National Emission Standards for Hazardous Air Pollutants From the Portland Cement Manufacturing Industry and Standards of Performance for Portland Cement Plants

Federal RegisterSep 9, 2010

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 60 and 63

[EPA-HQ-OAR-2002-0051; EPA-HQ-OAR-2007-0877; FRL-9189-2]

RIN 2060-AO15, 2060-AO42

National Emission Standards for Hazardous Air Pollutants From the Portland Cement Manufacturing Industry and Standards of Performance for Portland Cement Plants

AGENCY:

Environmental Protection Agency (EPA).

ACTION:

Final rule.

SUMMARY:

EPA is finalizing amendments to the National Emission Standards for Hazardous Air Pollutants (NESHAP) from the Portland Cement Manufacturing Industry and to the New Source Performance Standards (NSPS) for Portland Cement Plants.

The final amendments to the NESHAP add or revise, as applicable, emission limits for mercury, total hydrocarbons (THC), and particulate matter (PM) from new and existing kilns located at major and area sources, and for hydrochloric acid (HCl) from new and existing kilns located at major sources. The standards for new kilns apply to facilities that commence construction, modification, or reconstruction after May 6, 2009.

The final amendments to the NSPS add or revise, as applicable, emission limits for PM, opacity, nitrogen oxides (NO

), and sulfur dioxide (SO

) for facilities that commence construction, modification, or reconstruction after June 16, 2008. The final rule also includes additional testing and monitoring requirements for affected sources.

DATES:

These final rules are effective on November 8, 2010. The incorporation by reference of certain publications listed in this rule is approved by the Director of the

Federal Register

on November 8, 2010.

ADDRESSES:

EPA has established two separate dockets for these actions: Docket ID No. EPA-HQ-OAR-2007-0877 for the amendments to the NSPS and Docket ID No. EPA-HQ-OAR-2002-0051 for the amendments to the NESHAP. All documents in the two dockets are listed in the

http://www.regulations.gov

index. Certain other material, such as copyrighted material, will be publicly available only in hard copy. Publicly available docket materials are available either electronically in

http://www.regulations.gov

or in hard copy at the EPA Docket Center, Standards of Performance for Portland Cement Plants Docket, EPA West, Room 3334, 1301 Constitution Ave., NW., Washington, DC. The Public Reading Room is open from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding legal holidays. The telephone number for the Public Reading Room is (202) 566-1744, and the telephone number for the Docket Center is (202) 566-1742.

FOR FURTHER INFORMATION CONTACT:

Mr. Keith Barnett; Office of Air Quality Planning and Standards; Sector Policies and Programs Division, Metals and Minerals Group (D243-02); Environmental Protection Agency; Research Triangle Park, NC 27711; telephone number: (919) 541-5605; fax number: (919) 541-5450; e-mail address:

barnett.keith@epa.gov.

SUPPLEMENTARY INFORMATION:

The supplementary information presented in this preamble is organized as follows:

I. General Information

A. Does this action apply to me?

B. Where can I get a copy of this document?

C. Judicial Review

II. Background Information on the NESHAP, 40 CFR Part 63, Subpart LLL

A. What is the statutory basis for the NESHAP in 40 CFR part 63, subpart LLL?

B. Summary of the National Lime Association v. EPA Litigation

C. EPA's Response to the Remand

D. Reconsideration of EPA Final Action in Response to the Remand

III. Background Information From the NSPS 40 CFR Part 60, Subpart F

IV. Summary of EPA's Final Action on Amendments

A. What are EPA's final actions on 40 CFR part 63, subpart LLL?

B. What are EPA's final actions on 40 CFR part 60, subpart F?

C. What is EPA's sector-based approach?

V. Responses to Major Comments

A. What are the significant comments and responses on 40 CFR part 63, subpart LLL?

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

VI. Summary of Cost, Environmental, Energy, and Economic Impacts of the Final Amendments to Subpart LLL and Subpart F

VII. Statutory and Executive Order Reviews

A. Executive Order 12866: Regulatory Planning and Review

B. Paperwork Reduction Act

C. Regulatory Flexibility Act

D. Unfunded Mandates Reform Act

E. Executive Order 13132: Federalism

F. Executive Order 13175: Consultation and Coordination With Indian Tribal Governments

G. Executive Order 13045: Protection of Children From Environmental Health Risks and Safety Risks

H. Executive Order 13211: Actions Concerning Regulations That Significantly Affect Energy Supply, Distribution, or Use

I. National Technology Transfer Advancement Act

J. Executive Order 12898: Federal Actions To Address Environmental Justice in Minority Populations and Low-Income Populations

K. Congressional Review Act

I. General Information

A. Does this action apply to me?

Categories and entities potentially regulated by this final rule include:

see also

63 FR at 14193 (March 24, 1998) (area source cement kilns' emissions of mercury, dibenzo-p-dioxins and dibenzo-p-furans, POM, and PCB are subject to MACT).

Section 129(a)(1)(A) of the CAA requires EPA to establish specific performance standards, including emission limitations, for “solid waste incineration units” generally, and, in particular, for “solid waste incineration units combusting commercial or industrial waste” (CAA section 129(a)(1)(D)).

CAA section 129 refers to the Solid Waste Disposal Act (SWDA). However, this Act, as amended is commonly referred to as RCRA.

Section 129 of the CAA defines “solid waste incineration unit” as “a distinct operating unit of any facility which combusts any solid waste material from commercial or industrial establishments or the general public.” CAA Section 129(g)(1). CAA Section 129 also provides that “solid waste” shall have the meaning established by EPA pursuant to its authority under the Resource Conservation and Recovery Act (RCRA). Section 129(g)(6).

Natural Resources Defense Council

EPA,

489 F. 3d 1250, 1257-61 (DC Cir. 2007), the Court vacated the Commercial and Industrial Solid Waste Incineration Units (CISWI) Definitions Rule, 70 FR 55568 (Sept. 22, 2005), which EPA issued pursuant to CAA section 129(a)(1)(D).

In response to the Court's remand and vacatur of the CISWI Definitions rule, EPA initiated a rulemaking to identify which secondary materials are non-hazardous “solid waste” for purposes of subtitle D (non-hazardous waste) of the RCRA when burned in a combustion unit.

See

75 FR 31844 (June 4, 2010). Any final definition adopted in that rulemaking, in turn, will determine the applicability of CAA section 129(a) (

i.e.,

any combustion unit that burns any non-hazardous secondary material that is considered to be a solid waste would be subject to CAA section 129 requirements).

There is presently no Federal regulatory interpretation of “solid waste” for EPA to apply under Subtitle D of RCRA for purposes of CAA section 112 and 129. EPA is not prejudging, and cannot prejudge the outcome of the recently proposed non-hazardous solid waste rulemaking. EPA therefore cannot reliably determine at this time if the non-hazardous secondary materials combusted by cement kilns are to be classified as solid wastes. Accordingly, EPA is basing all determinations as to source classification on the emissions information now available, as required by CAA section 112(d)(3), and will necessarily continue to do so until the solid waste definition discussed above is promulgated. The current data base classifies all Portland cement kilns as CAA section 112 sources (

i.e.,

subject to regulation under CAA section 112).

We proposed amendments to the Portland Cement Manufacturing NESHAP on May 6, 2009.

See

74 FR 21136. We received a total of 3,229 comments from the Portland cement industry, environmental groups, State environmental agencies and others during the comment period. This final rule reflects our consideration of all the comments we received. Detailed responses to the comments not included in this preamble are contained in the Summary of Public Comments and Responses document, which is included in the docket for this rulemaking.

B. Summary of the National Lime Association v. EPA Litigation

On June 14, 1999 (64 FR 31898), EPA issued the NESHAP for the Portland Cement Manufacturing Industry (40 CFR part 63, subpart LLL).

The 1999 final rule established emission limitations for PM as a surrogate for non-volatile HAP metals (major sources only), dioxins/furans, and for greenfield

new sources total THC as a surrogate for organic HAP. These standards were intended to be based on the performance of MACT pursuant to CAA sections 112(d)(2) and (3). We did not establish limits for THC for existing sources and non-greenfield new sources, nor for HCl or mercury for new or existing sources. We reasoned that emissions of these constituents were a function of raw material concentrations and so were essentially uncontrolled, the result being that there was no level of performance on which a floor could be based. EPA further found that beyond the floor standards for these HAP were not warranted.

Cement kilns which burn hazardous waste are a separate source category, since their emissions of many HAP differ from Portland cement kilns' as a result of the hazardous waste inputs. Rules for hazardous waste-burning cement kilns are found at subpart EEE of part 63.

For purposes of the 1999 rule a new greenfield kiln is a kiln constructed after March 24, 1998, at a site where there are no existing kilns.

Ruling on petitions for review of various environmental groups, the DC Circuit held that EPA had erred in failing to establish CAA section 112(d) standards for mercury, THC (except for greenfield new sources) and HCl. The court held that “[n]othing in the statute even suggests that EPA may set emission levels only for those * * * HAPs controlled with technology.”

National Lime Ass'n

EPA,

233 F. 3d 625, 633 (DC Cir. 2000). The court also stated that EPA is obligated to consider other pollution-reducing measures such as process changes and material substitution.

Id.

at 634 (“the absence of technology-based pollution control devices for HCl, mercury, and total hydrocarbons did not excuse EPA from setting emission standards for those pollutants”). Later cases go on to hold that EPA must account for levels of HAP in raw materials and other inputs in establishing MACT floors, and further hold that sources with low HAP emission levels due to low levels of HAP in their raw materials can be considered best performers for purposes of establishing MACT floors.

See, e.g., Cement Kiln Recycling Coalition

EPA,

255 F. 2d 855, 865-66 (DC Cir. 2001);

Sierra Club

EPA

(“Brick MACT”), 479 F. 3d 875, 882-83 (DC Cir. 2007).

In the remainder of the opinion, the Court in

National Lime Ass'n

upheld EPA's standards for PM and dioxin (on grounds that petitioner had not properly raised arguments in its opening brief), upheld EPA's use of PM as a surrogate for HAP metals, and remanded for further explanation EPA's choice of an analytic method for HCl.

C. EPA's Response to the Remand

In response to the

National Lime Ass'n

mandate, on December 2, 2005, we proposed standards for mercury, THC, and HCl. (More information on the regulatory and litigation history may be found at 70 FR 72332, December 2, 2005.) We received over 1,700 comments on the proposed amendments. Most of these comments addressed the lack of a mercury emission limitation in the proposed amendments. On December 20, 2006 (71 FR 76518), EPA published final amendments to the NESHAP. The 2006 amendments contained a new source standard for mercury emissions from cement kilns and kilns/in-line raw mills of 41 micrograms per dry standard cubic meter, or alternatively the application of a limestone wet scrubber with a liquid-to-gas ratio of 30 gallons per 1,000 actual cubic feet per minute of exhaust gas. The final rule also adopted a standard for new and existing sources banning the use of utility boiler fly ash in cement kilns where the fly ash mercury content has been increased through the use of activated carbon or any other sorbent unless the cement kiln seeking to use the fly ash can demonstrate that the use of fly ash will not result in an increase in mercury emissions over its baseline mercury emissions (

i.e.,

emissions not using the mercury-laden fly ash). EPA also issued a THC standard for new cement kilns (except for greenfield cement kilns that commenced construction on or before December 2, 2005) of 20 parts per million (corrected to 7 percent oxygen) or 98 percent reduction in THC emissions from uncontrolled levels. EPA did not set a standard for HCl, determining that HCl was a pollutant for which a threshold had been established, and that no cement kiln, even under conservative operating conditions and exposure assumptions, would emit HCl at levels that would exceed that threshold level, allowing for an ample margin of safety. EPA pointed to CAA section 112(d)(4) authority as its rationale for not establishing HCl emissions limits.

D. Reconsideration of EPA Final Action in Response to the Remand

At the same time we issued the final amendments, EPA on its own initiative made a determination to reconsider the new source standard for mercury, the existing and new source standard banning cement kiln use of certain mercury-containing fly ash, and the new source standard for THC (71 FR 76553, December 20, 2006). EPA granted reconsideration of the new source mercury standard both due to substantive issues relating to the performance of wet scrubbers and because information about their performance in the industry had not been available for public comment at the time of proposal; that information is now available in the docket. We also committed to undertake a test program for mercury emissions from cement kilns equipped with wet scrubbers that would enable us to resolve these issues. We further explained that we were granting reconsideration of the work practice requirement banning the use of certain mercury-containing fly ash in cement kilns to allow further opportunity for comment on both the standard and the underlying rationale and because we did not feel we had the level of analysis we would like to have to support a beyond-the-floor determination. We granted reconsideration of the new source standard for THC because the information on which the standard was based arose after the period for public comment. We requested comment on the actual standard, whether the standard is appropriate for reconstructed new sources (if any should occur) and the information on which the standard is based. We specifically solicited data on THC emission levels from preheater/precalciner cement kilns. We stated that we would evaluate all data and comments received, and determine whether in light of those data and comments it was appropriate to amend the promulgated standards.

EPA received comments on the notice of reconsideration from two cement companies, three energy companies, three industry associations, a technical consultant, one State, one environmental group, one ash management company, one fuels company, and one private citizen. As part of these comments, one industry trade association submitted a petition to withdraw the new source MACT standards for mercury and THC and one environmental group submitted a petition for reconsideration of the 2006 final action. A summary of these comments is available in the docket for this rulemaking.

