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National Emission Standards for Hazardous Air 

Pollutants for Clay Ceramics Manufacturing

Background Information for Final Rule

Summary of Public Comments and Responses

September 2015
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National Emission Standards for Hazardous Air Pollutants

for Clay Ceramics Manufacturing

Background Information for Final Rule

Summary of Public Comments and Responses

Contract No. EP-D-11-084

Work Assignment No. 3-12

U.S. Environmental Protection Agency

Office of Air Quality Planning and Standards

Sector Policies and Programs Division

Research Triangle Park, North Carolina 27711

September 2015
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Disclaimer

This report has been reviewed by the Sector Policies and Programs Division of the Office of Air 

Quality Planning and Standards, EPA, and approved for publication. Mention of trade names or 

commercial products is not intended to constitute endorsement or recommendation for use.
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TABLE OF CONTENTS

List of Acronyms and Units of Measure........................................................................................ vi

1.0 Introduction............................................................................................................................... 1

2.0 Legal ......................................................................................................................................... 2

3.0 Applicability ............................................................................................................................. 6

3.1 Source Category.................................................................................................................... 6

3.2 Affected Sources................................................................................................................... 6

3.3 Exempt Sources .................................................................................................................... 7

4.0 Subcategories.......................................................................................................................... 10

5.0 Method 23 ............................................................................................................................... 11

5.1 General Opposition............................................................................................................. 11

5.2 Method 23 Not Revised ...................................................................................................... 12

5.3 Variations in Laboratory Execution.................................................................................... 14

5.4 Validation for Ball Clay Emission Sources........................................................................ 15

5.5 Sensitivity of Method 23..................................................................................................... 19

6.0 Format of Standards................................................................................................................ 20

6.1 Emission Limit Format/Units ............................................................................................. 20

6.2 Type of Standard................................................................................................................. 24

7.0 MACT Floors.......................................................................................................................... 28

7.1 Determining Sources in Floor Pool .................................................................................... 28

7.2 UPL..................................................................................................................................... 28

7.3 Emission Limit.................................................................................................................... 38

7.3.1 Manipulation of Data for MACT Floor ....................................................................... 41

7.3.2 3xRDL.......................................................................................................................... 47

8.0 Health-Based Standards.......................................................................................................... 50

8.1 Cumulative Effects ............................................................................................................. 50

8.2 General Support .................................................................................................................. 50

9.0 Work Practice Standards......................................................................................................... 51

10.0 Startup and Shutdown........................................................................................................... 56

11.0 Malfunction........................................................................................................................... 65

12.0 Testing and Initial Compliance Requirements...................................................................... 75

13.0 Continuous Compliance Requirements................................................................................. 82

14.0 Compliance Dates................................................................................................................. 94

15.0 Recordkeeping and Reporting............................................................................................... 95

16.0 Submission of Emission Test Results (ERT)........................................................................ 97

17.0 Definitions............................................................................................................................. 98

18.0 Costs and Impacts................................................................................................................. 99

19.0 Statutory and Executive Order reviews .............................................................................. 100

20.0 General Comments.............................................................................................................. 102

21.0 Other Comments................................................................................................................. 103
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List of Acronyms and Units of Measure

$ dollars

μg microgram

ρg picogram

ACI activated carbon injection

ANPR Advanced Notice of Proposed Rulemaking

ANSI American National Standards Institute

APCD air pollution control device

ASME American Society of Mechanical Engineers

Ass’n association

ASTM American Society for Testing and Materials

ATSDR Agency for Toxic Substances and Disease Registry

BDL below detection limit

BLD bag leak detection

BSCP brick and structural clay products

C Celsius

CAA Clean Air Act

CAM Compliance Assurance Monitoring

CBI confidential business information

CEDRI Compliance and Emissions Data Reporting Interface

CFR Code of Federal Regulations

Cir. Circuit Court

Cl2 chlorine

CMS continuous monitoring system

col. column

CPMS continuous parameter monitoring system

D.C. District of Columbia

D/F dioxins/furans

DLL detection level limited

dscm dry standard cubic meter

EDL estimated detection limit

EMPC estimated maximum possible concentration

EO Executive Order

EPA U.S. Environmental Protection Agency

ERT electronic reporting tool

F Fahrenheit

FCC Federal Communications Commission

FR Federal Register

FTIR Fourier transform infrared

GACT generally available control technology

HAP hazardous air pollutants

HCl hydrogen chloride

HCN hydrogen cyanide

HF hydrogen fluoride

Hg mercury
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HMIWI Hospital/Medical/Infectious Waste Incinerators

hr hour

HRGC high-resolution gas chromatography

HRMS high-resolution mass spectrometry

HxCDD hexachlorodibenzo-p-dioxin

i.e. id est (that is)

ICR Information Collection Request

id. idem (the same)

IQA Information Quality Act

ISO International Standards Organization

kg kilogram

L&E Locating and Estimating

lb pound

MACT maximum achievable control technology

MDL method detection level

Mg megagram

mg milligram

Mn manganese

NACAA National Association of Clean Air Agencies

NACWA National Association of Clean Water Agencies

Nat’l Hational

NESHAP national emission standards for hazardous air pollutants

ng nanogram

NRDC Natural Resources Defense Council

NSPS new source performance standard

NTTAA National Technology Transfer and Advancement Act

O2 oxygen

OCDF octachlorodibenzofuran

OM&M Operations, Maintenance and Monitoring

OMB Office of Management and Budget

PCDD Polychlorinated dibenzo-p-dioxins

PCDF Polychlorinated dibenzofurans

PM particulate matter

POC products of combustion

POM polycyclic organic matter

PRA Paperwork Reduction Act

QA quality assurance

QA/QC quality assurance/quality control

RDL reference detection limit

RDL representative detection level

RFA Regulatory Flexibility Act

SBAR Small Business Advocacy Review

SBREFA Small Business Regulatory Enforcement Fairness Act

SSM startup, shutdown and malfunction

TCDD tetrachlorodibenzo-p-dioxin

TCNA Tile Council of North America
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TEF Toxic Equivalency Factor

TEQ 2,3,7,8-TCDD toxic equivalents

tpy tons per year

U.S.C. United States Code

UPL upper prediction limit

v. versus

VE visible emissions

WHO World Health Organization
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1.0 Introduction

Section 112(d) of the Clean Air Act (CAA) requires the U.S. Environmental Protection Agency 

(EPA) to set emissions standards for hazardous air pollutants (HAP) emitted by major stationary 

sources based on the performance of the maximum achievable control technology (MACT). The 

EPA issued the national emission standards for hazardous air pollutants (NESHAP) for Clay 

Ceramics Manufacturing on May 16, 2003. The NESHAP was subsequently challenged, and the 

U.S. Court of Appeals for the D.C. Circuit vacated and remanded the standards on March 13, 

2007. To address the vacatur and remand of the original NESHAP, new standards were proposed 

and published in the Federal Register on December 18, 2014. The proposed standards regulate 

emissions of acid gases, hazardous metals, and dioxins/furans (D/F) from affected sources in the 

Clay Ceramics category.

An initial 60-day period ending February 17, 2015 was provided for the public to submit 

comments to the EPA on the proposal. The public comment period was subsequently extended to 

90 days, ending March 19, 2015. The following sections of this document summarize the public 

comments received on the proposal and present EPA’s responses to those comments. Public 

comments on the proposed Clay Ceramics NESHAP were received from seven commenters. See 

www.regulations.gov, Docket ID No. EPA-HQ-OAR-2013-0290 for the complete public 

comments on the Clay Ceramics NESHAP. Table 1 below lists the document numbers assigned 

to the public comments, the names of the commenters, and their titles and affiliations. For 

simplicity, only the last four digits of the document numbers specific to each commenter are 

presented in this document (e.g., 0247, instead of EPA-HQ-OAR-2013-0290-0247).

Table 1. List of Commenters on Proposed NESHAP for Clay Ceramics Manufacturing

Document Item No.

(EPA-HQ-OAR2013-0290-) Commenter/Title/Affiliation

0244 Michael J. Cassidy, EHS Specialist, Kohler Co.

0245 Anonymous

0246 Robert E. Hurt, Director, Environmental, Health & Safety, Dal-Tile Corp.

0247 Howard L. Gilberg, Counsel, Guida, Slavich & Flores, P.C., on behalf of Tile 

Council of North America (TCNA)

0248 Nicholas Morales, Earthjustice, on behalf of Natural Resources Defense 

Council & Sierra Club

0249 G. Vinson Hellwig, Michigan, and Robert H. Colby, Chattanooga, Tennessee, 

Co-Chairs, National Association of Clean Air Agencies (NACAA) 

0250 SSM Coalition et al. 
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2.0 Legal

In addition to the comments summarized and responded to below, public comments on legal 

issues can be found in section VI.A of the preamble to the Clay Ceramics final rule.

Comment 1: Commenter 0247 stated that past EPA actions recognize that the agency lacks the 

authority to list or develop a NESHAP where the subcategory has no major sources, and 

provided the following information supporting their statement:

• The EPA has recognized implicitly its lack of authority to list or develop a NESHAP for 

an industry that has no major sources. In the 2003 now-vacated major source NESHAP 

for this industry, for example, the EPA excluded the dinnerware and pottery 

manufacturing industries because neither subsector had a major source. In the preamble, 

the EPA first stated the statutory qualification criteria: “Today’s final rule for clay 

ceramics manufacturing applies to clay ceramics manufacturing facilities that are, are 

located at, or are part of, a major source of HAP emissions.” 68 FR 26715 (May 16, 

2003). The EPA then acknowledged the statutory exclusion criteria: “The clay ceramics 

industry also includes dinnerware and pottery manufacturing, but these industry segments 

are not covered by today’s final rule because we determined that there are no dinnerware 

or pottery manufacturing facilities that are major sources of HAP.” The EPA’s contractor 

explained: ”EPA defined the clay ceramics manufacturing source category to include 

facilities that produce pressed floor tile, pressed wall tile, other pressed tile and 

sanitaryware because no major sources were identified in the other segments of the clay 

ceramics manufacturing industry.”1

• The EPA recognized its constitutionally and statutorily imposed limitations at the 

proposal stage of the NESHAP rulemaking proposal process. For example, in its 2002 

proposed major source NESHAP for this subcategory, the EPA announced its decision to 

not propose major source NESHAP regulations for the clay minerals processing industry 

and the lightweight aggregate manufacturing industry because the EPA had determined 

that there were no manufacturing facilities in those industries that met the definition of a 

major source. 67 FR 47896 (proposed July 22, 2002).

• The EPA has declined at least eleven times to promulgate major source NESHAP for 

originally listed CAA Section 112(b) categories based solely on a determination that no 

major sources existed in them. See Chromium Chemicals Manufacturing (61 FR 28197 

(June 4, 1996)); Lead Acid Battery Manufacturing (id.); Non-Stainless Steel 

Manufacturing-Electric Arc Furnace (EAF) Operation; Stainless Steel ManufacturingEAF Operation (id.); Wood Treatment (id.); Aerosol Can-Filling Facilities (64 FR 63025 

(Nov. 18, 1999)); Antimony Oxides Manufacturing (id.); Alumina Processing (66 FR 

8220-01 (Jan. 30, 2001)); Dry Cleaning (Petroleum Solvent) (id.); Asphalt Concrete 

Manufacturing (67 FR 6521 (Feb. 12, 2002)); Uranium Hexafluoride Production (id.); 

Sewage Sludge Incineration (id.).

Response 1: This comment incorrectly merges two aspects of section 112 and thus fails to 

support the commenters’ position. As discussed in more detail in the preamble, the EPA lists

 1 Economic Analysis of the Clay Ceramics Manufacturing NESHAP: Final Rule, EPA-452/R-03-007, at page 1-4, 

EPA Office of Air Quality Planning and Standards (Feb. 2003).
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categories and source categories of major sources under section 112(c)(1), and then sets 

standards for them under other provisions in section 112. It is at the point of listing that the EPA 

determines that a category or subcategory contains major sources. All of the examples listed by 

the commenter cite to discussions of whether a category or subcategory should be on the section 

112(c) list; none are examples of what the commenter is advocating here: that EPA not set 

standards for a subcategory that is listed. The first two examples given by the commenter cite 

discussions of EPA’s decision not to include certain groups of sources (dinnerware and pottery 

manufacturing, clay minerals processing and lightweight aggregate manufacturing) as part of the 

clay ceramics category because those groups of sources did not include any major sources. The 

third set of eleven examples are all examples of where EPA delisted a group of sources after 

EPA determined that that they contained no major sources.

Comment 2: Commenter 0247 noted that CAA section 112(c)(1) instructed the EPA at the 

outset of the 1990s NESHAP program to develop a list of categories and subcategories in which 

a major source was operating. The EPA’s yardstick for the designation of categories and 

subcategories was whether: “there is reasonable certainty that at least one stationary source in the 

category is a major source or where sources in the category are commonly located on the 

premises of major sources.” Note that the EPA’s yardstick is temporal: it required the existence 

of a major source in the category before a major source standard could be lawfully developed. 

Here there is certainty that no major source exists. The basis for deciding whether to list a 

category is not whether there would be a major source in the category at an indeterminate time in 

the future.

Response 2: As discussed above and in more detail in the preamble, EPA lists categories and 

subcategories of major sources under section 112(c) based the information that it has at the time 

of the listing. Subsequently, EPA sets standards for each category and subcategory based on the 

listing under section 112(c). Deletions from the 112(c) list must be done consistent with the 

provisions of section 112(c)(9). New Jersey v. EPA, 517 F.3d 574, 581-583 (D.C. Cir. 2008). If a 

person believes that a category or source category should be deleted from the list, it may petition 

EPA for such deletion consistent with the provisions of section 112(c)(9)(B).

Comment 3: Commenter 0247 stated that the CAA NESHAP program does not authorize the 

EPA to regulate HAP emissions originating in mined minerals. All HAP proposed to be 

regulated in this NESHAP originate in, and are mined from the earth’s crust to provide raw 

materials for the production of ceramic tile. The EPA must heed Congress’ unambiguous 

instructions in the Joint Explanatory Statement contained in the Conference Report to the 1990 

CAA Amendments: “For categories and subcategories of sources of hazardous air pollutants 

engaged in mining, extraction, beneficiation, and processing of nonferrous ores, concentrates, 

minerals, metals, and related in-process materials, the Administrator shall not consider the 

substitution of, or other changes in, metal- or mineral-bearing raw materials that are used as 

feedstocks or materials inputs, or metal- or mineral-bearing materials processed or derived from 

such feedstocks or materials in setting emission standards, work practice standards, operating 

standards or other prohibitions or requirements or limitations under this section for such 

categories and subcategories. The prohibition in the preceding sentence shall not apply to the 

substitution, modification, or changes of chemicals (not including metal- or mineral-bearing 

materials) used in mining, extraction, beneficiation, or processing of nonferrous ores, 

concentrates, minerals, metals, and related in-process materials which is necessary to reduce air 
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emissions of such chemicals and for which substitutes that are safe and effective in performing 

the intended function of the chemical to be substituted are reasonably available.” H.R. Rep. No. 

101-952 (1990), at 339. While this is legislative history and not statutory language, it is 

noteworthy that it comes from the Conference Report, which is the best form of legislative 

history. The commenter stated that the EPA exceeded its statutory authority by proposing and 

finalizing a NESHAP for mined mineral-based emissions.

Response 3: The EPA disagrees that this text from the legislative history supports the

commenters’ argument that the EPA does not have the authority to set standards for the tile 

subcategories. First, as the commenter notes, this is legislative history and not statutory 

language. Indeed, the “Joint Explanatory Statement” cited by the commenter carries less weight 

than the Conference Committee Report, Sierra Club v. EPA, 353 F.3d 976, 988 (D.C. Cir. 2004), 

and so is not even the most authoritative legislative history. This statement cannot be read to 

negate either EPA’s broader authority to set standards based on the MACT floor under section 

112(d) or the specific statutory language in section 112(d)(2)(A) that expressly provides that 

EPA consider substitution of materials as a measure to reduce or eliminate emissions. See Sierra 

Club v. EPA, 479 F.3d 875, 882-82 (D.C. Cir. 2007) (in calculating MACT floors for brick and 

ceramics kilns, EPA cannot ignore non-technology measures such as the substitution of clay if 

those non-technology measures affect emissions levels). 

Second, the quoted text itself refers to sources “engaged in mining, extraction, beneficiation, and 

processing” of minerals, and does not extend to sources who use the minerals as raw materials to 

make a final product, such as ceramic tile. The tile manufacturers covered by the tile subcategory 

standards are not “engaged in mining, extraction, beneficiation, and processing” of minerals. 

Third, even if this statement superseded the statutory text and case law (which it does not) and if 

the tile manufacturers covered by this rule would fall within the scope of this text (which they do 

not), the consideration of the substitution of materials that this text addresses arises in the context 

of a beyond-the-floor analysis under section 112(b)(2), which is not what EPA is engaged in 

here. In this rule, EPA is setting standards based on the MACT floor, and is not considering any 

substitution of materials in setting the standards as part of a beyond-the -floor analysis under 

CAA 112(d)(2)(A) or otherwise.

Comment 4: Commenter 0247 stated that the EPA’s request for comment on whether to finalize 

the proposed NESHAP for ceramic tile manufacturing demonstrated the EPA’s self-doubt that it 

has the authority to finalize standards for the ceramic tile industry.

Response 4: The EPA disagrees that a request for comment on a matter demonstrates anything 

concerning the EPA’s confidence in the matter on which comment is taken. Section 307(d) of the 

CAA requires the EPA to publish a proposed rulemaking and provide an opportunity for public 

comment on that proposal, including comment on the underlying data, methodologies, legal 

interpretations, and policy considerations. Interested parties had an opportunity to comment on 

all aspects of this proposed rule, including on whether the EPA has authority to finalize the 

actions proposed. Whether EPA explicitly requested comment on a particular aspect of the 

proposal has no bearing whatsoever on legal arguments regarding the scope of the EPA’s 

authority and in no way suggests “self-doubt” regarding the scope of that authority.
5

Comment 5: Two commenters (0246 and 0247) argued that the CAA does not require NESHAP 

regulation of purported 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) emissions from the ceramic 

tile subcategory because the requirements of CAA section 112(c)(6) have already been met. The 

commenters noted that CAA section 112(c)(6) requires the EPA to NESHAP-regulate TCDD 

until “not less than 90 per centum of the aggregate emissions of [this] pollutant” has been 

NESHAP-regulated. The EPA announced in the Executive Summary to its Dioxin Reassessment 

Report, issued February 17, 2012, that the requirements of CAA section 112(c)(6) had been met. 

This provision, once met, preempts the EPA’s CAA section 112(d)(3) authority to regulate 

purported D/F emissions from this subcategory. The proposed D/F standard contravenes CAA 

section 112(c)(6) and must be withdrawn. 

Response 5: Under CAA section 112(c)(6), the EPA is required to list and then regulate 

categories and subcategories that account for “not less than 90 per centum” of the emissions of 

seven enumerated hazardous air pollutants. The plain language of this provision sets a minimum 

of 90 percent and does not, as commenters argued, provide that regulations are preempted if they 

would result in the regulation of more than 90 percent of these HAP. In short, while the EPA is 

required to get to 90 percent, it is not precluded from further regulation of these HAP after it 

reaches 90 percent.

Comment 6: Commenter 0248 stated that the EPA’s failure to set a standard for hydrogen 

cyanide (HCN) for Brick and Clay Ceramics violates CAA section 112. The commenter noted 

that the CAA mandates that EPA “shall require the maximum degree of reduction in emissions 

of the hazardous air pollutants subject to [section 112].” Therefore, the EPA is required to limit 

all hazardous air pollutants emitted from the source categories. CAA section 112(d)(2)-(3); Nat’l 

Lime Ass’n v. EPA, 233 F.3d 625 (D.C. Cir. 2000). It is unlawful for EPA to not set a limit for a 

section 112-listed pollutant. Nat’l Lime Ass’n, 233 F.3d at 634.

The commenter noted that HCN is listed as a hazardous air pollutant. HCN exposure at high 

levels swiftly harms the brain and heart, beginning with rapid breathing, followed by 

convulsions, and loss of consciousness, and can even cause coma and death. More commonly, 

even low-level exposure to HCN is associated with breathing difficulties, chest pain, vomiting, 

headaches, and enlargement of the thyroid gland (see Agency for Toxic Substances and Disease 

Registry (ATSDR), ToxFaqs for Cyanide (July 2006)). 

The commenter noted that electric generating units burning coal emit HCN and stated that it is 

also likely, then, that brick and clay ceramics units burning coal emit HCN. The EPA requested 

that brick and clay ceramics facilities test for hydrogen chloride (HCl), hydrogen fluoride (HF), 

and chlorine (Cl2) emissions but did not request they test for HCN emissions. The commenter 

stated, the EPA’s failure to require testing cannot excuse the EPA from its legal obligation to

regulate all emitted hazardous air pollutants. The commenter asserted that to fulfill its duty under 

the CAA, the EPA must set CAA section 112(d) standards for HCN.

Response 6: The EPA disagrees with the commenter that HCN standards must be set for coalfired clay ceramics kilns. In the clay ceramics manufacturing inventory, there are no kilns using 

coal as a fuel. All kilns use natural gas. Consequently, we were correct in not requiring the clay 

ceramics facilities test for HCN in the 2010 survey, and there is no reason to require clay 

ceramics facilities to test for HCN in the future.
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3.0 Applicability

3.1 Source Category

Comment 1: Commenter 0244 noted that their company is the only one in the United States 

affected by the proposed rule for clay ceramics.2 The commenter’s company operates three 

sanitaryware operations that emit area source quantities of HAP. Their company’s three facilities 

are co-located with major HAP sources that are separate and distinct from the sanitaryware 

manufacturing operations. If these three facilities were not so co-located, they would be area 

sources and not subject to the proposed rule. The commenter stated it is important for context to 

understand that this rulemaking applies a major source rule to three facilities that emit only area 

source quantities of HAP and so do not have major source impacts on health or the environment.

Response 1: The EPA appreciates the background context from the commenter on major source 

applicability for the sanitaryware manufacturing sector.

3.2 Affected Sources

Comment 1: Commenter 0244 recommended the applicability of first-fire glaze spray 

operations in 40 CFR 63.8540(c)(3) be clarified to state that this is for first-fire glaze application 

only, and that refire glaze spray operations are not subject to this subpart. This clarification is 

consistent with EPA’s intent per the November 6, 2014 memo from RTI International to EPA 

(Telander) titled “MACT Floor Analysis for Clay Ceramics,” which clearly identifies first-fire 

glaze operations in Section III.

The commenter also recommended the EPA specify how the first-fire glaze 0.1 percent metal 

HAP (dry basis) threshold is determined. The commenter asked whether it was EPA’s intent to 

evaluate percent HAP by glaze color, or by each spray booth, or across the entire facility. The 

commenter further asked whether the percent HAP will be based on usage for an entire year. For 

instance, most glazes that the commenter sprays are less than 0.1 percent metal HAP. If, due to 

equipment breakdown or other reason, a booth that normally only sprays glazes less than 0.1 

percent HAP needs to spray a first-fire glaze color that is greater than 0.1 percent HAP for one or 

two work shifts over the course of a year, the commenter asked whether that booth would then be 

subject to the MACT rule and the emissions limitations. The commenter stated that clarification 

is needed for sanitaryware facilities to be able to consistently determine MACT applicability for

first-fire glaze application stations. The commenter requested the applicability be determined for 

each first-fire spray booth as expressed in the November 6, 2014 memorandum from RTI 

International to EPA and that this intent be explained in this part of the rule. HAP content should 

be averaged for the amount of glaze sprayed over an entire calendar year per spray booth.

Response 1: The EPA agrees with the commenter’s request and has revised the applicability 

criteria as suggested for the final rule.

 2 See preamble sections VI.J.d and VII.A and B; Memo from RTI International to EPA (Telander), “Development of 

Cost and Emission Reduction Impacts for the Clay Ceramics NESHAP,” November 6, 2014; Memo from 

RTI International to EPA (Telander), “Updated Inventory Database and Documentation for Clay Ceramics Proposed 

Rule,” November 6, 2014; and Memo from RTI International to EPA (Telander), “Test Data Used in Clay Ceramics 

Proposed Rule,” November 6, 2014.
7

3.3 Exempt Sources

Comment 1: Commenters 0246 and 0247 argued that, since the EPA docket contains no D/F or 

other HAP emissions information for any ceramic tile production process that does not use ball 

clay as its primary raw material, EPA should add an exemption to the final NESHAP stating that 

any ceramic tile manufacturing process that does not use ball clay as its primary raw material is 

not subject to any aspect of the NESHAP, including any D/F standard. None are an “affected 

facility” for these purposes. Commenter 0247 noted that EPA assumes that the production of 

pressed ceramic tile requires the use of ball clay as the primary raw material. EPA’s assumption 

may or may not be correct today and may not be correct in the future. Without emissions 

information on these other possible operations, EPA’s proposal to regulate D/F emissions from 

all major sources that produce pressed tile is overly broad, and thus arbitrary and capricious.

Response 1: The EPA disagrees with the commenters’ suggestion that we revise the rule to 

exempt ceramic tile processes that do not use ball clay as the primary raw material from “any 

aspect of the NESHAP.” This option is not a viable one because ceramic tile kilns are still 

subject to acid gas, mercury (Hg), and particulate matter (PM) surrogate limits. Even if EPA 

were to exempt these sources from D/F emission limits, that would not exempt them from the 

limits for other pollutants or from any applicable work practice standards. An exemption from 

D/F emission limits based on primary raw material would also be problematic because a testing 

program conducted under the 2010 section 114 survey detected D/F in most test runs at all of the 

ceramic tile facilities tested. Therefore, there is no justification for an exemption, or even a work 

practice standard. The commenters’ exemption request is denied. 

Comment 2: Commenters 0246 and 0247 supported the proposed exemption of glaze lines that 

include glaze spray operations that use wet glazes containing less than 0.1 (weight) percent metal 

HAP (dry basis) from the definition of affected source. 40 CFR 63.8540(c)(3). Glaze lines with 

glaze spray operations are correctly expected by EPA to be an “insignificant source” of HAP 

emissions at major sources (79 FR 75656 (col. 1) (Dec. 18, 2014)).

Commenters 0246 and 0247 noted that EPA reached this same conclusion in the generally 

available control technology (GACT) standards for area sources in the ceramic tile 

manufacturing subcategory.3 The commenters asked that EPA follow its three-tiered area source 

GACT in this major source context, in addition to the exemption for specified wet 

glazes proposed in 40 CFR 63.8540(c)(3) (Dec. 18, 2014). The commenters asked that EPA to:

(1) exempt glaze lines with glaze spray operations that process less than 50 tons per year (tpy) of 

wet clay (40 CFR 63.11435(a) (2014)); (2) regulate PM surrogate emissions from glaze lines 

with glaze spraying operations that process more than 50 but less than 250 tons of wet clay 

according to the amount of non-exempt wet glazes they process using the same workplace 

standards as their area-source numeric counterparts (40 CFR 63.11438(c) (2014)); and (3) 

regulate glaze lines with glaze spray operations that process 250 tpy or more of non-exempt wet 

glaze in the final major source NESHAP emission limits.

Commenter 0247 requested clarification of one element of the proposed wet glaze exemption. 

The EPA docket contains the following exchange between Kohler, a proposed member of the 

 3 National Emission Standards for Hazardous Air Pollutants for Clay Ceramics Manufacturing Area Sources, 40 

CFR Part 63, Subpart RRRRRR (2014)
8

NESHAP sanitaryware subcategory, and EPA dated December 11, 2014 regarding the scope of 

this proposed exemption: [Kohler:] “Spray booth emission limits: Proposed limits apply to spray 

booths using only if glaze containing >0.1% metal HAP. Is this an average of glaze used in a 

booth or does it apply to any color? For instance, most of their glazes are <0.1% HAP. If due to 

equipment breakdown or other reason a facility needs to spray some glaze color that contains 

>0.1% in a booth for 1 work shift, say once per year, does this make this booth subject to the 

MACT rule and the emission limitation?” [EPA Response:] “The 0.1% metal HAP is an average 

of glaze used in a booth, and would include all colors used in that booth. The average would be 

on an annual basis, consistent with the information requested in the section 114 survey. We will 

clarify this in the final rule. Since it would be an annual basis, spraying a glaze color with >0.1% 

metal HAP for just 1 work shift would not be enough on an annual basis to make this booth 

subject to the MACT rule and emission limitation.” Commenter 0247 concurred with EPA’s 

response to Kohler and requested EPA likewise confirm this statement in the final NESHAP for 

the ceramic tile manufacturing subcategory and clarity the applicability criteria in the relevant 

portion of the preamble to the final rule.

Response 2: The EPA appreciates the commenters’ support for the exemption of glaze spray 

operations that use wet glazes containing less than 0.1 (weight) percent metal HAP (dry basis). 

However, the EPA disagrees with the commenters’ request that we implement the GACT 

provisions from the Clay Ceramics area source NESHAP. First, the area source NESHAP is 

authorized under CAA section 112(d)(5), and its provisions are not applicable to the major 

sources in this rule regulated under CAA section 112(d)(3). Second, the commenters have

misinterpreted the provisions in question. The first provision, cited as 40 CFR 63.11435(a),

exempted clay ceramics manufacturing facilities, not glaze lines, as the commenters reported. 

Regarding the second provision, the commenters appear to have mistakenly combined two 

different thresholds--50 tpy of wet clay in 40 CFR 63.11435(a) and 250 tpy of wet glaze(s) from 

40 CFR 63.11438(c) to create a new threshold of 50-250 tpy of wet clay.

The EPA agrees with Commenter 0247’s interpretation of our response concerning the wet glaze 

exemption. We have revised the regulatory text in the final rule to clarify the exemption. 

Comment 3: Commenter 0244 requested clarification of refire kiln applicability in 40 CFR 

63.8540(c)(1). While the commenter almost exclusively uses shuttle kilns to refire ware, some 

shuttle kilns may be permitted for first-fire ware as an operational contingency in the event of a 

first-fire tunnel kiln malfunction. Though permitted as such, these refire kilns have likely never 

processed a first-fire batch of ware. The commenter asked EPA whether the fact that a shuttle 

kiln is permitted for first-fire ware makes it subject to the rule, even though it likely has never 

processed first-fire ware. Similarly, if a circumstance arises in which a shuttle kiln does fire a 

batch of first-fire ware, the commenter asked whether it is now subject to the clay ceramics 

MACT rule. The commenter asserted that firing a single batch of first-fire ware every few years 

should not subject that kiln to the rule, and suggested that a “frequency of use” delineator or 

threshold should be included in this section for determining rule applicability. The commenter 

proposed that any refire shuttle kiln firing 4 batches/year or less of first-fire ware be excluded 

from rule applicability. Firing the equivalent of one batch of first-fire ware per calendar quarter, 

as an average, is an inconsequentially small quantity of emissions that should not trigger MACT 

applicability. Records of first-fire ware processing will be kept for applicability determination

purposes.
9

Response 3: The EPA cannot grant the requested exemption for refire shuttle kilns firing four 

batches/year or less of first-fire ware. The commenter has not provided the necessary data to 

substantiate their claim that firing four batches of first-fire ware would result in an 

inconsequentially small quantity of emissions.

Comment 4: Commenters 0246 and 0247 supported the following exclusions from the definition 

of “affected facility” proposed in 40 CFR 63.8540(c)(1)-(5) (79 FR 75694 (col. 1)(Dec. 18, 

2014): (1) Kilns that are used exclusively for refiring; (2) kilns that are used exclusively for 

setting glazes on previously fired products; (3) glaze spray operations that use wet glazes 

containing less than 0.1 (weight) percent metal HAP (dry basis); (4) raw material processing and 

handling; and (5) wall tile press dryers.

Response 4: The EPA appreciates the commenters’ support for the applicability criteria in the 

proposed rule and directs the commenters’ attention to additional clarifications to the criteria that 

have been made for the final rule in response to other public comments.
10

4.0 Subcategories

Comment 1: Commenters 0246 and 0247 supported the subcategorization of ceramic floor tile 

manufacturing, ceramic wall tile manufacturing, and sanitaryware manufacturing.

Response 1: The EPA appreciates the commenters’ support. As noted in the proposal preamble, 

“based on our review of the available information on the clay ceramics manufacturing industry, 

we determined that there are three distinct sectors within the industry: (1) Ceramic floor tile; 

(2) ceramic wall tile; and (3) sanitaryware. Specifically, the EPA found that the ceramic floor 

tile, ceramic wall tile and sanitaryware sectors of the industry differ in terms of raw materials, 

processes and final products.” (79 FR 75655) It should be noted that the determination of these 

industry sectors is distinct from our subcategorization of the industry sectors, which includes two 

subcategories for sanitaryware kilns--(1) sanitaryware periodic (shuttle) kilns and 

(2) sanitaryware continuous (tunnel) kilns; and three subcategories for sanitaryware glazing--

(1) manual glaze spraying, (2) spray machine (or chain-on-edge) glaze application, and (3) robot 

glaze spraying.
11

5.0 Method 23

5.1 General Opposition

Comment 1: Commenters 0246 and 0247 opposed the proposed D/F standard. The commenters

argued that EPA’s proposed D/F standard is arbitrary and capricious because it is not supported 

by scientifically and legally valid D/F emissions data. The commenters also noted that mass 

emissions of 2,3,7,8-TCDD toxic equivalents (TEQ) from all ceramic tile manufacturing sources 

in the EPA docket are less than 3.5 grams per year and remarked that this is a miniscule amount 

dispersed over a huge area. The commenters strongly questioned the validity of the emissions 

data and EPA’s right to regulate D/F emissions without a validated stack testing method. The 

commenters asserted that no judicial precedent supports regulating theoretical D/F emissions 

from this subcategory and challenged the EPA’s legal authority to continue with regulating D/F 

emissions from this sector.

Commenter 0247 noted that EPA’s basis for the proposed D/F standard is CAA Section 

112(d)(3)(B), which requires emissions standards to be based on: “the average emission 

limitation achieved by the best performing 5 sources (for which the Administrator has or could 

reasonably obtain emissions information) in the category or subcategory ...” . The commenter 

stated that to set quantitative emission standards, emissions information must be scientifically 

valid, quantitative data. The commenter objected to the D/F standard for the ceramic tile 

manufacturing subcategory because they claim Method 23 is incapable of producing accurate

data for a MACT standard. Without this foundation, the commenter asserted, the proposed D/F

standard must be withdrawn as arbitrary and capricious. 

The commenter noted that the ceramic tile manufacturing industry conducted stack testing to 

measure D/F emissions using Method 23 in response to a March 2010 EPA Information 

Collection Request (ICR). The results of that stack testing provide the only quantitative D/F

information in the docket supporting the proposed D/F standard. However, the commenter 

argued the Method 23 has never been validated for the ball clay matrix found in the ceramic tile 

manufacturing industry, and cannot be followed, as it is written. The companies that received the 

ICR went to great expense to comply and engaged a well-respected companies with stack testing 

and laboratory experience with specific Method 23. However, the commenter asserted that 

Method 23 does not generate scientifically valid data usable for the development of a MACT 

standard. Method 23 was designed and validated at a time when biogenic D/F encapsulated in a 

solid ball clay matrix was not known. The EPA’s Method 23 validation focused on 

anthropogenic D/F in a gaseous media as the only known D/F source at the time of the method 

was development.

The commenter noted that biogenic dioxin encapsulated in ball clay was discovered in 

Mississippi in 1996. Many types of ball clay do not contain D/F, but when it is present, it is 

encapsulated within highly charged clay platelets in a ball clay matrix. The commenter argued 

that these strong bonds severely limit the environmental availability of dioxin. They further 

noted that Method 23 was developed almost two decades before this 1996 discovery and the 

method was based on the analytical requirements from the 30-year old EPA Method 8290. Its 

clean-up procedures date back to 1974. The commenters asserted that Method 23 cannot be 

validated as currently written for ball clay because it cannot distinguish between free dioxin and 
12

dioxin that is bound and encapsulated as a particulate in the ball clay matrix and therefore, not 

environmentally available.

Response 1: The EPA disagrees with the general comment that the proposed MACT dioxin and 

furan standard is without factual support. We have provided specific responses to individual 

comments on the validity of stack testing methodology and data used to measure dioxin and 

furan concentration in stationary source stack emissions later in this section. We proposed limits 

to emissions for these classes of hazardous air pollutants based on empirical data collected from 

potential emission source(s) for these compound classes in this source category. We take 

exception and disagree with the statement that 3.5 grams per year of chlorinated 

dibenzo(p)dioxin and chlorinated dibenzofuran emissions are insignificant since the regulatory 

mandate in the CAA of 1990 (CAA) for Title III hazardous air pollutants are based on the 

demonstrated ability to control the target pollutant and EPA is obligated under the CAA to set 

limits based on data demonstrating the performance of sources in specific source categories. Our 

mandate to regulate in the CAA is not based on absolute mass of the emissions but rather on

1. the ability to control those emissions,

2. the emissions originate predominantly from a small number of sources and 

3. the environmental effects of the chlorinated dioxin and furan classes of compounds are 

significant at low concentration. 

While we do not dispute that there may be differences in the implementation of Method 23 

among specialty laboratories performing analysis for dioxins and furans, EPA asserts that the 

quality control inherent in the method provides adequate support for the validity and accuracy of 

the emission results. 

