[Federal Register Volume 78, Number 72 (Monday, April 15, 2013)]
[Proposed Rules]
[Pages 22369-22406]
[FR Doc No: 2013-07257]

Vol. 78

Monday,

No. 72

April 15, 2013

Part II

Environmental Protection Agency

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40 CFR Part 63

 National Emissions Standards for Hazardous Air Pollutants: Mineral
Wool Production and Wool Fiberglass Manufacturing; National Emission
Standards for Hazardous Air Pollutants for Gas-Fired Melting Furnaces
Located at Wool Fiberglass Manufacturing Area Sources; Proposed Rule

Federal Register / Vol. 78 , No. 72 / Monday, April 15, 2013 /
Proposed Rules

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 63

[EPA-HQ-OAR-2010-1041 and EPA-HQ-OAR-2010-1042; FRL-9682-8]
RIN 2060-AQ90

National Emissions Standards for Hazardous Air Pollutants:
Mineral Wool Production and Wool Fiberglass Manufacturing; National
Emission Standards for Hazardous Air Pollutants for Gas-Fired Melting
Furnaces Located at Wool Fiberglass Manufacturing Area Sources

AGENCY: Environmental Protection Agency.

ACTION: Proposed rule; notice of public hearing.

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SUMMARY: This action proposes chromium and particulate matter (for
metals) standards for wool fiberglass gas-fired glass-melting furnaces
at area sources and adds these sources to the category list in the
Urban Air Toxics Strategy. It also proposes amendments to the existing
major source rules for Mineral Wool and Wool Fiberglass, supplementing
the rule proposed on November 25, 2011. The proposed area source
standards for the gas-fired glass-melting furnaces used to make wool
fiberglass would increase the level of environmental protection.

DATES: Comments must be received on or before May 30, 2013. If anyone
contacts the EPA requesting a public hearing by April 22, 2013, we will
hold a public hearing on May 6, 2013. Under the Paperwork Reduction
Act, comments on the information collection provisions are best assured
of having full effect if the Office of Management and Budget receives a
copy of your comments on or before May 15, 2013.

ADDRESSES: Submit your comments on the proposed wool fiberglass area
source rule and the major source RTR amendments, identified by Docket
ID Number EPA-HQ-OAR-2010-1042, or the mineral wool RTR amendments,
identified by EPA-HQ-OAR-2010-1041, by one of the following methods:
     http://www.regulations.gov. Follow the instructions for
submitting comments.
     Email<EMAIL_ADDRESS>Attention Docket ID Number
EPA-HQ-OAR-2010-1041 or EPA-HQ-OAR-2010-1042.
     Fax:<PHONE_NUMBER>, Attention Docket ID Number EPA-HQ-
OAR-2010-1041 or EPA-HQ-OAR-2010-1042.
     Mail: U.S. Postal Service, send comments to: EPA Docket
Center, EPA West (Air Docket), Attention Docket ID Number EPA-HQ-OAR-
2010-1041 or EPA-HQ-OAR-2010-1042, U.S. Environmental Protection
Agency, Mailcode: 2822T, 1200 Pennsylvania Ave. NW., Washington, DC
20460. Please include a total of two copies. In addition, please mail a
copy of your comments on the information collection provisions to the
Office of Information and Regulatory Affairs, Office of Management and
Budget, Attn: Desk Officer for EPA, 725 17th Street NW., Washington, DC
20503.
     Hand Delivery/Courier: U.S. Environmental Protection
Agency, EPA West (Air Docket), Room 3334, 1301 Constitution Ave. NW.,
Washington, DC 20004, Attention Docket ID Number EPA-HQ-OAR-2010-1041
or EPA-HQ-OAR-2010-1042. Such deliveries are only accepted during the
Docket's normal hours of operation, and special arrangements should be
made for deliveries of boxed information.

Instructions: Direct your comments on the Mineral Wool RTR to Docket ID
Number EPA-HQ-OAR-2010-1041 and direct your comments on the Wool
Fiberglass RTR and proposed area source rule to Docket ID Number EPA-
HQ-OAR-2010-1042. The EPA's policy is that all comments received will
be included in the public docket without change to http://www.regulations.gov, including any personal information provided,
unless the comment includes information claimed to be CBI or other
information whose disclosure is restricted by statute. Do not submit
information that you consider to be CBI or otherwise protected through
www.regulations.gov or email. The www.regulations.gov Web site is an
``anonymous access'' system, which means the EPA will not know your
identity or contact information unless you provide it in the body of
your comment. If you send an email comment directly to the EPA without
going through www.regulations.gov, your email address will be
automatically captured and included as part of the comment that is
placed in the public docket and made available on the Internet. If you
submit an electronic comment, the EPA recommends that you include your
name and other contact information in the body of your comment and with
any disk or CD-ROM you submit. If the EPA cannot read your comment due
to technical difficulties and cannot contact you for clarification, the
EPA may not be able to consider your comment. Electronic files should
avoid the use of special characters, any form of encryption, and be
free of any defects or viruses. For additional information about the
EPA's public docket, visit the EPA Docket Center homepage at http://www.epa.gov/epahome/dockets.htm.
    Docket: The EPA has established dockets for these rulemakings under
Docket ID Number EPA-HQ-OAR-2010-1041 (Mineral Wool Production) and
EPA-HQ-OAR-2010-1042 (Wool Fiberglass Manufacturing). All documents in
the docket are listed in the www.regulations.gov index. Although listed
in the index, some information is not publicly available, e.g., CBI or
other information whose disclosure is restricted by statute. Certain
other material, such as copyrighted material, will be publicly
available only in hard copy. Publicly available docket materials are
available either electronically in www.regulations.gov or in hard copy
at the Air and Radiation Docket, EPA/DC, EPA West, Room B102, 1301
Constitution Ave. NW., Washington, DC. The Public Reading Room is open
from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding legal
holidays. The telephone number for the Public Reading Room is (202)
566-1744, and the telephone number for the Air Docket is (202) 566-
1742.

FOR FURTHER INFORMATION CONTACT: For questions about these proposed
actions, contact Ms. Susan Fairchild, Sector Policies and Programs
Division (D243-04), Office of Air Quality Planning and Standards, U.S.
Environmental Protection Agency, Research Triangle Park, North Carolina
27711; telephone<PHONE_NUMBER>; fax number:<PHONE_NUMBER>; and email
address<EMAIL_ADDRESS>For information about the
applicability of the NESHAP to a particular entity, contact Scott
Throwe, Office of Enforcement and Compliance Assurance, U.S. EPA
Headquarters Ariel Rios Building, 1200 Pennsylvania Avenue NW., Mail
Code: 2227A, Washington, DC 20460; telephone number:<PHONE_NUMBER>;
fax number:<PHONE_NUMBER>; email address<EMAIL_ADDRESS>
SUPPLEMENTARY INFORMATION:
    Acronyms and Abbreviations. The following acronyms and
abbreviations are used in this document.

AEGL acute exposure guideline levels
CAA Clean Air Act
CBI Confidential Business Information
CFR Code of Federal Regulations
CO Carbon monoxide
COS Carbonyl sulfide
EPA Environmental Protection Agency
ESP electrostatic precipitators
FA flame attenuation
GP General Provisions
HAP hazardous air pollutants

HCl Hydrogen chloride
HF Hydrogen fluoride
HI Hazard Index
HQ Hazard Quotient
lb/ton pounds per ton
MACT maximum achievable control technology
MIR maximum individual risk
NAICS North American Industry Classification System
NaOH Sodium hydroxide
NESHAP National Emissions Standards for Hazardous Air Pollutants
NTTAA National Technology Transfer and Advancement Act
OAQPS Office of Air Quality Planning and Standards
OMB Office of Management and Budget
PM Particulate matter
RFA Regulatory Flexibility Act
RS rotary spin
RTO regenerative thermal oxidizers
RTR residual risk and technology review
SBA Small Business Administration
SO2 Sulfur dioxide
SSM startup, shutdown, and malfunction
tpy tons per year
TTN Technology Transfer Network
UMRA Unfunded Mandates Reform Act

    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?
    C. What should I consider as I prepare my comments for the EPA?
    D. When will a public hearing occur?
II. Background Information for Proposed Area Source Standards
    A. What is the Wool Fiberglass Manufacturing source category?
    B. What are the HAP-emitting processes in wool fiberglass
manufacturing at area and major sources?
    C. What is the regulatory history for wool fiberglass
manufacturing?
    D. What is the authority for the development of NESHAP for area
sources?
    E. What sources did EPA look to in assessing GACT?
    F. Upon what set of data are the limits for glass-melting
furnaces located at area sources based?
III. What are the proposed requirements for glass-melting furnaces
located at area sources?
    A. What are the proposed applicability requirements?
    B. What are the proposed emission limits for gas-fired glass-
melting furnaces located at wool fiberglass manufacturing area
sources?
    C. What are the proposed measurement methods, monitoring,
reporting and recordkeeping requirements for glass-melting furnaces
located at wool fiberglass manufacturing area sources?
    D. What are the proposed decisions and actions related to
startup, shutdown and malfunction provisions?
IV. How did we develop the proposed standards for glass-melting
furnaces located at wool fiberglass manufacturing area sources?
    A. How did the EPA select the emissions sources and pollutants
to regulate?
    B. How did the EPA select the format for the proposed rule for
glass-melting furnaces located at wool fiberglass manufacturing area
sources?
    C. How did the EPA determine the proposed emission standards for
glass-melting furnaces located at wool fiberglass manufacturing area
sources?
    D. How did the EPA determine the compliance and monitoring
requirements for the Wool Fiberglass Manufacturing area sources
proposed rule?
    E. How did the EPA determine compliance dates for the proposed
Wool Fiberglass Manufacturing area sources rule?
    F. How did the EPA determine recordkeeping and reporting
requirements for the Wool Fiberglass Manufacturing area sources
proposed rule?
V. Impacts of the Proposed Wool Fiberglass Manufacturing Area Source
Rule
    A. What are the air impacts for the proposed Wool Fiberglass
Manufacturing area source rule?
    B. What are the cost impacts for the proposed Wool Fiberglass
Manufacturing area source rule?
    C. What are the non-air quality health, environmental and energy
impacts for the proposed Wool Fiberglass Manufacturing area source
rule?
    D. What are the economic impacts of the proposed Wool Fiberglass
Manufacturing area source rule?
VI. What are the proposed changes to Mineral Wool Production
(Subpart DDD) and Wool Fiberglass Manufacturing (Subpart NNN) major
source rules?
    A. Subpart DDD--Mineral Wool Production Major Source Rule
    B. Subpart NNN--Wool Fiberglass Manufacturing Major Source Rule
    C. Revisions to Startup, Shutdown and Malfunction Provisions
VII. Impacts of the Proposed Changes to Mineral Wool Production
(Subpart DDD) and Wool Fiberglass Manufacturing (Subpart NNN) Major
Source Rules
    A. Subpart DDD--Mineral Wool Production Major Source Rule
    B. Subpart NNN--Wool Fiberglass Manufacturing Major Source Rule
VIII. Statutory and Executive Order Reviews
    A. Executive Order 12866: Regulatory Planning and Review and
Executive Order 13563: Improving Regulation and Regulatory Review
    B. Paperwork Reduction Act
    C. Regulatory Flexibility Act
    D. Unfunded Mandates Reform Act
    E. Executive Order 13132: Federalism
    F. Executive Order 13175: Consultation and Coordination With
Indian Tribal Governments
    G. Executive Order 13045: Protection of Children From
Environmental Health Risks and Safety Risks
    H. Executive Order 13211: Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use
    I. National Technology Transfer and Advancement Act
    J. Executive Order 12898: Federal Actions To Address
Environmental Justice in Minority Populations and Low-Income
Populations

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 below.

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

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

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

    In addition to being available in the docket, an electronic copy of
this proposed action will also be available on the worldwide web
through the EPA's TTN. Following signature, a copy of the proposed
action will be posted on

the TTN's policy and guidance page for newly proposed and promulgated
rules at the following address:  http://www.epa.gov/ttn/caaa/new.html.
The TTN provides information and technology exchange in various areas
of air pollution control. Additional information is available on the
RTR Web page at  http://www.epa.gov/ttn/atw/rrisk/rtrpg.html. This
information includes source category descriptions and detailed
emissions and other data that were used as inputs to the proposed rule
development.