Summary of Comments on December 20, 2006 Final Rule and Notice of Reconsideration. April 15, 2009.

In addition to the reconsideration discussed above, EPA received a petition from Sierra Club requesting reconsideration of the existing source standards for THC, mercury, and HCl, and judicial petitions for review challenging the final amendments. EPA granted the reconsideration petition. The judicial petitions have been combined and are being held in abeyance pending the results of the reconsideration.

In March 2007 the DC Circuit Court issued an opinion (

Sierra Club

EPA,

479 F.3d 875 (DC Cir. 2007) (

Brick MACT

)) vacating and remanding CAA section 112(d) MACT standards for the Brick and Structural Clay Ceramics source categories. Some key holdings in that case were:

• Floors for existing sources must reflect the average emission limitation achieved by the best performing 12 percent of existing sources, not levels EPA considers to be achievable by all sources (479 F. 3d at 880-81);

• EPA cannot set floors of “no control.” The Court reiterated its prior holdings, including

National Lime Ass'n,

confirming that EPA must set floor standards for all HAP emitted by the major source, including those HAP that are not controlled by at-the-stack control devices (479 F. 3d at 883); and

• EPA cannot ignore non-technology factors that reduce HAP emissions, including when determining which sources are best performers for purposes of ascertaining the MACT floor. Specifically, the Court held that “EPA's decision to base floors exclusively on technology even though non-technology factors affect emissions violates the Act.” (479 F. 3d at 883).

Based on the statute, as interpreted in the

Brick MACT

decision, we believe a source's performance resulting from the presence or absence of HAP in raw materials must be accounted for in establishing floors;

i.e.,

a low emitter due to low HAP proprietary raw materials can still be a best performer. In addition, the fact that a specific level of performance is not being intentionally achieved by the source is not a legal basis for excluding the source's performance from consideration.

Sierra Club

EPA,

479 F.3d at 631-34;

National Lime Ass'n,

233 F. 3d at 640.

The

Brick MACT

decision also reiterated that EPA may account for variability in setting floors. However, the Court found that EPA erred in assessing variability because it relied on data from the worst performers to estimate best performers' variability, and held that “EPA may not use emission levels of the worst performers to estimate variability of the best performers without a demonstrated relationship between the two.” 479 F. 3d at 882.

After considering the implications of this decision, EPA granted the petition for reconsideration of all the existing source standards in the 2006 rulemaking.

A second Court opinion of relevance to the Portland cement NESHAP amended here is

Sierra Club

EPA,

551 F. 3d 1019 (DC Cir. 2008). In that case, the court vacated the regulations contained in the General Provisions which exempt major sources from CAA section 112(d) standards during periods of startup, shutdown and malfunction (SSM). The regulations (in 40 CFR 63.6(f)(1) and 63.6(h)(1)) provided that sources need not comply with the relevant CAA section 112(d) standard during SSM events and instead must “minimize emissions * * * to the greatest extent which is consistent with safety and good air pollution control practices.” The current Portland Cement NESHAP references the now-vacated rules in the General Provisions. As a result of the court's decision, we are removing the references to the vacated provisions and addressing SSM in this rulemaking. Discussion of this issue may be found in Section IV.A.

III. Background Information on the NSPS 40 CFR Part 60, Subpart F

NSPS implement CAA section 111(b) and are issued for categories of sources which cause, or contribute significantly to, air pollution which may reasonably be anticipated to endanger public health or welfare. The primary purpose of the NSPS is to attain and maintain ambient air quality by ensuring that the best demonstrated emission control technologies are installed as the industrial infrastructure is modernized. Since 1970, the NSPS have been successful in achieving long-term emissions reductions in numerous industries by assuring cost-effective controls are installed on new, reconstructed, or modified sources.

Section 111 of the CAA requires that NSPS reflect the application of the best system of emission reductions which, taking into consideration the cost of achieving such emission reductions, any non-air quality health and environmental impact and energy requirements, the Administrator determines has been adequately

demonstrated. This level of control is commonly referred to as best demonstrated technology (BDT). EPA promulgated Standards of Performance for Portland Cement Plants (40 CFR, part 61 subpart F) in 1971 ((36 FR 24876, December 23, 1971).

Section 111(b)(1)(B) of the CAA requires EPA to periodically review and revise the standards of performance, as necessary, to reflect improvements in methods for reducing emissions. We have conducted three reviews of the standards (39 FR 20793, June 14, 1974; 39 FR 39874, November 12, 1974; and 53 FR 50354, December 14, 1988).

We proposed the current review of the Portland Cement Plant NSPS on June 16, 2008. We received a total of 46 comments from the Portland cement industry, environmental groups, State environmental agencies and others during the comment period. This final rule reflects our consideration of all the comments we received. Detailed responses to the comments not included in this preamble are contained in the Summary of Public Comments and Responses document which is included in the docket for this rulemaking.

IV. Summary of EPA's Final Action on the Amendments

In this section we discuss the final amendments to 40 CFR part 63 subpart LLL and part 60 subpart F, the changes since proposal, and the rationale for the changes. Responses to specific comments may be found in the response to comment section of this document or in the response to comment documents contained in the dockets for this rulemaking.

As a preliminary matter, EPA notes that certain portions of the existing rules are not being amended substantively but are being reprinted, sometimes with editorial changes, in today's regulatory text. As explained at proposal, EPA did so either for readers' convenience or to make certain non-substantive “plain English” changes to rule text. 74 FR at 21140. The final rule text makes these same non-substantive changes (which did not occasion public comment), and reprints certain existing provisions. Provisions from the existing rules which do not change substantively include the PM emission limits for kilns currently subject to the NSPS, the opacity limits for raw materials dryers, raw mills, and finish mills, and the limits for dioxin furan (D/F) for cement kilns. We reorganized the testing and monitoring requirements of both rules to make them more consistent, and modified the rule language to better conform with the June 1, 1998, Executive Memorandum on Plain Language in Government Writing.

A. What are EPA's final actions on 40 CFR part 63, subpart LLL?

1. What are the final actions on emission limits under 40 CFR part 63, subpart LLL?

In this action, we are amending the emission limits for mercury, THC, and PM from new and existing kilns located at a major or area source, and for HCl from new and existing kilns located at major sources. We identify these standards below for the emission sources in a typical Portland cement production process. We have applied the limits for existing and new sources in this final rule for mercury and THC to area sources consistent with CAA section 112(c)(6). As noted above, mercury is one of the pollutants specifically singled out by Congress in CAA section 112(c)(6), and THC is a surrogate for POM and PCB, which are also section 112(c)(6) HAP.

See

63 FR 14193, March 24, 1998 (determination to control all THC emissions from the source category under MACT standards). Finally, Portland cement kilns are a listed area source category for urban HAP metals pursuant to CAA section 112(c)(3), and control of these metal HAP emissions (via the standard for the PM non-mercury HAP metal surrogate) is required to ensure that area sources representing 90 percent of the area source emissions of urban metal HAP are subject to CAA section 112 control, as required by CAA section 112(c)(3). The PM standards for area sources reflect MACT, as explained below.

a. Changes to Overall Floor Setting Procedure

The MACT floor limits for each of the HAP and HAP surrogates (mercury, THC, HCl, and PM) are calculated based on the performance of the lowest emitting (considered best performing in this rulemaking) sources in each of the MACT floor pools for each HAP or HAP surrogate. We ranked all of the sources for which we had data based on their emissions and identified the lowest emitting 12 percent of the sources for which we had data, which ranged from two kilns for THC to 11 kilns for mercury for existing sources. For new source MACT, the floor was based on the best controlled source.

In assessing sources' performance, EPA may consider variability both in identifying which performers are “best” and in assessing their level of performance.

Brick MACT,

479 F. 3d at 881-82;

see also

75 FR at 32019-20.

EPA was able to reasonably calculate variability for the THC and HCl standards without needing to use predictive statistics. Specifically, the data set for THC contains a sufficient number of observations to estimate the variability without the need of any type of statistical intervals (no UPL needed to be calculated). For HCl, although EPA applied the UPL formula in developing the HCl standard, the key issue for the HCl data set is the HCl analytic method's detection limit, which ultimately dictated the level of the standard.

At proposal we adopted a form of the UPL equation that has been used in a previous rulemaking. 69 FR 21233 April 20, 2004. Commenters stated correctly that there was an error in the equation used at proposal. As a result of these comments, EPA corrected the formula in the final rule. The UPL used in the final rule is calculated by:

ER09SE10.000

Where:

= the mean of the sample data set

n = the number of test runs

m = the number of test runs in the compliance average

= observed variance

t = student t distribution statistic

This calculation was performed using the following Excel functions:

Normal distribution:

99 percent UPL = AVERAGE(Test Runs in Top 12percent) + [STDEV(Test Runs in Top 12percent) x TINV(2 x probability, n-1 degrees of freedom)*SQRT((1/n)+(1/m))], for a one-tailed t-value, probability of 0.01, and sample size of n

This is the same UPL equation that EPA used in more recent rulemakings.

See

75 FR 32020 (June 4, 2010) and 75 FR 31905 (June 4, 2010). The value of “m” denotes the number of future observations, and it is used to calculate an estimate of the variance of the average of m-future observations. For example, if 30-day averages are used to determine compliance (m=30), the amount of variability in the 30-day average is much lower than the variability of the daily measurements in the data base, which results in a lower UPL for the 30-day average.

As an illustration of the effects that correcting the UPL had on the emission limits, we calculated the UPLs for mercury and PM using the proposal version of the UPL formula, and the version used in this final rule. The results of these calculations are presented in Table 1. Both calculated limits are about 20 percent lower when the corrected UPL formula is used.

Table 1—Comparison Emission Limits Calculated Using Proposal UPL Formula Versus Corrected UPL Formula for Existing Sources

Proposal

(uncorrected

UPL formula)

Proposal

(corrected

UPL formula)

Mercury, (lb/MM tons feed) [lb/MM tons clinker]

29.6 [48.8]

22.5 [37.1]

PM (lb/ton clinker)

0.05

0.04

b. Ramifications of EPA Statistical Approach

A number of commenters maintained that this final rule raises the (perceived) quandry voiced by Judge Williams in his concurring opinion in

Brick MACT

where an achieved level of performance for purposes of CAA section 112(d)(3) results in a standard which is unachievable under CAA section 112(d)(2) because it is too costly or not cost-effective.

Brick MACT,

479 F. 3d at 884-85. EPA is of course mindful of the repeated admonitions (with accompanying vacaturs and remands) from the DC Circuit that MACT floors must reflect achieved performance, that HAP content of process inputs (raw materials and fuels) must be accounted for in ascertaining sources' performance, and that costs cannot be considered by EPA in ascertaining the level of the MACT floor.

See, e.g., Brick MACT,

479 F. 3d at 880-81, 882-83;

NRDC

EPA,

489 F. 3d 1364, 1376 (DC Cir. 2007) (“Plywood MACT”);

see also Cement Kiln Recycling Coalition

EPA,

255 F. 3d 855, 861-62 (DC Cir. 2001) (“achievability” requirement of CAA section 112(d)(2) cannot override the requirement that floors be calculated on the basis of what best performers actually achieved). EPA is also mindful of the need to account for sources' variability (both due to control device

performance and variability in inputs) in assessing sources' performance when developing technology-based standards.

See, e.g.,

Mossville Environmental Action Now

EPA,

370 F. 3d 1232, 1242 (DC Cir. 2004);

National Lime I,

627 F. 2d 416,433-34(DC Cir. 1980). EPA has carefully developed data for each standard, assessing both technological controls and HAP inputs in doing so. For mercury, EPA used the pooled variance from all of the best performing kilns in the MACT floor pool in order to fully assess these kilns' intra-quarry and other variable mercury levels. EPA also used pooled variance to assess the variability of HCl and PM emissions for the MACT floor pool kilns.

See

70 FR at 59438 (Oct. 12, 2005) (explaining when use of such pooled variances can be reasonable). 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 floors which reasonably estimate the performance over time of the best performing sources, as do the standards based on those floors. It is true that many sources will need to install controls to meet these standards, and that these controls have significant costs (although EPA estimates that the rule's costs are substantially outweighed by its benefits).

See

Section VI below. This is part of the expected MACT process where, by definition, the averaged performance of the very best performers sets the minimum level of the standard. The Agency believes that it has followed the statute and applicable case law in developing its floor methodology.

Industry commenters nonetheless maintained that EPA had not properly accounted for variability of the best performing sources because not even these sources can meet the standards which are predicated on their own performance without adding controls. This contention lacks a basis in the record. For mercury, all performers in the MACT floor pool—not just those with emissions below the average of the best performers— meet the promulgated standard (highest 30-day average in MACT pool is 41.63 lb/MM tons clinker; the standard is 55 lb/MM tons clinker (30-day average). In addition, several additional kilns, which are not in the pool of best performers, meet the standards. For THC, all kilns in the pool of best performers meet the promulgated standard (highest 30-day average in MACT pool is 5.68 ppmv; the standard is 24 ppmv). In addition, seven additional kilns which are not in the pool of best performers meet the standards. Indeed, nine of the 11 kilns for which EPA has CEM data are meeting the promulgated standards for THC. For PM, all six kilns in the MACT pool as well as twelve kilns overall meet the promulgated 30-day standard even though the measurements in the data base are stack tests (

i.e.,

unlike for mercury and THC, these are not averaged values).