We also disagree with comments about the validity of the test method used to determine 

chlorinated dioxin and furan emissions from this source category. Such a general statement that 

the chlorinated dioxin and furan classes emitted as particulate bound or gaseous hazardous air 

pollutants from stationary sources in the category are different from other stationary source 

categories where Method 23 has been successfully implemented is without merit and the 

commenter provides no data to support this claim. The same method requirements regarding the 

recovery of isotopically labeled dioxin and furan congeners apply for evaluating the validity of 

data for this source as they would be from any other air emission source. Review of the data 

submitted by the industry through the ICR process provides adequate information to determine 

that the recovery of labeled dioxin and furan congeners met method requirements and that the 

analysis of said samples generated valid data on emission concentration.

5.2 Method 23 Not Revised 

Comment 1: Commenter 0247 argued that Method 23 has not been revised and is, therefore, not 

valid. The commenter noted that standards developed by the American Society for Testing and 

Materials (ASTM), American National Standards Institute (ANSI), and the International 

Standards Organization (ISO) are required to be periodically revised, reaffirmed, or withdrawn. 

Typically, the review process is required at least once every 5 years. The Information Quality 

Act, 44 U.S.C. 3501-3520, requires the EPA to review its methods. EPA’s stack testing methods 
13

experts are among those at EPA that hold memberships in these consensus standards-setting 

organizations, and actively support their approaches and work.

The commenter stated that the EPA, the private sector, and academia know Method 23 has 

problems. EPA had prioritized a broad rewriting of Method 23 in 2007, but to date EPA has 

failed to update the method. The commenter asserted that EPA has had ongoing knowledge and 

has worked to rectify issues with Method 23. The EPA first used Method 23 to measure D/F 

emissions from the ball clay matrix in mid-2003 and, according to the commenter, the EPA

realized at that time the unique challenges presented by the ball clay matrix. In 2009, the 

commenter stated the EPA initiated discussions with experts in the field of dioxin stack 

measurement, including Dr. Yves Tondeur, a principal author of Method 8290 and principal 

contributor to Method 23. Commenter 0247 stated that Dr. Tondeur developed and presented 

EPA with a major rewrite of Method 23, which was discussed at the public Source Evaluation 

Society conference in Arizona in 2011. A substantial EPA contingent met in Wilmington, North 

Carolina in 2013 with Dr. Tondeur and other members of the dioxin measurement community 

with the goal of moving forward with drafting a new dioxin measurement method (proposed 

EPA Method 8223) and revising the analytical portion of Method 23. Dr. Raymond Merrill, EPA 

Director of Methods Development delivered an internal presentation titled “What You Always 

Wanted to Know About EMPC But Were Afraid to Ask” at the internal EPA Measurement 

Technology Workshop in 2013. The commenter asserted that these facts establish that the EPA 

has been well aware of long-standing inaccuracies and problems with Method 23, and believes 

that since Method 23 was not revised, it is not valid.

According to the commenter, public presentations by EPA’s dioxin policy and Method 23 

experts also confirm that Method 23 is deeply flawed. The commenter also alleged that EPA 

staff acknowledge that no two analytical labs run Method 23 the same way or as required by the 

Method because of these flaws. The commenter stated the EPA has informally solicited those in 

private industry that it deems knowledgeable in this field, including its own certified contractors, 

seeking input and suggestions on how to rewrite Method 23. The commenter also stated that 

segments of the private stack testing industry and academics share these and other concerns. 

They also stated that the EPA is aware that the equipment, materials and processes specified for 

Method 23 have been replaced by more accurate technology, but note they have not been 

validated for Method 23 or for Method 23 used to measure D/F in ball clay. The commenter 

alleged that Method 23 requires outdated equipment, materials, and processes, including some 

equipment have not been available for many years. If Method 23 was an ANSI, ASTM or ISO 

standard, the commenter noted it would have been updated multiple times since its initial 

issuance or withdrawn. The commenter stated that EPA’s failure to update Method 23 for known 

problems “is alarming and egregious.”

The commenter stated that while Method 23 is EPA’s only and thus “best” D/F air quality 

measurement tool, it does not mean the D/F data submitted by the industry in response to EPA’s 

March 2010 ICR is scientifically valid or legally usable. The commenter understands the EPA 

plans to issue in late 2015 or 2016 an Advanced Notice of Proposed Rulemaking (ANPR) 

associated with a Method 23 rewrite that will include the ball clay matrix. The commenter stated 

the EPA first used Method 23 in an attempt to measure D/F emissions from the ball clay matrix 
14

in mid-2003, and argued the EPA has had over eleven years to revise Method 23 and has failed 

to do so. The commenter argued that this ANPR is a required first step.

The commenter noted the EPA has issued guidance on category- and subcategory-specific 

patches for Method 23 that acknowledge the flaws in Method 23,4 and have issued NESHAP 

reflecting stack testing results generated by a modified Method 23. EPA has failed to do so for 

the ceramic tile manufacturing subcategory, the commenter contends, because EPA knows the 

method has not been validated for the ball clay matrix in this subcategory and that patches 

presume the method has been validated and needs only “tweaks” to provide data usable for 

regulatory purposes. Patches and other guidance have no legal effect because they have not been 

subject to the same Administrative Procedures Act process, including notice and comment, to 

which current EPA test methods are subject. The commenter alleged that none of the other 

industry-related changes or anything else in Method 23 address and resolve the issues specific to 

the ball clay matrix found in the ceramic tile manufacturing industry.

The commenter further stated that CAA section 112 deadline for EPA to issue the proposed 

NESHAP does not provide EPA authority to use results from test methods that have not been 

validated to be “emissions information” as that term is used in CAA section 112(d)(3). The 

commenter asserted the EPA must withdraw its proposed D/F standard for this subcategory 

because it is not based on “emissions information.”

Response 1: The EPA disagrees with the fundamental tenant that a method is invalid on the 

grounds that it has not been revised or updated. When Method 23 is used to measure air 

emissions of chlorinated dioxins and furans from stationary source, the results from those tests 

are as valid today as they were when the method was first promulgated. It is true that 

improvements to all measurement method evolve over time as experience grows using the 

method. Furthermore, facilities certified that the data was accurate and complete for the ICR 

process. As EPA reviews data from various ICR campaigns, variations in laboratory procedure 

that were documented in test reports were shown to be improvements to the existing Method 23 

procedure making the data valid and useful for its purpose in the ICR.

5.3 Variations in Laboratory Execution 

Comment 1: Commenter 0247 argued that Method 23 data used to generate the MACT floor are 

not valid due to variations in laboratory execution. The commenter cited flaws in Method 23 in 

the following areas:

1. AX-21 Activated Carbon

2. Methylene Chloride and Toluene Residual Quality Control

3. Verification 

4. Benzene Usage

5. Chromic Acid Glass Soaking/Cleaning

6. Glass Cleaning Generally

7. Packed Columns

 4 See (ALT-034) Approved Modifications to Method 23 for Secondary Aluminum Facilities, (ALT-036) Approval 

of Method 23 Modifications for Cement Kilns, (ALT-052) Approved Method 23 Modifications for Incinerators and 

Waste Combustors, and (ALT-065) Approval of Methods 23 and 320 for 40 CFR part 63, subpart EEE.
15

8. Gravity Column Chromatography Efficiency

9. Ion Mass Interferences/Coelutants

a. Molecular Interferences

b. Ion Fragment Interferences

10. Precision and Bias

11. Comparison of Method 23 to Globally Recognized Standards for Scientific Reliability 

and Accuracy

Response 1: Method 23 is a self-validating method. The compounds that are on the list of 

required targets for this method have unique physical and chemical properties. Implementation 

of Method 23 by each test team is evaluated against the recovery of isotopically labeled 

standards. The sampling media, XAD-2®, is spiked before it is used to collect stack gas samples. 

Samples are also spiked with isotopically labeled standards when they are prepared in the 

analysis laboratory to evaluate the extraction and preparation of the samples for analysis. If the 

spike recoveries are within the method specifications and other method quality control was met 

for the method, the data are considered valid. While EPA agrees Method 23 could be improved 

with modifications, EPA’s ongoing effort to update Method 23 does not invalidate the data that 

was collected from stack tests in 2010.

5.4 Validation for Ball Clay Emission Sources

Comment 1: Commenter 0246 and 0247 argued that Method 23 has not been validated 

specifically for ball clay emission sources. Commenter 0247 alleged the EPA issued the March 

2010 ICR with prior knowledge of the limitations of Method 23. Given EPA’s documented 

knowledge that Method 23 had not been validated for the ball clay matrix, along with the 

numerous limitations of the method, specifying its use for the 2010 ICR was egregious, 

extremely costly, scientifically flawed, and arbitrary and capricious. The commenter alleged that 

some segment of EPA initiated this regulatory development process with a conclusion that D/F

emissions might, or do, arise from the ball clay matrix used in the ceramic tile manufacturing 

industry, and then other segments worked backward to find D/F results using Method 23 to 

validate that conclusion. The commenter stated that using a test method that “lacked validation to 

come to any conclusions in that context is unquestionably arbitrary and capricious” and argued 

the EPA is obligated to withdraw the proposed D/F standard. EPA should have developed and 

validated a D/F stack testing method for biogenic, encapsulated D/F in the ball clay matrix

before beginning this rulemaking. Only after it has a validated D/F method for the solid ball clay 

matrix that encapsulates D/F, if it is present, is EPA legally permitted to proceed with an ICR 

and develop a D/F standard for the ceramic tile manufacturing subcategory.

Commenter 0247 claimed Method 23 is flawed in at least 17 ways and argued that any one of 

these flaws are legally sufficient to draw the conclusion that the proposed D/F standard is 

arbitrary and capricious and must be withdrawn. The ceramic tile manufacturing industry should 

have been advised by EPA of the problems with Method 23 prior to the ICR testing. The ceramic 

tile manufacturing industry learned after completion of the ICR-mandated stack testing that 

several requirements of Method 23 are impossible to satisfy. These problems render the 

emissions data collected by industry unusable for this or any other regulatory purpose; they are 
16

scientifically invalid, their accuracy is uncertain, and their legal eligibility for use in the 

development of a proposed D/F Standard for this industry has been voided.5

Commenter 0247 noted a number of alleged failures in Method 23 applicable to the ceramic tile 

manufacturing industry and the ball clay matrix, including:

1. Method 23 Has Not Been Validated for Use in the Biogenic Ball Clay Matrix

2. EPA’s Validation of Method 23 for Municipal Waste Combustors Does Not Carry Over 

to Ceramic Tile Manufacturing Sources

3. Method 23 Sample Gathering and Laboratory Handling Requirements Further 

Compromise the Validity of the Emissions “Data” Used by EPA to Support its MACT 

D/F Emissions Limits

a. The Heated Method 23 Filter Alters the Solid Stack Gas Sample, So Method 23 

Emission Data Do Not Reflect Actual D/F Stack Emissions

b. Soxhlet Extraction is Accretive to the Unreliability of D/F Emissions Information

4. Moisture Removal Requirements

5. Absence of Recovery Methodology

6. Field Surrogates

Response 1: The EPA disagrees with the conclusion that the Method 23 is incapable of 

generating scientifically valid data. Method 23 has been validated in previous tests and will be 

validated every time a source test is conducted as long as the recoveries of the spiked sample 

media meet the recovery criteria in the method. Method 23 as originally written and in all of the 

variations documented in the ICR results requires labeled isotope spikes to determine the 

recovery of the target compound classes for this method. Isotopic label recovery as previously 

noted in this response to comment validates the sampling and chemical procedures to generate 

results within acceptable performance requirements. Our review of the ICR data showed that the 

recovery of isotopically labeled compounds used as quality checks of Method 23 performance 

for samples from ceramic tile exhaust were within acceptable limits for data submitted in 

response to the ICR. Subsequent procedures to normalize the analysis data for recovery of 

isotopically labeled standards used in sample extraction and preparation were performed and 

correctly used to generate valid laboratory data. Method 23 validation for clay ball matrix

occurred with the ICR test data and past method 23 test results that met the recovery standard 

requirements of the method. These recoveries are presented in the following table.

Dioxin/furans were present in tests conducted on the ceramic tile exhaust. Method 23 has been 

used and proven to give valid data for particle bound and gaseous chlorinated dioxins and furans 

in several source categories including Hospital/Medical/Infectious Waste Incinerators (HMIWI)

and Portland Cement MACT. While the method has room for improvement and the EPA is 

working on updating Method 23, the need for improvement does not invalidate the data that was 

collected from stack tests in 2010. Furthermore, the commenter provides no data to demonstrate 

their conclusion that Method 23 results as implemented by testing teams are less valid than the 

 5 This comment includes a non-exclusive list and associated discussion of Method 23 flaws, omissions and issues. 

Commenter 0247 highlighted the most material of these as applied to the ceramic tile manufacturing industry. The 

commenter stated that each flaw, omission and issue in and of itself is sufficient basis to reject the data used by EPA 

to develop a MACT D/F floor, and to reject the proposed D/F standard.
17

results generated by the method run as written. In fact, EPA asserts, testing teams that employed 

improvements including substitution for materials or supplies that were not available to them at 

the time of testing demonstrated results of equal or better validity, as demonstrated by isotopic 

labeled spike recovery, than the requirements in Method 23 as written. We provide Table 1 as an 

example from ICR results to demonstrate labeled spike recovery.

Commenters should note that modification requests to Method 23 during the ICRs have been 

granted to include the following:

Laboratory does not use silica gel in the soxhlet apparatus.

• All provided solvent rinses are combined, concentrated, and added to the resin/filter 

components before soxhlet extraction.

• Prior to cleanup, the extract is dried with sodium sulfate and Cleanup Recovery Standard 

is added.

• The extract is split for archival. Tetradecane is added to the remaining half and the extract 

is concentrated to the tetradecane.

• The extract undergoes Acid/Base Silica Gel column and Florisil column cleanup. Basic 

Alumina and AX-21 Carbon/Celite 545 Columns are not used.

• After cleanup, the eluate is concentrated, added to a conical vial containing tetradecane 

and Recovery Standard Solution, and concentrated again to a final volume of 20:l. 

• The internal standard mix includes 13C-OCDF. The concentration of the 13C-OCDF is 

200pg:l. OCDF is quantified against 13C-OCDF.

• The Initial Calibration curve includes six levels; the concentration of the lowest level is 

at one-half the low point of the curve in Table 2 of Method 23.

• Addition to Table 4 of Method 23 for CDD only:

o Number of Cl2 Atoms – 5

o Ion Type – M+2/M+4

o Theoretical Ratio – 0.65

o Lower Control Limit – 0.55

o Upper Control Limit – 0.75
18

Table 1 (generated from data in EPA-HQ-OAR-2013-0290-0069)

Field Spike Standards L924489-1* 

% Recovery

L924489-2 % 

Recovery 

L924489-3 % 

Recovery 

L924489-4 % 

Recovery 

37Cl4-2,3,7,8-TCDD 94 91 94 91

13C12 -1,2,3,4,7,8-HxCDD 97 121 82 104

13C12 -2,3,4,7,8-PeCDF 101 100 97 92

13C12 -1,2,3,4,7,8-HxCDF 96 94 73 98

13C12 -1,2,3,4,7,8,9-HpCDF 94 89 94 89

Field Spike Standards L924489-6

% Recovery

L924489-7 % 

Recovery

L924489-8 % 

Recovery 

L924489-9 % 

Recovery 

37Cl4-2,3,7,8-TCDD 93 92 89 93

13C12 -1,2,3,4,7,8-HxCDD 88 76 103 106

13C12 -2,3,4,7,8-PeCDF 91 95 101 106

13C12 -1,2,3,4,7,8-HxCDF 91 95 86 96

13C12 -1,2,3,4,7,8,9-HpCDF 102 112 98 107

Field Spike Standards L924489-10

% Recovery

L924489-11 

% Recovery 

L924489-12 

% Recovery 

L924489-13 % 

Recovery 

37Cl4-2,3,7,8-TCDD 77 87 88 89

13C12 -1,2,3,4,7,8-HxCDD 89 96 127 99

13C12 -2,3,4,7,8-PeCDF 67 75 71 104

13C12 -1,2,3,4,7,8-HxCDF 86 89 79 115

13C12 -1,2,3,4,7,8,9-HpCDF 93 88 88 98

Field Spike Standards L924489-14

% Recovery

L924489-15 

% Recovery 

L924489-16 

% Recovery 

L924489-17 % 

Recovery 

37Cl4-2,3,7,8-TCDD 89 91 105 105

13C12 -1,2,3,4,7,8-HxCDD 99 118 103 102

13C12 -2,3,4,7,8-PeCDF 104 99 118 115

13C12 -1,2,3,4,7,8-HxCDF 115 83 91 87

13C12 -1,2,3,4,7,8,9-HpCDF 98 103 103 107

Field Spike Standards L924489-18

% Recovery

L924489-19 

% Recovery 

37Cl4-2,3,7,8-TCDD 99 99

13C12 -1,2,3,4,7,8-HxCDD 90 103

13C12 -2,3,4,7,8-PeCDF 110 108

13C12 -1,2,3,4,7,8-HxCDF 86 89

13C12 -1,2,3,4,7,8,9-HpCDF 102 107

*Method Blank Train 1 was not spiked with field spike Standards
19

5.5 Sensitivity of Method 23

Comment 1: Commenter 0247 argued that Method 23 is not sensitive enough to measure the 

concentration of chlorinated dioxins and furans at the level of the standard. The EPA MACT 

floor calculations are at picogram (ρg) levels that require laboratory measurement quantification 

limits below calibration ranges for the high-resolution gas chromatography and high-resolution 

mass spectrometry (HRGC/HRMS) equipment specified by Method 23. Commenter 0247 was 

concerned because two of the proposed D/F emission standards are based on measurements 

below the reference detection limit (RDL). Scientists have devoted a great deal of attention to 

detection limits, and adherence to set quantification limits that have a strong statistical 

confidence in measured amounts of individual D/F analytes is necessary. The commenter was 

also troubled by the use of estimated maximum possible concentrations (EMPCs) and qualified 

emissions information measured at below detection limits and noted that Method 23 is 

completely silent on these important data quality issues.

Response 1: EPA disagrees with the commenter’s conclusion that the detection limit capabilities 

of their chosen test contractor were inadequate to justify the MACT floor calculations at 

picogram levels. Method 23 defines the detection limit as an estimated detection limit or “EDL”. 

The test contractor reported EDL in the range of 1.4 to 7.1 ρg. Quantitative limits based on these 

EDL could be estimated worst case of approximately 21 ρg for any target chlorinated dioxin or 

furan. (Compared to a Utility RDL laboratory community average of 77ρg by mass or 9 ρg by 

TEQ).

If there are errors associated with the extraction and recovery of the samples from the stack, EPA 

believes that the calculation of the floor by the upper predictive limit (UPL) takes into account 

these errors and general variability in the process of achieving detectable measurements. Thus to 

ensure the process and measurement variability is adequately addressed when there are 

undetectable measurements, we compare the upper prediction limit (UPL) against three times the 

representative detection level (3xRDL). If the floor is less than three times the RDL, we adjust 

the floor level to three times the RDL. The dioxin and furan data was above the detection limit, 

so adjusting to the RDL was not necessary. However, we account for measurement variability 

via the use of the UPL, which was used to set the floor, and not 3xRDL.
20

6.0 Format of Standards

6.1 Emission Limit Format/Units

One significant public comment on emission limit format can be found in section V.C.2 of the 

preamble to the Clay Ceramics Manufacturing final rule. The remaining public comments and 

the EPA’s responses are presented in this section.

Comment 1: Commenter 0247 challenged the Toxic Equivalency Factors (TEF) proposed in 

Table 5 [79 FR 75709 (Dec. 18, 2014)(proposed to be codified as Table 5 of 40 CFR 63, subpart 

KKKKK)] because those values do not follow EPA’s Recommended Toxicity Equivalence 

Factors (TEFs) for Human Health Risk Assessments of 2,3,7,8-Tetrachlorodibenzop-dioxin and 

Dioxin-Like Compounds. [Risk Assessment Forum, EPA/600/R-10/005, U.S. EPA (2010)] 

According to the commenter, the proposed Table 5 reflects World Health Organization (WHO)

2005 TEF values. The commenter stated that EPA offered no explanation or justification for 

ignoring its own values published in 2010 in its arbitrary selection of the WHO 2005 values.

Response 1: The EPA disagrees with the commenter that we did not use the recommended TEFs 

for dioxin/furan congeners in the Clay Ceramics proposed rule. We attempted to find the

EPA/600/R-10/005 document that the commenter references, but could only find the

EPA/100/R-10/005 version, which is in the docket for the Clay Ceramics Manufacturing rule.

The citation from the commenter (EPA/600/R-10/005) is provided at the bottom of the Abstract 

in the EPA document, which is different from the citation on the cover page of the EPA 

document (EPA/100/R-10/005). This may explain the discrepancy. Regardless, the EPA 

document in question recommended the use of the WHO 2005 TEF values (see Abstract). The 

TEF values listed in Table 2 of the EPA document are the same TEF values listed in Table 5 of 

the proposed rule.

Comment 2: Commenter 0244 contended that the sanitaryware kiln emission limits in Table 1 to 

the proposed rule should apply to each kiln’s POC (products of combustion) stack only. The 

commenter requested that this be stated in the table and elsewhere in the rule. Tunnel kilns are 

designed with a primary exhaust stack in the front part of the kiln and with 2 or 3 auxiliary stacks 

used for ware cooling in the back half of the kiln. The primary exhaust stack discharges the 

products from combustion of natural gas, plus the vitrifying zone atmosphere containing the 

HAP emitted from the ware (i.e. HF). The cooling stacks essentially exhaust ambient air used for 

ware cooling in the kiln. Air movement (draft) in a tunnel kiln combustion section is always 

maintained in the direction of the POC stack to maintain proper operating pressures in the preheat and vitrification zones. This means air moves from the end of the vitrification zone (middle 

of the kiln) toward the POC stack exhaust point. Proper draft maintains proper pressure in the 

kiln, which is key to proper kiln operation and minimizes scrap and fuel use. Tunnel kilns are 

designed and operated to restrict air flow from the vitrifying zone towards the cooling zone. 

Some tunnel kilns even have brick baffles on the downstream end of the vitrifying zone to inhibit 

air flow into the ware cooling section. This design accomplishes two goals: (1) it maximizes 

ware yield by eliminating multiple potential ware defects that are created by vitrifying zone 

atmosphere contacting vitrified ware; and (2) it minimizes heat loss and fuel use (operating 

costs).
21

According to the commenter, this issue was addressed with EPA during the ICR testing process 

when all cooling exhaust stacks on all kilns were screened for oxygen (O2) content. If the 

O2 content measured 20.4 percent or higher, the stack was considered to essentially exhaust 

ambient air and no ICR testing was required. The cooling exhaust stacks on all tunnel kilns, 

except Spartanburg SC tunnel kiln 10, had O2 concentrations greater than 20.4 percent and so 

were not tested under the ICR test program in accordance with a prior agreement with EPA. 

These results are included in the test reports submitted to EPA. The O2 concentration in the 

TK10 cooling exhaust stack measured between 20.0 and 20.4 percent. For reference, the 

commenter indicated this was the kiln in which EPA forced the restart of the shutdown wet 

scrubber for ICR testing. As this was not how this existing kiln operated, and the scrubber had 

been shut down for the prior 17 months and only restarted days before the ICR testing, the 

commenter indicated it was likely that use of the scrubber for the short time the emissions testing 

took place affected normal airflow through and pressures in the kiln, which may not have been 

properly stabilized for ICR testing and possibly forced vitrifying zone atmosphere into the 

cooling zone.

If EPA does not find the commenter’s request acceptable, the commenter stated that EPA must 

clarify specific stack applicability criteria, as testing for the regulated HAP is very expensive, 

and requiring the testing on stacks exhausting ambient air is a very unreasonable burden to place 

on any sanitaryware facility, especially when these tunnel kilns have already been shown to only 

emit HAP in area source quantities (see Table 8 in the November 6, 2014 memo from RTI 

International to EPA titled “Development of Cost and Emission Reduction Impacts for the Clay 

Ceramics NESHAP”).

Response 2: With one small exception, the EPA agrees with the commenter’s understanding of 

the issue and has revised the testing provisions for the final rule to clarify that stacks to be tested 

at sanitaryware manufacturing facilities are to be limited to POC stacks and those cooling stacks 

with an oxygen content at or below 20.5 percent. However, the EPA’s review of the testing 

agreement indicates that an oxygen content of 20.5 percent, rather than 20.4 percent, was the 

threshold for testing.

Comment 3: Commenter 0244 supported using PM as a surrogate parameter for non-Hg HAP 

from tunnel kilns in the sanitaryware subcategory. 

Commenter 0247 proposed that the ceramic tile subcategory be allowed to demonstrate 

compliance using the currently proposed PM surrogate limit, a new total non-Hg HAP limit, or 

new metal-by-HAP metal emission limits. The commenter contended that limiting the ceramic 

tile subcategory to a PM surrogate standard unnecessarily limits the flexibility of the industry to 

comply.

According to Commenter 0247, EPA’s decision to not provide this flexibility was questioned 

during the Interagency Review pursuant to Executive Order 12866. Interagency Commenter

asked “For the BSCP source category, EPA explained that some owners/operators may find that 

meeting a total non-Hg HAP metals limit is less costly than meeting a PM limit and provided 

that flexibility of using an alternative compliance option for total non-Hg HAP metals. Does 

EPA have reason to believe that would not be the case for this source category? Or is there some 

other reason why EPA is only providing the option of meeting the PM standard as a surrogate for 
22

non-Hg HAP metals?” The EPA responded by saying “We do not have the data needed to 

establish an alternative non-Hg HAP metals numerical limit for the clay ceramics source 

category.”6 The commenter stated EPA never identified in writing what data it lacked and argued 

that EPA’s dismissal of this question failed to satisfy its obligations under this and other 

Executive Orders. According to the commenter, the only remedy for this failure is for EPA to 

reinitiate this rulemaking and for EPA to discharge its legal obligations by providing a 

substantive response.

Commenter 0247 believed the EPA’s decision not to adopt individual metal HAP limits was due 

to issues related to the manganese (Mn). The commenter noted the EPA rejected some of the 

industry’s Mn floor tile kiln and glaze line stack testing emissions results because of Mn

contamination.7 The commenter stated that since many other Mn results were affirmed, EPA’s 

response to the interagency comment omitted material data and facts in EPA’s possession. The 

commenter further contended that EPA’s Mn contamination findings are based on a statistical 

tool that has not been explained. Come stack test runs that did not suffer from Mn contamination 

were declared invalid, while others suffering from alleged Mn contamination were declared 

valid. The commenter also stated they were not made aware of these Mn concerns nor given the 

opportunity to address them. When EPA determined that a test run suffered from Mn

contamination, the commenter stated the EPA arbitrarily determined that no other HAP metal 

data from that test run, except Hg, was valid and usable. The commenter argued the EPA 

discarded valid results and thereby reduced the number of eligible data points for each HAP 

metal in the respective MACT floor and thereby biased the pool. The commenter asserted that 

the proposed PM surrogate emission limits are arbitrary and contrary to law, since the EPA has 

the data to set total non-Hg HAP metals emission limitation for this subcategory.

Commenter 0247 argued that the proposed limits are arbitrary and capricious, because the EPA 

cannot set supportable total PM surrogate emission limits where the EPA lacks the data to set 

total non-Hg HAP metals emissions limits. The commenter also challenged EPA’s use of Hg

data from Mn contaminated test runs. The commenter stated the docket contains no explanation 

for why Hg data were used, while all of the other HAP metals were excluded for Mn

contaminated test runs.

The commenter stated that EPA allowed the brick and structural clay products (BSCP)

subcategory two options for the Hg limit (i.e., micrograms per dry standard cubic meter 

(μg/dscm) corrected to 7 percent oxygen or kilograms (kg)/mass in 79 FR 75683 (Dec. 18, 

2014)(proposed to be codified as 40 CFR 63.8405, incorporating Table 1 of 40 CFR part 63, 

subpart JJJJJ)), but provided only one option for the ceramic tile subcategory. The commenter 

argued that this disparate treatment is arbitrary and capricious. Expanding the available units of 

measure, the commenter argued, creates incentive for the subcategory to attempt to lower the 

HAP content of its glazes. The commenter stated that EPA must revisit and re-sort the data 

 6 Docket Item No. EPA-HQ OAR-2013-0290-0237, Summary of Interagency Working Comments on Draft 

Language under E012866/13563, at page 177.

7 Docket Item No. EPA-HQ OAR-2013-0290-0224, Test Data Used in Clay Ceramics Proposed Rule, at page 5 and 

Table 1 (Nov. 6, 2014)
23

ranking for each HAP metal for each of the proposed alternative units of measure to assure the 

designation of the best performing source is accurate.

Response 3: The compliance flexibility provided to the BSCP source category (including nonHg HAP metals limit, units of measure options) was solely related to Small Business Regulatory 

Enforcement Fairness Act (SBREFA) concerns, specifically reducing the regulatory burden of

the numerous small entities in the BSCP category. It was not related to the availability or 

unavailability of HAP metals data in the Clay Ceramics source category. It should be noted that 

there are no major source small entities in the Clay Ceramics source category. In addition, at the 

time of proposal, all Clay Ceramics sources were either estimated not to be impacted by the 

emission limits in the proposed rule, or had become synthetic area sources not subject to the 

major source proposed rule. Consequently, the EPA concluded that no additional compliance 

flexibility was necessary or warranted for the Clay Ceramics source category. The arguments 

presented by the commenter do not change this conclusion.

The EPA disagrees that valid results were excluded. There was a testing issue with Mn

contamination. Manganese contamination was identified by a simple calculation of the ratio of 

the back half Mn mass to the front half Mn mass. If the ratio was over 5, that test run was 

assumed to have Mn contamination, and were excluded. If Mn was determined contaminated 

then the total HAP metal run value was not valid. Unlike the total HAP data, the Hg data was 

valid because the Mn contamination was not included in the calculation of the Hg data.

Comment 4: Commenter 0244 stated that units for the PM and Hg emission limitations for 

sanitaryware tunnel kilns in Table 1 to the proposed rule should be per “ton greenware fired,” not 

per ton fired product. This is consistent with how process data were reported to EPA for the ICR.

Response 4: The EPA agrees with the commenter’s request for a clarification in the units of 

measure for the PM and Hg emission limits and has revised the sanitaryware emission limits 

listed in Table 1 for the final rule as suggested. 

Comment 5: Commenter 0244 supported the use PM as a surrogate parameter for non-Hg metal 

HAP for sanitaryware glaze spray booths. The commenter requested that the unit of measure be 

clarified as “per ton first fire glaze sprayed (dry weight basis),” so there are no 

misunderstandings about the required process data. This is the same unit of measure as reported 

to EPA per ICR testing.

Conversely, Commenter 0247 stated that the proposed NESHAP should provide the opportunity 

for the regulated facility to choose among units of measure. The commenter noted that Equation 

2 of proposed 40 CFR 63.8595(f), as reflected on Tables 1 and 6 (proposed to be codified in 40 

CFR 63 subpart KKKKK, Tables 1 and 6) and all other relevant provisions of the proposed 

NESHAP, express the PM surrogate emission limit for the glaze line with glaze spray operations 

as “PM emissions must not exceed [.X] kg/Mg ([.Y] lb/ton) of glaze sprayed.” [79 FR 75655 

(col. 1), preamble Table 10, note b, 79 FR 75658, and 79 FR 75658, note b, and preamble Table 

11, 79 FR 75658 (Dec. 18, 2014)]

Commenter 0247 proposed that the emissions limit for PM surrogate emissions from a ceramic 

tile glaze line with glaze spray operation be expanded to allow compliance to be determined on a 
24

mass of HAP per ton of glazed tile production-basis as an alternative to the units of measure 

proposed by EPA. The commenter noted that EPA proposed this approach for the BSCP 

subcategory in a PM context analogous to this one. The commenter argued that EPA must revisit 

and re-sort the PM emissions data for the different units of measure to identify the best

performing source. The commenter knew of no reason and nothing in the EPA docket that 

suggests why EPA could not or should not extend this flexibility to ceramic tile glaze lines. The 

commenter contended that a failure to do so would be arbitrary and capricious.

Response 5: The EPA appreciates Commenter 0244’s support for the PM surrogate for 

sanitaryware glaze spray booths. The EPA agrees with the commenter’s request for a 

clarification in the units of measure for sanitaryware glaze spray booths and has revised Tables 1 

and 6 as suggested.

The EPA does not agree with Commenter 0247’s request for an equivalent limit for ceramic tile 

glaze lines in units of mass of HAP per ton of glazed tile production. Different glazes contain 

different types and amounts of HAP metals, so a single emission limit would not be 

representative of all the possible glazes that could be used in the process, and requiring sources 

to meet a different limit depending on the type of glaze used would be extremely burdensome to 

the industry. For this reason, the EPA is not adding the requested equivalent limit for ceramic tile 

glaze lines to the final rule.

6.2 Type of Standard

Comment 1: Three commenters (0244, 0246, and 0247) proposed a work practice standard in 

lieu of an emission limitation for D/F.

Commenters 0246 and 0247 argued there is no test method that will produce valid measurements 

of D/F emissions from the ceramic tile sector. Commenters 0246 and 0247 recommended the 

EPA adopt work practice standards if they regulate D/F emissions from ceramic tile kilns and tile 

dryers. The commenter suggested operators be required to fire their ware above 450 degrees C 

and operate tile dryers below 200 degrees C. They noted that EPA stated in a memorandum that

a temperature range of 200-450 degrees C is “conducive” to the formation of D/F. [EPA Docket 

no. 229, at page 2 (Nov. 6, 2014), citing Characterization of the Ceramic Manufacturing 

Industry, RTI Memorandum Abraczinskas and Marinshaw (Dec. 3, 1999)]. While the 

commenters disagreed that there is any temperature at which D/F is formed during tile 

production, they were prepared to accommodate EPA by accepting a work practice standard 

based on these temperature ranges. They noted that temperature records recorded by existing 

process control equipment could be maintained as continuous parameter monitoring systems 

(CPMS). The commenters supported this approach because they believe it would alleviate flaws, 

omissions and issues with Method 23.

Commenter 0244 opposed the proposed D/F emission limit for tunnel kilns in the sanitaryware 

sector and recommended it be replaced with a work practice standard. The EPA’s analysis of the 

D/F test data for brick kilns determined that more than 55 percent of the data represented non 

detects, and so qualified for a work practice standard, while only 25 percent of sanitaryware kiln 

data represented non detects. (See Table 4 in November 6, 2014 memo from RTI International to 

EPA (Telander) titled “Determination of ‘Non-Detect’ Test Data for Clay Ceramics Proposed 
25

Rule.”) According to Commenter 0244, brick kilns only conducted 2-hour test runs for D/F for 

the ICR, while sanitaryware kilns completed 4-hour test runs. The commenter stated it is 

reasonable to presume that a much higher proportion of sanitaryware test data would be nondetect if only 2-hour test runs were performed. The commenter asserts that the number of nondetects could have exceeded the 55 percent non-detect threshold for allowing work practices. 

The commenter argued that it is inappropriate to require different testing methodologies (2-hour 

sampling runs vs. 4-hour sampling runs) when those methodologies result in significantly 

different compliance requirements for the same HAP.

Commenter 0244 stated that sanitaryware facilities have been shown to only emit HAP in area 

source quantities. (See Table 8 in the November 6, 2014 memo from RTI International to EPA 

titled “Development of Cost and Emission Reduction Impacts for the Clay Ceramics NESHAP.”)

of less than 30 milligrams (mg)/kiln/year (80 μg/kiln/day). While it’s possible to measure this 

low level of emissions, the commenters argued it is not practical to control emissions at such 

trace concentrations. For this reason, Commenter 0244 asserted that a work practice standard for 

sanitaryware kilns similar to the work practice standard for brick kilns is justifiable for D/F.

Response 1: The EPA disagrees with Commenter 0244’s assertion that EPA allowed brick 

facilities to conduct 2-hour test runs for D/F while requiring sanitaryware facilities to conduct 

4-hour test runs. We checked all section 114 test requests and all available electronic reporting 

tool (ERT) files and test reports of the stack tests conducted by industry in response to the test 

requests. All sources were required to conduct 4-hour test runs for D/F, and all D/F test results 

were documented as based on 4-hour test runs. Based on EPA information, there is no 

inconsistency between brick and sanitaryware in the length of D/F test runs required or 

conducted.

Regarding the request for a D/F work practice standard, a testing program conducted under the 

2010 section 114 survey detected D/F in most test runs at all of the clay ceramics facilities tested, 

unlike the tests conducted at BSCP facilities. Therefore, there is no justification for replacing an 

emission limit with a work practice standard. The commenters’ request for a work practice 

standard is denied.

Comment 2: While Commenter 0244 supported the health-based emission limits for HF and 

HCl in the proposed rule, the commenter questioned why similar limits were not evaluated for 

the other HAP (e.g., Hg and D/F). Since acid gases represent 99.3 percent of all HAP emitted 

from tunnel kilns per Section II.D of the preamble and tunnel kilns emit only trace quantities of 

dioxin/furan and Hg, Commenter 0244 asserted that health-based limitations, rather than 

emission floors, may be also appropriate for tunnel kilns, especially since EPA has already 

documented that sanitaryware facilities emit only area source quantities of HAP.