C. What should I consider as I prepare my comments for the EPA?

    Submitting CBI. Do not submit information containing CBI to the EPA
through http://www.regulations.gov or email. Clearly mark the part or
all of the information that you claim to be CBI. For CBI information on
a disk or CD ROM that you mail to the EPA, mark the outside of the disk
or CD ROM as CBI and then identify electronically within the disk or CD
ROM the specific information that is claimed as CBI. In addition to one
complete version of the comment that includes information claimed as
CBI, a copy of the comment that does not contain the information
claimed as CBI must be submitted for inclusion in the public docket. If
you submit a CD ROM or disk that does not contain CBI, mark the outside
of the disk or CD ROM clearly indicating that it does not contain CBI.
Information not marked as CBI will be included in the public docket and
the EPA's electronic public docket without prior notice. Information
marked as CBI will not be disclosed except in accordance with
procedures set forth in 40 CFR part 2. Send or deliver information
identified as CBI only to the following address: Roberto Morales, OAQPS
Document Control Officer (C404-02), Office of Air Quality Planning and
Standards, U.S. Environmental Protection Agency, Research Triangle
Park, North Carolina 27711, Attention Docket ID Number EPA-HQ-OAR-2010-
1042 (Wool Fiberglass).

D. When will a public hearing occur?

    If a public hearing is requested by April 22, 2013, it will be held
on May 6, 2013, at the EPA's Research Triangle Park Campus room C113,
109 T.W. Alexander Drive, Research Triangle Park, NC 27711. The hearing
will convene at 1 p.m. (Eastern Standard Time) and end at 5 p.m.
(Eastern Standard Time). Please contact Pamela Garrett at (919) (541-
7966) or at<EMAIL_ADDRESS>to request a hearing, to determine
if a hearing will be held and to register to speak at the hearing, if
one is held. If a hearing is requested, the last day to pre-register in
advance to speak at the hearing will be Wednesday, May 1, 2013.
Additionally, requests to speak will be taken the day of the hearing at
the hearing registration desk, although preferences on speaking times
may not be able to be fulfilled. If you require the service of a
translator or special accommodations such as audio description, please
let us know at the time of registration. If no one contacts the EPA
requesting a public hearing to be held concerning this proposed rule by
April 22, 2013 a public hearing will not take place.
    If a hearing is not requested by April 22, 2013 one will not be
held. If a hearing is held it will provide interested parties the
opportunity to present data, views or arguments concerning the proposed
action. The EPA will make every effort to accommodate all speakers who
arrive and register. Because this hearing, if held, will be at a U.S.
governmental facility, individuals planning to attend the hearing
should be prepared to show valid picture identification to the security
staff in order to gain access to the meeting room. In addition, you
will need to obtain a property pass for any personal belongings you
bring with you. Upon leaving the building, you will be required to
return this property pass to the security desk. No large signs will be
allowed in the building, cameras may only be used outside of the
building and demonstrations will not be allowed on federal property for
security reasons. The EPA may ask clarifying questions during the oral
presentations but will not respond to the presentations at that time.
Written statements and supporting information submitted during the
comment period will be considered with the same weight as oral comments
and supporting information presented at the public hearing. If a
hearing is held on May 6, 2013, written comments on the proposed rule
must be postmarked by June 5, 2013. Commenters should notify Ms.
Garrett if they will need specific equipment, or if there are other
special needs related to providing comments at the hearing. The EPA
will provide equipment for commenters to show overhead slides or make
computerized slide presentations if we receive special requests in
advance. Oral testimony will be limited to 5 minutes for each
commenter. The EPA encourages commenters to provide the EPA with a copy
of their oral testimony electronically (via email or CD) or in hard
copy form. Verbatim transcripts of the hearings and written statements
will be included in the docket for the rulemaking. The EPA will make
every effort to follow the schedule as closely as possible on the day
of the hearing; however, please plan for the hearing to run either
ahead of schedule or behind schedule. Information regarding the hearing
(including information as to whether or not one will be held) will be
available at: http://www.epa.gov/ttnatw01/woolfib/woolfipg.html. Again,
all requests for a public hearing to be held must be received by April
22, 2013.

II. Background Information for Proposed Area Source Standards

A. What is the Wool Fiberglass Manufacturing source category?

    In 1992, the EPA listed the Wool Fiberglass Manufacturing major
source category and defined that category to include any facility
engaged in producing wool fiberglass from sand, feldspar, sodium
sulfate, anhydrous borax, boric acid or any other materials. In the
wool fiberglass manufacturing process, molten glass is formed into
fibers that are bonded with an organic resin to create a wool-like
material that is used as thermal or acoustical insulation. The Wool
Fiberglass Manufacturing source category includes, but is not limited
to, the following processes: Glass-melting furnace, marble-forming,
refining, fiber-forming, binder application, curing and cooling. Though
the listing was for major sources, all of the manufacturing process
steps described here are applicable to both major and area sources. The
only difference is that area sources use a formulation for some or all
of their binders that does not contain HAP, and, thus, emissions do not
exceed the major source threshold. These changes to the bonded lines
are independent of and occur downstream of the furnace. Also, furnaces
located at major and area sources have the same emissions profiles.
    Wool fiberglass manufacturing facilities at major and area sources
typically operate one or more manufacturing lines. Refined raw
materials for the glass batch are weighed, mixed, and conveyed to the
glass-melting furnace, which may be gas-fired, electric, oxygen-
enriched or gas and electric combined.
    The glass-melting furnace is lined with refractory bricks,
providing thermal insulation and corrosion protection. According to
industry statements in product specification materials and in ICR
responses regarding refractory composition and furnace design, these
bricks may contain significant amounts (over 94 percent by weight) of
chromium-containing

compounds.\1\ Specifically, the 114 responses, which were completed by
all wool fiberglass companies, listed the chromium content of the
refractory linings of the glass melting furnaces. The chromium content
of the refractories in use at wool fiberglass furnaces ranged from 30-
94 percent chromium compounds, with a chromium content of up to 68
percent (chromium by weight). The primary component of wool fiberglass
is silica (quartz) sand, but it also includes varying quantities of
feldspar, sodium sulfate, anhydrous borax, boric acid, previously
melted glass and many other materials. Previously melted glass in the
form of marbles or crushed recycled glass (cullet) is a primary
component in most batches.
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    \1\ See product specifications from Saint-Gobain Corporation
(chromium refractory product line and SEFPRO) at saint-gobain.com
and in the docket to this rule.
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    In the first step of wool fiberglass manufacturing, raw materials
are introduced continuously or in batches on top of a bed of molten
glass into glass-melting furnaces where they mix and dissolve at
temperatures ranging from 2,700 [deg]F to 3,100 [deg]F (1,500 [deg]C to
1,700 [deg]C), and are transformed by a series of chemical and thermal
reactions to molten glass.
    In the second step of wool fiberglass manufacturing, fibers are
formed using either of two methods: The rotary spin (RS) method or the
flame attenuation (FA) method. In the RS process, centrifugal force
causes molten glass to flow through small holes in the wall of a
rapidly rotating cylinder. In the FA process, molten glass flows by
gravity from a small glass-melting furnace, or pot, to form threads
that are then attenuated (stretched to the point of breaking) with air
and/or flame.
    After the fibers are formed, they are sprayed with a binder to hold
the fibers together. Both major and area sources use binders. The
bonded fibers are then collected as a mat on a moving conveyor. Binder
compositions vary with product type. After application of the binder
and formation of the mat, the conveyor carries the newly formed mat
through an oven for curing of the thermosetting resin contained in the
binder and then through a cooling section. Some products do not require
curing and/or cooling and FA manufacturing lines do not have cooling
processes. Low and high-temperature thermal oxidizers are used to
control emissions of phenol, formaldehyde, and methanol from curing
operations on bonded lines at major sources.

B. What are the HAP-emitting processes in wool fiberglass manufacturing
at area and major sources?

    Glass-melting furnaces emit metal HAP (chromium, cadmium,
beryllium, manganese, nickel, lead and arsenic), which are present in
the particulate emissions. Particulate emissions are caused by
entrainment of dust from batch dumping and the combustion process and
from melting of the raw mineral materials. In addition, emissions of
chromium also result from entrainment of materials eroded from the
refractory lining of the glass-melting furnace and the glass-melting
furnace exhaust stack. Several HAP metals, including lead and arsenic,
are released from the batch materials and from the use of contaminated
cullet i.e., crushed recycled glass (64 FR 31695 (June 14, 1999)). As
shown in Table 2 below, the total metal emissions from all sources is
about 1,800 pounds per year (1,300 from major sources and 500 from area
sources), of which 620 pounds are chromium compounds. Area sources
contribute approximately 80 pounds of chromium compounds; major sources
contribute the balance of 540 pounds of chromium compounds.

                 Table 2--Total Metals and Chromium Emissions by Furnace Type and Source, lb/yr
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                                       Number of furnaces      Total metals emissions   Chromium emissions  (lb/
                                   --------------------------          (lb/yr)                     yr)
                                                             ---------------------------------------------------
                                       Major         Area        Major         Area        Major         Area
----------------------------------------------------------------------------------------------------------------
Electric Furnaces.................           21           46  ...........  ...........           10           10
Gas-Fired.........................            8            8  ...........  ...........          530           70
                                   -----------------------------------------------------------------------------
    Total.........................           29           54          760          420          540           80
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    Glass-melting furnaces may be either gas-fired, electric, oxygen-
enriched or a combination of gas and electric. About 80 percent of the
glass-melting furnaces used in the wool fiberglass industry are
electric (e.g., steel shell or cold-top) and about 20 percent are gas-
fired (e.g., air gas, recuperative air gas, or oxyfuel). Glass pull
rates for glass-melting furnaces typically range from 20 to 240 tons
per day, but can go up to 435 tons per day. Emissions from glass-
melting furnaces are typically controlled by baghouses or ESP. Electric
glass-melting furnaces typically have low PM and metal HAP emissions
without add-on controls as a result of their design. Operators of these
units maintain a thick crust of raw materials on top of the molten
glass, which impedes the release of heat and keeps the air temperature
of the glass-melting furnace below 300 [deg]F (120 [deg]C).
    Glass-melting furnaces also emit acid gases (hydrofluoric and
hydrochloric acid) that result from the presence of chlorides and
fluorides in the raw materials. Total emissions of acid gases from both
major and area sources are 24 tons per year (about 19 tons from major
sources and about 5 tons from area sources).
    The forming and binding step occurs at both area and major sources.
Emissions from the forming and binding step include formaldehyde,
phenol, and methanol. These emissions occur post-furnace, when the
volatile components of the binder come in contact with the hot fibers.
A portion of the binder components pass through the conveyor and into
the control device (thermal oxidizer, catalytic oxidizer or scrubber).
However, at area sources some or all of the binders used are formulated
to contain no HAP. Though air emissions of non-HAP containing binders
still occur, the overall emissions of HAP from binder application are
either eliminated or significantly reduced (if some HAP containing
binders are still used) to a level where the facility is not a major
source.
    As explained in our 1997 major source MACT rulemaking (62 FR 15229-
530), exposure to the HAPs emitted by wool fiberglass manufacturing can
cause reversible or irreversible health effects including carcinogenic,
respiratory, nervous system, developmental, reproductive, and/or dermal
health effects. However, chromium emissions from furnaces are

not affected by the reformulation of the binder. Chromium emissions are
of particular concern. The effects of inhaling chromium depend on
whether the oxidation state of the metal is trivalent or hexavalent.
Trivalent chromium is substantially less toxic than hexavalent
chromium. Both types of chromium irritate the respiratory tract.
Hexavalent chromium inhalation is associated with lung cancer, and EPA
has classified it as a Class A known human carcinogen, per EPA's
classification system for the characterization of the overall weight of
evidence for carcinogenicity.\2\
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    \2\ From ``Guidelines for Carcinogen Risk Assessment'', 51 FR
33991-34003, September 24, 1986. For more information on chromium's
inhalation carcinogenicity: http://www.epa.gov/iris/subst/0144.htm--
Section II: Carcinogenicity Assessment for Lifetime Exposure. For
more information on the support for the summary of the
carcinogenicity of chromium in EPA's Integrated Risk Information
System (IRIS): http://www.epa.gov/iris/toxreviews/0144tr.pdf. For
the most recent guideline document for Carcinogen Risk Assessment:
http://www.epa.gov/raf/publications/pdfs/CANCER_GUIDELINES_FINAL_3-25-05.PDF.
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    Here, we have a situation where the agency had listed and regulated
metal HAP emissions from wool fiberglass furnaces as part of Subpart
NNN, the major source MACT. As explained above, many of the area
sources at issue were, in fact, subject to Subpart NNN, and were
required to meet the PM limits (as a surrogate for metal HAP) in that
rule. These sources are no longer subject to Subpart NNN because they
no longer meet the definition of a ``wool fiberglass facility,'' since
they do not use a phenol-formaldehyde binder in their manufacturing
lines. Recent data provided by industry confirm that the gas-fired
glass-melting furnaces located at area sources emit urban metal HAP,
including significant amounts of chromium.