Virtually all kilns in the MACT floor pool are meeting the HCl standard, although this is largely the result of setting the standard at a level reflecting analytic method quantitation limits.

Development of The MACT Floors For The Final NESHAP For Portland Cement. August 6, 2010.

Commenters presented virtually no quantified data that floor plants are unable to meet the standards.

See National Association of Metal Finishers

EPA,

719 F. 2d 624, 649 (3d Cir. 1983) (unquantified assertions are entitled to little if any weight). Rather, their comments (comment 2845 at Table 1, echoed by many other industry commenters) provided narrative descriptions purporting to demonstrate that floor plants would not be able to achieve the standards.

In those instances where commenters provided actual data on these plants' performance, EPA took the information into account in developing the final standards. Indeed, EPA adjusted all of the standards based on actual data presented. However, EPA is not willing to act on pure supposition and conjecture regarding variability, particularly in the face of record information indicating that not only all floor plants but a number of additional plants are already meeting the promulgated standards.

For example, the commenter asserted, without providing support, that for the floor kilns the standards were “achieved in practice, but not under foreseeable operations”; “achieved in practice based on limited stack tests”; “data shows that proposed standard was not achieved in practice when malfunction emission [sic] are included in compliance determination” (although no such data were provided to EPA).

c. Mercury Limits for Kilns

i. Floor Determination.

We proposed mercury emissions limits of 43 lb/million (MM) tons clinker for existing sources and 14 lb/MM tons clinker for new sources. The proposed floor was based on 30 days of data on all kiln inputs for 89 kilns.

See

74 FR at 21142-43. For all kilns but the five equipped with wet scrubbers, emissions were assumed to equal the total mass of mercury fed to each kiln. Scrubber-equipped kilns were considered to emit all mercury minus an assumed amount representing the average performance of the wet scrubbers. For kilns that waste cement kiln dust (CKD), the mercury component of the CKD was subtracted from inputs to calculate emissions.

Id.

By conducting a total mass balance for mercury and then assuming that all mercury inputted is emitted (minus conservatively estimated removals for scrubber usage and dust wastage), EPA made a near worst case assumption as to kilns' mercury emission levels. The kilns were then ranked from best to worst based on the extrapolated mercury emissions, normalized to clinker production. EPA further proposed that no beyond the floor standard was appropriate for either existing or new sources.

Id.

at 21149.

Since proposal we received updated data on certain kilns' raw materials usage and mercury content

and used that data to revise our average mercury emissions estimates from the best performing kilns at proposal.

We have also revised upward the floor kilns' projected emissions based on their reasonably estimated intra-quarry variability (explained further below). As a result, estimated emissions from these kilns increased, and one of the kilns in the group of sources used to set the existing source floor is no longer one of the best performing kilns. At proposal, the average mercury emissions of the top 12 percent of the kilns was 27.4 pounds per million (lb/MM) tons clinker, and the average emissions of the best performing source were 13.4 lb/MM ton clinker. After revising our mercury emissions estimates, the averages were 32 and 14 lb/MM tons clinker, respectively, as shown in Table 2.

See

Portland Cement Association Comments on the NESHAP-Proposed Rule (Docket Number: EPA-HQ-OAR-2002-0051) (September 4, 2009) at pp. 31-35.

Development of The MACT Floors For The Final NESHAP For Portland Cement, August 6, 2010.

Table 2—Mercury MACT Floor

Kiln code

Mercury emissions

(lb/MM ton feed)

1589

8.48

1650

9.53

1315

15.26

1302

15.28

1248

16.63

1259

21.33

1286

22.65

1594

25.23

1435

25.51

1484

25.51

1364

25.91

MACT—Existing Kilns

Average: lb/MM tons feed (lb/MM tons clinker)

19.21 (31.7)

Total variance

272.3

UPL: lb/MM tons feed (lb/MM tons clinker)

32.8 (54.1)

MACT—New Kilns

Average: lb/MM tons feed (lb/MM tons clinker)

8.48 (14.0)

Total variance

35.2

UPL: lb/MM tons feed (lb/MM tons clinker)

12.3 (20.3)

As noted above, we are taking into account operating variability of the best performing kilns, or in the case of new source MACT the single best controlled kiln, in assessing their performance (

i.e.,

both in determining which performers are best, and calculating what their performance is). When we calculated the UPL with 99 percent confidence for the best performing sources (or in the case of new source MACT the best controlled single source), we calculated a mercury floor of 55 lb/MM tons clinker for existing sources and 21 lb/MM tons clinker for new sources. We chose a 30-day averaging period for the mercury emission limit. As noted above, the use of a 30-day average (as opposed to hourly or daily averages) tends to reduce variability, and also best reflects the nature of the data from which the floor was derived and assures that several operating cycles of raw mill on and off are included in each average.

Id.

at 21144.

Industry commenters stated that we should account for additional sources of variability in this floor determination, namely intra-quarry variability and variability of the mercury content in local coals which kilns could utilize. As explained below, beyond those situations where commenters documented that sources actually used inputs with greater mercury content than used during the 30-day test period (

see

note 11 above), or where further intra-quarry mercury variability could reasonably be estimated, we did not do so.

EPA is of course aware that limestone quarries are immense, and are customarily used from periods of 50 to 100 years. Taking the average of 30 days of sampling data from one part of the quarry would not necessarily encompass all of the different mercury levels throughout the quarry.

Although industry commenters originally raised the issue of long term intra-quarry variability during the initial May 2007 30-day data collection, no plant chose to perform additional sampling and analysis of their raw materials and feed that would have allowed this issue to be directly addressed. Certain industry commenters did point, however, to data from the 30-day sampling effort as providing useful information on potential intra-quarry mercury variability of the two best performers. The data come from 30-day sampling conducted at four sources (three of which are located at a single facility), which all quarry limestone from a common geologic limestone formation.

All six kilns (the two floor kilns, and the other four kilns in the immediate vicinity) are in the same city and within 9 miles of each other. It is a reasonable assumption that variability of mercury levels (as opposed to mercury levels themselves) across this formation are substantially the same and therefore that the variability of mercury levels in the two best performers' quarries can be adjusted to reflect the variability seen in the other quarries which are part of the common geologic formation.

See Brick MACT,

479 F. 3d at 881-882 (EPA may look at performance of sources which are not among the best in estimating variability of best performers if there is a demonstrated relationship between the two).

Memorandum. Intra-quarry Variability Estimate, July 21, 2010.

EPA further applied these estimates of intra-quarry variability to the mercury data for the other best performing kilns (

i.e.,

applied the same RSD to the other best performing sources). EPA did so to more robustly characterize long-term variability of these sources' quarries' mercury levels. The fact that intra-quarry variability of the two lowest emitting sources increased somewhat after examination with other quarries in the common geologic formation confirms that there can be further variability. Since the intra-quarry variability comes from quarries servicing the two lowest emitting kilns, EPA would not expect intra-quarry variability to be lower for the other best performing sources. In no other instance did commenters provide data that we could use to determine intra-quarry variability for kilns in the MACT floor pool.

For example, one industry commenter submitted core (unground, unprocessed) samples from its quarry which samples differed in mercury content by approximately one order of magnitude. This facility is not a best performer, the samples are single measurements (rather than 30-day measurements or some longer duration), and (unlike the 30-day measurements used as the basis for the standard) have not been processed (

i.e.,

passed through the quarry crushers and mixed in the storage pile which would tend to make the material more homogeneous). Therefore, these data are not comparable to the data used to set the MACT floors.

Commenters also maintained that because cement kilns can burn different types of coal, variability of coal mercury content needs to be factored into estimates of sources' performance. Commenters maintained that they obtained coal from a “local market” and so might eventually use any coal from that market. The comments did not further link coal to individual mines or to other particularized sources. Commenters appear to be asking for an upward adjustment of the MACT floors based on coal they might potentially use but never had used. EPA believes that allowing for any inputs that might conceivably be used in the future, including from sources in an area which a source has never used to date, goes beyond a reasonable estimate of performance over time and invites inflated estimates of variability based only on hypothesized possibilities, not on actual behavior.

EPA not only does not believe such methodology is a reasonable means of calculating sources' achieved performance, but also believes that such an approach creates a perverse incentive to build in compliance margins based on seeking out more polluted inputs.

The situation differs from use of limestone from a proprietary quarry. Not only have sources used the quarry in the past but will necessarily continue to do so in the future.

For example, the price of lower mercury coal may increase as a result of this rule (it may be more desirable as a means of keeping mercury emissions low), so plants may seek out higher mercury coal which they otherwise have never used. This type of volitional activity does not seem to be within the ambit of normal variability of process inputs. In addition, facilities do have choices for coal. As noted in the comments, some facilities obtain coals from several States, while others appear to limit themselves to more local areas. However, coal is a commodity that can be transported long distances to fuel utility boilers. Therefore, we believe that a facility should have sufficient coals available that they would not be compelled to use a higher mercury coal just because it happens to be near the plant.

ii. Decision Regarding Whether To Create a Subcategory Based on Limestone Mercury Content

EPA may create subcategories which distinguish among “classes, types, and sizes of sources.” CAA section 112(d)(1). EPA reads this provision to provide the Agency with discretion to subcategorize,

and EPA may exercise that discretion if sources are rationally distinguishable due to some difference in class, type or size.

See Lignite Energy Council

EPA,

198 F. 3d 930, 933 (DC Cir. 1999) (“EPA is not required by law to subcategorize—section 111[b][2] merely states that `the Administrator

may

distinguish among classes, types, and sizes within categories of new sources' ” (emphasis original)). Moreover, as we noted at proposal, “normally, any basis for subcategorizing must be related to an effect on emissions, rather than to some difference among sources which does not affect emissions performance.” 74 FR at 21145. EPA may also exercise this discretion on a pollutant-specific basis, since the difference in class, type or size may only have practical significance for certain HAP. In this final rule, EPA carefully considered the possibility of creating different subcategories of cement kilns with respect to mercury emissions.

The subcategorization possibilities for mercury which we considered and rejected at rule proposal were the type of kiln, presence of an inline raw mill, practice of wasting cement kiln dust, total mercury inputs, or geographic location.

See

74 FR 21144-21145. We likewise reject these bases in this final rules for the reasons already stated.

At proposal we also considered subcategorizing by the mercury concentration of the limestone in the kiln's proprietary quarry. We did not propose to create this type of subcategory, and also choose not to do so in this final rule.

As we explained at proposal, the facts do not indicate sharp disparities in limestone mercury content that readily differentiate among types of sources for most of the facilities for which we have data, and thus do not support this subcategorization approach for the majority of the facilities.

See

Figure 1 showing a gradual continuum of mercury concentrations in limestone for all but two outlying plants.

ER09SE10.001

Industry commenters who supported creating a separate subcategory for the two highest mercury emitting sources based on limestone mercury content agreed with this assessment. Thus, EPA sees no technical justification to subcategorize by limestone quarry mercury content for the majority of the source category.

However, as also shown in Figure 1, there is a sharp disparity for two kilns which have the highest quarry mercury contents. These sources' mercury emissions are also disproportionately higher than all other cement kilns', and are related almost entirely to the limestone mercury content, not to mercury content of other inputs. Commenters who supported subcategorization by quarry mercury levels recommended that EPA create a separate source category for these two kilns based on their uniquely high quarry mercury contents.

If we were to set a separate subcategory for these two kilns, we determined that the floor level of control would be approximately 2100 lb/MM tons clinker. Due to the high level of this floor, we evaluated a beyond-the-floor option of 85 percent reduction in emission for the highest emitting kiln. This level would represent the highest level of mercury control believed achievable for the highest emitting facility based on test data on a pilot mercury control system for that facility.

This level of control would result in an emissions limit of

approximately 500 lb/MM tons clinker. This level is over 10 times the level that will be required for all other kilns, and even exceeds every other kiln's uncontrolled mercury emissions levels which range from 20 to 400 lb/MM tons clinker.

Letter, C. Lesslie, Ash Grove Cement to P. Tsirigotis, U.S. EPA, April 22, 2010.

Mercury in the air eventually settles into water or onto land where it can be washed into water. Once deposited, certain microorganisms can change it into methylmercury, a highly toxic form that builds up in fish, shellfish and animals that eat fish. Fish and shellfish are the main sources of methylmercury exposure to humans. Methylmercury builds up more in some types of fish and shellfish than in others. The levels of methylmercury in fish and shellfish depend on what they eat, how long they live and how high they are in the food chain. Mercury exposure at high levels can harm the brain, heart, kidneys, lungs, and immune system of people of all ages. Research shows that most people's fish consumption does not cause a health concern. However, it has been demonstrated that high levels of methylmercury in the bloodstream of unborn babies and young children may harm the developing nervous system, making the child less able to think and learn.

Heightened concern for mercury's toxic effects is reflected directly in the structure of section 112 of the Act. Mercury is one of the pollutants identified for MACT-level control under the CAA's air toxics provision even (in most instances) when emitted by area sources (

see

CAA section 112(c)(6)).

For more information

see http://www.epa.gov/mercury/about.htm.

Thus, creating a high-mercury subcategory for two kilns based on limestone mercury content would result in standards allowing emissions of 500 lb/MM tons of clinker. Based on 2008 production rates, this would allow 1,020 pounds of mercury emissions per year from the potential two-plant subcategory. To put this in perspective, the rest of the industry (92 plants) would be allowed to emit 1,012 pounds tons of mercury per year (again based on 2008 production rates), and the two high-emitting plants would be allowed to emit 1,020 pounds per year. This would result in a doubling of mercury emissions from this source category after the application of MACT. Moreover, national mercury emissions for industrial sources are approximately 50 tpy.