Response 2: The EPA does not agree with the commenter’s request for health-based emission 

limits for D/F and Hg. Health-based emission limits can only be established for threshold 

pollutants. Known, probable and possible carcinogens cannot be categorized as threshold 

pollutants. D/F is a probable human carcinogen, and some Hg compounds (e.g., methylmercury) 

are considered possible human carcinogens. Therefore, health-based limits cannot be established

for D/F and Hg. 
26

Comment 3: Commenter 0244 opposed the emission limitation for Hg and requested it be 

replaced with a work practice standard, similar to the dioxin/furan work practice standard 

proposed for brick kilns in the proposed Brick MACT rule (Subpart JJJJJ). Tunnel kilns have 

been shown to only emit HAP in area source quantities. (See Table 8 in the November 6, 2014 

memo from RTI International to EPA titled “Development of Cost and Emission Reduction 

Impacts for the Clay Ceramics NESHAP.”) This memorandum shows Hg is emitted at a rate of 

less than 3 pounds (lb)/kiln/year (less than 3.5 grams/kiln/day), and while it is possible to 

measure this low level of emissions, it is not practical to control emissions at such trace 

concentrations. The commenter asserted that a work practice standard similar to the one 

proposed for dioxin/furan for brick kilns is justifiable for sanitaryware kilns. This work practice 

could also include a requirement for inside or covered storage of raw materials at each 

sanitaryware plant to prevent additional Hg contamination from atmospheric fallout.

According to the commenter, sanitaryware plants do not use any Hg-containing additives and 

that while it may be possible that Hg is a trace contaminant in the raw materials, the Hg more 

likely comes from exposure of raw materials to atmospheric Hg fallout from mining and 

processing activities. Atmospheric fallout of Hg is a confirmed environmental process (i.e., sizerelated fish consumption advisories for lakes all over the U.S. due to Hg levels in certain species 

caused by atmospheric fallout). The process of mining clays and raw materials, and the outside 

storage and processing, exposes the raw materials to atmospheric fallout of Hg, which is likely 

the single biggest factor in a raw material’s Hg content. All raw materials are stored indoors or in 

closed vessels once received at a sanitaryware plant, and there is no opportunity for additional 

Hg contamination from atmospheric fallout. Sanitaryware facilities have no control over how 

raw materials are mined, processed, and stored by suppliers, and they should not be held 

accountable, through Hg emission limitations, for such potential contamination issues. The 

commenter stated that indoor storage of raw materials at sanitaryware facilities is a feasible work 

practice standard to limit Hg emissions from first-fire tunnel kilns and should be included in this 

rule in lieu of Hg emission limitations.

Response 3: The EPA does not agree with Commenter 0244’s request for work practice 

standards for Hg for sanitaryware tunnel kilns. Under CAA section 112(h), the EPA may set 

work practice standards in place of an emissions standard where it is not technologically or

economically feasible to prescribe or enforce an emission standard. In this case, to support their 

contention that work practices are appropriate for Hg, the commenter needs to demonstrate that it 

is technically and economically infeasible to measure Hg from sanitaryware tunnel kilns. Based 

on available performance test results for sanitaryware tunnel kilns, work practice standards are 

not appropriate for Hg due to the levels of Hg found in the performance tests. There was only 

one facility that had non-detect levels from the laboratory. However, those detection limits were 

higher than a test that had detectable values. Consequently, it is technologically feasible to 

measure Hg from sanitaryware tunnel kilns. Based on the costs estimated for Method 29 testing 

of sanitaryware tunnel kilns, it is also economically feasible to measure Hg from sanitaryware 

tunnel kilns. Therefore, there is no justification under section 112(h) to establish work practice 

standards in place of emission limits.

Comment 4: Commenter 0244 supported the option to allow emissions averaging across 

existing tunnel kilns and glaze spray booths for all HAP with applicable emission limits. While 

most of the criteria EPA cited for this alternative seemed reasonable, the commenter stated that 
27

the requirement to develop an emissions averaging plan and submit it for approval by the 

regulatory authority was unnecessary. Averaging across similar sources is not a complicated 

endeavor, and asking a regulatory authority to review and approve such a plan would put this 

alternative out of reach for the facility if the approving authority does not act on the submittal in 

a timely manner. The regulated entity would have no means by which to prompt a response from 

the authority on this matter.

The commenter also did not support the use of a 10 percent discount factor for averaging. There 

are many NESHAP in which EPA allows averaging across process lines, such as the Reinforced 

Plastics Composites NESHAP, which do not include any kind of safety or discount factor, and 

the commenter argued that no such factor is needed for this proposed rule. The commenter 

asserted that there are safety factors already incorporated into the rulemaking and standard 

setting process and argued that the proposed 10 percent factor offers no practical additional 

environmental protection and should be excluded, particularly since sanitaryware facilities emit 

only area source quantities of HAP.

Response 4: The EPA does not agree with Commenter 0244’s request for emissions averaging 

across tunnel kilns and glaze spray booths for their source category. The emissions averaging 

option discussed at proposal was meant only for the BSCP source category, as an alternate option 

for addressing SBREFA concerns, specifically reducing the regulatory burden of the numerous 

small entities in the BSCP category. It was never meant to be considered for the Clay Ceramics 

source category, which has no major source small entities. In addition, at the time of proposal, all 

Clay Ceramics sources were either estimated not to be impacted by the emission limits in the 

proposed rule, or had become synthetic area sources not subject to the major source proposed 

rule. Consequently, the EPA concluded that no additional compliance options (such as emissions 

averaging) were necessary or warranted for the Clay Ceramics source category. The arguments 

presented by the commenter do not change this conclusion.
28

7.0 MACT Floors

7.1 Determining Sources in Floor Pool

The public comments on determining sources in the MACT floor pool can be found in section 

VI.B of the preamble to the Clay Ceramics final rule.

7.2 UPL

Comment 1: Commenter 0248 stated the EPA proposed to use the UPL to set floor standards, 

even after the D.C. Circuit remanded the EPA’s use of that method in NACWA. 734 F.3d at 

1139-45. The commenter stated the EPA’s use of the UPL in this rule is unlawful, arbitrary, and 

capricious for the following reasons.

Commenter 0248 stated the CAA section 112(d)(3) unambiguously requires floors to reflect the 

“average” emission level achieved by the relevant best-performing sources. The commenter 

stated by using the word “average,” Congress demanded a measure of ordinary, usual 

performance -- a central tendency -- of the “emissions limitation achieved by the best performing 

12 percent of the existing sources.” See Webster’s Seventh New Collegiate Dictionary at 61 

(1971) (defining “average” to mean “equaling an arithmetic mean,” “approximating or 

resembling an arithmetic mean in being about midway between extremes,” or “not out of the 

ordinary”). See, e.g., Leocal v. Ashcroft, 543 U.S. 1, 9 (2004) (“When interpreting a statute, we 

must give words their ‘ordinary or natural’ meaning.”) (quoting Smith v. United States, 508 U.S. 

223, 228 (1993)).

Commenter 0248 stated in the EPA’s previous attempt to establish a rule for brick and clay 

ceramics sources, the EPA formally adopted an “interpretation of average emission limitation” 

acknowledging “that it is a measure of central tendency, such as the arithmetic mean or the 

median.” 68 FR 26700; see also 59 FR 29196, 29199 (Mar. 9, 1994) (formal rulemaking 

establishing that “EPA construes the word ‘average’ in section 112(d)(3) to authorize the Agency 

to use any reasonable method, in a particular factual context, of determining the central tendency 

of a data set”). The commenter stated according to the EPA, “Congress spoke with clarity in 

[section 112(d)(3)(A)] of the Clean Air Act,” and that the section “lends little support for an 

interpretation under which standards might be set at the emission limitation achieved by the 

worst performing member of the best performing 12 percent of existing sources,” while the Act’s 

legislative history “points strongly in the opposite direction” from any such “worst-of-the-best” 

construction. 59 FR 29199.

Commenter 0248 stated the EPA has consistently reaffirmed that interpretation in its 

rulemakings. E.g., 68 FR 1276, 1286 (Jan. 9, 2003), (plywood); 67 FR 30848, 30853 (May 8, 

2002) (semiconductors); 66 FR 58,610, 58,618 (Nov. 21, 2001) (asphalt processing); 64 FR 

2611, 2612 (Jan. 15, 1999) (natural gas transmission & storage); 61 FR 48208, 48210 (Sept. 12, 

1996) (polymers & resins).

Commenter 0248 stated that CAA section 112(d)(3) also unambiguously requires that floors 

reflect the emission level actually “achieved” by the relevant best-performing sources (those with 

the lowest emission levels). Sierra Club, 479 F.3d at 880-81. The commenter stated the EPA 

may not override the floor requirements with its own notions about what is “achievable.” Id. at 
29

877-79, 880-81; Cement Kiln Recycling Coalition v. EPA, 255 F.3d 855, 861 (D.C. Cir. 2001). 

The commenter stated speaking consistently in the past tense, Congress used the word 

“achieved” four times in this provision. The commenter asserted that Congress meant what it 

said: “section [112](d)(3) requires floors based on the emission level actually achieved by the 

best performers.” Sierra Club, 479 F.3d at 880-81.

Commenter 0248 stated to satisfy the CAA, therefore, existing source floors must reflect the 

average (i.e., a “central tendency”) of the emission levels “actually achieved” by the relevant 

best-performing sources. The commenter stated floors must be “‘demonstrate[d] with substantial 

evidence - not mere assertions’ ....” Ne. Md. Waste Disposal Auth. v. EPA, 358 F.3d 936, 954 

(D.C. Cir. 2004) (quoting Cement Kiln, 255 F.3d at 866 and Sierra Club v. EPA, 167 F.3d 658, 

662 (D.C. Cir. 1999)).

Commenter 0248 stated although CAA section 112(d)(3) unambiguously requires floors to 

reflect the “average” emission level actually “achieved” by the best performing 12 percent of 

units, the EPA set floors at the upper prediction limit for the sources it claimed were the best 

performers.

Response 1: The EPA disagrees with the commenter. The NACWA court did not find the UPL to 

be an arbitrary approach, but simply asked for a better explanation from the Agency. The UPL 

memorandum in the docket for this rule provides the explanation of what the UPL represents 

sought by the NACWA Court. It also explains why the UPL is representative of the level of 

performance achieved by the best performing unit or units. The court did not state that the 

“average emissions limitation achieved by the best performing 12 percent” must be equal to the 

mean of the available data, as suggested by the commenter, and in past decisions the court has 

upheld that it is appropriate for EPA to account for variability when establishing numeric MACT 

standards. See Mossville Environmental Action Now v. EPA, 370 F.3d 1232, 1241-42 (D.C. Cir. 

2004). Thus, the EPA maintains the UPL approach to calculate the MACT floors for Brick 

tunnel kilns in the final rule. Please see the “Use of the Upper Prediction Limit for Calculating 

MACT Floors” memo (EPA-HQ-OAR-2013-0290-0217) found in the docket for this rule, for the 

EPA’s justification of the UPL approach.

Comment 2: Commenter 0248 stated as the EPA itself made clear, the upper prediction limit is 

the level that a best performing facility has one in 100 chance of exceeding. MACT Floor Memo 

- Brick at 3; MACT Floor Memo - Clay Ceramics at 3. The commenter stated in other words, it 

is a level that the EPA expects 99 out of 100 future compliance tests by any of the best 

performing facilities in the top 12 percent to “fall below.” 79 FR 75635. The “UPL estimates 

what the upper bound of future values will be.” MACT Floor Memo - Brick at 3; MACT Floor 

Memo - Clay Ceramics at 3.

Commenter 0248 stated the EPA’s UPL is not an “average” or a measure of “central tendency.” 

The commenter stated it is, as its name indicates, an “upper limit” -- the emission limitation that 

every member of the best-performing 12 percent will “fall below,” virtually all of the time. 79 

FR 75635; UPL Memo at 5 (describing UPL as “a limit that can be met by all the existing 

sources in the floor at all times”). The commenter stated such a once-in-100 emission level is not 

a measure of “average” emissions any more than a hundred-year flood can be a measure of 

“average” water levels; thus, the EPA cannot support its claim that the UPL creates an estimate 
30

of the emission limitation “achieved by the average source.” UPL Memo at 10. The commenter 

stated the EPA does not adequately explain how the UPL is an “average.”

Commenter 0248 stated given its ordinary meaning and the meaning the EPA itself has adopted 

through notice-and-comment rulemaking, “the word ‘average’ in [section 112(d)(3)],” allows the 

EPA only to use a “reasonable method ... of determining the central tendency of a data set.” 59 

FR 29199. The commenter stated a level that the EPA expects 99 out of 100 future tests by any 

source in the top 12 percent to “fall below” is not a measure of the “central tendency” of the 

emission levels achieved by this group of sources; rather, it is a measure of one extreme, an 

“upper bound” on what any of those sources might emit in a future test. MACT Floor Memo -

Brick at 3; MACT Floor Memo - Clay Ceramics at 3. The commenter stated the UPL does not, 

as the EPA claims, estimate an emission limitation “achieved by the average source.” 79 FR 

75636. The commenter stated a floor that the EPA expects even the worst performing source 

within the top 12 percent to meet in 99 out of 100 future tests is not, in any sense, representative 

of “average” source in that group. See Natural Res. Def. Council v. Daley, 209 F.3d 747, 754 

(D.C. Cir. 2000). The commenter stated the UPL does not aim for an “average,” it aims for an 

entirely different target: an “upper limit” that every source within the top 12 percent will meet at 

virtually all times.

Response 2: The EPA disagrees with the commenters that the UPL is not representative of the 

average emissions limitation achieved over time by the best performing sources or sources. The 

CAA leaves to EPA’s discretion the manner in which to calculate “the average emissions 

limitation achieved” by the best performing sources. The EPA has used the average of the lowest 

emission data from the top performing 12 percent of data available in calculating the MACT 

floors. The EPA has then incorporated variability in developing the final MACT floor limits in 

the final rule. The EPA has conducted traditional outlier analyses to remove from the data set 

any data determined to be statistical outlier data. The EPA believes that the data incorporated in 

the MACT floor pool represent the variability present at the various brick and clay ceramics 

manufactures.

As stated in the memorandum entitled “Use of the Upper Prediction Limit for Calculating 

MACT Floors” (Docket No. EPA-HQ-OAR-2013-0290-0217) (“UPL memorandum”), in “the 

context of development of MACT floors, the UPL is a value, calculated from a dataset, which 

identifies the average emissions level that a source or group of sources is meeting and would be 

expected to meet a specified percent of the time that the source is operating. That percent of time 

is based on the confidence level used in the UPL equation. For a single best controlled emission 

source that serves as the basis for a new source MACT floor, the 99 percent UPL is the 

emissions level that the source would be predicted to be below during 99 out of 100 performance 

tests, including emissions tests conducted in the past, present, and future, based on the short term 

stack test data available for that source. It is important to note that the UPL does not represent 

the worst emissions performance of the best performing units at any time, but rather the average 

level expected to have been achieved over time, as the first element of the UPL equation is the 

average of the short-term emissions test data from the best performing units. 

In other words, the 99 percent UPL is the level of emissions that we are 99 percent confident is 

achieved by the average source represented in a dataset (in the case of MACT standards, the 
31

dataset representing the performance of the best performers as specified in the CAA) over a 

long-term period based on its previous, measured performance history as reflected in short-term 

stack test data.”

Comment 3: Commenter 0248 stated the interpretation of the term “average” that the EPA 

advanced in this rulemaking is internally inconsistent. The EPA “interprets the average to mean 

the average emissions over time.” UPL Memo at 3. The EPA also claimed that the UPL 

represents “the average level expected to have been achieved over time” by the relevant sources, 

id. at 4, and represents a level of emissions the EPA does not expect the average source to 

exceed. Id. at 6. The EPA conceded the upper prediction limit is an “upper limit” on the relevant 

sources’ emissions. Id. at 3. Yet the EPA also implied that the upper prediction limit may satisfy 

the Act by describing the “average level” achieved by the best performers over time, Id. at 4-5, 

and at others, the EPA suggests it satisfies the Act by describing the emission level constantly 

achieved by a single “average source.” Id. at 4, 10. The commenter stated claiming that the same 

statutory provision means different things “diverges from any realistic meaning of the statute.” 

Massachusetts v. Dep’t of Transportation, 93 F.3d 890, 893 (D.C. Cir. 1996). The commenter 

stated it is also arbitrary. Dep’t of Treasury v. FLRA, 739 F.3d 13, 21 (D.C. Cir. 2014) (“set[ting] 

forth two inconsistent interpretations of the very same term” is arbitrary and capricious).

Commenter 0248 stated the interpretation of the term “average” that the EPA advanced in this 

rulemaking is a departure from, and directly conflicts with, its own long-standing interpretation 

of the Act, which it adopted through notice-and-comment rulemaking and reaffirmed many 

times. 59 FR 29199. The commenter stated although the EPA previously rejected any 

understanding of the word “average” that would encompass an emission limitation “achieved by 

all members of the best performing 12 percent,” id. at 29,197, that is precisely the function of the 

UPL. The commenter stated the EPA does not acknowledge its prior interpretations, nor does it 

explain its reversals. See FCC v. Fox Television Stations, 556 U.S. 502, 515 (2009) (agencies 

may not “depart from a prior policy sub silentio”); Mountain Commc’ns v. FCC, 355 F.3d 644, 

648-49 (D.C. Cir. 2004) (action arbitrary where agency “changed direction without explanation, 

indeed without even acknowledging the change”).

Response 3: The EPA interprets the average to mean the average emissions over time, based on 

both the calculated average of all emissions test data from the best performing source or sources 

and the available information regarding the variability of emissions. The UPL, which EPA uses 

to account for variability among the best performing sources, reflects an upper limit for the 

emissions of those sources at times other than when the emissions tests occurred. This not only is 

a prediction of the emissions performance of those sources in tests conducted in the future, but is 

also an indication of the range of current average emissions performance of those units. 

Comment 4: Commenter 0248 stated the authorities on which the EPA seeks to rest its claim 

that the upper prediction is an average confirm that the upper prediction limit is not an average. 

See UPL Memo at 4 (citing Luko & Neubauer, Statistical Intervals Part 2: The Prediction 

Interval, Standardization News (October/Nov. 2011) (http://www.astm.org/standardizationnews/datapoints/ statistical-intervals-part-2-so11.html); Gibbons & Coleman, Statistical Methods 

for Detection and Quantification of Environmental Contamination (2001)). Luko and Neubauer 

state that the prediction limit is “different” from an “interval for the mean with some degree of 

confidence.” Luko & Neubauer at 1. Likewise, Gibbons and Coleman expressly note the 
32

difference between a prediction limit and a “confidence interval for the mean.” Gibbons & 

Coleman at 31. The commenter stated these sources further point out that prediction limits 

provide “wider” results -- that is, higher upper limits -- than an estimate of the mean, in part 

because they reflect “the variability of future observations,” rather than just the variability in 

sources’ actual performance. Id.

Commenter 0248 stated the EPA claimed that its upper prediction represents an average over 

time because “the first element of the UPL equation is the average of the short-term emissions 

test data from the best performing units.” UPL Memo at 4. The commenter stated the mere fact 

that the first element of the equation is an average does not demonstrate that the final product of 

the equation is the average over time. The EPA provided no basis on which it could reasonably 

conclude that just because its upper prediction equation starts with an average and then adds a 

number to “address variability,” this equation yields the average over time.

Commenter 0248 stated the EPA also argued that because the average is in the first half of the 

equation, the UPL “goes up or down” with average emissions. Id. at 11. The EPA also admitted, 

however, that the upper prediction also goes up or down with factors that are entirely unrelated 

to the average: “the number of runs in the dataset” and “the number of runs averaged for each 

emissions test.” Id.; see also NACWA, 734 F.3d at 1144-45. The commenter stated that the record 

shows that the number of runs in a dataset can make the EPA’s upper prediction go up (i.e., get 

worse) even when the average emissions achieved go down (i.e., get better). See NACWA, 734 

F.3d at 1144.

Response 4: As discussed above, the NACWA court did not state that the “average emissions 

limitation achieved by the best performing 12 percent” must be equal to the mean of the 

available data, as suggested by the commenter, and in past decisions the court has upheld that it 

is appropriate for EPA to account for variability when establishing numeric MACT standards. 

See Mossville Environmental Action Now v. EPA, 370 F.3d 1232, 1241-42 (D.C. Cir. 2004). 

Also the CAA leaves to EPA’s discretion the manner in which to calculate “the average 

emissions limitation achieved” by the best performing sources.

Comment 5: Commenter 0248 stated the EPA claimed that an emissions test dataset from 

another rulemaking demonstrates that the UPL for that dataset “represents the average emission 

level achieved by the best performing sources.” UPL Memo at 12-15. The commenter stated that 

EPA conceded, however, “no source among the best performing 12 percent had an overall 

average above the 99 percent UPL,” and only the worst performing source in the top 12 percent 

had even one “3-run test average above the UPL.” Id. at 14. The commenter asserted that to 

argue that just because one test result is higher than the UPL that the UPL is an “average” is like 

arguing that because a river will sometimes reach its 100-year flood level, the 100-year flood 

level is an “average” height for the river. The commenter stated that four units had “one test run 

value” above the EPA’s upper prediction, id., is irrelevant. The commenter stated according to 

the EPA, the UPL produces an estimate of a 3-run test average, not a single “test run.” Id. The 

commenter asked if, as the EPA asserts, the UPL predicts the emission limitation consistently 

achieved by the “average source” among the best performers, id. at 4, 10, or (as the EPA also, 

and contradictorily, contends) the “average emissions limitation” achieved by the best 

performing units - why do all the best performers fall below it, virtually all of the time.
33

Response 5: The Case B example from the UPL Memo is an example from sewage sludge 

incinerators, where there are 150 existing units in the multiple hearth subcategory nationwide 

with 18 sources in the MACT floor pool. In general, the closer each individual unit’s average is 

to the overall MACT floor pool average, the greater the likelihood that the unit will be able to 

meet the calculated UPL MACT floor. In the Case B example provided by EPA in the UPL 

Memo located in the docket for this rule, 13 out of 18 sources had a unit average that was less 

than the average of the overall MACT floor pool. For the other 5 units of the 18 their average 

was above the overall MACT floor pool, thus their ability to meet or not meet the calculated 

UPL depends on the quantity of the variability component of the UPL equation being added to 

the average component of the UPL equation. The variance component of the UPL equation is 

dependent on the variability of the test runs from the entire MACT floor pool. In the Case B 

example provided by the EPA in the UPL Memo, the variance component added enough 

variability that all of the 18 units of the MACT floor pool could meet the calculated UPL. That is 

not always the case for every UPL calculation, adding the variance component to the average 

component in the UPL equation does not always result in “all the best performers falling below 

the calculated UPL.” For MACT floor pools that contain sources with little variability between 

all the runs resulting in a low variability component, the likelihood of all the sources in the pool 

being able to meet the calculated UPL decreases. For MACT floor pools that contain sources 

with a great amount of variability between all the runs resulting in a high variability component, 

the likelihood of all the sources in the pool being able to meet the calculated UPL increases.

Comment 6: Commenter 0248 stated by setting floors at the upper prediction limit, the EPA also 

contravenes CAA section 112(d)(3)’s unambiguous requirement that floors reflect what the best 

sources “actually achieved.” Sierra Club, 479 F.3d at 880-81. The commenter stated the statute 

unambiguously requires floors to reflect what the best performing sources “achieved,” not what 

EPA predicts they will achieve in the future. See Sierra Club, 479 F.3d at 880-81. The 

commenter stated the UPL is not a measure of the performance of the source but a prediction 

value and does not represent the current sources; the UPL does not merely address the variability 

in the emission levels that sources actually “achieved”; rather, it further inflates the floors to 

ensure that they will be higher than the level the EPA is 99 percent confident no source in the top 

12 percent will exceed in a hypothetical “future” compliance test. The commenter stated by 

requiring floors to reflect what the relevant best sources actually “achieved,” however, the text of 

CAA section 112(d)(3) eliminates any discretion to set floors at levels EPA expects the relevant 

sources not to exceed in “future” compliance tests. The commenter stated for the new source 

floors, the UPL does not reflect what any source actually “achieved,” but rather is a value that 

the EPA expects the best controlled source to always fall below; the UPL approach is contrary to 

the CAA’s plain meaning.

Commenter 0248 stated Congress enacted section 112(d)(3) to put an objective constraint on the 

EPA’s discretion. New Jersey v. EPA, 517 F.3d 574, 578 (D.C. Cir. 2008). The commenter stated 

by substituting its subjective upper-limit-prediction for an objective measure of what sources 

have “actually achieved,” Sierra Club, 479 F.3d at 880-81, the EPA impermissibly “nullifies [a] 

textually applicable provision[] meant to limit its discretion.” Whitman v. Am. Trucking Ass’ns, 

531 U.S. 457, 485 (2001).

Commenter 0248 stated to promulgate a non-arbitrary rule, “EPA ‘must demonstrate with 

substantial evidence - not mere assertions’” that its floors satisfy the statute. NACWA, 734 F.3d 
34

at 1131. The commenter stated nowhere in the record has the EPA demonstrated that its UPL is 

an accurate estimate of the “average” emission level that the relevant best sources have actually 

“achieved,” or that it reflects what the best controlled source “achieved in practice.” The 

commenter stated the UPL is neither the average emission level achieved by the best performing 

sources nor the emission level achieved by an average source; rather, it is a level the EPA 

expects sources in the top 12 percent -- including the worst -- to fall below in any future test, and 

the best controlled source to always fall below.

Commenter 0248 stated even if the EPA could base floors on what it thinks the best-performing 

sources will achieve in the future rather than what they actually achieved in the past -- which it 

cannot for the reasons given above -- the EPA’s formula assumes that sources’ future will vary 

randomly. The commenter stated that sources’ performance is not random but, rather, is 

constrained by the steps that different operators take to control their emissions, including fuels 

they choose to burn, controls they install, and the care with which they operate those controls. 

Sierra Club, 479 F.3d at 880-83; 67 FR 47907. The commenter stated the assumption that all 

variability is inherent variability over which operators have no control is unsupported and 

inaccurate; counting the effects of these factors as inherent variability results in floors that do not 

reflect the best source or sources’ actual performance. The commenter stated the EPA does not 

provide any explanation for its apparent assumption that sources’ actual emission levels will vary

to the full extent of the 99th percent UPL.

Response 6: The EPA disagrees with the commenter’s statement that the UPL does not reflect 

emission levels “actually achieved.” The commenter misunderstands the purpose of the UPL 

calculation. It is not intended to only predict the best performing sources’ future performance, 

although it can be used to do that. Rather, for the purpose of setting MACT standards, it is used 

to estimate the best performing sources’ current emissions over time, rather than during the very 

short-term periods measured during stack testing.

The EPA interprets “emissions performance,” as used in section 112(d)(3) to mean the emissions 

of a source over the long term, rather than just during a short-term stack test. This is a reasonable 

interpretation of the statutory directive that the MACT standard be no less stringent than the 

average emissions limitation “achieved by” the best performing sources, since the emissions 

level of a source is not expected to always be the same as it is during stack testing. The EPA thus 

uses the UPL to assess the emissions achieved and achievable, for a prescribed confidence level, 

by the source based on its tested performance at times other than when stack testing was 

conducted. This enables EPA to calculate the average emissions performance of the best 

performing sources over time. The EPA uses the UPL approach in its MACT floor analysis 

because it incorporates the average performance of the best performing sources and the 

variability of the performance during testing conditions. The commenter is incorrect that the 

UPL calculation results in an emissions level that the worst source in the top 12 percent of 

sources will fall below. As explained in the “Use of the Upper Prediction Limit for Calculating 

MACT Floors” memo (EPA-HQ-OAR-2013-0290-0217), the UPL calculation begins with the 

average emissions level of the best performing sources, and then applies a second step in order 

to account for the variability in emissions performance of those sources. For the development of 

the Hg floor, the variability of the raw material was also taken into account. The UPL represents 

the value which one can expect the mean of a specified number of future observations to fall 

below for a specified level of confidence based upon the results of an independent sample from 
35

the same population. Please see the “Use of the Upper Prediction Limit for Calculating MACT 

Floors” memo (EPA-HQ-OAR-2013-0290-0217) for the EPA’s justification of the UPL 

approach.

The EPA disagrees with the commenter regarding randomness of emissions from sources 

imposed by use of the UPL formula. Use of that formula provides a way to restrict the effect of 

randomness to a known range of values calculated from short term testing, as opposed to the 

commenter’s notion that the effect of randomness is varied and unknown. Of course, similar 

operation of the source, consistent with the conditions under which it was tested, is a necessary 

component of the UPL calculations; otherwise, the randomness to which the commenter refers 

could creep in. As the emission limits are established on a certain set of practices and operations 

associated with a successful performance test of the best-operating source, those good practices 

and operations are contained in the values calculated by the UPL and should also serve to reduce 

the randomness of which the commenter expresses concern.

Comment 7: Commenter 0248 stated the UPL is a particularly inaccurate representation of what 

the best source or sources “actually achieved” where the emissions dataset is small; as the D.C. 

Circuit has recognized, the results generated by the EPA’s upper prediction approach depend 

heavily “on the size of the dataset.” NACWA, 734 F.3d at 1144-45. The commenter stated a 

smaller dataset causes the EPA’s statistical approach to generate higher (i.e., weaker) floors. Id. 

The commenter stated in this record, the EPA “recognize[s] that the use of the UPL” for small 

datasets introduces “uncertainty” in the calculation of MACT standards. EPA, Approach for 

Applying the Upper Prediction Limit to Limited Datasets at 2 (Sept. 17, 2014), Docket Item No. 

EPA-HQ-OAR-2013-0291-0127 (hereinafter “Limited Datasets Memo - Brick”). The 

commenter stated the “number of values in a particular dataset[] is an important component of 

the UPL approach,” Id. at 1; the t-score (or z-score, depending on which equation is used) is used 

by the EPA to estimate the uncertainty and variability for a certain confidence level, and “is 

highly variable at the smallest sample sizes” and “can have a disproportionate effect, 

overwhelming the other components” of the UPL calculation. Id. at 2. The commenter stated 

moreover, the sample size itself is a separate variable in the EPA’s UPL equation, and as the 

sample size gets smaller, the UPL gets larger (all other variables being constant). Id. at 4. The 

sample size is a “key component” in the calculation of two other variables in the EPA’s UPL 

equation: the mean and variance; “larger sample sizes provide better estimates of the population 

mean and variance.” Id. The commenter stated also, the confidence level chosen by the EPA 

influences the t-score (or z-score), which in turn is “highly variable” where there is limited data. 

Id.

Commenter 0248 stated in light of the significant and pervasive uncertainty that small sample 

sizes introduce into the UPL calculation, the UPL cannot represent the performance that the best 

sources “actually achieved,” as the Act requires, where sample sizes are small; and the EPA is 

frequently faced with the task of establishing floors where it has limited data. The commenter 

stated for example, in these rules alone, the EPA identified 20 floors for which the EPA had 

fewer than 7 data points. See id. at 8; EPA, Approach for Applying the Upper Prediction Limit to 

Limited Datasets at 8 (Sept. 17, 2014), Docket Item No. EPA-HQ-OAR-2013-0290-0218 

(hereinafter “Limited Datasets Memo - Clay Ceramics”). The commenter stated the serious 

shortcomings in the UPL for small datasets alone highlights the need to abandon the UPL 

approach.
36

Commenter 0248 stated the EPA recognizes that the UPL generates higher and potentially 

inaccurate and unrepresentative floors where the sample size is smaller; yet to address this 

fundamental problem with the UPL approach, EPA proposes that for sample sizes of fewer than 

7, it will “further evaluate” the data in “one or more” ways “on a case-by-case basis” to check to 

see if “the uncertainty associated with a limited dataset does not cause the calculated emission 

limit to be so high” as to be illegal. Limited Datasets Memo - Brick at 6. The commenter stated 

the EPA offers few details as to how, exactly, it will know when the small sample size causes the 

UPL to be unacceptably “high,” except that the EPA will use its “experience” and “technical 

expertise” in its evaluation. Id. at 6-7. The EPA specifies no standards to guide this ad hoc 

evaluation.

Commenter 0248 stated the EPA’s proposed solution to the significant flaw in the UPL identified 

by the D.C. Circuit provides no assurance that the UPL will produce accurate limits. The 

commenter stated the EPA is asking that it be trusted to take a second look at an admittedly 

flawed formula and make sure it is “reasonable.” Id. at 7 (“we ... would ensure that the emission 

limit is reasonable”); id. at 6 (“The evaluation will include one or more of the following ...: 

confirming that the data distribution was selected correctly” and “ensuring that we use the most 

appropriate UPL equation.”). The commenter stated the reasonableness is not the legal standard: 

the EPA must demonstrate with “substantial evidence” that use of the UPL for small datasets 

represents what the best source or sources “actually achieved.” The commenter stated the EPA 

needs to do more than double-check its math to make such a showing where the standard-setting 

method being applied is undisputedly defective.

Commenter 0248 stated the EPA’s application of its approach to evaluating and addressing UPLbased floors derived from limited data shows how insufficient this evaluation is; of the twenty 

floors based on small datasets, the EPA concludes without much reasoning that no adjustments 

were warranted.

Commenter 0248 stated also, the EPA fails to rationally explain why sample sizes smaller than 7 

require further evaluation, but slightly larger sample sizes do not. The commenter stated the 

EPA’s own data demonstrates that uncertainty continues to decrease beyond 6 samples as the 

sample size increases. Id. at 3, 5-6 (showing a “7% reduction from 6 to 7 samples” and a “5% 

reduction from 7 to 8” samples). The commenter stated the EPA fails to point to any statistical 

reason why the uncertainty caused by sample sizes greater than 6 can be ignored; it is irrelevant 

that the test data itself may have some uncertainty, as the EPA points out: uncertainty elsewhere 

in the standard-setting process does not justify use of a method to account for variability that 

adds even more uncertainty to the outcome. The commenter stated if anything, additional 

uncertainty caused by the EPA’s proposal to use a UPL is less justifiable if it compounds 

existing concerns about accuracy.

Response 7: As discussed above, the EPA disagrees with the commenter’s statement that the 

UPL does not reflect emission levels “actually achieved,” including the UPL for limited datasets.

A limited dataset does not automatically mean that the calculated UPL is flawed and should not 

be used; however, given the potential impact of uncertainty due solely to the number of samples, 

it is appropriate for the EPA to assess all factors used in the UPL calculations when determining 

an emissions limit, so that the emissions limit reflects the average performance of the units upon 
37

which the limit is based. The basis for the 6 sample cut off for limited datasets was determined 

based on the effect of the sample size dependent component of the UPL equation, the t-statistic. 

As the Limited Dataset Figure 1 and Table 1 demonstrate, the t-statistic for sample sizes below 7 

have a greater value and thus a greater contribution to the UPL equation. The t-statistic for 

sample sizes at and above 7 start to level off and have a lesser contribution to the UPL equation. 

As such, the limited dataset cutoff was determined to be below 7 samples.

Please see the “Approach for Applying the Upper Prediction Limit to Limited Datasets” memo 

(EPA-HQ-OAR-2013-0290-0218) for more information regarding the UPL approach for limited 

datasets.

Comment 8: Commenter 0248 stated the EPA’s specific selection of the 99 percent UPL as 

opposed to a 95 percent UPL, a 90 percent UPL, or some other UPL is not adequately explained. 

The commenter stated the EPA merely states in conclusory fashion that the 99 percent level 

provides “reasonable assurance that the limit can be met all times” by a best performing source, 

without any analysis or explanation of why a different level of confidence would not provide 

such “reasonable assurance.” UPL Memo at 10. The commenter stated the EPA fails to reconcile 

its choice of a confidence level that “can be met all times” with the statutory language, which 

requires that EPA use an “average;” thus, the EPA’s choice of this particular UPL, which then 

determines the outcome of its floor analysis, is arbitrary. The commenter stated the EPA’s reason 

for deciding not to be more conservative in standard setting for air toxics with significant adverse 

public health effects should be adequately justified in the record; and yet, it is not.

Response 8: While the UPL can be calculated at different confidence levels, the EPA selected 

the 99 percent level in order to provide reasonable assurance that the limit can be met at all times 

by a source with emissions at the average level achieved by the best performing source or 

sources (see Docket Item No. EPA-HQ-OAR-2013-0290-0217).

In the context of development of MACT floors, the UPL is a value, calculated from a dataset, 

which identifies the average emissions level that a source or group of sources is meeting and 

would be expected to meet a specified percent of the time that the source is operating. That 

percent of time is based on the confidence level used in the UPL equation, as explained in more 

detail below. For a single best controlled emission source that serves as the basis for a new 

source MACT floor, the 99 percent UPL is the emissions level that the source would be 

predicted to be below during 99 out of 100 performance tests, including emissions tests 

conducted in the past, present, and future, based on the short term stack test data available for 

that source. It is important to note that the UPL does not represent the worst emissions 

performance of the best performing units at any time, but rather the average level expected to 

have been achieved over time, as the first element of the UPL equation is the average of the 

short-term emissions test data from the best performing units. In other words, the 99 percent 

UPL is the level of emissions that we are 99 percent confident is achieved by the average source 

represented in a dataset over a long-term period based on its previous, measured performance 

history as reflected in short term stack test data.
38

7.3 Emission Limit

Comment 1: Commenter 0247 challenged the proposed D/F emissions standards for new and 

existing wall tile kilns. EPA proposed D/F emissions limits for existing and new wall tile kilns of 

0.16 ng/dscm and 0.160.23 ng/dscm, respectively, each corrected to 7 percent oxygen.8 EPA’s 

research and calculations showed the correct emissions rate in each scenario to be 0.17 ng/dscm.9

Table 6 correctly reflects EPA’s research and calculations, identifying the correct emissions rate 

of 0.17 ng/dscm.10 Commenter 0247 stated that EPA must correct the D/F standard for new and 

existing kilns to 0.17 ng/dscm in Table 1. The commenter argued that a failure to do so would be 

arbitrary and capricious.

Response 1: The EPA agrees with the commenter that the D/F emission limits for wall tile roller 

kilns in Table 1 to subpart KKKKK were incorrect. In response to another comment from this 

and other commenters, we have changed the format of the D/F emission limits in Table 1 from 

nanograms per dry standard cubic meter (ng/dscm) to nanograms per megagram (ng/Mg) of fired 

product.

