[Federal Register Volume 80, Number 145 (Wednesday, July 29, 2015)]
[Rules and Regulations]
[Pages 45279-45338]
[FR Doc No: 2015-16643]

Vol. 80

Wednesday,

No. 145

July 29, 2015

Part II

Environmental Protection Agency

-----------------------------------------------------------------------

40 CFR Part 63

National Emissions Standards for Hazardous Air Pollutants for Mineral
Wool Production and Wool Fiberglass Manufacturing; Final Rule

Federal Register / Vol. 80 , No. 145 / Wednesday, July 29, 2015 /
Rules and Regulations

-----------------------------------------------------------------------

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 63

[EPA-HQ-OAR-2010-1041 and EPA-HQ-OAR-2010-1042; FRL-9928-71-OAR]
RIN 2060-AQ90

National Emissions Standards for Hazardous Air Pollutants for
Mineral Wool Production and Wool Fiberglass Manufacturing

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

-----------------------------------------------------------------------

SUMMARY: This action finalizes the residual risk and technology reviews
(RTR) conducted for the Mineral Wool Production and Wool Fiberglass
Manufacturing source categories regulated under national emission
standards for hazardous air pollutants (NESHAP). Under this action, we
are establishing pollutant-specific emissions limits for hazardous air
pollutants (HAP) that were previously regulated (under a surrogate) and
for HAP that were previously unregulated. This action finalizes first-
time generally available control technologies (GACT) standards for gas-
fired glass-melting furnaces at wool fiberglass manufacturing
facilities that are area sources. We are also amending regulatory
provisions related to emissions during periods of startup, shutdown,
and malfunction (SSM); adding requirements for reporting of performance
testing through the Electronic Reporting Tool (ERT); and making several
minor clarifications and corrections. The revisions in these final
rules increase the level of emissions control and environmental
protection provided by the Mineral Wool Production and Wool Fiberglass
Manufacturing NESHAP.

DATES: This final action is effective on July 29, 2015.

ADDRESSES: The Environmental Protection Agency (EPA) has established
two dockets for this action under Docket ID Nos. EPA-HQ-OAR-2010-1041
(for 40 CFR part 63, subpart DDD) and EPA-HQ-OAR-2010-1042 (for 40 CFR
part 63, subparts NNN and NN). All documents in these dockets are
listed on the www.regulations.gov Web site. Although listed in the
index, some information is not publicly available, e.g., confidential
business information (CBI) or other information whose disclosure is
restricted by statute. Certain other material, such as copyrighted
material, is not placed on the Internet and will be publicly available
only in hard copy form. Publicly available docket materials are
available either electronically through http://www.regulations.gov, or
in hard copy at the EPA Docket Center, EPA WJC West Building, Room
Number 3334, 1301 Constitution Ave. NW., Washington, DC. The Public
Reading Room hours of operation are 8:30 a.m. to 4:30 p.m. Eastern
Time, Monday through Friday. The telephone number for the Public
Reading Room is<PHONE_NUMBER>, and the telephone number for the Air
and Radiation Docket and Information Center is<PHONE_NUMBER>.

FOR FURTHER INFORMATION CONTACT: For questions about this final action,
contact Ms. Susan Fairchild, Sector Policies and Programs Division (D
234-04), Office of Air Quality Planning and Standards, U.S.
Environmental Protection Agency, Research Triangle Park, North
Carolina, 27711; telephone number:<PHONE_NUMBER>; fax number: (919)
541-5600; and email address<EMAIL_ADDRESS>For specific
information regarding the risk modeling methodology, contact Mr. Chris
Sarsony, Health and Environmental Impacts Division (C539-02), Office of
Air Quality Planning and Standards, U.S. Environmental Protection
Agency, Research Triangle Park, North Carolina 27711; telephone number:
(919) 541-4843; fax number:<PHONE_NUMBER>; and email address:
<EMAIL_ADDRESS>For information about the applicability of the
NESHAP to a particular entity, contact Ms. Sara Ayres, Office of
Enforcement and Compliance Assurance, U.S. Environmental Protection
Agency Region 5, 77 West Jackson Boulevard, Mail Code E-19J, Chicago,
IL 60604-3507; telephone number:<PHONE_NUMBER>; and email address:
<EMAIL_ADDRESS>
SUPPLEMENTARY INFORMATION:
    Preamble Acronyms and Abbreviations. We use multiple acronyms and
terms in this preamble. While this list may not be exhaustive, to ease
the reading of this preamble and for reference purposes, the EPA
defines the following terms and acronyms here:

ADAF Age-dependent adjustment factors
AEGL Acute Exposure Guideline Levels
ANSI American National Standards Institute
APA Administrative Procedures Act
BDL Below detection limit
BFS Batch Formulation System
CAA Clean Air Act
CA-REL California reference exposure level
CBI Confidential business information
CDX Central Data Exchange
CEDRI Compliance and Emissions Data Reporting Interface
CEMS Continuous emission monitoring system
CFR Code of Federal Regulations
CO Carbon monoxide
COS Carbonyl sulfide
CPMS Continuous parameter monitoring system
Cr Chromium
CRA Congressional Review Act
CRT Cathode ray tube
DESP Dry electrostatic precipitator
dscm Dry standard cubic meters
EPA Environmental Protection Agency
ERPG Emergency Response Planning Guidelines
ERT Electronic Reporting Tool
ESP Electrostatic precipitator
FA Flame attenuation
FR Federal Register
GACT Generally available control technology
HAP Hazardous air pollutants
HCl Hydrogen chloride
HEPA High efficiency particulate air
HF Hydrogen fluoride
HQ Hazard quotient
ICR Information collection request
IRIS Integrated Risk Information System
Lb/ton Pounds per ton
LOI Loss on ignition
MACT Maximum achievable control technology
MDL Minimum detection limit
MIR Maximum individual risk
NAICS North American Industry Classification System
NAIMA North American Insulation Manufacturers Association
NESHAP National Emission Standards for Hazardous Air Pollutants
NOX Nitrogen oxide
NPV Net present value
NSPS New Source Performance Standards
NSSN National Standards Systems Network
NTTAA National Technology Transfer and Advancement Act
OAQPS Office of Air Quality Planning and Standards
OMB Office of Management and Budget
PB-HAP Persistent and Bioaccumulative-HAP
PM Particulate matter
ppm Parts per million
PRA Paperwork Reduction Act
RACT/BACT/LAER Reasonably Available Control Technology/Best
Available Control Technology/Lowest Achievable Emission Rate
RCRA Resource Conservation and Recovery Act
RDL Representative detection limit
REL Recommended exposure limit
RFA Regulatory Flexibility Act
RIA Regulatory Impact Analysis
RIN Regulatory Information Number
RS Rotary spin
RTR Risk and Technology Review
SAB Science Advisory Board
SBA Small Business Administration
SBAR Small Business Analytical Review
SBREFA Small Business Regulatory Enforcement Flexibility Act
SO2 Sulfur dioxide
SSM Startup, shutdown, malfunction
TOSHI Target organ specific hazard index
TTN Technology Transfer Network
UMRA Unfunded Mandates Reform Act
UPL Upper prediction limit

VCS Voluntary Consensus Standards

    Background Information. On November 25, 2011 (76 FR 72770), the EPA
proposed revisions to the Mineral Wool Production and Wool Fiberglass
Manufacturing NESHAP based on our RTR under Clean Air Act (CAA)
sections 112(f)(2) and (d)(6). We proposed chromium compounds emissions
limits for wool fiberglass furnaces at major sources after finding that
chromium refractories used to construct furnaces degrade with age and
emit continuously-increasing levels of chromium compounds. These
findings were the result of emissions testing conducted on these types
of furnaces indicating significant amounts (550 pounds) of chromium
emissions, 93 percent of which was in the hexavalent (most toxic) form.
The furnaces tested were considered representative of all furnaces at
each facility. In the November 2011 proposal, we also announced that we
had already issued a new information collection request (ICR) to the
wool fiberglass industry to collect data on chromium emissions and
chromium refractory use at all operating wool fiberglass furnaces with
the intent of regulating area sources in a future action.
    In the November 2011 proposal we also proposed to discontinue using
formaldehyde as a surrogate for phenol and methanol in both the Mineral
Wool Production and Wool Fiberglass Manufacturing source categories and
to discontinue using carbon monoxide (CO) as a surrogate for carbonyl
sulfide (COS) in the Mineral Wool Production source category. This
revision was proposed because we found that the surrogate for each
pollutant is not necessarily a reasonable representation of the
pollutant-specific emissions for these source categories (e.g.,
formaldehyde is not invariably present in the binder formulation). We
proposed maximum achievable control technology (MACT) standards under
CAA sections 112(d)(2) and (3) for the HAP phenol and methanol in both
source categories, and COS in the Mineral Wool Production source
category. We also proposed MACT standards for hydrogen fluoride (HF)
and hydrochloric acid (HCl), which are emitted from these source
categories, but were not regulated under the MACT standard.
    On April 15, 2013 (78 FR 22370), the EPA issued a supplemental
proposal that was based on comments to the November 2011 proposal and
new information on processes in both source categories. New emissions
test data for all wool fiberglass furnaces across the industry showed
that the same types of furnaces were in operation at both major and
area sources, but that the emissions profile of electric furnaces
differed from that of gas-fired furnaces (i.e., emissions that could
endanger public health). In that notice, we listed wool fiberglass
manufacturing area sources, and proposed chromium emission limits for
gas-fired wool fiberglass furnaces at area sources, and announced that
the chromium limits at major sources would be specific to gas-fired
furnaces (such as air-gas and oxyfuel furnaces) and not electric
furnaces (such as cold-top and steel shell furnaces).
    On November 13, 2014 (79 FR 68012), the EPA issued a second
supplemental proposal to explain changes to previously proposed
emissions limits for sources in these source categories. We proposed
work practice standards under CAA section 112(h) in lieu of certain
emissions limits, and clarified our use of the upper predictive limit
(UPL) in setting MACT floors. In this action, we are finalizing
decisions and revisions for these rules. We summarize some of the more
significant comments we received regarding the proposed rules and
provide our responses in this preamble. A summary of all other public
comments on the proposal and the EPA's responses to those comments is
available in the memorandum, ``National Emissions Standards for
Hazardous Air Pollutants: Mineral Wool Production and Wool Fiberglass
Manufacturing (Risk and Technology Review)--Summary of Public Comments
and Responses'' (Docket ID Nos. EPA-HQ-OAR-2010-1041 and EPA-HQ-OAR-
2010-1042). ``Track-changes'' versions of the regulatory language that
incorporates the changes in this action are available in the respective
dockets.

Organization of This Document

    The information in this preamble is organized as follows:

I. General Information
    A. Does this action apply to me?
    B. Where can I get a copy of this document and other related
information?
    C. Judicial Review and Administrative Reconsideration
II. Background
    A. What is the statutory authority for this action?
    B. What is the Mineral Wool Production source category and how
does the NESHAP regulate HAP emissions from the source category?
    C. What changes did we propose for the Mineral Wool Production
source category in our November 25, 2011 proposal; April 15, 2013
supplemental proposal; and November 13, 2014 supplemental proposal?
    D. What is the Wool Fiberglass Manufacturing source category and
how does the NESHAP regulate HAP emissions from the source category?
    E. What changes did we propose for major sources in the Wool
Fiberglass Manufacturing source category in our November 25, 2011
proposal; April 15, 2013 supplemental proposal; and November 13,
2014 supplemental proposal?
    F. What did we propose for area sources in the Wool Fiberglass
Manufacturing source category in our November 25, 2011 proposal;
April 15, 2013 supplemental proposal; and November 13, 2014
supplemental proposal?
III. What is Included in the Final Mineral Wool Production Rule?
    A. What are the final rule amendments based on the risk review
for the Mineral Wool Production source category?
    B. What are the final rule amendments based on the technology
review for the Mineral Wool Production source category?
    C. What are the final rule amendments pursuant to CAA sections
112(d)(2) and (3) for the Mineral Wool Production source category?
    D. What are the final rule amendments addressing emissions
during periods of startup and shutdown for the Mineral Wool
Production source category?
    E. What other changes have been made to the Mineral Wool
Production NESHAP?
    F. What are the effective and compliance dates of the new MACT
standards for the Mineral Wool Production source category?
    G. What are the requirements for submission of performance test
data to the EPA?
IV. What is the rationale for our final decisions and amendments for
the Mineral Wool Production source category?
    A. Residual Risk Review for the Mineral Wool Production Source
Category
    B. Technology Review for the Mineral Wool Production Source
Category
    C. MACT Standards for Pollutants Previously Regulated Under a
Surrogate and Previously Unregulated Pollutants
    D. Startup, Shutdown, and Malfunction Provisions for the Mineral
Wool Production Source Category
    E. Other Changes Made to the Mineral Wool Production NESHAP
V. What is Included in the Final Wool Fiberglass Manufacturing Rule
for major sources?
    A. What are the final rule amendments based on the risk review
for the Wool Fiberglass Manufacturing (major sources) source
category?
    B. What are the final rule amendments based on the technology
review for the Wool Fiberglass Manufacturing (major sources) source
category?
    C. What are the final rule amendments pursuant to CAA sections
112(d)(2) and (3) for the Wool Fiberglass Manufacturing (major
sources) source category?
    D. What are the final rule amendments pursuant to CAA section
112(h) for the