That would mean that these two sources alone would constitute 1 percent of the industrial mercury emissions for the U.S. EPA believes it is a reasonable exercise of discretion not to create a subcategory, where, as here, doing so would allow on-going emissions of a disproportionately high volume of a high-toxicity pollutant.

Mercury Emission in the U.S. by Source Category 1990 to 1993, 2002, and 2005.

http://cfpub.epa.gov/eroe/index.cfm?fuseaction=detail.viewMidImg&ch=46&lShowInd=0&subtop=341&lv=list.listByChapter&r=188199.

Due to mercury's high toxicity and the extremely high mercury emissions that would result, the Administrator is thus not exercising her discretion to subcategorize in setting the final mercury emissions limit. In light of this decision, it is unnecessary for EPA to address the further question of whether subcategorizing by raw material content of proprietary quarries is permissible under section 112 of the Act.

Although the Agency has concluded that it is reasonable to set the same mercury standard for all cement kilns, we acknowledge the unique challenges that the highest emitting sources may face in meeting the reductions within the regulatory compliance timeline. In particular, as discussed at length above, the two highest emitting kilns—the kilns located in Durkee and Tehachapi—have unusually high levels of mercury in their proprietary limestone quarries, which, as typifies this sector, are located proximate to kiln operations. The mercury content of source material is the key factor in the high levels of emissions experienced at these kilns and a complicating consideration in their ability to achieve compliance in a timely manner.

We also recognize that this challenge presents a unique opportunity to achieve substantial reductions in this naturally occurring, persistent, and widespread contaminant in an amount and on a schedule that exceeds what will be required in the final rule. The Agency believes that the two sources in question may be able in the near term to install aggressive controls, including activated carbon injection, that would result in dramatic near term reductions in mercury emissions (as much as 90 percent or two tons of mercury emissions in the first two years of operation). If they were to do so, these sources would emit substantially less mercury in the next few years than the alternative of allowing these facilities to continue to emit at current levels for three additional years, as would otherwise be the case. This would be a very substantial reduction in emissions of this pollutant. Annual emissions of mercury from all sources (not just cement kilns) are estimated to be 50 tpy,

and emissions from the entire source category are approximately 7.5 tons per year,

so that a two ton reduction is a substantial reduction of mercury emissions.

Mercury Emission in the U.S. by Source Category 1990 to 1993, 2002, and 2005.

http://cfpub.epa.gov/eroe/index.cfm?fuseaction=detail.viewMidImg&ch=46&lShowInd=0&subtop=341&lv=list.listByChapter&r=188199.

Summary of Environmental And Cost Impacts For Final Portland Cement NESHAP And NSPS August 6, 2010.

We understand that one of the two high emitting kilns has already installed activated carbon injection, but that its performance could be further optimized.

See

74 FR 21148. The other kiln would have to install activated carbon injection and both kilns would need to install dust shuttling. The net benefit to the environment and public health would extend a number of years beyond the MACT compliance deadline.

If the Durkee and Tehachapi kilns were willing to make a near term reduction (

e.g.,

90 percent) in their mercury emissions significantly before the compliance date in the rule, the Agency would consider providing these kilns a compliance schedule that extends beyond the three to four years specified in this rule. The purpose of such an approach would be to provide a substantial net benefit to the environment; therefore ultimate compliance with the MACT standard would need to be by a date that ensures the long term emissions from these sources would be significantly lower than their emissions from meeting the standard on the schedule in the rule. Given the nature of mercury and the additional reductions that could be obtained, the Agency is interested in exploring this concept.

Finally, EPA notes that the same early reduction opportunities for mercury do not appear to exist for the rest of the Portland cement industry. It typically takes on the order of three years to install activated carbon injection technology. One of the high mercury plants has recently completed installation of ACI and has just commenced full scale operation of the kiln with ACI installed. The other kiln faces fewer installation barriers than other kilns. This is because the company has tested carbon injection and dust shuttling on one of its other kilns, and is already using dust shuttling to reduce emissions at another kiln, and is therefore better positioned to rapidly install controls after one year. To our knowledge, these circumstances are not applicable to the rest of the Portland cement source category, and could not even be duplicated at all the other facilities owned by these companies due to limitations in

infrastructure available to design and build these systems.

iii. Beyond the Floor Determinations for Mercury

We are basing the final mercury standard on the floor level of control. When we establish a beyond the floor standard we typically identify control techniques that have the ability to achieve an emissions limit more stringent than the MACT floor. Under these final amendments, most existing kilns would have to have installed both a wet scrubber and activated carbon injection (ACI) for control of mercury, HCl and THC.

To achieve further reductions in mercury beyond what can be achieved using wet scrubber and ACI in combination, the available options would include closing the kiln and relocating to a limestone quarry having lower mercury concentrations in the limestone, transporting low-mercury limestone in from long distances, switching other raw materials to lower the amount of limestone in the feed, wasting CKD, and installing additional add-on control devices. These options were discussed at proposal, and were rejected as either technically infeasible or not cost-effective. Consideration of non-air quality impacts and energy requirements do not change this conclusion.

See

74 FR at 22249-50. We received no comments that would cause us to change that determination.

Summary of Environmental and Cost Impacts of Proposed Revisions to Portland Cement NESHAP (40 CFR Part 63, subpart LLL), April 15, 2009.

We did receive one comment from an environmental group requesting EPA explore fuel switching as a beyond the floor option. However, EPA thoroughly explored fuel switching as a control option in the 2006 rulemaking and determined that there were problems with fuel availability and the costs were prohibitive.

See

70 FR 72340. EPA is not presently aware of facts that would justify a different approach in this final rule.

As a result of these analyses, we determined that, considering the technical feasibility and costs, there is no reasonable beyond the floor control option, and the final mercury emission limit is based on the MACT floor level of control.

c. THC Limits for Kilns and Raw Material Dryers

The limits for existing and new sources in this final rule apply to both area and major sources. As noted earlier, we have applied these limits to area sources consistent with CAA section 112(c)(6).

i. Floor Determination.

EPA proposed THC emissions limits of 7 and 6 parts per million by volume dry (ppmvd) for existing and new sources respectively for both cement kilns and raw material dryers. The existing source standard was based on the performance of the best performing 12 percent of cement kilns for which we had THC CEMS data. At proposal we requested comment on the issue of whether or not we should base the existing source floor on the best performing five kilns, rather than on the best performing 12 percent (two kilns). Industry commenters supported the use of the best five kilns stating that this would be in keeping with what appeared to be the intent of Congress that five kilns should be the minimum number of sources on which to set an existing source floor. However, other commenters noted that a plain reading of the statute is that when the source category has 30 or more sources, the top performing 12 percent for which the Administrator has data must be used, even if this results in less than five facilities due to lack of available data. In this final rule we are reaffirming our decision at proposal to use the best performing 12 percent rather that the best performing five facilities because we believe this result to be unavoidably compelled by the literal language of the statute.

At proposal we set the emissions limit based on the 99th percentile of the available data. As a result of new data received after the comment period, we recalculated the averages of the kilns for which we had CEMS data and selected the best performing two kilns (12 percent of 15 total kilns) based on their average emissions.

See

Calculations of Floors for Final Portland Cement NESHAP dated August 6, 2010. Because these were large data sets (688 and 274 readings), we directly calculated the 99th percentile of the 30-day averages to determine the MACT floor which is 24 ppmvd.

This is shown in Table 3.

In other words, as noted above, EPA possesses sufficient THC data that it is not necessary to estimate variability by use of the UPL equation. Rather, variability is calculated directly from the THC data set comprised of the two lowest emitting sources.

ER09SE10.002

For new sources, we analyzed the data from the kiln with the lower numeric average to determine the 99th percentile of its performance. The result of this analysis was also a 24 ppmvd standard because this kiln had more variability (although a lower average performance) than the other kiln in the data set. This emission limit is based on a concentration measured dry, corrected to 7 percent oxygen and a 30-day average measured using a CEM.

ii. Additional THC data received too late to be considered in this rulemaking.

In addition to the THC CEMS data just discussed, we received another set of THC CEMS data from the Portland Cement Association (PCA). These data were not submitted to EPA until mid-June 2010, virtually too late for any consideration, much less considered analysis. This set consisted of THC CEMS data collected over periods ranging from 31 to 90 days for additional kilns not in the data base discussed above, as well as additional data from some of the kilns already in our data base. These additional data increased the total number of kilns with THC CEMS data to 30 kilns. The PCA also provided a floor analysis on this data set and recommended THC emissions limits. The data set as presented by PCA is shown in Table 4.

Table 4—Portland Cement Association: Determination of Size of Best Performing Pool for Proposed Sub-Categories for THC

[Mid-June 2010 data submission]

Sub category

Estimated U.S. population

Kilns for which data are available

Procedure for selecting pool of best performing kilns

Existing units

Rule

Pool size

New units

Major Non-Commingled Kilns

> 30

Best 12%

Best 1.

Major Commingled Kilns

< 30

Best 5

Best 1.

Area Kilns

< 30

Work Practices Standard.

In this analysis, the PCA proposed two subcategories: Kilns where the coal preparation mill exhaust is comingled with the kiln exhaust, and kilns where the coal preparation mill has a separate stack. The PCA maintains that subcategories are needed because emissions for the coal preparation mill (which are believed to be chiefly methane from the coal) will, all other things being equal, elevate the THC emissions of the kiln exhaust.

see also

63 FR at 14204. This drying process can potentially lead to organic HAP and THC emissions in a manner analogous to the release of organic HAP and THC emissions from kilns when hot kiln gas contacts incoming feed materials. The methods available for reducing THC emissions (and organic HAP) is the same technology described for reducing THC emissions from kilns and in-line kiln/raw mills. Based on the similarity of the emissions source and controls, we proposed to set the THC emissions limit of materials dryers at the same levels as the kilns.

Commenters noted that stand alone raw materials dryers have higher gas flows relative to the amounts of fuels burned. This results in higher oxygen concentrations, typically as high as 19 percent. They also noted that raw material dryers may have higher THC and lower HAP emissions because raw materials dryers operate at lower temperature than kilns (since the dryer only needs to operate at the temperature needed to remove free water), and that the residence times for dryers is considerably longer than for kilns.

However, although we agree that the exhaust oxygen contents of raw material dryers may be higher than occurs with a cement kiln, there are reasons to believe that dryers actually emit less hydrocarbons than kilns. Operating at lower temperatures, we would expect any hydrocarbons that are emitted from dryers to be only those with the highest volatility, and therefore that the potential for emissions of organic HAP would be less for dryers than for kilns. However, the longer residence times could tend to increase emissions. Therefore, making any conclusions on the emission of dryers relative to kilns is difficult. We also note that we are allowing dryers to also use the alternative organic HAP emissions limit, so if the surmise that organic HAP emissions are low relative to the cement kilns is correct, this alternative should be very viable for these sources.

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

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

d. Hydrochloric Acid Emissions From Kilns

In the proposed rule we based the proposed HCl emission limit for major sources on HCl data measured at 27 kilns using Method 321. The data in ppmvd corrected to 7 percent oxygen (O

) were ranked by emissions level and the top 12 percent (4 kilns) lowest emitting kilns identified as best

performing existing sources. The calculated MACT floors were 2 ppmvd and 0.1 ppmvd respectively.

i. Floor Determination.

Subsequent to proposal, we received comments that indicated we had inappropriately (albeit inadvertently) included certain natural area sources in the MACT floor analysis. We have removed those natural area sources from the floor analysis. In addition, many of the source tests were not actually EPA Method 321 tests; others lacked important quality assurance information. As a result, we issued letters under CAA section 114 authority requiring facilities that were major sources and that had previously submitted data to retest their facilities. We used this new data set to calculate a MACT floor. The data from the best performing three sources, as determined by average emissions during the test, are shown below in Table 7.

Table 7—HCl MACT Floor

Kiln

HCl emissions

(ppmvd at 7% O

)

0.34

0.44

0.46

MACT—Existing

Average (Top 3)

0.41

Variance

0.02

UPL

0.52

MACT—New

Average

0.34

Variance

0.0

UPL

0.34

However, these measurements are very close to the detection limit for analytic method 321 actually calculated in the field for HCl—from 0.2 to 0.3 parts per million by volume (ppmv) as measured in the stack.

The expected measurement imprecision for an emissions value occurring at or near the method detection level is in fact about 40 to 50 percent. This large measure of analytic uncertainty decreases as measured values increase: Pollutant measurement imprecision decreases to a consistent relative 10 to 15 percent for values measured at a level about three times the method detection level.

See

American Society of Mechanical Engineers,

Reference Method Accuracy and Precision (ReMAP): Phase 1, Precision of Manual Stack Emission Measurements,

CRTD Vol. 60, February 2001. Thus, if the value equal to three times the representative method detection level were greater than the calculated floor emissions limit, we would conclude that the calculated floor emissions limit does not account entirely for measurement variability.

Memorandum. EPA Method 321 Detection Limits and Minimum Quantification Limit, July 26, 2010.

