constructed, reconstructed or modified after August 17, 1971 , but on or before the date of publication of the proposed rule in the Federal Register that use a bag leak detection system, ESP predictive model, or a PM continuous emission monitoring sy stem. Response : EPA is requiring the use of PM CEM S on all kilns and clinker coolers and is omitting the opacity requirements for these sources. 

### 8.2 Technical Support Documen t Comment : One c ommenter ( 60 ) further examined the “Technical Support Document for Portland Cement New Source Performance Standards Review” prepared b y EPA and posted in the Cement NSPS docket as Document No. EPA

–HQ

–OAR

–2007

–0877

- 0049. Commenter 60 is interested in this document because much of the information contained therein was derived from Department responses to EPA and contractor inquiries. The commenter recommended additional caveats and amendments , including more recent stack test results and continuous emissions monitoring system (CEMS) data and European experience with SCRs, will further support EPA’s proposed NO x limit. Response : All documentation that was used in the development of the final regulation s will be posted in the rulemaking dockets for the NSPS and the NESHAP. However, they may not all be contained within a single technical support document.