Wool Fiberglass Manufacturing (major sources) source category?
    E. What are the final rule amendments for the Wool Fiberglass
Manufacturing (major sources) source category addressing emissions
during periods of startup and shutdown?
    F. What other changes have been made to the Wool Fiberglass
Manufacturing NESHAP (major sources)?
    G. What are the effective and compliance dates of the standards?
    H. What is the status of the Wool Fiberglass Manufacturing MACT
standard amendments under CAA sections 112(d)(2) and (3) for RS
Manufacturing Lines?
    I. What are the requirements for submission of performance test
data to the EPA for the Wool Fiberglass Manufacturing NESHAP?
VI. What is the rationale for our final decisions and amendments for
the Wool Fiberglass Manufacturing source category (major sources)?
    A. Residual Risk Review for the Wool Fiberglass Manufacturing
Source Category (Major Sources)
    B. Technology Review for the Wool Fiberglass Manufacturing
Source Category (Major Sources)
    C. MACT Standards for Pollutants Previously Regulated Under a
Surrogate and Previously Unregulated Pollutants for the Wool
Fiberglass Manufacturing Source Category (Major Sources)
    D. Work Practice Standards for HCl and HF Emissions From
Furnaces in the Wool Fiberglass Manufacturing Source Category (Major
Sources)
    E. Startup, Shutdown, and Malfunction Provisions for the Wool
Fiberglass Manufacturing Source Category (Major and Area Sources)
    F. Other Changes Made to the Wool Fiberglass Manufacturing
NESHAP (Major and Area Sources)
VII. What is included in the Final Wool Fiberglass Manufacturing
Rule for area sources?
    A. Generally Available Control Technology (GACT) Analysis for
Wool Fiberglass Manufacturing Area Sources
    B. What are the final requirements for the Wool Fiberglass
Manufacturing area sources?
    C. What are the effective and compliance dates of the standards
for Wool Fiberglass Manufacturing area sources?
    D. What are the requirements for submission of performance test
data to the EPA for Wool Fiberglass Manufacturing area sources?
VIII. Summary of Cost, Environmental and Economic Impacts and
Additional Analyses Conducted
    A. What are the affected facilities?
    B. What are the air quality impacts?
    C. What are the cost impacts?
    D. What are the economic impacts?
    E. What are the benefits?
    F. What analysis of environmental justice did we conduct?
    G. What analysis of children's environmental health did we
conduct?
IX. Statutory and Executive Order Reviews
    A. Executive Orders 12866: Regulatory Planning and Review and
Executive Order 13563: Improving Regulation and Regulatory Review
    B. Paperwork Reduction Act (PRA)
    C. Regulatory Flexibility Act (RFA)
    D. Unfunded Mandates Reform Act (UMRA)
    E. Executive Order 13132: Federalism
    F. Executive Order 13175: Consultation and Coordination With
Indian Tribal Governments
    G. Executive Order 13045: Protection of Children From
Environmental Health Risks and Safety Risks
    H. Executive Order 13211: Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution or Use
    I. National Technology Transfer and Advancement Act (NTTAA)
    J. Executive Order 12898: Federal Actions To Address
Environmental Justice in Minority Populations and Low-Income
Populations
    K. Congressional Review Act (CRA)

I. General Information

A. Does this action apply to me?

    Regulated Entities. Categories and entities potentially regulated
by this action are shown in Table 1 of this preamble.

 Table 1--NESHAP and Industrial Source Categories Affected by This Final
                                 Action
------------------------------------------------------------------------
               NESHAP and source  category                NAICS \a\ code
------------------------------------------------------------------------
Mineral Wool Production.................................          327993
Wool Fiberglass Manufacturing...........................          327993
------------------------------------------------------------------------
\a\ North American Industry Classification System.

    Table 1 of this preamble is not intended to be exhaustive, but
rather to provide a guide for readers regarding entities likely to be
affected by the final action for the source categories listed. To
determine whether your facility is affected, you should examine the
applicability criteria in the appropriate NESHAP. If you have any
questions regarding the applicability of any aspect of this NESHAP,
please contact the appropriate person listed in the preceding FOR
FURTHER INFORMATION CONTACT section of this preamble.

B. Where can I get a copy of this document and other related
information?

    In addition to being available in the docket, an electronic copy of
this final action will also be available on the Internet through the
Technology Transfer Network (TTN) Web site, a forum for information and
technology exchange in various areas of air pollution control.
Following signature by the EPA Administrator, the EPA will post a copy
of this final action at:  http://www.epa.gov/ttn/atw/woolfib/woolfipg
and at http://www.epa.gov/ttn/atw/minwool/minwopg. Following
publication in the Federal Register, the EPA will post the Federal
Register version and key technical documents at this same Web site.
    Additional information is available on the RTR Web site at http://www.epa.gov/ttn/atw/rrisk/rtrpg.html. This information includes an
overview of the RTR program, links to project Web sites for the RTR
source categories and detailed emissions and other data we used as
inputs to the risk assessments.

C. Judicial Review and Administrative Reconsideration

    Under CAA section 307(b)(1), judicial review of this final action
is available only by filing a petition for review in the United States
Court of Appeals for the District of Columbia Circuit by September 28,
2015. Under CAA section 307(b)(2), the requirements established by this
final rule may not be challenged separately in any civil or criminal
proceedings brought by the EPA to enforce the requirements.
    Section 307(d)(7)(B) of the CAA further provides that ``[o]nly an
objection to a rule or procedure which was raised with reasonable
specificity during the period for public comment (including any public
hearing) may be raised during judicial review.'' This section also
provides a mechanism for the EPA to reconsider the rule ``[i]f the
person raising an objection can demonstrate to the Administrator that
it was impracticable to raise such objection within [the period for
public comment] or if the grounds for such objection arose after the
period for public comment (but within the time specified for judicial
review) and if such objection is of central relevance to the outcome of
the rule.'' Any person seeking to make such a demonstration should
submit a Petition for Reconsideration to the Office of the
Administrator, U.S. EPA, Room 3000, EPA, WJC West Building, 1200
Pennsylvania Ave. NW., Washington, DC 20460, with a copy to both the
person(s) listed in the preceding FOR FURTHER INFORMATION CONTACT
section, and the Associate General Counsel for the Air and Radiation
Law Office, Office of General Counsel (Mail Code 2344A), U.S. EPA, 1200
Pennsylvania Ave. NW., Washington, DC 20460.

II. Background

A. What is the statutory authority for this action?

    Section 112 of the CAA establishes a two-stage regulatory process
to address emissions of HAP from stationary sources. In the first
stage, we must identify categories of sources emitting one or more of
the HAP listed in CAA section 112(b) and then promulgate technology-
based NESHAP for those sources. ``Major sources'' are those that emit,
or have the potential to emit, any single HAP at a rate of 10 tons per
year or more, or 25 tons per year or more of any combination of HAP.
For major sources, these standards are commonly referred to as maximum
achievable control technology or MACT standards and must reflect the
maximum degree of emission reductions of HAP achievable (after
considering cost, energy requirements, and non-air quality health and
environmental impacts). In developing MACT standards, CAA section
112(d)(2) directs the EPA to consider the application of measures,
processes, methods, systems or techniques, including but not limited to
those that reduce the volume of or eliminate HAP emissions through
process changes, substitution of materials, or other modifications;
enclose systems or processes to eliminate emissions; collect, capture,
or treat HAP when released from a process, stack, storage, or fugitive
emissions point; are design, equipment, work practice, or operational
standards; or any combination of the above.
    For these MACT standards, the statute specifies certain minimum
stringency requirements, which are referred to as MACT floor
requirements, and which may not be based on cost considerations. See
CAA section 112(d)(3). For new sources, the MACT floor cannot be less
stringent than the emission control achieved in practice by the best-
controlled similar source. The MACT standards for existing sources can
be less stringent than floors for new sources, but they cannot be less
stringent than the average emission limitation achieved by the best-
performing 12 percent of existing sources in the category or
subcategory (or the best-performing five sources for categories or
subcategories with fewer than 30 sources). In developing MACT
standards, we must also consider control options that are more
stringent than the floor, under CAA section 112(d)(2). We may establish
standards more stringent than the floor, based on the consideration of
the cost of achieving the emissions reductions, any non-air quality
health and environmental impacts, and energy requirements.
    In the second stage of the regulatory process, the CAA requires the
EPA to undertake two different analyses, which we refer to as the
technology review and the residual risk review. Under the technology
review, we must review the technology-based standards and revise them
``as necessary (taking into account developments in practices,
processes, and control technologies)'' no less frequently than every 8
years, pursuant to CAA section 112(d)(6). Under the residual risk
review, we must evaluate the risk to public health remaining after
application of the technology-based standards and revise the standards,
if necessary, to provide an ample margin of safety to protect public
health or to prevent, taking into consideration costs, energy, safety,
and other relevant factors, an adverse environmental effect. The
residual risk review is required within 8 years after promulgation of
the technology-based standards, pursuant to CAA section 112(f). In
conducting the residual risk review, if the EPA determines that the
current standards provide an ample margin of safety to protect public
health, it is not necessary to revise the MACT standards pursuant to
CAA section 112(f).\1\ For more information on the statutory authority
for this rule, see the November 25, 2011, proposal (76 FR 72773).
---------------------------------------------------------------------------

    \1\ The U.S. Court of Appeals has affirmed this approach of
implementing CAA section 112(f)(2)(A): NRDC v. EPA, 529 F.3d 1077,
1083 (D.C. Cir. 2008) (``If EPA determines that the existing
technology-based standards provide an 'ample margin of safety,' then
the Agency is free to readopt those standards during the residual
risk rulemaking.'').
---------------------------------------------------------------------------

    CAA sections 112(c)(3), (d)(5), and (k)(3) address regulation of
area sources. Collectively, these sections are the basis of the Area
Source Program under the Urban Air Toxics Strategy (Strategy).\2\ Area
sources are those that emit less than the major source threshold of HAP
(i.e., less than 10 tons per year of a single pollutant or 25 tons per
year of a combination of HAP. Under the Strategy, we must regulate
emissions of the 30 most toxic HAP emitted by area sources, based on
generally available control technology (GACT), at a minimum. These
provisions do not require the EPA to regulate all HAP from all HAP-
emitting processes as we must do when setting MACT standards. On April
15, 2013, consistent with the Strategy, the agency added gas-fired
glass-melting furnaces located at area sources to the source category
list \3\ \4\ and proposed emissions standards for particulate matter
(PM) and chromium compounds from these sources at wool fiberglass
manufacturing facilities (78 FR 22370). On November 13, 2014, we
withdrew our previously proposed GACT limits for PM and proposed to
only require total chromium compounds emissions limits for these
sources. Reduction of PM is accomplished through chromium reductions
because chromium is the toxic pollutant entrained within PM that is
emitted by these sources. We are finalizing GACT limits for chromium
compound emissions for gas-fired glass-melting furnaces in the Wool
Fiberglass Manufacturing area source category.
---------------------------------------------------------------------------

    \2\ For EPA's document on the Urban Air Toxics Strategy, see 64
FR 38706-38715-716 (July 19, 1999).
    \3\ For the listing documents of the Strategy, see 64 FR 38075,
July 19, 1999; 67 FR 43112, June 26, 2002; 67 FR 70427, November 22,
2002; 73 FR 78637, December 23, 2008; and 74 FR 30366, June 25,
2009.
    \4\ We have made several revisions to the CAA section 112(c)(3)
list since its issuance: 67 FR 43112, June 26, 2002; 67 FR 70427,
November 22, 2002; 73 FR 78637, December 23, 2008; 74 FR 30366, June
25, 2009.
---------------------------------------------------------------------------

    With this regulation, pursuant to CAA sections 112(c)(3) and
(k)(3)(B), the agency will have subjected additional sources to
regulation for the urban metal HAP chromium compounds, which is wholly
consistent with the goals of the Strategy. For more information on the
statutory authority for this rule, see the November 25, 2011,
supplemental proposal (76 FR 72770), the April 15, 2013, supplemental
proposal (78 FR 22375-22376), and the November 13, 2014, supplemental
proposal (79 FR 68012).

B. What is the Mineral Wool Production source category and how does the
NESHAP regulate HAP emissions from the source category?