C. What is the regulatory history for wool fiberglass manufacturing?

    Section 112 of the Clean Air Act requires the agency to list and
promulgate NESHAP in order to control, reduce or otherwise limit the
emissions of HAP from categories of major and area sources. Pursuant to
the various specific listing requirements in section 112(c), the agency
listed 174 categories of major and area sources that would be subject
to NESHAP (57 FR 31576, July 16, 1992). The Wool Fiberglass
Manufacturing major source category was on that list.
    In the 1992 listing notice, we provided source category
descriptions and noted that the list, consistent with the statute, may
be revised from time to time as additional information became
available. The agency also noted the requirement to list area sources
pursuant to the Urban Air Toxics Strategy under section 112(c) and (k).
(See 57 FR 31582).
    We proposed the NESHAP for the Wool Fiberglass Manufacturing major
source category on March 31, 1997 (61 FR15228). At proposal, we
explained that we were aware of only three facilities that were area
sources. We further explained that two glass-melting furnaces located
at these area sources had MACT floor level controls. 40 CFR Part 63,
Subpart NNN (62 FR 31695). The EPA promulgated the final NESHAP for the
Wool Fiberglass Manufacturing major source category on June 14, 1999
(62 FR 31695), and those requirements are codified at 40 CFR Part 63,
Subpart NNN.
    The requirements of the major source NESHAP apply to HAP emitted
from the following new and existing sources at a wool fiberglass
manufacturing facility:
    1. Glass-melting furnaces located at a wool fiberglass
manufacturing facility;
    2. Rotary spin wool fiberglass manufacturing lines producing a
bonded wool fiberglass building insulation product; and
    3. Flame attenuation wool fiberglass manufacturing lines producing
a bonded pipe product and bonded heavy density product. (40 CFR
63.1380).
    With regard to the two manufacturing lines, rotary spin and flame
attenuation, the major source NESHAP provides that a bonded product is
wool fiberglass to which a phenol-formaldehyde binder has been applied.
(40 CFR 63.1381).
    As explained previously, HAP emitted from glass-melting furnaces
include acid gases and metals, such as chromium, cadmium, beryllium,
manganese, nickel, lead and arsenic. Formaldehyde, phenol and methanol
are the HAP emitted from forming, cooling and curing processes, which
are the processes associated with the rotary spin and flame attenuation
lines.
    The major source NESHAP set standards for PM (as a surrogate for
non-Hg metal HAP) to address emissions from glass-melting furnaces and
formaldehyde (as a surrogate for phenol and methanol) to address
emissions from the forming, cooling, and curing processes. (40 CFR
63.1382). Thus, the NESHAP regulates emissions from both glass-melting
furnaces and the manufacturing lines. The record supporting the major
source NESHAP (Subpart NNN) provides that regulation of PM, chromium
and metal HAP emissions from the glass-melting furnaces would occur
irrespective of whether the lines were producing a bonded product. The
EPA did not intend to exempt any major sources or incentivize such
sources to avoid MACT coverage by producing non-bonded products (i.e.,
wool fiberglass to which a phenol-formaldehyde binder was not applied).
Rather the EPA contemplated that the Wool Fiberglass Manufacturing
NESHAP would regulate emissions from both glass-melting furnaces and
rotary spin and flame attenuation lines, the latter of which are part
of the forming, curing and cooling process.\3\
---------------------------------------------------------------------------

    \3\ For example, in the response to comments document supporting
the final major source NESHAP, EPA clarified the applicability of
the rule. Specifically, EPA rejected a request to limit the rule to
the manufacturing lines, noting that the commenter's suggested
revision ``would alter the applicability of the rule'' such that
glass-melting furnaces would not be covered. Further, in response to
the commenter's suggested change of the definition of ``wool
fiberglass,'' EPA responded that ``while the suggested change may
help to clarify the EPA's intent to cover only manufacturing lines
producing bonded wool fiberglass products, it would create confusion
over the rule's coverage of glass-melting furnaces.'' EPA stated:
``Because the EPA's intent is to regulate all glass-melting furnaces
located at wool fiberglass plants that are major sources of HAP, and
not just those melters that feed molten glass to manufacturing lines
producing bonded wool fiberglass products, the EPA has decided to
not modify the definition of `wool fiberglass' by adding `bonded to
the definition. The EPA believes that other definitions and the
applicability section of the rule are clear on the EPA's intent to
regulate manufacturing lines that produce bonded products and not
non-bonded products.'' (Emphasis added). See Comments 2.2 and 2.3 of
the response to comment documents for the Wool Fiberglass
Manufacturing Source Category, which can be found in the docket for
this rulemaking.
---------------------------------------------------------------------------

    The major source NESHAP, however, also defined the term ``wool
fiberglass manufacturing facility'' as ``any facility manufacturing
wool fiberglass on a rotary spin manufacturing line or on a flame
attenuation manufacturing line.'' (40 CFR 63.1381). As noted above, in
order to have a rotary spin manufacturing line or a flame attenuation
manufacturing line you must produce a bonded product, which is a
product to which a phenol-formaldehyde binder has been applied. Thus, a
facility that does not use phenol-formaldehyde binders does not
manufacture a bonded product, and therefore does not have a rotary spin
manufacturing line or a flame attenuation manufacturing line as defined
in the NESHAP. If the facility does not have a rotary spin
manufacturing line or a flame attenuation manufacturing line it does
not meet the definition of wool fiberglass manufacturing facility and
therefore, would no longer be subject to the Wool Fiberglass
Manufacturing NESHAP. Thus, the wool fiberglass manufacturing facility
definition appears to be in tension with the

applicability provision, (in 40 CFR 63.1380, which is described above),
to the extent the provision states that the requirements of the NESHAP
apply to HAP emitted from the glass-melting furnaces located at a wool
fiberglass manufacturing facility (40 CFR 63.1380).
    As shown in a 2002 applicability determination for Johns Mansville
(JM), the narrow definition of a wool fiberglass manufacturing facility
resulted in a determination that a rotary spin line that stopped making
bonded products was no longer subject to Subpart NNN.\4\
---------------------------------------------------------------------------

    \4\ The determination provided, in pertinent part, ``Based on
the definitions provided in section 63.1381, EPA agrees that if the
[rotary spin line located at the] JM Penbryn Plant is no longer
using a phenol-formaldehyde binder, the facility no longer meets the
definition of a wool fiberglass manufacturing facility in Subpart
NNN.'' Memorandum from Michael S. Alushin, Director for Compliance
Assessment and Media Programs Division, Office of Compliance, USEPA
to Karl Mangels, Air Compliance Branch, USEPA, Region II, (August 1,
2002)). EPA also agreed ``that as a result of the switch to a non
phenol-formaldehyde binder, the glass-melting furnace is not subject
to Subpart NNN since it is no longer located at a wool fiberglass
manufacturing facility.'' (Memorandum from Michael S. Alushin,
Director for Compliance Assessment and Media Programs Division,
Office of Compliance, USEPA to Karl Mangels, Air Compliance Branch,
USEPA, Region II, (August 1, 2002)).
---------------------------------------------------------------------------

    However, the phase out of phenol-formaldehyde binders does not
reduce or otherwise change emissions from the glass-melting furnace.
This is because the first step of wool fiberglass manufacturing at both
major and area sources (i.e., where raw materials are introduced)
occurs in the glass-melting furnace and as earlier explained total
chromium compounds, arsenic, cadmium, beryllium, lead, manganese and
nickel are some of the HAP emitted from glass-melting furnaces. These
emissions are different from HAP emissions from the forming and bonding
section of rotary spin and flame attenuation manufacturing lines; which
as explained above are formaldehyde, phenol and methanol or none of
these where a facility has phased out the use of phenol-formaldehyde
binders. Thus, sources that no longer meet the definition of a wool
fiberglass facility because they no longer use phenol-formaldehyde
binders on the rotary spin and flame attenuation lines are no longer
subject to Subpart NNN. However, they still emit metal HAP from the
glass-melting furnaces. These HAP include total chromium compounds,
lead, arsenic, cadmium, beryllium, manganese and nickel, which are HAP
that the EPA has identified under sections 112(c)(3) and (k)(3) as part
of the 30 urban HAP (the ``urban HAP'').
    On November 25, 2011, the EPA proposed revisions to the Mineral
Wool and the Wool Fiberglass Manufacturing NESHAP, 40 CFR part 63,
subparts DDD and NNN, respectively, to address the results of the
technology review and residual risk review that the EPA is required to
conduct under sections 112(d)(6) and 112(f)(2) (76 FR 72770). The
limits in those proposed amendments apply to major sources, that is,
sources emitting at least 10 tons per year of a single HAP or 25 tons
per year of any combination of HAP.
    In the November 25, 2011 proposal, the agency noted that since
promulgation of the 1999 NESHAP, sources had modified certain processes
by using non-HAP binders instead of phenol-formaldehyde binders (76 FR
72770). As noted above, a facility that no longer uses phenol-
formaldehyde binders does not meet the definition of ``wool fiberglass
facility'' under Subpart NNN. Many sources that were subject to the
major source NESHAP (Subpart NNN) have eliminated the use of phenol-
formaldehyde binders and these sources now emit less than 10 tons per
year of a single HAP or 25 tons per year of any combination of HAP. We
understand that 20 of the existing 30 wool fiberglass facilities have
become area sources through the phase-out of phenol-formaldehyde in the
binders. However, the glass-melting furnaces at these sources continue
to emit chromium and other HAP metal compounds. As explained above,
emissions from glass-melting furnaces are completely separate and
independent from emissions from the bonding portion of the process.
Further, while replacement of phenol-formaldehyde binders with non-HAP
binders is an environmentally responsible, or ''green'' choice within
the wool fiberglass manufacturing industry, recent data from industry
show that gas-fired glass-melting furnaces specifically continue to
emit chromium and other HAP metal compounds, and for furnaces located
at area sources these emissions are not currently regulated pursuant to
CAA section 112.
    While subpart NNN applies to wool fiberglass manufacturing
facilities that are major sources, today's proposed rule would apply to
gas-fired glass-melting furnaces located at wool fiberglass
manufacturing facilities that are area sources (subpart NN). As
explained below in section IV, we are listing gas-fired glass-melting
furnaces located at wool fiberglass manufacturing facilities that are
area sources pursuant to section 112(c)(3) and (k)(3)(B) of the CAA.

D. What is the authority for the development of NESHAP for area
sources?

1. Authority Under Section 112(k) Area Source Program
    Sections 112(c)(3) and (k) of the CAA require the EPA to identify
and list the area source categories that represent 90 percent of the
emissions of the 30 urban air toxics associated with area sources and
subject them to standards under the CAA (section 112(d)). Cross
referencing section 112(c)(3), section 112(k)(3) requires the EPA to
identify a list of at least 30 air toxics that pose the greatest
potential health threat in urban areas (the ``urban'' HAP). Taken
together, these requirements are known as the Urban Air Toxics Strategy
(Strategy). These are the HAP that present the greatest threat to
public health in the largest number of urban areas (section
112(k)(3)(B)(i) of the Act). The EPA is also required to ``assure that
sources accounting for 90 percent or more of the 30 identified
hazardous air pollutants are subject to standards.'' (Section
112(k)(3)(B)(ii) and section 112(c)(3)). Under the Strategy, the EPA
has developed standards to control toxic air pollutants from area
sources. For the Strategy, the EPA identified a list of 33 air toxics
in the area source program under which a total of 68 area source
categories were identified which represented 90 percent of the
emissions of the 33 listed air toxics. Under the Strategy, EPA
regulated these 68 source categories of urban HAP in 56 subparts of the
Code of Federal Regulations.5 6
---------------------------------------------------------------------------

    \5\ For EPA's notice on the Urban Air Toxics Strategy, see 64 FR
38706, 38715-716 (July 19, 1999.)
    \6\ EPA issued final area source standards in the following FR
notices:
---------------------------------------------------------------------------

    As noted above, section 112(k)(3)(B)(ii) requires the EPA to
``assure that [area] sources accounting for 90 percent or more of the
30 identified hazardous air pollutants [the 30 urban HAP] are subject
to standards.'' (Emphasis added). Nothing in the CAA prevents the
agency from going beyond the statutory minimum of 90 percent. Indeed,
to date, we have established emission standards for sources accounting
for almost 100 percent of area source emissions of certain urban HAP.
For example, we have established emission standards for various source
categories emitting dioxin, which is an urban HAP, and these categories
represent 100 percent of area source dioxin emissions.
    To date, the agency has regulated 90 percent of sources accounting
for area source chromium, manganese, lead and nickel emissions, all of
which are urban

