National Emission Standards for Aerospace Manufacturing and Rework Facilities Risk and Technology Review, 8391-8439 [2015-02055]

Agencies

• ENVIRONMENTAL PROTECTION AGENCY

[Federal Register Volume 80, Number 31 (Tuesday, February 17, 2015)]
[Proposed Rules]
[Pages 8391-8439]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2015-02055]



[[Page 8391]]

Vol. 80

Tuesday,

No. 31

February 17, 2015

Part II





Environmental Protection Agency





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40 CFR Part 63





National Emission Standards for Aerospace Manufacturing and Rework 
Facilities Risk and Technology Review; Proposed Rule

Federal Register / Vol. 80 , No. 31 / Tuesday, February 17, 2015 / 
Proposed Rules

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 63

[EPA-HQ-OAR-2014-0830; FRL-9922-10-OAR]
RIN 2060-AQ99


National Emission Standards for Aerospace Manufacturing and 
Rework Facilities Risk and Technology Review

AGENCY: Environmental Protection Agency.

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing 
amendments to the national emissions standards for hazardous air 
pollutants (NESHAP) for Aerospace Manufacturing and Rework Facilities 
to address the results of the residual risk and technology review (RTR) 
conducted as required under the Clean Air Act (CAA), and to correct 
errors and deficiencies identified during the review of these 
standards. The proposed amendments would add limitations to reduce 
organic and inorganic emissions of hazardous air pollutants (HAP) from 
specialty coating application operations; would remove the exemptions 
from the emission limitations for periods of startup, shutdown and 
malfunction (SSM) so that affected units would be subject to the 
emission standards at all times; and would revise provisions to address 
recordkeeping and reporting requirements applicable to periods of SSM. 
This action also proposes other technical corrections. The EPA 
estimates that implementation of this proposed rule will result in 
reductions of 58 tons of HAP.

DATES: Comments. Comments must be received on or before April 3, 2015. 
A copy of comments on the information collection provisions should be 
submitted to the Office of Management and Budget (OMB) on or before 
March 19, 2015.
    Public Hearing. If anyone contacts the EPA requesting a public 
hearing by February 23, 2015, we will hold a public hearing on March 4, 
2015. If you are interested in requesting a public hearing or attending 
the public hearing, contact Ms. Pamela Garrett at (919) 541-7966 or at 
garrett.pamela@epa.gov. If the EPA holds a public hearing, the EPA will 
keep the record of the hearing open for 30 days after completion of the 
hearing to provide an opportunity for submission of rebuttal and 
supplementary information.

ADDRESSES: Comments. Submit your comments, identified by Docket ID No. 
EPA-HQ-OAR-2014-0830, by one of the following methods:
     Federal eRulemaking Portal: https://www.regulations.gov. 
Follow the online instructions for submitting comments.
     Email: A-and-R-Docket@epa.gov. Include Attention Docket ID 
No. EPA-HQ-OAR-2014-0830 in the subject line of the message.
     Fax: (202) 566-9744, Attention Docket ID No. EPA-HQ-OAR-
2014-0830.
     Mail: Environmental Protection Agency, EPA Docket Center 
(EPA/DC), Mail Code 28221T, Attention Docket ID No. EPA-HQ-OAR-2014-
0830, 1200 Pennsylvania Avenue NW., Washington, DC 20460. 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 (OMB), Attn: Desk Officer for EPA, 725 17th 
Street NW., Washington, DC 20503.
     Hand/Courier Delivery: EPA Docket Center, Room 3334, EPA 
WJC West Building, 1301 Constitution Avenue NW., Washington, DC 20004, 
Attention Docket ID No. EPA-HQ-OAR-2014-0830. 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 to Docket ID No. EPA-HQ-OAR-
2014-0830. The EPA's policy is that all comments received will be 
included in the public docket without change and may be made available 
online at https://www.regulations.gov, including any personal 
information provided, unless the comment includes information claimed 
to be confidential business information (CBI) or other information 
whose disclosure is restricted by statute. Do not submit information 
that you consider to be CBI or otherwise protected through https://www.regulations.gov or email. The https://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 https://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 not include special characters or 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: https://www.epa.gov/dockets.
    Docket. The EPA has established a docket for this rulemaking under 
Docket ID No. EPA-HQ-OAR-2014-0830. All documents in the docket are 
listed in the https://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, is not placed on the Internet 
and will be publicly available only in hard copy. Publicly available 
docket materials are available either electronically in regulations.gov 
or in hard copy at the EPA Docket Center, Room 3334, EPA WJC West 
Building, 1301 Constitution Avenue 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 EPA 
Docket Center is (202) 566-1742.
    Public Hearing. If a public hearing is requested by February 23, 
2015, it will be held on March 4, 2015 at the EPA's Research Triangle 
Park Campus, 109 T.W. Alexander Drive, Research Triangle Park, NC 
27711. The hearing will convene at 10:00 a.m. (Eastern Standard Time) 
and end at 5:00 p.m. (Eastern Standard Time). A lunch break will be 
held from 12:00 p.m. (Eastern Standard Time) until 1:00 p.m. (Eastern 
Standard Time). Please contact Ms. Pamela Garrett at (919) 541-7966 or 
at garrett.pamela@epa.gov 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 March 2, 2015.
    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 you 
require an accommodation, we ask that you preregister for the hearing, 
as we may not be able to arrange such

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accommodations without advance notice.
    If no one contacts the EPA requesting a public hearing to be held 
concerning this proposed rule by February 23, 2015, a public hearing 
will not take place. 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 the hearing will be held 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. Please note that the 
REAL ID Act, passed by Congress in 2005, established new requirements 
for entering federal facilities. If your driver's license is issued by 
Alaska, American Samoa, Arizona, Kentucky, Louisiana, Maine, 
Massachusetts, Minnesota, Montana, New York, Oklahoma or the state of 
Washington, you must present an additional form of identification to 
enter the federal building. Acceptable alternative forms of 
identification include: federal employee badges, passports, enhanced 
driver's licenses and military identification cards. 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. 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. 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. Again, a hearing will not be held 
unless requested.

FOR FURTHER INFORMATION CONTACT: For questions about this proposed 
action, contact Kim Teal, Sector Policies and Programs Division (D243-
02), Office of Air Quality Planning and Standards, U.S. Environmental 
Protection Agency, Research Triangle Park, North Carolina 27711; 
telephone number: (919) 541-5580; fax number: (919) 541-5450; and email 
address: teal.kim@epa.gov. For specific information regarding the risk 
modeling methodology, contact Ted Palma, Health and Environmental 
Impacts Division (C539-02), Office of Air Quality Planning and 
Standards, U.S. Environmental Protection Agency, Research Triangle 
Park, North Carolina 27711; telephone number: (919) 541-5470; fax 
number: (919) 541-0840; and email address: palma.ted@epa.gov. For 
information about the applicability of the NESHAP to a particular 
entity, contact Rafael Sanchez, Office of Enforcement and Compliance 
Assurance (OECA), (202) 564-7028, sanchez.rafael@epa.gov.

SUPPLEMENTARY INFORMATION: 
    Preamble Acronyms and Abbreviations. We use multiple acronyms and 
terms in this preamble. While this list may not be exhaustive, to ease 
the reading of this preamble and for reference purposes, the EPA 
defines the following terms and acronyms here:

AD Airworthiness Directive
AEGL acute exposure guideline level
AERMOD air dispersion model used by the HEM-3 model
ATSDR Agency for Toxic Substances and Disease Registry
BACT Best Achievable Control Technology
CAA Clean Air Act
CalEPA California EPA
CBI Confidential Business Information
CDX EPA's Central Data Exchange
CEDRI EPA's Compliance and Emissions Data Reporting Interface
CFR Code of Federal Regulations
CTG Control Technique Guideline document
EJ environmental justice
EPA Environmental Protection Agency
ERPG Emergency Response Planning Guidelines
ERT EPA's Electronic Reporting Tool
FAA Federal Aviation Administration
FR Federal Register
g/L grams/liter
HAP hazardous air pollutants
HCl hydrochloric acid
HEM-3 Human Exposure Model, Version 1.1.0
HF hydrogen fluoride
HI hazard index
HQ hazard quotient
HVLP high volume low pressure
IARC International Agency for Research on Cancer
ICR information collection request
IRIS Integrated Risk Information System
km kilometer
lb/gal pounds/gallon
LOAEL Lowest-observed-adverse-effect level
MACT maximum achievable control technology
mg/m\3\ milligrams per cubic meter
MIR maximum individual risk
mm Hg millimeters mercury
NAAQS National Ambient Air Quality Standards
NAICS North American Industry Classification System
NAS National Academy of Sciences
NATA National Air Toxics Assessment
NEI National Emission Inventory
NESHAP National Emissions Standards for Hazardous Air Pollutants
NOAA National Oceanic and Atmospheric Administration
NOAEL No-observed-adverse-effect levels
NRC National Research Council
NRDC Natural Resources Defense Council
NTP National Toxicology Program
NTTAA National Technology Transfer and Advancement Act
OAQPS Office of Air Quality Planning and Standards
OECA Office of Enforcement and Compliance Assurance
OEM original equipment manufacturer
OMB Office of Management and Budget
PAH polycyclic aromatic hydrocarbons
PB-HAP hazardous air pollutants known to be persistent and bio-
accumulative in the environment
PEL Probable effect level
POM polycyclic organic matter
ppm parts per million
PSD Prevention of Significant Deterioration
RACT Reasonably Available Control Technology
RBLC EPA's RACT/BACT/LAER Clearinghouse
RCRA Resource Conservation and Recovery Act of 1976
REL reference exposure level
RFA Regulatory Flexibility Act
RfC reference concentration
RfD reference dose
RoC Report of the Carcinogens
RTR residual risk and technology review
SAB Science Advisory Board
SCAQMD South Coast Air Quality Management District
SSM startup, shutdown and malfunction
TOSHI target organ-specific hazard index
tpy tons per year
TRIM.FaTE Total Risk Integrated Methodology.Fate, Transport, and 
Ecological Exposure model
TTN Technology Transfer Network
UF uncertainty factor
[mu]g/m\3\ microgram per cubic meter
UMRA Unfunded Mandates Reform Act
URE unit risk estimate
VOC volatile organic compounds

    Organization of this Document. The information in this preamble is 
organized as follows:

I. General Information
    A. Does this action apply to me?
    B. Where can I get a copy of this document and other related 
information?
    C. What should I consider as I prepare my comments for the EPA?
II. Background
    A. What is the statutory authority for this action?

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    B. What is this source category and how does the current NESHAP 
regulate its HAP emissions?
    C. What data collection activities were conducted to support 
this action?
    D. What other relevant background information and data are 
available?
    E. What litigation is related to this proposed action?
III. Analytical Procedures
    A. How did we estimate post-MACT risks posed by the source 
category?
    B. How did we consider the risk results in making decisions for 
this proposal?
    C. How did we perform the technology review?
IV. Analytical Results and Proposed Decisions
    A. What actions are we taking pursuant to CAA sections 112(d)(2) 
and 112(d)(3)?
    B. What are the results of the risk assessment and analyses?
    C. What are our proposed decisions regarding risk acceptability, 
ample margin of safety and adverse environmental effects?
    D. What are the results and proposed decisions based on our 
technology review?
    E. What other actions are we proposing?
    F. What compliance dates are we proposing?
V. Summary of Cost, Environmental and Economic Impacts
    A. What are the affected sources?
    B. What are the air quality impacts?
    C. What are the cost impacts?
    D. What are the economic impacts?
    E. What are the benefits?
VI. Request for Comments
VII. Submitting Data Corrections
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 (RFA)
    D. Unfunded Mandates Reform Act (UMRA)
    E. Executive Order 13132: Federalism
    F. Executive Order 13175: Consultation and Coordination with 
Indian Tribal Governments
    G. Executive Order 13045: Protection of Children from 
Environmental Health Risks and Safety Risks
    H. Executive Order 13211: Actions Concerning Regulations That 
Significantly Affect Energy Supply, Distribution or Use
    I. National Technology Transfer and Advancement Act (NTTAA)
    J. Executive Order 12898: Federal Actions to Address 
Environmental Justice in Minority Populations and Low-Income 
Populations

I. General Information

A. Does this action apply to me?

    Table 1 of this preamble lists the regulated industrial source 
category that is the subject of this proposal. Table 1 is not intended 
to be exhaustive, but rather to provide a guide for readers regarding 
the entities that this proposed action is likely to affect. The 
proposed standards, once promulgated, will be directly applicable to 
the affected sources. Federal government entities may be affected by 
this proposed action. Parties potentially affected by this action 
include major and synthetic minor source installations that are owned 
or operated by the Armed Forces of the United States (including the 
Department of Defense and the Coast Guard) and the National Aeronautics 
and Space Administration. As defined under the ``Surface Coating'' 
industry sector in the ``Initial List of Categories of Sources Under 
Section 112(c)(1) of the Clean Air Act Amendments of 1990'' (see 57 FR 
31576, July 16, 1992), the Aerospace Manufacturing and Rework 
Facilities source category is any facility engaged, either in part or 
in whole, in the manufacture or rework of commercial, civil or military 
aerospace vehicles or components and that are major sources as defined 
in 40 CFR 63.2.

  Table 1--Industrial Source Category Affected by This Proposed Action
------------------------------------------------------------------------
       Source Category               NESHAP            NAICS code \a\
------------------------------------------------------------------------
Aerospace Manufacturing and   Aerospace             336411, 336412,
 Rework Facilities.            Manufacturing and     336413, 336414,
                               Rework Facilities.    336415, 336419,
                                                     481111, 481112,
                                                     481211, 481212,
                                                     481219.
------------------------------------------------------------------------
\a\ North American Industry Classification System.

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

    In addition to being available in the docket, an electronic copy of 
this action is available on the Internet through the EPA's Technology 
Transfer Network (TTN) Web site, a forum for information and technology 
exchange in various areas of air pollution control. Following signature 
by the EPA Administrator, the EPA will post a copy of this proposed 
action at: https://www.epa.gov/ttn/atw/aerosp/aeropg.html. Following 
publication in the Federal Register, the EPA will post the Federal 
Register version of the proposal and key technical documents at this 
same Web site. Information on the overall residual risk and technology 
review program is available at the following Web site: https://www.epa.gov/ttn/atw/rrisk/rtrpg.html.

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 https://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 comments that includes information claimed 
as CBI, you must submit a copy of the comments that does not contain 
the information claimed as CBI 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 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 Code of Federal Regulations (CFR) part 2. Send or deliver 
information identified as CBI only to the following address: OAQPS 
Document Control Officer (C404-02), OAQPS, U.S. Environmental 
Protection Agency, Research Triangle Park, North Carolina 27711, 
Attention Docket ID No. EPA-HQ-OAR-2014-0830.