Comment 2: Commenter 0247 challenged the proposed Hg standards for new and existing wall 

tile kilns. EPA inaccurately proposed Hg emissions limits for existing and new wall tile kilns of 

6.7 E-05 kg/Mg (1.3 E-04 lb/ton) and 1.9 E-05 kg/Mg (3.1 E-06 lb/ton) of fired product.11 These 

values are inconsistent with the 2.0 E-4 kg/Mg proposed emission limit for new and existing wall 

tile kilns developed by EPA and presented in the EPA docket.12 Table 6 correctly reflects the 

emissions limitations in the docket for existing and new wall tile kilns.13 Commenter 0247 stated 

that Table 1 must be corrected to reflect the emission standards developed by EPA and provided 

in the docket. The commenter argued that a failure to do so would be arbitrary and capricious.

Response 2: The EPA agrees with the commenter that the Hg emission limits for wall tile roller 

kilns in Table 1 to subpart KKKKK were incorrect. Rounding up to the next decimal results in a 

limit of 2.1E-04 lb/ton of fired product for wall tile roller kilns.

In our review of Table 1 values, we discovered that Table 1 also contains errors for wall tile PM

emission limits, although Table 6 had the correct values. Under Item 3.a, the PM emission limit

for existing wall tile roller kilns was 0.099 kg/Mg (0.20 lb/ton), and it should have been 0.10 

kg/Mg (0.20 lb/ton). Under Item 13.a, the PM emission limit for new wall tile roller kilns was

0.15 kg/Mg (0.27 lb/ton), and it should have been 0.10 kg/Mg (0.20 lb/ton). Since proposal, we 

have examined the PM test data more closely and found that a number of the EPA Method 5 test 

runs had probe or filter temperatures outside of the range of acceptable values. EPA Method 5 

specifies that the temperature should be maintained at 248 ± 25 degrees Fahrenheit (°F) (i.e., 

between 223 and 273 °F). Test runs with temperatures outside that range were removed from the 

 8 79 FR 75704 (Dec. 18, 2014)(proposed to be codified as Table 1, rows 3c. and 13c. of 40 CFR 63, subpart 

KKKKK)

9 Docket Item No. EPA-HQ-OAR-2013-0226, Maximum Achievable Control Technology (MACT) Floor Analysis 

for Clay Ceramics, at Tables 2 and 3, pages 12 and 13 (Nov. 6, 2014). 10 79 FR 75709 (Dec. 18, 2014)(proposed to be codified as Table 6 of 40 CFR 63, subpart KKKKK) 11 79 FR 75704 (Dec. 18, 2014)(proposed to be codified as Table 1, rows 3b. and 13b. of 40 CFR 63, subpart 

KKKKK).

12 Docket Item No. 226, at Tables 2 and 3, pages 12 and 13 (Nov. 6, 2014). 13 79 FR 75709 (Dec. 18, 2014)(proposed to be codified as Table 6 of 40 CFR 63, subpart KKKKK).
39

data set, including test runs from the wall tile roller kilns. As a result, the PM MACT floor for 

wall tile roller kilns was recalculated, resulting in a revised PM limit of 0.37 lb/ton of fired 

product for existing and new wall tile roller kilns. 

Comment 3: Commenter 0247 argued that EPA has no legal authority to promulgate a D/F

standard because there is no certainty TCDD of biogenic origin is a listed HAP. The commenter 

stated that legislative history of the CAA and EPA guidance show the TCDD listing was 

intended to apply to only TCDD of anthropogenic origin. Congress stated “[T]here are hundreds 

of air toxics of concern [including] . . . and dioxin (a product of combustion whenever there is 

chlorine in the fuel.)”. S. REP. I 01-228 at Ill. The commenter stated that the phrase “[D]ioxin (a 

product of combustion ... )” is an unmistakable reference to D/F emissions of anthropogenic 

origin. The commenter also noted that the pipeline-quality natural gas used exclusively by these 

sources does not contain Cl2.

The commenter stated that Congress never intended biogenic D/F, including TCDD, to be a HAP 

subject to NESHAP regulation. The commenter argued that D/F emissions from the ceramic tile 

manufacturing industry, if they exist, are biogenic, not anthropogenic, and tightly encapsulated in 

a ball clay matrix. There is no evidence in the docket that establishes it is of non-anthropogenic 

origin. The commenter argued the D/F emissions do not have the D/F congener profile of new 

D/F created as a product of combustion. When Congress intended in the CAA to regulate 

biogenic compounds as hazardous air pollutants, the commenter noted that Congress explicitly 

granted EPA the authority to do so (e.g., regulation the emissions of “naturally-occurring”

radioactive materials as a HAP, S. REP. 95-564 at 142). According to the commenter, the fact 

that Congress chose not to refer to naturally-occurring or biogenic D/F is a strong indication, 

coupled with the legislative history that Congress chose not to regulate the emission of biogenic 

encapsulated D/F. EPA’s “Locating and Estimating Air Emissions From Sources of Dioxins and 

Furans” (United States Environmental Protection Agency, Office of Air and Radiation, EPA454/R-97-003, May 1997) makes it clear that the section 112(b) listing of TCDD is strictly 

limited to D/F of anthropogenic origin: “[chlorinated dibenzo-p-dioxins] and [chlorinated 

dibenzofurans] .... are formed as unwanted byproducts of certain chemical processes during the 

manufacture of chlorinated intermediation and in the combustion of chlorinated materials..” The 

commenter noted that although the EPA listed several examples of industries that emit D/F, they 

did not list a ceramics manufacturing operation in this guidance document. The commenter noted 

that when this document was written in 1997, the discovery of biogenic dioxin in ball clay was 

known to EPA.

Response 3: The EPA disagrees with the commenter that EPA has no legal authority to 

promulgate a D/F standard because biogenic D/F is not a HAP. In the congressional statement 

cited by the commenter, Congress never intended to make the distinction between anthropogenic 

and biogenic D/F when it stated that “dioxin [is]...a product of combustion whenever there is 

chlorine in the fuel.” Congress was simply stating the most common mechanism by which dioxin 

is created. There are many mechanisms by which some HAP are created--some naturally, some 

artificially through the manufacturing process. There is no basis for concluding that Congress 

intended for EPA to regulate HAP created by one mechanism and not another.

Comment 4: Commenter 0247 contended that EPA’s proposal to regulate congeners raised 

constitutional concerns by creating new law. The commenter noted that dioxin is not on the CAA 
40

section 112(b)(l) HAP list and the EPA proposal would regulate sixteen congeners as if they 

were TCDD, using toxicity equivalency factors (see 79 FR 75709 (Dec. 18, 2014)(proposed to 

be codified as Table 5 of 40 CFR 63, Subpart KKKKK). The ability to mathematically compare 

the toxicity of each of the sixteen congeners to one another and to TCDD is interesting and may 

be useful in other public health contexts, but it does not overcome the statutory limitation that 

EPA is permitted to regulate only compounds listed by Congress as HAP in CAA section 

112(b)(1).

The commenter stated there are constitutional and statutory limitations to EPA’s authority and 

EPA has no authority to rewrite CAA section 112(b)(1). Congress specifically provided CAA 

section 112(b)(2) and (3) in the event EPA thought CAA section 112(b)(1) list needed amending. 

EPA can petition Congress to make such changes, and Congress will decide whether or not to 

rewrite this part of the law. Commenter 0247 argued that EPA’s proposal, which attempts to 

bypass the law by regulating possible emissions of the 16 D/F congeners as if they are TCDD, is 

arbitrary and capricious.

Commenter 0247 also stated that EPA did not address in this rulemaking their authority to 

regulate emissions of these 16 congeners within the HAP category of polycyclic organic matter 

(POM) and therefore, the EPA is barred from doing so in response to these public comments. 

The commenter argued that none of the 16 D/F congeners meets EPA’s definition of POM. 

EPA’s website defines POM as “organic structures having two or more fused aromatic rings that 

have a boiling point greater than or equal to 212 degrees F (100 degrees C).” See Polycyclic 

Organic Matter (POM), United States Environmental Protection Agency, 

www.epa.gov/ttnatw0l/hlthef/polycycl.html. EPA’s guidance entitled Locating and Estimating 

Air Emissions from Sources of Polycyclic Organic Matter (p. 3-1, United States Environmental 

Protection Agency, Office of Air Quality Planning and Standards, EPA-454/R-98-014, July 

1998) and EPA guidance defines POM as: “... a broad class of compounds which generally 

includes all organic structures having two or more fused aromatic rings (i.e., rings which share a 

common border).” Biogenic D/F, including non-TCDD, in ball clay does not have two or more 

fused aromatic rings. The aromatic rings are connected by oxygen atoms without a common 

border. Since biogenic dioxin falls outside EPA’s definition of POM, the proposed D/F standard 

that includes these sixteen congeners is arbitrary and capricious.

Response 4: The EPA disagrees with the commenter that the EPA is not authorized to regulate 

dioxin congeners beyond 2,3,7,8-TCDD. While 2,3,7,8 TCDD is one of the HAP listed in section 

112, all dioxin congeners are considered to be POM (which is listed in CAA section 112(b)(1)) 

and, as such, the EPA has the authority to regulate these compounds under section 112. The 

commenter cites two references in his argument that dioxin congeners are not POM:

• Polycyclic Organic Matter (POM), United States Environmental Protection Agency, 

www.epa.gov/ttnatw0l/hlthef/polycycl.html; and

• Locating and Estimating Air Emissions from Sources of Polycyclic Organic Matter 

(p. 3-1, United States Environmental Protection Agency, Office of Air Quality Planning 

and Standards, EPA-454/R-98-014, July 1998).
41

The first reference states that “[e]ight major categories of compounds have been defined by the 

EPA to constitute the class known as POM,” and cites the second reference--the Locating and 

Estimating (L&E) document for POM sources--for the list of categories. That list of categories 

(provided on p. 3-2 of the L&E document) includes polyhalo compounds, and the L&E states 

that “some polyhalo compounds, such as polychlorinated dibenzo-p-dioxins (PCDDs) and 

polychlorinated dibenzofurans (PCDFs), may be considered as POM although they do not have 

two or more fused aromatic rings.” Therefore, according to the commenter’s own references, the 

EPA is authorized to regulate dioxin congeners beyond 2,3,7,8-TCDD.

Further, the EPA disagrees that it was required to explain the basis for its authority to set 

standards for dioxin congeners in the proposed rule preamble. Such authority has already been 

recognized previously in many other EPA rules (e.g., Boiler MACT, Hazardous Waste

Combustors, Large/Small Municipal Waste Combustors, Commercial and Institutional Solid 

Waste Incinerators, HMIWI, Other Solid Waste Incinerators, and Sewage Sludge Incinerators). 

The commenter has raised this issue in his comments, and the EPA has provided the response 

above. This is fully consistent with the procedural provisions of CAA section 307(d).

Comment 5: Commenter 0247 argued that EPA’s proposal regulates Hg emissions twice: on 

their own and as part of PM as a surrogate for HAP metals (79 FR 75651 (col. 3), Dec. 18, 2014; 

proposed to be codified at 40 CFR 63.8555(a), incorporating Table 1, and 40 CFR 

63.8595(f)(1)). This problem arises from EPA’s proposed definition of PM, which includes Hg

(see 79 FR 75682 (col. 3), Dec. 18, 2014; proposed to be codified as a portion of 40 CFR 

63.8665). The commenter presumed that EPA intended to regulate Hg emissions once. The 

commenter stated that double regulation of a pollutant in the same NESHAP is arbitrary and 

capricious, and unlawful. The commenter asserted the EPA must re-propose the proposed 

NESHAP to provide the public the opportunity to provide public comment on the option that 

EPA chooses to correct this double regulation.

Response 5: The EPA agrees with the commenter that Hg should not have been included in the 

definition of PM, because PM is being regulated as a surrogate for non-Hg metals. We have

revised the definition of PM for the final rule to remove mention of Hg. Re-proposal is 

unnecessary, because commenters were fully able to provide comment on this issue. Further, the 

mass of Hg compared to the mass of filterable PM is very small, so the removal of Hg from the 

definition of PM will make essentially no difference in the calculation of filterable PM.

7.3.1 Manipulation of Data for MACT Floor

Comment 1: Commenter 0247 challenged the proposed floor tile kiln D/F MACT floor pool and 

resulting proposed D/F standards. The commenter argued that EPA’s proposed approach to 

establishing MACT floor pools in circumstances where common stack emissions are involved is 

internally inconsistent and inconsistent with EPA NESHAP precedent. For kilns, EPA divided 

common stack emissions equally among all kilns exhausting to that stack and ranked each kiln’s 

“emissions” separately for MACT floor pool purposes. By contrast, for glaze lines, EPA 

included the common stack emission factor as a single data point for MACT floor pool purposes, 

irrespective of the number of glaze lines exhausting to that common stack. The commenter 

contended that EPA’s treatment of the glaze lines is consistent with past EPA precedent; while 

its treatment of the kilns is not. EPA offered no explanation for this inconsistent treatment of 
42

kilns. The commenter stated that there is no distinction to be made and thus the treatment of the 

kilns is arbitrary and capricious, and must be corrected.

The commenter stated EPA’s approach to kilns skews the MACT floor pool and the proposed 

emissions standard for each HAP in two ways. First, for every kiln associated with a common 

stack included in a MACT floor pool after the first one confirmed by EPA precedent, at least one 

kiln that would otherwise have ranked high enough to be included in that pool has been 

excluded. As a result, the proposed kiln MACT floor pools lack the top five performing sources, 

which violates CAA section 112(d)(3)(B). In addition, by including the same emission result 

more than once in a MACT floor, the variability within a MACT floor pool is artificially and 

unlawfully narrowed. This distorts the statistical variability adjustment of the MACT floor data 

set required by the NACWA Court that a different statistical template (skewed, lognormal or 

normal) driven by the narrowed data set may add to the inaccurate calculation of the relevant 

emission standard.

Specifically, the commenter stated that EPA used the Oklahoma kiln’s common stack test result 

three times in the proposed floor tile kiln D/F MACT floor. Kilns 60, 61 and 62 are ranked 

second, third and fourth, respectively, in this pool. Commenter 0247 challenged the inclusion of 

three separate kilns in this MACT floor when in fact there was only one test result from the 

common stack. For these reasons, the commenter proposed the more logically correct and 

historically consistent method of counting the Oklahoma test as a single data point. When this is 

done, kiln 77, which was the sixth-ranked in this floor development, would be added to this 

MACT floor pool. There would be four values in this revised MACT floor pool.

Commenter 0247 argued that EPA’s proposed UPL-based D/F standard of 4.6 ng/dscm is 

arbitrary and capricious because it is oxygen-corrected and based on the inclusion of kilns 60, 61 

and 62 in the D/F MACT floor pool. Using EPA’s data, the commenter calculated the UPLbased D/F standard to be 6.41 ng/dscm, when the proper four kiln MACT floor pool is used.

The removal of 7 percent oxygen correction results in a calculated equivalent to the 4.6 ng/dscm 

UPL-based D/F standard of 0.68 ng/dscm at standard conditions of temperature and pressure. 

The commenter stated that the oxygen correction is inappropriate and the 0.68 ng/dscm limit is 

arbitrary and capricious because it is based on inclusion of kilns 60, 61 and 62 in the D/F MACT 

floor pool. The commenter proposed a UPL-based D/F standard of 2.68 ng/dscm at standard 

conditions of temperature and pressure, exclusive of oxygen correction to 7 percent for the four 

kiln pool.

Response 1: For categories where a significant number of units are ducted to one outlet stack, 

the EPA designated the outlet stack as the “source” instead of each individual unit. The EPA 

used this methodology for tile glazing and the wall tile roller kiln categories. In the tile glazing 

category, several facilities have multiple glazing lines ducting to one stack. In the wall tile roller 

kiln category, there is one facility with 12 uncontrolled kilns going to one stack. For all other tile 

and sanitaryware categories where a less significant number of units ducted to the same outlet 

source, the EPA treated the units as distinct individual sources to be consistent with the

methodology used in BSCP.
43

There are several components of the UPL equation that have an effect on the final UPL value--

the average of the data in the MACT floor pool, variability of the data in the MACT floor pool, 

t-statistic, and “m” future compliance term. Adjusting any one of these can affect the values of 

the other terms and the final UPL value.

In general, the variability within the test runs for the unit affects the variability of the entire 

MACT pool. If the run-by-run data of the unit have little variability, then removing the duplicate 

kiln from the MACT floor pool will usually increase the overall variance and increase the UPL 

value. If the run-by-run data of the unit have significant variability, then removing the duplicate 

kiln from the MACT floor pool will usually decrease the overall variance and decrease the UPL 

value.

In general, treating units as distinct individual sources vs. a single source does not result in 

significant differences in the final UPL.

It should be noted that, in response to a public comment requesting different units of 

measurement for the D/F MACT floor, the EPA is now regulating D/F in units of ng/kg instead 

of ng/dscm at 7 percent O2. 

Comment 2: Commenters 0246 and 0247 challenged the use of oxygen correction in the 

development of the proposed D/F standard (see 79 FR 75704, Dec. 18, 2004; to be codified as 

Tables 1, 6 and 7). The commenters proposed instead that EPA use the raw D/F data without 

oxygen correction in developing the MACT D/F floor and setting D/F standards, arguing that 

EPA’s selection of an oxygen-corrected standard was arbitrary and capricious.

Commenters acknowledged that EPA had used emissions results “corrected to 7% oxygen” to set 

D/F emission standards in other NESHAP, but stated that the nature of the processes in the 

ceramic tile subcategory is such that they must operate at near-ambient air conditions. They 

argue this distinction is critical because the oxygen correction equation creates distortion in the 

reported results at the near-ambient oxygen concentration conditions found in the ceramic 

tile industry. The commenter stated that oxygen correction of raw data to 7 percent obscures 

identification of the best performing sources. The reported floor tile kiln exhaust gas oxygen 

concentrations, for example, range from 16.13 percent to 19.23 percent. Assuming these are the 

only two floor tile kilns in this subcategory and that they each emit D/F at the same 

concentration, then the oxygen corrections would be 2.914 and 8.323, respectively. In this 

example, Commenter 0247 noted that the kiln with the 19.23 percent oxygen concentration 

reports 7 percent oxygen-corrected results that are higher by a factor of 8.323/2.914 (roughly 

three times higher) than those for the kiln with the 16.13 percent oxygen concentration. With the 

same D/F concentration, the kiln with the 16.13 percent oxygen concentration would be deemed 

the best performing, when this kiln could actually emit more D/F on a concentration basis. 

Commenter 0247 also noted EPA’s Method 3A and the oxygen measurement equipment do not 

yield precise oxygen concentrations. At near-ambient oxygen concentrations, even a slight 

variation in oxygen concentration measurement has a material impact on oxygen-corrected 

results. The commenters argued that those impacts are not considered when EPA takes statistical 

variability of the data in the MACT floor pool into account. The assumption underlying that 
44

protocol is that the D/F MACT floor data pool are precise, when in fact they too are subject to 

statistical variability associated with, among other things, the oxygen concentration measurement 

equipment. The commenter argued that the proposed D/F standard failed to satisfy the statistical 

variability requirements stated by the NACWA Court and is therefore arbitrary and capricious.

Commenter 0247 acknowledged that oxygen correction creates a disincentive for operators to 

lower their emission concentration by introducing dilution air. However, the commenter stated 

that this approach is not possible in the ceramic tile manufacturing industry because the air flow 

is tightly controlled to assure a quality finished product. There is no incentive to introduce 

dilution air that could cause product quality problems.

Commenters 0246 and 0247 recommended that if D/F standards are included in the final rule, 

they should be based directly on raw D/F emissions data. If EPA decides to use data corrected 

for oxygen, then commenters 0246 and 0247 suggested the D/F emission limitations reflect 

oxygen correction to the maximum reported oxygen concentration for each source type (i.e., 

19.23 percent for kilns). Commenter 0247 stated that any oxygen concentration over the 

maximum measured during ICR stack testing of that source type could be defined as “excess.”

Response 2: In response to a public comment requesting different units of measurement for the 

D/F MACT floor, the EPA is now regulating D/F in units of ng/kg instead of ng/dscm at 7

percent O2. Therefore, the commenter’s argument is no longer applicable.

Comment 3: Commenter 0247 challenged the proposed floor tile kiln Hg MACT floor pool and 

resulting proposed Hg standard. EPA has used the same Oklahoma kilns stack test result twice in 

the proposed floor tile kiln Hg MACT floor pool. EPA ranked kilns 60, 61 and 62 fourth, fifth, 

and sixth, respectively, in this MACT floor. Commenter 0247 challenged the separate inclusion 

of each of these three kilns in this MACT floor, and the use of the common stack emission factor 

twice in the MACT floor pool. The commenter proposed that the MACT floor include only the 

single emissions factor from the common stack serving kilns 60, 61 and 62. Kiln 41, which was 

the seventh-ranked in this floor development process, would become a MACT floor pool 

participant with this correction.

In addition, the commenter stated that the emission result for the common stack within this 

MACT floor pool must be corrected. There is a transcription error in the May 13-14, 2010 

impinger lab data for run 2, which appears in EPA docket run-by-run spreadsheet cell AL6. A 

value of 41.1 was entered, but the laboratory reported 51.1. The commenter indicated this error 

must be corrected and the MACT floor calculations redone.

Commenter 0247 also stated that the production tonnage throughput rate for kiln 77 from the 

March 4-5, 2010 stack test in cells P17, P18, and P19 of EPA’s docket run-by-run spreadsheet 

does not reflect production tonnage rate reported in the stack testing report. The kiln run rate in 

the spreadsheet erroneously corresponds to confidentially-submitted run rate data for a press 

dryer. Inclusion of kiln 77 means there will still be five values in this revised MACT floor pool.

Commenter 0247 calculated the revised Hg UPL-based standard for this revised five-kiln pool to 

be 3.72 E-04 lb./ton. The commenter argued that EPA’s UPL of 1.3 E-4 is erroneous, arbitrary 

and capricious.
45

Response 3: The EPA is maintaining its methodology for treating multiple units ducted to one 

outlet for the floor tile roller kiln subcategory. The units will be treated as individual sources. 

The EPA has revised the production rate for kiln 77 and recalculated the emissions for that unit. 

The EPA has reranked the units and recalculated the UPLs accordingly. Please see the MACT 

floor memo for changes to the calculated UPL and final MACT floors. 

Comment 4: Commenter 0244 stated that the analyses presented in Tables A-12 through A-14 

of the November 6, 2014 memo from RTI International to EPA (Telander) titled “MACT Floor 

Analysis for Clay Ceramics,” show kilns 19 and 20 as separate sources with the exact same 

average emission rate and variance. As these two kilns exhaust through the same stack, they 

were tested simultaneously. The commenter asked EPA whether they should be treated as a 

single kiln since a single exhaust was tested. The commenter asked whether treating them as two 

distinct kilns, with identical emission rates and variability, minimizes the variability calculated 

via the UPL approach, resulting in a lower emission limit for sanitaryware kilns than would be 

the case otherwise.

Response 4: The sanitaryware tunnel kilns were treated as two distinct kilns vs. a single kiln to 

be consistent with the MACT floor methodology used in both the BSCP and floor tile categories. 

The same methodology for each sanitaryware tunnel kiln pollutant MACT floor was used, 

treating units going to the same stack as distinct kilns.

There are several components of the UPL equation that have an effect on the final UPL value--

the average of the data in the MACT floor pool, variability of the data in the MACT floor pool, 

t-statistic, and “m” future compliance term. Adjusting any one of these can affect the values of 

the other terms and the final UPL value.

In general, the variability within the test runs for the unit affects the variability of the entire 

MACT pool. If the run-by-run data of the unit have little variability, then removing the duplicate 

kiln from the MACT floor pool will usually increase the overall variance and increase the UPL 

value. If the run-by-run data of the unit have significant variability, then removing the duplicate 

kiln from the MACT floor pool will usually decrease the overall variance and decrease the UPL 

value.

For sanitaryware kilns 19 and 20, treating them as two distinct kilns vs. a single kiln does not 

result in significant differences in the final UPL for Hg, PM, or TEQ.

Comment 5: Commenters 0246 and 0247 challenged the proposed MACT PM surrogate floor 

pool and resulting PM surrogate standard for floor tile kilns. The commenters stated that EPA’s 

UPL-based existing kiln emission standard of 0.18 lb/ton and new source emission standard of 

0.027 lb/ton are arbitrary and capricious.

Specifically, commenters challenged EPA’s inclusion of PM data from kilns lacking air pollution 

control equipment. The commenters stated that controlled versus uncontrolled are two different 

scenarios and noted that the one controlled kiln in this MACT floor pool (kiln 41) has the highest 

reported PM emissions of the five kilns in the MACT pool. Kilns 77, 84, 36, and 76, which are 

all uncontrolled, are ranked 1-4. While one would expect operations with air pollution control 

equipment have lower emissions than their uncontrolled counterparts, air pollution control 
46

systems, such as DIFF systems, contribute to the higher measured PM emissions. According to 

the commenters, EPA’s documentation for this industry confirms PM emissions from sources 

controlled by an air pollution control device are greater than uncontrolled sources.

If all major sources operate with controls, the commenters asserted that imposing an emission 

limitation on existing floor tile kilns that is strongly influenced by uncontrolled sources is 

arbitrary. Further, the commenters argued, imposing an emission limitation on new floor tile 

kilns at major sources based on an uncontrolled source (kiln 77) is arbitrary and capricious. The 

commenters asserted that floor tile kilns with emission controls would be penalized because they 

are controlled.

To correct this situation, commenters 0246 and 0247 proposed an existing floor tile PM 

surrogate pool consisting of the best performing PM controlled sources (i.e., kilns 41, the single 

emission factor from the tests of the common stack (wet scrubber 1) serving kilns 59 and 60, and 

the single emission factor from the tests of the common stack (wet scrubber 2) serving kilns 60, 

61 and 62). The corrected UPL-based emission standard for this three-source existing source 

pool is 0.69 lb/ton. 

The commenters also opposed the proposed standard for new sources because the standard was 

based on data from an uncontrolled kiln (i.e., kiln 77). Since the kilns in this MACT pool have 

already installed controls and will not be able to cease operation to meet the proposed standard, 

the commenters stated the correct UPL-based new kiln emission standard should be 0.447 lb/ton, 

based on data from kiln 41. 

The commenters also challenged EPA’s inclusion of the 2003 PM data for kiln 76 in the MACT 

floor pool. The kiln throughput during that testing event was only 79 percent of design capacity, 

which is well below the 90 percent required for use in state permit compliance contexts. The 

commenters argued PM emissions data for this kiln should not be included because:

(1) operations at reduced throughput are not representative of the normal operation of a kiln; 

(2) HAP metals were not tested; and (3) EPA Method 5 was used instead of Method 29 specified 

by the ICR. The commenters contended that the reported results in the 2003 test of kiln 76 do not 

speciate metals and thus, provide no correlation between metals and PM emissions.

In addition, the commenters identified a transcription error in the production tonnage for the kiln 

77, March 4-5, 2010 stack test. They stated the error in the throughput affects the PM emissions 

pool for cells P65, P66 and P67 in the EPA’s kiln PM run-by-run spreadsheet. The commenters 

stated that EPA must use the production rate for kiln 77 during the stack test that was reported in 

the declassified confidential business information (CBI) letter dated August 6, 2010 (See EPAHQ-OAR-2013-0290-0090). Commenters 0246 and 0247 calculated the revised existing kiln PM 

UPL-based emission standard based on the five-source pool and corrected throughput for kiln 77 

to be 0.23 lb/ton. 

Response 5: The EPA cannot exclude kilns lacking air pollution control equipment from the 

MACT floor calculation. Cement Kiln Recycling Coal v. EPA, 255 F.3d 855, 866 (D.C. Cir. 

2001); Sierra Club v. EPA, 479 F.3d 875, 882-83 (D.C. Cir. 2007). The EPA is continuing to 
47

rank all the sources for which they have data for the floor tile roller kiln category. The EPA has 

revised the production rate for kiln 77 and recalculated the emissions for that unit.

Comment 6: Commenter 0248 stated it does not appear that the EPA excluded startups and 

shutdowns from the data used to determine the MACT floor. See 79 FR 75626. The commenter 

stated by including such data in its floor analysis, EPA inflated the proposed limits substantially 

(especially in light of the variability adjustment). The commenter stated that inflation is wholly 

unjustified if the limits do not apply during startup and shutdown; startup and shutdown 

emissions do not reflect the sources’ actual emissions during other operations.

Response 6: The EPA does not agree with the commenter’s statement that EPA included 

startups and shutdowns from the data used to determine the MACT floor. The EPA does not 

have any data during startup or shutdown periods to exclude from the data set. 

7.3.2 3xRDL

Comment 1: Commenter 0247 argued that EPA’s proposed Hg standards for existing and new 

floor tile glaze lines with glaze spray operations, new floor tile spray dryers, tile dryers and wall 

tile spray dryers fail to satisfy statistical confidence requirements. Commenter 0247 accepted 

EPA’s approach of comparing the appropriate 3xRDL value to the calculated UPL value for each 

pollutant and subcategory and selecting the larger value as the MACT floor emission limit. 

However, the commenter challenged the three-times multiplier. Absent statistical conditions not 

present here, NESHAP UPL-based emission standards are required by EPA precedent to be set at 

the 99 percent statistical confidence level (see Approach for Applying Upper Prediction Limit to 

Limited Datasets, EPA docket EPA-HQ-OAR-2010-0895, at 2-5 (Sept. 3, 2014)). The statistical 

confidence level for 3xRDL is only 85-90 percent according to EPA: “Relative pollutant 

measurement imprecision decreases to a consistent 10 to 15 percent for values measured at a 

level about three times the method detection limit (ASME, 2001).” [Id.] Elsewhere in this 

reference source, EPA suggests that the imprecision associated with the RDL is 10-20 percent. 

[Id. at page 11] Therefore, 3xRDL-based emission limits are at least 10 and as much as 15-20 

times statistically less achievable than UPL-based emissions limits. The commenter argued that 

the choice of the three-times multiplier fails to correctly account for statistical variability as 

required by National Association of Clean Water Agencies, et al. v. United States Environmental 

Protection Agency, 734 F.3d 1115 (D.C. Cir. 2013) (NACWA), and is arbitrary.

Commenter 0247 stated that EPA must correct this inconsistency by increasing the RDL 

multiplier so it is at the 99 percent statistical confidence level. An 8x multiplier may be 

supportable in its statistical comparability to the UPL. With that adjustment, the commenter 

would support EPA’s approach to setting the proposed Hg emission limit for each of the 

referenced units at the greater of the UPL and the revised, higher multiplier of the RDL.

Response 1: The EPA disagrees with the commenter, as he appears to mix two separate issues –

the confidence level necessary to determine presence or absence of a pollutant and the precision 

necessary for an accurate instrument measurement. In simple terms, the method detection level 

(MDL), which is comprised by multiplying the t-test value for seven samples at a confidence 

level of 99 percent (about 3) by the standard deviation obtained from seven replicate analyses, is 

the value above which one can say that the pollutant is present. Below the MDL, one can say the 

pollutant is absent. For MACT standard purposes, the MDLs from the best-performing sources 
48

are averaged together to provide the RDL. Following that the RDL is the average of the best 

performer’s MDLs, the RDL is about 3 times the standard deviation of the replicate analyses. 

With respect to instrument measurement precision, the EPA strives to make MACT standards 

consistent with measurement precision from new source performance standard (NSPS) and other 

MACT standards, as estimated by the American Society of Mechanical Engineer’s (ASME’s)

ReMAP study. We find that multiplying the RDL value by three (3xRDL), or 9 times the 

standard deviation of the replicate analyses, yields such a consistent value, i.e., one that is within 

10 to 20 percent of the relative standard deviation of the true measurement. This is why the limits 

are compared with the 3xRDL value.

With regard to a stricter measurement precision, the EPA finds the commenters suggestion to be 

too stringent. The Commenter suggests using 8 times the RDL (or 24 times the standard 

deviation of the replicate analyses) as the value to account for measurement precision; such a 

value is 2.4 times larger than Lindstrom suggests as a conventional assumption for measured 

quantities14 and 2.7 times larger than what the EPA uses. No changes to our methodology, or 

confidence intervals and measurement precision levels will occur

Comment 2: Commenter 0248 stated for source datasets that contained below detection limit 

(BDL) or detection level limited (DLL) data, after the subcategory UPL is calculated, the EPA 

compares the results to “the 3xRDL value of the relevant performance test method(s).” MACT 

Floor Memo - Brick at 9; see also MACT Floor Memo - Clay Ceramics at 11. The commenter 

stated after a conversion step, the 3xRDL is compared to the calculated UPL; as the EPA 

explains:

“If the calculated UPL value was less than the 3xRDL value, the 3xRDL value was used as the 

basis for the standard because the 3xRDL value provides the lowest emission rate that can be 

measured using the performance test method while maintaining a relative method precision on 

the order of 10 to 20 percent of the measured value. If the UPL value was equal to or greater than 

the 3xRDL value, then the UPL value was used as the basis for the standard.” MACT Floor 

Memo - Brick at 10; see also MACT Floor Memo - Clay Ceramics at 11.

Commenter 0248 stated the following standards are based on the 3xRDL value rather than the 

UPL:

• New brick tunnel kilns (for non-Hg HAP only)

• Existing clay ceramics floor tile press dryers

• Existing clay ceramics tile glaze lines (for Hg only)

• New clay ceramics floor tile press dryers

• New clay ceramics floor tile spray dryers

• New clay ceramics wall tile spray dryers

• New clay ceramics tile glaze lines for Hg

 14 See Limits for Qualitative Detection and Quantitative Determination, <http://nvlpubs.nist.gov/nistpubs/sp958-

lide/164-166.pdf>.
49

Commenter 0248 stated the EPA did not “demonstrate with substantial evidence” that a 3xRDL 

value represents the level achieved in practice by the best performing source or sources, as is 

required by CAA section 112(d)(3). Ne. Md., 358 F.3d at 954. The commenter stated the record 

does not show that actual emissions of units reporting emissions below the detection limit are 

triple the detection limit. The commenter stated the RDL itself has nothing to do with the 

emission level achieved by a source; rather, according to the EPA, it is just the average of the 

method detection levels that were used by all the sources the EPA considered in its floor 

calculations for existing sources. EPA, Data and Procedure for Handling Below Detection Level 

Data in Analyzing Various Pollutant Emissions Databases for MACT and RTR Emissions Limits 

1 (Dec. 13, 2011), EPA-HQ-OAR-2013-0291-0133. The commenter stated method detection 

levels are, themselves, simply the levels at which the laboratories that evaluated emission test 

results for the relevant sources could provide non-zero readings; none of the method detection 

levels EPA considered is in any way an estimate of any source’s performance, let alone the 

performance of the best performing source or sources; nor does the average of those method 

detection levels purport to be an estimate of any source’s performance. The commenter stated 

therefore, a number equal to three times the RDL is not an estimate of the single best source’s 

emission level and cannot possibly satisfy CAA section 112(d)(3)’s floor requirements.

Response 2: The purpose of the 3xRDL value is to confirm that a MACT floor value will be at a 

measureable value. UPLs developed from test data with BDL and DLL runs have a level of 

measureable uncertainty. If a calculated UPL is below the 3xRDL, then that means setting the 

MACT floor limit at the UPL would be setting the standard at a potentially unmeasurable value. 

The EPA used the data from the sources in each MACT floor pool to convert the standard 

3xRDL value (provided in Westlin-Merrill memo and found in the proposal docket at EPA-HQOAR-2013-0291-0133) into the units of measure of each UPL in order to be comparable. As 

such, the 3xRDL values are related to the sources in the MACT floor pools.
50

8.0 Health-Based Standards

8.1 Cumulative Effects

The public comments on cumulative effects can be found in section VI.C of the preamble to the 

Clay Ceramics final rule.

8.2 General Support

Comment 1: Three commenters (0244, 0246, and 0247) supported the proposed acid gas healthbased standard for clay ceramics manufacturing.

Commenters 0246 and 0247 supported the proposal to establish HF and HCl emission limitations 

under the proposed HCl-equivalent limit15 under the authority of CAA section 112(d)(4). EPA 

has exercised this authority in other NESHAP contexts and judicial precedent supports its 

exercise here. EPA considered the correct prerequisites, used well-established, health risk-based 

thresholds, and met the ample margin of safety requirement of CAA section 112(d)(4) in 

proposing an emission standard that assures no adverse health effects.

Commenter 0247 stated that CAA section 112(d)(4) provides clear authority to EPA to set 

health-based emission standards. In the 1990 Senate Report discussing Section 112(d)(4), 

Congress wrote: “To avoid expenditures by regulated entities that secure no public health or 

environmental benefit, the Administrator is given discretionary authority to consider the 

evidence for a health threshold higher than MACT at the time the standard is under review ..... 

But where health thresholds are well established, ..., and the pollutant presents no risk of other 

adverse health effects, the Administrator may use the threshold with an ample margin of safety 

(and not considering cost) to set emissions limitations for sources in the category or subcategory. 

Employing a health threshold or safety level rather than the MACT criteria to set standards shall 

not result in adverse environmental effects which would otherwise be reduced or eliminated.” S. 

Rep. No. 228 (1990).

Commenter 0247 also stated that the proposed HCl-equivalent standard is based on considerable 

data and well-established health-based thresholds (79 FR 75660 (cols. 1 and 2)). The proposed 

HCl-equivalent standard will not result in adverse environmental effects that would otherwise be 

reduced or eliminated by the CAA section 112(d)(3) NESHAP approach. There will be no 

observable adverse effects from the proposed health-based standard. There are no proposed 

exclusions from compliance. EPA considered ecosystem benefits (79 FR 75660 (col. 3)) and 

cumulative effects (79 FR 75661 (col. 1)).