    The EPA promulgated the Mineral Wool Production NESHAP on June 1,
1999 (64 FR 29490). The standards are codified at 40 CFR part 63,
subpart DDD. The Mineral Wool Production industry consists of
facilities that produce mineral wool fiber from slag, rock, or other
materials, excluding sand or glass. The source category covered by this
MACT standard currently consists of eight facilities.
    Mineral wool is a material used mainly for thermal and acoustical
insulation. This category includes, but is not limited to, the
following process units: A cupola furnace for melting the mineral
charge; a blow chamber in which air and, in some cases, a binder are
drawn over the fibers, forming them to a screen; a curing oven to bond
the fibers; and a cooling compartment. The 1999 NESHAP rule set
emissions limits

for PM from new and existing cupolas, CO from new cupolas, and
formaldehyde from new and existing curing ovens.

C. What changes did we propose for the Mineral Wool Production source
category in our November 25, 2011 proposal; April 15, 2013 supplemental
proposal; and November 13, 2014 supplemental proposal?

    On November 25, 2011, the EPA published a proposed rule for the
Mineral Wool Production NESHAP, 40 CFR part 63, subpart DDD, that
proposed RTR amendments to this standard under CAA sections 112(d)(6)
and (f)(2). In that proposal, we stated that maximum individual risk
(MIR) for cancer was 4-in-1 million based on available test data for
actual emissions and 10-in-1 million based on the MACT-allowable
emission limits of the rule. We proposed, considering all available
information, that risks were acceptable.
    For PM, we reviewed the control technologies in use by the industry
and did not find any improvements or developments in practices,
processes, and control technologies since the 1999 MACT standard was
promulgated. Therefore, we did not propose amendments to the PM
standards under either CAA sections 112(f)(2) or (d)(6).
    We also proposed to discontinue use of surrogates where we
determined that the surrogacy was not reasonable. We proposed to
discontinue using CO as a surrogate for COS, and to discontinue use of
formaldehyde as a surrogate for phenol and methanol. Based on new
source test data and CAA sections 112(d)(2) and (3), we proposed MACT
floor emission limits for existing and new sources of COS, phenol, and
methanol, pollutants that were previously regulated under a surrogate;
and MACT floor emission limits for formaldehyde, the former surrogate.
We retained PM as a surrogate for non-mercury HAP metals because there
is a reasonable surrogate relationship. We also proposed emissions
limits for HF and HCl, two pollutants that were previously unregulated,
and proposed alternative emission limits for periods of startup and
shutdown.
    On April 15, 2013, we published a supplemental proposal for the
Mineral Wool Production NESHAP that took into consideration the
comments received on the November 2011 proposal, new emissions testing
for horizontal lines, and subcategorization of cupolas based on design
and raw material use. We withdrew our previously-proposed alternative
emission limits for startup and shutdown, and instead proposed that
sources may demonstrate compliance with the MACT floor emission limits
during periods of startup and shutdown by keeping records showing that
the emissions from cupolas were routed to air pollution control devices
operated at the parameters established by the most recent performance
test that showed compliance with the standard.
    On November 13, 2014, the EPA published a second supplemental
proposal for the Mineral Wool Production NESHAP that took into
consideration comments received on the 2013 supplemental proposal,
explained changes to previously proposed MACT limits for sources in
this source category and clarified our use of the UPL in setting the
MACT floors. In that proposal, we also proposed work practice standards
under CAA section 112(h) for periods of startup and shutdown based on
the practices used by the best performers among mineral wool producers
to minimize emissions during these activities.

D. What is the Wool Fiberglass Manufacturing source category and how
does the NESHAP regulate HAP emissions from the source category?

    The EPA promulgated the Wool Fiberglass Manufacturing NESHAP on
June 14, 1999 (62 FR 31695). The standards are codified at 40 CFR part
63, subpart NNN. The Wool Fiberglass Manufacturing source category is
defined as any facility engaged in producing wool fiberglass from sand,
feldspar, sodium sulfate, anhydrous borax, boric acid or any other
materials. The Wool Fiberglass Manufacturing industry consists of
facilities that produce bonded building insulation using a rotary spin
(RS) manufacturing line, and facilities that produce bonded pipe
insulation and bonded heavy-density products using a flame attenuation
(FA) manufacturing line. The 1999 MACT standards currently apply to 10
major sources in the wool fiberglass industry. Another 20 facilities
are area sources.
    Wool fiberglass is used primarily as a thermal and acoustical
insulation for buildings, automobiles, aircraft, appliances, ductwork
and pipes. This category includes, but is not limited to, the following
process units: A furnace for melting the mineral charge; a bonded line
operation in which air and a binder are drawn over the fibers and cured
in an oven to bond the fibers; and a cooling compartment. The 1999
NESHAP rule set emissions limits for PM from new and existing glass-
melting furnaces and formaldehyde emissions from new FA and new and
existing RS bonded lines.

E. What changes did we propose for major sources in the Wool Fiberglass
Manufacturing source category in our November 25, 2011 proposal; April
15, 2013 supplemental proposal; and November 13, 2014 supplemental
proposal?

    On November 25, 2011, the EPA published a proposed rule for the
Wool Fiberglass Manufacturing NESHAP to amend the standard based on our
RTR analyses. In that proposal, we found under CAA section 112(f)(2)
that the MIR for cancer, primarily due to emissions of hexavalent
chromium and formaldehyde, was 40-in-1 million based on actual
emissions and 60-in-1 million based on MACT-allowable emissions. The
maximum chronic non-cancer target organ specific hazard index (TOSHI)
value based on actual emissions was 0.2 with emissions of formaldehyde
dominating those impacts. The acute noncancer hazard quotient (HQ),
based on the recommended exposure limit (REL) for formaldehyde, was 30.
The acute noncancer HQ, based on the Acute Exposure Guideline Levels
(AEGL-1) for formaldehyde, was 2. We determined that nothing prevents
construction of a high chromium emitting furnace at any wool fiberglass
facility. Therefore, we evaluated risk under an auxiliary risk
assessment which asked, ``if all wool fiberglass facilities emitted
hexavalent chromium at the level of the highest emitter (that is, 450
pounds of hexavalent chromium annually), what would be the risk to
human health?'' The MIR under the auxiliary risk analysis exceeded 100-
in-one million at four facilities, a level we consider unacceptable.
    Although the risk from actual emissions were considered to be well
within a level we consider acceptable, we proposed that risk due to
hexavalent chromium could be further reduced to achieve an ample margin
of safety. The chromium compounds limit would also prevent operation of
another high-chromium emitting furnace in this source category. We
therefore proposed chromium compounds emission limits of 0.00006 pounds
of chromium compounds per ton of glass pulled, under CAA section
112(f)(2).
    We proposed under CAA section 112(d)(6) that the control
technologies in place on wool fiberglass manufacturing furnaces were
essentially the same as existed at the time the MACT standards were
promulgated, but that there have been improvements in both the
operation and the design of furnaces and their control technologies
since that time. As a result, we proposed

emissions limits for both PM and total chromium compounds for gas-fired
glass-melting furnaces at major sources, under CAA section 112(d)(6),
and indicated our intent to list and regulate chromium compounds at
area sources in a future action.
    In the November 2011 proposal, similar to how we addressed the
mineral wool source category, we also proposed in wool fiberglass to
discontinue use of formaldehyde as a surrogate for phenol and methanol
because the surrogacy was not reasonable. We proposed phenol,
formaldehyde, and methanol MACT floor emission limits based on
information collected in 2010 for two subcategories of bonded lines
under CAA sections 112(d)(2) and (3). We proposed limits for FA lines
that apply to all lines without further subcategorization, and proposed
alternative emission limits for periods of startup and shutdown. In
that notice, we also announced that we had issued an ICR under our
section 114 authority to gather additional emission information on
furnace chromium emissions.
    In our April 2013 supplemental proposal, we took into consideration
comments received on the November 2011 proposal, new process and
chromium emissions test data, and related furnace data collected under
a CAA section 114 ICR.
    We further proposed revised PM emission limits for glass-melting
furnaces at wool fiberglass manufacturing facilities that are major
sources under CAA section 112(d)(6), presented the results of the new
chromium emission testing collected from glass-melting furnaces, and
required that the chromium emission limits proposed under CAA sections
112(d)(6) and (f)(2) would apply only to gas-fired glass-melting
furnaces at major sources. We proposed an alternative compliance
provision for startup and shutdown that would require sources to keep
records showing that emissions were routed to the air pollution control
devices and that these control devices were operated at the parameters
established during the most recent performance test that showed
compliance with the applicable emission limits. For electric cold-top
furnaces, we proposed limiting raw material content to only cullet
during startup and shutdown in recognition of the fact that these
furnaces do not allow control devices to be operated during startup.
For all other glass-melting furnaces, we also required preheating the
empty furnace using only natural gas.
    On November 13, 2014, the EPA published a second supplemental
proposal. For major sources, the 2014 supplemental proposal took into
consideration comments received on the 2013 supplemental proposal,
withdrew the previously proposed amendments for affirmative defense,
explained changes to previously proposed limits for major sources in
this source category, proposed work practice standards under CAA
section 112(h) for periods of startup and shutdown, and clarified our
use of the UPL in setting MACT floors.

F. What did we propose for area sources in the Wool Fiberglass
Manufacturing source category in our November 25, 2011 proposal; April
15, 2013 supplemental proposal; and November 13, 2014 supplemental
proposal?

    In the November 2011 proposal, we noted our intent to potentially
list wool fiberglass manufacturing area sources and to use data from
the CAA section 114 letter noted above to regulate wool fiberglass area
sources in a future action.
    On April 15, 2013, the EPA published a supplemental proposal that
listed gas-fired glass-melting furnaces at wool fiberglass
manufacturing facilities that are area sources as a source category
under CAA sections 112(c)(3)and (k)(3). We also proposed first-time PM
and total chromium compounds standards for gas-fired glass-melting
furnaces at wool fiberglass manufacturing facilities that are area
sources under CAA section 112(d)(5).
    We proposed GACT standards of 0.00006 pounds of chromium compounds
per ton of glass pulled and 0.33 pounds of PM per ton of glass pulled.
These were the same limits that we proposed for gas-fired glass-melting
furnaces located at major sources in the Wool Fiberglass Manufacturing
source category. To maintain consistency with the major source rule, we
proposed the same provisions for startup, shutdown, malfunction,
testing, monitoring, and recordkeeping that we proposed for major
sources.
    On November 13, 2014, the EPA published a second supplemental
proposal. For area sources, the 2014 supplemental proposal took into
consideration comments received on the 2013 supplemental proposal,
withdrew the previously proposed provisions for affirmative defense,
explained changes to previously proposed limits for sources in this
source category, and proposed work practice standards under CAA section
112(h) for periods of startup and shutdown.

III. What is included in the final Mineral Wool Production rule?

    This action finalizes the EPA's determinations pursuant to the RTR
provisions of CAA section 112 for the Mineral Wool Production source
category and amends the Mineral Wool Production NESHAP based on those
determinations. This action also finalizes MACT emission limits under
CAA sections 112(d)(2) and (3), work practice standards for periods of
startup and shutdown under CAA section 112(h), and other changes to the
NESHAP discussed in section III.E of this preamble.
    In this action, we are finalizing, as previously proposed, the
emission limits for HAP-emitting processes in the Mineral Wool
Production source category, as shown in Table 2 of this preamble.

                                        Table 2--Emission Limits for the Mineral Wool Production Source Category
--------------------------------------------------------------------------------------------------------------------------------------------------------
           Process                  Subcategory              HAP           2011 Proposal        2013 Proposal        2014 Proposal         Final rule
--------------------------------------------------------------------------------------------------------------------------------------------------------
Cupolas......................  Existing Open-top....  COS.............  3.3................  6.8................  No change..........  6.8
                               New Open-top.........  COS.............  0.017..............  4.3................  3.2................  3.2
                               Existing Closed-top..  COS.............  3.3................  3.4................  No change..........  3.4
                               New Closed-top.......  COS.............  0.017..............  0.025..............  0.062..............  0.062
                               Existing Processing    HF..............  0.014..............  0.16...............  No change..........  0.16
                                Slag.
                                                      HCl.............  0.0096.............  0.21...............  0.44...............  0.44
                               New Processing Slag..  HF..............  0.014..............  0.16...............  0.015..............  0.015
                                                      HCl.............  0.0096.............  0.21...............  0.012..............  0.012
                               Existing Not           HF..............  0.014..............  0.13...............  No change..........  0.13
                                Processing Slag.
                                                      HCl.............  0.0096.............  0.43...............  No change..........  0.43
                               New Not Processing     HF..............  0.014..............  0.13...............  0.018..............  0.018
                                Slag.
                                                      HCl.............  0.0096.............  0.43...............  0.015..............  0.015

Bonded Lines.................  Vertical (Existing     Formaldehyde....  0.46...............  2.7................  2.4................  2.4
                                and New) Combined     Phenol..........  0.52...............  0.74...............  0.71...............  0.71
                                Collection and        Methanol........  0.63...............  1.0................  0.92...............  0.92
                                Curing Operations.
                               Horizontal (Existing   Formaldehyde....  0.054..............  No change..........  0.63...............  0.63
                                and New) Combined     Phenol..........  0.15...............  No change..........  0.12...............  0.12
                                Collection and        Methanol........  0.022..............  No change..........  0.49...............  0.49
                                Curing Operations.
                               Drum (Existing and     Formaldehyde....  0.067..............  0.18...............  0.17...............  0.17
                                New) Combined         Phenol..........  0.0023.............  1.3................  0.85...............  0.85
                                Collection and        Methanol........  0.00077............  0.48...............  0.28...............  0.28
                                Curing Operations.
--------------------------------------------------------------------------------------------------------------------------------------------------------

A. What are the final rule amendments based on the risk review for the
Mineral Wool Production source category?

    As presented in the November 2014 supplemental proposal, we are
finalizing our determination that risks from the Mineral Wool
Production source category are acceptable, the current standards
provide an ample margin of safety to protect public health and prevent
an adverse environmental effect. We are, therefore, not requiring
additional controls and are thus readopting the existing standards
under section 112(f)(2).