II. Background

A. What is the statutory authority for this action?

    Section 112 of the CAA establishes a two-stage regulatory process 
to address emissions of HAP from stationary sources. In the first 
stage, after the EPA has identified categories of sources emitting one 
or more of the HAP listed in CAA section 112(b), CAA section 112(d) 
requires us to promulgate technology-based NESHAP for those

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sources. ``Major sources'' are those that emit or have the potential to 
emit 10 tons per year (tpy) or more of a single HAP or 25 tpy or more 
of any combination of HAP. For major sources, the technology-based 
NESHAP must reflect the maximum degree of emission reductions of HAP 
achievable (after considering cost, energy requirements and non-air 
quality health and environmental impacts) and are commonly referred to 
as maximum achievable control technology (MACT) standards.
    MACT standards must reflect the maximum degree of emissions 
reduction achievable through the application of measures, processes, 
methods, systems or techniques, including, but not limited to, measures 
that: (1) Reduce the volume of or eliminate pollutants through process 
changes, substitution of materials or other modifications; (2) enclose 
systems or processes to eliminate emissions; (3) capture or treat 
pollutants when released from a process, stack, storage or fugitive 
emissions point; (4) are design, equipment, work practice or 
operational standards (including requirements for operator training or 
certification); or (5) are a combination of the above. CAA section 
112(d)(2)(A) through (E). The MACT standards may take the form of 
design, equipment, work practice or operational standards where the EPA 
first determines either that: (1) A pollutant cannot be emitted through 
a conveyance designed and constructed to emit or capture the pollutant, 
or that any requirement for or use of, such a conveyance would be 
inconsistent with law; or (2) the application of measurement 
methodology to a particular class of sources is not practicable due to 
technological and economic limitations. CAA section 112(h)(1) and (2).
    The MACT ``floor'' is the minimum control level allowed for MACT 
standards promulgated under CAA section 112(d)(3) and may not be based 
on cost considerations. For new sources, the MACT floor cannot be less 
stringent than the emissions control that is achieved in practice by 
the best-controlled similar source. The MACT floor for existing sources 
can be less stringent than floors for new sources, but not less 
stringent than the average emissions limitation achieved by the best-
performing 12 percent of existing sources in the category or 
subcategory (or the best-performing five sources for categories or 
subcategories with fewer than 30 sources). In developing MACT 
standards, the EPA must also consider control options that are more 
stringent than the floor. We may establish standards more stringent 
than the floor based on considerations of the cost of achieving the 
emission reductions, any non-air quality health and environmental 
impacts and energy requirements.
    The EPA is then required to review these technology-based standards 
and revise them ``as necessary (taking into account developments in 
practices, processes and control technologies)'' no less frequently 
than every 8 years. CAA section 112(d)(6). In conducting this review, 
the EPA is not required to recalculate the MACT floor. Natural 
Resources Defense Council (NRDC) v. EPA, 529 F.3d 1077, 1084 (D.C. Cir. 
2008). Association of Battery Recyclers, Inc. v. EPA, 716 F.3d 667 
(D.C. Cir. 2013).
    The second stage in standard-setting focuses on reducing any 
remaining (i.e., ``residual'') risk according to CAA section 112(f). 
CAA Section 112(f)(1) required that the EPA prepare a report to 
Congress discussing (among other things) methods of calculating the 
risks posed (or potentially posed) by sources after implementation of 
the MACT standards, the public health significance of those risks and 
the EPA's recommendations as to legislation regarding such remaining 
risk. The EPA prepared and submitted the Residual Risk Report to 
Congress, EPA-453/R-99-001 (Risk Report) in March 1999. CAA section 
112(f)(2) then provides that if Congress does not act on any 
recommendation in the Risk Report, the EPA must analyze and address 
residual risk for each category or subcategory of sources 8 years after 
promulgation of such standards pursuant to CAA section 112(d).
    Section 112(f)(2) of the CAA requires the EPA to determine for 
source categories subject to MACT standards whether the emission 
standards provide an ample margin of safety to protect public health. 
Section 112(f)(2)(B) of the CAA expressly preserves the EPA's use of 
the two-step process for developing standards to address any residual 
risk and the agency's interpretation of ``ample margin of safety'' 
developed in the National Emissions Standards for Hazardous Air 
Pollutants: Benzene Emissions from Maleic Anhydride Plants, 
Ethylbenzene/Styrene Plants, Benzene Storage Vessels, Benzene Equipment 
Leaks, and Coke By-Product Recovery Plants (Benzene NESHAP) (54 FR 
38044, September 14, 1989). The EPA notified Congress in the Risk 
Report that the agency intended to use the Benzene NESHAP approach in 
making CAA section 112(f) residual risk determinations (EPA-453/R-99-
001, p. ES-11). The EPA subsequently adopted this approach in its 
residual risk determinations and in a challenge to the risk review for 
the Synthetic Organic Chemical Manufacturing source category, the 
United States Court of Appeals for the District of Columbia Circuit 
upheld as reasonable the EPA's interpretation that subsection 112(f)(2) 
incorporates the approach established in the Benzene NESHAP. See NRDC 
v. EPA, 529 F.3d 1077, 1083 (D.C. Cir. 2008) (``[S]ubsection 
112(f)(2)(B) expressly incorporates the EPA's interpretation of the 
Clean Air Act from the Benzene standard, complete with a citation to 
the Federal Register.''); see also A Legislative History of the Clean 
Air Act Amendments of 1990, vol. 1, p. 877 (Senate debate on Conference 
Report).
    The first step in the process of evaluating residual risk is the 
determination of acceptable risk. If risks are unacceptable, the EPA 
cannot consider cost in identifying the emissions standards necessary 
to bring risks to an acceptable level. The second step is the 
determination of whether standards must be further revised in order to 
provide an ample margin of safety to protect public health. The ample 
margin of safety is the level at which the standards must be set, 
unless an even more stringent standard is necessary to prevent, taking 
into consideration costs, energy, safety and other relevant factors, an 
adverse environmental effect.
1. Step 1--Determination of Acceptability
    The agency in the Benzene NESHAP concluded that ``the acceptability 
of risk under section 112 is best judged on the basis of a broad set of 
health risk measures and information'' and that the ``judgment on 
acceptability cannot be reduced to any single factor.'' Benzene NESHAP 
at 38046. The determination of what represents an ``acceptable'' risk 
is based on a judgment of ``what risks are acceptable in the world in 
which we live'' (Risk Report at 178, quoting NRDC v. EPA, 824 F. 2d 
1146, 1165 (D.C. Cir. 1987) (en banc) (``Vinyl Chloride''), recognizing 
that our world is not risk-free.
    In the Benzene NESHAP, we stated that ``EPA will generally presume 
that if the risk to [the maximum exposed] individual is no higher than 
approximately one in 10 thousand, that risk level is considered 
acceptable.'' 54 FR 38045, September 14, 1989. We discussed the maximum 
individual lifetime cancer risk (or maximum individual risk (MIR)) as 
being ``the estimated risk that a person living near a plant would have 
if he or she were

[[Page 8396]]

exposed to the maximum pollutant concentrations for 70 years.'' Id. We 
explained that this measure of risk ``is an estimate of the upper bound 
of risk based on conservative assumptions, such as continuous exposure 
for 24 hours per day for 70 years.'' Id. We acknowledged that maximum 
individual lifetime cancer risk ``does not necessarily reflect the true 
risk, but displays a conservative risk level which is an upper-bound 
that is unlikely to be exceeded.'' Id.
    Understanding that there are both benefits and limitations to using 
the MIR as a metric for determining acceptability, we acknowledged in 
the Benzene NESHAP that ``consideration of maximum individual risk * * 
* must take into account the strengths and weaknesses of this measure 
of risk.'' Id. Consequently, the presumptive risk level of 100-in-1 
million (1-in-10 thousand) provides a benchmark for judging the 
acceptability of maximum individual lifetime cancer risk, but does not 
constitute a rigid line for making that determination. Further, in the 
Benzene NESHAP, we noted that:

[p]articular attention will also be accorded to the weight of 
evidence presented in the risk assessment of potential 
carcinogenicity or other health effects of a pollutant. While the 
same numerical risk may be estimated for an exposure to a pollutant 
judged to be a known human carcinogen, and to a pollutant considered 
a possible human carcinogen based on limited animal test data, the 
same weight cannot be accorded to both estimates. In considering the 
potential public health effects of the two pollutants, the Agency's 
judgment on acceptability, including the MIR, will be influenced by 
the greater weight of evidence for the known human carcinogen.

    Id. at 38046. The agency also explained in the Benzene NESHAP that:

[i]n establishing a presumption for MIR, rather than a rigid line 
for acceptability, the Agency intends to weigh it with a series of 
other health measures and factors. These include the overall 
incidence of cancer or other serious health effects within the 
exposed population, the numbers of persons exposed within each 
individual lifetime risk range and associated incidence within, 
typically, a 50 km exposure radius around facilities, the science 
policy assumptions and estimation uncertainties associated with the 
risk measures, weight of the scientific evidence for human health 
effects, other quantified or unquantified health effects, effects 
due to co-location of facilities, and co-emission of pollutants.

    Id. at 38045. In some cases, these health measures and factors 
taken together may provide a more realistic description of the 
magnitude of risk in the exposed population than that provided by 
maximum individual lifetime cancer risk alone.
    As noted earlier, in NRDC v. EPA, the court held that CAA section 
112(f)(2) ``incorporates the EPA's interpretation of the Clean Air Act 
from the Benzene Standard.'' The court further held that Congress' 
incorporation of the Benzene standard applies equally to carcinogens 
and non-carcinogens. 529 F.3d at 1081-82. Accordingly, we also consider 
non-cancer risk metrics in our determination of risk acceptability and 
ample margin of safety.
2. Step 2--Determination of Ample Margin of Safety
    CAA section 112(f)(2) requires the EPA to determine, for source 
categories subject to MACT standards, whether those standards provide 
an ample margin of safety to protect public health. As explained in the 
Benzene NESHAP, ``the second step of the inquiry, determining an `ample 
margin of safety,' again includes consideration of all of the health 
factors, and whether to reduce the risks even further . . . Beyond that 
information, additional factors relating to the appropriate level of 
control will also be considered, including costs and economic impacts 
of controls, technological feasibility, uncertainties and any other 
relevant factors. Considering all of these factors, the agency will 
establish the standard at a level that provides an ample margin of 
safety to protect the public health, as required by section 112.'' 54 
FR 38046, September 14, 1989.
    According to CAA section 112(f)(2)(A), if the MACT standards for 
HAP ``classified as a known, probable, or possible human carcinogen do 
not reduce lifetime excess cancer risks to the individual most exposed 
to emissions from a source in the category or subcategory to less than 
one in one million,'' the EPA must promulgate residual risk standards 
for the source category (or subcategory), as necessary to provide an 
ample margin of safety to protect public health. In doing so, the EPA 
may adopt standards equal to existing MACT standards if the EPA 
determines that the existing standards (i.e., the MACT standards) are 
sufficiently protective. NRDC v. EPA, 529 F.3d 1077, 1083 (D.C. Cir. 
2008) (``If EPA determines that the existing technology-based standards 
provide an `ample margin of safety,' then the Agency is free to readopt 
those standards during the residual risk rulemaking.'') The EPA must 
also adopt more stringent standards, if necessary, to prevent an 
adverse environmental effect,\1\ but must consider cost, energy, safety 
and other relevant factors in doing so.
---------------------------------------------------------------------------

    \1\ ``Adverse environmental effect'' is defined as any 
significant and widespread adverse effect, which may be reasonably 
anticipated to wildlife, aquatic life or natural resources, 
including adverse impacts on populations of endangered or threatened 
species or significant degradation of environmental qualities over 
broad areas. See CAA section 112(a)(7).
---------------------------------------------------------------------------

    The CAA does not specifically define the terms ``individual most 
exposed,'' ``acceptable level'' and ``ample margin of safety.'' In the 
Benzene NESHAP, 54 FR 38044-38045, September 14, 1989, we stated as an 
overall objective:

In protecting public health with an ample margin of safety under 
section 112, EPA strives to provide maximum feasible protection 
against risks to health from hazardous air pollutants by (1) 
protecting the greatest number of persons possible to an individual 
lifetime risk level no higher than approximately 1-in-1 million and 
(2) limiting to no higher than approximately 1-in-10 thousand [i.e., 
100-in-1 million] the estimated risk that a person living near a 
plant would have if he or she were exposed to the maximum pollutant 
concentrations for 70 years.

    The agency further stated that ``[t]he EPA also considers incidence 
(the number of persons estimated to suffer cancer or other serious 
health effects as a result of exposure to a pollutant) to be an 
important measure of the health risk to the exposed population. 
Incidence measures the extent of health risks to the exposed population 
as a whole, by providing an estimate of the occurrence of cancer or 
other serious health effects in the exposed population.'' Id. at 38045.
    In the ample margin of safety decision process, the agency again 
considers all of the health risks and other health information 
considered in the first step, including the incremental risk reduction 
associated with standards more stringent than the MACT standard or a 
more stringent standard that EPA has determined is necessary to ensure 
risk is acceptable. In the ample margin of safety analysis, the agency 
considers additional factors, including costs and economic impacts of 
controls, technological feasibility, uncertainties and any other 
relevant factors. Considering all of these factors, the agency will 
establish the standard at a level that provides an ample margin of 
safety to protect the public health, as required by CAA section 112(f). 
54 FR 38046, September 14, 1989.