Response 1: The EPA appreciates the commenters’ support for the proposed health-based 

standard for acid gases.

 15 79 FR 75661 (cols. 2-3)-75663 (col. 1) (Dec. 18, 2014)(proposed to be codified as Tables 1, 6 and 7 of 40 CFR 

63.8555(a)).
51

9.0 Work Practice Standards

Comment 1: Commenter 0248 asserted that the work practice standards that EPA proposed to 

set for startup and shutdown period emissions for all clay ceramics plants, and for all emissions 

from clay ceramics sanitaryware shuttle kilns do not satisfy the CAA’s requirements. The 

commenter’s rationale for their objection to the startup and shutdown period emissions is 

summarized in section 10.0 of this document, “Startup and Shutdown.” 

Commenter 0248 noted that section 112(h) of the CAA allows EPA to set a work practice 

standard for a category or subcategory of industrial sources, only if it is “not feasible ... to 

prescribe or enforce an emission standard for control of a hazardous air pollutant or pollutants.” 

Congress defines in the statute “not feasible to prescribe or enforce an emission standard” as 

meaning that:

(A) a hazardous air pollutant or pollutants cannot be emitted through a conveyance 

designed and constructed to emit or capture such pollutant or that any requirement for, or 

use of, such a conveyance would be inconsistent with any Federal, State or local law, or

(B) the application of measurement methodology to a particular class of sources is not 

practicable due to technological and economic limitations.

Id. CAA section 112(h)(2). If this requirement is met, the work practice standard nonetheless 

must be “consistent with the provisions of subsection [112](d).” Id. CAA section 112(h)(1).

Response 1: The EPA’s responses to Commenter 0248 regarding their objection to the work 

practice standards for sanitaryware shuttle kilns are provided later in this section. The EPA’s 

response to Commenter 0248 regarding their objection to the work practice standard for startup 

and shutdown period emissions is provided in section 10.0 of this document, “Startup and 

Shutdown.”

Comment 2: Commenter 0248 argued that EPA’s work practice standards for clay ceramics 

sanitaryware shuttle kilns are unlawful and arbitrary and violate CAA section 7412(h) and 

7412(d). The commenter provided the following reasons in support of their statements:

1. The EPA lacked factual basis for asserting HCl breakthrough presents problems for EPA 

Methods 26 and 26A. EPA lacked any information for clay ceramics sanitaryware shuttle 

kilns about whether HCl emissions are variable and experience large spikes, and 

experience breakthrough during testing. EPA only speculated that shuttle kilns “could 

encounter a similar problem” as brick periodic kilns. (79 FR 75662). Even if 

breakthrough can occur and retesting required, that does not present a technological 

hurdle rendering the methods impracticable for the entire class of sources. It only means

that additional time and costs may have to be expended in some instances, which does not 

show that the measurement methodology is not practicable, either technologically or 

economically. EPA did not claim that such costs would be high, nor did EPA attempt to 

estimate the costs.
52

2. EPA’s assertion that additional manpower would be required does not constitute a 

technological or economic limitation and EPA did not assert that the costs of the 

additional manpower would be high and did not attempt to estimate the costs.

3. Even if EPA’s asserted reasons for the impracticability of applying conventional methods 

to HCl and HF emissions are supportable, they do not justify work practice standards for 

Hg and non-Hg HAP metals because those pollutants would be measured through PM 

testing. EPA did not say that emissions of other regulated pollutants would encounter the 

same issues. To the contrary, EPA acknowledged that different methods (i.e., EPA 

Methods 5 or 17) would be used to test for PM as a surrogate for non-Hg HAP. Work 

practice standards are only allowable where it is not feasible to prescribe or enforce “an 

emission standard” for control of “a hazardous air pollutant or pollutants.” 42 U.S.C. 

Section 7412(h)(1). Thus, EPA must make a supportable determination that an emission 

standard is infeasible for each hazardous air pollutant, which the EPA has not done. Also, 

EPA Method 320 is a practicable alternative to Methods 26 and 26A. EPA has 

recognized that FTIR does not present technological limitations (see 79 FR 75662 (“With 

FTIR, HCl breakthrough is not an issue.”)). The EPA is allowed to set work practice 

standards in lieu of numerical emissions limits only if economic limitations rendered the 

measurement of emissions truly “impracticable.” Congress required MACT-based 

emissions limits be set at least as stringent as the floors, regardless of cost. The EPA had 

not explained why Method 320 is economically infeasible for shuttle kilns. EPA did not 

compare testing costs to sales or to profits and only conducted an “informal” analysis 

based on allegedly confidential business data for which they provided no documentation 

showing economic infeasibility. 

4. The EPA noted that variability would interfere with stack testing; however, the 

commenter noted that stack testing is a snapshot of emissions at a certain period in time, 

and emissions can be variable over time. The commenter noted that the variability in 

stack testing did not prevent EPA from using stack testing as a measurement 

methodology for other sources, such as tunnel kilns. The commenter stated that EPA had 

not explain why stack testing is practicable for other sources but not for shuttle kilns. 

5. The EPA did not specify whether the work practice standards for emissions from clay 

ceramics sanitaryware shuttle kilns apply to Cl2 emissions. The commenter asserted that 

it is illegal for EPA to fail to set a standard for a hazardous air pollutant emitted by a 

source. 42 U.S.C. Section 7412(d)(2)-(3); Nat’l Lime Ass’n, 233 F.3d at 634.

6. The proposed work practice standards do not reflect measures that yield the maximum 

achievable degree of reduction in these pollutants (i.e., pollutant reductions consistent 

with the reductions that would be achieved by a numerical standard). The commenter 

argued, the proposed standards are not consistent with Section 7412(d) and violate 

Section 7412(h). The commenter noted that EPA is aware that HAP emissions are 

influenced by factors such as the content of surface coatings, body additives, and raw 

materials, and that these factors could be addressed through work practice standards. See 

67 FR 47907 (“HAP metals may emanate from trace quantities of metals found in raw 

materials [or] metallic body additives and surface coatings commonly used in the 

industry.”); id. at 47899.

The commenter also stated that the phrase “or equivalent” in the proposed work practice 

standard: “[e]ach facility would have to use natural gas or equivalent as the kiln fuel, except 
53

during periods of natural gas curtailment or supply interruption” (79 FR 75663) is ambiguous. 

The commenter recommended the EPA revise the proposed language to clarify that kilns are 

required to use natural gas or the cleanest available fuel. Also, the exclusion for “periods of 

natural gas curtailment or supply interruption” would not ensure pollutant reductions consistent 

with the reductions that would be achieved by a numerical standard, and therefore is unlawful 

and must be removed.

Response 2: The EPA disagrees with the commenter that testing of sanitaryware shuttle kilns 

using Method 26 or 26A poses no technological or economic limitation. The EPA also disagrees 

with the commenter that we did not assert that the costs of manpower to conduct the tests would 

be high or that we did not attempt to estimate such costs (see 79 FR 75662, col. 2). As noted in 

the preamble to the proposed rule, conducting a shuttle kiln test on even the shortest cycle time 

would require a test crew to be on site for at least 24 hours and would require the test team to 

have at least a dozen or more sampling train set-ups or additional manpower on site to recover 

samples and turn-around sampling trains for subsequent use during the test. It is estimated that 

the test of a single shuttle kiln firing cycle with analysis would cost $20,000 or more (2009 

dollars). Due to the variations in emissions during firing cycles and variations in emissions 

across the tests, sampling a single kiln cycle might not be adequate for characterizing shuttle kiln 

emissions. To collect three test runs of data, two additional cycles would need to be tested, 

bringing the cost to $60,000 or more (2009 dollars) to test a single shuttle kiln. Furthermore, 

because shuttle kilns are used to fire a wide variety of products that may have significantly 

different time-temperature profiles, it may be necessary to test the same kiln multiple times to 

characterize emissions from different types of products. Furthermore, the sanitaryware facilities 

covered under this proposed Clay Ceramics manufacturing rule have three or more shuttle kilns 

each, requiring additional tests at each facility, potentially resulting in test costs of $180,000 or 

more per facility. Add to that the possibility that such lengthy testing might have to be redone in 

the event of HCl breakthrough, and it is clear that Method 26/26A testing is not a practical 

method for testing acid gas emissions from shuttle kilns. Consequently, the rest of our analysis 

focused on FTIR as the only practical alternative left to review.

The same argument about cost could also be made for FTIR, since the cost for testing by FTIR is 

estimated to be $49,750 (2009 dollars) for a single 50-hour kiln cycle (the average cycle time for 

a BSCP periodic kiln). Assuming a 50 percent reduction in cost for an average 25-hour 

sanitaryware shuttle kiln cycle, the cost to test one cycle would still be substantial (nearly

$25,000 (2009 dollars)). If it were determined that the variations in emissions from cycle to cycle 

were significant, it might be necessary to test each kiln for two or more cycles in order to 

develop a representative emission rate. Testing for a second cycle would double the testing cost 

to almost $50,000 and testing for a third cycle would triple the cost to almost $75,000 (2009 

dollars). In addition to these costs, additional costs would be incurred for testing the kilns for PM 

emissions, which would have to be tested using a manual test method, such as EPA Method 5/17,

multiple times over very lengthy periods. If additional shuttle kilns needed to be tested at each 

facility, the costs would be even higher. This amount of testing and retesting for such lengthy 

periods poses substantial technological and economic limitations. Therefore, we clearly believe 

that the section 112(h) criteria for setting work practice standards have been met.
54

While no formal cost-to-sales analysis was conducted for sanitaryware shuttle kilns like the one 

conducted for BSCP periodic kilns, a similar informal analysis was performed using the sales 

and production data provided in the 2008 EPA survey responses. These data were claimed as 

CBI by the respondent and, therefore, were not in the public record, as the commenter noted. 

Regardless, based on this analysis, a similar conclusion (that testing is not economically feasible) 

can be reached. Because the test costs are similar and shuttle kilns represent a small share of total 

sanitaryware production and revenues, the EPA has concluded that it would not be economically 

feasible to require testing for shuttle kilns.

The EPA disagrees with the commenter’s contention that the emissions variability for shuttle

kilns is comparable to that for tunnel kilns. As stated above, shuttle kilns have variations during 

firing cycles and variations in emissions across tests. These variations are substantially greater 

than those observed for continuously operating tunnel kilns. In addition, unlike tunnel kilns, 

shuttle kilns are used to fire a wide variety of ceramic products that may have significantly 

different time-temperature profiles, which also increases variability for a particular shuttle kiln.

In response to the commenter’s question, the work practice standards for emissions from 

sanitaryware shuttle kilns do not apply to Cl2 emissions. There are no valid Cl2 emissions data 

for clay ceramics facilities.

As provided under CAA section 112(h)(1), a work practice standard “reflects the best 

technological system of continuous emission reduction which (taking into consideration the cost 

of achieving such emissions reductions, and any non-air quality health and environmental impact 

and energy requirements) the Administrator determines has been adequately demonstrated. The

EPA disagrees with Commenter 0248 that the standards for emissions from sanitaryware shuttle 

kilns do not address emissions from those sources. As noted in the preamble (79 FR 75645-6), 

“information provided to the EPA indicates there are six operational factors that have a direct 

bearing on HAP emissions from periodic kilns (such as shuttle kilns): Temperature, firing cycle, 

product quality, automatic control, combustion control and kiln load/kiln technology.” The work 

practice standards address each of these factors to limit the emissions from sanitaryware shuttle

kilns. In addition, the work practice standards for sanitaryware shuttle kilns requires each facility 

to use natural gas or equivalent as the kiln fuel, except during periods of natural gas curtailment 

or supply interruption. The term “equivalent” is meant to refer to a fuel with equivalent 

properties, which would include emissions from fuel-burning; no clarification is needed.

With regarding to the commenter’s request for EPA to remove the provision allowing for

alternative fuel during “periods of natural gas curtailment or supply interruption,” this provision 

is essential for a workable standard, because natural gas may not always be available. To ensure 

close monitoring of such situations, the rule includes a provision requiring sources to submit a 

notification of alternative fuel use within 48 hours of the declaration of a period of natural gas 

curtailment or supply interruption that specifies the reason they are unable to use natural gas or 

equivalent fuel, including the date when the natural gas curtailment was declared or the natural

gas supply interruption began; the type of alternative fuel that they intend to use; and dates when 

the alternative fuel use is expected to begin and end. The rule also includes a provision requiring 

sources to submit a report of alternative fuel use within 10 working days after terminating the use

of the alternative fuel. The report must include the reason for using the alternative fuel, the type 
55

of alternative fuel used to fire the affected kiln, the dates that the use of the alternative fuel 

started and ended, and the amount of alternative fuel used.

Comment 3: Commenter 0244 supported the use of work practice standards for shuttle kilns. 

However, the commenter noted that their company has not developed and does not use designed 

firing time and temperature cycles for each product fired in a shuttle kiln. Any shuttle kiln batch 

will be comprised of a variety of different products being fired together, and so only one or two 

batch cycle curves are developed per kiln.

Response 3: The EPA appreciates the commenter’s support for the use of work practice 

standards for shuttle kilns and agrees with the commenter regarding the need for clarification.

The work practice standards in Table 3 have been revised for the final rule accordingly. Similar 

text has also been revised in 40 CFR 63.8640(c)(7)(i)-(ii), Table 6 and Table 7 for the final rule.
56

10.0 Startup and Shutdown

The significant public comments on startup and shutdown can be found in section VI.D of the 

preamble to the Clay Ceramics final rule. The remaining public comment and EPA’s response is 

presented in this section.

Comment 1: Commenter 0248 stated that the EPA’s proposed work practice standards for 

periods of startup and shutdown are unlawful because the EPA is authorized to set work practice 

standards only for classes of sources, not for periods of operation. CAA sections 112(d)(1) and 

(2), read together, demonstrate that separate standards may be set only for categories or 

subcategories of sources, which must be of a different class, type, or size. The commenter stated 

that because the EPA does not claim or demonstrate that measurement is impracticable for the 

categories of brick, or for subcategories of clay ceramics kilns as a class, the proposed work 

practice standards are unlawful.

Commenter 0248 stated that the EPA’s statements in support of its proposal to implement work 

practice standards do not amount to the “determin[ation]” required by CAA section 112(h) that 

either section 112(h)(2)(A) or (2)(B) has been satisfied. The EPA does not articulate that 

measurement of emissions during startup and shutdown “is not practicable” due to technological 

or economic limitations. And, to the extent that EPA believes work practice standards are 

authorized under section 112(h)(2)(A), the EPA does not “determine[]” that a pollutant “cannot 

be emitted through a conveyance designed and constructed to emit or capture such pollutant” 

during startup shutdown periods. The absence of the requisite statutory determination under 

section 112(h)(2) by the Administrator alone renders the proposed work practice standards 

unlawful.

Commenter 0248 further stated that the EPA has not satisfied the statutory requirement that 

testing “is not practicable due to technological ... limitations,” nor would the record support such 

a claim with substantial evidence. See Ass’n of Data Processing Serv. Org. v. Bd. of Governors 

of Fed. Reserve System, 745 F.2d 677, 684 (D.C. Cir. 1984) (substantial evidence standard 

applicable to agency’s factual judgments in informal rulemaking); Ne. Md.. 358 F.3d at 954 

(applying substantial evidence standard to the EPA’s MACT floor determination); NACWA, 734 

F.3d at 1138 (same). The EPA’s conclusory statements do not constitute a determination of 

impracticability under CAA section 112(h)(2)(A), nor do they amount to substantial evidence 

that it is not practicable to apply measurement technology during startup and shutdown periods 

under CAA section 112(h)(2)(B). The commenter stated that the EPA has not considered 

whether measurement methods other than the ones the EPA is proposing could be used for 

startup and shutdown periods, and the record does not contain information about such methods. 

The EPA did not specifically address, or support with substantial evidence, why fluctuating 

conditions would make it impracticable to measure each type of hazardous air pollutant. The 

EPA must select a different method for such periods, or make and support with substantial 

evidence a determination that no such method is available. Work practice standards are permitted 

only where it is entirely “infeasible to prescribe or enforce an emission standard,” not just 

infeasible during certain periods.
57

Commenter 0248 noted that the EPA has not claimed that CEMS could not be used to measure 

emissions during startup and shutdown periods, and stated that the EPA must also consider 

whether the use of mass-based limits would be technologically feasible. Methods of estimating 

emissions during startup and shutdown, such as emission estimates based on the operating 

parameters of PM controls, could substitute for the direct monitoring of emissions.

Commenter 0248 stated that the problem the EPA identifies with using the “equivalent” emission 

limits during startup and shutdown is irrelevant to the statutory standard, which is whether use of 

measurement methodology “is not practicable due to technological and economic limitations.” 

Id. CAA section 112(h)(2)(B). The format of the emissions standard is not a “technological” or 

“economic” limitation, and has no bearing on whether there are methods that are technologically 

practicable for application to kilns during startup and shutdown. The commenter stated that, as 

the EPA recognized, the emission limits pounds per ton are appropriate and practicable for 

startup and shutdown periods. Nothing requires the EPA to provide the other “equivalent” 

emission limits, and if such limits are inappropriate for startup and shutdown periods as the EPA 

claims, then the EPA need not offer them for such periods. Further, the EPA cannot devise the 

“equivalent” limits itself (which are not required by the Act), and then point to them as a reason 

why MACT standards cannot be set for periods of startup and shutdown.

Commenter 0248 further stated that even if the EPA’s startup and shutdown work practice 

standards for plants with air pollution control devices (APCDs) are valid, concerns about those 

sources’ ability to vent exhaust through the control devices lend no support to setting work 

practice standards for sources that do not employ control devices.

Commenter 0248 stated that the EPA’s proposed work practice standards for startup and 

shutdown periods contravene CAA section 112(h)(1) because they do not reflect measures that 

yield the maximum achievable degree of reduction in these pollutants (i.e., pollutant reductions 

consistent with the reductions that would be achieved by a numerical standard) and that at a 

minimum reflect the measures adopted by the facilities with the lowest emission levels during 

startup and shutdown. The EPA does not claim the work practice standards are “consistent with 

the provisions of subsection (d) or (f)” of section 112. The EPA provides no basis for assuming 

that sources operating during startup and shutdown periods would necessarily meet the pertinent 

section 112(d) numeric limits. Under the proposed work practice standards, sources would not be 

required to engage their pollution control devices during startup and shutdown periods, and the 

recordkeeping and reporting requirements themselves are neither work practices nor means for 

reducing emissions. Even if the sources are not feeding bricks into the kiln, they will be burning 

fuel during those time periods, which will result in hazardous air pollutant emissions that might 

be higher than the numerical limits.

Commenter 0248 stated that the D.C. Circuit has specifically held that the CAA requires that 

“there must be continuous section 112-compliant standards.” Sierra Club v. EPA, 551 F.3d 1019, 

1027 (D.C. Cir. 2008). But the revised final rule includes no continuous, section 112-compliant 

work practice or other emission standard to limit the rate of emissions during startup and 

shutdown. The commenter suggested that at a minimum, the EPA could require sources to use 

natural gas or the cleanest available alternative as a fuel during periods of startup and shutdown. 

Further, the EPA needs to set limits on the time that sources spend in startup and shutdown mode 
58

to prevent the startup and shutdown provisions from being abused as a means to avoid 

compliance with emission standards.

Response 1: The EPA appreciates the support from multiple commenters for the use of work 

practice standards for periods of startup and shutdown. As discussed later in this section, the 

EPA has revised the work practice standards for periods of startup and shutdown for clay 

ceramics kilns to provide requirements for minimizing emissions that are feasible for all kilns.

The EPA disagrees with Commenter 0248 that work practice standards for periods of startup and 

shutdown are unlawful. We disagree with the commenter that the standards were set for periods 

of operation, rather than classes of sources. The standards were set for ceramic tile roller kilns 

and sanitaryware tunnel kilns, which are sources in the clay ceramics manufacturing source 

category. We also disagree with the commenter that we did not state that measurement was 

impracticable due to technological limitations. As we stated in the preamble to the proposed rule, 

“we recognize that it is not feasible to conduct emission testing during periods of startup and 

shutdown.” 79 FR 75647.

The EPA further disagrees with Commenter 0248 that EPA must also demonstrate that a 

pollutant “cannot be emitted through a conveyance designed and constructed to emit or capture 

such pollutant” during startup and shutdown periods. Section 112(h)(1) allows work practice 

standards only if pollution is not emitted through a conveyance or “the application of 

measurement methodology to a particular class of sources is not practicable. (emphasis added) 

As noted in the previous paragraph, the EPA has already demonstrated the latter.

The EPA has revised the standards for promulgation for both the BSCP and clay ceramics 

categories, based on public comments and additional information provided by the BSCP industry 

following proposal on the procedures used during startup and shutdown for BSCP tunnel kilns 

that are more representative of the best performing kilns in both categories. The EPA is confident 

that these standards will provide the maximum limitation of emissions possible during periods of 

startup and shutdown, ensuring that the Clay Ceramics Manufacturing NESHAP includes 

continuous section 112-compliant standards during all periods of operation.

Comment 2: Commenter 0250 asked that the rule language be modified in sections 63.8555 and 

63.8570(a) to include an exclusion from the numeric limit for periods of startup and shutdown. 

In support of this request for the rule language change, Commenter 0250 discussed requirements 

for the determination of an emission limit, and how the EPA had not met those requirements 

when setting an emission limit that is applied to startup and shutdown periods in the proposed 

rule. The commenter agreed with the reasons stated in the preamble that support work practice 

standards for startup and shutdown periods. However, the commenter also questioned whether 

the EPA had the data and had conducted sufficient analysis to demonstrate the achievability of 

the MACT emission limits established for normal operations during startup and shutdown 

events. Commenter 0250 stated the following concerns:

• It is not apparent from the preamble discussion of alternate standards for startup and 

shutdown periods that the EPA has actually analyzed sufficient data on emissions during 

startup and shutdown to justify the Agency’s conclusion that, “the EPA has taken into 
59

account startup and shutdown periods.” 79 FR 75626. Instead, based on the EPA’s 

statements about the timing of startup and shutdown of control equipment, as discussed 

above, it may be more that the EPA has merely assumed the preamble’s discussion to be 

correct (without need for such analysis).

• There are several reasons why adequate data often do not exist to allow EPA to conclude 

that an emission limitation established for normal operations also represents the 

performance of the best demonstrated control technology during startups and shutdowns, 

which would cause the EPA to understate emissions.

o To the extent emissions data come from required performance tests, the applicable 

regulations generally prohibit testing during startup, shutdown and malfunction 

(SSM) conditions, and further require that data not be used for compliance 

purposes if obtained during a startup, shutdown, or malfunction event.16

o To the extent the EPA evaluates emissions data collected through continuous 

monitoring, the applicable regulations often require or allow the source to exclude 

from its reporting of continuous monitoring data those data reflecting SSM 

conditions.

o Atypical pollutant concentrations and other stack conditions that may exist during 

startup and shutdown can result in the continuous monitoring system producing 

unusable data, because the pollutant concentration may be outside of the 

monitoring equipment’s span or the stack conditions may not meet monitoring 

system quality assurance/quality control (QA/QC) parameters, or the data may be 

truncated on the high end because of limitations of the monitoring equipment.17

Commenter 0250 stated that it can be unclear whether a condition that leads to excess emissions 

should be characterized as a startup or shutdown event, or a malfunction event. Without a clear 

demarcation (both in EPA regulations and in practice), the EPA may be analyzing data sets that 

exclude events that the source treated as malfunctions but the Agency would instead say should 

be included in calculating average performance as startup or shutdown conditions.

Response 2: The EPA disagrees with the commenter that we are requiring sources to meet the 

same emission limits during periods of normal operation and periods of startup and shutdown. 

As noted in Table 3 to both the BSCP Manufacturing NESHAP and the Clay Ceramics 

Manufacturing NESHAP, we have set work practice standards to apply during periods of startup 

and shutdown. As stated in the previous response, the EPA has revised these standards for 

promulgation to provide requirements for minimizing emissions that are feasible for all kilns.

Comment 3: Commenter 0250 asserted that emission limitations should not apply at all times, as 

is implied in 40 CFR 63.8570(a). The commenter noted that although the Sierra Club v. EPA

(D.C. Cir. 2008) decision recognized that different standards, including non-numerical standards, 

may (and, in some cases, must) apply during non-standard operating conditions, the Sierra Club

 16 See, for example, the NESHAP General Provisions, which state that performance tests can only be conducted 

under representative conditions and which specify that: “Operations during periods of startup, shutdown, and 

malfunction shall not constitute representative conditions for the purpose of a performance test....” 40 CFR 

63.7(e)(1); see also 40 CFR 60.8(c) (same for performance testing for NSPS).

17 Note that data from periods when a monitoring system is outside of control limits are required to be excluded 

from emission averages under the NESHAP General Provisions. See 40 CFR 63.8(c)(7)(ii).
60

decision does not prevent EPA from adopting emission standards for SSM periods that are 

different from those required during periods of normal operation. The commenter stated that the 

Sierra Club decision does not bar the EPA from using a “requirement relating to the operation or 

maintenance of a source to assure continuous emission reduction” as the emission standard for 

SSM events. See 551 F.3d at 1027. The Sierra Club decision only rejected EPA’s assertion that 

it had discretion to decide not to impose any emission standard covering SSM periods. See id. at 

1027-28, 1030 (noting that EPA was not claiming that the General Provisions SSM exemption 

was either an emission standard under CAA section 112(d) or a design, equipment, work 

practice, or operational standard under section 112(h)). The commenter stated that the majority 

opinion was that “Congress gave no indication that it intended the application of MACT 

standards to vary based on different time periods,” 551 F.3d at 1028: (1) is contradicted by other 

statements in the opinion, referenced above, that a MACT standard need not continuously apply 

a single emission limitation, (2) is dicta, because that was not the situation presented by the 

challenged regulations and argued by EPA, (3) ignores the extensive case law about technologybased limitations referenced above, and (4) does not in any event say that the CAA precludes 

EPA from adopting different emission limitations that apply during SSM events.

Commenter 0250 stated that Cement Kiln Recycling Coalition v. EPA, 255 F.3d 855 (D.C. Cir. 

2001) is the only court decision that addresses SSM issues under CAA section 112, and noted the 

decision for this case is consistent with Essex Chemical and the other NSPS cases. In Cement 

Kiln Recycling Coalition, the D.C. Circuit court decided to vacate the standards partly because of 

the Court’s concerns about EPA’s failure to exempt hazardous waste combustors from numerical 

emission limits during SSM periods, instead of “permitting sources to return to compliance by 

following the steps of a startup, shutdown, and malfunction plan filed with the Agency....” The 

Court had “similar doubts about EPA’s decision to require sources to comply with standards 

even during openings of emergency safety valves caused by events beyond the sources’ control.” 

Id. at 872. In response to that decision, EPA revised the rule to exempt facilities from the 

limitations during SSM events. See 40 CFR 68.1206(b)(1); 67 FR 6792, 6798, 6813 (February 

13, 2002).Commenter 0250 disagreed with the EPA’s statement that its treatment of excess 

emissions during SSM events was “required” in order to make the standards “consistent with” 

the D.C. Circuit’s decision in Sierra Club v. EPA, 551 F.3d 1019 (D.C. Cir. 2008), cert. denied, 

130 S. Ct. 1735 (2010). The commenter stated that the D.C. Circuit’s Sierra Club decision does 

not compel or even support EPA’s proposed SSM provisions. The commenter argued that the 

Sierra Club decision did not address what the EPA may or may not include in category-specific 

MACT standards. The commenter noted that court decisions have emphasized the need for 

standards to recognize and accommodate higher emission levels that occur at times other than 

normal operations. See, e.g., Sierra Club v. EPA, 167 F.3d 658, 665 (D.C. Cir. 1999) (Section 

112(d) standards based upon the performance of the best-performing facilities are supposed to 

represent “the emissions control that is achieved in practice” by the best performers; this means 

that the best-performing facilities will not violate the standards, and that will “only result[] if 

‘achieved in practice’ is interpreted to mean ‘achieved under the worst foreseeable 

circumstances.’”); Cement Kiln Recycling Coalition v. EPA, 255 F.3d 855 (D.C. Cir 2001) (the 

Court choosing to vacate rather than simply remand MACT standards, based in part on the 

Agency’s failure to exempt hazardous waste combustors from numerical emission limits during 

SSM periods and the Court’s “similar doubts about EPA’s decision to require sources to comply 
61

with standards even during openings of emergency safety valves caused by events beyond the 

sources’ control.” Id. at 872).

The commenter further noted the Sierra Club decision did not say that the same emission 

limitations derived for normal operations must apply during SSM events. Sierra Club does not 

preclude EPA from applying different standards during SSM events than apply during normal 

operations. In fact, the opinion acknowledges that section 302(k)’s “inclusion of [the] broad 

phrase” “any requirement relating to the operation or maintenance of a source to assure

continuous emission reduction” in the definition of “emission standard” suggests the EPA can 

establish MACT standards consistent with CAA section 112 “without necessarily continuously 

applying a single standard.” See 551 F.3d at 1027. The commenter stated their interpretation is 

also supported by the legislative history of section 302(k), which stated that “accepting that 

‘continuous’ for purposes of the definition of ‘emission standards’ under CAA section 302(k) 

does not mean unchanging” and referring to “the CAA’s requirement that some section 112 

standard apply continuously.” Moreover, the commenter noted, because it was addressing only a 

generic SSM exemption, the Sierra Club decision did not consider whether EPA, in the context 

of individual categorical standards, could determine that it is infeasible to apply the same limits, 

or any limits at all on the mass or concentration of pollutants emitted, during SSM events, or that 

it would lead to absurd results to do so.

The commenter also argued there is precedent for the EPA applying a different standard during 

SSM events. They stated that for over 30 years the EPA has not required sources to meet NSPS 

emission limitations under CAA section 111 established for normal operations during SSM 

events. See 40 CFR 60.8(c). According to the commenter, Congress enacted the “continuous 

basis” language in section 302(k) with the knowledge that EPA’s emissions standards under 

section 111 exempted SSM periods. The commenters argue there is nothing in the legislative 

history of the 1977 amendments to the CAA that suggests Congress intended to overturn that 

practice. Moreover, the commenter noted that court decisions both before and after the CAA

Amendments of 1977 have affirmed the appropriateness of including special SSM provisions in 

standards issued under section 111 despite the “continuous basis” language in the definition of 

“emission limitation.” Similarly, there is nothing in the legislative history of the CAA

Amendments of 1990 that suggests Congress meant something completely different when it used 

the same defined terms, “emission standard” and “emission limitation,” in directing EPA, in 

amendments to section 112 that establish MACT standards.

The commenter also noted the Sierra Club decision did not address whether EPA could use a 

“design, equipment, work practice or operational standard,” as authorized under CAA section 

112(h) and included in the definition of “emission limitation” and “emission standard” in CAA 

section 302(k), in lieu of a numerical emission limitation during SSM events. The EPA told the 

Court that the General Provisions SSM exemption struck down in Sierra Club was not an 

alternative standard based on the work practice standard authority (See 551 F.3d at 1028) but 

argued in that case that section 112(h) was irrelevant to its authority to exempt excess emissions 

during SSM events (see Id. at 1030 (Randolph, J. dissenting)).

Commenter 0250 stated that under CAA section 112(d)(2), MACT emission standards, including 

those that apply during SSM events, must be “achievable” with available technology, “taking 
62

into consideration the cost of achieving such emission reduction, and any non-air quality health 

and environmental impacts and energy requirements.” An emission limitation that applies during 

SSM events has not been demonstrated to be “achieved” by the best-performing 12 percent of 

units in the category under CAA section 112(d)(3), unless EPA can show that those best 

performers actually meet that emission limitation during SSM events. The commenter argued the 

EPA cannot establish “continuous section 112-compliant standards” because EPA has not 

demonstrated that the emission would comply with section 112 when applied during SSM 

events.

Commenter 0250 explained that the courts have recognized that a “technology based standard 

discards its fundamental premise when it ignores the limits inherent in technology.” NRDC v. 

EPA, 859 F.2d 156, 208 (D.C. Cir. 1988). For example, the D.C. Circuit recognized, in Portland 

Cement Ass’n v. Ruckelshaus, 486 F.2d 375, 398 (D.C. Cir. 1973), a decision reviewing 

standards under CAA section 111, that “‘start-up’ and ‘upset’ conditions due to plant or emission 

device malfunction, is an inescapable aspect of industrial life and that allowance must be made 

for such factors in the standards that are promulgated.” Id. at 399. Similarly, in Essex Chem. 

Corp. v. Ruckelshaus, 486 F.2d 427, 432 (D.C. Cir. 1973), cert. denied, 416 U.S. 969 (1974), 

another section 111 case, the D.C. Circuit held that SSM provisions are “necessary to preserve 

the reasonableness of the standards as a whole.” Id. at 433. In National Lime Ass’n v. EPA, 627 

F.2d 416 (D.C. Cir. 1980), another case reviewing emission standards promulgated under CAA 

section 111, the D.C. Circuit held that the CAA requirement that NSPS be “achievable” means 

that the standards must be capable of being met “on a regular basis,” including “under most 

adverse circumstances which can reasonably be expected to recur,” including during periods of 

SSM. 627 F.2d at 431 n.46.

Commenter 0250 also discussed analogous Clean Water Act requirements and noted that in one 

case the court held that where the EPA knew that there would be periods even with “exemplary 

use of” the identified best technology, the emissions would exceed the effluent limitations 

because of conditions “beyond the control of the permit holder,” EPA had violated the Clean 

Water Act by failing to provide an “upset provision” to address those periods. Marathon Oil Co. 

v. EPA, 564 F.2d 1253, 1273-74 (9th Cir. 1977). See also, e.g., NRDC v. EPA, 859 F.2d at 207 

(distinguishing between technology-based effluent limitations, where some provision for 

“upsets” is required, and water-quality-based effluent limitations, which are tied to achieving 

water quality standards rather than based on available technology, and, therefore, need not 

include an upset provision).

The commenter asserted that the Weyerhaeuser Co. v. Costle decision EPA cites in the preamble 

to the Proposed Rule (i.e., 590 F.2d 1011 (D.C. Cir. 1978), does not support EPA’s position. In 

that case, the court was discussing a “technology-forcing” standard and not a MACT standard

that must be based on what is demonstrated to be achievable. The commenter also notes that 

SSM events are unusual “uncontrollable acts of third parties, such as strikes, sabotage, operator 

intoxication, or insanity” that the Court was considering in the passage quoted by EPA, see id. 

Industry is not requesting that the NESHAP provide relief from numerical emission limitations 

during those unusual types of events. Moreover, most of the cited events would not constitute 

“malfunctions,” as EPA defines that term in 40 CFR 63.2 and in other policy statements, since 

they are the result of deliberate actions (e.g., deciding to continue to operate with inadequate 
63

staffing during a strike) or would constitute “careless operation” (e.g., operator intoxication). The 

commenter also pointed out that the Weyerhaeuser decision was made before NRDC v. EPA, 859 

F.2d 156 (D.C. Cir. 1988) which affirmed the need for an upset provision to address 

circumstances where compliance with effluent limitations is impossible through no fault of the 

permittee, and which endorsed Marathon Oil.

Response 3: Exemptions for startup and shutdown are inconsistent with the holding in Sierra 

Club that emissions limitations under section 112 must apply continuously. The Sierra Club

decision does not constrain our authority to prescribe unique standards or work practice 

standards during SS periods where such standards are justified. We evaluated whether different 

standards during startup and shutdown periods are justified, and in this case, we established work 

practice standards to apply during startup and shutdown periods. The decision to use a work 

practice standard is wholly within the discretion of the EPA. CAA section 112(h) (“[T]he 

Administrator may, in lieu [of a numeric standard], promulgate a design, equipment, work 

practice, or operational standard, or combination thereof.”). In exercising the option to establish 

a work practice standard, that standard must “in the Administrator’s judgment [be] consistent 

with the provisions of subsection (d) or (f).” CAA section 112(h)(1) (emphasis added). These 

subsections make clear that the EPA is to base emission standards on the emission levels already 

achieved by the best performing sources and to ensure that public health is protected, as 

applicable. This means that work practice standards, although written in non-numeric form, must 

still satisfy statutory requirements such as those applicable to MACT standards, including the 

requirement to be no less stringent than the MACT floor.

Contrary to the commenter’s argument, we believe that the standards that apply during startup 

and shutdown periods will establish “continuous section 112-compliant standards” that the 

Sierra Club decision concluded are required. We also disagree with the comment that the Sierra 

Club decision “did not by its terms” concern what EPA may or may not include in categoryspecific MACT standards. (Citing letter to counsel from Adam Kushner, Director of EPA’s 

Office of Civil Enforcement, July 22, 2009 (see Table 2 of the letter)). This letter, which 

addressed potential compliance issues arising from the Sierra Club court decision, contained 

EPA’s plans for addressing those concerns, including potential future revisions to section 112(d) 

standards. As explained in the letter, our initial analysis indicated that certain rules, such as the 

mineral wool production NESHAP, included specific regulatory text exempting or excusing 

compliance during SSM events in addition to cross-references to 40 CFR. Sections 63.6(f)(1) 

and 63.6(h)(1). At the time, we indicated that the vacatur in Sierra Club would have no direct 

impact on such source category-specific SSM provisions because we believed these provisions 

were not challenged in Sierra Club. We, however, also recognized that the legality of those 

source-category specific provisions may have been called into question and indicated that we 

were evaluating them in light of Sierra Club. “The tables attached to this letter are based on the 

EPA’s initial analysis and are, therefore, subject to change.” (p. 3) [footnote omitted]. We have 

now evaluated the relevant provisions and determined that they need to be revised to address the 

Sierra Club decision.