B. What are the final rule amendments based on the technology review
for the Mineral Wool Production source category?

    As discussed in the November 2011 proposal (76 FR 72786-72787,
72798), we identified and evaluated the developments in practices,
processes, and control technologies that have occurred since the 1999
MACT rules were promulgated. In cases where we identified such
developments, we analyzed the technical feasibility and the estimated
impacts (e.g., costs, emissions reductions, risk reductions) of
applying these developments. We then decided, based on impacts and
feasibility, whether it was necessary to propose amendments to the
regulation to require any of the identified developments.
    Based on our analyses of the data, information collected under the
voluntary ICR, our general understanding of both of the industries and
other available information on potential controls for these industries,
we identified potential developments \5\ in practices, processes, and
control technologies.
---------------------------------------------------------------------------

    \5\ For the purpose of this exercise, we considered developments
not identified or considered during development of the 1999 MACT
rules, including any add-on control technology or equipment; any
improvements in technology or equipment that could result in
significant additional emissions reduction; any work practice or
operational procedure; any process change or pollution prevention
alternative that could be broadly applied to the industry; and any
development in equipment or technology that could result in
decreased HAP emissions.
---------------------------------------------------------------------------

    In addition to reviewing the practices, processes, and technologies
that were not considered at the time we developed the 1999 MACT rules,
we reviewed a variety of data sources for the mineral wool industry.
This review included the NESHAP for various industries promulgated
after the 1999 MACT rules, regulatory requirements and technical
analyses associated with these regulatory actions to identify any
practices, processes, and control technologies considered in these
efforts that could possibly be applied to emissions sources in the
Mineral Wool Production source category, as well as the costs, non-air
impacts, and energy implications associated with the use of these
technologies.
    We additionally consulted the EPA's Reasonably Available Control
Technology/Best Available Control Technology/Lowest Achievable Emission
Rate (RACT/BACT/LAER) Clearinghouse to identify potential technology
advances, and searched this database to determine whether it contained
any practices, processes, or control technologies for the types of
processes covered by the mineral wool production rule.
    We also requested information from facilities regarding
developments in practices, processes or control technologies and we
reviewed other information sources, such as state and local permitting
agency databases and industry-supported databases. For more
information, see the ``Technology Review for the Mineral Wool
Production Source Category Memorandum'' in the docket to this rule.
    As a result of our technology review under CAA section 112(d)(6)
for the Mineral Wool Production source category, we determined that
there are no developments in practices, processes, and control
technologies that warrant revisions to this MACT standard. We are
therefore not amending the standards under CAA section 112(d)(6).

C. What are the final rule amendments pursuant to CAA sections
112(d)(2) and (3) for the Mineral Wool Production source category?

    This action finalizes the removal of formaldehyde as a surrogate
for phenol and methanol, and the removal of CO as a surrogate for COS,
as earlier explained in this preamble and as proposed on November 25,
2011 (76 FR 72770). We also are finalizing the proposed COS, HCl, and
HF emission limits for cupolas and the proposed emission limits for
formaldehyde, methanol, and phenol for bonded lines developed as a
result of new representative detection limit (RDL) values, new source
test data and our approach for calculating MACT floors based on limited
data sets, as discussed in section III.B of the November 2014
supplemental proposal preamble. These final rule requirements for the
Mineral Wool Production NESHAP are consistent with the provisions
discussed in our various proposals.

D. What are the final rule amendments addressing emissions during
periods of startup and shutdown for the Mineral Wool Production source
category?

    We are finalizing, as proposed, amendments to the Mineral Wool
Production NESHAP to eliminate the SSM exemption. Consistent with
Sierra Club v. EPA, 551 F. 3d 1019 (D.C. Cir. 2008), the EPA has
established work practice standards for periods of startup and shutdown
under CAA section 112(h) because measurement of the emissions is not
practicable due to technological and economic limitations. Emissions
are not at steady state during startup and shutdown (a necessary factor
for accurate emissions testing), and the varying stack conditions, gas
compositions and low emission rates make accurate emission measurements
impracticable. In addition, the startup period for mineral wool cupolas
is usually 2 hours, which is too short a

time in which to conduct source testing. We are finalizing under CAA
section 112(h), as previously proposed in the November 2014
supplemental proposal, standards requiring affected sources to comply
with work practices that are used by the best performers during periods
of startup and shutdown. The best performers in the mineral wool
industry use one of two possible work practices: either they route any
cupola emissions that occur during startup and shutdown to an operating
baghouse, or, alternatively, operate the cupola during startup and
shutdown with three percent excess oxygen. Regarding the first
alternative, baghouses achieve the same outlet concentrations
regardless of pollutant loading in the emission stream, and
fluctuations in pollutants or exhaust flow rate do not affect the
overall level of emissions at the outlet of this control device.
Regarding the second alternative, operating the cupola with excess
oxygen prevents the formation of pollutants that would otherwise be
routed to existing controls.
    In the final rule, we are specifying work practice standards that
require items of equipment that are required or utilized for compliance
with subpart DDD to be operating during startup and shutdown,
designating when startups and shutdowns begin, and specifying
recordkeeping requirements for startup and shutdown periods. We are
also revising Table 1 to subpart DDD of part 63 (General Provisions
applicability table) to change several references related to
requirements that apply during periods of SSM. We are eliminating or
revising certain recordkeeping and reporting requirements related to
the eliminated SSM exemption.

E. What other changes have been made to the Mineral Wool Production
NESHAP?

    We are finalizing, as proposed, addition of EPA Methods 26A and 320
in appendix A part 63 for measuring the concentrations of HCl and HF.
We are finalizing, as proposed, the requirement for existing sources to
conduct performance tests to demonstrate compliance with the emission
limits for cupolas and combined collection/curing operations no later
than July 30, 2018 and every 5 years thereafter. We are finalizing, as
proposed, the requirement for new sources to comply with the emission
limits of the final rule on July 29, 2015, or upon the first cupola
campaign, whichever is later, and to conduct performance tests to
demonstrate compliance with the emission limits for cupolas and
combined collection/curing operations within 180 days of the applicable
compliance date.
    We are also adding an alternative operating limit for cupolas that
provides owners or operators the option of maintaining the percent
excess oxygen in the cupola at or above the level established during
the performance test. In addition, we are finalizing editorial changes
to the performance testing and compliance procedures to specify
formaldehyde, methanol, phenol, and COS rather than only the surrogates
formaldehyde and CO. In this action, we are finalizing, as proposed,
definitions for ``closed-top cupola,'' ``open-top cupola,'' ``combined
collection/curing operations'' and ``incinerator.'' We are also adding
a definition for ``slag.'' The 2013 supplemental proposal indicated
that we would add such a definition (78 FR 22386). Slag is the primary
contributing factor to the formation of HF and HCl in the cupola
emissions, and is, for some mineral wool formulas, a necessary
ingredient for the production of mineral wool. We subcategorized
cupolas according to their use of slag as a raw material in the cupola,
and are in this final rule defining slag in 40 CFR 63.1196 to mean the
by-product materials separated from metals during smelting and refining
of raw ore.
    We are also making minor corrections to the citations in Table 1
(part 63 General Provision applicability table) to reflect both the
final amendments in this action, and the revisions that have been made
to the General Provisions since 1999.

F. What are the effective and compliance dates of the new MACT
standards for the Mineral Wool Production source category?

    The new MACT standards for the Mineral Wool Production source
category being promulgated in this action are effective on July 29,
2015. The compliance date for existing cupolas and combined collection/
curing operations is July 30, 2018. New sources must comply with the
all of the standards immediately upon the effective date of the
standard, July 29, 2015, or upon initial startup, whichever is later.
    Mineral wool producers are predominantly small businesses. Prior to
the November 25, 2011, proposal, we found there was potentially a
significant impact to a substantial number of small entities (SISNOSE),
and convened a small business advocacy review (SBAR) panel. In that
process, the EPA conducted meetings with mineral wool companies and the
Small Business Office of Advocacy in order to determine ways in which
the impact and burden to small entities could be reduced while
continuing to meet the requirements of the CAA. Stakeholders requested
up to 3 years to comply with the standards once they were promulgated,
in order to be able to install controls, find sources of low-sulfur
coke and low-chloride slag, and to conduct performance testing. In
subsequent proposals, we subcategorized cupolas according to design and
according to raw material use, and can certify that the final rule will
not have a SISNOSE. However, we believe that it is still appropriate to
retain the proposed compliance date of 3 years after promulgation
because the added compliance emissions testing and any process changes
sources needed to comply could become significant if the compliance
time were shortened to less than the 3 years allowed for standards
developed under CAA sections 112(d)(2) and (3).

G. What are the requirements for submission of performance test data to
the EPA?

    As stated in the proposed preamble to the November 2011 proposal,
the EPA is taking a step to increase the ease and efficiency of data
submittal and data accessibility. Specifically, the EPA is requiring
owners and operators of affected facilities to submit electronic copies
of certain required performance test reports.
    As mentioned in the preamble of the November 2011 proposal, data
will be collected by direct computer-to-computer electronic transfer
using EPA-provided software. As discussed in the November 2011
proposal, the EPA-provided software is an electronic performance test
report tool called the ERT. The ERT will generate an electronic report
package which will be submitted to the Compliance and Emissions Data
Reporting Interface (CEDRI) and then archived to the EPA's Central Data
Exchange (CDX). A description and instructions for use of the ERT can
be found at http://www.epa.gov/ttn/chief/ert/index.html, and CEDRI can
be accessed through the CDX Web site at http://www.epa.gov/cdx.
    The requirement to submit performance test data electronically to
the EPA does not create any additional performance testing and will
apply only to those performance tests conducted using test methods that
are supported by the ERT. A listing of the pollutants and test methods
supported by the ERT is available at the ERT Web site. The EPA
believes, through this approach, industry will save time in the

performance test submittal process. Additionally, this rulemaking
benefits industry by cutting back on recordkeeping costs as the
performance test reports that are submitted to the EPA using CEDRI are
no longer required to be kept in hard copy.
    As mentioned in the preamble of the November 2011 proposal, state,
local, and tribal agencies will benefit from more streamlined and
accurate review of performance test data that will be available on the
EPA WebFIRE database. The public will also benefit. Having these data
publicly available enhances transparency and accountability. For a more
thorough discussion of electronic reporting of performance tests using
direct computer-to-computer electronic transfer and using EPA-provided
software, see the discussion in the preamble of the November 2011
proposal.
    In summary, in addition to supporting regulation development,
control strategy development, and other air pollution control
activities, having an electronic database populated with performance
test data will save industry; state, local, and tribal agencies; and
the EPA significant time, money, and effort, while improving the
quality of emission inventories, air quality regulations and enhancing
the public's access to this important information.

IV. What is the rationale for our final decisions and amendments for
the Mineral Wool Production source category?

    For each topic, this section provides a description of what we
proposed and what we are finalizing for the subject, the EPA's
rationale for the final decisions and amendments and a summary of key
comments and responses. For all comments not discussed in this
preamble, comment summaries and the EPA's responses can be found in the
comment summary and response document available in the dockets for each
source category.