That is the case here with HCl. The calculated standard (not accounting for the inherent analytical variability in the measurements) is 0.52 ppm (

see

Table 7 above). In order to account for measurement variability, we multiplied the highest reported minimum detection level for the analytic method by a factor of three which results in a level of 0.9 ppmv. This represents the lowest level that can be reliably measured using this test method, and we therefore believe that it is the lowest level we can set as the MACT limit taking the appropriate measurement variability into account. Converting this level to a dry basis at 7 percent oxygen results in a floor of 3 ppmvd for both new and existing sources. As explained further below, we are using a CEM to measure this standard, and it is a 30-day average.

ii. Beyond the Floor Determination.

At proposal we examined the use of a packed bed scrubber, which was assumed to have a higher HCl removal efficiency than the spray tower limestone scrubbers typically used in this industry. Considering the high costs, high cost-effectiveness and small additional emissions reduction (and adverse cross-media impacts), we did not believe that a beyond-the-floor standard for HCl is justified. We received no comment that would change that decision. In addition, the current HCl floor limit is actually set at the lowest level we believe can be accurately quantified by the applicable test method. Therefore, a lower standard could not be reliably quantified. For these reasons we selected the floor level of control as MACT for HCl for major sources.

iii. Compliance Mechanisms.

As proposed, kilns equipped with wet scrubbers may demonstrate compliance by means of stack testing at intervals of 30 months, plus utilize continuous monitoring of specified parameters. All other kilns are required to use a CEMS, with compliance based on a 30-day rolling average. Although the underlying data were obtained via stack tests, rather than with continuous monitors, EPA believes that because the HCl standard is established at a level higher than all measured values (to account for the inability to reliably measure any lower standard) and measured based on 30-day averages, it provides an ample compliance margin.

iv. Determination not to Establish a Risk-Based Standard for HCl.

At proposal, EPA elected not to exercise its discretion under CAA section 112(d)(4) and proposed a major source standard for HCl based on MACT. The primary basis for not setting a health-based standard was that setting a MACT standard for HCl not only controlled HCl but also co-controlled other HAP (such as HF, Chlorine (Cl

), and hydrogen cyanide (HCN)) and criteria pollutants yielding very substantial environmental benefits. However, we also requested comment on whether we had the legal authority to establish a standard for HCl, and, if so, whether we should exercise our discretion to do so. 74 FR at 21154. After considering comments, EPA has decided not to exercise its discretion to establish a risk-based standard for HCl under CAA section 112(d)(4), opting instead to promulgate a standard for HCl based on the performance of MACT in this final rule. This section discusses the basis for that decision.

Setting technology-based MACT standards for HCl will result in significant reductions in emissions of other pollutants, most notably SO

, and would likely also result in additional reductions in emissions of mercury, along with condensable PM, ammonia, and semi-volatile compounds. The additional reductions of SO

alone attributable to the MACT standard for HCl are estimated to be 124,000 tons per year in the third year following promulgation of the proposed HCl standard. These are substantial reductions with substantial public health benefits. SO

emissions are associated with a variety of human health, ecosystem, and visibility effects. 75 FR at 35525-27 (June 22, 2010). Even more significantly, SO

is also a precursor to PM

2.5

. Reducing SO

emissions also reduces PM

2.5

formation, human exposure, and the incidence of PM

2.5

-related health effects, among them premature mortality and cardiovascular and respiratory morbidity.

See

detailed discussion of PM

2.5

health effects in the text at Table 13 below.

For these rules the SO

reductions represent a large fraction of the total monetized benefits from reducing PM

2.5

, but it is not possible to isolate the portion if the total monetized benefits attributable to the emission reductions of SO

resulting from the application of HCl controls. The benefits models assume that all fine particles, regardless of their chemical composition, are equally potent in causing premature mortality because there is no clear scientific evidence that would support the development of differential effects estimates by particle type.

We estimate the number of premature mortalities avoided each year due to the reductions in PM

2.5

exposure attributable to this standard to be in the thousands. RIA Table 6-3. We also estimate there to be over 2800 instances of annual cardiovascular and respiratory morbidity cases avoided, and hundreds of thousands of work loss days avoided.

Id.

The monetized benefits just from premature mortality avoided attributable to PM

2.5

reductions from this standard are estimated to be $7.4 billion to $18 billion at the three percent discount rate and $6.7 billion to $17 billion at a seven percent discount rate, nearly an order of magnitude higher than the rule's estimated social costs.

See

Table 13 below. Although MACT standards may directly regulate only HAPs and not criteria pollutants, Congress did recognize, in the legislative history to section 112(d)(4), that MACT standards would have the collateral benefit of controlling criteria pollutants as well and viewed this as an important benefit of the air toxics program.

The EPA believes these health and environmental benefits to be large and important and fully in keeping with the paramount goal of the Clean Air Act “to protect and enhance the quality of the Nation's air” (CAA section 101(b)(1)), and so is adopting MACT standards for HCl.

See

S. Rep. No. 101-228, 101st Cong. 1st sess. at 172. EPA consequently does not accept the argument that it cannot consider reductions of criteria pollutants in determining whether to exercise its discretion to adopt a risk-based standard under section 112(d)(4). There appears to be no valid reason that EPA must ignore controls which further the health and environmental outcomes at which section 112(d) of the Act is fundamentally aimed.

We further note that HCl is not the only acid gas HAP emitted by Portland cement plants. Hydrogen fluoride, HCN, ammonia, and chlorine may also present and were not accounted for in the risk analysis. Setting an HCl standard under 112(d)(2) and (3) allows the Agency to also address these other HAPs as they are co-controlled by wet scrubbers along with HCl.

Commenters from industry urged EPA to retain a risk-based standard but did not challenge EPA's finding or quantification that there would be these enormous health and environmental benefits to setting a standard reflecting MACT to control HCl. The commenters nonetheless urged EPA to retain a risk-based standard, noting that EPA had done so in the predecessor to this rule and for other source categories, and that HCl is a threshold pollutant within the meaning of CAA section 112(d)(4) so that there is a technical basis for such a standard. These arguments do not persuade the Agency to forego the very significant benefits just outlined. However, even if (contrary to the analysis just set out) EPA were inclined to adopt a risk-based standard here, there would be technical obstacles to doing so, as described at the final part of this section.

As we noted in the proposed rule, as a general matter, CAA section 112(d) requires MACT standards at least as stringent as the MACT floor to be set for all HAP emitted from major sources. However, CAA section 112(d)(4) provides that for HAP with established health thresholds, EPA has the discretionary authority to consider such health thresholds with an ample margin of safety when establishing emission standards under CAA section 112(d). This provision is intended to allow EPA to establish emission standards other than technology-based MACT standards in cases where a less stringent emission standard will still ensure that the health threshold will not be exceeded, with an ample margin of safety. In order to exercise this discretion, EPA must first conclude that the HAP at issue has an established health threshold and must then provide for an ample margin of safety when considering the health threshold to set an emission standard. We discussed this issue at length in the recent proposed Industrial Boiler MACT.

See

75 FR at 32020-33 (June 4, 2010) (declining to propose a risk-based standard for HCl emissions).

The legislative history of section 112(d)(4) indicates that Congress did not intend for this provision to provide a mechanism for EPA to delay issuance of emission standards for sources of HAPs. The legislative history also indicates that a health-based emission limit under section 112(d)(4) should be set at the level at which no observable effects occur, with an ample margin of safety. S. Rep. 101-228 at 171-72. The legislative history further states that employing a section 112(d)(4) standard rather than a conventional MACT standard “shall not result in adverse environmental effects which would otherwise be reduced or eliminated.”

Id.

It is clear that EPA may exercise its discretionary authority under 112(d)(4) only with respect to pollutants with an established health threshold. Where there is an established threshold, EPA has, in the proposed rule on industrial boilers, interpreted section 112(d)(4) to allow us to weigh additional factors, beyond any established health threshold, in making a judgment whether to set a standard for a specific pollutant based on the threshold, or instead follow the traditional path of developing a MACT standard after determining a MACT floor (75 FR 32030). In deciding whether to exercise its discretion for a threshold pollutant for a given source category, EPA has interpreted section 112(d)(4) to allow us to take into account factors such as the following: The potential for cumulative adverse health effects due to concurrent exposure to other HAPs with similar biological endpoints, from either the same or other source categories, where the concentration of the threshold pollutant emitted from the given source category is below the threshold; the potential impacts on ecosystems of releases of the pollutant; and reductions in criteria pollutant emissions and other co-benefits that would be achieved via the MACT standard—the decisive factor here. Each of these factors is directly relevant to the health and environmental outcomes at which section 112 of the Clean Air Act is fundamentally aimed. If EPA does determine that it is appropriate to set a standard based on a health threshold, we must develop emission standards that will ensure the public will not be exposed to levels of the pertinent HAP in excess of the health threshold, with an ample margin of safety.

Since any emission standard under section 112(d)(4) must consider the established health threshold level, with an ample margin of safety, in this rulemaking EPA has considered the adverse health effects of the HAP acid gases, beginning with HCl. Research indicates that HCl is associated with chronic respiratory toxicity. In the case of HCl, this means that chronic inhalation of HCl can cause tissue damage in humans. Among other things, it is corrosive to mucous membranes and can cause damage to eyes, nose, throat, and the upper respiratory tract as well as pulmonary edema, bronchitis, gastritis, and dermatitis. Considering this respiratory toxicity, EPA has established a chronic reference concentration (RfC) for the inhalation of HCl of 20 μg/m

. (

See http://www.epa.gov/ncea/iris/subst/0396.htm.

) An RfC is defined as an estimate (with uncertainty spanning perhaps an order of magnitude) of a continuous inhalation exposure to the human population (including sensitive subgroups

) that is likely to be without an appreciable risk of deleterious effects during a lifetime. The IRIS health assessment evaluated chronic non-cancer risks and did not include an evaluation of carcinogenic effects (on which there are very limited studies). As a reference value for a single pollutant, RfCs do not reflect any

potential cumulative or synergistic effects of an individual's exposure to multiple HAPs or to a combination of HAPs and criteria pollutants. Similarly, an RfC evaluation does not focus on potential environmental impacts.

“Sensitive subgroups” may refer to particular life stages, such as children or the elderly, or to those with particular medical conditions, such as asthmatics.

With respect to the potential health effects of HCl, we know the following:

1. Chronic exposure to concentrations at or below the RfC is not expected to cause chronic respiratory effects;

2. Little research has been conducted on its carcinogenicity. The one occupational study of which we are aware found no evidence of carcinogenicity;

3. There is a significant body of scientific literature addressing the health effects of acute exposure to HCl (California Office of Health Hazard Assessment, 2008. Acute Toxicity Summary for Hydrogen Chloride,

http://www.oehha.ca.gov/air/hot_spots/2008/AppendixD2_final.pdf#page=112

EPA, 2001). However, we currently lack information on the peak short-term emissions of HCl from cement kilns which might allow us to determine whether a chronic health-based emission standard for HCl would ensure that acute exposures will not pose health concerns.

4. We are aware of no studies explicitly addressing the toxicity of mixtures of HCl with other respiratory irritants. However, many of the other HAPs (and criteria pollutants) emitted by cement kilns also are respiratory irritants, and in the absence of information on interactions, EPA assumes an additive cumulative effect (Supplementary Guidance for Conducting Health Risk Assessment of Chemical Mixtures.

http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=20533

Cement kilns also emit other acid gases along with HCl, including chlorine (Cl

), HCN and hydrogen fluoride (HF), all of which are HAPs. Like HCl, these HAP gases have established chronic health thresholds below which they are not expected to pose any significant risk of chronic respiratory effects, have no evidence to suggest that they may pose carcinogenic effects, and have an established body of literature regarding acute respiratory health effects. They are also controlled during the process of controlling HCl emissions from cement kilns using a wet scrubber. As such, their health impacts must be taken into account when considering a health-based emission limit for HCl.

In the 2006 final rule, EPA did not set any standard for HCl.

The Agency reasoned that no further control was necessary for Portland cement emissions of HCl because HCl is a “health threshold pollutant” and human health is protected with an ample margin of safety at current HCl emission levels. 71 FR at 76527. Underlying this conclusion was EPA's analysis of a tiered screening study of dispersion modeling of cement facilities' worst-case and actual HCl emissions. This study was conducted by the Portland Cement Association for about two-thirds of operating U.S. cement plants. Dispersion modeling results were evaluated against the RfC for HCl.

The screening analysis involved making conservative assumptions regarding HCl emission concentrations and plants' operating conditions (greater concentrations than known to be emitted and perpetual operation at maximum capacity). All plants in the analysis, with five exceptions, had HCl levels well below a Hazard Quotient (HQ) level of 1.0, the ratio of exposure (or modeled concentration) to the health reference value or threshold level. The remaining five plants in the analysis had HQ levels greater than 1.0 assuming maximum emissions, but less than 1.0 when their actual emissions were used in the dispersion models.

Id.

at 76528-29.

Although the decision not to set a standard in 2006 was based on the authority of section 112(d)(4), we note that the statute in fact states: “the Administrator may consider such threshold level, with an ample margin of safety,

when establishing emission standards

under this subsection.” Section 112(d)(4), emphasis added.

In the previous study EPA also evaluated dispersion modeling results against an acute exposure guideline level (AEGL) below which acute effects would not be expected to occur. However, even given the uncertainties mentioned for short term HCl emissions, that analysis indicated that chronic effects would be of the most concern.