We disagree with commenter’s claim that case law under the CAA and CWA supports its 

argument that EPA’s approach to startup and shutdown periods is inconsistent with CAA section 

112. As explained above and in the preamble to the 2013 and 2014 proposed rules, the EPA has 

taken into account startup and shutdown periods in determining appropriate standards. The 
64

relevance of Portland Cement and Essex Chem. Corp. is questionable in light of subsequent case 

law and the 1977 amendments to the CAA definition of emission standard requiring that such 

standards be continuous. As the D.C. Circuit noted in National Lime v. EPA, 627 F.2d. 416, 434 

at n 54, “[w]hether the 1977 Amendments have effectively repealed the regulations permitting 

flexibility to account for startups, shutdowns and malfunctions regulations applauded by this 

court in Portland Cement I, 486 F.2d at 398-99 is certainly unclear.” 

The NRDC v. EPA (859 F. 2d 156, 207(D.C. Cir. 1988)) case cited by commenter interprets 

provisions of the CWA that are different in nature than provisions governing standards under 

section 112 of the CAA. Furthermore, the discussion of technology-based standards in the NRDC

case is dicta. Nevertheless, the EPA’s approach to malfunctions is also consistent with NRDC. 

NRDC does not require exemptions or less stringent standards for malfunction periods. Further, 

the regulatory affirmative defense included in today’s final rule is consistent with the case cited 

in the NRDC decision; Marathon Oil Co. v. EPA, 564 F.2d 1253, 1272 (9th Cir. 1977). The court 

in Marathon Oil held that EPA must formalize its approach to upsets under the CWA. The 

affirmative defense does so. See, Mont. Sulphur & Chem. Co. v. United States EPA, 2012 U.S. 

App. LEXIS 1056 (5th Cir. Jan 19, 2012) (in rejecting industry argument based on Marathon Oil 

that reliance on the affirmative defense was not adequate, court stated “[h]owever, here the EPA 

does not rely on enforcement discretion alone, but specifically promulgates an affirmative 

defense in the FIP, which clearly defines the requirements to avoid penalties.”). But see, 

Weyerhaeuser v. Costle, 590 F.2d 1011, 1057-58 (D.C. Cir. 1978) (holding that an informal 

approach is adequate).

Comment 4: Commenter 0244 requested that EPA revise the work practice standards for 

startup/shutdown in Table 3: Items 2.a.i and 3.a.i, to replace the term “ceramics” with 

“greenware ceramics” to denote unfired ware. It is a standard operating procedure for previously 

fired ware and/or refractory material to be run into a kiln to facilitate start-up and shutdown, and 

these materials do not emit HAP. Adding these materials to a kiln upon start-up or shutdown is 

not a violation of the proposed MACT.

Response 4: The startup and shutdown work practice standards in Table 3 have been revised for 

promulgation and no longer include the term “ceramics,” so the requested revision is no longer 

applicable.
65

11.0 Malfunction

Comment 1: Commenter 0250 stated that it is not possible to test during a malfunction. The 

commenter also stated that because it is not technically or economically feasible to test during 

these periods, malfunctions meet the criteria of section 112(h) of the CAA that allows for work 

practice standards.

Response 1: With respect to the commenter’s suggestion that the EPA consider work practice 

standards for periods of malfunction, the decision to use a work practice standard is wholly 

within the discretion of the EPA. CAA section 112(h) (“[T]he Administrator may, in lieu [of a 

numeric standard], promulgate a design, equipment, work practice, or operational standard, or 

combination thereof.”). In exercising the option to establish a work practice standard, that 

standard must “in the Administrator’s judgment [be] consistent with the provisions of subsection 

(d) or (f).” CAA section 112(h)(1) (emphasis added). These subsections make clear that the EPA 

is to base emission standards on the emission levels already achieved by the best-performing 

sources and to ensure that public health is protected, as applicable. This means that work practice 

standards, although written in non-numeric form, must still satisfy statutory requirements such as 

those applicable to MACT standards, including the requirement to be no less stringent than the 

MACT floor.

It is just as difficult to establish a work practice standard for malfunctions that can approximate 

the level of emission reduction achieved by the best-performing sources during malfunctions as

it would be to factor emission levels that occur during malfunctions into the numeric standards. 

The EPA would have to design a single work practice standard that applies equally to a tank 

explosion as it does to innumerable types of operator error, computer glitches or a myriad of 

other unknown events, or alternatively create innumerable work practice standards.

In summary, the EPA believes that, based on this rulemaking record, it would be clearly 

inappropriate to set a work practice standard for malfunctions in lieu of the otherwise applicable 

numerical emission limit. We also note that we would consider any response to violations caused 

by a malfunction on a case-by-case basis through the exercise of enforcement discretion. 

However, we disagree with the commenter’s suggestion that the EPA limit its discretionary 

authority by affirmatively stating in the final rule that it will not seek administrative penalties for 

excess emissions caused by malfunctions.

Comment 2: Commenter 0250 stated that CAA section 112 does not require or even allow the 

EPA to ignore malfunctions when setting MACT standards. The commenter stated the EPA 

cannot ignore the requirement that MACT floor standards reflect performance actually achieved.

The commenter asserted that statutory language, congressional intent, and case law support EPA 

promulgating alternative emission standards for malfunction events (either numerical limits or 

work practices) . By setting standards for malfunction events, the EPA would not have to affect 

the stringency of the emission standards that apply during normal, steady-state operations.

Commenter 0250 also disagreed with the EPA’s view that applying the concept of “bestperforming” is inconsistent with a source experiencing a malfunction. See 79 FR 75626. The 

commenter argued that best performers experience malfunctions and there are work practices 

(such as monitoring of operating parameters to identify a malfunction and stopping or cutting 
66

back the process accordingly) that represent the best practices for minimizing emissions during a 

malfunction. Commenters 0516, 0533, and 0537 noted that the measures representing these best 

practices will depend on facility-specific issues. 

Commenter 0250 stated that facility-specific best practices represent the “the maximum degree 

of reduction in emissions of the hazardous air pollutants...achievable...through application of 

measures, processes, methods, systems or techniques” and reflect “the emission control that is 

achieved in practice by the best controlled similar source[s]” CAA section 112(d)(2) and (3). 

Commenter 0250 stated that there is no basis for EPA’s conclusion that malfunction events are 

not representative of best-performing sources. See id.; see also, e.g., Cement Kiln Recycling 

Coalition, 255 F.3d at 862-865 (recognizing that there is variability in the performance of control 

technologies, which needs to be taken into account in establishing emission limitations based on 

the MACT floor); Sierra Club v. EPA, 167 F.3d 658, 665 (D.C. Cir. 1999). The commenter 

asked that the EPA acknowledge the fact that best performing sources experience malfunction 

events and not set MACT standards that even the best performing existing sources cannot 

achieve part of the time. The commenter asserted that the EPA is going beyond the MACT floor

without making the demonstrations that the statute and case law require the Agency to make in 

order to impose beyond-the-floor MACT standards (including the Agency’s obligation to 

consider costs). Commenters 0516, 0537, and 0543 concurred with this comment.

Commenter 0250 stated that when a facility experiences exceedances due to a malfunction, even 

though affirmative defense was struck down, the EPA’s response will be based on whether the 

facility had conducted “root cause analyses to ascertain and rectify excess emissions.” 79 FR 

75627. The commenter argued the EPA made no attempt to justify those conditions as 

reasonable “taking into consideration the cost of achieving such emission reduction, and any 

non-air quality health and environmental impacts and energy requirements,” as required by CAA 

section 112(d)(2).

Commenter 0250 stated the EPA should include emissions data representing malfunctions (if 

such data exist) in calculating the MACT floor (see 79 FR 75626) or considering alternative 

work practice standards, instead of requiring that the MACT floor limitations be met even during 

malfunctions. If it is possible to gather sufficient representative data reflecting emissions during 

malfunctions, then the EPA is obligated to consider those data in its MACT floor calculations for 

steady-state operating conditions. To the extent EPA had access to continuous monitoring data 

for emission units covered by the NESHAP, the commenters asserted the EPA could have 

conducted analyses of emissions levels during malfunction events. The commenter stated that 

even if continuous monitoring data are for parameters not regulated by the proposal, the 

monitoring data might form a reasonable basis for EPA’s assessment of what standards are 

achieved or achievable during malfunctions. Also, many types of sources are required by many 

state agencies to submit deviation reports or malfunction reports when they experience a 

malfunction that causes an exceedance of an applicable limitation. The commenters stated that 

the EPA does not appear to have made any attempt to obtain and analyze such reports, in order to 

assess what type of requirement might reasonably apply during malfunctions.
67

Commenter 0250 stated that before affirmative defense was struck down, the Agency believed 

that an affirmative defense provision was necessary so that MACT standards would be based on 

what is achievable with available technology. The EPA not only does not include an affirmative 

defense, it does not explain why it is reasonable to treat exceedances associated with 

malfunctions as violations. The commenter recommended the EPA include many of the concepts 

that it incorporated into the affirmative defense provisions of other recent NESHAP proposals 

into alternative, work practice standards that would apply during malfunctions. They argue that 

this approach would be consistent with NRDC v. EPA.

Commenter 0250 stated that the EPA’s statement “. . . the EPA would 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,” (79 FR 7527) are inadequate. The 

commenter questioned whether there would ever be an appropriate time for EPA not to use its 

enforcement discretion. The EPA has provided no analysis that would supersede its longstanding determination that it is not appropriate to rely on enforcement, rather than regulatory 

language, to address the inability to comply with technology-based standards during SSM events. 

See 37 FR 17214 (Aug. 25, 1972) (establishing SSM provision in NSPS). The commenter 

asserted that the courts have adopted the same view. See, e.g., Portland Cement, 486 F.2d at 398 

n.1; National Lime, 627 F.2d at 431 n.46 (“the flexibility appropriate to enforcement will not 

render ‘achievable’ a standard which cannot be achieved on a regular basis, either for the reasons 

expressly taken into account in compliance determination regulations (here startup, shutdown 

and malfunction), or otherwise.”).18

Commenter 0250 also noted the EPA’s exercise of its discretion not to bring an enforcement 

action for excusable malfunctions does nothing to prevent a source from having to defend itself 

from a citizen suit or state enforcement action for the same malfunctions, nor does the Agency 

state that it will exercise its enforcement discretion for events that meet the criteria it has applied 

in the past to the affirmative defense. The commenter noted that after-the-fact determinations of 

whether or not to penalize a source that has a malfunction do not require or encourage measures 

that may reduce the magnitude or duration of exceedances associated with malfunctions. The 

commenter recommended that the EPA address compliance during malfunctions by 

promulgating an achievable alternative standard.

Commenter 0250 noted in a district court enforcement action or in a citizen enforcement action, 

“similarly, the presiding officer in an administrative proceeding can consider any defense raised 

and determine whether Administrative penalties are appropriate.” 79 FR 75627. The commenter 

noted that in NRDC v. EPA, the Court specifically recognized the EPA has authority to limit the 

 18 See also Marathon Oil Co. v. EPA, 564 F.2d at 1273 (explaining why EPA’s statement that it would not take 

enforcement action against sources that exceeded effluent limitations because of upset events was “not an adequate 

response” to the argument that standards that cannot be met during unavoidable upsets fail to reflect available 

technology). Also for these reasons, the commenter stated that EPA’s statements in the Proposed Rule preamble that 

EPA will “determine an appropriate response” to reported exceedances of the Proposed Standards, 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” (79 FR 75627), are not in any way a substitute for EPA setting the standards at an achievable level in the 

first place.
68

situations in which it will impose administrative penalties in that manner. See 749 F.3d at 1063 

(“By contrast, EPA’s ability to determine whether penalties should be assessed for Clean Air Act 

violations extends only to administrative penalties, not to civil penalties imposed by a court.” 

(citation omitted)). The commenter recommended the EPA affirmatively state in the final rule 

that the Agency will not seek administrative penalties for excess emissions caused by 

malfunctions.

Commenter 0250 noted that in the portion of the proposed rule dealing with air pollution control 

device maintenance, the EPA allowed sources to bypass an APCD under certain circumstances to 

perform control device maintenance(see 40 CFR 63.8420(d)). The commenter stated that 

proposed 40 CFR 63.8420(d) is an example of how EPA has used its work practice authority to 

establish alternative emission standards in situations that are analogous to addressing emissions 

during malfunction events.

Response 2: The EPA disagrees with the comment that it is required to take malfunctions into 

account when adopting MACT standards and that a separate standard be set for periods of 

malfunction. As explained in the preamble, the EPA has determined that CAA section 112 does 

not require that “emissions that occur during periods of malfunction...be factored into 

development of CAA section 112 standards...There is nothing in CAA section 112 that directs 

the agency to consider malfunctions in determining the level “achieved” by the best-performing 

sources when setting emission standards. As the U.S. Court of Appeals for the District of 

Columbia Circuit has recognized, the phrase “average emissions limitation achieved by the best 

performing 12 percent of” sources “says nothing about how the performance of the best units is 

to be calculated.” Nat’l Ass’n of Clean Water Agencies v. EPA, 734 F.3d 1115, 1141 (D.C. Cir. 

2013).”

As we further explained, “accounting for malfunctions in setting emission standards would be 

difficult, if not impossible, given the myriad different types of malfunctions that can occur across 

all sources in the category and given the difficulties associated with predicting or accounting for 

the frequency, degree, and duration of various malfunctions that might occur. For these reasons, 

the performance of units that are malfunctioning is not “reasonably” foreseeable. See, e.g., Sierra 

Club v. EPA, 167 F.3d 658, 662 (D.C. Cir. 1999) (‘‘The EPA typically has wide latitude in 

determining the extent of data-gathering necessary to solve a problem. We generally defer to an 

agency’s decision to proceed on the basis of imperfect scientific information, rather than to 

‘invest the resources to conduct the perfect study.’”)

With respect to the commenters’ suggestion that EPA consider work practice standards, we refer 

to our response to the previous comment.

Comment 3: Commenter 0250 noted that in the proposed rule, the EPA replaced the NESHAP 

General Provisions section that establishes a “general duty” to operate a source consistent with 

safety and good air pollution control practices for minimizing emissions, 40 CFR 63.6(e)(1), 

with somewhat different “general duty” language in proposed 40 CFR 63.8420(b). The D.C. 

Circuit did not vacate the provision EPA replaced, 40 CFR 63.6(e)(1), in Sierra Club v. EPA

(which vacated the “exemption” for SSM events in 40 CFR 63.6(f)(1) and (h)(1), not the 

requirement for good air pollution control practices), and, contrary to EPA’s assertion in the 
69

preamble to the Proposed Rule, 40 CFR 63.6(e)(1) does not reference provisions that were 

vacated in Sierra Club v. EPA. Compare Table 8, 79 FR 75691, and Table 9, Id. at 75716 of the 

Proposed Rule with 79 FR 75626. The Agency must provide a cogent explanation of why the old 

rule was unacceptable and the new rule is necessary. The commenter suggested that the proposed 

new general duty provisions be deleted, and delete proposed 40 CFR 63.8420(b) from the final 

rule. If the EPA does not delete 40 CFR 63.8420(b), the Agency should re-propose the provision 

with some explanation of the basis and purpose for the provision, to allow the public an 

opportunity to provide meaningful comments, as required by CAA section 307(d)(3).

Response 3: Section 63.6(e)(1)(i) describes the general duty to minimize emissions. The current 

language in 40 CFR 63.6(e)(1)(i) characterizes what the general duty entails during periods of 

SSM. With the elimination of the SSM exemption, there is no need to differentiate between 

normal operations, startup and shutdown, and malfunction events in describing the general duty. 

Consequently, we proposed that the entry for 40 CFR 63.6(e)(1)(i) in the General Provisions 

table (Table 8 to Subpart JJJJJ) in column 4 should be “no.” We also proposed adding general 

duty regulatory text at 40 CFR 63.8420(b) that reflects the general duty to minimize emissions 

while eliminating the reference to periods covered by an SSM exemption. Therefore, the 

language the EPA proposed for 40 CFR 63.8420(b) does not include the current language in 40 

CFR 63.6(e)(1). The proposed changes were necessary to clarify the general duty requirements 

in light of the elimination of the SSM exemption. Consequently, we must deny the commenter’s 

request to have proposed 40 CFR 63.8420(b) deleted from the final rule. Reproposal of the 

section, with some explanation of the basis and purpose for the provision, is also unnecessary 

and is denied.

Comment 4: Commenter 0247 stated the EPA has taken inconsistent positions on what a 

“malfunction” is and is not, and how emissions during periods of “malfunction” should be 

handled by this industry. On the one hand, EPA chooses not to define a malfunction for purposes 

of creating a distinct continuous compliance approach during periods of malfunction separate 

from normal operations, stating that the CAA does not require it to separately regulate emissions 

during malfunctions, 79 FR 75626 (cols-2-3)), leaving open the question, of what exactly a 

malfunction is.

The commenter argued that EPA’s proposal forces malfunctions-related emissions to meet the

same requirements as normal operations, despite EPA stating that malfunctions are not normal 

operations. Emissions during these periods are “neither predicable nor routine.” Id. Malfunctions 

are “sudden, infrequent and not reasonably preventable failures of emissions control, process or 

monitoring equipment.” Id. EPA draws the comparison to “upsets” in other regulatory programs 

as the basis for its proposed choice not to define malfunctions (79 FR 75626 (col. 3)). While 

upsets were at one time difficult to define, definition has occurred.

The commenter noted that, in other places in the proposed NESHAP, EPA treated malfunctions 

as if it defined them. For example, EPA prohibited performance testing during “malfunctions”

(79 FR 75696 (col. 2); proposed to be codified at 40 CFR 63.8595(d)). Also, EPA asserted that 

emissions during malfunction periods must be excluded in determining a MACT floor (79 FR 

75627). EPA proposed that an exceedence of an emission limit or an operating limit during a 

“period of malfunction” is a reportable Title V deviation (79 FR 75699-75700; proposed to be 
70

codified at 40 CFR 63.8620(c) and 63.8635(g)). The commenter argued the EPA leads the reader 

to the conclusion that EPA has defined malfunctions.

Commenter 0247 stated that EPA’s reliance on after-the-fact legal enforcement does not assure 

the continuous compliance required by the Courts. EPA has twice recognized that malfunctions 

occur; the fact that the Courts have twice struck down EPA’s attempts to acknowledge and 

address them in the NESHAP context (the Sierra Club case, and as an affirmative defense), does 

not mean that malfunctions do not occur, or that EPA is out of options for accommodating 

malfunctions. EPA has recognized for decades that malfunctions and upsets are part 

manufacturing and has judicial approval for New Source Performance Standards (40 CFR 60.8 

(2014)) that accommodated such events. The CAA has several provisions pursuant to which EPA 

can take the actions. See NRDC v. EPA, 859 F.2d 156, 208 (D.C. Cir. 1988).

The commenter argued that EPA cannot write inconsistent regulations. The commenter

encouraged EPA to develop and propose a definition of malfunction that will be used 

consistently throughout the NESHAP for this subcategory so that the regulated community is 

able to clearly understand what behaviors are lawful and what behaviors are prohibited. With no 

definition of a malfunction, the commenter argued, the public cannot comment on the emission 

standards proposed by EPA. The commenter contended that the regulation, if finalized as 

proposed, would be arbitrary and capricious.

The commenter stated that it is only by reasonably defining malfunctions and creating a 

meaningful, achievable continuous compliance option during them that EPA can avoid the 

inclusion of those emissions in the MACT floor. If emissions during malfunctions are deemed to 

be emissions during normal operations for compliance purposes, they must also be considered to 

be emissions during normal operations for purposes of setting the MACT floor pool. They would 

likewise be eligible for performance testing. If emissions during malfunctions are not deemed to 

be emissions during normal operations and separate standards are set, EPA may avoid these 

outcomes it states in the preamble it is trying to avoid. 

If HAP emissions during periods of malfunction must comply with the same emission limits 

applicable to normal operations, EPA can expect major sources to report deviations in most title 

V certification reports. EPA has a strong incentive to define malfunctions in this rule to avoid 

that situation. Sudden and unpreventable failures of emissions control, process or monitoring 

equipment are far from routine but they are not rare either. Even best performing sources have 

malfunctions.

Response 4: These comments are based on two incorrect premises. First, contrary to the 

commenter’s statements, the EPA has defined malfunctions, in 40 CFR 63.2, and does not need 

to define malfunctions further for this rule. Second, the EPA does not need to factor emissions 

that occur during malfunctions into the emissions standard, or develop a different emissions limit 

or other special rules for malfunctions. The EPA interprets CAA section 112 as not requiring 

emissions that occur during periods of malfunction to be factored into development of CAA 

section 112 standards. Under section 112, emissions standards for new sources must be no less 

stringent than the level “achieved” by the best controlled similar source and for existing sources 

generally must be no less stringent than the average emission limitation “achieved” by the best 
71

performing 12 percent of sources in the category. There is nothing in section 112 that directs the 

Agency to consider malfunctions in determining the level “achieved” by the best performing 

sources when setting emission standards. As the D.C. Circuit has recognized, the phrase 

“average emissions limitation achieved by the best performing 12 percent of” sources “says 

nothing about how the performance of the best units is to be calculated.” Nat’l Ass’n of Clean 

Water Agencies v. EPA, 734 F.3d 1115, 1141 (D.C. Cir. 2013). While the EPA accounts for 

variability in setting emissions standards, nothing in section 112 requires the Agency to consider 

malfunctions as part of that analysis. A malfunction should not be treated in the same manner as 

the type of variation in performance that occurs during routine operations of a source. A 

malfunction is a failure of the source to perform in a “normal or usual manner” and no statutory 

language compels EPA to consider such events in setting section 112 standards.

Further, accounting for malfunctions in setting emission standards would be difficult, if not 

impossible, given the myriad different types of malfunctions that can occur across all sources in 

the category and given the difficulties associated with predicting or accounting for the frequency, 

degree, and duration of various malfunctions that might occur. As such, the performance of units 

that are malfunctioning is not “reasonably” foreseeable. See, e.g. Sierra Club v. EPA, 167 F.3d 

658, 662 (D.C. Cir. 1999) (“The EPA typically has wide latitude in determining the extent of 

data-gathering necessary to solve a problem. We generally defer to an agency’s decision to 

proceed on the basis of imperfect scientific information, rather than to ‘invest the resources to 

conduct the perfect study.’”) See also, Weyerhaeuser v. Costle, 590 F.2d 1011, 1058 (D.C. 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.”). In 

addition, emissions during a malfunction event can be significantly higher than emissions at any 

other time of source operation. For example, if an air pollution control device with 99 percent 

removal goes off-line as a result of a malfunction (as might happen if, for example, the bags in a 

baghouse catch fire) and the emission unit is a steady state type unit that would take days to shut 

down, the source would go from 99 percent control to zero control until the control device was 

repaired. The source’s emissions during the malfunction would be 100 times higher than during 

normal operations. As such, the emissions over a 4-day malfunction period would exceed the 

annual emissions of the source during normal operations. As this example illustrates, accounting 

for malfunctions could lead to standards that are not reflective of (and significantly less stringent 

than) levels that are achieved by a well-performing non-malfunctioning source. It is reasonable 

to interpret section 112 to avoid such a result. The EPA’s approach to malfunctions is consistent 

with section 112 and is a reasonable interpretation of the statute.

In the event that a source fails to comply with the applicable CAA section 112(d) standards as a 

result of a malfunction event, the EPA would 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. The 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).
72

If the EPA determines in a particular case that an enforcement action against a source for 

violation of an emission standard is warranted, the source can raise any and all defenses in that 

enforcement action and the federal district court will determine what, if any, relief is appropriate. 

The same is true for citizen enforcement actions. Similarly, the presiding officer in an 

administrative proceeding can consider any defense raised and determine whether administrative 

penalties are appropriate.

In summary, consistent with Sierra Club v. EPA, the EPA has established standards in this rule 

that apply at all times, including periods of malfunction. The EPA interpretation of the CAA and, 

in particular, section 112 is reasonable and encourages practices that will avoid malfunctions. 

Administrative and judicial procedures for addressing exceedances of the standards fully 

recognize that violations may occur despite good faith efforts to comply and can accommodate 

those situations.

Comment 5: Commenter 0247 argued that the regulated community can assert defenses to 

malfunction-related emissions in excess of emission limits applicable during normal operations, 

citing Weyerhaeuser v. Costle, 590 F.2d 1011 (D.C. Cir. 1978). “The source can raise any and all 

defenses,” the preamble declares (79 FR 75627 (col. 1)). The proposed NESHAP regulation, 

however, made no defenses legally available. The preamble suggested defenses such as good 

faith efforts to minimize emissions, including preventative and corrective actions, as well as root 

cause analyses. The commenter stated it is “illusory, arbitrary and capricious for EPA to assert in 

a preamble that defenses are legally available and then not to include those defenses in its 

regulation.” The commenter also noted that a common definition of “malfunction” for 

compliance and enforcement purposes is also necessary. The commenter contended that EPA’s 

proposed approach creates a new enforcement process for NESHAPs that worsens the situation

and violates Executive Orders. 

Response 5: We disagree with the commenter’s contention that the EPA is obligated to create a 

regulatory affirmative defense that would protect a source that fails to comply with the 

applicable CAA section 112 standards as a result of a malfunction event. 

Though EPA has in the past included such an affirmative defense in some rules, the United 

States Court of Appeals for the District of Columbia Circuit recently vacated an affirmative 

defense in one of the EPA’s Section 112 regulations. NRDC v. EPA, 749 F.3d 1055 (D.C. Cir., 

2014) (vacating affirmative defense provisions in Section 112 rule establishing emission 

standards for Portland cement kilns). The court found that the EPA lacked authority to establish 

an affirmative defense for private civil suits and held that under the CAA, the authority to 

determine civil penalty amounts in such cases lies exclusively with the courts, not the EPA. 

Specifically, the Court found: “As the language of the statute makes clear, the courts determine, 

on a case-by-case basis, whether civil penalties are ‘appropriate.’” See NRDC at 1063 (“[U]nder 

this statute, deciding whether penalties are ‘appropriate’ in a given private civil suit is a job for 

the courts, not EPA.”). In light of NRDC, the EPA is not including a regulatory affirmative 

defense provision in the final rule. If a source is unable to comply with emissions standards as a 

result of a malfunction, the EPA may use its case-by-case enforcement discretion to provide 

flexibility, as appropriate. Further, as the D.C. Circuit recognized, in an EPA or citizen 

enforcement action, the court has the discretion to consider any defense raised and determine 

whether penalties are appropriate. Cf. NRDC, at 1064 (arguments that violation were caused by 
73

unavoidable technology failure can be made to the courts in future civil cases when the issue 

arises). The same is true for the presiding officer in EPA administrative enforcement actions.

Comment 6: Commenter 0247 argued that EPA attempted to justify its proposed approach to 

malfunctions on the Court’s decision in Sierra Club v. EPA, 551 F.3d 1019 (D.C. Cir. 2008), 

cert. denied, 130 S.Ct. 1735 (2010). The commenter stated that EPA’s proposal may be at odds 

with that decision since that case struck down a portion of the NESHAP General Provisions and 

NESHAP category-specific requirements were not before the Court. The Court did not rule that 

category-specific emissions limitations must be the same for periods of normal operations and 

periods of malfunction because malfunctions are a challenging subject or difficult to define.

Response 6: We disagree with the commenter’s suggestion that Sierra Club v. EPA, 551 F.3d 

1019 (D.C. Cir. 2008) is not relevant because it addressed the SSM exemption in the NESHAP 

General Provisions and did not address what EPA may or may not include in category-specific 

MACT standards. The holding in Sierra Club that emissions limitations under section 112 must 

apply continuously is clearly applicable to category-specific MACT standards. Moreover, as 

discussed above, the EPA’s approach to malfunctions in this rule is consistent with the D.C. 

Circuit’s decision in NRDC v. EPA, 749 F.3d 1055 (D.C. Cir. 2014).

Comment 7: According to Commenter 0247, CAA section 112(d) and the courts require 

establishment of NESHAP standards that can be achieved in practice by the regulated 

community. The commenter contended that EPA failed to survey the industry on this subject, as 

it surveyed other subcategories, and thus it has almost no basis for its implied conclusion that 

during a period of malfunction, major sources in this subcategory achieve in practice emissions 

limitations established on the basis of stack testing during normal operations. The commenter 

disputed that major sources in this subcategory always achieve such emissions limitations during 

periods of malfunction. The commenter stated that EPA’s proposal legally must be considered a 

beyond-the floor proposal, which has not undergone that analysis. Therefore, the commenter 

concluded it is unlawful.

Commenter 0247 indicated that their organization provided EPA with PM emissions data for a 

floor tile kiln during periods of malfunction (see 79 FR 75627 (col. 2)) and the citation therein to 

EPA’s “2010 EPA Survey.” (Dec. 18, 2014). EPA could have developed a PM surrogate 

emissions limitation for periods of malfunction from these data. Courts have indicated that EPA 

has the authority to develop NESHAP emissions limitations during periods of malfunction when 

it has actual relevant emissions data. The commenter contended that EPA’s failure to develop a 

PM surrogate emissions limitation for floor tile kilns during periods of malfunction is arbitrary 

and capricious.

By analogy, the commenter also noted that EPA had the opportunity to develop D/F and 

Hg emissions limitations for floor tile kilns during periods of malfunction, and failed to do so. 

The commenter stated that failure is also arbitrary and capricious.

Response 7: As explained in the preamble of the proposed rule, the EPA has determined that 

CAA section 112 does not require that emissions that occur during periods of malfunction be 

factored into development of CAA section 112 standards. While the EPA accounts for variability 

in setting emissions standards, a malfunction is a failure of the source to perform in a ‘‘normal or 
74

usual manner’’ and no statutory language compels the EPA to consider such events in setting 

section 112 standards. Further, accounting for malfunctions in setting emission standards would 

be difficult, if not impossible, given the myriad different types of malfunctions that can occur 

across all sources in the category and given the difficulties associated with predicting or 

accounting for the frequency, degree and duration of various malfunctions that might occur. 

Consequently, we disagree with the commenter that a survey of the industry on the subject of 

malfunctions would have produced data sufficient to establish standards that account for all 

possible malfunctions in the industry, or that we could have used the data they provided from 

one kiln for one pollutant for a limited number and type of malfunctions to establish standards 

that account for all possible malfunctions in the industry.
75

12.0 Testing and Initial Compliance Requirements

Comment 1: Commenter 0244 argued that the temperature operating limit listed in Table 2 for 

sanitaryware kilns does not account for normal temperature variability in a tunnel kiln and is 

unnecessarily restrictive. The commenter requested the temperature limit be set at a temperature 

above 2000 degrees F. Alternatively, the commenter suggested the temperature limit be the 

3-hour block average measured during the performance test minus 100 degrees F. The 

commenter stated that such a limit would not compromise compliance with the MACT. 

The commenter argued that some flexibility in the temperature operating limit is necessary to 

account for normal variability and to allow kiln processes to operate in a manner that meets

market demand, minimizes scrap, fuel consumption and greenhouse gas emissions, and allows

process innovation and optimization.

According to the commenter, scientific literature recognizes incineration as the best available 

method to destroy dioxins/furans and noted The World Health Organization’s Fact Sheet No. 225 

(Dioxins and Their Effects on Human Health - June 2014) states that most published research 

papers on D/F control indicate temperatures over 1000 degrees C (1830 degrees F) are effective 

for D/F destruction. First-fire tunnel kilns operate at over 2000 degrees F and therefore, 

continuous compliance with the D/F emission limitation can be assured by maintaining the peak 

kiln temperature at 2000 degrees F. The commenter requested the operating limit in Table 2:

Item 5.c, be changed to reflect this minimum operating temperature limit. The commenter noted 

the same format was used in the Clay MACT area source rule (subpart RRRRRR), where kiln 

temperature was limited to a maximum of 2800 degrees F and kilns must be fired by natural gas 

or equivalent. Subpart RRRRRR shows a precedent for this type of format for a temperature 

operating limit.

The commenter also noted that peak kiln temperature has some normal day-to-day variation and 

provided time-temperature plot for their first-fire tunnel kiln in Wisconsin. This plot shows the 

same firing cycle on two different days is almost 20 degrees C (68 degrees F) different. The 

commenter noted that establishing an operating limit for peak temperature will be problematic 

because it does not account for normal variability.

According to the commenter, kiln temperature is also related to ware throughput. As throughput 

rates are reduced, operating temperatures can also be reduced, leading to a situation where a kiln 

could violate the temperature operating limit when it scales back production below the level 

achieved during the performance test.

The commenter also provided a pyrometric cone chart from a kiln operating manual showing that 

the temperature variation between fast and slow cycle times can be up to 100 degrees F for any 

specific cone number between cone 6 and cone 10. The chart shows that as kilns migrate from a 

fast cycle cone 10 schedule to a slow cycle cone 6 schedule, the peak temperature in the same 

kiln can drop by over 200 degrees F.

Commenter 0244 stated it is normal for peak kiln temperatures to fluctuate as much as 50 

degrees F from fast to slow cycle times and provided time-temperature plots showing the 

temperature fluctuations for two of their tunnel kilns. The commenter also noted that kiln 
76

temperature is also controlled to meet certain industry standards, such as sanitaryware products 

that are required to meet the ASME A112.19.2 plumbing fixture standard for sale in the United 

States and Canada. Chapter 6.1 of this standard requires all ware to meet a maximum water 

absorption specification. Ware that exceeds this maximum specification must be scrapped. Fired 

ware is checked daily against this specification, and kiln temperature is managed to minimize 

water absorption of fired ware. Sanitaryware facilities need flexibility to manage kiln 

temperature to meet these types of industry standards.

Commenter 0244 stated their company operates its processes as energy efficiently as possible

and investigates process alternatives that may allow vitrification to occur at lower temperatures. 

Even a minor temperature reduction at a kiln can represent a significant reduction in fuel use, 

with an equivalent reduction in greenhouse gas emissions. The commenter stated that facilities 

need flexibility to pursue process strategies without having to repeat performance testing.

Commenter 0244 noted that vitreous sanitaryware plants are highly integrated and noted that it 

takes considerable time (many weeks) to increase production across a facility so that 

performance testing can be completed.

Commenter 0244 further stated that more information is needed on how redoing performance 

tests to set new operational limits can be completed without violating the MACT/permit (Table 

4: Item 4.a). For instance, the source operator may need to decrease production from that 

measured during the previous performance test, which may lead to an operating temperature 

below the previously established minimum. The commenter asked how that can be accomplished 

without violating the minimum temperature limit established in the prior performance test, 

noting that it can take several weeks to optimize a new throughput cycle. While this is being 

done, the kiln may be in non-compliance (under the minimum temperature limit measured during 

the previous performance test) as it migrates to the new throughput rate. The commenter asked 

how this should be handled for MACT compliance demonstration purposes. The commenter 

requested a temporary waiver be available for a source so that when kiln cycle changes are 

implemented they do not result in periods of non-compliance until the performance test is 

redone. The commenter asserted that the optimization period should not be considered noncompliant operation unless a subsequent performance test documents it to be. The commenter

stated that their request to establish a minimum temperature operating limit at 2000 degrees F 

would resolve any compliance issues on this matter, and still allow compliance with the 

dioxin/furan emission limit to be demonstrated.

Response 1: New operational parameters are set by completing a performance test to 

demonstrate compliance and by establishing the new operating parameters that correspond with 

that compliance demonstration. Thus, if a source wishes to change its operating practices such 

that it will no longer meet its applicable operational limits, the source must conduct performance 

testing at the time that it makes the operational change and must establish the new operating 

parameter limits that will be used to monitor compliance. Until the results of the performance

test under the new operational conditions confirm that the facility is in compliance, the facility 

should continue to meet the original operational parameters.

On a related point, because the kiln temperature can vary and no quenching is occurring in the 

process system, a better parameter for demonstrating compliance would be the stack temperature. 

Dioxins and furans are known to form in post-combustion gases in temperature ranges of 200 to 
77

400 degrees C (392 to 752 degrees F),19 so assuring that the maximum stack temperature 

recorded during the compliance test is never exceeded will assure that the dioxin limit is 

continuously met. Therefore, we are revising the requirement by basing the performance 

parameter on the stack temperature and not the kiln temperature. 

Comment 2: Commenter 0247 argued the initial (for D/F) and subsequent (for all proposed 

HAP) performance testing is unlawful and unnecessary due to issues with EPA Method 23 and 

duplication of ongoing Compliance Assurance Monitoring (CAM) and the proposed CPMS. The 

commenter objected to the proposed requirement to conduct initial and subsequent D/F

compliance testing using Method 23 (79 FR 75695 (col. 3)-75696 (col. 1); proposed to be 

codified at 40 CFR 63.8590) because of issues with the reliability, accuracy and validity of 

Method 23. Until Method 23 or another method is developed and validated by EPA for use in the 

context of the ball clay matrix found in the ceramic tile manufacturing industry, the commenter 

contended there is no lawful means to set a D/F standard or to measure compliance.

The commenter also challenged subsequent performance testing, whether within five years after 

NESHAP-proposed initial compliance testing or in connection with the proposed renewal of a 

Title V permit (75,695 (col. 3)-75,996 (col. 1)). The proposed subsequent performance testing is 

duplicative since it overlaps EPA’s CAM program and is unnecessary given the results that EPA 

anticipates will be derived from the proposed CPMS. EPA offers no explanation and suggests no 

value-added associated with subsequent performance testing. EPA and delegated states retain 

discretionary authority to require stack testing where emissions problems at a specific facility are 

reported or evident. This proposed expensive subsequent performance test will be an 

unnecessary burden on the regulated community that EPA has not justified, and is arbitrary and 

capricious.