[[Page 8397]]

B. What is this source category and how does the current NESHAP 
regulate its HAP emissions?

1. Description of the Aerospace Manufacturing and Rework Facilities 
Source Category and Applicability.
    The NESHAP for the Aerospace Manufacturing and Rework Facilities 
source category (henceforth referred to as the ``Aerospace NESHAP'') 
was promulgated on September 1, 1995 (60 FR 45956) and codified at 40 
CFR part 63, subpart GG. As promulgated in 1995, the Aerospace NESHAP 
applies to the surface coating and related operations at each new and 
existing affected source of HAP emissions at facilities that are major 
sources and are engaged, either in part or in whole, in the manufacture 
or rework of commercial, civil or military aerospace vehicles or 
components. The requirements of the standards are nearly the same for 
both new and existing sources. The Aerospace NESHAP (40 CFR 63.742) 
defines ``aerospace vehicle or component'' as ``any fabricated part, 
processed part, assembly of parts or completed unit, with the exception 
of electronic components, of any aircraft, including, but not limited 
to airplanes, helicopters, missiles, rockets, and space vehicles.'' 
Today, we estimate that 144 facilities are subject to the Aerospace 
NESHAP. A complete list of facilities subject to the Aerospace NESHAP 
is available in the Aerospace RTR database, which is available for 
review in the docket for this proposed rulemaking. Section 63.741(c) 
defines each affected source in the Aerospace Manufacturing and Rework 
Facilities source category, and a facility could have a combination of 
both new and existing affected sources. However, the emission standards 
for new and existing affected sources are the same for nearly all 
operations within subpart GG. The exceptions are the filter efficiency 
requirements to control inorganic HAP emissions from primer and topcoat 
spray application operations in 40 CFR 63.745 and for dry media 
blasting operations in 40 CFR 63.746 and the requirements for controls 
to reduce organic HAP emissions from chemical depainting operations in 
40 CFR 63.746(c).
    The Aerospace NESHAP applies to organic HAP emissions from cleaning 
operations, depainting operations, primer application operations, 
topcoat application operations, chemical milling maskant application 
operations and the handling and storage of waste. The rule also applies 
to inorganic HAP emissions from primer and topcoat application 
operations using spray equipment and depainting operations using dry 
media blasting. The rule provides an exemption for primers, topcoats 
and chemical milling maskants used in low-volumes which is defined as 
189 liters (50 gallons) or less per formulation and for which the 
combined annual total does not exceed 757 liters (200 gallons).
    The current Aerospace NESHAP explicitly excludes specialty coatings 
from meeting any control requirements, as specified in 40 CFR 63.741(f) 
and in 40 CFR 63.742 (i.e., the definitions for ``exterior primer,'' 
``primer,'' and ``topcoat''). Appendix A of the Aerospace NESHAP 
defines 59 separate categories of specialty coatings.
    Although the EPA did not include emission limitations for specialty 
coatings in the Aerospace NESHAP finalized in 1995 or in any subsequent 
amendments, the EPA included VOC content limits for the 59 categories 
of specialty coatings in the 1997 Aerospace Control Techniques 
Guidelines (CTG) document.\2\ The CAA requires that state 
implementation plans (SIPs) for certain ozone nonattainment areas be 
revised to require the implementation of reasonably available control 
technology (RACT) to control volatile organic compounds (VOC) 
emissions. The EPA has defined RACT as the lowest emission limitation 
that a particular source is capable of meeting by the application of 
control technology that is reasonably available considering 
technological and economic feasibility. The Aerospace CTG is intended 
to provide state and local air pollution control authorities with an 
information base, recommended emissions limitations and monitoring, 
recordkeeping and reporting requirements for proceeding with their 
analyses of reasonably available control technology (RACT) for their 
own regulations to reduce VOC emissions from aerospace surface coating 
operations.
---------------------------------------------------------------------------

    \2\ Guideline Series: Control of Volatile Organic Compound 
Emissions from Coating Operations at Aerospace Manufacturing and 
Rework Operations. Emission Standards Division, U. S. Environmental 
Protection Agency, Office of Air and Radiation, Office of Air 
Quality Planning and Standards, Research Triangle Park, NC 27711, 
December 1997. Publication No. EPA-453/R-97-004.
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2. Organic and Inorganic HAP Emission Sources
    Organic HAP emissions from cleaning and depainting operations occur 
from the evaporation of the volatile portion of the cleaning solvents 
or chemical strippers. Cleaning emissions are typically fugitive in 
nature and occur at most processing steps. Emissions from depainting 
operations that occur within a booth or hangar are typically captured 
and exhausted through a stack, although some emissions may be fugitive 
in nature (e.g., open tanks).
    Organic HAP emissions from coating (primers, topcoats and chemical 
milling maskants) application operations occur from the evaporation of 
the solvent contained in the coatings. These emissions occur during the 
application of the coatings on aerospace vehicles or parts, which may 
take place in large open areas, such as hangars or in partially or 
fully enclosed spaces, such as within spray booths.
    Organic HAP emissions from waste occur from evaporation of the 
volatile portion of the waste while it is being handled or stored. 
These emissions are fugitive in nature, occurring from each waste 
container.
    Some coatings contain compounds that are inorganic HAP. Inorganic 
HAP emissions from coatings occur during the application of the coating 
if it is applied using spray guns. These inorganic HAP emissions are 
paint particulates, commonly referred to as ``overspray,'' that do not 
adhere to the surface being coated. Like the organic HAP emissions from 
the operations, the emissions of the inorganic HAP may occur in large 
open areas, such as hangars or in partially or fully enclosed spaces, 
such as within spray booths. However, coatings that contain inorganic 
HAP are typically applied in spray booths equipped with exhaust filters 
to capture paint overspray. Inorganic HAP are not emitted from coatings 
applied with non-spray methods, such as brushes, rollers or dip 
coating, because the coating is not atomized with these methods.
    Inorganic HAP emissions from depainting operations may occur from 
non-chemical methods, such as plastic and other types of dry media 
blasting, used to strip an aerospace vehicle. (Chemical stripping 
techniques do not release inorganic HAP.) These emissions occur as 
particulates generated during the blasting process. The operation is 
typically carried out within a large hangar equipped with a ventilation 
system and particulate filtration device (e.g., a baghouse) or in 
smaller enclosures, also equipped with filtration. The inorganic HAP 
that are released from the depainting operations are primarily found in 
the paint being stripped, although some stripping media may contain 
trace amounts of inorganic HAP.

[[Page 8398]]

3. Regulation of Organic and Inorganic HAP Emissions in the Aerospace 
NESHAP
    The Aerospace NESHAP specifies numerical emission limits for 
organic HAP emissions from primer, topcoat, chemical milling maskant 
application operations and chemical depainting operations; equipment 
and filter efficiency requirements for dry media blasting depainting 
operations and spray applied coating operations; composition 
requirements and equipment standards for cleaning operations; and work 
practice standards for waste handling and storage operations.
    The organic HAP emission rate for primers is 540 grams/liter (g/L) 
(4.5 pounds/gallon (lb/gal)) (less water) for general aviation rework 
facilities; 650 g/L (5.4 lb/gal) (less water) for large commercial 
aircraft; or 350 g/L (2.9 lb/gal) for other primers (40 CFR 
63.745(c)(1) and (2)). For topcoats and self-priming topcoats the 
emission rate is 420 g/L (3.5 lb/gal) (less water); and 540 g/L (4.5 
lb/gal) (less water) for primers and self-priming topcoats at general 
aviation rework facilities (40 CFR 63.745(c)(3) and (4)). 
Alternatively, a control system can be used to capture and control 
emissions from the primer or topcoat application operation (40 CFR 
63.745(d)). The system must achieve an overall control efficiency of 81 
percent. Further, the Aerospace NESHAP specifies which types of coating 
application techniques may be used (40 CFR 63.745(f)). The Aerospace 
NESHAP also provides operating requirements for the application of 
primers or topcoats that contain inorganic HAP, including control of 
spray booth exhaust streams with either particulate filters or 
waterwash systems (40 CFR 63.745(g)). The primer and topcoat limits and 
control requirements do not apply to specialty coatings defined in 
Appendix A to subpart GG.
    The organic HAP emission content limits for chemical milling 
maskants for use with Type I chemical milling solutions is 622 g/L (5.2 
lb/gal) (less water) and 160 g/L (1.3 lb/gal) (less water) for use with 
Type II chemical milling solutions (40 CFR 63.747(c)). Alternatively, a 
control system that achieves an overall control efficiency of 81 
percent can be used to capture and control emissions from the maskant 
application operation (40 CFR 63.747(d)). These requirements do not 
apply to touch-up of scratched surfaces or damaged maskant and touch-up 
of trimmed edges.
    For cleaning operations (including hand-wipe cleaning), the 
Aerospace NESHAP specifies that cleaning solvents meet certain 
composition requirements or that the cleaning solvents have a composite 
vapor pressure of no more than 45 millimeters mercury (mm Hg) (24.1 in. 
water) (40 CFR 63.744(b)). Work practice measures are also required (40 
CFR 63.744(a)). Four work practice alternative techniques are specified 
for spray gun cleaning, and work practice standards are specified for 
flush cleaning operations (40 CFR 63.744(c) and (d)).
    The Aerospace NESHAP also specifies requirements for depainting 
operations. Where there are no controls for organic HAP emissions from 
chemical depainting operations, the rule prohibits organic HAP 
emissions from chemical depainting operations, with the exception that 
26 gallons of HAP-containing chemical stripper (or alternatively 190 
pounds of organic HAP) may be used for each commercial aircraft 
stripped, or 50 gallons (or 365 pounds of organic HAP) for each 
military aircraft for spot stripping and decal removal (40 CFR 
63.746(b)(1) through (3)). Where there are controls for organic HAP 
emissions from chemical depainting, emissions must be reduced by 81 
percent for controls installed before the effective date, and by 95 
percent for controls installed on or after the effective date (40 CFR 
63.746(c)). For non-chemical depainting operations that generate 
inorganic HAP emissions from dry media blasting, the operation must be 
performed in an enclosed area or in a closed cycle depainting system 
and the air stream from the operation must pass through a dry filter 
system meeting a minimum efficiency specified in the rule, through a 
baghouse or through a waterwash system before being released to the 
atmosphere (40 CFR 63.746(b)(4)).
    The handling and storage of waste that contains HAP must be 
conducted in a manner that minimizes spills (40 CFR 63.748).

C. What data collection activities were conducted to support this 
action?

    In February 2011, the EPA issued an information collection request 
(ICR), pursuant to CAA section 114, to approximately 1,300 facilities 
that were thought to potentially own and operate Aerospace 
Manufacturing and Rework Facilities. Information was requested on 
operations subject to the Aerospace NESHAP (coatings, blast depainting 
operations, solvent depainting operations and solvent cleaning 
operations) as well as specialty coatings, chemical milling and metal 
finishing operations, composite processing, storage tanks and 
wastewater treatment. Information was also requested on booth 
characteristics and control devices and location coordinates (latitude 
and longitude) of emission stacks and operations. The ICR requested 
available information regarding coating and solvent usage, process 
equipment, control devices used, point and fugitive HAP emissions, 
practices used to control HAP emissions and other aspects of facility 
operations. A total of 87 major source facilities and 57 synthetic 
minor facilities responded to the survey and were included in the risk 
modeling analysis. The remaining facilities were either area source 
facilities, not aerospace manufacturing or rework facilities or closed 
facilities, or the ICR was returned undeliverable. We received data on 
coating and solvent usage, chemical milling, metal finishing, 
depainting operations, composite processing operations, storage tanks, 
wastewater treatment operations and use of add-on control devices. From 
these data, we were able to calculate HAP emissions for each of the 
major source and synthetic minor facilities that responded to the 
survey.
    In October 2012, the EPA issued a request for stack test data under 
the authority of section 114 of the CAA. This request was sent to 9 
parent companies for 18 facilities, requesting stack emissions testing 
data for selected coating operations and spray booths and blast 
depainting, composite processing and metal finishing operations 
believed to represent the various processes and capture and control 
configurations used by the industry. All facilities either responded to 
the survey or provided information indicating the operations for which 
we requested stack testing had been shutdown.
    In September 2013, the EPA issued an additional request to the same 
companies requesting supplemental testing to confirm the content of the 
coatings used in the October 2012 stack testing. These data were used 
to speciate emissions for individual coatings and to develop the 
default chromium speciation profile for processes included in the 2011 
ICR.
    In May 2014, the EPA solicited industry review of the EPA's draft 
modeling file records (e.g., estimated emissions and emission 
estimation methods) that were developed based on the results of the 
data collection efforts described above and the 2011 National Emission 
Inventory (NEI) and 2005 National Air Toxics Assessment (NATA) 
discussed in section II.D of this preamble. Of the 171 facilities 
contacted, 84 facilities responded. Of the 171 facilities contacted, 
the EPA determined that 144 are in operation

[[Page 8399]]

and subject to the NESHAP and 27 facilities are closed or not subject 
to the Aerospace NESHAP (e.g., are area sources). The 144 facilities 
that were determined to be in operation and subject to the NESHAP are 
included in the model input file for the risk assessment.

D. What other relevant background information and data are available?

    The 2011 NEI provided supplemental information for this RTR. The 
NEI is a database that contains information about sources that emit 
criteria air pollutants, their precursors and HAP. The database 
includes estimates of annual air pollutant emissions from point, 
nonpoint and mobile sources in the 50 states, the District of Columbia, 
Puerto Rico and the Virgin Islands. The EPA collects this information 
and releases an updated version of the NEI database every 3 years. The 
NEI includes information necessary for conducting risk modeling, 
including annual HAP emissions estimates from individual emission 
points at facilities and the related emissions release parameters. For 
each emission record that was needed for the model input file for the 
risk assessment (hereafter referred to as the ``RTR emissions 
dataset'') that was not available from the 2011 ICR responses, the EPA 
used available data in the 2011 NEI as the first alternative. The NEI 
emission records used included annual HAP emissions estimates for 
boilers, engines, chemical manufacturing processes, secondary metal 
production processes, heaters, soil remediation, transportation 
equipment, waste disposal, welding and other miscellaneous 
manufacturing processes that were not included in the 2011 ICR. 
Individual chromium emissions estimates were excluded from the modeling 
file if they were found to overlap with a regulated process.
    The 2005 NATA also provided supplemental data for the RTR emissions 
dataset for this RTR. The 2005 NATA includes annual HAP emissions 
estimates for three Aerospace Manufacturing and Rework Facilities that 
are not in the 2011 NEI. These data were incorporated into the RTR 
emissions dataset, and include emission data for space heaters, boilers 
and underground fuel tanks at the facilities. Although the 2005 NATA 
data is outdated, we thought it important to ensure we had accounted 
for all the major sources in the source category and given that we did 
not have data on three of the facilities, EPA augmented our RTR 
emissions dataset with this data for three of the 144 facilities. We 
expect to have updated NATA soon and will consider the impact on the 
three sources, as appropriate. NATA is the EPA's ongoing evaluation of 
air toxics in the United States. The EPA developed NATA as a screening 
tool for state/local/tribal agencies to prioritize pollutants, emission 
sources and locations of interest for further study in order to gain a 
better understanding of population risks. NATA assessments do not 
incorporate refined information about emission sources, but rather use 
general information about sources to develop estimates of risks which 
are more likely to overestimate impacts than underestimate them. NATA 
provides estimates of the risk of cancer and other serious health 
effects from breathing (inhaling) air toxics in order to inform both 
national and more localized efforts to identify and prioritize air 
toxics, emission source types and locations which are of greatest 
potential concern in terms of contributing to population risk.

E. What litigation is related to this proposed action?

    In 2007, the United States Court of Appeals for the District of 
Columbia Circuit found that the EPA had erred in establishing emissions 
standards for sources of HAP in the NESHAP for Brick and Structural 
Clay Products Manufacturing and Clay Ceramics Manufacturing, 67 FR 
26690 (May 16, 2003), and consequently vacated the rules.\3\ Among 
other things, the court found EPA erred by failing to regulate 
processes that emitted HAP, in some instances by establishing a MACT 
floor of ``no control.'' In this action we are proposing to correct the 
same error in the Aerospace NESHAP by proposing to remove the exemption 
for specialty coatings found at 40 CFR 63.741(f) and instead add limits 
for specialty coatings (including adhesives, adhesive bonding primers 
and sealants).
---------------------------------------------------------------------------

    \3\ Sierra Club v. EPA, 479 F. 3d 875 (D.C. Cir. March 13, 
2007).
---------------------------------------------------------------------------

    In a separate case, the court vacated portions of two provisions in 
the EPA's CAA section 112 regulations that govern emissions of HAP 
during periods of SSM.\4\ Specifically, the court vacated the SSM 
exemption contained in 40 CFR 63.6(f)(1) and 40 CFR 63.6(h)(1), holding 
that under section 302(k) of the CAA, emissions standards or 
limitations must be continuous in nature and that the SSM exemption 
violates the CAA's requirement that some section 112 standards apply 
continuously. In this action, we are also proposing to revise these 
provisions for Aerospace Manufacturing and Rework Facilities 
operations, as discussed in section IV.E.2 of this preamble.
---------------------------------------------------------------------------

    \4\ Sierra Club v. EPA, 551 F. 3d 1019 (D.C. Cir. 2008), cert. 
denied, 130 S. Ct 1735 (2010).
---------------------------------------------------------------------------

III. Analytical Procedures

    In this section, we describe the analyses performed to support the 
proposed decisions for the RTR and other issues addressed in this 
proposal.