A. Residual Risk Review for the Mineral Wool Production Source Category

1. What did we propose pursuant to CAA section 112(f) for the Mineral
Wool Production source category?
    Pursuant to CAA section 112(f), we conducted a residual risk
assessment on the Mineral Wool Production source category and presented
the results of this assessment, along with our proposed decisions
regarding risk acceptability and ample margin of safety, in the
November 2011 proposed rule (76 FR 72798). Based on the inhalation risk
assessment, we estimated that the MIR could be up to 4-in-1 million due
to actual emissions and up to 10-in-1 million due to MACT-allowable
emissions, mainly due to formaldehyde stack emissions. We estimated
that the incidence of cancer based on actual emissions is 0.0004 excess
cancer cases per year or one case every 2,500 years, and that about
1,700 people face a cancer risk greater than 1-in-1 million due to HAP
emissions from the mineral wool production source category.
    That risk assessment indicated that the maximum modeled chronic
non-cancer TOSHI value for the Mineral Wool Production source category
could be up to 0.04 with emissions of formaldehyde dominating those
impacts, indicating no significant potential for chronic non-cancer
impacts.
    Our screening analysis for worst-case acute impacts indicated the
potential for only one pollutant, formaldehyde, to exceed an HQ value
of 1 at only one facility in the Mineral Wool Production source
category, with a potential maximum HQ up to 8. A refined emissions
multiplier of 3 was used to estimate the peak hourly emission rates
from the average rates.
    Consequently, in November 2011 we proposed that risks from this
source category were acceptable. In addition, we did not identify cost-
effective options that would further reduce risk under our ample margin
of safety analysis. Therefore, we proposed that the current standards
for the Mineral Wool Production source category provide an ample margin
of safety to protect public health. We also determined that HAP
emissions from this source category were not expected to result in
adverse environmental effects.
    In the April 2013 supplemental proposal, we revised the risk
assessment to reflect new emissions data submitted by the industry
following the 2011 proposal, the development of subcategories for HCl
and HF emissions from slag- and nonslag-processing cupolas, and
subcategories for COS emissions from closed- and open-top cupolas. As
noted in the 2013 supplemental proposal, the risks estimated in our
revised assessment under CAA section 112(f)(2) from actual emissions
increased slightly (based on the new data) compared to the risk
assessment conducted for the 2011 proposal. The actual MIR for cancer
increased from 4-in-1 million to 10-in-1 million. The maximum chronic
non-cancer TOSHI value for the source category increased from 0.04 to
0.12 with emissions of formaldehyde dominating those impacts,
indicating no significant potential for chronic noncancer impacts. The
acute noncancer HQ, based on the REL for formaldehyde, increased from 8
to 20. The acute noncancer HQ, based on the AEGL-1 for formaldehyde,
increased from 0.4 to 1.1. While the risk increased slightly based on
the new source test data, we noted that that our findings regarding
risk acceptability and ample margin of safety remained unchanged.
    In our November 2014 supplemental proposal, we also revised the
draft risk assessment under CAA section 112(f)(2) based on new
emissions data collected by the industry and updates to the model and
model libraries. The new test data that were received did not change
our estimate of risk from actual emissions when compared to the risk
assessment conducted for the 2013 supplemental proposal. The risk from
mineral wool production continued to be driven by formaldehyde and to
be well within a level we consider to be acceptable. The MIR for cancer
for actual baseline emissions remained 10-in-1 million, with the acute
noncancer HQ remaining at 20 for the REL and at 1 for the AEGL-1. The
maximum chronic non-cancer TOSHI value based on actual emissions
remained at 0.1 with emissions of formaldehyde dominating those
impacts, indicating no significant potential for chronic noncancer
impacts.
    The MIR for cancer from mineral wool production due to allowable
emissions (under the original MACT standard) was estimated to be 30-in-
1 million (formaldehyde). Facilities actually emit formaldehyde at
levels lower than allowed under the 1999 MACT standard, and the limits
in the final rule codify formaldehyde (and the other HAP) limits at the
actual emissions levels. As a result, the potential MIR for cancer due
to allowable emissions after implementation of the standard is
estimated to be 10-in-1 million. Therefore, the MIR based on emissions
at the level of this standard (i.e., what sources are permitted to
emit) decreased by a factor of 3 from MACT-allowable levels. Additional
information on the risk assessment can be found in the document titled,
``Residual Risk Assessment for the Mineral Wool Production and Wool
Fiberglass Manufacturing in Support of the June 2015 Final Rule''
available in the docket for this action (EPA-HQ-OAR-2010-1041).

2. How did the risk review change for the Mineral Wool Production
source category?
    We have not changed any aspect of the risk assessment since the
November 2014 supplemental proposal.
3. What key comments did we receive on the risk review for the Mineral
Wool Production source category, and what are our responses?
    The comments received on the proposed risk review were generally
supportive of our determination of risk acceptability and ample margin
of safety analysis and requirement for additional control. A summary of
the comments received regarding the risk acceptability and ample margin
of safety analysis and our responses can be found in the comment
summary and response document available in the docket for this action
(EPA-HQ-OAR-2010-1041). None of the public comments resulted in changes
to the conclusions of our risk analysis.
4. What is the rationale for our final approach and final decisions for
the risk review for the Mineral Wool Production source category?
    As explained in the various proposals and in section IV.A.1 of this
preamble, our assessment of residual risk from the Mineral Wool
Production source category shows that risks from the source category
are acceptable, the current standards provide an ample margin of safety
to protect public health, and prevent an adverse environmental effect.
We are, therefore, not requiring additional controls and are thus
readopting the existing standards under section 112(f)(2).

B. Technology Review for the Mineral Wool Production Source Category

1. What did we propose pursuant to CAA section 112(d)(6) for the
Mineral Wool Production source category?
    Pursuant to CAA section 112(d)(6), we conducted a technology review
that focused on identifying and evaluating developments in practices,
processes, and control technologies for sources of HAP in the Mineral
Wool Production source category. As discussed in the 2011 proposal (76
FR 72798), existing cupolas are controlled using baghouses, and bonded
lines are controlled using thermal oxidizers. We did not identify any
relevant cost-effective developments in technologies, practices, or
processes since promulgation of the 1999 NESHAP that would further
reduce HAP emissions. Therefore, we did not propose any changes to the
1999 NESHAP as a result of our technology review under CAA section
112(d)(6) for the Mineral Wool Production source category. Additional
information regarding the technology review for the Mineral Wool
Production source category can be found in the document titled,
``Section 112(d)(6) Technology Review for the Final Mineral Wool
NESHAP'' available in the docket for this action (EPA-HQ-OAR-2010-
1041).
2. How did the technology review change for the Mineral Wool Production
source category?
    We have not changed any aspect of the technology review for this
source category since the November 2014 supplemental proposal.
3. What key comments did we receive on the technology review, and what
are our responses?
    The comments received on our technology review and findings were
generally supportive. A summary of the comments received regarding the
technology review and our responses can be found in the comment summary
and response document available in the docket for this action (EPA-HQ-
OAR-2010-1041). We note that none of the public comments and
information received in response to the November 2014 supplemental
proposal provided data relevant to the technology review, and we made
no changes to the technology review based on the comments.
4. What is the rationale for our final approach for the technology
review?
    As explained in the various proposals and in section IV.B.1 of this
preamble, we did not identify any cost-effective developments in
practices, processes and controls used to reduce emissions from the
mineral wool production industry. Therefore, consistent with our
proposals, we are not making any changes to the standards as a result
of the CAA section 112(d)(6) review.

C. MACT Standards for Pollutants Previously Regulated Under a Surrogate
and Previously Unregulated Pollutants

1. What did we propose pursuant to CAA section 112(d)(2) and (3) for
pollutants previously regulated under a surrogate and for previously
unregulated pollutants?
    In our November 2011 proposal, we proposed revisions to the 1999
NESHAP under CAA sections 112(d)(2) and (3). We proposed to remove
unreasonable surrogates, to set limits for each HAP emitted that was
previously regulated under a surrogate, and to set limits for
previously unregulated HAP. These revisions included removing CO as a
surrogate for COS and removing formaldehyde as a surrogate for methanol
and phenol; proposing emission limits for COS from cupolas,
formaldehyde, methanol, and phenol from combined collection and curing
operations; and proposing emissions limits for previously unregulated
pollutants (i.e., HCl and HF emitted from cupolas).
    In our April 2013 supplemental proposal, we made changes to the
previously proposed emission limits for phenol, formaldehyde, and
methanol based on new emissions test data. We further proposed
subcategories for COS emissions from cupolas based on cupola design.
Finally, we proposed subcategories for HF and HCl from cupolas based on
whether they processed slag.
    In the November 2014 supplemental proposal, we revised emission
limits under CAA sections 112(d)(2) and (3) for cupolas and bonded
lines as a result of new information regarding detection limits (and
consistent with our procedures for ensuring that emission limits are
not set below the minimum level that can be accurately measured), new
source test data and our approach for calculating MACT floors based on
limited data sets.
2. How did we change our proposed emission limits for pollutants that
were previously regulated under a surrogate or that were previously
unregulated?
    Our final emission limits for pollutants previously regulated under
a surrogate, and previously unregulated pollutants did not change since
our most recent proposal in November 2014.
3. What key comments did we receive on pollutants previously regulated
under a surrogate and on previously unregulated pollutants?
    We received comments both supporting and objecting to our use of
the UPL in calculating MACT floors and the way we treat limited
datasets for these pollutants. The commenters did not provide new
information or a basis for the EPA to change the proposed emission
limits, and did not show that facilities cannot comply with the MACT
standards. The comments related to the proposed emission limits for
pollutants that were previously regulated under a surrogate and that
were previously unregulated are in the comment summary and the response
document available in the docket for this action (EPA-HQ-OAR-2010-
1041).

4. What is the rationale for our final approach for pollutants
previously regulated under a surrogate and for previously unregulated
pollutants?
    As we discussed in the preamble for the November 2014 supplemental
proposal and provided in the comment summary and response document
available in the docket, we are finalizing, as proposed, the emission
limits for pollutants previously regulated under a surrogate and for
previously unregulated pollutants. Three surrogate relationships were
in place in the Mineral Wool MACT standard, and we reviewed each of
these to determine whether they were reasonable surrogates. We found
that the relationship of formaldehyde, methanol and phenol emissions
tend to be specific to the binder formulation of an individual product.
We found that the surrogacy of CO for COS was not reasonable because
the two pollutants are not invariably present and the relationships
tend to be specific to the site. We retained the surrogacy of PM for
non-mercury HAP metals because control of PM achieves the same level of
control for non-mercury HAP metals, regardless of the concentration of
those metals in the PM or whether the concentration of those metals
varies in the PM.
    We requested and obtained HAP-specific emissions testing for all
HAP emitted by all processes in the mineral wool industry. Emissions of
PM, HF, HCl, and COS were measured from at least one cupola in
operation at each facility, and emissions of formaldehyde, methanol,
and phenol were measured at the three bonded lines that were in
operation in 2010. As a result of the information we gathered, we are
finalizing limits for all measured HAP and for the collection process,
which emits HAP but was not regulated under the 1999 MACT standard. We
are not changing the PM emission limit as a result of the information
we gathered.
    HF and HCl were not previously regulated, and the emissions of
these pollutants depend upon whether slag is used in the cupola. Slag
is a raw material in the mineral wool industry that is a waste product
of electric arc furnaces at steel plants. Depending on the end-use of
the mineral wool product, slag is a needed ingredient in some mineral
wool formulations and an undesirable ingredient in others. The use of
slag as a raw material in the mineral wool cupola causes ``shot''
(small pellets of iron) to form in the mineral wool product. The
quality of some mineral wool products (such as that used for hydroponic
gardening) is affected by the presence of shot, and, as a result,
facilities making such products do not use slag in their raw materials.
Consequently, their emissions of HF and HCl are lower. Two
subcategories of cupolas reflect whether slag is processed in the
cupola.
    Emissions of COS are affected by whether a cupola is designed as a
closed cupola (which results in lower COS emissions) or an open cupola
(which results in higher COS emissions). Two subcategories of cupolas
reflect this design criteria.
    Data collected from the mineral wool industry showed three bonded
lines were in operation at the time of data collection in 2010. The
bonded lines include both collection (the process in which the fibers
are formed and sprayed with a phenol/formaldehyde binding agent); and
curing, the thermosetting process that cures the binder. Collection was
not regulated under the 1999 MACT standard, the emissions from both the
curing and collection processes are vented to the same line, and the
emissions from these processes can be measured together. These combined
collection and curing operations emit phenol, formaldehyde, and
methanol as a result of the phenolic resin used to produce the bonded
product. We are finalizing limits for combined collection and curing
operations according to three different designs: Vertical, horizontal,
and drum. The final emission limits for the mineral wool industry are
shown above in Table 2 of section III of this preamble.