Commenter 0247 recommended the EPA adopt the approach taken to stack testing in the March 

2010 ICR. Major sources should have the option to designate like sources as representative and 

to test the compliance status of one, or at least fewer than all of them. Since this was acceptable 

to EPA in the ICR context, the commenter saw no valid objection to the continuation of this 

practice. Failure to allow designation of like sources and to consider testing results to be 

representative would be arbitrary and capricious.

Response 2: The EPA disagrees with the commenter, since initial compliance testing and 

follow-up testing for D/F are necessary for showing compliance with the emission limit, setting 

the CAM requirements, and complying with the proposed CPMS operating limits.

The EPA also disagrees with the commenter’s contention that, because the ICR did not require 

testing of every stack at a facility, compliance status should be demonstrated by representative 

sources. ICRs are used to gather information. However, actual stack testing after promulgation is 

required to demonstrate compliance. Choosing several sources for compliance status is not an 

option, since it is unknown whether the remaining facilities are in compliance. Each source is 

 19 Observations on the Effects of Process Parameters on Dioxin/Furan Yield in Municipal Waste and Coal Systems, 

Gullett, Brian K. and Raghunathan K., Chemosphere, Vol 34 Nos 5-7, p. 1027, 1997.
78

different and will have different test results. For compliance, it is essential to have stack tests for 

each source.

Comment 3: Commenter 0247 argued that proposed Table 4, rows 2 and 11 impose erroneous 

PM performance test requirements on glaze spray operations. The glaze spray operations in this 

subcategory occur in a “glaze spray booth,” as defined in proposed 40 CFR 63.8665 (commonly 

described in the ceramic tile manufacturing industry as a “cabinet”). Baffles at the entry and exit 

of these cabinets keep sprayed glaze in the cabinet.

The commenter noted that EPA proposed to regulate HAP emissions from those glaze lines at 

major source ceramic tile manufacturing facilities whose glaze spraying operations emit HAP, 

unless the spray glazes used in those operations satisfy the proposed exemption in 40 CFR 

63.8540(c)(3), Table 1, rows 5 and 15.20 EPA refers to the entire glaze line over twenty times in 

the preamble and in the proposed NESHAP, most critically in the emission standards presented 

in proposed Table 1, rows 5 and 17,21 and the comparable provisions in Tables 6 and 7.

Commenter 0247 stated that EPA must alter proposed Table 4, rows 2 and 11 to meet its 

intentions22 and to assure consistency with Table 1. Table 4 proposes measurement of emissions 

from glaze spray operations. These requirements should be deleted because compliance is not 

measured for the glaze spray operations standing alone; it is measured for the entire glaze line, 

Table 1, rows 5 and 15.23 HAP emissions, if any, from glaze spray operations are irrelevant to 

the Table 1 compliance determination. Moreover, in most ceramic tile manufacturing facilities, 

emissions from glaze spray operations are not separately routed to a pollution control device; 

they are commingled with emissions from other glazing line activities and routed to a common 

control device. Thus, their physical measurement independent of those other activities is 

unworkable. Failure to delete the Table 4 performance testing requirements for glaze spray 

operations would be arbitrary and capricious.

Response 3: The EPA thanks the commenter for this comment. Given the various terms used for 

glaze spraying in the Clay Ceramics manufacturing industry, the term “glaze spray operation” 

was used generically at proposal to refer to all types of glaze spray application when a 

requirement (such as emissions testing) applies to all types of glaze spraying, including tile glaze 

lines with glaze spraying and glaze spray booths such as sanitaryware manual glaze application, 

sanitaryware spray machine glaze application, and sanitaryware robot glaze application. A

definition for “glaze spray operation” has been added to the final rule to clarify the meaning of 

this term.

Comment 4: Commenter 0244 noted that nowhere in the rule is non-operating equipment 

addressed. The commenter asked whether, if a kiln is not operational during the period of the 

required performance testing, it would need to be turned on just for performance testing. The 

commenter requested that non-operational equipment not be restarted just to complete 

performance testing, and that performance testing be done within 180 days of whenever the 

 20 79 FR 75704 and 75694 (Dec. 18, 2014) (proposed to be codified as Table 1 of 40 CFR Part 63, Subpart 

KKKKK).

21 Id. at 75704 (Dec. 18, 2014) (proposed to be codified as Table 1 of 40 CFR Part 63, Subpart KKKKK). 22 Id. at 75706 (Dec. 18, 2014) (proposed to be codified as Table 4 of 40 CFR Part 63, Subpart KKKKK). 23 Id. at 75704 (Dec. 18, 2014) (proposed to be codified as Table 1 of 40 CFR Part 63, Subpart KKKKK).
79

equipment is next put into service. The commenter stated this approach is consistent with how 

this issue is addressed in the Boiler MACT rule (Subpart DDDDD).

Response 4: The final rule does not require that an idled source be turned on just to perform a 

performance test. The General Provisions already cover the case where a source goes beyond the 

required date of the performance test because it is idled (40 CFR 63.7(a)(4)), and it is not 

necessary to specifically address or otherwise take any action on that issue in this rule. The 

General Provisions state that once the source is started up, performance testing is required to be 

completed within 180 days of starting up the source (40 CFR 63.7(a)(2)).

Comment 5: Commenter 0244 stated that average scrubber liquid flow rate and scrubber 

chemical feed rate should be deleted from Table 4 (items 7.c and 8), as they are secondary 

parameters unnecessary for compliance determination.24

Response 5: The EPA disagrees with the commenter on one point. The EPA disagrees that 

scrubber liquid flow rate is not an essential parameter. The packed bed scrubbers installed on 

kilns to control acid gas emissions are designed to operate at a specific liquid-to-gas ratio to 

ensure adequate gas-to-liquid contact in the scrubber. Maintaining adequate liquid flow in the 

scrubber is essential to scrubber performance. However, we do agree with the commenter that it 

is not necessary to monitor scrubber chemical feed rate. As long as the scrubber liquid pH is 

maintained at or above the level determined during the performance test, the chemical addition 

rate is simply not relevant. Scrubber pressure drop is also not a good indicator of performance 

for either PM or acid gases for this type of scrubber. Therefore, we have modified the operating 

parameter requirements for this type of kiln to state that scrubber liquid pH and scrubber liquid 

flow rate must be monitored, and have removed the requirements to monitor chemical addition 

rate and scrubber pressure drop. This revision has been made to both the clay ceramics and 

BSCP manufacturing rulemakings, since this issue is the same for both industries. Nonetheless,

requests for approval of alternate monitoring procedures to the Administrator can be submitted

according to the General Provisions under 40 CFR 63.8(f). The EPA understands that each 

facility may have different configurations and different parameters for monitoring.

Comment 6: Commenter 0244 noted that Table 6, item 4.a requires a production rate limit be 

established for compliance with the HCl-equivalent emission rate during the performance test. If 

the performance test shows maximum potential HCl-equivalent emissions from the facility do 

not have the potential to exceed the limitation in Table 1, then the commenter believed no 

throughput operating limit is needed and throughput monitoring is not required. The commenter 

requested EPA confirm their interpretation of the rule provisions is correct.

Response 6: The EPA agrees with the commenter. Clarifying language has been added to the 

operating limit in Table 2 for the final rule.

Comment 7: Commenter 0244 requested Table 6, item 22 be revised because each batch 

processed in a shuttle kiln consists of a combination of products. Shuttle kiln cycles are not 

developed on a “per product” basis, but time and temperature cycles are programmed and 

tracked for each batch. This condition should be reworded to remove reference to “a designed 

firing time and temperature cycle for each product produced...”

 24 See Commenter 0244’s comments for Table 2, items 2.c and d.
80

Response 7: The EPA agrees with the commenter’s request and has revised Table 6 for the final 

rule accordingly. Similar text has also been revised in 40 CFR 63.8640(c)(7)(i)-(ii), Table 3 and 

Table 7 for the final rule.

Comment 8: Commenter 0244 asked how kiln compliance should be determined for the D/F

concentration limit in Table 1, Item 4.c if multiple stacks are tested. The commenter asked 

whether an air flow-weighted average will need to be calculated to determine compliance with 

this limitation and recommended the rule specify how this should be done.

Response 8: The Administrator or delegated authority should be consulted if an alternative test 

plan is required for multiple stack testing.. If an alternative test method needs to be applied,

approval must be given by the Administrator according to the General Provisions under 40 CFR

63.7(c).

Comment 9: Commenter 0244 made several requests for EPA to change process rate references 

in the rule from “fired product” to “greenware,” as this is the measure most often used for 

production rate tracking and how the commenter’s company specifically reported process rate 

data for the ICR test reports. The following specific changes were requested:

• 40 CFR 63.8595: How do I conduct performance tests and establish operating limits?: 

Several of the equations presented in this part reference process rate as “fired product”

(i.e., Equation 1 variables “MP” and “P”). These references should all be changed to 

“greenware product.”

• Table 4: Item 4.a: This condition states that the operating limit for tunnel kiln process rate 

is based on HCl-equivalent emissions testing. The requirement references equation 6, 

which identifies “fired product” for variable “Capi.” The commenter requested 

“greenware” be identified for process weight monitoring, not fired product.

• Table 4: Item 5: This condition states the production rate must be on a fired-product 

weight basis. The commenter requested greenware be used for process weight 

monitoring.

• Table 6: Item 4.a and a.i: The PM emission limit unit of measure should be tons of 

“greenware,” not “fired product.”

• Table 6: Item 4.b and b.i: The Hg emission limit unit of measure should be tons of 

“greenware,” not “fired product.”

• Table 6: Item 14: References to “fired product” should be changed to “greenware,” as 

previously discussed.

Response 9: Because Equations 1 and 6 and Table 4: Item 5 are intended to apply to both 

sanitaryware and ceramic tile kilns, the EPA cannot grant the commenter’s request to change 

“fired product” to “greenware product.” While the production rates reported by the sanitaryware 

company in their section 114 survey responses are in terms of “greenware fired” into the kiln, the 

production rates reported by the ceramic tile companies are in terms of “fired product” coming 

out of the kiln (as requested in the section 114 survey). However, we have changed the term 

“fired product” in Equations 1 and 6 and Table 4: Item 5 to the more generic term “throughput” 

to eliminate any inconsistency with how the commenter’s company reported their production 

rates. The EPA agrees with the commenter’s request to revise Table 6: Items 4 and 14, which are 

specific to sanitaryware, and has made the revisions for the final rule as suggested.
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Comment 10: Commenter 0244 noted that several of the equations presented in 40 CFR 63.8595 

(How do I conduct performance tests and establish operating limits?) reference process rate as 

“tons glaze sprayed” (i.e., Equation 2 variables “MG” and “G”). These references should state 

the glaze application rate is the quantity of first fire glaze sprayed per hour on a dry basis. The 

commenter specifically reported process data as tons first-fire glaze sprayed, on a dry basis, for 

the ICR test reports. The commenter also requested unit of measure for the PM emission limit be 

tons 1F glaze sprayed (dry basis) in Items 6-8 and 16-18 in Table 6.

Response 10: The EPA agrees with the commenter’s request and has revised 40 CFR 63.8598 

and Table 6 for the final rule as suggested. Similar text has also been revised in Table 1 for the 

final rule.

Comment 11: Commenter 0244 requested clarification from EPA about whether the term “3-

hour performance test” used in Table 6 (Items 4.a.ii, 4.b.ii, 4.c.ii, and 6-8) means three 1-hour 

runs, asking if this was EPA’s intent based on 40 CFR 63.8595(e).

Response 11: The EPA agrees with the commenter’s interpretation of the term “3-hour 

performance test.” The term is referring to the combination of three 1-hour test runs.
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13.0 Continuous Compliance Requirements

Comment 1: Commenters 0244 and 0247 disagreed with the proposed monitoring requirements 

in 40 CFR 63.8600(a)(2). Commenter 0244 stated that the proposed requirement that the 

continuous monitoring system (CMS) complete a minimum of one cycle of operation for each 

successive 15-minute period does not align with how tunnel kilns operate, and is not applicable 

to tracking greenware throughput for a tunnel kiln. A new kiln car is typically pushed into a 

tunnel kiln every 20-30 minutes. As proposed, this will result in many 15-minute values being 

zero, which is not meaningful for determining hourly rates, or even 3-hour block average rates 

(40 CFR 63.8600(a)(3)). It is standard kiln practice to document throughput on a daily basis, and 

so while an hourly push rate can be calculated, it is based on the daily throughput value, not on a 

collection of values recorded every 15-minutes for one or two hours. As proposed, this 

monitoring requirement documenting tunnel kiln process rates unworkable. Commenter 0244 

requested the hourly process rate be determined from the daily total throughput to more 

accurately account for the push rate schedule.

Commenter 0244 similarly objected to the requirement in 40 CFR 63.8615(b) for continuous

monitoring when the affected source is operating (except for periods of monitor malfunctions, 

associated repairs, and required QA or control activities). As explained above, continuous 

monitoring for tunnel kiln ware throughput cannot occur in a manner that will allow reasonable 

hourly rates or 3-hour block average rates to be determined. The commenter requested hourly 

ware throughput values be determined from daily throughput monitoring.

Commenter 0247 stated the EPA had not provided a satisfactory explanation in the docket for 

this unusually short averaging period. The commenter recommended the proposed monitoring 

requirements be replaced with daily, monthly and/or annual requirements consistent with 

existing state and federal air permit requirements. The requirement as proposed provides no 

incremental compliance value, and is arbitrary and capricious.

Response 1: For parameter monitoring, the final rule uses a 3-hour block average. EPA based 

the operating parameter 3-hour block average on the estimated sampling time required to 

perform a three run performance test under this rule. However, the commenter appears to think 

that the requirements of the CMS 15-minute measurements apply to throughput. This is not 

correct: the requirements apply to continuously measured parameters, such as control device 

pressure drop.

Comment 2: Commenter 0247 challenged EPA’s proposal of semi-annual calibration of the 

flow sensor in each liquid flow measurement device subject to the proposed NESHAP79 FR 

75698 (col. 2); proposed to be codified at 40 CFR 63.8600(b)(3)). The commenter recommended

the semi-annual calibration of flow sensors be replaced with a requirement to adhere to the 

sensor manufacturer’s written specifications and recommendations. The industry has adhered to 

flow sensor manufacturers’ maintenance specifications and recommendations for at least a 

decade and their use was satisfactory to EPA and state agencies. EPA offered no reason why 

adherence to the manufacturer’s written specifications and recommendations should not be the 

approach taken in this NESHAP. The commenter noted the EPA proposed bag leak detection 

(BLD) systems be “installed, operated, calibrated and maintained in accordance with the 

manufacturer’s written specifications and recommendations” (79 FR 75698 (col. 2-3); proposed 
83

codified at 40 CFR 63.8600(e)(l)). Since EPA allows this approach for BLD, it would be 

arbitrary and capricious for EPA to not take the same approach for flow sensors, or at least offer 

it as an alternative.

Commenter 0247 stated that the EPA should be aware that calibration often requires removal of 

the sensor from service. Removal of these sensors for calibration purposes may result in a 

violation of one or more non-NESHAP air quality requirements. The industry will consider this 

routine maintenance of control equipment. EPA should not require calibration of equipment that 

must be removed from service, unless calibration is specified by the manufacturer’s 

recommendations. The commenter concluded that the requirement as proposed is arbitrary and 

capricious.

Response 2: Semi-annual calibrations of flow sensors ensure that the monitoring equipment are 

properly installed and maintained. EPA believes that, as finalized, the monitoring, 

recordkeeping, and reporting requirements of the rule are the minimum necessary to determine 

continuous compliance. The requirements are generally consistent with the NESHAP general 

provisions and are reasonably consistent with other NESHAPs. The monitoring systems require 

periodic inspection, maintenance, and calibration to ensure continued accuracy. The EPA 

believes the proposed requirements for ensuring data quality and for site-specific monitoring 

plans (where applicable) are reasonable and contends that the information required in the sitespecific monitoring plans is necessary for regulators to ensure that the monitoring equipment are 

properly installed and maintained. The required information provides a written record of the 

calibration, maintenance, data quality, and recordkeeping and reporting procedures to be 

followed by the facility. EPA also notes that owners / operators can always seek approval for 

Operating Maintenance and Monitoring (OM&M) plan. The EPA intends that actions to deal 

with problems associated with monitor malfunction and instrument calibration for affected 

sources be addressed in the OM&M plan. The agency also believes that owners / operators can 

develop procedures in the OM&M plan to calibrate parameter measurements without causing 

safety or environmental release incidents.

Comment 3: Commenter 0247 challenged EPA’s proposed requirement for monthly inspections 

of electrical connections in pressure measurement devices subject to the proposed NESHAP (79 

FR 75698 (col. 2); proposed codified at 40 CFR 63.8600(c)(7)). The commenter recommended

the proposed monthly inspections be replaced with a requirement to follow the manufacturer’s 

written specifications and recommendations. The electrical department of a major source ceramic 

tile manufacturing facility routinely checks electrical connections in these devices according to 

manufacturer’s written specifications and recommendations and good electrical practices. 

Inspections, whether visible or mechanical, are recorded, and adjustments made to equipment to 

the extent necessary. In practice, these electrical connections are not known to fail in large part 

because of integrity of the equipment and because these inspections are successful.

The commenter noted that EPA’s BLD proposal relies on manufacturer’s written specifications 

and recommendations (79 FR 75698 (col. 2-3)). Since EPA allows this approach for BLD, it 

would be arbitrary and capricious for EPA not to allow this approach or at least offer it as an 

alternative to the ceramic tile industry. EPA offers no reason in the docket that adherence to the 

manufacturers’ written specifications and recommendations and good electrical practices should 
84

not be the approach taken with respect to these electrical connections. The commenter concluded 

that EPA’s proposal is arbitrary and not supported by the docket.

Response 3: As stated by the commenter, the electrical department of a major source ceramic 

tile manufacturing facility responsibly and routinely checks electrical connections in these 

devices according to manufacturer’s written specifications and recommendations and good 

electrical practices. Inspections, whether visible or mechanical, are recorded, and adjustments 

made to equipment to the extent necessary. EPA believes the monthly inspections will ensure 

that the electrical connections in the pressure measurement devices are properly maintained.

Comment 4: Commenter 0247 challenged the proposed requirement for calibration of the pH 

meter in pH measurement devices subject to the proposed NESHAP once every eight (8) hours 

(79 FR 75698 (col. 2); proposed to be codified at 40 CFR 63.8600(d)(3)). The commenter 

recommended these proposed calibration requirements be replaced with a requirement to follow

manufacturer’s written specifications and recommendations. The industry already adheres to 

manufacturers’ written specifications and recommendations, and have been satisfactory to EPA 

and state agencies. The commenter also noted EPA’s BLD proposal relies on manufacturer’s 

written specifications and recommendations (79 FR 75698 (col. 2-3)). Since EPA allows this 

approach for BLD, it would be arbitrary and capricious for EPA to not allow this approach for 

the ceramic tile industry. EPA offered no reason why adherence to the manufacturer’s written 

specifications and recommendations should not be the approach taken for pH meters. 

The commenter stated the EPA should be aware that calibration often requires removal of the pH 

meter from service, which may result in a violation of one or more non-NESHAP air quality 

requirements. The industry will consider calibration to be routine maintenance of control 

equipment. According to the manufacturer’s written specifications and recommendations, 

comparison and not calibration assures continuous readings. Calibration should not be required, 

unless specified by the manufacturer’s written specifications and recommendations. The 

commenter concluded that the requirement as proposed is arbitrary and capricious.

Response 4: The pH meter check language has been modified to call for a one point calibration 

daily, and not a two point calibration every 8 hours of process operations. The EPA believes that, 

as finalized, the monitoring, recordkeeping, and reporting requirements of the rule are the 

minimum necessary to determine continuous compliance and are not overly burdensome. The 

requirements are generally consistent with the NESHAP general provisions and are reasonably 

consistent with other NESHAPs. The monitoring systems require periodic inspection, 

maintenance, and calibration to ensure continued accuracy. The EPA believes the proposed 

requirements for ensuring data quality and for OM&M plans (where applicable) are reasonable 

and contends that the information required in the site-specific monitoring plans is necessary for 

regulators to ensure that the monitoring equipment are properly installed and maintained. The 

required information provides a written record of the calibration, maintenance, data quality, and 

recordkeeping and reporting procedures to be followed by the facility. The EPA also notes that

owners / operators can always seek approval for site-specific monitoring. This could include, as

some commenters noted, requesting alternative calibration frequencies using consensus-based

approaches that can require fairly sophisticated analyses of past experience and failure rates. The

agency also believes that owners / operators can develop procedures to calibrate parameter

measurements without causing safety or environmental release incidents.
85

Comment 5: Commenters 0244 and 0247 challenged EPA’s proposed requirement 

for semiannual calibration checks for temperature sensors (79 FR 75,622 at 75,699 (col. 1); 

proposed to be codified at 40 CFR 63.8600(g)). Commenter 0247 argued no new temperature 

monitoring requirement should be imposed, provided the major source facility is capable of 

demonstrating through production monitoring equipment that the relevant temperature in any 

given unit is above 450 degrees C or below 200 degrees C. The commenter stated this approach 

reflects the monitoring and testing requirements memorandum in EPA’s docket.25 The 

Commenter 0247 stated that the proposed regulation, if finalized with a temperature sensor 

requirement, would be arbitrary and capricious.

If EPA decides not to withdraw the proposed temperature sensor monitoring requirement, 

Commenter 0247 noted that adherence to the manufacturer’s written specifications and 

recommendations is the best approach. The commenter noted that its members’ actual experience 

with temperature monitoring equipment built in to the process equipment device in this industry 

has been excellent. It is among the most reliable of measurement devices it uses since it is critical 

to assure production quality. The industry adheres to temperature sensor manufacturer’s written 

specifications and recommendations for accuracy checks and/or replacement. Commenter 0244 

also recommended that all sensor calibration checks should be based on the manufacturer’s 

recommendations, and asserted these checks should not arbitrarily be assigned a schedule of “at 

least semiannually,” as specified in 40 CFR 63.8600(g)(3). Commenter 0244 requested that this 

condition be revised accordingly.

Commenter 0244 challenged proposed 40 CFR 63.8600(g)(2), stating a one percent or less 

temperature sensitivity bears no relationship to any emission standard in the proposed NESHAP. 

The commenter argued that the temperature measurement is irrelevant to D/F formation because 

no new D/F is formed in the clay ceramics industry. EPA recommends that the monitoring 

equipment assure operations reflect these ranges,26 not that the sensors have a one percent 

tolerance. A requirement that sensors irrelevant to NESHAP maintain a narrow temperature 

tolerance is arbitrary and unnecessary to the NESHAP goal of continuous compliance.

Finally, Commenter 0247 commented that temperature sensors must be “compared” and not 

“calibrated.” Calibration typically requires removal of the device from service, per manufacturer 

specifications. During calibration, temperature measurements do not occur and hence calibration 

may result in a violation of one or more non-NESHAP air quality requirements. For some 

sensors, calibration is not possible. For those sensors that are possible to calibrate, the industry 

will consider calibration to be routine maintenance of control equipment. However, the 

commenter argued that calibration should not be required, unless specified by the manufacturer’s 

written specifications and recommendations. Commenter 0247 concluded the proposed 

calibration requirement is arbitrary and capricious.

 25 Monitoring and Testing Requirements and Costs for Clay Ceramic NESHAP, at page 2 (Nov. 6, 2014). Docket 

Item No. EPA-HQ-OAR-2013-0290-0229. 26 Id.
86

Response 5: Semi-annual calibrations of temperature sensors ensure that the monitoring 

equipment are properly installed and maintained. The EPA disagrees that temperature is 

irrelevant to D/F formation. For further discussion on this issue, see Section 13.0 Continuous

compliance Requirements Response 12. The EPA believes that, as finalized, the monitoring, 

recordkeeping, and reporting requirements of the rule are the minimum necessary to determine 

continuous compliance and are not overly burdensome. The EPA agrees with the commenter that 

calibration is and should be routine maintenance of the control device. The requirements are 

generally consistent with the NESHAP general provisions and are reasonably consistent with 

other NESHAPs. The monitoring systems require periodic inspection, maintenance, and 

calibration to ensure continued accuracy. The required information provides a written record of 

the calibration, maintenance, data quality, and recordkeeping and reporting procedures to be 

followed by the facility. The EPA also notes that owners/operators can always seek approval for 

site-specific monitoring. This could include requesting alternative calibration frequencies using 

consensus-based approaches that can require fairly sophisticated analyses of past experience and 

failure rates. The Agency also believes that owners/operators can develop procedures to calibrate 

parameter measurements without causing safety or environmental release incidents.

Comment 6: Commenters 0244 and 0247 challenged the operating limits in Table 2 proposed 

for kilns equipped with wet scrubbers. Commenter 0247 argued that packed bed wet scrubber 

technology manufacturers do not provide warranties for abatement of PM emissions. It is 

designed to control HF, HCl, and other non-HAP acid gases. Proposed Table 2, items 2.a and 2.c 

state or imply that these wet scrubbers are expected to abate PM in PM performance tests (79 FR 

75695; proposed to be codified as Table 2 of 40 CFR 63, Subpart KKKKK); the commenter 

contended that they will not and that these proposed requirements are inapplicable and must be 

removed. The commenter stated failure to do so would be arbitrary and capricious.

Commenter 0244 requested that items 2c (scrubber liquid flow rate) and 2d (scrubber chemical 

feed rate) be removed from Table 2 and items 2.a.iii (scrubber liquid flow rate) and 2.a.iv 

(scrubber chemical feed rate) be removed from Table 7 because they add no value for 

compliance assurance. The commenter noted these two items are secondary parameters to the 

parameters the scrubber pressure drop and scrubber liquid pH and that any deviation is 

immediately detected by monitoring pressure drop and pH. Only the pressure drop and pH are 

needed to assure proper operation of the scrubber. Also, there are some scrubber designs (i.e., 

orifice plate scrubber) that do not actively circulate scrubber liquid and so item 2c in Table 2 and 

item 2.a.iv in Table 7 are not universally applicable.

Response 6: The EPA disagrees with the commenters on two points. First, the manufacturers’ 

warranties concerning PM removal are not relevant. Though packed bed scrubbers are primarily 

designed to remove acid gases, some PM removal would be expected to occur. Therefore, 

ensuring the scrubber is performing at the level demonstrated during the compliance test is 

important from the perspective of both PM and acid gas removal. The EPA also disagrees that 

liquid flow rate is not an essential parameter. Packed bed scrubbers are designed to operate at a 

specific liquid-to-gas ratio to ensure adequate gas-to-liquid contact in the scrubber. Maintaining 

adequate liquid flow in the scrubber is essential to scrubber performance. However, we do agree 

with the commenters that it is not necessary to monitor all four parameters. It is the scrubber pH 

that drives the acid gas removal rate. As long as the pH is maintained at or above the level 

determined during the performance test, the chemical addition rate is simply not relevant. 
87

Scrubber pressure drop is not a good indicator of performance for either PM or acid gases for 

this type of scrubber. Therefore, we have modified the operating parameters requirements to 

state that pH and liquid flow rate must be monitored, and have removed the requirements to 

monitor chemical addition rate and scrubber pressure drop. This revision has been made to both 

the clay ceramics and BSCP manufacturing rulemakings, since this issue is the same for both 

industries.

Comment 7: Commenter 0247 accepted the following parameters for continuous monitoring in 

relation to the manufacturer’s written specifications, as applicable to sources subject to a final 

NESHAP:

1. Pressure drop

2. Dry sorbent feed rate

3. Scrubber recirculation water flow rate

4. Scrubber recirculation water pH

5. Kiln firing temperature

6. Tile dryer temperature

7. Hours of routine control device maintenance

8. Method 22 and 9 observations/measurements, if required to be performed.

Response 7: The EPA has outlined in the final rule what parameters are necessary to ensure 

proper operations of the process and control devices and to ensure continuing compliance with 

emission standards. If specific monitoring parameters do not correlate to the site specific control 

devices, the delegated authority can be petitioned for alternative monitoring options.

Comment 8: Commenters 0244 and 0247 objected to EPA’s proposed approach in 40 CFR 

63.8620(e) to include visible emissions (VE) observations as a continuous compliance option (79 

FR 75699 (col. 3)) and recommended the VE requirement be deleted. Commenter 0247 noted 

that spray dryers, tile dryers, glaze spray operations and kilns are subject to VE and/or PM 

emissions limits established in state air permits and regulations. EPA’s proposal to establish a 

VE requirement for exhaust gases composed of both non-HAP particulate and possibly HAP 

particulate is technically infeasible and beyond EPA’s CAA section 112(d) authority. The 

commenter noted that EPA’s records indicate the percentage of HAP in the overall kiln 

particulate loading ranges from a high of 3 percent to a low of 0.5 percent. The commenter 

asserted the EPA does not have the authority to regulate the other 97-99.5 percent that is nonHAP particulate and therefore, the proposed VE requirement is unlawful, arbitrary and 

capricious.

Commenter 0247 further argued the proposed VE requirement would be inconsistent and 

possibly conflict with state VE requirements. The commenter noted state VE requirements are 

sufficiently stringent and it would be arbitrary and capricious for a final NESHAP to negate or 

supersede VE limitations in state permits on the basis that a very small fraction of the PM 

resulting in VE might be a HAP. The commenter argued that NESHAP compliance should be 

deemed achieved if a source is in compliance with its state air permit. 

Commenter 0244 argued the EPA’s data show a PM emission rate of approximately 0.2 lb/hr and 

noted that there are no visible emissions associated with this magnitude of emissions. There are 
88

only a few reasons that may lead to increased VE from a tunnel kiln (i.e., malfunction of the 

combustion gas train, kiln car malfunction (wreck)), and none are associated with increased 

metal HAP emissions. The commenter stated that none of these occurrences correlate with HAP 

emissions from the ware, and each occurrence will be readily detectable by process operators 

before any daily VE reading is made. The commenter further noted that all of their first-fire 

tunnel kilns are natural gas-fired (propane as backup) and that there are no active processing of 

materials in kilns. Sprayed greenware is placed on kiln cars and the kiln cars transported from 

the kiln entrance to the kiln exit. This process does not generate any significant particulate 

emissions. The commenter stated that kiln temperature monitoring is sufficient to document 

compliance and is also consistent with the monitoring required under the Clay MACT area 

source rule (subpart RRRRRR). The commenter stated the VE requirement should be deleted as 

it is costly to conduct, does not add to compliance assurance, and is unnecessary because the kiln 

temperature monitoring is sufficient to demonstrate kiln performance and process control.

Commenter 0244 also noted that most tunnel kilns have two or three cooling exhaust stacks, in 

addition to the primary exhaust stack (POC - products of combustion). The commenter stated 

that daily VE readings at cooling exhausts should not be required because these stacks have no 

VE under any circumstance. The commenter further noted that test data show PM emissions 

from tunnel kiln POC stacks are very low and the stack exhaust contains no VE. The commenter 

also argued that test data has not shown increased VE are related to increased HAP emissions.

Response 8: As noted by Commenter 0244, there are only a few reasons that may lead to 

increased VE from a tunnel kiln (i.e., malfunction of the combustion gas train, kiln car 

malfunction (wreck). If VE are seen, it is an indicator that there is an issue with the process and 

the process needs to be inspected and fixed. There are daily visual emission readings required in 

the Clay MACT area source rule (subpart RRRRRR). Also the rule does not require VE readings 

at cooling exhaust stacks, but rather only at kiln exhaust stacks.

Comment 9: Commenter 0247 proposed two alternatives to EPA’s proposed daily Method 22 

VE observations, fabric filter pressure drop and Method 9 opacity measurements.

In the first alternative, Commenter 0247 proposed daily reading and recording of fabric filter 

pressure drop using a magnahelic gauge or other equivalent pressure measurement device as an 

alternative. The magnahelic gauge or other equivalent pressure measurement devices are 

objective and have a long-standing record in the industry of quality and accuracy, in contrast to 

the VE observations that are subjective. Pressure gauges have been specified, preferred by, and 

satisfactory to EPA and delegated states in other contexts where VE observation was an 

alternative. The commenter argued there is no basis for EPA to not, at a minimum, add pressure 

gauges as an alternative option.

In the second alternative, Commenter 0247 recommended sources have the option, but not the 

obligation, to conduct Method 9 opacity measurements for the stack or stacks in 

geographic/operational proximity to a Method 22 noncompliant observation or non-compliant 

magnahelic measurement and to base their compliance determination and title V deviation 

reporting on the results of the Method 9 measurement. The commenter asserted 40 CFR 

63.8620(e)(3) is inconsistent with Title V and state air permit provisions and the changes the 

commenter recommended would be more consistent with the title V program. The commenter 
89

stated there is nothing in the docket at odds with their recommendation and failure to adopt it 

would be arbitrary and capricious.

Response 9: The EPA thanks the commenter for their comments. The fabric filter pressure drop 

is not an effective means by which to detect changes in performance of a fabric filter relative to 

compliance. The BLD systems alert the operator or owner of an issue in the baghouse. Pressure 

drop is not an early indicator of continued compliance. Once the pressure drop is seen, the 

system could very well be out of compliance.

The operating limit for opacity is no visual emissions. Method 22 is the appropriate method for 

application because it is a yes/no reading and does not give a quantifiable reading like Method 9.

It should be noted that VE is merely a tool to gauge whether the system is working properly and 

the remedy for a VE failure is to take corrective action. If no VE is observed, then no action is 

warranted.

Comment 10: Commenters 0244 and 0247 opposed the 15-minute Method 22 observation 

requirement. The commenters noted that Section 11.4.2 of Method 22 specifies a 6-minute 

observation, while proposed 40 CFR 63.8620(e)(l) requires a 15-minute observation. Commenter 

0247 stated there is no explanation or justification provided for the difference and argued that 

a 15-minute observation period is arbitrary and capricious.

Commenter 0247 stated that the proposed 15-minute VE observation period would require them

to hire more than one full time employee whose only job would be to perform VE observations. 

Major sources in this subcategory have one or more than one manufacturing building, several 

hundred yards in length or width, or both, multiple factories or other configurations, and multiple 

emission points all on one contiguous property. The commenter claimed that EPA either did not 

understand or ignored these proportions because its economic impact analysis is inaccurate. 

Compliance with this VE proposal would take all day, every day. The annual estimated cost for 

the proposed VE measurements of $2,98427 is unrealistic. Industry representatives estimate the 

actual cost with benefits to comply with this proposal would be 15-30 times more than this 

estimate. Even a reduction in observation time to 6 minutes, or the weekly observation frequency 

that is proposed compliant VE observations,28 are more than is necessary to assure NESHAP 

compliance.

Commenters 0244 and 0247 recommended daily magnahelic gauging of pressure drop should be 

added as an alternative to VE observations. If EPA keeps the VE requirements, then the 

commenter recommended 6-minute Method 22 observations as they will yield the same 

compliance determinations as the 15 minute observations at lower cost. The commenter further 

proposed that NESHAP VE observations be required to satisfy state permit requirements and not 

a separate NESHAP-imposed requirement. Requiring VE for longer than 6 minutes serves no 

lawful purpose, is unduly burdensome, and is unnecessary. If finalized as proposed, Commenter 

0247 stated this proposal would be arbitrary and capricious. 

 27 Docket Item No. EPA-HQ-OAR-2013-0290-0229, at Tables 1 and 4 (Nov. 6, 2014). 28 40 CFR 63.8620(e)(2) and (3), 79 FR 75699 (col. 3) (Dec. 18, 2014)
90

Response 10: Method 22 does not specify 6 minute observations. It leaves the observation 

period up to the subpart. According to the Method, no observation may be less than 6 minutes 

and observers must take a break after 15-20 minutes. Many subparts designate 1 to 2 hours of 

observations. A 15-minute period allows for only one observer and is consistent with the 15-

minute requirement for collecting the CMS data. In addition the cost for daily VE is for the kiln 

stack only and thus should not be more than 15 minutes per day per stack. Unless there are 32 

kiln stacks per contiguous source in operation in any one 8-hour shift, the need for a full time 

reader of VE is not substantiated.

Comment 11: Commenter 0244 noted that Table 2, Item 5.c requires the kiln operating 

temperature to be maintained at or below the average temperature established during the 

dioxin/furan performance test. The commenter stated this condition seems contrary to Item 4 of 

this table, which states that kiln temperature should be at or above the average temperature 

established during the dioxin/furan performance test. Commenter 0244 requested EPA confirm 

how this operating limit will be applied.

Response 11: The EPA agrees with the commenter that there is a discrepancy. Item 5.c should 

have stated that sources must maintain the operating temperature at or “above” the average 

temperature established during the D/F performance test. Regardless, as noted in our response to 

the following comment, we are revising the operating limit for promulgation to require sources 

to maintain the stack temperature and not the kiln temperature, at or below the highest 4-hour 

average stack temperature established during the D/F performance test. 

Comment 12: Commenters 0244 and 0247 expressed concern about the kiln temperature 

requirements in Table 2, item 5.c. and Table 7, 5.a.iii. Commenter 0244 asserted that the 

operating temperature limit needs to be established at a level that affords some operational 

flexibility29 and requested the temperature limitation be revised to either: (1) the peak kiln 

temperature must be maintained above 2000 degrees F; or (2) set at least 100 degrees F below 

the average temperature achieved in the performance test. Noting that a tunnel kiln is comprised 

of many different temperature zones across the ramp-up, soak, and rapid cool temperature profile 

of the tunnel kiln, the commenter also requested that EPA specify exactly what temperature is to 

be used for monitoring for the operating limit.