A. How did we estimate post-MACT risks posed by the source category?

    The EPA conducted a risk assessment that provides estimates of the 
MIR posed by the HAP emissions from each source in the source category, 
the hazard index (HI) for chronic exposures to HAP with the potential 
to cause non-cancer health effects and the hazard quotient (HQ) for 
acute exposures to HAP with the potential to cause non-cancer health 
effects. The assessment also provides estimates of the distribution of 
cancer risks within the exposed populations, cancer incidence and an 
evaluation of the potential for adverse environmental effects. The 
seven sections that follow this paragraph describe how we estimated 
emissions and conducted the risk assessment. The docket for this 
rulemaking contains the following document that provides more 
information on the risk assessment inputs and models: Residual Risk 
Assessment for the Aerospace Manufacturing and Rework Facilities Source 
Category in Support of the January, 2015 Risk and Technology Review 
Proposal, January 2015. The methods used to assess risks (as described 
in the primary steps below) are consistent with those peer-reviewed by 
a panel of the EPA's Science Advisory Board (SAB) in 2009 and described 
in their peer review report issued in 2010;\5\ they are also consistent 
with the key recommendations contained in that report.
---------------------------------------------------------------------------

    \5\ U.S. EPA SAB. Risk and Technology Review (RTR) Risk 
Assessment Methodologies: For Review by the EPA's Science Advisory 
Board with Case Studies--MACT I Petroleum Refining Sources and 
Portland Cement Manufacturing, May 2010.
---------------------------------------------------------------------------

1. How did we estimate actual emissions and identify the emissions 
release characteristics?
    Data for 144 Aerospace Manufacturing and Rework Facilities were 
used to create the RTR emissions dataset, as described in section II.C 
of this preamble. The emissions sources included in the RTR emissions 
dataset includes the following types of sources currently regulated by 
the Aerospace NESHAP: Primer/topcoat application operations, waste 
handling operations, chemical milling maskant application

[[Page 8400]]

operations, cleaning operations and chemical and blast depainting 
operations. The RTR emissions dataset also includes the following types 
of sources not currently regulated by the Aerospace NESHAP: Specialty 
coatings, composite processing, chemical milling and metal finishing, 
wastewater, storage tanks, boilers, engines, chemical manufacturing 
processes, secondary metal production processes, heaters, soil 
remediation, transportation equipment, waste disposal, welding and 
other miscellaneous manufacturing processes. These emission sources 
include both fugitive emissions and stack emissions. This RTR emissions 
dataset is based primarily on data gathered through the CAA section 114 
questionnaire, as described in section II.C of this preamble. This 
dataset was supplemented with data received from the 2012 ICR for stack 
testing data and the 2013 request for information on coatings analyses 
(as described in section II.C of this preamble), the 2011 NEI (as 
described in section II.D of this preamble) and the 2005 NATA (as 
described in section II.D of this preamble). The sources noted above 
provided all of the emissions data in the RTR emissions dataset and 
nearly all of the facility specific data needed to conduct the risk 
modeling analysis. However, there were limited instances where default 
values were used to fill gaps in the facility-specific data used in the 
risk modeling analysis. Examples of default values used to fill these 
data gaps were default values used for stack height and other release 
point parameters, and percentages used to segregate mercury and 
chromium compounds into separate species. Use of defaults is discussed 
in detail in the memorandum, Aerospace Manufacturing and Rework 
Facilities RTR Modeling File Preparation, December 2014, available in 
the docket for this action (Modeling File Preparation Memo).
    The RTR emissions dataset was refined following an extensive 
quality assurance check of source locations, emission release 
characteristics and annual emission estimates. We checked the 
coordinates of each emission source in the dataset using ArcGIS to 
ensure the emission point locations were correct. Also, as discussed in 
section II.C of this preamble, in May 2014, the EPA solicited industry 
review of the dataset and made corrections, as needed. For further 
information on the EPA's quality assurance review, see the Modeling 
File Preparation Memo available in the docket for this action.
    A list of the 144 facilities and additional information used to 
develop the RTR emissions dataset is available in the Aerospace RTR 
database, and documentation on the development of this database is 
provided in the Modeling File Preparation Memo, both of which are 
available in the docket for this action.
2. How did we estimate MACT-allowable emissions?
    The available emissions data in the RTR emissions dataset include 
estimates of the actual mass of HAP emitted during the specified annual 
time period. In some cases, these ``actual'' emission levels are lower 
than the emission levels required to comply with the MACT standards. 
The emissions level allowed to be emitted by the MACT standards is 
referred to as the ``MACT-allowable'' emissions level. We discussed the 
use of both MACT-allowable and actual emissions in the final Coke Oven 
Batteries residual risk rule (70 FR 19998-19999, April 15, 2005) and in 
the proposed and final Hazardous Organic NESHAP residual risk rules (71 
FR 34428, June 14, 2006 and 71 FR 76609, December 21, 2006, 
respectively). In those previous actions, we noted that assessing the 
risks at the MACT-allowable level is inherently reasonable since these 
risks reflect the maximum level facilities could emit and still comply 
with national emission standards. We also explained that it is 
reasonable to consider actual emissions, where such data are available, 
in both steps of the risk analysis, in accordance with the Benzene 
NESHAP approach. (54 FR 38044, September 14, 1989.)
    We used the RTR emissions dataset discussed in section III.A.1 of 
this preamble to estimate MACT-allowable emissions levels. Facilities 
were asked to provide a multiplier in the 2011 ICR survey to scale up 
average hourly emissions to maximum hourly emissions for air dispersion 
modeling, given that each facility typically has a large number of 
emission points and it would be difficult to determine the maximum 
hourly emissions from each emission point. Many of the facilities 
reported multipliers that were based on, for example, scaling 
production from 2,000 hours to 8,760 hours per year or from one shift 
per day to three shifts. However, using these values would have led to 
unrealistically high ``allowable'' emission values because of 
limitations in the market for new aerospace vehicles and for rework 
services, and because many facilities have permit restrictions on their 
total annual emissions. Therefore, the EPA did not use maximum hourly 
emissions and instead chose to use a multiplier based on current and 
historical industry capacity utilization factors. The EPA chose to use 
a single multiplier of 1.02 to scale average annual emissions to 
allowable annual emissions. The allowable emissions multiplier is based 
on the difference between 2008 production utilization rate of 83.1 
percent and the 20-year historical maximum production utilization rate 
from 1990 of 85.0 percent (85 / 83.1 = 1.02). The docket for this 
rulemaking contains information on the development of estimated MACT-
allowable emissions in the Modeling File Preparation Memo.
3. How did we conduct dispersion modeling, determine inhalation 
exposures and estimate individual and population inhalation risks?
    Both long-term and short-term inhalation exposure concentrations 
and health risks from the source category addressed in this proposal 
were estimated using the Human Exposure Model (Community and Sector 
HEM-3 version 1.1.0). The HEM-3 performs three primary risk assessment 
activities: (1) Conducting dispersion modeling to estimate the 
concentrations of HAP in ambient air, (2) estimating long-term and 
short-term inhalation exposures to individuals residing within 50 
kilometers (km) of the modeled sources \6\ and (3) estimating 
individual and population-level inhalation risks using the exposure 
estimates and quantitative dose-response information.
---------------------------------------------------------------------------

    \6\ This metric comes from the Benzene NESHAP. See 54 FR 38046.
---------------------------------------------------------------------------

    The air dispersion model used in the analysis, the AERMOD model, is 
one of the EPA's preferred models for assessing pollutant 
concentrations from industrial facilities.\7\ To perform the dispersion 
modeling and to develop the preliminary risk estimates, HEM-3 draws on 
three data libraries. The first is a library of meteorological data, 
which is used for dispersion calculations. This library includes 1 year 
(2011) of hourly surface and upper air observations for more than 800 
meteorological stations, selected to provide coverage of the United 
States and Puerto Rico. A second library of United States Census Bureau 
census block \8\ internal point locations and populations provides the 
basis of human exposure calculations (U.S. Census, 2010). In addition, 
for each census block, the census library

[[Page 8401]]

includes the elevation and controlling hill height, which are also used 
in dispersion calculations. A third library of pollutant unit risk 
factors and other health benchmarks is used to estimate health risks. 
These risk factors and health benchmarks are the latest values 
recommended by the EPA for HAP and other toxic air pollutants. These 
values are available at: https://www.epa.gov/ttn/atw/toxsource/summary.html and are discussed in more detail later in this section.
---------------------------------------------------------------------------

    \7\ U.S. EPA. Revision to the Guideline on Air Quality Models: 
Adoption of a Preferred General Purpose (Flat and Complex Terrain) 
Dispersion Model and Other Revisions (70 FR 68218, November 9, 
2005).
    \8\ A census block is the smallest geographic area for which 
census statistics are tabulated.
---------------------------------------------------------------------------

    In developing the risk assessment for chronic exposures, we used 
the estimated annual average ambient air concentrations of each HAP 
emitted by each source for which we have emissions data in the source 
category. The air concentrations at each nearby census block centroid 
were used as a surrogate for the chronic inhalation exposure 
concentration for all the people who reside in that census block. We 
calculated the MIR for each facility as the cancer risk associated with 
a continuous lifetime (24 hours per day, 7 days per week and 52 weeks 
per year for a 70-year period) exposure to the maximum concentration at 
the centroid of inhabited census blocks. Individual cancer risks were 
calculated by multiplying the estimated lifetime exposure to the 
ambient concentration of each of the HAP (in micrograms per cubic meter 
([mu]g/m\3\)) by its unit risk estimate (URE). The URE is an upper 
bound estimate of an individual's probability of contracting cancer 
over a lifetime of exposure to a concentration of 1 microgram of the 
pollutant per cubic meter of air. For residual risk assessments, we 
generally use URE values from the EPA's Integrated Risk Information 
System (IRIS). For carcinogenic pollutants without IRIS values, we look 
to other reputable sources of cancer dose-response values, often using 
California EPA (CalEPA) URE values, where available. In cases where 
new, scientifically credible dose response values have been developed 
in a manner consistent with the EPA guidelines and have undergone a 
peer review process similar to that used by the EPA, we may use such 
dose-response values in place of, or in addition to, other values, if 
appropriate.
    The EPA estimated incremental individual lifetime cancer risks 
associated with emissions from the facilities in the source category as 
the sum of the risks for each of the carcinogenic HAP (including those 
classified as carcinogenic to humans, likely to be carcinogenic to 
humans and suggestive evidence of carcinogenic potential \9\) emitted 
by the modeled sources. Cancer incidence and the distribution of 
individual cancer risks for the population within 50 km of the sources 
were also estimated for the source category as part of this assessment 
by summing individual risks. A distance of 50 km is consistent with 
both the analysis supporting the 1989 Benzene NESHAP (54 FR 38044, 
September 14, 1989) and the limitations of Gaussian dispersion models, 
including AERMOD.
---------------------------------------------------------------------------

    \9\ These classifications also coincide with the terms ``known 
carcinogen, probable carcinogen, and possible carcinogen,'' 
respectively, which are the terms advocated in the EPA's previous 
Guidelines for Carcinogen Risk Assessment, published in 1986 (51 FR 
33992, September 24, 1986). Summing the risks of these individual 
compounds to obtain the cumulative cancer risks is an approach that 
was recommended by the EPA's SAB in their 2002 peer review of EPA's 
NATA entitled, NATA--Evaluating the National-scale Air Toxics 
Assessment 1996 Data--an SAB Advisory, available at: https://
yosemite.epa.gov/sab/sabproduct.nsf/
214C6E915BB04E14852570CA007A682C/$File/ecadv02001.pdf.
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    To assess the risk of non-cancer health effects from chronic 
exposures, we summed the HQ for each of the HAP that affects a common 
target organ system to obtain the HI for that target organ system (or 
target organ-specific HI, TOSHI). The HQ is the estimated exposure 
divided by the chronic reference value, which is a value selected from 
one of several sources. First, the chronic reference level can be the 
EPA reference concentration (RfC) (https://www.epa.gov/riskassessment/glossary.htm), defined as ``an estimate (with uncertainty spanning 
perhaps an order of magnitude) of a continuous inhalation exposure to 
the human population (including sensitive subgroups) that is likely to 
be without an appreciable risk of deleterious effects during a 
lifetime.'' Alternatively, in cases where an RfC from the EPA's IRIS 
database is not available or where the EPA determines that using a 
value other than the RfC is appropriate, the chronic reference level 
can be a value from the following prioritized sources: (1) The Agency 
for Toxic Substances and Disease Registry (ATSDR) Minimum Risk Level 
(https://www.atsdr.cdc.gov/mrls/index.asp), which is defined as ``an 
estimate of daily human exposure to a hazardous substance that is 
likely to be without an appreciable risk of adverse non-cancer health 
effects (other than cancer) over a specified duration of exposure''; 
(2) the CalEPA Chronic Reference Exposure Level (REL) (https://www.oehha.ca.gov/air/hot_spots/pdf/HRAguidefinal.pdf), which is defined 
as ``the concentration level (that is expressed in units of micrograms 
per cubic meter ([mu]g/m\3\) for inhalation exposure and in a dose 
expressed in units of milligram per kilogram-day for oral exposures), 
at or below which no adverse health effects are anticipated for a 
specified exposure duration''; or (3), as noted above, a scientifically 
credible dose-response value that has been developed in a manner 
consistent with the EPA guidelines and has undergone a peer review 
process similar to that used by the EPA, in place of or in concert with 
other values.
    As mentioned above, in order to characterize non-cancer chronic 
effects, and in response to key recommendations from the SAB, the EPA 
selects dose-response values that reflect the best available science 
for all HAP included in RTR risk assessments.\10\ More specifically, 
for a given HAP, the EPA examines the availability of inhalation 
reference values from the sources included in our tiered approach 
(e.g., IRIS first, ATSDR second, CalEPA third) and determines which 
inhalation reference value represents the best available science. Thus, 
as new inhalation reference values become available, the EPA will 
typically evaluate them and determine whether they should be given 
preference over those currently being used in RTR risk assessments.
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    \10\ The SAB peer review of RTR Risk Assessment Methodologies is 
available at: https://yosemite.epa.gov/sab/sabproduct.nsf/
4AB3966E263D943A8525771F00668381/$File/EPA-SAB-10-007-unsigned.pdf.
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    The EPA also evaluated screening estimates of acute exposures and 
risks for each of the HAP at the point of highest potential off-site 
exposure for each facility. To do this, the EPA estimated the risks 
when both the peak hourly emissions rate and worst-case dispersion 
conditions occur. We also assume that a person is located at the point 
of highest impact during that same time. In accordance with our mandate 
in section 112 of the CAA, we use the point of highest off-site 
exposure to assess the potential risk to the maximally exposed 
individual. The acute HQ is the estimated acute exposure divided by the 
acute dose-response value. In each case, the EPA calculated acute HQ 
values using best available, short-term dose-response values. These 
acute dose-response values, which are described below, include the 
acute REL, acute exposure guideline levels (AEGL) and emergency 
response planning guidelines (ERPG) for 1-hour exposure durations. As 
discussed below, we used conservative assumptions for emissions rates, 
meteorology and exposure location for our acute analysis.