D. Startup, Shutdown, and Malfunction Provisions for the Mineral Wool
Production Source Category

1. What SSM provisions did we propose for the Mineral Wool Production
source category?
    In its 2008 decision in Sierra Club v. EPA, 551 F.3d 1019 (D.C.
Cir. 2008), the United States Court of Appeals for the District of
Columbia Circuit vacated portions of two provisions in the EPA's CAA
section 112 regulations governing the emissions of HAP during periods
of SSM. Specifically, the Court vacated the SSM exemption contained in
40 CFR 63.6(f)(1) and 40 CFR 63.6(h)(1), holding that under section
302(k) of the CAA, emissions standards or limitations must be
continuous in nature and that the SSM exemption violates the CAA's
requirement that some CAA section 112 standards apply continuously.
    We have therefore eliminated the SSM exemption in this rule.
Consistent with Sierra Club v. EPA, the EPA has established work
practice standards for those periods. We also revised Table 1 of the
General Provisions applicability table in several respects as is
explained in more detail below. For example, we have eliminated the
incorporation of the General Provisions' requirement that the source
develop an SSM plan. We also eliminated and revised certain
recordkeeping and reporting provisions that are related to the SSM
exemption as described in detail in the proposed rule and summarized
again in section IV.D of this preamble, in the rule at 40 CFR 63.1389,
and in the General Provisions Table 1 to subpart DDD of part 63 (40 CFR
part 63, subpart A).
2. How did the SSM provisions change for the Mineral Wool Production
source category?
    We have not changed any aspect of the proposed SSM provisions since
the November 2014 supplemental proposal.
3. What key comments did we receive on the SSM provisions, and what are
our responses?
    We received comments regarding the proposed revisions to remove the
SSM exemptions for the Mineral Wool Production source category.
Comments from industry representatives expressed support for the
proposed work practice standards. Another commenter contended that we
should have established numerical emission limits. As we noted in the
November 2014 supplemental proposal (79 FR 68016), the EPA may
promulgate a work practice rather than an emissions standard when
measurement of the emissions is technically and economically
practicable. In the case of this source category, emissions are not at
steady state during startup and shutdown (a necessary factor for
accurate emissions testing), and the varying stack conditions, gas
compositions, and flow rates make accurate emission measurements
impracticable. In addition, startup period for mineral wool cupolas,
typically 2 hours, is too short a time to conduct source testing.
    The commenters did not provide new information or a basis for the
EPA to change the proposed provisions and did not show that facilities
cannot comply with the work practice standards during periods of
startup and shutdown. The comments related to the proposed revisions to
remove the SSM exemptions and our specific responses to those comments
can be found in the comment summary and response document available in
the docket for this action (EPA-HQ-OAR-2010-1041).

4. What is the rationale for our final decisions for the SSM
provisions?
    For the reasons provided above, in the preamble for the proposed
rule and provided in the comment summary and response document
available in the docket, we have removed the SSM exemption from the
Mineral Wool Production NESHAP; eliminated or revised certain
recordkeeping and reporting requirements related to the eliminated SSM
exemption; and removed or modified inappropriate, unnecessary, or
redundant language in the absence of the SSM exemption. For periods of
startup and shutdown, we are finalizing the work practices of the best
performers, as proposed in the November 2014 supplemental proposal.
Owners/operators may choose to comply using two potential options
during startup and shutdown. One, cupola emissions may be controlled
using the control devices that meet the limits of the standard during
normal operation, or two, the cupola may be operated during startup and
shutdown with 3 percent or more excess oxygen. Additionally, sources
must maintain records of the startup and shutdown option they practice,
and must monitor and keep records of the parameters of the operating
control device(s) or the oxygen level of the cupola during these
periods. The controls of startup and shutdown emissions practiced by
the best performers in the source category are sufficient so that no
additional standards are needed to address emissions during startup or
shutdown periods.

E. Other Changes Made to the Mineral Wool Production NESHAP

1. What other changes did we propose for the Mineral Wool Production
NESHAP?
a. Electronic Reporting
    As stated in the preamble to the November 2011 proposed rule, the
EPA proposed electronic reporting requirements. See section III.G of
this preamble for more information on what we proposed (and what we are
finalizing) for electronic reporting.
b. Test Methods and Testing Frequency
    We are finalizing, as proposed, the requirement for new sources to
conduct performance tests to demonstrate compliance with the emission
limits for cupolas and combined collection/curing operations within 180
days of the applicable compliance date and every 5 years thereafter. We
are finalizing, as proposed, the requirement for existing sources to
conduct performance tests to demonstrate compliance with the emission
limits for cupolas and combined collection/curing operations by July
30, 2018 and every 5 years thereafter. We are finalizing, as proposed,
the addition of EPA Methods 26A and 320 in appendix A of part 63 for
measuring the concentrations of HCl and HF; and EPA Method 318 for
measuring the concentrations of COS, formaldehyde, methanol, and
phenol. In addition, we are finalizing editorial changes to the
performance testing and compliance procedures to replace references in
the 1999 NESHAP to the surrogates CO and formaldehyde with references
to specific HAP (formaldehyde, methanol, and phenol for the surrogate
formaldehyde, and COS for the surrogate CO).
2. How did the provisions regarding these other changes to the Mineral
Wool Production NESHAP change since proposal?
    We have not made any changes to the proposed provisions for
electronic reporting; testing methods and frequency; definitions or
revisions to the General Provision applicability table.
3. What key comments did we receive on the other changes to the Mineral
Wool Production NESHAP, and what are our responses?
    We received no key comments regarding electronic reporting, testing
methods and frequency, definitions, and revisions to the General
Provisions applicability table. A summary of the comments we did
receive and our responses can be found in the comment summary and
response document available in the docket for this action (EPA-HQ-OAR-
2010-1041).
4. What is the rationale for our final decisions regarding these other
changes to the Mineral Wool Production NESHAP?
    There was no information in the public comments that affected the
rationale for these provisions that was presented in the various
proposals. Therefore, we are finalizing the proposed provisions
regarding electronic reporting; testing methods and frequency;
definitions and revisions to the General Provision applicability table.

V. What is included in the Final Wool Fiberglass Manufacturing Rule for
major sources?

    This action finalizes the EPA's determinations pursuant to the RTR
provisions of CAA section 112 for the Wool Fiberglass Manufacturing
source category and amends the Wool Fiberglass Manufacturing NESHAP
based on those determinations. This action also finalizes other changes
to the NESHAP (e.g., compliance dates) as discussed in section V.F of
this preamble. In addition, we are finalizing the emission limits for
major sources in the Wool Fiberglass Manufacturing source category as
shown in Table 3 of this preamble.

Table 3--Emission Limits for Wool Fiberglass Manufacturing Major Sources
                     [lb pollutant/ton glass pulled]
------------------------------------------------------------------------
              Process                        HAP          Emission limit
------------------------------------------------------------------------
Existing Flame Attenuation Lines..  Formaldehyde........             5.6
                                    Phenol..............             1.4
                                    Methanol............            0.50
New Flame Attenuation Lines.......  Formaldehyde........             2.6
                                    Phenol..............            0.44
                                    Methanol............            0.35
Existing and New Furnaces.........  PM..................            0.33
Existing and New Gas-Fired          Chromium compounds..         0.00025
 Furnaces.
------------------------------------------------------------------------

A. What are the final rule amendments based on the risk review for the
Wool Fiberglass Manufacturing (major sources) source category?

    Pursuant to CAA section 112(f)(2), we are finalizing emission
limits for chromium emissions from gas-fired glass-melting furnaces of
0.00025 pounds of total chromium per ton of glass pulled to provide an
ample margin of safety to protect public health. We are also requiring
that facilities establish the materials mix, including the percentages
of raw materials and cullet, used in gas-fired glass-melting furnaces
during the performance test conducted to demonstrate compliance with
the chromium emission limit. We are requiring that the percentage of
cullet in the material mix be continually maintained at or below the
level established during the most recent performance test showing
compliance with the standard.
    We note that although we have adopted these same standards, under
both CAA sections 112(f)(2) and 112(d)(6), these standards rest on
independent statutory authorities and independent rationales.
Consequently, these standards remain independent and legally severable.

B. What are the final rule amendments based on the technology review
for the Wool Fiberglass Manufacturing (major sources) source category?

    We determined that there are developments in practices, processes,
and control technologies that warrant revisions to the MACT standards
for this source category. Therefore, to satisfy the requirements of CAA
section 112(d)(6), we are revising the existing MACT standards to
include an emission limit for glass-melting furnaces of 0.33 pounds of
PM per ton of glass pulled as we proposed in April 2013. In this
action, we are also revising the proposed chromium emission limit for
gas-fired glass-melting furnaces from 0.00006 to 0.00025 pounds of
total chromium per ton of glass pulled, based on our re-assessment of
emissions data for newly-rebuilt gas-fired glass-melting furnaces.
    We note that although we have adopted the total chromium compounds
standards under both CAA sections 112(f)(2) and 112(d)(6), these
standards rest on independent statutory authorities and independent
rationales. Consequently, these standards remain independent and
legally severable.

C. What are the final rule amendments pursuant to CAA sections
112(d)(2) and (3) for the Wool Fiberglass Manufacturing (major sources)
source category?

    This action finalizes the HAP-specific limits proposed in November
2014 that we developed under CAA sections 112(d)(2) and (3) as a result
of removing the use of formaldehyde as a surrogate for methanol and
phenol on FA lines. We are also eliminating the subcategories for FA
lines because the technical bases for distinguishing the subcategories
when the original rule was developed no longer exist and we are
promulgating emission limits at the MACT floor level for formaldehyde,
methanol, and phenol.
    As explained in section V.H of this preamble, we are not, at this
time, finalizing limits under CAA sections 112(d)(2) and (3) for RS
lines.

D. What are the final rule amendments pursuant to CAA section 112(h)
for the Wool Fiberglass Manufacturing (major sources) source category?

    This action finalizes the work practice standards for HCl and HF
emissions from glass-melting furnaces at wool fiberglass manufacturing
facilities developed under CAA section 112(h) as proposed in November
2014 (79 FR 68023). These amendments to the Wool Fiberglass
Manufacturing NESHAP are consistent with the amendments discussed in
the November 2014 supplemental proposal.

E. What are the final rule amendments for the Wool Fiberglass
Manufacturing (major sources) source category addressing emissions
during periods of startup and shutdown?

    We are finalizing, as proposed, changes to the Wool Fiberglass
Manufacturing NESHAP to eliminate the SSM exemption. Consistent with
Sierra Club v. EPA, 551 F. 3d 1019 (D.C. Cir. 2008), the EPA has
established work practice standards in this rule that apply during
startup and shutdown periods. We are revising Table 1 to subpart NNN of
part 63 (General Provisions applicability table) to change several
references related to requirements that apply during periods of SSM. We
also eliminated or revised certain recordkeeping and reporting
requirements related to the eliminated SSM exemption. We are specifying
that items of equipment that are required or utilized for compliance
with 40 CFR part 63, subpart NNN must be operated during startup and
shutdown. We are finalizing the specifications designating when startup
and shutdown begins and recordkeeping requirements for demonstrating
compliance during startup and shutdown periods.
    We determined that facilities in this source category can meet the
applicable work practice standards by following the startup and
shutdown procedures that we identified as representative of the
procedures employed by the best performing units during periods of
startup and shutdown.
    Gas-fired furnaces use an electrostatic precipitator (ESP) to
control emissions during normal operations. The best performing gas-
fired furnaces route emissions during startup and shutdown to the
control device. We note that operators of gas-fired furnaces that
formerly turned off the controls during startup or shutdown would no
longer be allowed to do so.
    Electric furnaces use baghouses to control emissions during normal
operations. Until the crust is formed on top of the molten glass (and
startup ends) the temperature of the gases that would be routed to the
baghouse would cause the bags to catch fire. The best performing
electric furnaces use only cullet (which emits PM at extremely low
levels when melted) and clean fuels (natural gas, which does not emit
PM when combusted) during startup and shutdown in order to minimize PM
emissions during these periods.

F. What other changes have been made to the Wool Fiberglass
Manufacturing NESHAP (major sources)?

    We are finalizing, as proposed, the addition of EPA Method 29 for
measuring the concentrations of chromium. We are finalizing the
requirement, as proposed, to maintain the filter temperature at 248
 25 [deg]F when using Method 5 to measure PM emissions from
furnaces. We are also amending the NESHAP to allow owners or operators
to measure PM emissions from furnaces using either EPA Method 5 or
Method 29.
    We are finalizing, as proposed, the addition of EPA Method 318 as
an alternative test method for measuring the concentration of phenol
and methanol and EPA Method 308 as an alternative test method for
measuring the concentration of methanol. We are finalizing, as proposed
in the 2013 supplemental proposal (78 FR 22402), the replacement of a
minimum sampling time of 1 hour with the specification to collect 10
spectra when using EPA Method 318. When using Method 316 to measure
formaldehyde, we are finalizing, as proposed, the requirement to
collect a minimum sampling volume of 2 dry standard cubic meters
(dscm); however, we are not finalizing the

proposed minimum sampling run time of 2 hours. We are also finalizing
editorial changes to the performance testing and compliance procedures
to specify formaldehyde, methanol, phenol (rather than the surrogate,
formaldehyde), chromium, HCl, and HF. Additionally, for existing
sources we are finalizing, as proposed, the requirement to conduct
performance tests to demonstrate compliance with the chromium emission
limit for furnaces no later than July 31, 2017 and annually thereafter;
to demonstrate compliance with the PM emission limit for furnaces no
later than July 31, 2017 and every 5 years thereafter; and to
demonstrate compliance with the phenol, formaldehyde and methanol
emission limits for FA lines no later than July 31, 2017 and every 5
years thereafter.
    We are finalizing the requirement for new sources to comply with
the emission limits on July 29, 2015, or upon the initial startup,
whichever is later, and to conduct performance tests to demonstrate
compliance with the emission limits for furnaces and FA lines no later
than 180 days after the applicable compliance date. Following the
initial test to demonstrate compliance with the chromium emission
limit, owners or operators must test for chromium emissions annually.
For all other pollutants, owners or operators must conduct performance
tests every 5 years after the initial test to demonstrate compliance
with the emissions limits. Table 4 of this preamble summarizes the
compliance test schedule for major and area sources.