HAP emitted by gas-fired glass-melting furnaces, and 93 percent of
sources accounting for cadmium emissions and 99 percent for arsenic and
beryllium emissions.\7\ Consistent with the authority provided in
section 112(c)(3) and (k)(3)(B), the agency is listing and proposing
emission standards for these urban metal HAP emissions from gas-fired
glass-melting furnaces located at area sources. With this regulation,
pursuant to section 112(c)(3) and (k)(3)(B), the agency will have
subjected additional sources to regulation for urban metal HAP, which
is wholly consistent with the goals of the Strategy. Under the
Strategy, we went above the 90 percent when it was feasible to do
so.\8\ For example, EPA subjected 99 percent of sources of arsenic and
beryllium compounds to regulation under the Strategy. We have no
requirement to limit our regulation to the minimum of 90 percent of
sources; we however must subject at least 90 percent of the sources of
the urban HAP to regulation under the strategy.
---------------------------------------------------------------------------

    \7\ See. ``Technical Memorandum. Emission Standards for Meeting
the 90 Percent Requirement under Section 112(c)(3) and Section
112(k)(3)(B) of the Clean Air Act'' From Nathan E. Topham,
Environmental Engineer, USEPA February 18, 2011.
    \8\ For the listing notices of the Strategy, see 64 FR 38705,
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.
---------------------------------------------------------------------------

    As we are adding gas-fired glass-melting furnaces located at area
sources to the source category list, we are also proposing standards
for the category.\9\ See section III.B below regarding the proposed
standards.
---------------------------------------------------------------------------

    \9\ We have made several revisions to the 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.
---------------------------------------------------------------------------

2. Alternative Standards for Area Sources Under Section 112(d)(5)
    Under CAA section 112(d)(5), EPA may elect to promulgate standards
or requirements for area sources ``which provide for the use of
generally available control technologies or management practices by
such sources to reduce emissions of hazardous air pollutants.''
Additional information on generally available control technologies or
management practices (GACT) is found in the Senate report on the
legislation (Senate report Number 101-228, December 20, 1989), which
describes GACT as:

* * * methods, practices and techniques which are commercially
available and appropriate for application by the sources in the
category considering economic impacts and the technical capabilities
of the firms to operate and maintain the emissions control systems.

Consistent with the legislative history, we can consider costs and
economic impacts in determining GACT. Determining what constitutes GACT
involves considering the control technologies and management practices
that are generally available to the area sources in the source
category.
    In setting GACT, we always look to the standards applicable to
major sources in the same industrial sector to determine if the control
technologies and management practices are transferable and generally
available to area sources. In appropriate circumstances, we may also
consider technologies and practices at area and major sources in
similar categories to determine whether such technologies and practices
could be considered generally available for the area source category at
issue. In this case, the control technologies and managment practices
for major sources are transferable because major source glass-melting
furnaces are no different than area source glass-melting furnaces.
Finally, as we have already noted, in determining GACT for a particular
area source category, we consider the costs and economic impacts of
available control technologies and management practices on that
category.
    GACT differs from MACT in that cost can be considered in the first
instance when establishing a GACT standard. By contrast, when
establishing MACT standards pursuant to section 112(d)(3), EPA must
determine the average emission limitation achieved by the best
performing 12 percent of existing sources and the emission limitation
achieved by the best controlled similar source for new sources, without
regard to cost.
    As explained in greater detail in section III.B below, we
determined that GACT standards for area sources should be the same as
the major source standards proposed for PM and chromium on November 25,
2011, pursuant to section 112(d)(6), based on the similarity between
production processes, emission points, emissions, and control
technologies that are characteristic of both major and area source wool
fiberglass manufacturing facilities and considerations of cost.\10\
---------------------------------------------------------------------------

    \10\ The EPA also considers the costs and economic impacts of
available control technologies and management practices when
determining whether to revise a standard pursuant to section
112(d)(6).
---------------------------------------------------------------------------

E. What sources did EPA look to in assessing GACT?

    As noted above, determining what constitutes GACT involves
considering the control technologies and management practices that are
generally available to the area sources in the source category. We also
consider the standards applicable to major sources in the same
industrial sector, which is particularly relevant here as the control
technologies and management practices are transferable and generally
available to area sources. Given the above, it is appropriate to
consider both major and area sources in assessing GACT.
    In order to identify all wool fiberglass manufacturing facilities
we relied on the original listing of facilities from the 1999 NESHAP,
based on industry comments. Major sources are subject to Title V, and
are identified in a database used for Title V permitting purposes. The
agency used this Title V database to identify major sources in the Wool
Fiberglass Manufacturing source category. There are currently 30
facilities in this source category, of which 10 are major sources and
20 are area sources. Currently, area sources operate 54 glass-melting
furnaces while major sources operate 29 glass-melting furnaces. We also
note that the industry has provided information that some of the major
sources have already filed permit modifications with the appropriate
permitting agencies to become area sources, but the permitting agency
has not yet acted on the request.

F. Upon what set of data are the limits for glass-melting furnaces
located at area sources based?

    At the time of the November 25, 2011, RTR proposal, the EPA had
information that all glass-melting furnaces emit metal HAP in the form
of particulate emissions. In addition, subsequent to the November 25,
2011, proposal, the EPA requested information through a section 114
information request regarding PM and chromium compounds that are either
used in or emitted by glass-melting furnaces at facilities that engage
in wool fiberglass manufacturing. The EPA has evaluated the responses
and confirmed that over 90 percent (15 out of 16) of gas-fired glass-
melting furnaces emit chromium compounds at measurable amounts. These
data have been compiled with previously submitted industry source tests
into a database for this source category and serve as the technical
basis for this area source rulemaking.
    The EPA reviewed the entire set of data for the wool fiberglass
manufacturing industry, which includes

both major and area sources. We conducted QA/QC analyses to ensure data
accuracy, identified the area sources and arrayed those data according
to the magnitude of the emissions and control device.
    We considered whether to include all glass-melting furnaces in the
set of data or only those glass-melting furnaces located at area
sources. We concluded it was most reasonable to base the emission limit
on the entire set of data, and not on a subset of area sources for the
reasons described below.
    First, due to the definition of ``wool fiberglass facility'' in
Subpart NNN, the set of area sources is constantly growing. When
facilities change their status from a major source to an area source,
they typically do so as a result of changes in their binder
formulation, a process occurring downstream of the glass-melting
furnace. In 2002, two out of 33 facilities were area sources; within 10
years that number had increased 10-fold, and by December 2012, 20 out
of 30 had become area sources. The bonded lines are independent of
glass-melting furnaces; the binder formulation change does not affect
glass-melting furnace operations, limits or production.
    Second, the glass-melting furnaces in use when the facility is a
major source are the same glass-melting furnaces operating in the same
manner as when it becomes an area source. Because there is no
difference between the glass-melting furnace operations at area sources
and those at major sources, we found no reason to differentiate the
glass-melting furnaces located at major sources from the furnaces
located at area sources.
    Third, there is no definitive cut-off date to determine when
facilities that are major sources become area sources. As discussed
earlier, the industry is phasing out its use of phenol-formaldehyde
based binders, but each company/facility has its own schedule for the
transition to non phenol-formaldehyde binders. As explained earlier,
because the HAP emissions resulting from the use of phenol-formaldehyde
binders place the facility in major source status (that is, the HAP
emissions are at least 10 tpy of a single HAP or 25 tpy of a
combination of HAP), when a facility discontinues the phenol-
formaldehyde binder and begins use of a non-HAP binder, it becomes an
area source, emitting less than major source levels.
    The limits we are proposing in today's action are GACT limits, and
are based on the ``generally available control technologies or
management practices by such sources to reduce emissions of HAP.'' We
note that this is the same data set on which technology review was
based for the wool fiberglass RTR proposed rule.\11\ We therefore
propose that the larger industry dataset, including glass-melting
furnaces at both major and area wool fiberglass manufacturing sources,
is the appropriate set on which to base the proposed GACT limits.
---------------------------------------------------------------------------

    \11\ This is similar to our decision in the Portland Cement
NESHAP (74 FR 21155, May 6, 2009), where we based the PM, mercury,
and total hydrocarbon limits on all the kilns used by industry for
which we had data because there were no differences between kilns
located at major sources and those located at area sources.
---------------------------------------------------------------------------

III. What are the proposed requirements for glass-melting furnaces
located at area sources?

    As previously discussed, we have determined the EPA's intent in
developing the 1999 Wool Fiberglass Manufacturing NESHAP was to
regulate metal HAP emissions from all glass-melting furnaces, but now
many glass-melting furnaces are no longer regulated by the NESHAP.
Based on industry-provided data, these glass-melting furnaces emit
metal HAP. However, we have determined that gas-fired glass-melting
furnaces at wool fiberglass manufacturing facilities can emit higher
levels of metal HAP, and also higher than expected levels of chromium
than electric glass-melting furnaces. This is due to the use of high
chromium refractories above the glass melt line, and use of these
refractories is essential to obtain the desired glass-melting furnace
life. Also, the industry has indicated that the current trend is to
replace air gas glass-melting furnaces with oxyfuel glass-melting
furnaces.12 13 Oxyfuel glass-melting furnaces have the
highest potential for elevated chromium emissions as discussed further
in section IV.A of this preamble. Accordingly, we believe it is
appropriate to add gas-fired glass-melting furnaces at wool fiberglass
manufacturing facilities that are located at area sources to the list
of area sources regulated in the Urban Air Toxics Program.
---------------------------------------------------------------------------

    \12\ US DOE Energy Efficiency and Renewable Energy, Industrial
Technologies Program, Final Technical Report. ``Compressive Creep
and Thermophysical Performance of Refractory Materials''. Oak Ridge
National Laboratories. June 2006.
    \13\ Oxygen-Enhanced Combustion, Baukal, Charles E., Jr. 1998.
---------------------------------------------------------------------------

    The following sections present the applicability requirements,
emission limits, measurement methods, monitoring, notification,
recordkeeping and reporting requirements we are proposing for these
area sources. The rationale for these requirements follows this
section.

A. What are the proposed applicability requirements?

    The proposed rule would apply to gas-fired glass-melting furnaces
located at wool fiberglass manufacturing facilities that are at area
sources. Gas-fired furnaces include, but are not limited to, oxyfuel,
air gas and recuperative air gas glass-melting furnaces.
    We also considered having the limits apply only to glass-melting
furnaces constructed using chromium in the refractory of the glass-
melting furnace. However, we also learned from the section 114
responses that most wool fiberglass glass-melting furnaces are
constructed of refractory materials containing similar chromium
content. The potential for chromium emissions is related more to the
amount of high chromium refractories above the glass melt line and the
air temperature above the glass melt. The furnace energy source (gas
versus electric) is a more reliable indicator of the potential for
chromium emissions from the refractory than refractory chromium
content. Therefore, we opted to use the energy source as a basis of
determining the types of area source furnaces to regulate rather than
the chromium content of the refractory. We therefore propose that all
wool fiberglass gas-fired glass-melting furnaces located at area
sources should be subject to the same emission limit being proposed
today, regardless of the chromium content of the refractory bricks used
to construct them.

B. What are the proposed emission limits for gas-fired glass-melting
furnaces located at wool fiberglass manufacturing area sources?

    We are proposing a GACT standard of 0.00006 pounds (lb) of chromium
compounds per ton of glass pulled (0.06 lb per thousand tons glass).
This is the same limit we previously proposed for glass-melting
furnaces used by wool fiberglass manufacturing facilities at major
sources, pursuant to section 112(d)(6) (76 FR 72770).
    We found that emissions of glass-melting furnaces, including those
located at area sources, are generally below this limit. Thus, most
glass-melting furnaces, specifically gas-fired glass-melting furnaces
at wool fiberglass manufacturing facilities, show this limit can be met
using generally available control technologies and practices.
    We are also proposing a PM emission limit of 0.33 lb per ton of
glass pulled. This is the same limit we are proposing for major sources
in this action based on technology review showing most glass-melting
furnaces using baghouses or

electrostatic precipitators for PM control. Similarly, PM emissions
from gas-fired glass-melting furnaces located at wool fiberglass
manufacturing facilities are all below this limit. The above proposed
limits apply at all times. See Sierra Club v. EPA, 551 F.3d 1019 (D.C.
Cir. 2008) (Vacating the provisions of 40 CFR 63.6(f)(1) and 63.6(h)(1)
that exempt sources from the requirement to comply with otherwise
applicable CAA section 112(d) emissions standards during periods of
startup, shutdown and malfunctions).
    Finally, because the analyses for technology review and for GACT
both consider costs and analyze available technologies, and because
major and area sources share the same control approaches, it is a
reasonable outcome that the emission limits proposed for major sources
under the technology review and the proposed GACT limits are the same.