At proposal of these amendments, recognizing that the 2006 determination was deficient, if for no other reason because it failed to establish any emission standard whatever, EPA conducted its own analysis to determine what numerical standard for HCl would be necessary to at least assure that, for the sources in the controlled category or subcategory, persons exposed to emissions of HCl would not experience the adverse health effects on which the threshold is based. In order to determine this level, in the proposed rule we conducted a risk analysis of the same 68 facilities analyzed by PCA using a screening level dispersion model (AERSCREEN). Using the site specific stack parameters provided by the PCA and conservative meteorological conditions (taken from the PCA analysis), the AERSCREEN modeling predicted the highest long term ground level concentration surrounding each facility, and used this concentration to back calculate the highest allowable HCl emissions rate that could occur without exceeding the allowable RfC. The results of this analysis indicated that an HCl emission limit of 23 ppmv or less (an order of magnitude higher than the MACT standard) would result in no exceedances of the RfC for HCl for any of the facilities assessed.

Derivation of a Health-Based Stack Gas Concentration Limit for HCl in Support of the National Emission Standards for Hazardous Air Pollutants from the Portland Cement Manufacturing Industry, April 10, 2009.

Based on further consideration, EPA now believes that the 2006 PCA study and analysis has the following deficiencies. First of all, not all cement plants were evaluated (the PCA study covered about two thirds of the plants in the source category), and among those not evaluated were cement plants with the most likelihood of posing risk at ground level from HCl emissions due to use of positive pressure baghouses with monovents or multiple short stacks. Secondly, the analysis did not consider the impacts of the co-emitted acid gases, an important consideration in determining an ample margin of safety. In addition, no data were provided, nor do we have data, on other pollutants in the vicinity of these cement facilities, or background concentration data for HCl to determine cumulative impacts of HCl emissions for these facilities.

EPA's analysis of 2009 could not improve on the PCA study, given the lack of robust emissions data for Cl

, HF, and HCN, and the lack of any additional data for the cement kilns not included in the original study. As a result, EPA cannot ensure that the resulting derivation of 23 ppmv as a possible health-based emission standard for HCl would result in chronic ambient levels of acid gases that would not pose significant health risks. EPA has no data that would allow us to extend that analysis to cover all acid gases and all facilities.

It should be noted that large amounts of site-specific information both on kiln operation and local meteorological information is needed to obtain meaningful results from AERSCREEN and other dispersion models. This information is in the ready possession of the industrial sources themselves, but for unknown reasons, was not provided by industry to EPA either as part of the 2006 PCA analysis or in response to subsequent data solicitations by EPA.

In addition to potential health impacts, EPA has evaluated the potential for environmental impacts when considering whether to exercise discretion under section 112(d)(4). When HCl gas encounters water in the

atmosphere, it forms an acidic solution of HCl. In areas where the deposition of acids derived from emissions of sulfur and nitrogen oxides are causing aquatic and/or terrestrial acidification, with accompanying ecological impacts, the deposition of HCl could exacerbate these impacts. Being mindful of the explicit legislative history, and in keeping with past EPA practice, it is appropriate to consider potential adverse environmental effects in addition to adverse health effects when setting an emission standard for HCl under section 112(d)(4). The co-emissions of HF, HCN, and Cl

from cement kilns could serve to further aggravate these environmental acidification impacts, but EPA has no data to determine these impacts.

Although the PCA analysis did not include an assessment of potential environmental effects, for the 2006 final Portland cement rule, EPA conducted its own analysis of potential effects of cement kilns' HCl emissions to wildlife, aquatic life, and other natural resources. The Agency concluded at the time that acute and chronic exposures to expected HCl concentration around cement kilns are not expected to result in adverse environmental toxicity effects.

Id.

at 76529. EPA accordingly declined to establish any standard for HCl.

At this time, we now believe the ecological risk analysis performed in 2006 is insufficient, as it was merely a literature review and not a formal ecological assessment, and, as discussed in the previous paragraphs, it did not cover the impacts of the other acid gases, nor did it cover about one third of the existing cement plants. No additional information was provided during the comment period which addressed these various technical issues, notwithstanding EPA's solicitation of data.

Consequently, although EPA is declining to adopt a section 112(d)(4) risk-based standard for HCl emissions from Portland cement facilities for the sound policy reasons discussed herein, we further note that there remain technical issues as to the appropriateness of such a standard even if EPA were inclined to exercise that discretion. We also do not view ourselves as bound by the technical determinations made in the 2006 rulemaking for the reasons just explained.

EPA also has concluded that the facts here are distinguishable from those in other rulemakings in which it exercised its discretionary authority under section 112(d)(4). In the case of the Pulp and Paper MACT (63 FR at 18765 (April 15, 1998)), the risk analysis indicated, at the 95 percent confidence interval, that the maximum concentration predicted to which people were estimated to be exposed was 0.3 g/m

, 60 times less than the inhalation reference concentration. This is a much lower value than present in the Portland cement risk analysis discussed above. In the case of the Lime Manufacturing NESHAP (67 FR at 78054 (Dec. 20, 2002)), there are two key distinctions. First, the technical information available to EPA covered 100 percent of all lime kilns in the U.S., which is not the case for the Portland cement risk analysis. Second, EPA did a worst case analysis as a supplement to the industry analysis and determined that the highest hazard index under that scenario was 0.21. Based on the EPA analysis determining a health based limit for Portland cement, if we were to allow the same level of risk as we determined in Lime NESHAP analysis, the health based emission limit would be 2 ppmvd, which is almost the same level as the MACT standard we are finalizing in this action.

EPA also considers the alternative standard for total chlorine in the Hazardous Waste Combustor MACT (70 FR at 59555 (Oct. 12, 2005)) to be distinguishable. That rule, under the authority of section 112(d)(4) establishes a site-specific risk-based standard for total chlorine (of which HCl is the largest component), whereby, in lieu of meeting the MACT standard, sources may emit total chlorine at higher levels if they demonstrate that their emissions of total chlorine from all hazardous waste combustor sources at a facility do not exceed both acute (one-hour) and chronic (annual) exposure thresholds. The demonstration must account for all relevant site-specific conditions, or be based on worst-case screening assumptions. If sources satisfy these criteria, the amount of their total chlorine emissions is still capped by the technology-based limit to which these sources were previously subject. The site-specific demonstrations, applicability to all combustor sources at a facility, use of acute and chronic health benchmarks, and capping of emission limits are all unique to that rule.

e. PM Emissions From Kilns

Particulate matter serves as a surrogate for non-volatile metal HAP (a determination upheld for this source category in

National Lime Ass'n,

233 F. 3d at 637-39). Existing and new major sources are presently subject to a PM limit of 0.3 lb/ton of feed which is equivalent to 0.5 lb/ton clinker. EPA is amending this standard for major sources, and also adding PM standards for existing and new area source cement kilns. In all instances, EPA is revising these limits because they do not represent MACT, but rather a level which is achievable by the bulk of the industry.

See

63 FR at 14198 (March 24, 1998);

see also

233 F. 3d at 633 (indicating that the standards for PM were likely legally deficient but that the argument had not been properly preserved for the court to adjudicate). This is not legally permissible.

Brick MACT,

479 F. 3d at 880-81. EPA thus does not accept the argument of some commenters that EPA may only amend promulgated MACT standards by means of the periodic review procedures of section 112(d)(6), which does not include re-determining floor levels. Section 112(d)(6)does not indicate that it is the exclusive means of amending MACT standards, and in particular does not speak to a situation where an original floor was palpably short of statutory requirements and where that floor became the ultimate standard. EPA consequently believes it has discretion to reconsider and redo the MACT floor analysis for PM, and to amend the standard as appropriate.

Other commenters suggested that even if EPA has such discretion, it would (or should) be limited to a reanalysis of the original database for the 1999 rule and so should not consider kilns' subsequent performance. Were EPA to take that approach here, the floor (and standard) for PM would be more stringent than the floor (and standard) in this rule.

Because EPA considers the database for the current rule to be more representative of performance capabilities of best performing kilns than the sparser 1999 database, EPA is basing its determination on the more representative data.

Calculation of PM MACT Floor Based on Data in 1998 Proposal. July 7, 2010.

EPA is setting a PM standard based on MACT for existing and new area source cement kilns. As noted at proposal, Portland cement kilns are a listed area source category for urban HAP metals pursuant to section 112(c)(3), and control of these metal HAP emissions (via the standard for the PM metal surrogate) is required to ensure that area sources representing 90 percent of the area source emissions of urban metal HAP are subject to section 112 control, as required by section 112(c)(3). EPA has determined that this standard should reflect MACT, rather than GACT, because there is no essential difference between area source and major source cement kilns with respect to emissions

of either HAP metals or PM. Thus, the factors that determine whether a cement kiln is major or area are typically a function of the source's HCl or formaldehyde emissions, rather than its emissions of HAP metals. As a result, there are kilns that are physically quite large that are area sources, and kilns that are small that are major sources. Both large and small kilns have similar HAP metal and PM emissions characteristics and controls.

Given that EPA is developing major and area source standards for PM at the same time in this rulemaking, a common control strategy consequently appears warranted for these emissions. We thus have included all cement kilns in the floor calculations for the final PM standard, and have developed common PM limits based on MACT for both major and area sources.

Floor Determination.

At proposal we had compiled PM stack test data for 45 kilns from the period 1998 to 2007. EPA ranked the data by emissions level and the lowest emitting 12 percent, 6 kilns, was used to develop the proposed existing source MACT floors of 0.085 and 0.08 lb/ton clinker for new and existing sources respectively.

Commenters noted that we had omitted some of the data already submitted to EPA in developing the MACT floor. In addition, we noted for two of the best performing facilities we had only one emissions test. Therefore we requested these sources to submit additional PM emission test data and the source sent two additional PM emissions tests for each kiln to allow us to better characterize emissions variability. We modified the PM data base to reflect these submissions. Another change made since proposal is that we have changed the compliance requirement to require a PM CEMS. This requires that we establish an averaging period. We chose a period of 30 days (rolling average) to be consistent with requirements for mercury and THC, and because PM emissions on a lb/ton basis are affected by raw mill cycles (typically encompassed within 30-days,

see

74 FR at 21144) for kilns with in-line raw mills. We have converted the concentrations obtained from 3-hour tests into 30-day values by means of the UPL equation previously described. It should be noted that due to the longer averaging periods, the actual limit will be a lower number compared to the shorter compliance interval in the proposed rule (30 days versus a three hour test). This damping of variability when a longer averaging period is used is well established where continuous monitors have been used to measure emissions, and is also accounted for in the “m” term of the UPL equation. The results of the new MACT analysis are shown in Table 8.

Table 8—PM MACT Floor

Kiln

PM emissions (lb/ton clinker)

0.01

0.03

0.04

MACT—Existing

Average

0.02

Variance

0.001

UPL

0.04

MACT—New

Average

0.01

Variance

0.00001

UPL

0.01

EPA proposed use of PM CEMS as an alternative to using a bag leak detector, and also solicited comment on requiring their use generally. 74 FR at 21157. As we noted there, performance specifications for PM CEMS are now available, and continuous monitors “give a far better measure of sources' performance over time than periodic stack tests”. After considering the public comments, EPA continues to believe that this is the case.

See also

further discussion of this issue at Section A.3 of this preamble below.

EPA does not agree with the comment that use of a CEM renders the standard more stringent and so results in floors (and standards) more stringent than those achieved by average of the best performing sources. First, the continuous collection of data used to assess compliance with this standard does not create a limit more stringent that otherwise allowed. As discussed in the preamble to the Credible Evidence Rule, “* * * continuous monitoring of the standards (has) no effect on the stringency of the standard * * * ” (62 FR at 8326, February 24, 1997).

Further, a statistically-based adjustment to account for emissions variability, and which, in this case, increases the numerical value of the standard (and its longer averaging period) by fifty percent, does not make the standard more stringent. Finally, increasing the averaging period beyond the duration associated with conducting a performance test (typically three hours) to 30 days normally makes a standard more lenient because there is more opportunity to average out individual results. As mentioned in the description of the Salo and Pederson memoranda cited in Section 4.1.2.1 of the Credible Evidence Rule Response to Comment Document, “* * * (t)he effect of the change from a 3-hour averaging time to a 30-day averaging time is to make the standard more lenient * * * ”.

Available at

http://www.epa.gov/ttncaaa1/t1/fr_notices/certcfin.pdf.

ii. Beyond the Floor Determination

EPA did not propose beyond-the-floor standards for PM. This was because the cost effectiveness of adopting beyond-the-floor controls was several orders of magnitude greater than EPA has accepted for PM reductions in other rules where standards allow consideration of costs, and because the incremental amount of PM removed was very small (3 tpy nationwide). Consideration of non-air quality issues did not change this conclusion. 74 FR at 21155. Commenters did not challenge this analysis. EPA accordingly is not adopting beyond-the-floor standards for PM.

The final PM emissions limit for existing sources is 0.04 pounds per ton (lb/ton) clinker for and 0.01 lb/tons clinker for new sources (30-day average). Kilns where the clinker cooler gas is combined with the kiln exhaust and sent to a single control device for energy efficiency purposes (

i.e.,

to extract heat from the clinker cooler exhaust) will be allowed to adjust the PM standard to an equivalent level accounting for the increased gas flow due to combining of kiln and clinker cooler exhaust (an action for which EPA received no adverse comment).

See

74 FR at 21156 and 73 FR at 64090-91 (Oct. 28, 2008) (explaining the equivalency of this standard and the energy efficiency benefits resulting from combining these gas flows). The PM standard is a 30-day rolling average and is measured with a CEM.

iii. Compliance Alternative for Comingled Kiln/Clinker Cooler Exhaust.