[[Page 8402]]

    As described in the CalEPA's Air Toxics Hot Spots Program Risk 
Assessment Guidelines, Part I, The Determination of Acute Reference 
Exposure Levels for Airborne Toxicants, an acute REL value (https://www.oehha.ca.gov/air/pdf/acuterel.pdf) is defined as ``the 
concentration level at or below which no adverse health effects are 
anticipated for a specified exposure duration.'' Id. at page 2. Acute 
REL values are based on the most sensitive, relevant, adverse health 
effect reported in the peer-reviewed medical and toxicological 
literature. Acute REL values are designed to protect the most sensitive 
individuals in the population through the inclusion of margins of 
safety. Because margins of safety are incorporated to address data gaps 
and uncertainties, exceeding the REL does not automatically indicate an 
adverse health impact.
    AEGL values were derived in response to recommendations from the 
National Research Council (NRC). As described in Standing Operating 
Procedures (SOP) of the National Advisory Committee on Acute Exposure 
Guideline Levels for Hazardous Substances (https://www.epa.gov/oppt/aegl/pubs/sop.pdf),\11\ ``the NRC's previous name for acute exposure 
levels--community emergency exposure levels--was replaced by the term 
AEGL to reflect the broad application of these values to planning, 
response and prevention in the community, the workplace, 
transportation, the military and the remediation of Superfund sites.'' 
Id. at 2. This document also states that AEGL values ``represent 
threshold exposure limits for the general public and are applicable to 
emergency exposures ranging from 10 minutes to eight hours.'' Id. at 2.
---------------------------------------------------------------------------

    \11\ National Academy of Sciences (NAS), 2001. Standing 
Operating Procedures for Developing Acute Exposure Levels for 
Hazardous Chemicals, page 2.
---------------------------------------------------------------------------

    The document lays out the purpose and objectives of AEGL by stating 
that ``the primary purpose of the AEGL program and the National 
Advisory Committee for Acute Exposure Guideline Levels for Hazardous 
Substances is to develop guideline levels for once-in-a-lifetime, 
short-term exposures to airborne concentrations of acutely toxic, high-
priority chemicals.'' Id. at 21. In detailing the intended application 
of AEGL values, the document states that ``[i]t is anticipated that the 
AEGL values will be used for regulatory and nonregulatory purposes by 
U.S. federal and state agencies and possibly the international 
community in conjunction with chemical emergency response, planning and 
prevention programs. More specifically, the AEGL values will be used 
for conducting various risk assessments to aid in the development of 
emergency preparedness and prevention plans, as well as real-time 
emergency response actions, for accidental chemical releases at fixed 
facilities and from transport carriers.'' Id. at 31.
    The AEGL-1 value is then specifically defined as ``the airborne 
concentration (expressed as ppm (parts per million) or mg/m\3\ 
(milligrams per cubic meter)) of a substance above which it is 
predicted that the general population, including susceptible 
individuals, could experience notable discomfort, irritation, or 
certain asymptomatic nonsensory effects. However, the effects are not 
disabling and are transient and reversible upon cessation of 
exposure.'' Id. at 3. The document also notes that, ``Airborne 
concentrations below AEGL-1 represent exposure levels that can produce 
mild and progressively increasing but transient and nondisabling odor, 
taste, and sensory irritation or certain asymptomatic, nonsensory 
effects.'' Id. Similarly, the document defines AEGL-2 values as ``the 
airborne concentration (expressed as parts per million or milligrams 
per cubic meter) of a substance above which it is predicted that the 
general population, including susceptible individuals, could experience 
irreversible or other serious, long-lasting adverse health effects or 
an impaired ability to escape.'' Id.
    ERPG values are derived for use in emergency response, as described 
in the American Industrial Hygiene Association's Emergency Response 
Planning Committee document titled, ERPGS Procedures and 
Responsibilities (https://sp4m.aiha.org/insideaiha/GuidelineDevelopment/ERPG/Documents/ERP-SOPs2006.pdf), which states that, ``Emergency 
Response Planning Guidelines were developed for emergency planning and 
are intended as health based guideline concentrations for single 
exposures to chemicals.'' \12\ Id. at 1. The ERPG-1 value is defined as 
``the maximum airborne concentration below which it is believed that 
nearly all individuals could be exposed for up to 1 hour without 
experiencing other than mild transient adverse health effects or 
without perceiving a clearly defined, objectionable odor.'' Id. at 2. 
Similarly, the ERPG-2 value is defined as ``the maximum airborne 
concentration below which it is believed that nearly all individuals 
could be exposed for up to one hour without experiencing or developing 
irreversible or other serious health effects or symptoms which could 
impair an individual's ability to take protective action.'' Id. at 1.
---------------------------------------------------------------------------

    \12\ ERP Committee Procedures and Responsibilities. November 1, 
2006. American Industrial Hygiene Association.
---------------------------------------------------------------------------

    As can be seen from the definitions above, the AEGL and ERPG values 
include the similarly defined severity levels 1 and 2. For many 
chemicals, a severity level 1 value AEGL or ERPG has not been developed 
because the types of effects for these chemicals are not consistent 
with the AEGL-1/ERPG-1 definitions; in these instances, we compare 
higher severity level AEGL-2 or ERPG-2 values to our modeled exposure 
levels to screen for potential acute concerns. When AEGL-1/ERPG-1 
values are available, they are used in our acute risk assessments.
    Acute REL values for 1-hour exposure durations are typically lower 
than their corresponding AEGL-1 and ERPG-1 values. Even though their 
definitions are slightly different, AEGL-1 values are often the same as 
the corresponding ERPG-1 values, and AEGL-2 values are often equal to 
ERPG-2 values. Maximum HQ values from our acute screening risk 
assessments typically result when basing them on the acute REL value 
for a particular pollutant. In cases where our maximum acute HQ value 
exceeds 1, we also report the HQ value based on the next highest acute 
dose-response value (usually the AEGL-1 and/or the ERPG-1 value).
    To develop screening estimates of acute exposures in the absence of 
hourly emissions data, generally we first develop estimates of maximum 
hourly emissions rates by multiplying the average actual annual hourly 
emissions rates by a default factor to cover routinely variable 
emissions. We choose the factor to use partially based on process 
knowledge and engineering judgment. The factor chosen also reflects a 
Texas study of short-term emissions variability, which showed that most 
peak emission events in a heavily-industrialized four-county area 
(Harris, Galveston, Chambers and Brazoria Counties, Texas) were less 
than twice the annual average hourly emissions rate. The highest peak 
emissions event was 74 times the annual average hourly emissions rate, 
and the 99th percentile ratio of peak hourly emissions rate to the 
annual average hourly emissions rate was 9.\13\ Considering this 
analysis, to account for more than 99 percent of the peak hourly

[[Page 8403]]

emissions, we apply a conservative screening multiplication factor of 
10 to the average annual hourly emissions rate in our acute exposure 
screening assessments as our default approach. However, we use a factor 
other than 10 if we have information that indicates that a different 
factor is appropriate for a particular source category.
---------------------------------------------------------------------------

    \13\ See https://www.tceq.state.tx.us/compliance/field_ops/eer/ or the docket to access the source of these data.
---------------------------------------------------------------------------

    For this source category, the default value was not utilized. A 
peak 1-hour emission multiplier of 1.2 times the annual emissions was 
utilized for the entire source category. This value was developed from 
current and historical industry capacity utilization factors. The 
emissions from this category are generally dependent on the amount of 
HAP in the coatings and the amount of coating applied, and would only 
vary in a significant manner if production increased. Therefore, the 
EPA based the acute emissions multiplier on potential changes in 
production. The acute emissions multiplier is based on the difference 
between 2008 production utilization rate of 83.1 percent and the 
maximum production utilization rate of 100 percent, which has not been 
realized in 20 years of historical data (100 / 83.1 = 1.2). The docket 
for this rulemaking contains information on the development of 
estimated MACT-acute emissions in the Modeling File Preparation Memo. A 
further discussion of why this factor was chosen can be found in 
Appendix 1 of the Modeling File Preparation Memo, available in the 
docket for this rulemaking.
    As part of our acute risk assessment process, for cases where acute 
HQ values from the screening step were less than or equal to 1 (even 
under the conservative assumptions of the screening analysis), acute 
impacts were deemed negligible and no further analysis was performed. 
In cases where an acute HQ from the screening step was greater than 1, 
additional site-specific data were considered to develop a more refined 
estimate of the potential for acute impacts of concern. For this source 
category, the data refinements employed consisted of evaluating the 
off-site extent of any exceedances of the acute health benchmarks. 
These refinements are discussed more fully in the Modeling File 
Preparation Memo, which is available in the docket for this source 
category. Ideally, we would prefer to have continuous measurements over 
time to see how the emissions vary by each hour over an entire year. 
Having a frequency distribution of hourly emissions rates over a year 
would allow us to perform a probabilistic analysis to estimate 
potential threshold exceedances and their frequency of occurrence. Such 
an evaluation could include a more complete statistical treatment of 
the key parameters and elements adopted in this screening analysis. 
Recognizing that this level of data is rarely available, we instead 
rely on the multiplier approach.
    To better characterize the potential health risks associated with 
estimated acute exposures to HAP, and in response to a key 
recommendation from the SAB's peer review of the EPA's RTR risk 
assessment methodologies,\14\ we generally examine a wider range of 
available acute health metrics (e.g., RELs, AEGLs) than we do for our 
chronic risk assessments. This is in response to the SAB's 
acknowledgement that there are generally more data gaps and 
inconsistencies in acute reference values than there are in chronic 
reference values. In some cases, when Reference Value Arrays \15\ for 
HAP have been developed, we consider additional acute values (i.e., 
occupational and international values) to provide a more complete risk 
characterization.
---------------------------------------------------------------------------

    \14\ The SAB peer review of RTR Risk Assessment Methodologies is 
available at: https://yosemite.epa.gov/sab/sabproduct.nsf/
4AB3966E263D943A8525771F00668381/$File/EPA-SAB-10-007-unsigned.pdf.
    \15\ U.S. EPA. (2009) Chapter 2.9, Chemical Specific Reference 
Values for Formaldehyde, in Graphical Arrays of Chemical-Specific 
Health Effect Reference Values for Inhalation Exposures (Final 
Report). U.S. Environmental Protection Agency, Washington, DC, EPA/
600/R-09/061, and available online at https://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=211003.
---------------------------------------------------------------------------

4. How did we conduct the multipathway exposure and risk screening?
    The EPA conducted a screening analysis examining the potential for 
significant human health risks due to exposures via routes other than 
inhalation (i.e., ingestion). We first determined whether any sources 
in the Aerospace Manufacturing and Rework Facilities source category 
emitted any HAP known to be persistent and bioaccumulative in the 
environment (PB-HAP). The PB-HAP compounds or compound classes are 
identified for the screening from the EPA's Air Toxics Risk Assessment 
Library (available at https://www2.epa.gov/fera/risk-assessment-and-modeling-air-toxics-risk-assessment-reference-library).
    For the Aerospace Manufacturing and Rework Facilities source 
category, we identified emissions of cadmium, dioxins/furans, POM, 
mercury (both inorganic mercury and methyl mercury) and lead compounds. 
Because one or more of these PB-HAP are emitted by at least one 
facility in the Aerospace Manufacturing and Rework Facilities source 
category, we proceeded to the next step of the evaluation. In this 
step, we determined whether the facility-specific emissions rates of 
the emitted PB-HAP were large enough to create the potential for 
significant non-inhalation human health risks under reasonable worst-
case conditions. To facilitate this step, we developed emissions rate 
screening levels for several PB-HAP using a hypothetical upper-end 
screening exposure scenario developed for use in conjunction with the 
EPA's Total Risk Integrated Methodology.Fate, Transport, and Ecological 
Exposure (TRIM.FaTE) model. The PB-HAP with emissions rate screening 
levels are: Lead, cadmium, chlorinated dibenzodioxins and furans, 
mercury compounds and POM. We conducted a sensitivity analysis on the 
screening scenario to ensure that its key design parameters would 
represent the upper end of the range of possible values, such that it 
would represent a conservative, but not impossible scenario. The 
facility-specific emissions rates of these PB-HAP were compared to the 
emission rate screening levels for these PB-HAP to assess the potential 
for significant human health risks via non-inhalation pathways. We call 
this application of the TRIM.FaTE model the Tier 1 TRIM-screen or Tier 
1 screen.
    For the purpose of developing emissions rates for our Tier 1 TRIM-
screen, we derived emission levels for these PB-HAP (other than lead 
compounds) at which the maximum excess lifetime cancer risk would be 1-
in-1 million (i.e., for polychlorinated dibenzodioxins and furans and 
POM) or, for HAP that cause non-cancer health effects (i.e., cadmium 
compounds and mercury compounds), the maximum HQ would be 1. If the 
emissions rate of any PB-HAP included in the Tier 1 screen exceeds the 
Tier 1 screening emissions rate for any facility, we conduct a second 
screen, which we call the Tier 2 TRIM-screen or Tier 2 screen.
    In the Tier 2 screen, the location of each facility that exceeded 
the Tier 1 emission rate is used to refine the assumptions associated 
with the environmental scenario while maintaining the exposure scenario 
assumptions. A key assumption that is part of the Tier 1 screen is that 
a lake is located near the facility; we confirm the existence of lakes 
near the facility as part of the Tier 2 screen. We then adjust the 
risk-based Tier 1 screening level for each PB-HAP for each facility 
based on an understanding of how exposure concentrations estimated for 
the screening scenario change with meteorology and environmental 
assumptions. PB-HAP emissions that do