C. What are the proposed measurement methods, monitoring, reporting and
recordkeeping requirements for glass-melting furnaces located at wool
fiberglass manufacturing area sources?

    To be consistent with the major source rule, we are proposing the
same test methods and procedures for PM and chromium compounds
contained in 40 CFR part 63, subpart NNN.
    In order to minimize the burden associated with stack testing, we
are proposing a reduction in performance testing frequency. We are
proposing that sources measuring chromium compounds in two successive
performance tests that are less than 75 percent of the limit of the
rule be allowed to reduce their testing frequency (for chromium) to no
less than every 3 years. We are also proposing that sources measuring
PM emissions less than 75 percent of the limit in two successive
performance tests be allowed to reduce their PM testing frequency to no
less than every 3 years. With each of these performance test frequency
reductions, the reduced frequency benefit is lost if a subsequent re-
test shows PM or chromium emissions above 75 percent of the emission
standard. In that case, two successive performance tests demonstrating
compliance below 75 percent of the emission limit would be required for
a source to, once again, qualify for less frequent emissions testing.
    To be consistent with the wool fiberglass manufacturing major
source rule, we are proposing that glass-melting furnaces located at
area sources must meet all applicable monitoring requirements and all
notification, recordkeeping and reporting requirements contained in 40
CFR part 63, subpart NNN.

D. What are the proposed decisions and actions related to startup,
shutdown and malfunction provisions?

    Consistent with Sierra Club v. EPA, the EPA is proposing standards
in this rule that apply at all times. In proposing these standards, the
EPA has taken into account startup and shutdown periods. Based on the
information before the Agency, which includes information provided by
industry, we expect facilities can meet the proposed emission standards
during startup and shutdown. Nothing in the record suggests that
emissions will be greater during startup and shutdown periods and the
record confirms that the control devices are operated during these
periods.
    We are also including an alternative compliance provision that
would allow sources to demonstrate compliance with the standards during
startup and shutdown by keeping records showing that your furnace
emissions were controlled using air pollution control devices operated
at the parameters established by the most recent performance test that
showed compliance with the standard. During startup and shutdown of a
gas-fired furnace the operating temperatures and amounts of raw
materials available to produce air emissions are lower than other
operating periods. This would tend to result in lower uncontrolled
emissions levels. Therefore, it is reasonable to assume that by
continuing to operate the air pollution control equipment during these
periods a source will be in compliance with the emissions limit.
    For the reasons discussed in the preamble to the November 2011
proposal and as discussed further below, we are proposing in this area
source rule to include an affirmative defense to civil penalties for
violations of emission limits that are caused by malfunctions. See 40
CFR 63.881 of the proposed rule (defining ``affirmative defense'' to
mean, in the context of an enforcement proceeding, a response or
defense put forward by a defendant, regarding which the defendant has
the burden of proof, and the merits of which are independently and
objectively evaluated in a judicial or administrative proceeding).
    We also are proposing other regulatory provisions to specify the
elements that are necessary to establish this affirmative defense; the
source must prove by a preponderance of the evidence that it has met
all of the elements set forth in 40 CFR 63.886. (See 40 CFR 22.24). The
criteria are designed in part to ensure that the affirmative defense is
available only where the event that causes a violation of the emission
limit meets the narrow definition of malfunction in 40 CFR 63.2
(sudden, infrequent, not reasonable preventable and not caused by poor
maintenance and or careless operation). For example, to successfully
assert the affirmative defense, the source must prove by a
preponderance of the evidence that the violation ``[w]as caused by a
sudden, infrequent, and unavoidable failure of air pollution control
and monitoring equipment, process equipment, or a process to operate in
a normal or usual manner * * *.'' The criteria also are designed to
ensure that steps are taken to correct the malfunction, to minimize
emissions in accordance with 40 CFR 63.882(b) when finalized and to
prevent future malfunctions. For example, the source must prove by a
preponderance of the evidence that ``[r]epairs were made as
expeditiously as possible when a violation occurred * * *'' and that
``[a]ll possible steps were taken to minimize the impact of the excess
emissions on ambient air quality, the environment and human health * *
*.'' In any judicial or administrative proceeding, the Administrator
may challenge the assertion of the affirmative defense and, if the
respondent has not met its burden of proving all of the requirements in
the affirmative defense, appropriate penalties may be assessed in
accordance with section 113 of the CAA (see also 40 CFR 22.27).
    The EPA included an affirmative defense in this proposed rule in an
attempt to balance a tension, inherent in many types of air
regulations, to ensure adequate compliance while simultaneously
recognizing that despite the most diligent of efforts, emission
standards may be violated under circumstances beyond the control of the
source. The EPA must establish emission standards that ``limit the
quantity, rate, or concentration of emissions of air pollutants on a
continuous basis.'' 42 U.S.C. 7602(k)(defining ``emission limitation
and emission standard''). See generally Sierra Club v. EPA, 551 F.3d
1019, 1021 (D.C. Cir. 2008) Thus, the EPA is required to ensure that
section 112 emissions standards are continuous. The affirmative defense
for malfunction events meets this requirement by ensuring that even
where there is a malfunction, the emission standard is still
enforceable through injunctive relief. The United States Court of

Appeals for the Fifth Circuit recently upheld the EPA's view that an
affirmative defense provision is consistent with section 113(e) of the
Clean Air Act. Luminant Generation Co. LLC v. United States EPA, 699
F.3d.427 (5th Cir. Oct. 12 2012) (upholding the EPA's approval of
affirmative defense provisions in a CAA State Implementation Plan).
While ``continuous'' standards, on the one hand, are required, there is
also case law indicating that in many situations it is appropriate for
the EPA to account for the practical realities of technology. For
example, in Essex Chemical v. Ruckelshaus, 486 F.2d 427, 433 (D.C. Cir.
1973), the D.C. Circuit acknowledged that in setting standards under
CAA section 111 ``variant provisions'' such as provisions allowing for
upsets during startup, shutdown and equipment malfunction ``appear
necessary to preserve the reasonableness of the standards as a whole
and that the record does not support the `never to be exceeded'
standard currently in force.'' See also, Portland Cement Association v.
Ruckelshaus, 486 F.2d 375 (D.C. Cir. 1973). Though intervening case law
such as Sierra Club v. EPA and the CAA 1977 amendments call into
question the relevance of these cases today, they support the EPA's
view that a system that incorporates some level of flexibility is
reasonable. The affirmative defense simply provides for a defense to
civil penalties for violations that are proven to be beyond the control
of the source. By incorporating an affirmative defense, the EPA has
formalized its approach to upset events. In a Clean Water Act setting,
the Ninth Circuit required this type of formalized approach when
regulating ``upsets beyond the control of the permit holder.'' Marathon
Oil Co. v. EPA, 564 F.2d 1253, 1272-73 (9th Cir. 1977). See also, Mont.
Sulphur & Chem. Co. v. United States EPA, 2012 U.S. App. LEXIS 1056
(Jan 19, 2012)(rejecting industry argument that reliance on the
affirmative defense was not adequate). But see, Weyerhaeuser Co. v.
Costle, 590 F.2d 1011, 1057-58 (D.C. Cir. 1978) (holding that an
informal approach is adequate). The affirmative defense provisions give
the EPA the flexibility to both ensure that its emission standards are
``continuous'' as required by 42 U.S.C. 7602(k), and account for
unplanned upsets and thus support the reasonableness of the standard as
a whole.

IV. How did we develop the proposed standards for glass-melting
furnaces located at wool fiberglass manufacturing area sources?

    At proposal of the technology review and residual risk review of
the major source NESHAP in 2011, we proposed emission limits for
chromium compounds because hexavalent chromium is emitted from wool
fiberglass glass-melting furnaces and stated that we planned to
regulate wool fiberglass glass-melting furnaces located at area sources
in a future action. (76 FR 72770). The highest emitting glass-melting
furnace, an oxyfuel glass-melting furnace, was measured emitting at 550
pounds per year, while other glass-melting furnaces were emitting
between five and 250 pounds of chromium per year. We considered whether
it was possible for other facilities to emit chromium compounds at the
level of the highest emitting facility and proposed that, under the
same circumstances, other wool fiberglass manufacturing facilities
could emit at similar levels. We reasoned at proposal in 2011 that
nothing prevents a wool fiberglass company from constructing a glass-
melting furnace identical to the glass-melting furnace with the highest
chromium emissions.
    As explained in the November 25, 2011, proposal, the industry trade
association (National Association of Insulation Manufacturers of
America (NAIMA) had conducted a voluntary survey of companies that
manufacture wool fiberglass. The survey sought test data on HAP
emissions, process equipment, control devices and other aspects of the
wool fiberglass manufacturing operations. With regard to total chromium
compounds, the survey requested information on the chromium content of
glass-melting furnaces at different parts of the glass-melting furnace
and required all glass-melting furnaces to be tested for both total
chromium and hexavalent chromium emissions. This voluntary survey was
followed by the EPA's section 114 information request letter requesting
test data on total chromium compounds emissions from all glass-melting
furnaces and information on glass-melting furnace design and refractory
chromium content.

A. How did the EPA select the emissions sources and pollutants to
regulate?

    As previously discussed, wool fiberglass manufacturing facilities
emit the following urban air toxics: arsenic, beryllium, cadmium,
chromium, lead, manganese, and nickel (PM is regulated as a surrogate
for these metals) from the glass-melting furnace; and phenol,
formaldehyde and methanol from the binding process. The emissions
profile of glass-melting furnaces at area sources and major sources are
identical. However, this is not true for emissions of formaldehyde from
the binding operation. A facility becomes an area source by minimizing
or eliminating binder formaldehyde emissions. For this reason, we
determined that it is not necessary to include the binding operation in
this proposed listing, and have limited the listing to chromium and PM
as a surrogate for the remaining metal HAP from glass-melting furnaces.
    The glass-melting furnace design (layout and location of chromium
refractory), energy source, and refractory age are the major factors
affecting chromium emissions from glass-melting furnaces.
    There are two types of glass-melting furnaces in the wool
fiberglass industry, gas-fired and electric. Oxyfuel, air gas, and
recuperative air gas are gas-fired; cold-top electric and electric
steel shell are electric glass-melting furnaces. All of these furnace
types emit metal HAP in the form of controlled PM emissions at similar
levels. However, based on new information gathered since the November
25, 2011, proposal of the major source RTR, we have determined that
gas-fired glass-melting furnaces at wool fiberglass manufacturing
facilities exhibit a greater potential to emit chromium compounds and
other metal HAP than electric furnaces, and also to convert trivalent
chromium to hexavalent chromium.
    Table 3 of this preamble presents a summary of the chromium test
data for wool fiberglass glass-melting furnaces. The data show a
significant range of chromium emissions. All of the glass-melting
furnace types have some sources that emit at very low levels, but only
gas-fired glass-melting furnaces show a potential to have chromium
emissions levels above the 0.00006 lb/ton glass pulled emissions level
proposed for glass-melting furnaces.