                Table 4--Wool Fiberglass Manufacturing Compliance Test Schedule for Major Sources
----------------------------------------------------------------------------------------------------------------
                                                                Initial test dates
             Process                 Pollutant(s)    ---------------------------------------- Subsequent testing
                                                       Existing sources       New sources          frequency
----------------------------------------------------------------------------------------------------------------
FA Line.........................  Phenol              2 years after       Within 180 days     Every 5 years
                                   Formaldehyde        publication of      after publication   thereafter.
                                   Methanol.           the final rule      in the Federal
                                                       amendments in the   Register, or 180
                                                       Federal Register.   days after
                                                                           initial startup,
                                                                           whichever is
                                                                           later.
All Furnace Types...............  PM
Gas-fired Furnace...............  Chromium compounds                                          Annually
                                                                                thereafter.
----------------------------------------------------------------------------------------------------------------

    We are finalizing, as proposed, the clarification that 40 CFR part
63, subpart NNN applies to FA lines, regardless of what products are
manufactured on the FA line.
    In this action, we are finalizing, as proposed, definitions for
``gas-fired glass-melting furnace'' and ``incinerator.'' We are also
revising the definition of ``new source'' and the trigger date for the
requirement to submit notifications of intent to construct/reconstruct
an affected source to reflect the date of the initial RTR proposal
(November 25, 2011).
    We are finalizing, as proposed, the monitoring requirement for
furnaces and FA lines to provide flexibility in establishing an
appropriate monitoring parameter.
    We are also making minor corrections to the citations in Table 1
(part 63 General Provision applicability table) to reflect the final
amendments in this action, and the revisions that have been made to the
General Provisions since 1999.

G. What are the effective and compliance dates of the standards?

    The revisions to the MACT standards for the Wool Fiberglass
Manufacturing source category being promulgated in this action are
effective on July 29, 2015. The compliance date for existing sources is
July 31, 2017. New sources must comply with the all of the standards
immediately upon the effective date of the standard, July 29, 2015, or
upon initial startup, whichever is later.
    The effective and compliance dates finalized in this action are
consistent with the dates we presented in the 2014 supplemental
proposal.

H. What is the status of the Wool Fiberglass Manufacturing MACT
standard amendments under CAA sections 112(d)(2) and (3) for RS
Manufacturing Lines?

    We are not finalizing the formaldehyde, methanol, and phenol
standards under CAA sections 112(d)(2) and (3) for RS manufacturing
lines in this final action. On November 25, 2011 (76 FR 72791), we
proposed to discontinue use of formaldehyde as a surrogate for phenol
and methanol and we proposed formaldehyde, methanol and phenol emission
limits for RS and FA lines. On April 15, 2013 (72 FR 22387), we
proposed revised emission limits for RS lines based on clarification of
test data received from the industry during the comment period. We
explained that since the 1999 promulgation of the MACT standards, many
companies had discontinued the use of formaldehyde. However, they did
not distinguish between the bonded lines that still used formaldehyde
and those that did not. We had, therefore, included some data for HAP-
free lines along with the data for lines still using formaldehyde when
we developed the emission limits proposed in the November 2011 proposal
(78 FR 22387). In the November 2014 supplemental proposal (79 FR
68203), we also proposed revised formaldehyde, methanol, and phenol
emission limits for new RS lines as a result of our updated approach
for evaluating limited datasets (79 FR 68023-24).
    The EPA is not finalizing these proposed CAA sections 112(d)(2) and
(3) standards in this action because we believe the data that we relied
on in proposing these standards are not sufficiently related to current
operations or emissions from RS bonded lines. The emissions and process
data available to EPA were collected beginning in 2003. As previously
explained, since that time, sources have phased out the use of a
phenol/formaldehyde binder from approximately 95 percent of the lines
on which it was previously used. We have also found out that sources
often can no longer either identify the products that were tested or on
the lines on which those products had been manufactured. Moreover, when
sources can identify the products that were tested, those products are
now produced using a HAP-free binder, and the product lines that now
operate using a phenol/formaldehyde binder do not bear similarity in
size, end use, production rate or loss on ignition (LOI) percent to the
tested product line. As a result, the data no longer represent current
industry conditions, most notably the significant reduction in the use
of phenol/formaldehyde binders in wool fiberglass manufacturing.
Consequently, we have issued a CAA section 114 ICR to wool fiberglass
facilities to obtain updated formaldehyde, methanol, and

phenol emissions and process data for RS manufacturing lines.

I. What are the requirements for submission of performance test data to
the EPA for the Wool Fiberglass Manufacturing NESHAP?

    The requirements for electronic reporting of performance test data
for wool fiberglass manufacturing major sources are the same as the
requirements for the mineral wool production source category. See
section III.G of this preamble for a description of the requirements.

VI. What is the rationale for our final decisions and amendments for
the Wool Fiberglass Manufacturing source category (major sources)?

    For each issue, this section provides a description of what we
proposed and what we are finalizing for the issue, the EPA's rationale
for the final decisions and amendments and a summary of key comments
and responses. For all comments not discussed in this preamble, comment
summaries and the EPA's responses can be found in the comment summary
and response document available in Docket ID No. EPA-HQ-OAR-2010-1042.

A. Residual Risk Review for the Wool Fiberglass Manufacturing Source
Category (Major Sources)

1. What did we propose pursuant to CAA section 112(f) for the Wool
Fiberglass Manufacturing source category (major sources)?
    Pursuant to CAA section 112(f)(2), we conducted a residual risk
assessment and presented the results of this assessment, along with our
proposed decisions regarding risk acceptability and ample margin of
safety, in the November 2011 proposed rule (76 FR 72801). Based on the
inhalation risk assessment, we estimated that the MIR could be as high
as 40-in-1 million due to actual emissions and up to 60-in-1 million
due to MACT-allowable emissions, mainly due to formaldehyde and
hexavalent chromium emissions. We stated that the risk levels due to
actual and MACT-allowable emissions were acceptable; however, we
proposed an emission limit for total chromium (0.00006 pounds per ton
of glass pulled) in order to provide an ample margin of safety to
protect public health.
    In the April 2013 supplemental proposal, we revised the draft risk
assessment to reflect new emissions data for hexavalent chromium that
we collected from all glass-melting furnaces available for testing in
response to our October 28, 2011, CAA section 114 ICR. These revisions
reduced our estimate of risk from actual emissions when compared to the
risk assessment conducted for the November 2011 proposal. The risk from
wool fiberglass manufacturing was driven by formaldehyde and hexavalent
chromium. The MIR for actual baseline emissions decreased from 40-in-1-
million to 20-in-1 million (formaldehyde), with the acute noncancer HQ
remaining at 30 for the REL and at 2 for the AEGL-1 (formaldehyde). The
maximum chronic non-cancer TOSHI value based on actual emissions
remained at 0.2 with emissions of formaldehyde dominating those
impacts, indicating no significant potential for chronic noncancer
impacts.
    In the November 2014 supplemental proposal, we presented the
revised draft risk assessment to reflect updates to the model and model
libraries and also retained the proposed emission limits for chromium
compounds for existing and new gas-fired glass-melting furnaces. These
revisions did not significantly change our estimate of risk from actual
emissions when compared to the risk assessment conducted for the April
2013 supplemental proposal (79 FR 68020). The risk from wool fiberglass
manufacturing was driven by formaldehyde and hexavalent chromium and
continued to be well within a level we consider to be acceptable. The
MIR for actual baseline emissions remained 20-in-1 million
(formaldehyde), with the acute noncancer HQ remaining at 30 for the REL
and decreased from 2 to 1 for the AEGL-1 (formaldehyde). The maximum
chronic non-cancer TOSHI value based on actual emissions decreased from
0.2 to 0.1 with emissions of formaldehyde dominating those impacts,
indicating no significant potential for chronic noncancer impacts.
Overall, we considered the risk to be acceptable.
    Based on information provided by the industry, 95 percent of the RS
lines no longer use phenol-formaldehyde binders and are no longer major
sources. However, this phase out is not reflected in the facility file
data on which the risk assessment was based. Throughout the wool
fiberglass manufacturing industry, these binders continued to be phased
out as this rule was developed. The risk analysis we conducted for the
Wool Fiberglass Manufacturing source category overstates the risk
because of the continuing phase out. Therefore, we believe the risks
from wool fiberglass manufacturing from actual emissions are lower than
the risks we estimated.
2. How did the risk review change for the Wool Fiberglass Manufacturing
source category (major sources)?
    The baseline risk assessment has not changed since the November
2014 supplemental proposal. The MIR based on actual emissions remains
at 20-in-1 million with the acute noncancer HQ remaining at 30 for the
REL and 1 for the AEGL-1 (formaldehyde). The maximum chronic non-cancer
TOSHI value based on actual emissions is 0.1 with emissions of
formaldehyde dominating those impacts, indicating no significant
potential for chronic noncancer impacts.
    The MIR based on MACT-allowable emissions could be as high as 60-
in-1 million, which we believe to be a conservative estimate based on
four factors: (1) At one time, there were at least 60 RS lines in the
industry, (2) industry has stated that 95 percent of RS lines no longer
use formaldehyde as a binder, (3) Industry has stated that there are
only 5 RS lines left that use a phenol/formaldehyde binder, and (4)
Title V permit records indicate that 20 out of a total of 30 facilities
have completely phased out their use of formaldehyde as a raw material
throughout the facility.
    We conducted a new assessment of the risks remaining after
implementation of these final rule revisions. The revised assessment of
post-control risks reflects the adjustment of the chromium compounds
emission limit and the EPA's deferral of setting standards for
formaldehyde, methanol and phenol from RS lines. Specifically, the risk
assessment takes into account the change in the chromium compounds
emission limit for gas-fired glass-melting furnaces from 0.00006 pounds
of chromium per ton of glass pulled to 0.00025 pounds of chromium per
ton of glass pulled, the emission limits for formaldehyde at new and
existing FA lines (2.6 pounds per ton and 5.6 pounds per ton,
respectively) and the current emission estimates for formaldehyde,
methanol and phenol from RS lines. The MIR for cancer after
implementation of the RTR could be up to 60-in-1 million (equal to the
current risk estimates for allowables) but, as discussed above, this is
a conservative, upper-end estimate. Consequently, we believe risks are
significantly lower than estimated and the standards provide an ample
margin of safety.
    Emissions of chromium compounds are a secondary risk driver to
formaldehyde, and the risk is 7-in-1 million based on current actual
emissions. It is important to note that,