As we noted at proposal, some kilns combine the clinker cooler gas with the kiln exhaust and send the combined emissions to a single control device. There are significant energy savings (and attendant greenhouse gas emission reductions) associated with this practice, since heat can be extracted from the clinker cooler exhaust. However, there need to be different conversion factors from concentration to mass per unit clinker in these cases to allow for the increased gas flow, which result in a different PM emissions limit. We proposed adjustment factors that would account for these differences and create a site specific PM emission limit

of this situation.

See

74 FR 21155-56 and 21184. We received no comments on these factors and are thus adopting them as proposed, except that the factors have been changed to account for changes in the underlying kiln and clinker cooler emissions limits. Note that adjustments would also be necessary for kilns subject to the NSPS PM limit. Thus, we are including a cross reference for the NSPS to the appropriate section of the NESHAP rule.

f. Opacity Standards for Kilns and Clinker Coolers

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. Although some commenters requested retention of opacity as a backup standard, and others as an alternative, none of these comments offered any convincing information or other justification for perpetuating a less reliable compliance methodology. Though we have preserved some regulation text, any kiln or clinker cooler that uses a PM CEMS to monitor compliance with the PM emission limit is exempt from opacity standards.

g. PM Standard for Clinker Coolers

In addition to amending the PM standard for kilns we are similarly amending the PM emissions limit for clinker coolers. Fabric filters are the usual control for both cement kilns and clinker coolers. As EPA noted in our proposed revision to the NSPS (73 FR 34078, June 16, 2008), we believe that the current clinker cooler controls can meet the same level of PM control that can be met by the cement kiln. No commenter challenged this. One commenter did state that PM limits for clinker coolers should not be changed, but we disagree with that comment for the reasons previously discussed on the PM limit for kilns. Therefore, we are setting the same PM emissions limits and compliance requirements for both clinker coolers and kilns.

h. Standards for Open Clinker Piles

At proposal we noted that open clinker piles were currently unregulated, and that hexavalent chromium emissions had been detected in fugitive dust from these piles.

See

74 FR at 21163. We requested comment and information as to how common the practice of open clinker storage is, appropriate ways to detect or measure fugitive emissions (ranging from open-path techniques to continuous digital or intermittent manual visible emissions techniques), any measurements of emissions of hexavalent chromium (or other HAP) from these open storage piles, potential controls to reduce emissions, or any other factors we should consider.

Commenters did not provide data on this practice. Industry commenters stated emission were

de minimis

and should not be regulated. Other commenters noted that the fact that we know these sources emit HAP is sufficient to necessitate regulation.

We agree that these operations do emit HAP and that regulation of these sources is necessary.

See National Lime,

233 F. 3d at 640 (upholding EPA position that de minimis exceptions are not to be read into the MACT standard setting process). Because the emissions in question are fugitive dust for which measurement is not feasible since (by definition) the emissions are not emitted through a conveyance or other device which allows their measurement (

see

section 112 (h)(1) and (2)(A)), we are adopting the work practice standards and opacity emissions limits contained in Rule 1156 as amended by the South Coast Air Quality Management District on March 6, 2009 and incorporating them into this rule. There are only two plants which EPA can state definitively have open storage piles and are complying with Rule 1156, so these existing regulatory standards would constitute a floor level of control (and EPA does not believe beyond-the-floor controls are needed, since utilizing some type of enclosure should well control fugitive emissions). A summary of the requirements are as follows:

If clinker material storage and handling activities occur more than 1,000 feet from the facility property-line,

○ Utilize a three-sided barrier with roof, provided the open side is covered with a wind fence material of a maximum 20 percent porosity, allowing a removable opening for vehicle access. The removable wind fence for vehicle access may be removed only during minor or routine maintenance activities, the creation or reclamation of outside storage piles, the importation of clinker from outside the facility, and reclamation of plant clean-up materials. The removable opening shall be less than 50 percent of the total surface area of the wind fence and the amount of time shall be minimized to the extent feasible;

○ Storage and handling of material that is immediately adjacent to the three-sided barrier due to space limitations inside the structure shall be contained within an area next to the structure with a wind fence on at least two sides, with at least a 5 foot freeboard above the top of the storage pile to provide wind sheltering, and shall be completely covered with an impervious tarp, revealing only the active disturbed portion during material loading and unloading activities;

○ Storage and handling of other active clinker material shall be conducted within an area surrounded on three sides by a barrier or wind fences with one side of the wind fence facing the prevailing wind and at least a 5-foot freeboard above the top of the storage pile to provide wind sheltering. The clinker shall remain completely covered at all times with an impervious tarp, revealing only the active disturbed portion during material loading and unloading activities. The barrier or wind fence shall extend at least 20 feet beyond the active portion of the material at all times; and

○ Inactive clinker material may be alternatively stored using a continuous and impervious tarp, covered at all times, provided records are kept demonstrating the inactive status of such stored material.

• If clinker material storage and handling activities occur 1,000 feet or less from the facility property-line these activities must be in an enclosed storage area.

In the SCAQMD regulation, there are different requirements for active vs. inactive open clinker piles. An inactive pile is one that had not been disturbed for 30 consecutive days. In addition, the ACAQMD rule has different requirements for clinker piles that are 1,000 feet or less form the facility property-line. This 1000 foot criterion was a mutually agreed number among the stakeholders (both industry and environmental groups) involved in developing the regulation.

Given the lack of additional data, we saw no reason to change these criterion. More information on this rule is available at

http://www.aqmd.gov/hb/gb_cal95.html.

Telecon with Tuyet-Le Pham, South Coast Air Quality Management District. June 29, 2010.

Industry commenters also maintained that regulation of open storage piles would violate a 2001 settlement agreement between EPA and the industry in which EPA agreed that the 1999 rule did not apply to fugitive emission sources. But nothing in that settlement agreement prevents EPA from amending its regulations if it is appropriate to do so (nor could EPA legally bind itself in such a way). The agreement in fact states that “[n]othing in this Agreement shall be construed to limit or modify EPA's discretion to alter, amend, or revise, or to promulgate regulations that supersede, the

regulations identified in section III of this Agreement.” Consequently, EPA's action today properly amends the current regulation, and does not violate any provisions of the settlement agreement.

i. Format of the Normalized Standards in the NESHAP and the NSPS

Emission limits are typically normalized to some type of production or raw material input value because this allows comparison (and ultimately the ability to set a single standard) for different sized facilities. As we noted at the NSPS proposal, the current NSPS and limits (and NESHAP limits before today's amendments) for PM are expressed on a pound of PM per ton (lb/ton) of dry feed input format.

See

73 FR at 34075-76. In this final NESHAP (and NSPS) we are adopting a new normalizing parameter of lb/ton of clinker—

i.e.,

normalizing based on kiln output rather than input for both PM and mercury.

We noted at proposal of the NSPS that adopting an output-based standard avoids rewarding a source for becoming less efficient,

i.e.,

requiring more feed to produce a unit of product, therefore promoting the most efficient production processes. 73 FR at 34076. EPA therefore proposed that all of the NSPS (for PM, NO

, and SO

) be normalized by ton of clinker produced, and later proposed the same parameter for the two standards in the NESHAP which are normalized, mercury and PM. 73 FR at 34076; 74 FR at 21140.

In this final NESHAP (and NSPS) we are therefore adopting a new normalizing parameter of lb/ton of clinker—

i.e.

normalizing based on kiln output rather than input—for mercury and PM in the NESHAP, and for PM, NO

, and SO

in the NSPS. Commenters either supported this proposal, or did not question that normalizing by output promotes more efficient production. However, commenters from industry raised technical objections and concerns to the proposal. They maintained that the measurement of kiln output is not as exact as the measurement of kiln input, and that many kilns have not installed clinker measuring equipment. These objections do not necessitate normalizing by inputs. Most commenters also stated that kiln feed could be accurately measured and also indicated that most facilities currently derive reasonable feed-to-clinker conversion factors from these measurements. Kilns already calculate clinker production in this way when required to meet emissions limits normalized by clinker production, as many NSR and PSD permits for cement kilns presently do.

RACT/BACT/LAER Clearing house Report for Portland Cement. November 25, 2009.

Since it appears from comments that the equipment to accurately measure clinker is not typically installed in this industry, we must assume these facilities use a feed-to-clinker conversion factor to calculate clinker production on whatever time basis is necessary (

e.g.,

daily, hourly,

etc.

). Therefore, we have modified the rule language to more clearly provide the option allowing facilities to measure feed inputs and to use their site specific feed/clinker ratio to calculate clinker production (and to make clear that no prior approval from a regulatory authority is necessary to do so). Facilities would be allowed to use a constant feed/clinker ratio in accord with their usual cycles for determining such ratios, typically on a monthly basis when clinker inventories are reconciled.

Commenters were nonetheless concerned that because clinker/feed ratios change somewhat and are only re-determined at the end of a cycle, a slight change in clinker/feed ratio, determined at the end of the cycle, could show lack of compliance without even an opportunity to alter operation. To obviate this legitimate concern, the rule provides that facilities are not required to retroactively update clinker production estimates after recomputing feed/clinker ratios. We would not expect that the clinker/feed ratio will change significantly from month to month, so we do not see this as creating a situation where facilities will be able to have large amounts of excess emissions but still be considered in compliance (especially since the 30-day standards are all rolling averages).

So, for these reasons above we are adopting emission limits normalized by kiln output for PM in both the NESHAP and the NSPS, for mercury in the NESHAP, and for NO

and SO

in the NSPS (the same analysis applying to the limits in the NSPS).

2. What are the final operating limits under subpart LLL?

EPA is eliminating the restriction, adopted in the 2006 rule, on the use of fly ash where the mercury content of the fly ash has been increased through the use of activated carbon once the kiln has complied with a numerical mercury emissions limit. Given the emission limitation for mercury, whereby kilns must continuously meet the mercury emission limits described above (including when using these materials) there does not appear to be a need for such a provision. This provision is removed once a kiln is in compliance with the mercury limitations adopted in this. We are removing the requirement at compliance, rather than when the rule takes effect, to prevent the possibility of additional mercury emissions between the rule's effective date and the required compliance date. However, once the rule takes effect EPA is removing the requirement to maintain the amount of cement kiln dust wasted during testing of a control device, and the provision requiring that kilns remove from the kiln system sufficient amounts of dust so as not to impair product quality for the same reasons. In this case, we do not see immediate removal of these provisions as creating a likelihood of increased mercury emissions prior to the compliance date.

3. What are the final testing and monitoring requirements under subpart LLL?

Kilns will be required to meet the following changed monitoring/testing requirements:

• CEMS (PS-12A) or sorbent trap monitors (PS-12B) to continuously measure mercury emissions, along with Procedure 5 for ongoing quality assurance.

• CEMS meeting the requirement of PS-8 to measure THC emissions for existing sources. (New sources are already required to monitor THC with such a CEMS). Kilns meeting the organic HAP alternative to the THC limit will still be required to continuously monitor THC (based on the results of THC monitoring done concurrently with the Method 320 test), and will also be required to test emissions using EPA Method 320 or ASTM D6348-03 every 30 months to identify the organic HAP component of their THC emissions.

• Installation and operation of a PM CEMS that meets the requirements of PS-11.

• CEMS meeting the requirements of PS-15 will be required to demonstrate compliance with the HCl standard for all kilns except those using a caustic scrubber. If a facility is using a caustic scrubber to meet the standard, EPA Test Method 321 and ongoing continuous parameter monitoring of the scrubber may be used in lieu of a CEMS to demonstrate compliance. The M321 test must be repeated every 30 months.

Raw material dryers that are existing sources will also be required to install and operate CEMS meeting the requirement of PS-8 to measure THC emissions. (New raw material dryer sources are already required to monitor THC with a CEMS). Raw material dryers

meeting the organic HAP alternative to the THC limit will still be required to continuously monitor THC (based on the results of THC monitoring done concurrently with the Method 320 test), and will also be required to test emissions using EPA Method 320 or ASTM D6348-03 every 30 months to identify the organic HAP component of their THC emissions.

New or reconstructed raw material dryers and raw or finish mills will be subject to longer Method 22 and, potentially, to longer Method 9 tests. The increase in test length duration is necessary to better reflect the operating characteristics of sources subject to the rule. EPA has included the costs associated with increased test duration in its estimates of the rule's costs.

The requirements above are the same as those proposed with the following exceptions.

For kilns and clinker coolers, EPA proposed to require bag leak detection systems for fabric filters and an ESP predictive model to monitor performance of an ESP. In this final rule we are requiring the use of a PM CEMS for all PM control devices. We did receive comments on technical issues associated with PM CEMS, which we have addressed in the Comments and Responses Document in the docket to this rulemaking. As explained earlier, we continue to believe that these devices provide the most positive indication that a facility is actually complying with the PM emissions limit. We also note that we promulgated a requirement for PM CEMS in the 1999 final rule but deferred the compliance date until the establishment of performance specifications. These specifications have now been established as EPA Performance Specification 11.

In the proposed rule we specified that THC CEMS must meet the requirements of performance specification 8A. Commenters correctly pointed out certain deficiencies of the 8A method as applied to this source category. In response to those comments we have changed the requirement to PS-8.