 Table 3--Range of Chromium Compound Emissions by Glass-Melting Furnace
                                  Type
------------------------------------------------------------------------
                                                           Cr compound
                                                         emissions (lb/
              Glass-melting furnace type                 1000 tons glass
                                                             pulled)
------------------------------------------------------------------------
Electric Steel Shell..................................     0.0022-00.039
Cold-Top Electric.....................................     0.00078-0.027
Air Gas...............................................        .0025-0.96
Oxy Fuel..............................................          .011-3.5
------------------------------------------------------------------------

    Available data indicate that all furnace types use high chromium

refractory in some areas. However, information provided by the industry
on furnace design indicates that gas-fired glass-melting furnaces have
a higher potential to emit chromium compounds due to the placement of
the high chromium refractory, the physical layout of the furnace, the
size and placement of the burners in relation to the sides and top of
the glass-melting furnace, the depth from the burners to the top of the
raw materials, the temperature at and above the melt, and the oxide
concentration of the glass-melting furnace gas environment. In
addition, gas-fired furnaces show the greatest potential to convert
chromium to its most toxic form, hexavalent chromium, due to the
significantly higher temperature above the glass melt line of a gas-
fired furnace.
    These data (i.e., data submitted by the wool fiberglass
manufacturing industry on glass-melting furnace type and construction
materials in response to both NAIMA's voluntary survey and the agency's
section 114 letter) indicate that the highest emitting glass-melting
furnace is a gas-fired furnace, specifically, an oxyfuel glass-melting
furnace constructed using chromium refractories. However, all glass-
melting furnaces with the high chromium emissions were either oxyfuel
or air gas glass-melting furnaces. The section 114 information letter
required measurements of both hexavalent and total chromium as well as
identification of the location and chromium content of the refractories
used in glass-melting furnace construction.
    The reason for the higher emission potential for gas-fired glass-
melting furnaces is due to differences in design, construction
materials, and operation of gas-fired glass-melting furnaces compared
to electric glass-melting furnaces. A chromium refractory product has
the greatest resistance to heat and wear of any refractory in use
today. The temperatures above the melt in gas-fired glass-melting
furnaces range from 2,500 [deg]F to 4,500 [deg]F, while the
temperatures in electric glass-melting furnaces are a few hundred
degrees. Due to their higher operating temperatures, gas-fired glass-
melting furnaces are constructed using chromium refractories at various
parts of the glass-melting furnace that are above the molten glass,
including the crown. The chromium in the refractory is the source of
the chromium emissions from the gas-fired glass-melting furnaces.\14\
However, other influencing factors determine both the rate and
magnitude of the chromium emissions when chromium is available in the
furnace lining. The presence of chromium above the glass melt line, the
percentage of chromium available in the refractory, the rate of
degradation of the furnace interior, the chemistry of the wool
fiberglass `recipe', the temperature of the furnace, the oxidizing
atmosphere of the furnace, the placement and proximity of burners to
the furnace wall, and other design and construction factors contribute
to the corrosion and erosion of the gas-fired glass-melting furnace
refractory and the formation of hexavalent chromium furnace. In
addition, the high temperatures result in more of the chromium being
converted to its hexavalent state compared to electric furnaces.
---------------------------------------------------------------------------

    \14\ EPA Notes of meeting with Certainteed, April 14, 2011;
Industry Meetings with EPA on March 19, 2012; April 30, 2012; and
December 6, 2012; email from Lauren P. Alterman, Saint-Gobain
Corporation, regarding chrome emissions and refractory bricks,
August 6, 2012).
---------------------------------------------------------------------------

    Since our November 25, 2011, proposal, we have learned that if a
source of reasonably priced oxygen is available, the oxyfuel glass-
melting furnace is the design favored for use by glass manufacturers
due to the glass-melting furnace's low NOX emissions
(NOX is an ozone precursor), and low energy demands per
volume output of glass. The low NOX emissions of an oxyfuel
glass-melting furnace result from the fact that no air (which contains
nitrogen) is introduced into the high temperature zone above the glass
melt. Instead, the oxyfuel glass-melting furnace design mixes the
natural gas fuel with pure oxygen for combustion, thus reducing
NOX emissions.
    The DOE's office of Industrial Technology, in association with
industry experts from the glass manufacturing, refractory production
sectors and the Oak Ridge National Laboratory, conducted studies to
determine ways to optimize energy uses, needs and efficiencies in
industrial sectors. In these studies, industry experts agreed (Oak
Ridge National Laboratory, June 2006, p. 9) that oxyfuel glass-melting
furnaces will ultimately replace air gas glass-melting furnaces by 2020
due to these economic and environmental factors. For example, industry
experts participating in the Industrial Technologies Program (ITP),
under the Department of Energy's Energy Efficiency and Renewable Energy
program, described the demands an oxyfuel glass-melting furnace places
upon the refractory lining: ``The ITP has recognized that a reduction
in overall domestic energy consumption will occur if the primary
energy-consuming industries improve their own energy efficiencies.
Recognizing this need, the glass industry is currently converting
older, conventional air-fuel-fired furnaces to oxyfuel firing, or in
the case of new construction, is building new oxyfuel-fired furnaces
instead. This has caused oxyfuel technology to become one of the
fastest growing technologies in the glass industry because it promises
pollution abatement, increased glass-pull effectiveness, capital cost
savings and increased energy efficiency. For example, a recent study
has shown that approximately $202M in energy savings per year in 2005
and a $445M per year savings by 2020 could be expected with the
conversion of air/fuel to oxy-fuel-fired glass manufacturing furnaces.
These results, which reflect energy savings of 2.8 and 14.2 TBtu/year,
respectively, are based on the projection that 61 percent and 100
percent furnace conversions will occur by the years 2005 and 2020,
respectively.''
    Other studies (Metallurgical and Materials Transactions, Lee,Y.,
Nassaralla, C.L., 1998) advise us that, under normal industrial
temperatures, which can exceed 1,300 [deg] F., and oxidizing
conditions, trivalent chromium, which is present in the refractory,
oxidizes to hexavalent chromium.\15\ It was found that uncombined and
available oxides were responsible for a higher yield of hexavalent
chromium. Consequently, an increasing concentration of oxides in the
oxyfuel glass-melting furnace environment increases the formation of
chromium from the trivalent state to hexavalent state. The condition of
high oxides in the oxyfuel glass-melting furnace environment is one
characteristic of the highest emitting glass-melting furnace (see
Docket number EPA-HQ-OAR-2010-1042 document number 0067: Region 7 Notes
on CertainTeed Kansas City. June 10, 2011. 13 pages).
---------------------------------------------------------------------------

    \15\ Metallurgical and Materials Transactions B. ``Minimization
of Hexavalent Chromium in Magnesite-Chrome Refractory''. Y. Lee and
C. L. Nassaralla. Vol. 28 B, Oct. 1997--pp. 855-859.
---------------------------------------------------------------------------

    Moreover, while the degradation of the glass-melting furnace
refractory indicates increasing chromium emissions, that process does
not necessarily follow a normal and predictable pattern. The
degradation of refractories within the glass-melting furnace is a
function of numerous factors, including temperature, time, stress and
the composite effects of aging and creep response. These processes are
highly nonlinear, so the traditional equations that assume steady-state
deformation rates are not appropriate (DOE and Oak Ridge National
Laboratory, June 2006 p. 63).

    Although all glass-melting furnaces are constructed using chromium
refractories (NAIMA letter dated January 28, 2013. Industry Meeting
Notes, August 31, 2011) at and below the line of contact defined by the
refractory wall and the molten glass within the glass-melting furnace
(the glass/metal line), oxyfuel and some air gas glass-melting furnaces
have other glass-melting furnace parts constructed using chromium
refractories, such as the crown and forehearth. The use of chromium
refractories above the melt line is necessary to obtain the desired
furnace life and reduce the necessity for hot repairs of the furnace.
When the hot, corrosive and reactive gases of a gas-fired glass-melting
furnace come in contact with the high chromium refractories lining the
area above the glass melt in high temperature glass-melting furnaces,
the chromium is available to be oxidized and converted into its
hexavalent form.
    The cost of rebuilding a wool fiberglass glass-melting furnace
ranges from 10-12 million dollars; most of this cost is the cost of
skilled labor (C. Davis, CertainTeed Corp., April 2011). While chromium
refractories are more expensive than conventional refractories, they
are only incrementally so (DOE and Oak Ridge National Laboratory, June
2006, p. 1). When conventional (high alumina/silica) refractories are
used, the useful life of the glass-melting furnace is about 7 years.
Chromium refractories almost double the useful life of the glass-
melting furnace. Therefore, industry has a strong economic incentive to
develop and use longer lasting refractories in construction of the
glass-melting furnaces. Industry spokespersons have indicated that they
rely on using chromium refractories offering longer glass-melting
furnace life, and have commented that the EPA should regulate the
chromium emissions from wool fiberglass glass-melting furnaces rather
than regulate chromium content of refractories. (Email from
<EMAIL_ADDRESS>to persons at the EPA, July 27,
2012, 10:32 a.m., regarding chrome emissions and refractory bricks.)
    We have also found that as the refractories of the gas-fired glass-
melting furnaces degrade, the chromium of those refractories at and
above the metal/glass line is emitted as particulate to the outside
air. Chromium from the refractories below the metal/glass line is
absorbed into the molten glass and becomes vitrified with the other raw
minerals. Industry commented that refractory loss from degradation of
the refractory walls in use is approximately 20,000 pounds of
refractory annually (minutes of the August 31, 2011 Meeting with
Representatives of the Wool Fiberglass Industry and NAIMA). However,
much of the loss occurs below the glass melt line. The chromium
released below the glass melt line is believed to stay in the glass.
    The facility with the highest emitting glass-melting furnace (an
oxyfuel glass-melting furnace) submitted chromium testing for state
inventory reporting purposes over a seven-year period. As shown in
Table 4 below, those test results are extrapolated using permitted
production rates to calculate approximate annual emissions of chromium
compounds. The calculations show that in 2004, chromium emissions are
estimated to be less than 5 pounds annually. Repeated chromium
emissions testing for the State reports in 2005 and 2008 and permitted
production rates for those years show chromium emissions increased to
540 pounds per year for the same glass-melting furnace. Emissions
testing conducted in 2010 speciating chromium by its compounds show
that 93 percent of the chromium was in the hexavalent state.

          Table 4--Summary of Chromium Emissions From 2004-2010
------------------------------------------------------------------------
                                                 Glass-melting furnace
                                                 chromium emissions at
                     Year                         permitted production
                                                 rate, pounds per year
------------------------------------------------------------------------
2004.........................................                        <5
2005.........................................                        30
2008.........................................                       114
2010.........................................                       540
------------------------------------------------------------------------

    This glass-melting furnace was not reconstructed during this 7-year
period covered by the chromium testing. This indicates that a
degradation of the chromium refractory resulted in a significant
increase in chromium emissions during this period. We collected source
testing for all types of furnaces used in the wool fiberglass
manufacturing industry. Specifically, each air-gas and oxyfuel furnace
was tested, and facilities that operated identical electric furnaces
provided testing for one furnace along with design, construction, and
refractory information for all furnaces operated. Industry provided
schematics of all types of furnace designs showing that while all wool
fiberglass furnace `tanks' (holding the molten materials) are
constructed of high chromium refractory, only the gas-fired furnaces
may also be constructed from chromium refractories above the molten
glass. In our review of all the data submitted, only gas-fired furnaces
are designed in a manner that, during operation, may emit significant
amounts of chromium compounds. We, therefore, believe that because the
gas-fired furnaces are the only furnaces in which the chromium
refractory is exposed to oxidizing conditions at temperatures exceeding
1,300 [deg]F, gas-fired furnaces clearly demonstrate a greater
potential for increased chromium emissions. While the highest emitting
glass-melting furnace is located at a major source, we note, as we
discussed in the proposed RTR rule, that there is no difference in a
glass-melting furnace at a major source and the same design glass-
melting furnace at an area source facility.
    The thermal, physical and chemical properties of molten wool
fiberglass cause corrosion and erosion to the refractory lining of the
glass-melting furnace, and the glass-melting furnace must be
constructed of materials capable of resisting this environment. Because
oxygen burns very hot, some of the highest refractory performance
requirements in the industry are placed upon wool fiberglass oxyfuel
glass-melting furnaces (``New High Chrome Fused Cast Refractory for Use
in Contact With Highly Corrosive Glasses'', T.A. Myles and F. Knee, in
Ceramic Engineering and Science Proceedings, The American Ceramic
Society, 1986). Consequently, an oxyfuel glass-melting furnace used to
produce wool fiberglass must be constructed of chromium refractories
because these are the only types of materials currently available that
are suitable for this use and meet the rigorous practical demands of
wool fiberglass manufacturing. The industry has commented that the use
of chromium refractories is economically essential to wool fiberglass
manufacturing, because of normal high thermal and chemical stressors to
oxyfuel glass-melting furnaces, chromium refractories are preferred by
industry for economical and safe oxyfuel glass-melting furnace
operation. Construction using these materials significantly increases
the life of the glass-melting furnace (see Region 7 Notes on
CertainTeed Kansas City. June 10, 2011. p. 5 of 13; email from
<EMAIL_ADDRESS>to persons at the EPA, July 27,
2012, 10:32 a.m., regarding chrome emissions and refractory bricks).
    In summary, because of the advantages of oxyfuel glass-melting
furnaces over other wool fiberglass glass-melting furnace technology
described in the preceding discussions, we expect oxyfuel glass-melting
furnaces constructed of chromium refractories to replace many existing