[[Page 8404]]

not exceed these new Tier 2 screening levels are considered to pose no 
unacceptable risks. If the PB-HAP emissions for a facility exceed the 
Tier 2 screening emissions rate and data are available, we may decide 
to conduct a more refined Tier 3 multipathway assessment. There are 
several analyses that can be included in a Tier 3 screen depending upon 
the extent of refinement warranted, including validating that the lake 
is fishable and considering plume-rise to estimate emissions lost above 
the mixing layer. If the Tier 3 screen is exceeded, the EPA may further 
refine the assessment.
    In evaluating the potential multipathway risk from emissions of 
lead compounds, rather than developing a screening emissions rate for 
them, we compared maximum estimated chronic inhalation exposures with 
the level of the current National Ambient Air Quality Standard (NAAQS) 
for lead.\16\ Values below the level of the primary (health-based) lead 
NAAQS were considered to have a low potential for multipathway risk.
---------------------------------------------------------------------------

    \16\ In doing so, EPA notes that the legal standard for a 
primary NAAQS--that a standard is requisite to protect public health 
and provide an adequate margin of safety (CAA section 109(b))--
differs from the CAA section 112(f) standard (requiring among other 
things that the standard provide an ``ample margin of safety''). 
However, the lead NAAQS is a reasonable measure of determining risk 
acceptability (i.e., the first step of the Benzene NESHAP analysis) 
since it is designed to protect the most susceptible group in the 
human population--children, including children living near major 
lead emitting sources (73 FR 67002/3; 73 FR 67000/3; 73 FR 67005/1). 
In addition, applying the level of the primary lead NAAQS at the 
risk acceptability step is conservative, since that primary lead 
NAAQS reflects an adequate margin of safety.
---------------------------------------------------------------------------

    For further information on the multipathway analysis approach, see 
the Residual Risk Assessment for the Aerospace Manufacturing and Rework 
Facilities Source Category in Support of the January, 2015 Risk and 
Technology Review Proposal, January 2015, which is available in the 
docket for this action.
5. How did we conduct the environmental risk screening assessment?
a. Adverse Environmental Effect
    The EPA conducts a screening assessment to examine the potential 
for adverse environmental effects as required under section 
112(f)(2)(A) of the CAA. Section 112(a)(7) of the CAA defines ``adverse 
environmental effect'' as ``any significant and widespread adverse 
effect, which may reasonably be anticipated, to wildlife, aquatic life 
or other natural resources, including adverse impacts on populations of 
endangered or threatened species or significant degradation of 
environmental quality over broad areas.''
b. Environmental HAP
    The EPA focuses on seven HAP, which we refer to as ``environmental 
HAP,'' in its screening analysis: Five PB-HAP and two acid gases. The 
five PB-HAP are cadmium, dioxins/furans, POM, mercury (both inorganic 
mercury and methyl mercury) and lead compounds. The two acid gases are 
hydrogen chloride (HCl) and hydrogen fluoride (HF). The rationale for 
including these seven HAP in the environmental risk screening analysis 
is presented below.
    HAP that persist and bioaccumulate are of particular environmental 
concern because they accumulate in the soil, sediment and water. The 
PB-HAP are taken up, through sediment, soil, water and/or ingestion of 
other organisms, by plants or animals (e.g., small fish) at the bottom 
of the food chain. As larger and larger predators consume these 
organisms, concentrations of the PB-HAP in the animal tissues increases 
as does the potential for adverse effects. The five PB-HAP we evaluate 
as part of our screening analysis account for 99.8 percent of all PB-
HAP emissions nationally from stationary sources (on a mass basis from 
the 2005 NEI).
    In addition to accounting for almost all of the mass of PB-HAP 
emitted, we note that the TRIM.FaTE model that we use to evaluate 
multipathway risk allows us to estimate concentrations of cadmium 
compounds, dioxins/furans, POM and mercury in soil, sediment and water. 
For lead compounds, we currently do not have the ability to calculate 
these concentrations using the TRIM.FaTE model. Therefore, to evaluate 
the potential for adverse environmental effects from lead compounds, we 
compare the estimated HEM-modeled exposures from the source category 
emissions of lead with the level of the secondary NAAQS for lead.\17\ 
We consider values below the level of the secondary NAAQS for lead to 
be unlikely to cause adverse environmental effects.
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    \17\ The secondary NAAQS for lead is a reasonable measure of 
determining whether there is an adverse environmental effect since 
it was established considering ``effects on soils, water, crops, 
vegetation, man-made materials, animals, wildlife, weather, 
visibility and climate, damage to and deterioration of property, and 
hazards to transportation, as well as effects on economic values and 
on personal comfort and well-being.''
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    Due to their well-documented potential to cause direct damage to 
terrestrial plants, we include two acid gases, HCl and HF, in the 
environmental screening analysis. According to the 2005 NEI, HCl and HF 
account for about 99 percent (on a mass basis) of the total acid gas 
HAP emitted by stationary sources in the U.S. In addition to the 
potential to cause direct damage to plants, high concentrations of HF 
in the air have been linked to fluorosis in livestock. Air 
concentrations of these HAP are already calculated as part of the human 
multipathway exposure and risk screening analysis using the HEM3-AERMOD 
air dispersion model, and we are able to use the air dispersion 
modeling results to estimate the potential for an adverse environmental 
effect.
    The EPA acknowledges that other HAP beyond the seven HAP discussed 
above may have the potential to cause adverse environmental effects. 
Therefore, the EPA may include other relevant HAP in its environmental 
risk screening in the future, as modeling science and resources allow. 
The EPA invites comment on the extent to which other HAP emitted by the 
source category may cause adverse environmental effects. Such 
information should include references to peer-reviewed ecological 
effects benchmarks that are of sufficient quality for making regulatory 
decisions, as well as information on the presence of organisms located 
near facilities within the source category that such benchmarks 
indicate could be adversely affected.
c. Ecological Assessment Endpoints and Benchmarks for PB-HAP
    An important consideration in the development of the EPA's 
screening methodology is the selection of ecological assessment 
endpoints and benchmarks. Ecological assessment endpoints are defined 
by the ecological entity (e.g., aquatic communities including fish and 
plankton) and its attributes (e.g., frequency of mortality). Ecological 
assessment endpoints can be established for organisms, populations, 
communities or assemblages and ecosystems.
    For PB-HAP (other than lead compounds), we evaluated the following 
community-level ecological assessment endpoints to screen for organisms 
directly exposed to HAP in soils, sediment and water:
     Local terrestrial communities (i.e., soil invertebrates, 
plants) and populations of small birds and mammals that consume soil 
invertebrates exposed to PB-HAP in the surface soil.
     Local benthic (i.e., bottom sediment dwelling insects, 
amphipods, isopods and crayfish) communities exposed to

[[Page 8405]]

PB-HAP in sediment in nearby water bodies.
     Local aquatic (water-column) communities (including fish 
and plankton) exposed to PB-HAP in nearby surface waters.
    For PB-HAP (other than lead compounds), we also evaluated the 
population-level ecological assessment endpoint to screen for indirect 
HAP exposures of top consumers via the bioaccumulation of HAP in food 
chains. The endpoint evaluated was piscivorous (i.e., fish-eating) 
wildlife consuming PB-HAP-contaminated fish from nearby water bodies.
    For cadmium compounds, dioxins/furans, POM and mercury, we 
identified the available ecological benchmarks for each assessment 
endpoint. An ecological benchmark represents a concentration of HAP 
(e.g., 0.77 [micro]g of HAP per liter of water) that has been linked to 
a particular environmental effect level (e.g., a no-observed-adverse-
effect level (NOAEL)) through scientific study. For PB-HAP, we 
identified, where possible, ecological benchmarks at the following 
effect levels:
     Probable effect levels (PEL): Level above which adverse 
effects are expected to occur frequently.
     Lowest-observed-adverse-effect level (LOAEL): The lowest 
exposure level tested at which there are biologically significant 
increases in frequency or severity of adverse effects.
     No-observed-adverse-effect levels (NOAEL): The highest 
exposure level tested at which there are no biologically significant 
increases in the frequency or severity of adverse effect.
    We established a hierarchy of preferred benchmark sources to allow 
selection of benchmarks for each environmental HAP at each ecological 
assessment endpoint. In general, the EPA sources that are used at a 
programmatic level (e.g., Office of Water, Superfund Program) were 
used, if available. If not, the EPA benchmarks used in regional 
programs (e.g., Superfund) were used. If benchmarks were not available 
at a programmatic or regional level, we used benchmarks developed by 
other federal agencies (e.g., National Oceanic and Atmospheric 
Administration (NOAA)) or state agencies.
    Benchmarks for all effect levels are not available for all PB-HAP 
and assessment endpoints. In cases where multiple effect levels were 
available for a particular PB-HAP and assessment endpoint, we use all 
of the available effect levels to help us to determine whether 
ecological risks exist and, if so, whether the risks could be 
considered significant and widespread.
d. Ecological Assessment Endpoints and Benchmarks for Acid Gases
    The environmental screening analysis also evaluated potential 
damage and reduced productivity of plants due to direct exposure to 
acid gases in the air. For acid gases, we evaluated the ecological 
assessment endpoint of local terrestrial plant communities with foliage 
exposed to acidic gaseous HAP in the air.
    The selection of ecological benchmarks for the effects of acid 
gases on plants followed the same approach as for PB-HAP (i.e., we 
examine all of the available chronic benchmarks). For HCl, the EPA 
identified chronic benchmark concentrations. We note that the benchmark 
for chronic HCl exposure to plants is greater than the reference 
concentration for chronic inhalation exposure for human health. This 
means that where the EPA includes regulatory requirements to prevent an 
exceedance of the reference concentration for human health, additional 
analyses for adverse environmental effects of HCl would not be 
necessary.
    For HF, the EPA identified chronic benchmark concentrations for 
plants and evaluated chronic exposures to plants in the screening 
analysis. High concentrations of HF in the air have also been linked to 
fluorosis in livestock. However, the HF concentrations at which 
fluorosis in livestock occur are higher than those at which plant 
damage begins. Therefore, the benchmarks for plants are protective of 
both plants and livestock.
e. Screening Methodology
    For the environmental risk screening analysis, the EPA first 
determined whether any facilities in the Aerospace Manufacturing and 
Rework Facilities source category emitted any of the seven 
environmental HAP. For the Aerospace Manufacturing and Rework 
Facilities source category, we identified emissions of five PB-HAP and 
two acid gases as the environmental HAP. The five PB-HAP are cadmium, 
dioxins/furans, POM, mercury (both inorganic mercury and methyl 
mercury) and lead compounds. The two acid gases are HCl and HF.
    Because one or more of the seven environmental HAP evaluated are 
emitted by at least one facility in the source category, we proceeded 
to the second step of the evaluation.
f. PB-HAP Methodology
    For cadmium, mercury, POM and dioxins/furans, the environmental 
screening analysis consists of two tiers, while lead compounds are 
analyzed differently as discussed earlier. In the first tier, we 
determined whether the maximum facility-specific emission rates of each 
of the emitted environmental HAP were large enough to create the 
potential for adverse environmental effects under reasonable worst-case 
environmental conditions. These are the same environmental conditions 
used in the human multipathway exposure and risk screening analysis.
    To facilitate this step, TRIM.FaTE was run for each PB-HAP under 
hypothetical environmental conditions designed to provide 
conservatively high HAP concentrations. The model was set to maximize 
runoff from terrestrial parcels into the modeled lake, which in turn, 
maximized the chemical concentrations in the water, the sediments and 
the fish. The resulting media concentrations were then used to back-
calculate a screening level emission rate that corresponded to the 
relevant exposure benchmark concentration value for each assessment 
endpoint. To assess emissions from a facility, the reported emission 
rate for each PB-HAP was compared to the screening level emission rate 
for that PB-HAP for each assessment endpoint. If emissions from a 
facility do not exceed the Tier 1 screening level, the facility 
``passes'' the screen, and, therefore, is not evaluated further under 
the screening approach. If emissions from a facility exceed the Tier 1 
screening level, we evaluate the facility further in Tier 2.
    In Tier 2 of the environmental screening analysis, the emission 
rate screening levels are adjusted to account for local meteorology and 
the actual location of lakes in the vicinity of facilities that did not 
pass the Tier 1 screen. The modeling domain for each facility in the 
Tier 2 analysis consists of eight octants. Each octant contains five 
modeled soil concentrations at various distances from the facility (5 
soil concentrations x 8 octants = total of 40 soil concentrations per 
facility) and one lake with modeled concentrations for water, sediment 
and fish tissue. In the Tier 2 environmental risk screening analysis, 
the 40 soil concentration points are averaged to obtain an average soil 
concentration for each facility for each PB-HAP. For the water, 
sediment and fish tissue concentrations, the highest value for each 
facility for each pollutant is used. If emission concentrations from a 
facility do not exceed the Tier 2 screening level, the facility passes 
the screen, and typically is not evaluated further. If emissions from a 
facility exceed the Tier 2 screening level, the facility does not

[[Page 8406]]