Where periodic performance tests are required for HCl we changed the test frequency to 30 months because a commenter noted both chlorine inputs and scrubber performance may change significantly over five years. For similar reasons we changed the testing frequency for the organic HAP option to 30 months. We believe aligning the test schedules for all pollutants (dioxin furan, organic HAP, and HCl) to the same testing schedule will allow for more efficient use of testing resources.

4. Standards for Startup and Shutdown

As noted above, the United States Court of Appeals for the District of Columbia Circuit vacated portions of two provisions in EPA's CAA section 112 regulations governing the emissions of HAP during periods of SSM.

Sierra Club

EPA,

551 F.3d 1019 (DC Cir. 2008),

cert. denied,

130 S. Ct. 1735 (U.S. 2010). Specifically, the Court vacated the SSM exemption contained in 40 CFR 63.6(f)(1) and 40 CFR 63.6(h)(1), that are part of a regulation, commonly referred to as the “General Provisions Rule,” that EPA promulgated under section 112 of the CAA. When incorporated into CAA section 112(d) regulations for specific source categories, these two provisions exempt sources from the requirement to comply with the otherwise applicable CAA section 112(d) emission standard during periods of SSM.

The effect of the vacatur is that the cross-reference to 40 CFR 63.6(f)(1) and 40 CFR 63.6(h)(1) in Table 2 to subpart LLL no longer operates to incorporate an SSM exemption.

In light of the

Sierra Club

decision, EPA proposed to require that sources be in continuous compliance with emissions limits at all times, even during startup, shutdown, and malfunction. 74 FR at 21161-62. We proposed that these sources meet the same standards at all times.

Id.

We also specifically asked for information on emissions during startup, shutdown, and malfunction.

In these final amendments we have eliminated the cross-reference to the vacated General Provisions' exemptions contained in Table 1 of current subpart LLL. In establishing the standards in this rule, EPA has taken into account cement kilns' operating properties during startup and shutdown periods and, for the reasons explained below, has established different standards for those periods. EPA is not setting separate standards for malfunctions so that, for the reasons explained below, the standard that applies during normal operations applies during periods of malfunctions. We have also revised Table 2 (the General Provisions table) in several respects. For example, we have eliminated the General Provisions' requirement that the source develop an SSM plan. We have also removed certain recordkeeping and reporting requirements related to the SSM exemption. EPA has attempted to ensure that we have not incorporated into the regulatory text any provisions that are inappropriate, unnecessary, or redundant in the absence of the SSM exemption.

Startup is the period of time between when fuel is first introduced into a cement kiln that is not firing fuel, and when the kiln temperatures are within normal operating limits, the kiln is using its normal operating fuel, and the kiln is producing clinker. During kiln startup, fuel is first introduced into the kiln to raise the kiln to the appropriate operating temperatures. In the case of a cold start the fuel is typically a natural gas or distillate fuel. Once the kiln reaches certain temperatures, the normal operation fuel is introduced. After the kiln reaches stable operating temperatures, kiln feed is introduced in low amounts which are gradually increased. Because the kiln feed is a significant source of most kiln emissions (HAP and otherwise) we would consequently expect that kiln emissions, on a concentration basis, would not be any higher during startup than during normal operations, with any potential short-term emission spikes due to transient conditions or release of emissions from materials left in the kiln from the last operating period being accommodated through an averaging period. Indeed, on a pure concentration basis, kiln emissions over time would likely be lower than during normal operation given the lesser volume of inputs being processed, and (at startup) the cleaner fuel being used to heat the kiln to normal operating conditions.

Notwithstanding that stack concentrations over time would likely be the same or less than during normal operation, in some cases, the manner in which the standard is expressed is not appropriate during startup. Most particularly, the mercury and PM standards are normalized to kiln production (amount of pollutant allowed being linked to a ton of clinker produced). During startup, production is by definition either non-existent or very low. Even where there is a modest amount of production during startup, relationships between HAP concentration and amount of product are skewed so as to make this means of measurement inappropriate. In addition, normalized standards require accurate measurements of kiln volumetric flow rate (used to convert concentration into mass) and kiln flow rate, which changes in important ways from normal values during startup. When considered along with such phenomena as varying kiln stack moisture contents and flow rate, flow rate measurements are significantly less accurate during startup than during normal operation.

For these reasons, we are establishing standards for mercury and PM by converting the normal operation standards to a concentration basis.

These conversions are as follows: 55 lb mercury/MM tons clinker is equivalent to 10 micrograms per dry standard cubic meter (ug/dscm); 21 lb mercury/MM tons clinker is equivalent to 4 ug/dscm; 0.04 lb PM/ton clinker is equivalent to 0.004 grains per dry standard cubic foot (gr/dscf); and 0.01 lb PM/ton clinker is equivalent to 0.0008 gr/dscf. Mercury and PM would be measured during startup with a CEMS (as during normal operation) and the concentration standard would be met on the basis of 7-day averages. We do not believe a 30-day average is appropriate for these periods because they are of short duration, and it might take a period of 1 year or more to accumulate 30 days of startup operation. We considered an averaging period equal to the time period of each startup, but that would have meant different averaging periods for each event. Therefore, we chose 7 days as a period short enough to accumulate the data necessary to calculate the average over a reasonable period (certainly less than a year) but long enough to allow averaging out any transient spikes that may occur. In this way, short-term spikes which occur during startup would be averaged against the lower concentrations which otherwise typically maintained. A consequence of this compliance regime (as for the standards which apply during normal operation), is that a source (at least initially) cannot determine compliance based on any single startup (or shutdown) event. Seven days of data will need to be averaged.

All of the discussion above applies to THC emissions during startup: Feed (the main source of THC emissions) is introduced gradually so THC emissions should ordinarily be lower, cleaner fuels are initially used to heat the kiln to normal temperatures,

etc.

The difference is that the THC standard is already expressed as a concentration, so the measurement difficulties with a normalized standard do not exist. However, during normal operation the THC standard is corrected to a specified oxygen concentration to avoid the situation where a facility uses dilution air to lower the measured concentration. At startup, oxygen concentrations may be higher than during normal operation, and may also fluctuate more. This could have the effect of actually making the standard more stringent during startup. Consequently, EPA is adopting the same concentration standard for THC during startup as applies during normal operation, but is removing the oxygen concentration correction factor. The standard is measured with a CEMS and is based on a 7-day average so, that, again the lower concentrations which ordinarily maintain at startup should balance out any transient events that occur because the kiln is not yet in steady state mode.

HCl is also expressed as an un-normalized stack concentration corrected to a specific oxygen concentration. Where measured with a CEMS, EPA knows of no reason the same standard as applies during normal operation should not be met during startup, except that the averaging period would be 7 days and the oxygen correction factor would be removed for the reasons noted above. However, for those units equipped with wet scrubbers, sources may choose to demonstrate compliance by means of stack testing and parametric monitoring.

See

Section IV.A.3. In such a circumstance, there are no parameters to measure because HCl will not be emitted. This is because HCl is emitted only as kilns begin burning normal fuel, not the natural gas or distillate used as a fuel during startup. Consequently, EPA is providing that emissions of HCl shall be zero at all such times as distillate or natural gas is used to fire the kiln (and that is the parameter which would be measured).

The current standard for dioxins and furans is expressed either as a concentration, or a combination of concentration and temperature control at the inlet to the PM control device. Continuous compliance is determined based on demonstrating the measured temperature at the inlet to the PM control device does not exceed the limit established during dioxin compliance testing. This is because higher PM control inlet temperature can increase dioxin emissions.

See

63 FR 14196, March 24, 1998. Based on a comment indicating that there can be an increase in short-term temperature fluctuations during startup (and shutdown), EPA is indicating in the startup standard that temperature measurements can increase by 10 percent during these periods.

Shutdown is the period of time between when kiln raw material feed is shutoff and gas flow through the kiln ceases. Shutdown operations are in many ways a mirror image of startup. During shutdown, the same transient conditions and low product production rates occur as during startup. Cement kilns cannot be immediately shut off. Even after the feed is stopped, gas flow must be continued through the kiln and the kiln continues to rotate to prevent kiln overheating and/or warping. Moreover, the concerns about inability to have normalized standards or standards with oxygen correction factors, air pollution control inlet temperature variability, and lack of measureable HCl emissions when the kiln is fired with distillate or natural gas and is not HCl CEM-equipped, all apply at shutdown for the same reasons as at startup. For this reason, we are setting the same limits for kilns during shutdown operations as during startup.

Periods of startup, normal operations, and shutdown are all predictable and routine aspects of a source's operations. In the proposed rule, EPA expressed the view that there are different modes of operation for any stationary source, and that these modes generally include startup, normal operations, shutdown, and malfunctions. 74 FR at 21162. However, after considering the issue of malfunctions more carefully, EPA believes that malfunctions are distinguishable from startup, shutdown and normal operations. Malfunction is defined as a “sudden, infrequent, and not reasonably preventable failure of air pollution control and monitoring equipment, process equipment or a process to operate in a normal or usual manner * * *” (40 CFR 63.2). EPA has determined that malfunctions should not be viewed as a distinct operating mode or condition and, therefore, any emissions that occur at such times do not need to be factored into development of CAA section 112(d) standards, which, once promulgated, apply at all times. In

Mossville Environmental Action Now

EPA,

370 F.3d 1232, 1242 (DC Cir. 2004), the court upheld as reasonable standards that had factored in variability of emissions under all operating conditions. However, nothing in section 112(d) or in caselaw requires that EPA anticipate and account for the innumerable types of potential malfunction events in setting emission standards.

See, Weyerhaeuser

Costle,

590 F.2d 1011, 1058 (DC Cir. 1978) (”In the nature of things, no general limit, individual permit, or even any upset provision can anticipate all upset situations. After a certain point, the transgression of regulatory limits caused by ‘uncontrollable acts of third parties,’ such as strikes, sabotage, operator intoxication or insanity, and a variety of other eventualities, must be a matter for the administrative exercise of case-by-case enforcement discretion, not for specification in advance by regulation.”)

Further, it is reasonable to interpret section 112(d) as not requiring EPA to account for malfunctions in setting emissions standards. For example, we note that Section 112 uses the concept of “best performing” sources in defining MACT, the level of stringency that major source standards must meet. Applying the concept of “best

performing” to a source that is malfunctioning presents significant difficulties. The goal of best performing sources is to operate in such a way as to avoid malfunctions of their units.

Moreover, even if malfunctions were considered a distinct operating mode, we believe it would be impracticable to take malfunctions into account in setting CAA section 112(d) standards for this (or any other) source category. As noted above, by definition, malfunctions are sudden and unexpected events and it would be difficult to set a standard that takes into account the myriad different types of malfunctions that can occur across all sources in the category. Moreover, malfunctions can vary in frequency, degree, and duration, further complicating standard setting.

In the event that a source fails to comply with the applicable CAA section 112(d) standards as a result of a malfunction event, EPA would, of course, determine an appropriate response based on, among other things, the good faith efforts of the source to minimize emissions during malfunction periods, including preventative and corrective actions, as well as root cause analyses to ascertain and rectify excess emissions. EPA would also consider whether the source's failure to comply with the CAA section 112(d) standard was, in fact, “sudden, infrequent, not reasonably preventable” and was not instead “caused in part by poor maintenance or careless operation.” 40 CFR 63.2 (definition of malfunction).

In response to comments urging that EPA not apply the same standards to malfunctions as to normal operation, EPA recognizes that even equipment that is properly designed and maintained can sometimes fail and that such failure can sometimes cause (or in the case of 30-day averages, contribute to) an exceedance of the relevant emission standard. (

See, e.g.,

State Implementation Plans: Policy Regarding Excessive Emissions During Malfunctions, Startup, and Shutdown (Sept. 20, 1999); Policy on Excess Emissions During Startup, Shutdown, Maintenance, and Malfunctions (Feb. 15, 1983)). EPA is therefore adding to the final rule an affirmative defense to civil penalties for exceedances of emission limits that are caused by malfunctions.

See

40 CFR 63.1341 (defining “affirmative defense” to mean, in the context of an enforcement proceeding, a response or defense put forward by a defendant, regarding which the defendant has the burden of proof, and the merits of which are independently and objectively evaluated in a judicial or administrative proceeding). We also added other regulatory provisions to specify the elements that are necessary to establish this affirmative defense; the source must prove by a preponderance of the evidence that it has met all of the elements set forth in 63.1344. (

See

40 CFR 22.24). The criteria ensure that the affirmative defense is available only where the event that causes an exceedance of the emission limit meets the narrow definition of malfunction in 40 CFR 63.2 (sudden, infrequent, not reasonable preventable and not caused by poor maintenance and or careless operation). The criteria also are designed to ensure that steps are taken to correct the malfunction, to minimize emissions in accordance with section 63.1348(d) and to prevent future malfunctions. In any judicial or administrative proceeding, the Administrator may challenge the assertion of the affirmative defense and, if the respondent has not met its burden of proving all of the requirements in the affirmative defense, appropriate penalties may be assessed in accordance with Section 113 of the Clean Air Act (

see also

40 CFR Part 22.77).

5. What are EPA's final actions on compliance dates?

For existing sources we proposed a compliance date of 3 years after the promulgation of the new emission limits for mercury, THC, PM, and HCl to take effect. This is the maximum period allowed by law.

See

section 112(i)(3)(A). We continue to believe a 3 year compliance period is justified because most facilities will have to install emissions control devices (and in some cases multiple devices) to comply with the proposed emissions limits. Therefore, we have retained a 3 year compliance data in this final rule.

For new sources, the compliance date w

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