wool fiberglass glass-melting furnaces of other designs (Letter from
NAIMA to Ms. Susan Fairchild, EPA, January 28, 2013), particularly as
sources of industrial oxygen are sited near wool fiberglass facilities
(Oxygen-Enhanced Combustion, Baukal, Charles E. Jr., Prince B. Eleazar
III, and Bryan C. Hoke, Jr. 1998).
    Emissions of the other metal HAP are very low for electric glass-
melting furnaces. This low emission potential is inherent in the glass-
melting furnace design. Electric glass-melting furnaces establish a
crust on the raw material at the surface of the molten glass. They use
electrodes which are embedded below the crust and within the molten
glass to maintain the temperature of the melt, while the temperature
above the melt is low. They also have lower air flows and low
turbulence above the glass melt. Therefore the potential for metal
emissions (in the form of PM entrained in the exhaust gas) from
electric glass-melting furnaces is much lower than from gas-fired
glass-melting furnaces.
    Electric furnaces also do not have the same potential to emit
chromium as gas-fired furnaces. Although electric glass-melting
furnaces are lined at and below the glass/metal line with chromium
refractories, they are constructed using either non-chromium
refractories (cold-top electric) or steel in place of refractories
(electric steel shell) above the glass/metal line. This design is used
because electric glass-melting furnaces operate with a dry batch cover
and are tapped at the bottom or end of the glass-melting furnace to
draw off the molten glass. Raw materials are constantly added to the
top of the glass-melting furnace in damp form and create a crust on top
of the molten glass. Steel shell glass-melting furnaces have a steel
enclosure above glass/metal the line and cold-top electric glass-
melting furnaces use non-chromium refractories above the glass/metal
line. The air above the melt inside an electric glass-melting furnace
is below 300 [deg]F, and is not hot enough to warrant use of chromium
refractories. Even if chromium refractories were used to construct the
crown of the electric glass-melting furnace, the temperature of an
electric glass-melting furnace above the glass/metal line is
insufficient to drive the chromium to its hexavalent state.
    Consequently, electric glass-melting furnaces do not have the same
potential to emit chromium compounds that gas-fired glass-melting
furnaces have, and accordingly, many of the chromium test data
collected at electric glass-melting furnaces are below the detection
level of the emissions measurement method. All the electric glass-
melting furnace test data were also below the proposed chromium limit
for glass-melting furnaces at major sources in the November 25, 2011,
proposed RTR rule amendments.
    Gas-fired furnaces also have a higher potential to emit PM, and
consequently metal HAP. This is because gas-fired furnaces require that
combustion air or oxygen and natural gas be blown into the furnace.
This increases the gas flow velocities and turbulence above the glass
melt tine, which increases the potential for particle entrainment in
the exhaust gas.
    EPA's original intent was to regulate metal emissions from glass-
melting furnaces, which at that time included all existing furnaces. We
have now determined that glass-melting furnaces at area source and
major source facilities have the same emissions profiles. Therefore, it
is appropriate to add glass-melting furnaces at wool fiberglass
manufacturing facilities to the area source list, and as previously
noted we have the statutory authority to do so. However, gas-fired
furnaces have a greater emissions potential than electric furnaces.
Metal HAP emissions from electric glass-melting furnaces are inherently
low, and more importantly, the potential to emit elevated amounts of
chromium are low. Therefore we are limiting this listing to the
furnaces with the greatest emissions potential, which are the gas-fired
furnaces. In addition, due to certain source category specific facts,
we are proposing limits for both PM and a separate limit for chromium.
(See Memo to File ``Development of Background Information on Proposed
Area Source Emissions Limits'', March 15, 2013.)
    Wool fiberglass glass-melting furnaces that are hybrid gas-fired
and electric glass-melting furnaces would be included in this action;
wool fiberglass glass-melting furnaces that are all-electric would not
be included. Therefore, in today's action we are proposing PM and
chromium compounds emission limits that would apply to gas-fired glass-
melting furnaces located at wool fiberglass manufacturing facilities
that are area sources. Electric glass-melting furnaces located at area
sources would not be subject to this proposed rule.
    In today's proposal, we are soliciting comment on whether to
regulate only gas-fired glass-melting furnaces located at area sources
or to regulate all glass-melting furnaces located at wool fiberglass
manufacturing facilities that are area sources. In addition we are
soliciting comment on the pollutants regulated.

B. How did the EPA select the format for the proposed rule for glass-
melting furnaces located at wool fiberglass manufacturing area sources?

    The emission points covered by this proposed area source rule were
selected to ensure control of chromium compounds and other metal HAP
emissions from gas-fired glass-melting furnaces located at area
sources. We are proposing to establish numerical emission limits in the
form of mass of pollutant (chromium compounds and PM) per mass of glass
pulled through the glass-melting furnace. The same format is used for
emission limits in both the area and the major source rules.
    The emission limits in the proposed rule provide flexibility for
the regulated community by allowing a regulated source to choose any
control technology or technique to meet the emission limits, rather
than requiring each unit to use a prescribed control method that may
not be appropriate in every case. The EPA solicits comment on the
format of the proposed standards.

C. How did the EPA determine the proposed emission standards for glass-
melting furnaces located at wool fiberglass manufacturing area sources?

    Under CAA section 112(d)(5), the Administrator may, in lieu of
standards requiring maximum achievable control technology (MACT) under
section 112(d)(2), elect to promulgate standards or requirements for
area sources ``which provide for the use of generally available control
technologies [``GACT''] or management practices by such sources to
reduce emissions of hazardous air pollutants.'' Further, legislative
history describes GACT as standards reflecting application of generally
available control technology, that is, ``methods, practices and
techniques which are commercially available and appropriate for
application by the sources in the category considering economic impacts
and the technical capabilities of the firms to operate and maintain the
emissions control systems'' (S. Rep. 101-228 (December 20, 1989). In
addition to technical capabilities of the facilities and availabilities
of control measures, legislative history suggests that we may consider
costs and economic impacts in determining GACT.
    In this proposed rule, we are setting emission standards to address
emissions of chromium compounds and other metal HAP from wool
fiberglass gas-fired glass-melting furnaces (i.e. cadmium, beryllium,
manganese, lead, and arsenic). In determining what

constitutes GACT for this proposed rule, we considered the control
technologies and management practices that are generally available to
gas-fired wool fiberglass furnaces at area sources by examining
relevant data and information, including information collected from all
known wool fiberglass manufacturing sources. We also considered the
risk and technology review standards proposed for major sources (76 FR
72770, November 25, 2011), to determine if the control technologies and
management practices proposed for the major sources are generally
available to area sources as well. Finally, we considered the costs of
available control technologies and management practices on area
sources.
    In setting GACT we look to the control technologies generally
available for major and area sources. From the information that we have
collected to date in conjunction with this rulemaking, which includes
stack testing and site visits at both major and area sources, we know
that area sources have the same types of emissions, emission sources,
and controls as major sources. Gas-fired wool fiberglass glass-melting
furnaces at major and area sources are using the same control
technologies (baghouses or electrostatic precipitators). The available
emission data show no discernible differences between area source and
major source furnaces. In fact, when a major source facility becomes an
area source, the furnace emission and emissions controls do not change.
Therefore, the control technologies used by major sources are generally
available for area sources.
    The data in the record show that major and area source furnaces are
equipped with technologies that effectively control chromium and metal
HAP emissions, including, but not limited to, ESPs and fabric filters.
In determining GACT, we examined different levels of control using
these generally available control technologies and evaluated the cost
of such control. We are proposing a PM emissions limit of 0.33 lb/ton
glass pulled, and a chromium emissions limit of 6.5 x 10-5
lb/ton glass pulled. We are proposing these limits because they reflect
a level of control that can be achieved cost-effectively using
generally available control technologies and management practices. See
Development of Background Information on Proposed Area Source Emissions
Limit, March 15, 2013.
    We estimate no costs or emission reductions associated with the
proposed PM standard because the record shows that all the gas-fired
area source furnaces are currently meeting the proposed emissions
limit. Significantly, however, the proposed PM limit will codify
current actual current PM emissions levels to prevent any future
increase in PM emissions. Without the proposed limits, these furnaces
could increase PM emissions at any time as they are no longer subject
to Subpart NNN.
    There are three area source gas-fired furnaces that currently do
not meet the proposed GACT for chromium. However, data are available
for industries with similar control requirements that demonstrate that
there are effective chromium control technologies available. We
searched other industries for controls that would remove chromium and
found that a sodium hydroxide (NaOH) scrubber is used in both high
temperature metallurgical industries and in the chromium electroplating
industry for removal of hexavalent chromium.\16\ Based on the
effectiveness of this technology on to two different types of exhaust
gas streams, we believe this control technology is transferable to wool
fiberglass furnaces. Though there are currently no NaOH scrubbers
applied in the wool fiberglass industry, there is currently one gas-
fired furnace equipped with a PM control followed by a wet scrubber for
SO2 control. This is directly analogous to using a NaOH wet
scrubber downstream of the PM controls to achieve additional chromium
removal. Assuming that the facilities not currently meeting the
proposed chromium emission limit opted to use the NaOH scrubbers to
achieve compliance, the cost of the proposed chromium emissions limit
is $7,600 per pound of chromium. This is a reasonable cost given that
chromium is an urban air toxic and that a significant portion of the
chromium emitted from gas-fired glass-melting furnaces is hexavalent
chromium, which is extremely toxic and carcinogenic even in low
amounts. We note that we found $11,000 per pound chromium removed to be
a reasonable cost in the final Chromium Electroplating RTR rulemaking,
where we regulated chromium compounds (77 FR 59220, September 19,
2012). For information on the methodology and more detailed results of
this analysis, see the memorandum, Costs and Emission Reductions for
the Proposed Wool Fiberglass Manufacturing NESHAP--Area Sources, in the
docket and section V.B of this preamble. We did, however, examine lower
limits and the costs associated therewith. See Development of
Background Information on Proposed Area Source Emissions Limit, March
15, 2013.
---------------------------------------------------------------------------

    \16\ NaOH Scrubber Information. Telephone discussion and emails
between vendors, companies and EPA. Steffan Johnson, Measurement
Policy Group. USEPA/OAQPS/SPPD.
---------------------------------------------------------------------------

    The proposed limits for area sources are identical to the limits we
have proposed for furnaces located at major sources as part of our
technology review under 112(d)(6). It is reasonable that the limits for
major and area sources be the same, especially, where, as here, there
are no discernible differences between area and major source furnaces.
Accordingly, we are proposing GACT standards for PM and chromium. We
solicit comment on the proposed GACT standards for PM and chromium.

D. How did the EPA determine the compliance and monitoring requirements
for the Wool Fiberglass Manufacturing area sources proposed rule?

    We are proposing testing, monitoring, notification, recordkeeping,
and reporting requirements to assure continuous compliance with the
requirements of the proposed rule and that are consistent with the
major source rule requirements in subpart NNN. In fact, the specific
requirements in the proposed rule reference the requirements in Sec.
63.1386 of subpart NNN. We solicit comment on the proposed compliance
and monitoring requirements for area sources. These proposed
requirements impose on facilities the minimum burden that is necessary
to ensure compliance with the proposed rule.

E. How did the EPA determine compliance dates for the proposed Wool
Fiberglass Manufacturing area sources rule?

    Section 112 of the CAA provides limits for the dates by which
affected sources must comply with the emission standards. New or
reconstructed units would be required to be in compliance with the
final rule immediately upon startup, or the date the final rule is
published in the Federal Register, whichever is later. The proposed
rule allows existing area sources up to one year to comply with the
final rule. The CAA provides that existing sources must comply as
expeditiously as possible but not later than 3 years after promulgation
of the final NESHAP. We do not believe that 3 years for compliance is
necessary to allow adequate time to design, install, and test control
systems. All facilities currently already meet the proposed PM limit.
If an area source must apply additional control to meet the chromium
limit, we believe one year is adequate time given

the fact that there is only one pollutant involved, and the available
chromium control technology can be added downstream of the current PM
controls and is a well established technology. However, sources can
always petition their permitting authorities to allow for additional
time to install controls pursuant to section 112(i)(3)(B). We solicit
comment on the proposed compliance dates for area sources.

F. How did the EPA determine recordkeeping and reporting requirements
for the Wool Fiberglass Manufacturing area sources proposed rule?

    Section 112 of the CAA requires the EPA to develop regulations that
include requirements for reporting the results of testing and
monitoring performed to determine compliance with the standards. In
today's action, we are proposing sources be required to comply with the
applicable requirements in the NESHAP General Provisions, subpart A of
40 CFR part 63, as referenced in Table 1 of the proposed rule. We
evaluated the General Provisions requirements, and included those we
determined to be the minimum notification, recordkeeping, and reporting
necessary to ensure compliance with, and effective enforcement of, the
proposed rule. The reports that we are proposing to be required are
found in 40 CFR 63.886 of the proposed rule.
    We also determined the necessary records that need to be kept to
demonstrate continuous compliance with the proposed emission limits.
These recordkeeping requirements are specified directly in the today's
proposed rule, and in the General Provisions to 40 CFR part 63. The
recordkeeping requirements are found in 40 CFR 63.886 of the proposed
rule. We are proposing that records be kept for 5 years in a form
suitable and readily available for EPA review. We are proposing that
records be kept on site for 2 years. Records may be kept off site for
the remaining 3 years.
    The General Provisions include specific requirements for
notifications, recordkeeping, and reporting. The reports are specified
in proposed 40 CFR 63.886.
    The notification of compliance status report required by 40 CFR
63.9(h) must include certifications of compliance with rule
requirements. The excess emissions and continuous system performance
report and summary report required by 40 CFR 63.10(e)(3) of the NESHAP
General Provisions (referred to in the rule as a compliance report)
would be required to be submitted semiannually for reporting periods
during which there was an exceedance of any emission limit, or a
monitored parameter, or when a deviation from any of the requirements
in the rule occurred, or if any process changes occurred, and
compliance certifications were reevaluated.