pass the screen and, therefore, may have the potential to cause adverse 
environmental effects. Such facilities are evaluated further to 
investigate factors such as the magnitude and characteristics of the 
area of exceedance.
g. Acid Gas Methodology
    The environmental screening analysis evaluates the potential 
phytotoxicity and reduced productivity of plants due to chronic 
exposure to acid gases. The environmental risk screening methodology 
for acid gases is a single-tier screen that compares the average off-
site ambient air concentration over the modeling domain to ecological 
benchmarks for each of the acid gases. Because air concentrations are 
compared directly to the ecological benchmarks, emission-based 
screening levels are not calculated for acid gases as they are in the 
ecological risk screening methodology for PB-HAP.
    For purposes of ecological risk screening, the EPA identifies a 
potential for adverse environmental effects to plant communities from 
exposure to acid gases when the average concentration of the HAP around 
a facility exceeds the LOAEL ecological benchmark. In such cases, we 
further investigate factors such as the magnitude and characteristics 
of the area of exceedance (e.g., land use of exceedance area, size of 
exceedance area) to determine if there is an adverse environmental 
effect.
    For further information on the environmental screening analysis 
approach, see the Residual Risk Assessment for the Aerospace 
Manufacturing and Rework Facilities Source Category in Support of the 
January, 2015 Risk and Technology Review Proposal, January 2015, which 
is available in the docket for this action.
6. How did we conduct facility-wide assessments?
    To put the source category risks in context, we typically examine 
the risks from the entire ``facility,'' where the facility includes all 
HAP-emitting operations within a contiguous area and under common 
control. In other words, we examine the HAP emissions not only from the 
source category emission points of interest, but also emissions of HAP 
from all other emission sources at the facility for which we have data.
    The emissions inventories developed from the 2011 and 2012 ICRs, 
2011 NEI and 2005 NATA include emissions information for all emissions 
sources at the facilities that are part of the Aerospace Manufacturing 
and Rework Facilities source category. These include sources currently 
regulated by the Aerospace NESHAP: Primer/topcoat application 
operations, waste handling operations, chemical milling maskant 
application operations, cleaning operations and chemical and blast 
depainting operations. These also include emission sources not 
currently regulated by the Aerospace NESHAP: Specialty coatings, 
composite processing, chemical milling and metal finishing, wastewater, 
storage tanks, boilers, engines, chemical manufacturing processes, 
secondary metal production processes, heaters, soil remediation, 
transportation equipment, waste disposal, welding and other 
miscellaneous manufacturing processes.
    We analyzed risks due to the inhalation of HAP that are emitted 
``facility-wide'' for the populations residing within 50 km of each 
facility, consistent with the methods used for the source category 
analysis described above. For these facility-wide risk analyses, the 
modeled source category risks were compared to the facility-wide risks 
to determine the portion of facility-wide risks that could be 
attributed to the source category addressed in this proposal. We 
specifically examined the facility that was associated with the highest 
estimate of risk and determined the percentage of that risk 
attributable to the source category of interest. The Residual Risk 
Assessment for the Aerospace Manufacturing and Rework Facilities Source 
Category in Support of the January, 2015 Risk and Technology Review 
Proposal, January 2015, available through the docket for this action, 
provides the methodology and results of the facility-wide analyses, 
including all facility-wide risks and the percentage of source category 
contribution to facility-wide risks.
7. How did we consider uncertainties in risk assessment?
    In the Benzene NESHAP, we concluded that risk estimation 
uncertainty should be considered in our decision-making under the ample 
margin of safety framework. Uncertainty and the potential for bias are 
inherent in all risk assessments, including those performed for this 
proposal. Although uncertainty exists, we believe that our approach, 
which used conservative tools and assumptions, ensures that our 
decisions are health protective and environmentally protective. A brief 
discussion of the uncertainties in the RTR emissions dataset, 
dispersion modeling, inhalation exposure estimates and dose-response 
relationships follows below. A more thorough discussion of these 
uncertainties is included in the Residual Risk Assessment for the 
Aerospace Manufacturing and Rework Facilities Source Category in 
Support of the January, 2015 Risk and Technology Review Proposal, 
January 2015, which is available in the docket for this action.
a. Uncertainties in the RTR Emissions Dataset
    Although the development of the RTR emissions dataset involved 
quality assurance/quality control processes, the accuracy of emissions 
values will vary depending on the source of the data, the degree to 
which data are incomplete or missing, the degree to which assumptions 
made to complete the datasets are accurate, and errors in emission 
estimates and other factors. The emission estimates considered in this 
analysis are annual totals for certain years, and they do not reflect 
short-term fluctuations during the course of a year or variations from 
year to year. The estimates of peak hourly emission rates for the acute 
effects screening assessment were based on an emission adjustment 
factor applied to the average annual hourly emission rates, which are 
intended to account for emission fluctuations due to normal facility 
operations.
b. Uncertainties in Dispersion Modeling
    We recognize there is uncertainty in ambient concentration 
estimates associated with any model, including the EPA's recommended 
regulatory dispersion model, AERMOD. In using a model to estimate 
ambient pollutant concentrations, the user chooses certain options to 
apply. For RTR assessments, we select some model options that have the 
potential to overestimate ambient air concentrations (e.g., not 
including plume depletion or pollutant transformation). We select other 
model options that have the potential to underestimate ambient impacts 
(e.g., not including building downwash). Other options that we select 
have the potential to either under- or overestimate ambient levels 
(e.g., meteorology and receptor locations). On balance, considering the 
directional nature of the uncertainties commonly present in ambient 
concentrations estimated by dispersion models, the approach we apply in 
the RTR assessments should yield unbiased estimates of ambient HAP 
concentrations.
c. Uncertainties in Inhalation Exposure
    The EPA did not include the effects of human mobility on exposures 
in the assessment. Specifically, short-term mobility and long-term 
mobility between census blocks in the modeling

[[Page 8407]]

domain were not considered.\18\ The approach of not considering short 
or long-term population mobility does not bias the estimate of the 
theoretical MIR (by definition), nor does it affect the estimate of 
cancer incidence because the total population number remains the same. 
It does, however, affect the shape of the distribution of individual 
risks across the affected population, shifting it toward higher 
estimated individual risks at the upper end and reducing the number of 
people estimated to be at lower risks, thereby increasing the estimated 
number of people at specific high risk levels (e.g., 1-in-10 thousand 
or 1-in-1 million).
---------------------------------------------------------------------------

    \18\ Short-term mobility is movement from one micro-environment 
to another over the course of hours or days. Long-term mobility is 
movement from one residence to another over the course of a 
lifetime.
---------------------------------------------------------------------------

    In addition, the assessment predicted the chronic exposures at the 
centroid of each populated census block as surrogates for the exposure 
concentrations for all people living in that block. Using the census 
block centroid to predict chronic exposures tends to over-predict 
exposures for people in the census block who live farther from the 
facility and under-predict exposures for people in the census block who 
live closer to the facility. Thus, using the census block centroid to 
predict chronic exposures may lead to a potential understatement or 
overstatement of the true maximum impact, but is an unbiased estimate 
of average risk and incidence. We reduce this uncertainty by analyzing 
large census blocks near facilities using aerial imagery and adjusting 
the location of the block centroid to better represent the population 
in the block, as well as adding additional receptor locations where the 
block population is not well represented by a single location.
    The assessment evaluates the cancer inhalation risks associated 
with pollutant exposures over a 70-year period, which is the assumed 
lifetime of an individual. In reality, both the length of time that 
modeled emission sources at facilities actually operate (i.e., more or 
less than 70 years) and the domestic growth or decline of the modeled 
industry (i.e., the increase or decrease in the number or size of 
domestic facilities) will influence the future risks posed by a given 
source or source category. Depending on the characteristics of the 
industry, these factors will, in most cases, result in an overestimate 
both in individual risk levels and in the total estimated number of 
cancer cases. However, in the unlikely scenario where a facility 
maintains, or even increases, its emissions levels over a period of 
more than 70 years, residents live beyond 70 years at the same 
location, and the residents spend most of their days at that location, 
then the cancer inhalation risks could potentially be underestimated. 
However, annual cancer incidence estimates from exposures to emissions 
from these sources would not be affected by the length of time an 
emissions source operates.
    The exposure estimates used in these analyses assume chronic 
exposures to ambient (outdoor) levels of pollutants. Because most 
people spend the majority of their time indoors, actual exposures may 
not be as high, depending on the characteristics of the pollutants 
modeled. For many of the HAP, indoor levels are roughly equivalent to 
ambient levels, but for very reactive pollutants or larger particles, 
indoor levels are typically lower. This factor has the potential to 
result in an overestimate of 25 to 30 percent of exposures.\19\
---------------------------------------------------------------------------

    \19\ U.S. EPA. National-Scale Air Toxics Assessment for 1996. 
EPA 453/R-01-003; January 2001; page 85.
---------------------------------------------------------------------------

    In addition to the uncertainties highlighted above, there are 
several factors specific to the acute exposure assessment that the EPA 
conducts as part of the risk review under section 112 of the CAA that 
should be highlighted. The accuracy of an acute inhalation exposure 
assessment depends on the simultaneous occurrence of independent 
factors that may vary greatly, such as hourly emissions rates, 
meteorology and the presence of humans at the location of the maximum 
concentration. In the acute screening assessment that we conduct under 
the RTR program, we assume that peak emissions from the source category 
and worst-case meteorological conditions co-occur, thus, resulting in 
maximum ambient concentrations. These two events are unlikely to occur 
at the same time, making these assumptions conservative. We then 
include the additional assumption that a person is located at this 
point during this same time period. For this source category, these 
assumptions would tend to be worst-case actual exposures as it is 
unlikely that a person would be located at the point of maximum 
exposure during the time when peak emissions and worst-case 
meteorological conditions occur simultaneously.
d. Uncertainties in Dose-Response Relationships
    There are uncertainties inherent in the development of the dose-
response values used in our risk assessments for cancer effects from 
chronic exposures and non-cancer effects from both chronic and acute 
exposures. Some uncertainties may be considered quantitatively, and 
others generally are expressed in qualitative terms. We note as a 
preface to this discussion a point on dose-response uncertainty that is 
brought out in the EPA's 2005 Cancer Guidelines; namely, that ``the 
primary goal of EPA actions is protection of human health; accordingly, 
as an Agency policy, risk assessment procedures, including default 
options that are used in the absence of scientific data to the 
contrary, should be health protective'' (EPA 2005 Cancer Guidelines, 
pages 1-7). This is the approach followed here as summarized in the 
next several paragraphs. A complete detailed discussion of 
uncertainties and variability in dose-response relationships is given 
in the Residual Risk Assessment for the Aerospace Manufacturing and 
Rework Facilities Source Category in Support of the January, 2015 Risk 
and Technology Review Proposal, January 2015, which is available in the 
docket for this action.
    Cancer URE values used in our risk assessments are those that have 
been developed to generally provide an upper bound estimate of risk. 
That is, they represent a ``plausible upper limit to the true value of 
a quantity'' (although this is usually not a true statistical 
confidence limit).\20\ In some circumstances, the true risk could be as 
low as zero; however, in other circumstances the risk could be 
greater.\21\ When developing an upper bound estimate of risk and to 
provide risk values that do not underestimate risk, health-protective 
default approaches are generally used. To err on the side of ensuring 
adequate health protection, the EPA typically uses the upper bound 
estimates rather than lower bound or central tendency estimates in our 
risk assessments, an approach that may have limitations for other uses 
(e.g., priority-setting or expected benefits analysis).
---------------------------------------------------------------------------

    \20\ IRIS glossary (https://www.epa.gov/NCEA/iris/help_gloss.htm).
    \21\ An exception to this is the URE for benzene, which is 
considered to cover a range of values, each end of which is 
considered to be equally plausible, and which is based on maximum 
likelihood estimates.
---------------------------------------------------------------------------

    Chronic non-cancer RfC and reference dose (RfD) values represent 
chronic exposure levels that are intended to be health-protective 
levels. Specifically, these values provide an estimate (with 
uncertainty spanning perhaps an order of magnitude) of a continuous 
inhalation exposure (RfC) or a daily oral exposure (RfD) to the human 
population

[[Page 8408]]

(including sensitive subgroups) that is likely to be without an 
appreciable risk of deleterious effects during a lifetime. To derive 
values that are intended to be ``without appreciable risk,'' the 
methodology relies upon an uncertainty factor (UF) approach (U.S. EPA, 
1993, 1994) 22 23 which considers uncertainty, variability 
and gaps in the available data. The UF are applied to derive reference 
values that are intended to protect against appreciable risk of 
deleterious effects. The UF are commonly default values \24\ (e.g., 
factors of 10 or 3) used in the absence of compound-specific data; 
where data are available, UF may also be developed using compound-
specific information. When data are limited, more assumptions are 
needed and more UF are used. Thus, there may be a greater tendency to 
overestimate risk in the sense that further study might support 
development of reference values that are higher (i.e., less potent) 
because fewer default assumptions are needed. However, for some 
pollutants, it is possible that risks may be underestimated.
---------------------------------------------------------------------------

    \22\ U.S. EPA. Reference Dose (RfD): Description and Use in 
Health Risk Assessments. Dated March 1993.
    \23\ U.S. EPA. Methods for Derivation of Inhalation Reference 
Concentrations and Application of Inhalation Dosimetry. EPA/600/8-
90/066F. Dated October 1994.
    \24\ According to the NRC report, Science and Judgment in Risk 
Assessment (NRC, 1994) ``[Default] options are generic approaches, 
based on general scientific knowledge and policy judgment, that are 
applied to various elements of the risk assessment process when the 
correct scientific model is unknown or uncertain.'' The 1983 NRC 
report, Risk Assessment in the Federal Government: Managing the 
Process, defined default option as ``the option chosen on the basis 
of risk assessment policy that appears to be the best choice in the 
absence of data to the contrary'' (NRC, 1983a, p. 63). Therefore, 
default options are not rules that bind the agency; rather, the 
agency may depart from them in evaluating the risks posed by a 
specific substance when it believes this to be appropriate. In 
keeping with EPA's goal of protecting public health and the 
environment, default assumptions are used to ensure that risk to 
chemicals is not underestimated (although defaults are not intended 
to overtly overestimate risk). See EPA, 2004, An Examination of EPA 
Risk Assessment Principles and Practices, EPA/100/B-04/001 available 
at: https://www.epa.gov/osa/pdfs/ratf-final.pdf.
---------------------------------------------------------------------------

    While collectively termed ``UF,'' these factors account for a 
number of different quantitative considerations when using observed 
animal (usually rodent) or human toxicity data in the development of 
the RfC. The UF are intended to account for: (1) Variation in 
susceptibility among the members of the human population (i.e., inter-
individual variability); (2) uncertainty in extrapolating from 
experimental animal data to humans (i.e., interspecies differences); 
(3) uncertainty in extrapolating from data obtained in a study with 
less-than-lifetime exposure (i.e., extrapolating from sub-chronic to 
chronic exposure); (4) uncertainty in extrapolating the observed data 
to obtain an estimate of the exposure associated with no adverse 
effects; and (5) uncertainty when the database is incomplete or there 
are problems with the applicability of available studies.
    Many of the UF used to account for variability and uncertainty in 
the development of acute reference values are quite similar to those 
developed for chronic durations, but they more often use individual UF 
values that may be less than 10. The UF are applied based on chemical-
specific or health effect-specific information (e.g., simple irritation 
effects do not vary appreciably between human individuals, hence a 
value of 3 is typically used), or based on the purpose for the 
reference value (see the following paragraph). The UF applied in acute 
reference value derivation include: (1) Heterogeneity among humans; (2) 
uncertainty in extrapolating from animals to humans; (3) uncertainty in 
lowest observed adverse effect (exposure) level to no observed adverse 
effect (exposure) level adjustments; and (4) uncertainty in accounting 
for an incomplete database on toxic effects of potential concern. 
Additional adjustments are often applied to account for uncertainty in 
extrapolation from observations at one exposure duration (e.g., 4 
hours) to derive an acute reference value at another exposure duration 
(e.g., 1 hour).
    Not all acute reference values are developed for the same purpose 
and care must be taken when interpreting the results of an acute 
assessment of human health effects relative to the reference value or 
values being exceeded. Where relevant to the estimated exposures, the 
lack of short-term dose-response values at different levels of severity 
should be factored into the risk characterization as potential 
uncertainties.
    For a group of compounds that are unspeciated (e.g., glycol 
ethers), we conservatively use the most protective reference value of 
an individual compound in that group to estimate risk. Similarly, for 
an individual compound in a group (e.g., ethylene glycol diethyl ether) 
that does not have a specified reference value, we also apply the most 
protective reference value from the other compounds in the group to 
estimate risk.
e. Uncertainties in the Multipathway Assessment
    For each source category, we generally rely on site-specific levels 
of PB-HAP emissions to determine whether a refined assessment of the 
impacts from multipathway exposures is necessary. This determination is 
based on the results of a three-tiered screening analysis that relies 
on the outputs from models that estimate environmental pollutant 
concentrations and human exposures for four PB-HAP. Two important types 
of uncertainty associated with the use of these models in RTR risk 
assessments and inherent to any assessment that relies on environmental 
modeling are model uncertainty and input uncertainty.\25\
---------------------------------------------------------------------------