even though risks are acceptable, the health risks from hexavalent
chromium emissions from wool fiberglass manufacturing facilities could
be much higher in the future without a chromium compounds emission
limit. To capture this scenario, we conducted an auxiliary risk
analysis in which we assumed all wool fiberglass furnaces emitted
hexavalent chromium at the same rate as the reasonable highest-emitting
furnace. The results of the auxiliary risk analysis showed that, in the
absence of a chromium emission limit and with furnaces emitting at the
assumed emission rate, risk at four facilities is expected to increase
over time to greater than 100-in-1 million, due to increasing chromium
emissions occurring with furnace age. Therefore, we determined that the
chromium emission limit in the final rule, which will limit the MIR
cancer risk from hexavalent chromium emissions from this category to no
higher than 3-in-1 million, is necessary to provide an ample margin of
safety.
    Regarding chromium compounds, as discussed above, we received
comments on the proposed chromium compounds limit that indicated that a
newly-rebuilt furnace, which we believe is the likely compliance
technology, may not be able to demonstrate compliance with the proposed
emission limit. The comment was based on one specific example from the
2012 test data that showed a 1-year old gas-fired glass-melting furnace
emitting approximately 0.0002 pounds chromium per ton of glass. We re-
evaluated the proposed chromium compounds limit in light of information
on this technology, and based on the data available, we have revised
the chromium compounds limit and are now finalizing an emissions limit
of 0.00025 pounds per ton of glass pulled for gas-fired glass-melting
furnaces. We conducted an assessment of the risk attributable to all
HAP for each facility and determined that increasing the chromium
compound emission limit from 0.00006 to 0.00025 pounds total chromium
per ton of glass pulled has a minimal effect on the post-RTR risks
because these risks are largely driven by formaldehyde emissions.
Specifically, at the chromium compounds emission limit of 0.00025
pounds total chromium per ton of glass pulled, the MIR due to only
chromium emissions for the source category is 3-in-1 million.
    The results of the risk assessment are presented in more detail in
the final residual risk memorandum titled ``Residual Risk Assessment
for the Mineral Wool Production and Wool Fiberglass Manufacturing
Source Categories in Support of the June 2015 Final Rule,'' which can
be found in Docket ID No. EPA-HQ-OAR-2010-1042.
3. What key comments did we receive on the risk review for Wool
Fiberglass Manufacturing (major sources), and what are our responses?
    We received comments in support of and against our proposed
determination of risk acceptability, ample margin of safety analysis,
and requirement for additional control. A summary of these comments and
our responses can be found in the comment summary and response document
available in the docket for this action (EPA-HQ-OAR-2010-1042). The
following is a summary of the key comments received regarding the risk
assessment for the Wool Fiberglass Manufacturing source category and
our responses to these comments. Additional comments on the risk
assessment and our responses can be found in the comment summary and
response document available in the docket for this action (EPA-HQ-OAR-
2010-1042).
    Comment: One commenter stated that the EPA should find the acute
health risk from wool fiberglass manufacturing facilities to be
unacceptable. The commenter noted that the EPA's assessment in the
November 2011 proposal found an acute risk of 30 for the Wool
Fiberglass Manufacturing source category and argued that the EPA should
find the health risk to be unacceptable under CAA section 112(f)(2)
based on this acute risk.
    The commenter stated that the EPA has a presumption that an HQ
below 1 is safe, that the EPA has stated that a HQ less than or equal
to 1 indicates that adverse noncancer effects are not likely to occur,
and that exposure below that threshold level is safe. The commenter
added that the EPA did not adequately explain why the formaldehyde
risks were found to be acceptable although they are 30 times higher
than the threshold.
    The commenter asserted that, by applying the outdated integrated
risk information system (IRIS) dose-response values in determining
formaldehyde inhalation exposure risk, the EPA is not basing the
proposed rule on the best available science. The commenter urged the
EPA to revise the proposed rule to accurately convey the best available
science and a weight-of-evidence approach in compliance with the
Information Quality Act (IQA) Guidelines and Executive Order 13563. In
particular, the commenter argued that the EPA should reject the 1991
IRIS dose-response value and incorporate the Chemical Industry
Institute of Toxicology (CIIT, 1999) cancer dose-response value for
formaldehyde.
    Response: As discussed in sections V.A and VI.A of this preamble,
we revised the risk assessment for wool fiberglass facilities for the
November 2014 supplemental proposal. For wool fiberglass facilities,
the MIR for actual baseline emissions remained 20-in-1 million
(formaldehyde), with the acute noncancer HQ remaining at 30 for the REL
and decreased from 2 to 1 for the AEGL-1 (formaldehyde). The maximum
chronic non-cancer TOSHI value based on actual emissions decreased from
0.2 to 0.1 with emissions of formaldehyde dominating those impacts,
indicating no significant potential for chronic noncancer impacts. We
found that the risks were acceptable.
    We note that the acute risks are based on an REL value, which is
defined as ``the concentration level at or below which no adverse
health effects are anticipated for specified exposure duration.''
Moreover, we note that the acute risk assessment is a worst-case
assessment. For example, the acute assessment assumes worst-case
meteorology, peak emissions and an individual being located at the site
of maximum concentration for an hour. Taken together, the EPA does not
believe that in all RTR reviews, HQ values must be less than or equal
to 1. Rather, the EPA finds that acute risks must be judged on a case-
by-case basis in the context of all the available health evidence and
risk analyses.
    To better characterize the potential health risks associated with
estimated acute exposures to HAP, and in response to a key
recommendation from the Science Advisory Board's (SAB) peer review of
the EPA's RTR risk assessment methodologies,\6\ we generally examine a
wider range of available acute health metrics (e.g., RELs, AEGLs) than
we do for our chronic risk assessments. This is in response to the
SAB's acknowledgement that there are generally more data gaps and
inconsistencies in acute reference values than there are in chronic
reference values. In some cases, when Reference Value Arrays \7\ for
HAP have been developed, we consider additional acute values (i.e.,
occupational and

international values) to provide a more complete risk characterization.
The EPA uses AEGL and Emergency Response Planning Guidelines (ERPG)
values (when available) in conjunction with REL values (again, when
available) to characterize potential acute health risks. However, it is
often the case that HAP do not have all of these acute reference
benchmark values. In these instances, the EPA describes the potential
acute health risk in relation to the acute health values that are
available. Importantly, when interpreting the results, we are careful
to identify the benchmark being used and the health implications
associated with any specific benchmark being exceeded. By definition,
the acute California reference exposure level (CA-REL) represents a
health-protective level of exposure, with no risk anticipated below
those levels, even for repeated exposures; however, the health risk
from higher-level exposures is unknown. Therefore, when a CA-REL is
exceeded and an AEGL-1 or ERPG-1 level is available (i.e., levels at
which mild effects are anticipated in the general public for a single
exposure), we have used them as a second comparative measure.
Historically, comparisons of the estimated maximum off-site 1-hour
exposure levels have not been typically made to occupational levels for
the purpose of characterizing public health risks in RTR assessments.
This is because occupational ceiling values are not generally
considered protective for the general public since they are designed to
protect the worker population (presumed healthy adults) for short
duration (i.e., less than 15 minute) increases in exposure. As a
result, for most chemicals, the 15-minute occupational ceiling values
are set at levels higher than a 1-hour AEGL-1, making comparisons to
them irrelevant unless the AEGL-1 or ERPG-1 levels are exceeded. Such
is not the case when comparing the available acute inhalation health
effect reference values for formaldehyde.\8\
---------------------------------------------------------------------------

    \6\ The SAB peer review of RTR Risk Assessment Methodologies is
available at: http://yosemite.epa.gov/sab/sabproduct.nsf/
4AB3966E263D943A8525771F00668381/$File/EPA-SAB-10-007-unsigned.pdf.
    \7\ U.S. EPA. (2009) Chapter 2.9 Chemical Specific Reference
Values for Formaldehyde in Graphical Arrays of Chemical-Specific
Health Effect Reference Values for Inhalation Exposures (Final
Report). U.S. EPA, Washington, DC, EPA/600/R-09/061, and available
on-line at: http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=211003.
    \8\ U.S. EPA. (2009) Chapter 2.9 Chemical Specific Reference
Values for Formaldehyde in Graphical Arrays of Chemical-Specific
Health Effect Reference Values for Inhalation Exposures (Final
Report). U.S. EPA, Washington, DC, EPA/600/R-09/061, and available
on-line at: http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=211003.
---------------------------------------------------------------------------

    Thus, while this means we cannot rule out the potential for acute
concerns due to formaldehyde emissions from these facilities, we note
that the worst-case acute HQs are based on conservative assumptions
(e.g., worst-case meteorology coinciding with peak short-term 1-hour
emissions from each emission point, with a person located at the point
of maximum concentration during that hour). We also note that, as
stated earlier, the emissions estimates for formaldehyde are expected
to be an overestimate of emissions, further supporting our
determination that acute risks are not a significant concern for the
wool fiberglass source category.
    Comment: One commenter stated that AEGLs or ERPGs were developed
for accidental release emergency planning and are not appropriate for
assessing daily human exposure to toxic air pollutants because they do
not include adequate safety and uncertainty factors. The commenter
stated that they are not meant to evaluate the acute impacts from
routine emissions that occur over the life of a facility and cannot be
relied upon to protect the public from the adverse effects of exposure
to toxic air pollutants. The commenter concluded that their use is not
appropriate in risk assessments and urged the EPA to increase its
reliance on the California RELs to address acute exposures in the
residual risk assessments.
    Response: The EPA does not rely exclusively upon AEGL or ERPG
values for assessment of acute exposures. Rather, the EPA's approach is
to consider various acute health effect reference values (see the
preamble to the November 2011 proposal (76 FR 72781)), including the
California REL, in assessing the potential for risks from acute
exposures. To better characterize the potential health risks associated
with estimated acute exposures to HAP, and in response to a key
recommendation from the SAB's peer review of the EPA's RTR risk
assessment methodologies, we generally examine a wider range of
available acute health metrics (e.g., RELs, AEGLs) than we do for our
chronic risk assessments. This is in response to the SAB's
acknowledgement that there are generally more data gaps and
inconsistencies in acute reference values than there are in chronic
reference values. In some cases, when Reference Value Arrays for HAP
have been developed, we consider additional acute values (i.e.,
occupational and international values) to provide a more complete risk
characterization. As discussed in the preamble to the November 2011
proposal, the exposure guidelines the EPA considers depends on which
exposure guidelines are available for the various HAP emitted. The EPA
uses AEGL and ERPG values (when available) in conjunction with REL
values (when available) to characterize potential acute health risks.
However, it is often the case that HAP do not have all of these acute
reference benchmark values. In these instances, the EPA describes the
potential acute health risk in relation to the acute health values that
are available. Importantly, when interpreting the results, we are
careful to identify the benchmark being used and the health
implications associated with any specific benchmark being exceeded.
    Comment: According to one commenter, the EPA`s multipathway risk
assessment fell short because the EPA did not use ``allowable''
emissions for this assessment and the proposed rule shows multipathway
risks that are 60 times greater than the EPA's threshold. The commenter
stated that the EPA acknowledged in its 2014 risk assessment that the
emissions allowed by the standard may be up to 3 times greater than
actual emissions for phenol, methanol, and formaldehyde, such that the
HQ of 30 could be 3 times higher based on allowable emissions. The
commenter stated that by using actual emissions, the EPA's analysis is
likely to be an underestimate of the health risks from multipathway
routes of exposure. The commenter supports the EPA's use of
``allowable'' as well as ``actual'' emissions to assess inhalation
risk.
    Response: Consistent with previous risk assessments, the EPA
considers both allowable and actual emissions in assessing chronic
risks under CAA section 112(f)(2) (See, e.g., National Emission
Standards for Coke Oven Batteries (70 FR 19998-19999, April 15, 2005);
proposed and final National Emission Standards for Organic Hazardous
Air Pollutants from the Synthetic Organic Chemical Manufacturing
Industry (71 FR 34428, June 14, 2006, and 71 FR 76603, December 21,
2006). This approach is both reasonable and consistent with the
flexibility inherent in the Benzene NESHAP framework for assessing
acceptable risk and ample margin of safety, as developed in the Benzene
NESHAP (54 FR 38044, September 14, 1989). As a general matter, modeling
allowable emission levels is inherently reasonable since this reflects
the maximum level sources could emit and still comply with national
emission standards. But, it is also reasonable to consider actual
emissions, where such data are available, in the acceptable risk and
ample margin of safety analyses. See National Emission Standards for
Coke Oven Batteries (70 FR 19992, 19998, April 15, 2005). The commenter
claims that limiting our review to actual emissions would be
inconsistent with the applicability section of Part 63 rules. As
explained, however, we did not limit our review to actual emissions.
    The commenter also urged the agency to rely on allowable emissions
for the purpose of our acute assessment. The

use of allowable emissions was not considered due to the conservative
assumptions used to gauge worst-case potential acute health effects.
The conservative assumptions built into the acute health risk screening
analysis include: (1) Use of peak 1-hour emissions that are, on
average, 10 times the annual average 1-hour emission rates; (2) that
all emission points experience peak emissions concurrently; (3) worst-
case meteorology (from 1 year of local meteorology); and (4) that a
person is located downwind at the point of maximum impact during this
same 1-hour period. Thus, performing an acute screen based on allowable
emissions would be overly conservative and at best, of questionable
utility to decision makers.
    Comment: Two commenters stated that the EPA does not have authority
to consider ``total facility'' emissions in conducting the residual
risk assessments for a given source category. The commenter argued that
it would be impossible for the EPA to fulfill its unambiguous
obligation for CAA section 112(f) standards to protect public health
with an ample margin of safety in cases where facilities contain
sources in a category where the 8-year deadline for conducting the CAA
section 112(f) risk review precedes the adoption of MACT standards for
other sources at the facilities. One commenter added that CAA section
112(f)(2)(A) requires EPA to promulgate standards on a source category
basis. Another commenter continued that this provision unambiguously
requires the CAA section 112(f) risk assessment to be focused
exclusively on ``emissions from a source in the category or
subcategory,'' asserting that the EPA does not have authority to
consider emissions from any sources other than those in the source
category or subcategory under review at that time.
    Response: We disagree that examining facility-wide risk in a risk
assessment conducted under CAA section 112(f) exceeds the EPA's
authority. The development of facility-wide risk estimates provides
additional information about the potential cumulative risks in the
vicinity of the RTR sources, as one means of informing potential risk-
based decisions about the RTR source category in question. While we
recognize that, because these risk estimates were derived from
facility-wide emissions estimates which have not generally been
subjected to the same level of engineering review as the source
category emission estimates, they may be less certain than our risk
estimates for the source category in question, they remain important
for providing context as long as their uncertainty is taken into
consideration.
    Section 112(f)(2) of the CAA expressly preserves our use of the