Commenter 0247 stated that there is no justification for a CPMS-specific temperature 

measurement requirement so long as the major source facility is capable of demonstrating 

through production monitoring equipment that the relevant temperature is above 450 degrees C 

for kilns and below 200 degrees C for tile dryers. The commenter stated EPA’s CPMS proposal 

is unnecessary, unduly burdensome, does not result in incremental protection of air quality, and 

would be arbitrary and capricious. 

Commenter 0247 also challenged EPA’s proposal to require D/F CPMS as proposed in 40 CFR 

63.8570. The commenter argued the EPA has no technical foundation for D/F CPMS because 

there are no scientifically valid D/F emissions information for this subcategory and no available 

D/F-specific CPMS technology. 

 29 Assuming EPA’s intent is to limit the minimum operating temperature of a kiln to at or above the average 

temperature established during the dioxin/furan performance test.
91

The commenter requested clarification that CPMS applies only to the air pollution control 

equipment employed during NESHAP compliance performance testing and that CPMS does not 

apply to equipment or air pollutants not subject to this NESHAP. The commenter also stated

EPA failed to provide the public with adequate detail regarding the extent of the proposed 

CPMS.30 EPA’s failure unlawfully precludes the public’s opportunity to comment fully. It would 

be arbitrary and capricious for EPA to finalize detailed CPMS regulations without proposing 

such details and providing an opportunity for the public to comment. 

Federal laws and Executive Orders 12866 and 13563 require EPA to consider the requirements 

of other EPA programs in establishing NESHAP monitoring system requirements to assure a 

lack of duplication and overlap. Those facilities in this industry subject to Part 70 or 71 Title V 

permitting must comply with CAM requirements, which are extensive. EPA failed to consider 

CAM or to explain why compliance with CAM requirements is not legally and technically 

adequate to demonstrate continuous compliance with a final NESHAP. The commenter argued 

there is no justification for a CPMS program where, as here, other already-applicable 

requirements achieve the same outcome.

Response 12: We agree with the commenter that redoing performance tests based on variations 

in kiln temperatures is not an efficient use of resources when the small kiln temperature 

variations most likely do not have an effect on the dioxin emissions level. The better parameter 

for demonstrating compliance would be the stack temperature. Dioxins and Furans are known to 

form in post-combustion gases in temperature ranges of 200 to 400 degrees C (392 to 752 

degrees F).

31 Assuring that the maximum stack temperature recorded during the compliance test 

is never exceeded will assure that the dioxin limit is continuously met. Therefore, we are revising 

the requirement by basing the performance parameter on the stack temperature and not the kiln 

temperature. Thus, the new requirements in Table 2 to Subpart KKKKK of Part 63--Operating 

Limits, and Table 4 to Subpart KKKKK of Part 63--Requirements for Performance Tests, will 

read as follows: 

You must continuously measure the stack temperature and determine and record the 

temperature values for the three test runs. The highest 4-hour average stack temperature 

of the three test runs establishes your maximum site-specific stack temperature operating 

limit.

The EPA disagrees with the comment that “EPA has no technical foundation for proposing or 

imposing CPMS for D/F unless and until scientifically valid D/F emissions information is 

presented that demonstrates significant D/F emissions from this subcategory.” Valid D/F 

emissions were presented in the ICR and represented levels that a MACT limit was set. Because 

the performance tests are required, a CPMS is needed to demonstrate the system is working in a 

similar manner that demonstrated compliance with the D/F limit. If an owner or operator have a 

different parameter they use to monitor the system and emission, he/she can submit an 

 30 79 FR 75695 and 75698 (Dec. 18, 2014)(proposed to be codified at 40 CFR 63.8575 and 63.8600). 31 Observations on the Effects of Process Parameters on Dioxin/Furan Yield in Municipal Waste and Coal Systems,

Gullett, Brian K. and Raghunathan K., Chemosphere, Vol. 34 Nos. 5-7, p. 1027, 1997.
92

application to use of an alternative monitoring procedure by following the General Provisions 

section 63.8(f)(4).

Comment 13: Commenter 0244 requested that EPA revise Table 2, Item 8 and Table 7, Item 8.a 

to change the frequency of leak inspections for system ductwork and control device equipment. 

The proposed requirement to conduct “weekly” visual inspections is more frequent than 

necessary for compliance assurance. A weekly inspection is unnecessarily burdensome for 

equipment that is not prone to leaks, where any leaks would develop slowly, and even if a leak at 

a water curtain spray booth were to occur, it would not result in added emissions to the 

atmosphere or a violation of an emission limitation. The commenter requested the frequency of 

the proposed inspection be revised to no more than once/year.

Response 13: This visual inspection is to ensure the process and control device is working 

properly and there are no glaring issues with the process. It is common practice to have a walk 

through before shift change in many industry sectors. This visual check should be easily 

incorporated in daily operations.

Comment 14: Commenter 0244 stated that more information is needed on how redoing 

performance tests to set new operating limits can be completed without violating the 

MACT/permit (see Table 7: Item 5.a.iii). For instance, if 6 months after the initial performance 

test, the source operator wants to make process improvements that may decrease the peak 

operating temperature of the kiln by 100 degrees F from that measured during the first 

performance, the operator must redo the performance test at the lower temperature. It can take 

several weeks to optimize a new throughput cycle, and while this is being done, the kiln will be 

in constant noncompliance (below the average temperature measured during the previous 

performance test) as it migrates to the new process curve. The commenter asked how this 

situation should be handled. The commenter requested that an appropriate temperature limit is to 

maintain the peak kiln temperature above 2000 degrees F as previously discussed, for continuous 

compliance demonstration. Alternatively, the commenter requested some type of temporary 

waiver be available for a source so that when kiln cycle changes are implemented they do not 

result in non-compliance with the rule.

Response 14: We have revised the requirement for continuous compliance in Table 7, item 

5.a.iii. so that the owner or operator must maintain stack temperatures, and not kiln temperatures, 

to assure continuous compliance with the D/F limit. We believe this new requirement will assure 

D/F does not reform and is a better parameter for which to assure compliance. The revised 

requirement reads as follows:

Collecting the stack temperature data according to §63.8600(a); and maintaining the stack 

temperature at or below the highest stack temperature established during the dioxin/furan 

performance test in which compliance was demonstrated.

Please refer to Comment 12, Response 12 for more background on this revision.

Comment 15: Commenter 0244 stated that the two conditions in Table 7, items 12.a.ii and iii for 

making an alternative fuel notification within 48 hours of a declaration of a natural gas 

curtailment event and submitting a written report of alternative fuel use within 10 days of 
93

terminating alternative fuel use are inappropriate and unnecessary. Alternative fuel use during 

periods of natural gas curtailment is already an approved operating scenario in air permits. These 

instances are already required to be addressed in the facility’s semi-annual monitoring report, 

even though they technically do not constitute a permit deviation. This is sufficient notification 

for this type of activity, and special 48-hour notification and 10-day reporting for non-deviation 

activity serves no useful purpose. Commenter 0244 requested these two requirements be 

removed and that EPA also confirm that similar requirements do not apply to tunnel kilns.

Response 15: The EPA disagrees with the commenter’s request to remove the 48-hour 

notification of alternative fuel use and the 10-working day report of terminating alternative fuel 

use. The commenter argues that the notification and report are unnecessary and that using an 

alternative fuel is not considered a deviation. However, failure to give EPA timely notice that the 

facility is no longer complying with the work practice standard requiring natural gas usage would 

be considered a violation of the standard. Providing notice to EPA in a semiannual monitoring 

report could mean that the facility is operating as long as 6 months in a manner inconsistent with 

the work practice standard. Timely notice is essential to ensure that the facility remains in 

compliance with the standard. We believe that a 48-hour notification of alternative fuel use and 

10-working day report of terminating alternative fuel use provide timely notice to EPA without 

imposing an undue burden on the facility. Regarding the commenter’s other request that EPA 

also confirm that similar requirements do not apply to tunnel kilns, the regulatory language 

clearly references the periodic kiln work practice standard in Table 3 to the subpart, so no further 

clarification is necessary.

Comment 16: Commenter 0244 requested clarification concerning the impact of power outages 

on compliance. The commenter noted that it is not uncommon for power outages to affect a 

facility, and so affect tunnel kiln operation by shutting down the natural gas fuel train. It can take 

a few hours to get kilns relit and operating. As a result, the kiln temperature can drop a few 

hundred degrees in response to the outage and may fall below the operating limit for 

temperature. The commenter asked whether such a power outage event will be classified as a 

noncompliance event or a deviation. The commenter stated that issues with electrical grid 

reliability are outside their company’s control.

Response 16: A power outage that results in “sudden, infrequent, not reasonably preventable

failures of emissions control, process or monitoring equipment,” such as a tunnel kiln, would, by 

definition, fall into the category of a malfunction (40 CFR 63.2). In the event that a source fails 

to comply with the applicable CAA section 112 standards as a result of a malfunction event, the 

EPA would 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.
94

14.0 Compliance Dates

Comment 1: Commenters 0246 and 0247 supported the compliance deadlines proposed in 40 

CFR 63.8545, 79 FR 75694 (col. 2), which they stated are consistent with CAA section 

112(i)(3), and 40 CFR 63.6(c)(5) and 63.6(b)(7).

Response 1: The EPA appreciates the commenters’ support for the compliance deadlines.
95

15.0 Recordkeeping and Reporting

Comment 1: Commenter 0244 requested EPA change the performance test notification in 40 

CFR 63.8630(d) from 60 to 30 days. The commenter asserted that 30 days is sufficient for 

notification for a performance test. It is common for state agencies to only require 30-day notice 

for emissions testing, and this condition should be consistent with state requirements. The State 

of Wisconsin only requires a 20-day notification of intent to test [NR439.07(2)].

Commenter 0244 also requested that the performance test reporting and Notification of 

Compliance Status submittals in 40 CFR 63.8630(e)(1) and 40 CFR 63.8635(i) be changed from 

60 to 120 days. The commenter asserted that 120 days is needed for reporting due to the 

magnitude and complexity of the testing and analysis being required, and to account for 

documented ERT tool use issues. The commenter contended that 60 days is an unreasonably 

short amount of time to report results, as acknowledged by EPA in Section V of the September 9, 

2014 memorandum from EPA to the docket titled “Use of the Upper Prediction Limit for 

Calculating MACT Floors,” which specifically refers to the collection of HAP emissions data as 

a “...time- and resource-intensive effort, as emissions tests can take more than a week to perform, 

analyses of samples from the tests can take more than a month, preparation of test reports 

typically takes several months, and costs range up to $40,000 per test per pollutant.”

Response 1: State and local agencies have varying requirements depending on the permit. The 

60 days required for the performance test notification and notification of compliance status is the 

federal requirement for part 63 in the General Provisions when states do not have delegation. In 

40 CFR 63.9(i) of the General Provisions, the Administrator can be petitioned for an adjustment 

to the notification deadline and can approve or deny the request for an adjustment.

Comment 2: Commenter 0244 requested EPA delete the alternative fuel notification in 40 CFR 

63.8630(g) and the alternative fuel use report in 40 CFR 63.8635(h). The requirements to submit 

a notification of alternative fuel use within 48 hours of a period of natural gas curtailment and 

submit a written report of alternative fuel use within 10 days of terminating alternative fuel use 

are unnecessary. Alternative fuel use during such periods is already an approved operating 

scenario in air permits. These instances are already required to be addressed in the facility’s 

semi-annual monitoring report, even though they technically do not constitute a permit deviation. 

This is sufficient notification for this type of activity, and special 48-hour notification and 10-day 

reporting for non-deviation activity serves no useful purpose and is an undue burden.

Response 2: The EPA disagrees with the commenter’s request to remove the 48-hour 

notification of alternative fuel use and the 10-working day report of terminating alternative fuel 

use. The commenter argues that the notification and report are unnecessary and that using an 

alternative fuel is not considered a deviation. However, failure to give EPA timely notice that the 

facility is no longer complying with the work practice standard requiring natural gas usage would 

be considered a violation of the standard. Providing notice to EPA in a semiannual monitoring 

report could mean that the facility is operating as long as 6 months in a manner inconsistent with 

the work practice standard. Timely notice is essential to ensure that the facility remains in 

compliance with the standard. We believe that a 48-hour notification of alternative fuel use and 

10-working day report of terminating alternative fuel use provide timely notice to EPA without 

imposing an undue burden on the facility.
96

Comment 3: Commenter 0244 requested EPA revise the provisions in 40 CFR 63.8640(c)(3) to 

require all kiln throughput data be reported on a “ton greenware processed” basis, rather than on 

a “fired-product weight” basis. ICR testing production data were greenware-based, not fired 

product-based. This record should be based on greenware weight since this is consistent with 

how process data was reported to EPA for the ICR.

Response 3: Because the recordkeeping requirement in 40 CFR 63.8640(c)(3) is intended to 

apply to both sanitaryware and ceramic tile kilns, the EPA cannot grant the commenter’s request 

to change “fired-product weight” to “ton greenware processed.” As noted previously in this 

document, while the production rates reported by the sanitaryware company in their section 114 

survey responses are in terms of “greenware fired” into the kiln, the production rates reported by 

the ceramic tile companies are in terms of “fired product” coming out of the kiln (as requested in 

the section 114 survey). However, we have changed the term “fired-product weight” in 40 CFR 

63.8640(c)(3) to the more generic term “ton throughput processed” to eliminate any 

inconsistency with how the commenter’s company reported their production rates.
97

16.0 Submission of Emission Test Results (ERT)

Comment 1: Commenter 0247 opposed the proposed use of EPA’s ERT for reporting data from 

the ceramic tile subcategory. According to the commenter, EPA’s ERT software is a 

“bureaucratic disaster, acknowledged as such by EPA and the regulated community.” The 

commenter noted that the March 2010 ICR required the ceramic tile industry to submit stack 

testing information to EPA through the ERT. The industry has no objection to the use of 

electronic submissions that are usable and quality assured. However, the commenter’s 

consultants, who had prior experience with the ERT, experienced problems entering data into 

ERT. Correctly entered data was randomly changed or deleted by the software and data was 

inaccurately converted by the ERT from one draft to the next. Breakdowns and errors in the 

software were observed and the ultimately EPA went back to the stack testing reports themselves 

for reliable data, and maybe to verify and correct ERT-reported data. Under these circumstances, 

the commenter objected to EPA’s proposal to continue to require the industry to submit future 

data using the ERT. The commenter proposed that EPA delete the requirement to submit data 

using the ERT and instead only require the underlying stack testing report to be submitted.

Response 1: The EPA disagrees with the commenter that the EPA delete the requirement to 

submit data using the ERT. The ERT has continually improved over the past 5 years based on 

comments from users. It is currently required in over two dozen federal rules and the EPA has

currently proposed to require its use in the majority of NSPS rules. States are well aware of the 

ERT and some states are requiring its use for state testing as well as federal testing. Some states 

allow ERT reports instead of hard copies. The ERT equations have be validated and if the data is 

entered correctly, the final results are accurate and reliable. Over 500 test reports have been 

submitted via ERT. The ERT has a completeness check to assist users in completing the ERT 

file. Users will still need to review their data and make sure the ERT data was entered correctly.

The ERT is designed to streamline, standardize, and incorporate quality assurance and quality 

control information for all the test reports and facilitate their submittal to the EPA. The ERT will 

also make the process of developing emissions factors much more transparent. All the steps 

taken and data used to develop emissions factors will be much clearer with our new system. We 

understand that there will be little or no reduction in the effort needed to produce the test report 

initially, but as users gain expertise with the system and it improves over time, the time, 

resources, and consistency for review and evaluation will be improved.
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17.0 Definitions

Comment 1: Commenter 0244 stated that the definition for “Kiln design capacity” in 40 CFR 

63.8665 should be revised to state “maximum amount of greenware clay ceramics.”

Response 1: The EPA cannot grant the commenter’s request, because this definition is intended 

to apply to both sanitaryware and ceramic tile. As noted previously in this document, while the 

production rates reported by the sanitaryware company in their section 114 survey responses are 

in terms of “greenware fired” into the kiln, the production rates reported by the ceramic tile 

companies are in terms of “fired product” coming out of the kiln (as requested in the section 114 

survey). Consequently, we will continue using the more generic term “clay ceramics” in this 

definition.

Comment 2: Commenter 0244 recommended the definition for “Particulate matter (PM)” in 40 

CFR 63.8665 be revised to state “...emission of filterable PM...” The commenter stated this 

change would confirm that Reference Method 5 front-half applies and would be consistent with 

the wording used in Section II of the November 6, 2014 memorandum from RTI International to 

EPA titled “MACT Floor Analysis for Clay Ceramics.”

Response 2: The EPA agrees with the commenter’s request and has revised the definition of 

“Particulate matter (PM)” in 40 CFR 8655 as suggested. In response to another comment (in 

section 7.2 of this document), the EPA has also removed mention of Hg from the definition, 

since Hg is being regulated separately, and PM is intended to serve as a surrogate for non-Hg 

metal HAP.
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18.0 Costs and Impacts

Comment 1: Commenter 0244 argued that EPA has significantly underestimated emissions 

testing costs in preamble section I.A.2, Table 2 ($102,000, which is $24,900 annualized cost). 

The commenter’s actual cost for emissions testing in 2010 per EPA’s ICR exceeded $320,000 at 

their three facilities. As this proposed rule is currently drafted, the scope for performance testing 

will include more stacks than completed under the ICR, and when testing is required in 2019, 

costs will likely exceed $400,000, and potentially much higher if performance test adjustments 

are needed to meet variable process conditions, including market demand. This is significantly 

higher than EPA’s estimate, and is based on actual costs incurred in 2010 at the commenter’s 

three facilities. The commenter stated the EPA should revise the cost estimate. Commenter 0244 

argued that the costs in Table 5 of the November 6, 2014 memorandum from RTI International 

(Holloway) to EPA (Telander) titled “Monitoring and Testing Requirements and Costs for the 

Clay Ceramics NESHAP” are also underestimated and Table 5 needs to be redone with real cost 

data to make this a valid assessment.

Response 1: Testing costs for both BSCP and Clay Ceramics have been revised to include costs 

for audits ($1000), ERT ($2000) and Compliance and Emissions Data Reporting Interface 

(CEDRI) ($2000), based on information provided by Commenter EPA-HQ-OAR-2013-0291-

0539 on the proposed BSCP rule. The inclusion of these costs (50 percent of which was assumed 

to apply to each individual test) is estimated to increase testing costs close to Commenter 0244’s 

estimate. We are unable to use the commenter’s total estimates, because our testing cost 

estimates are developed on a more specific basis, based on the number of sources tested, the test 

methods used, and costs for equipment rental, travel, testing, laboratory analysis, test report, and 

the additional three items noted above.
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19.0 Statutory and Executive Order reviews

Comment 1: Commenter 0247 argued that the proposed NESHAP is invalid because EPA failed 

to comply with the Regulatory Flexibility Act (RFA) and SBREFA and that ignoring small 

business interests and impacts in the ceramic tile manufacturing industry violated the RFA and 

the SBREFA. The cost of major source compliance with the proposed NESHAP would be an 

economic barrier to the expansion of small businesses and will provide non-market-based 

economic advantages to foreign producers importing their products into the U.S. Financing of 

capital projects will be more expensive and difficult and small businesses will bear a 

disproportionate burden. The EPA’s economic analysis was based on three existing major 

sources in this subcategory and is flawed.

The commenter noted that the RFA and SBREFA require the EPA to consider the impact of a 

proposed regulation on small business and to adjust its regulatory approach when necessary. On 

a per capita basis, the commenter argued, the vast majority of the ceramic tile industry in the 

United States is comprised of small businesses that fall under the small business size standards of 

the U.S. Small Business Administration, 13 CFR 121.201 (2014). Together, they make up a 

“substantial” portion of the industry; however, the EPA recognized 12 small businesses in this 

subcategory in 2003 for the vacated 2003 NESHAP for this subcategory,32 but ignored economic 

impacts on small business for this rulemaking. The commenter stated that the industry has 

changed markedly since 2003 and hence the 2003 analysis is inadequate support for this 

rulemaking. According to the commenter, EPA’s failure to accurately evaluate the industry 

deprived small ceramic tile manufacturing businesses of their RFA and SBREFA rights, 

including their right to a Small Business Advocacy Review (SBAR) panel. 

The commenter argued that RFA and SBREFA also require EPA to consider whether the 

possible future sources subject to the NESHAP might be small businesses. The commenter stated 

that EPA cannot lawfully promulgate a final NESHAP unless it considers the needs of small 

business by following the requirements of the RFA and the SBREFA.

Response 1: The EPA disagrees with the commenter that we failed to comply with the RFA and 

SBREFA. Under the RFA, the EPA is required to determine whether the NESHAP will have a 

significant economic impact on a substantial number of small entities, in which case the EPA 

would have to take action under the RFA and SBREFA to minimize the impacts. Because there 

are currently no major source ceramic tile manufacturing facilities that would be subject to the 

NESHAP, there is no economic impact to evaluate, and no action to be taken under the RFA and 

SBREFA.

Comment 2: Commenter 0247 argued the proposed NESHAP was issued in violation of the 

Information Quality Act (IQA) and the Paperwork Reduction Act (PRA), as amended. According 

to the commenter, there is no evidence the EPA considered and discharged its IQA or PRA 

obligations in the development of the proposed NESHAP. The commenter alleged the March 

2010 ICR violated the PRA because it required stack testing using a method “known by EPA to 

not generate scientifically valid data useable for purposes of development of the NESHAP.” 

 32 Economic Analysis of the Clay Ceramics Manufacturing NESHAP: Final Rule, EPA-452/R-03-007, at pages 5-1 

and 5-2, and Table A, EPA Office of Air Quality Planning and Standards (Feb. 2003).
101

The commenter noted the PRA allows the Office of Management and Budget (OMB) to approve 

an information collection request only if it has first determined the data collection is necessary 

and has “practical utility.” See, e.g., 44 U.S.C. 3508 (2014). It is EPA’s legal burden to 

demonstrate to OMB that the data is seeks to collect through an ICR meets this burden. 5 CFR 

1320.9 (2014). According to OMB’s implementing regulations, the term “practical utility”

means: “the actual, not merely the theoretical or potential, usefulness of information to or for an 

agency, taking into account its accuracy, validity, adequacy, and reliability, and the agency’s 

ability to process the information it collects (or a person’s ability to receive and process that 

which is disclosed, in the case of a third-party or public disclosure) in a useful and timely 

fashion.” 5 CFR 1320.3(1) (2014). The commenter alleged that the EPA knew at the time it 

sought OMB approval for the March 2010 ICR that Method 23 was seriously flawed, that EPA 

had plans to rewrite Method 23 to address those flaws, and that Method 23 did not generate 

scientifically valid data. The commenter further alleged the EPA failed to inform OMB of these 

problems, preventing OMB from making an informed decision. 

Response 2: The EPA disagrees with this comment. First, it should be noted that because the 

section 114 survey of the clay ceramics industry was submitted to less than nine sources, formal 

OMB approval of the ICR was not necessary. Second, we refer to our response in section 5.4 of 

this document refuting the commenter’s argument that Method 23 does not generate valid D/F 

data for the ceramic tile industry sector. Because these D/F data are valid, we conclude that no 

violation of the IQA and PRA has occurred. 

Comment 3: Commenter 0247 argued that the proposed D/F standard fails to satisfy the 

requirements of the National Technology Transfer and Advancement Act (NTTAA). EPA states 

that it has complied with section 12(d) of the NTTAA by accepting alternative consensus stack 

testing methods for all regulated HAP, except D/F and Method 23. The docket reflects that EPA 

evaluated an alternative method to Method 23: EN 1948-3 (1996) (European Committee for 

Standardization)--Determination of the Mass Concentration of PCDD’S/PCDF’S Part 3: 

Identification and Quantification.33 EPA was required to consider the limitations and 

inadequacies of Method 23 and provide a reasoned explanation for not adopting this voluntary 

standard as equal to, or as an improvement to, Method 23. EPA failed to do so. EPA is now 

obligated to correct its failure through the re-proposal process.

Response 3: The EPA disagrees with the commenter that we failed to provide a reasoned 

explanation for not adopting EN 1948-3 as an alternative to EPA Method 23. As noted in 

Attachment 1 to the memorandum cited by the commenter, which was used as support for the 

EPA’s NTTAA review, EN 1948-3 provides additional sampling options other than what is 

acceptable in EPA Method 23. Consequently, it was concluded that this method would not be 

practical to use as an alternative to EPA Method 23. We conclude that the EPA’s NTTAA

review is sound, and no re-proposal is necessary.

 33 Voluntary Consensus Standard Results for 40 CFR Part 63, Subpart KKKKK National Emission Standards for 

Hazardous Air Pollutants for Clay Ceramics Manufacturing, at page 10 (June 30, 2014). Docket Item No. EPA-HQOAR-2013-0290-0215.
102

20.0 General Comments

Comment 1: Commenter 0246 supported, and incorporated by reference, the comments and 

positions prepared and submitted by the Tile Council of North America (TCNA). Commenter 

0246 agreed with the TCNA’s conclusion that the proposed NESHAP would, if finalized as 

proposed, be arbitrary and capricious.

Response 1: Commenter 0246’s support for, and incorporation by reference of, the comments 

from TCNA (Commenter 0247) are duly noted.
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21.0 Other Comments

Comment 1: Commenter 0247 challenged EPA’s proposal to require the installation of an 

activated carbon injection (ACI) system and the proposed alternative workplace production 

limitations. The commenter stated both requirements are arbitrary and capricious. The 

commenter noted that EPA proposed the installation of an ACI system as an option to achieve 

compliance with the proposed D/F and Hg emission limits (79 FR 75694 (col. 2); proposed to be 

codified at 40 CFR 63.8560(a)). In practical terms, ACI would be mandatory, not optional, 

because EPA proposes no other options to meet proposed D/F and Hg emission limits and the 

proposed no-ACI option could effectively reduce production to the point of shutting down a 

major source. The commenter contended the regulatory approach taken by EPA in proposing 

ACI is unlawful, and the EPA-anticipated abatement efficiency of ACI is erroneous.

The commenter also argued that ACI is unlawfully proposed as part of EPA’s MACT floor 

analysis. CAA Section 112(d)(3)(B) requires the MACT floor to reflect the degree of reduction 

in HAP emissions “achieved in practice” by the “five best performing sources” in the 

subcategory proposed to be regulated. EPA is aware ACI is not, and has never been used in the 

ceramic tile manufacturing industry.34 Therefore, ACI is not by definition eligible for 

consideration in a MACT floor analysis.

The commenter stated that ACI was eligible for consideration in a beyond-the-floor analysis, but 

noted that EPA did not perform a beyond-the-floor analysis on ACI. Had EPA performed a 

beyond-the-floor analysis on ACI, the commenter stated ACI would not have been proposed

since the cost of further D/F and Hg emissions reductions would be trillions of dollars per ton of 

pollutant abated. The commenter stated it would also be arbitrary and capricious for the EPA to 

propose ACI based on a beyond-the-floor analysis.

Response 1: The EPA disagrees with the commenter that we are requiring the installation of an 

ACI system. It is up to each source to determine which control methodology to employ to 

comply with the emission limits. ACI was not part of any MACT floor analysis, which would be 

inappropriate, but simply a means of estimating the potential cost and environmental impacts of 

MACT floor (and beyond-the-floor) options.

Comment 2: Commenter 0247 challenged the use of ACI and argued the EPA should not 

include ACI in the final rule because the abatement efficiency is technically inaccurate and there 

is a lack of independent foundation for requiring ACI. The reasons provided by the commenter 

supporting their statements included:

1. The commenter noted the EPA referenced the use of ACI for abatement of Hg in waste 

incinerators, boilers and cement kilns and argued the EPA failed to consider the 

following differences between ceramic kilns and these other industries:

o In these other industries, Hg is in gaseous phase when activated carbon is 

injected; ceramic kilns have very little organic carbon. The EPA should have 

 34 Docket Item No. EPA-HQ-OAR-2013-0290-0227, Methodology and Assumptions Used to Estimate Model Costs 

and Impacts of Clay Ceramics Air Pollution Control Devices, at page 6 (Nov. 6, 2014) (hereinafter “EPA Docket no. 

227”)
104

compared the gaseous state of the Hg in the comparative industries with the 

physicochemical state of the Hg in the ball clay matrix.

o The EPA did not investigate the use of ACI for spray dryers or tile dryers. There 

is no possible analogy (and none offered in the docket) between ACI usage in 

other industries and control of emissions from a spray dryer or tile press dryer in 

the ceramic tile manufacturing industry.

2. It would be arbitrary and capricious to require ACI for ceramic tile kilns, when the 

particulate emissions from spray dryers are already controlled, and ACI would be 

duplicative.

3. An ACI vendor contacted by the EPA admitted ACI had not been used in the ceramic tile 

manufacturing industry and indicated his only experience was with gaseous Hg

associated with medical waste combustors. The docket does not show that EPA 

independently verified the vendor’s mostly inapplicable opinions and the EPA failed to 

ask the vendor or any independent source if ACI had been used in the context of Hg in an 

encapsulated solid matrix. 

4. Although the EPA proposed ACI as a control strategy for D/F, one vendor offered no 

opinion on ACI’s efficacy for D/F and another vendor never responded.

5. Although the EPA’s contractor stated it “would be prudent to explore this technology”

(see EPA Docket no. 227, at page 6 (Nov. 6, 2014)) and did not recommend ACI for the 

control of D/F or Hg emissions from this subcategory, the EPA never explored this 

technology further in the development of the proposed NESHAP. 

6. The EPA previously recognized that pore size is essential for ACI to be effective (see 

Choosing an Adsorption System for VOC: Carbon, Zeolite, or Polymers?, EPA 456/F-99-

004 (May 1999). EPA cited gaseous adsorption and outline physico-chemical parameters 

for gas adsorption; e.g., isotherms, vapor pressure, mass transfer, etc. For ACI to be 

technically effective, the pollutant must be in a physicochemical form capable to be 

sorbed by the carbon. The commenter argued that Hg and D/F encapsulated in a solid ball 

clay matrix are not available to be sorbed and therefore, ACI would be ineffective for 

ceramic tile kilns. The EPA’s contractor noted a decrease in D/F emissions associated 

with the application of ACI to a ceramic tile kiln in EPA Docket no. 227 at Tables F-8 

and F-10 (Nov. 6, 2014); however, the commenter stated the EPA had provided no 

mathematical or other technical foundation or support for this statement.

Response 2: As noted in our previous response, the EPA is not requiring the use of ACI to 

comply with the emission limits. Each source would determine how it plans to comply. 

Regarding the commenter’s technical comments, the commenter has provided no evidence that 

Hg and D/F would be completely encapsulated in a ball clay matrix and thus not available for 

control in the gaseous phase, either for kilns or dryers. In addition, we have stated previously that 

there is ample evidence in other industries, and in similar process units (Portland cement kilns), 

that ACI is an effective means of reducing Hg and D/F emissions. The commenter has provided 

no evidence that the technology would be ineffective for the clay ceramics industry, only 

conjecture. Without any actual evidence to the contrary, we conclude that ACI is an appropriate 

technology for controlling Hg and D/F from the clay ceramics industry and that its inclusion in 

our cost and impacts analyses was entirely appropriate.
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Comment 3: Commenter 0247 requested that EPA confirm sources may use whatever means 

and methods they deem necessary to demonstrate and achieve compliance with NESHAP 

emission limitations, including those for Hg and D/F. EPA’s goal should be achieving NESHAP 

compliance and not dictating an individual facility’s approach. EPA stated in the preamble that: 

“its proposal was intended to allow a regulated source to choose any control technology or 

technique to meet emissions limits, rather than requiring each unit to use a prescribed control 

method that may not be appropriate in each case.” (79 FR 75656 (col. 1)).

The commenter recommended the final NESHAP clarify that each major source in this 

subcategory can decide to install ACI, another type of pollution control equipment or decide not 

to install pollution control equipment. Procedures for monitoring, recordkeeping and reporting 

for control equipment other than ACI would be developed by the source and incorporated into its 

OM&M plan, which would be subject to review by EPA or the delegated-state authority.

Response 3: The EPA agrees with the commenter that industry may use whatever means and 

methods they deem necessary to achieve compliance with the emission limits in the NESHAP. 

As noted in our previous responses in this section, it was never our intention to require sources to 

use ACI to comply with the emission limits for Hg and D/F. Regarding the commenter’s request 

that the final NESHAP reflect that each major source in this subcategory has the right to choose 

to install or not install pollution control equipment other than ACI, the NESHAP already 

includes such provisions. While the NESHAP includes monitoring provisions for ACI, sources 

also have the option to use alternative monitoring procedures under 40 CFR 63.8595(h). These 

sources would also maintain records for approved alternative monitoring under 40 CFR 

63.8640(c)(3). Compliance reports prepared and submitted under 40 CFR 63.8635 would contain 

information pertinent to these alternative monitoring procedures, and the OM&M plan developed 

under 63.8575 would include the alternative control device and monitoring procedures.

Comment 4: Commenter 0247 agreed with EPA that routine maintenance, including routine 

maintenance of air pollution control devices, is essential for air quality and the health and safety 

of employees and the surrounding community. It is essential for successful operation of a 

ceramic tile manufacturing facility as well. However, the commenter challenged EPA’s proposed 

routine control device maintenance approach (79 FR 75694 (col. 3)-75695 (col. 1); proposed to 

be codified at 40 CFR 63.8570(b)). The commenter contended that the proposed pre-approval 

process frustrates good air pollution control practices and forces major sources to choose 

between: (1) violating the NESHAP and legal enforcement for not waiting for government 

approval, or (2) not being able to lawfully abate unacceptable and unnecessary environmental, 

health and safety risks in a timely manner. The commenter recommended EPA delete the 

proposed EPA pre-approval process. The commenter was concerned that government staff will 

not be assigned in a timely manner, and that there will be little priority assigned to this type of 

review. The commenter was also concerned that those government staff that potentially would be 

assigned to the proposed pre-approval process are unlikely to have the requisite background for 

the necessary decision making. Decisions will be delayed and be unpredictable. Waiting to 

perform necessary routine maintenance is a burden on the regulated community. EPA provided

no explanation why pre-approval is necessary and potentially defeats the goal of assuring routine 

maintenance occurs in a timely manner.
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Commenter 0247 recommended 40 CFR 63.8570(d)(1) and 40 CFR 63.8570(d)(3) be deleted (79 

FR 75695 (col. 1)). The commenter supported proposed 40 CFR 63.8570(d)(2) (79 FR 75695 

(col. 1)), as a rewritten compliance recordkeeping requirement. An exceedence of the four 

percent annual limitation would be considered a deviation under a revised 40 CFR 63.8620(d). 

The commenter also challenged proposed 40 CFR 63.8570(d)(4) and (d)(5) (79 FR 75695 (col. 

1)), because they do nothing more than qualitatively emphasize behaviors already strongly 

encouraged by the proposed NESHAP. Their qualitative nature precludes advance notice and 

understanding of unlawful or prohibited conduct, invites uncertainty in enforcement and in the 

assertion of defenses to enforcement, and are unnecessary.

Alternatively, Commenter 0247 suggested EPA could modify proposed 40 CFR 63.8570(d)(1) to 

state that failure by the Administrator (or a delegated state agency) to make a timely decision 

within a short period of time, for example 15 days, constitutes approval of the routine 

maintenance notice. In this context, the commenter would accept proposed 40 CFR 

63.8570(d)(2) as a compliance recordkeeping requirement. An exceedence of the four percent 

annual limitation in proposed 40 CFR 63.8570(d)(2) would still be considered a deviation under 

a revised 40 CFR 63.8620(d). However, there is no basis for the proposed 40 CFR 63.8570(d)(3), 

(4) and (5) in this alternate scenario. The commenter agreed with EPA that the facility would 

continue to operate.

Response 4: The EPA does not agree with the commenter’s request to eliminate the pre-approval 

process for the routine control device maintenance provision in 40 CFR 63.8570(d). Pre-approval 

is essential to ensure that the need and timing for routine control device maintenance are 

justified, describe the maintenance activities and their frequency, explain why the maintenance 

cannot be accomplished during source shutdowns, provide information comparing the emissions 

resulting from shutting down the control device to the emissions resulting from shutting down 

the source entirely, describe how the source plans to comply with applicable requirements while 

the control device is not operating, and provide any other documentation that the Administrator 

needs. EPA notes that its expectation is that this provision will be rarely invoked, because 

sources should normally conduct routine maintenance of the control device when the source is 

not operating.

We also disagree that the provisions in 40 CFR 63.8570(d)(4) and (5) are not needed. We have 

revised paragraph (d)(4) to reference the applicable work practice standard in Table 3 of the rule 

that would ensure continuous compliance, including during periods of control device 

maintenance. 

With respect to the suggestion that the EPA modify the routine maintenance provision to state 

that it will apply if EPA does not act on a source’s request within a set time frame, the EPA 

disagrees that this would be appropriate. As we note above, it is important that the EPA ensure 

that this provision is appropriately applied in each case based on the information provided by the 

source. However, to address the commenter’s underlying concern that EPA might not act within 

sufficient time before the source would want to rely on this provision, EPA is revising the time 

frame for the submission of requests under this provision from 30 days as proposed (see 79 FR 
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75700 (proposed section 63.8630(f)) to 120 days, which provides EPA with additional time to 

review and act on any requests before the source’s compliance date. 

Finally, as a result of its consideration of this provision to address these comments, the EPA has 

made certain other changes to this provision, including (1) calling it an “alternative standard” 

rather than an “exemption” because sources covered by this provision are subject to the 

alternative requirements under this provision and are not exempt from the rule, and (2) stating 

the 120-day submission period in the routine maintenance provision itself rather than only in the 

notification provisions.