V. Impacts of the Proposed Wool Fiberglass Manufacturing Area Source
Rule

    The impacts presented in this section include the air quality,
cost, non-air quality and economic impacts of complying with the
proposed rule for wool fiberglass manufacturing located at facilities
that are area sources to comply with the proposed rule.

A. What are the air impacts for the proposed Wool Fiberglass
Manufacturing area source rule?

    We have estimated the potential emission reductions from
implementation of the proposed emission standards to be 50 pounds of
chromium compounds per year.
    We estimated emission reductions of the proposed rule for each gas-
fired glass-melting furnace. For all emission points, we first
calculated emissions at the current level of control for each facility
(referred to as the baseline level of control), and at the proposed
level of control. We calculated emission reductions as the difference
between the proposed level and baseline.

B. What are the cost impacts for the proposed Wool Fiberglass
Manufacturing area source rule?

    We considered the costs and benefits of achieving the proposed
emission limits and identified five facilities with a total of eight
glass-melting furnaces that would be subject to the proposed
requirements. All eight glass-melting furnaces would have to conduct
annual testing to demonstrate compliance. Based on the emission testing
conducted in 2011 and 2012, three of the eight glass-melting furnaces
would need to reduce their emissions to meet the proposed chromium
compound emission limits. We found that the use of a sodium hydroxide
scrubber is effective in reducing emissions of hexavalent chromium from
other industrial processes and that the technology can be transferred
to this industry sector. We estimated the capital cost for a sodium
hydroxide scrubber to be $250,000 and the total annualized costs,
including operating costs, to be $100,000.
    Costs are also incurred for compliance testing, monitoring,
recordkeeping, and reporting requirements of the proposed rule. Based
on the most recent test data provided, all eight glass-melting furnaces
currently meet the proposed PM emission limit.
    Because the scrubbers will be installed on three furnaces, the
industry-wide total capital investment will be $750,000. We estimate
that the total annualized cost of these controls will be $300,000, in
2011 dollars. The annual performance testing costs are $10,000 per gas-
fired glass-melting furnace. Since there are a total of eight gas-fired
glass-melting furnaces at the five facilities, the total annual testing
cost is $80,000. The estimated HAP reduction is 50 pounds of chromium
compounds resulting in overall cost effectiveness of $7,600 per pound
of HAP reduced.
    While we do not anticipate the construction of any new wool
fiberglass manufacturing facilities in the next 5 years, we do expect
most, if not all, of the 10 major source facilities to convert to non-
HAP binders and become area sources. However, we did not estimate new
source cost impacts for any additional facilities to avoid double
counting the costs associated with the major source rule (subpart NNN)
with similar gas-fired glass-melting furnace requirements. Table 5
below presents the costs to wool fiberglass area sources.

  Table 5--Estimated Costs and Reductions for the Proposed Wool Fiberglass Manufacturing Area Source Standards
                                               (NN) in This Action
----------------------------------------------------------------------------------------------------------------
                                      Est.      Est. total
       Proposed amendment           capital     annualized  Total HAP emissions  Cost effectiveness     Number
                                   cost ($MM)   cost ($MM)       reductions                           facilities
----------------------------------------------------------------------------------------------------------------
Installation of NaOH scrubber...     0.25 x 3      0.1 x 3  50 pounds per year.  7,600 ($ per                  2
                                                                                pound).

Additional testing and                      0     0.01 x 8  N/A................                                5
 monitoring for glass-melting
 furnaces.
----------------------------------------------------------------------------------------------------------------

    The analysis is documented in the memorandum, Costs and Emission
Reductions for the Proposed Wool Fiberglass Manufacturing NESHAP--Area
Sources, and is available in the docket.

C. What are the non-air quality health, environmental and energy
impacts for the proposed Wool Fiberglass Manufacturing area source
rule?

    We anticipate that three gas-fired glass-melting furnaces would
need to apply additional controls to meet the proposed chromium
emission limits. These controls, sodium hydroxide scrubbers, use water.
We estimate an annual requirement of 4.8 million gallons per year of
additional wastewater would be generated as a result of additional
water used for scrubbers.
    The energy impacts associated with meeting the proposed emission
limits would consist primarily of additional electricity needs to run
added or improved air pollution control devices. By our estimate, we
anticipate that an additional 1,000 megawatt-hours per year would be
required for the additional and improved control devices.
    We anticipate the secondary air impacts from adding controls to
meet the standards to be minimal. The combustion of fuel needed to
generate additional electricity would yield slight increases in
NOX, CO, SO2 emissions. Since NOX and
SO2 emissions and electric generating units are covered by
capped emissions trading programs, we do not estimate an increase in
secondary air impacts for these pollutants for this rule form
additional electricity demand. The combustion of additional fuel from
additional electrical usage and supplemental fuel for incineration
devices would yield CO emissions of less than 0.1 tpy. The analyses are
documented in the memorandum, Secondary Impacts of the Proposed Wool
Fiberglass Manufacturing NESHAP--Area Sources, which is available in
the docket.

D. What are the economic impacts of the proposed Wool Fiberglass
Manufacturing area source rule?

    We performed an economic impact analysis for wool fiberglass
consumers and producers nationally, using the annual compliance costs
estimated for this proposed rule. The impacts to producers affected by
this proposed rule are annualized costs of less than 0.01 percent of
their revenues, using the most current year available for revenue data.
Prices and output for wool fiberglass products should increase by no
more than the impact on cost to revenues for producers; thus, wool
fiberglass prices should increase by less than 0.01 percent. Hence, the
overall economic impact of this proposed rule should be low on the
affected industries and their consumers. For more information, please
refer to the Economic Impact and Small Business Analysis for this
proposed rulemaking that is in the docket (EPA-HQ-OAR-2010-1042).

VI. What are the proposed changes to Mineral Wool Production (Subpart
DDD) and Wool Fiberglass Manufacturing (Subpart NNN) major source
rules?

    On November 25, 2011, the EPA proposed revisions to the Mineral
Wool and the Wool Fiberglass Manufacturing NESHAP, 40 CFR part 63,
subparts DDD and NNN, respectively, to address the results of the
residual risk and technology review (RTR) that the EPA is required to
conduct under sections 112(d)(6) and 112(f)(2)(76 FR 72812). Today's
notice also proposes several revisions, corrections and clarifications
to that proposal.

A. Subpart DDD--Mineral Wool Production Major Source Rule

    Based on comments on the November 2011 proposal and new data
supplied by the industry, we are proposing the following revisions to
the major source rule amendments:
    (1) In response to the limits proposed on November 25, 2011, we
received raw material content information from the seven facilities
producing mineral wool in the U.S. Of the seven facilities, three
reported using slag and four reported only using minerals (rock) and
coke (e.g., ``no slag''). Slag is a waste by-product from the iron and
steel industry and is location-specific depending on the type of
facility/process generating the slag. Some slags have residual
fluorides or chlorides which vary from location to location and from
process to process. In response to this information, we are proposing
to subcategorize the mineral wool cupolas into two categories: Those
that process slag materials and those that do not. Based on this
subcategorization, we are proposing revised standards for HCl and HF.
    The revised limits being proposed today are summarized in Table 6
below:

                          Table 6--HCl and HF Emission Limits for Mineral Wool Cupolas
                                                [lb/ton of melt]
----------------------------------------------------------------------------------------------------------------
                                                                                2013 Proposed
                                                                             2013 Proposed         limit for
                                                         2011 Proposed         limit for      existing, new, and
                      Pollutant                          limit for all    existing, new, and     reconstructed
                                                            cupolas          reconstructed     cupolas not using
                                                                          cupolas using slag         slag
----------------------------------------------------------------------------------------------------------------
HCl.................................................              0.0096                0.21                0.43
HF..................................................               0.014                0.16                0.13
----------------------------------------------------------------------------------------------------------------

     (2) We are also proposing revised COS emission limits for cupolas
based on additional information regarding cupola design supported by
test data provided by industry in their comments on the November 2011
proposal. In response to the information provided, we are proposing to
subcategorize cupolas into closed-top and open-top cupolas. The revised
COS emission limits being proposed in this action are summarized in
Table 7 below:

                              Table 7--COS Emission Limits for Mineral Wool Cupolas
                                                [lb/ton of melt]
----------------------------------------------------------------------------------------------------------------
                                                                             2011 Proposed       2013 Proposed
                                     2011 Proposed       2013 Proposed     limit for new and   limit for new and
               COS                limit for existing  limit for existing     reconstructed       reconstructed
                                        cupolas             cupolas             cupolas             cupolas
----------------------------------------------------------------------------------------------------------------
Closed-Top......................                 3.3                 3.4               0.017               0.025
Open-Top........................                 3.3                 6.8               0.017                 4.3
----------------------------------------------------------------------------------------------------------------

     (3) The formaldehyde, phenol, and methanol emission limits for
combined collection/curing operations proposed on November 25, 2011,
have been revised based on comments and additional facility
information. The revised limits being proposed in this action are
summarized in Table 8 below. As a result of new test data, limits for
vertical and drum collection/curing would increase compared to the
limits previously proposed on November 25, 2011.

  Table 8--Emission Limits for Mineral Wool Combined Collection/Curing
                               Operations
                            [lb/ton of melt]
------------------------------------------------------------------------
                                         2011 Proposed    2013 Proposed
                                             limit            limit
------------------------------------------------------------------------
Curing & Drum Collection
    Formaldehyde......................          0.067              0.18
    Phenol............................          0.0023             1.3
    Methanol..........................          0.00077            0.48
Curing & Vertical Collection
    Formaldehyde......................          0.46               2.7
    Phenol............................          0.52               0.74
    Methanol..........................          0.63               1.0
Curing & Horizontal Collection
    Formaldehyde......................          0.054              0.054
    Phenol............................          0.15               0.15
    Methanol..........................          0.022              0.022
------------------------------------------------------------------------

    The updated draft risk assessment, located in the docket for this
rulemaking, is based on actual emissions currently emitted by the
industry. Due to new formaldehyde emissions data that were provided by
the industry our estimate of risk from actual emissions has increased
slightly compared to the risk assessment conducted for the November 25,
2011, proposal. The risk from mineral wool production is driven by
formaldehyde. The MIR at proposal for actual baseline emissions was 4-
in-1 million. The allowable MIR was estimated to be 10-in-1 million.
The post control emissions MIR was estimated to be 4-in-1 million.
    The actual MIR increased to 10-in-1 million, acute noncancer HQ
increased from eight to 22 and the AEGL-1 increased from 0.4 to 1.1
based on the new test data characterizing actual emissions. While the
risk increased slightly, we note that it is still very low, is
evaluated using conservative methods, and is still well within a level
we consider acceptable (that is, less than 100-in-1 million).
    (4) We are proposing definitions for open-top cupolas, closed-top
cupolas and slag.
    (5) The Part 63 GP have been amended seven times since they were
first promulgated in 1994 (59 FR 12430), and subpart DDD cites to the
GP requirements as they appeared in 1999. As a result, numerous
citations to the GP appear in subpart DDD that have since changed. In
today's action, we propose technical corrections to GP citations to
accurately reflect the GP as they now appear.
    (6) In response to industry comments we are proposing to remove the
requirement for PM testing by EPA method 202 contained in the original
proposal. The PM emission limits were based on testing that measured
only filterable particulate. Including Method 202 as a required test
method would measure condensible particulate, which was not accounted
for in determining the PM limit.

B. Subpart NNN--Wool Fiberglass Manufacturing Major Source Rule

    Based on comments on the November 2011 proposal and new data
supplied by the industry, we are proposing the following revisions to
the major source rule amendments:
    (1) At the time of the November 25, 2011 proposal, we proposed that
all glass-melting furnaces (electric or gas-fired) located at major
sources would be subject to the limit for chromium compounds we
proposed pursuant to 112(d)(6) and (f)(2). However, because of
information we have developed since the November 25 proposal, we are
now only proposing to apply the chromium emissions limit for glass-
melting furnaces to furnaces fired with gas. This would include
oxyfuel, recuperative air gas, air gas, and hybrid electric and air gas
furnaces. Comments received indicated that a separate chromium limit is
not necessary for electric furnaces. (See section IV.A of this preamble
for more information) Gas-fired glass-melting furnaces would be
required to limit their emissions of

chromium compounds to no more than 0.06 pounds of chromium compounds