    \25\ In the context of this discussion, the term ``uncertainty'' 
as it pertains to exposure and risk encompasses both variability in 
the range of expected inputs and screening results due to existing 
spatial, temporal and other factors, as well as uncertainty in being 
able to accurately estimate the true result.
---------------------------------------------------------------------------

    Model uncertainty concerns whether the selected models are 
appropriate for the assessment being conducted and whether they 
adequately represent the actual processes that might occur for that 
situation. An example of model uncertainty is the question of whether 
the model adequately describes the movement of a pollutant through the 
soil. This type of uncertainty is difficult to quantify. However, based 
on feedback received from previous EPA SAB reviews and other reviews, 
we are confident that the models used in the screen are appropriate and 
state-of-the-art for the multipathway risk assessments conducted in 
support of RTR.
    Input uncertainty is concerned with how accurately the models have 
been configured and parameterized (i.e., represented in terms of 
measurable or estimable variables) for the assessment at hand. For Tier 
1 of the multipathway screen, we configured the models to avoid 
underestimating exposure and risk. This was accomplished by selecting 
upper-end values from nationally representative datasets for the more 
influential parameters in the environmental model, including selection 
and spatial configuration of the area of interest, lake location and 
size, meteorology, surface water and soil characteristics and structure 
of the aquatic food web. We also assume an ingestion exposure scenario 
and values for human exposure factors that represent reasonable maximum 
exposures.
    In Tier 2 of the multipathway assessment, we refine the model 
inputs to account for meteorological patterns in the vicinity of the 
facility versus using upper-end national values and we identify the 
actual location of lakes near the facility rather than the default lake 
location that we apply in Tier 1. By

[[Page 8409]]

refining the screening approach in Tier 2 to account for local 
geographical and meteorological data, we decrease the likelihood that 
concentrations in environmental media are overestimated, thereby 
increasing the usefulness of the screen. The assumptions and the 
associated uncertainties regarding the selected ingestion exposure 
scenario are the same for Tier 1 and Tier 2.
    For both Tiers 1 and 2 of the multipathway assessment, our approach 
to addressing model input uncertainty is generally cautious. We choose 
model inputs from the upper end of the range of possible values for the 
influential parameters used in the models, and we assume that the 
exposed individual exhibits ingestion behavior that would lead to a 
high total exposure. This approach reduces the likelihood of not 
identifying high risks for adverse impacts.
    Despite the uncertainties, when individual pollutants or facilities 
do screen out, we are confident that the potential for adverse 
multipathway impacts on human health is very low. On the other hand, 
when individual pollutants or facilities do not screen out, it does not 
mean that multipathway impacts are significant, only that we cannot 
rule out that possibility and that a refined multipathway analysis for 
the site might be necessary to obtain a more accurate risk 
characterization for the source category.
    For further information on uncertainties and the Tier 1 and 2 
screening methods, refer to Appendix 4 of Modeling File Preparation 
Memo.
f. Uncertainties in the Environmental Risk Screening Assessment
    For each source category, we generally rely on site-specific levels 
of environmental HAP emissions to perform an environmental screening 
assessment. The environmental screening assessment is based on the 
outputs from models that estimate environmental HAP concentrations. The 
same models, specifically the TRIM.FaTE multipathway model and the 
AERMOD air dispersion model, are used to estimate environmental HAP 
concentrations for both the human multipathway screening analysis and 
for the environmental screening analysis. Therefore, both screening 
assessments have similar modeling uncertainties.
    Two important types of uncertainty associated with the use of these 
models in RTR environmental screening assessments--and inherent to any 
assessment that relies on environmental modeling--are model uncertainty 
and input uncertainty.\26\
---------------------------------------------------------------------------

    \26\ In the context of this discussion, the term 
``uncertainty,'' as it pertains to exposure and risk assessment, 
encompasses both variability in the range of expected inputs and 
screening results due to existing spatial, temporal and other 
factors, as well as uncertainty in being able to accurately estimate 
the true result.
---------------------------------------------------------------------------

    Model uncertainty concerns whether the selected models are 
appropriate for the assessment being conducted and whether they 
adequately represent the movement and accumulation of environmental HAP 
emissions in the environment. For example, does the model adequately 
describe the movement of a pollutant through the soil? This type of 
uncertainty is difficult to quantify. However, based on feedback 
received from previous EPA SAB reviews and other reviews, we are 
confident that the models used in the screen are appropriate and state-
of-the-art for the environmental risk assessments conducted in support 
of our RTR analyses.
    Input uncertainty is concerned with how accurately the models have 
been configured and parameterized for the assessment at hand. For Tier 
1 of the environmental screen for PB-HAP, we configured the models to 
avoid underestimating exposure and risk to reduce the likelihood that 
the results indicate the risks are lower than they actually are. This 
was accomplished by selecting upper-end values from nationally-
representative datasets for the more influential parameters in the 
environmental model, including selection and spatial configuration of 
the area of interest, the location and size of any bodies of water, 
meteorology, surface water and soil characteristics and structure of 
the aquatic food web. In Tier 1, we used the maximum facility-specific 
emissions for the PB-HAP (other than lead compounds, which were 
evaluated by comparison to the secondary lead NAAQS) that were included 
in the environmental screening assessment and each of the media when 
comparing to ecological benchmarks. This is consistent with the 
conservative design of Tier 1 of the screen. In Tier 2 of the 
environmental screening analysis for PB-HAP, we refine the model inputs 
to account for meteorological patterns in the vicinity of the facility 
versus using upper-end national values, and we identify the locations 
of water bodies near the facility location. By refining the screening 
approach in Tier 2 to account for local geographical and meteorological 
data, we decrease the likelihood that concentrations in environmental 
media are overestimated, thereby increasing the usefulness of the 
screen. To better represent widespread impacts, the modeled soil 
concentrations are averaged in Tier 2 to obtain one average soil 
concentration value for each facility and for each PB-HAP. For PB-HAP 
concentrations in water, sediment and fish tissue, the highest value 
for each facility for each pollutant is used.
    For the environmental screening assessment for acid gases, we 
employ a single-tiered approach. We use the modeled air concentrations 
and compare those with ecological benchmarks.
    For both Tiers 1 and 2 of the environmental screening assessment, 
our approach to addressing model input uncertainty is generally 
cautious. We choose model inputs from the upper end of the range of 
possible values for the influential parameters used in the models, and 
we assume that the exposed individual exhibits ingestion behavior that 
would lead to a high total exposure. This approach reduces the 
likelihood of not identifying potential risks for adverse environmental 
impacts.
    Uncertainty also exists in the ecological benchmarks for the 
environmental risk screening analysis. We established a hierarchy of 
preferred benchmark sources to allow selection of benchmarks for each 
environmental HAP at each ecological assessment endpoint. In general, 
EPA benchmarks for programmatic levels (e.g., Office of Water, 
Superfund Program) were used if available. If not, we used EPA 
benchmarks used in regional programs (e.g., Superfund Program). If 
benchmarks were not available at a programmatic or regional level, we 
used benchmarks developed by other agencies (e.g., NOAA) or by state 
agencies.
    In all cases (except for lead compounds, which were evaluated 
through a comparison to the NAAQS), we searched for benchmarks at the 
following three effect levels, as described in section III.A.5 of this 
preamble:
    1. A no-effect level (i.e., NOAEL).
    2. Threshold-effect level (i.e., LOAEL).
    3. Probable effect level (i.e., PEL).
    For some ecological assessment endpoint/environmental HAP 
combinations, we could identify benchmarks for all three effect levels, 
but for most, we could not. In one case, where different agencies 
derived significantly different numbers to represent a threshold for 
effect, we included both. In several cases, only a single benchmark was 
available. In cases where multiple effect levels were

[[Page 8410]]

available for a particular PB-HAP and assessment endpoint, we used all 
of the available effect levels to help us to determine whether risk 
exists and if the risks could be considered significant and widespread.
    The EPA evaluates the following seven HAP in the environmental risk 
screening assessment: Cadmium, dioxins/furans, POM, mercury (both 
inorganic mercury and methyl mercury), lead compounds, HCl and HF, 
where applicable. These seven HAP represent pollutants that can cause 
adverse impacts for plants and animals either through direct exposure 
to HAP in the air or through exposure to HAP that is deposited from the 
air onto soils and surface waters. These seven HAP also represent those 
HAP for which we can conduct a meaningful environmental risk screening 
assessment. For other HAP not included in our screening assessment, the 
model has not been parameterized such that it can be used for that 
purpose. In some cases, depending on the HAP, we may not have 
appropriate multipathway models that allow us to predict the 
concentration of that pollutant. The EPA acknowledges that other HAP 
beyond the seven HAP that we are evaluating may have the potential to 
cause adverse environmental effects and, therefore, the EPA may 
evaluate other relevant HAP in the future, as modeling science and 
resources allow.
    Further information on uncertainties and the Tier 1 and 2 
environmental screening methods is provided in Appendix 5 of the 
document, Technical Support Document for TRIM-Based Multipathway Tiered 
Screening Methodology for RTR: Summary of Approach and Evaluation. 
Also, see the Residual Risk Assessment for the Aerospace Manufacturing 
and Rework Facilities Source Category in Support of the January, 2015 
Risk and Technology Review Proposal, January 2015, available in the 
docket for this action.

B. How did we consider the risk results in making decisions for this 
proposal?

    As discussed in section II.A of this preamble, in evaluating and 
developing standards under CAA section 112(f)(2), we apply a two-step 
process to address residual risk. In the first step, the EPA determines 
whether risks are acceptable. This determination ``considers all health 
information, including risk estimation uncertainty, and includes a 
presumptive limit on maximum individual lifetime [cancer] risk (MIR) 
\27\ of approximately [1-in-10 thousand] [i.e., 100-in-1 million].'' 54 
FR 38045, September 14, 1989. If risks are unacceptable, the EPA must 
determine the emissions standards necessary to bring risks to an 
acceptable level without considering costs. In the second step of the 
process, the EPA considers whether the emissions standards provide an 
ample margin of safety ``in consideration of all health information, 
including the number of persons at risk levels higher than 
approximately 1-in-1 million, as well as other relevant factors, 
including costs and economic impacts, technological feasibility, and 
other factors relevant to each particular decision.'' Id. The EPA must 
promulgate emission standards necessary to provide an ample margin of 
safety.
---------------------------------------------------------------------------

    \27\ Although defined as ``maximum individual risk,'' MIR refers 
only to cancer risk. MIR, one metric for assessing cancer risk, is 
the estimated risk were an individual exposed to the maximum level 
of a pollutant for a lifetime.
---------------------------------------------------------------------------

    In past residual risk actions, the EPA considered a number of human 
health risk metrics associated with emissions from the categories under 
review, including the MIR, the number of persons in various risk 
ranges, cancer incidence, the maximum non-cancer HI and the maximum 
acute non-cancer hazard. See, e.g., 72 FR 25138, May 3, 2007; 71 FR 
42724, July 27, 2006. The EPA considered this health information for 
both actual and allowable emissions. See, e.g., 75 FR 65068, October 
21, 2010; 75 FR 80220, December 21, 2010; 76 FR 29032, May 19, 2011. 
The EPA also discussed risk estimation uncertainties and considered the 
uncertainties in the determination of acceptable risk and ample margin 
of safety in these past actions. The EPA considered this same type of 
information in support of this action.
    The agency is considering these various measures of health 
information to inform our determinations of risk acceptability and 
ample margin of safety under CAA section 112(f). As explained in the 
Benzene NESHAP, ``the first step judgment on acceptability cannot be 
reduced to any single factor'' and, thus, ``[t]he Administrator 
believes that the acceptability of risk under [previous] section 112 is 
best judged on the basis of a broad set of health risk measures and 
information.'' 54 FR 38046, September 14, 1989. Similarly, with regard 
to the ample margin of safety determination, ``the Agency again 
considers all of the health risk and other health information 
considered in the first step. Beyond that information, additional 
factors relating to the appropriate level of control will also be 
considered, including cost and economic impacts of controls, 
technological feasibility, uncertainties, and any other relevant 
factors.'' Id.
    The Benzene NESHAP approach provides flexibility regarding factors 
the EPA may consider in making determinations and how the EPA may weigh 
those factors for each source category. In responding to comment on our 
policy under the Benzene NESHAP, the EPA explained that:

[t]he policy chosen by the Administrator permits consideration of 
multiple measures of health risk. Not only can the MIR figure be 
considered, but also incidence, the presence of non-cancer health 
effects, and the uncertainties of the risk estimates. In this way, 
the effect on the most exposed individuals can be reviewed as well 
as the impact on the general public. These factors can then be 
weighed in each individual case. This approach complies with the 
Vinyl Chloride mandate that the Administrator ascertain an 
acceptable level of risk to the public by employing [her] expertise 
to assess available data. It also complies with the Congressional 
intent behind the CAA, which did not exclude the use of any 
particular measure of public health risk from the EPA's 
consideration with respect to CAA section 112 regulations, and 
thereby implicitly permits consideration of any and all measures of 
health risk which the Administrator, in [her] judgment, believes are 
appropriate to determining what will `protect the public health'.

See 54 FR at 38057, September 14, 1989. Thus, the level of the MIR is 
only one factor to be weighed in determining acceptability of risks. 
The Benzene NESHAP explained that ``an MIR of approximately 1-in-10 
thousand should ordinarily be the upper end of the range of 
acceptability. As risks increase above this benchmark, they become 
presumptively less acceptable under CAA section 112, and would be 
weighed with the other health risk measures and information in making 
an overall judgment on acceptability. Or, the Agency may find, in a 
particular case, that a risk that includes MIR less than the 
presumptively acceptable level is unacceptable in the light of other 
health risk factors.'' Id. at 38045. Similarly, with regard to the 
ample margin of safety analysis, the EPA stated in the Benzene NESHAP 
that: ``EPA believes the relative weight of the many factors that can 
be considered in selecting an ample margin of safety can only be 
determined for each specific source category. This occurs mainly 
because technological and economic factors (along with the health-
related factors) vary from source category to source category.'' Id. at 
38061. We also consider the uncertainties associated with the various 
risk analyses, as discussed earlier in this preamble, in

[[Page 8411]]

our determinations of acceptability and ample margin of safety.
    The EPA notes that it has not considered certain health information 
to date in making residual risk determinations. At this time, we do not 
attempt to quantify those HAP risks that may be associated with 
emissions from other facilities that do not include the source 
categories in question, mobile source emissions, natural source 
emissions, persistent environmental pollution or atmospheric 
transformation in the vicinity of the sources in these categories.
    The agency understands the potential importance of considering an 
individual's total exposure to HAP in addition to considering exposure 
to HAP emissions from the source category and facility. We recognize 
that such consideration may be particularly important when assessing 
non-cancer risks, where pollutant-specific exposure health reference 
levels (e.g., RfCs) are based on the assumption that thresholds exist 
for adverse health effects. For example, the agency recognizes that, 
although exposures attributable to emissions from a source category or 
facility alone may not indicate the potential for increased risk of 
adverse non-cancer health effects in a population, the exposures 
resulting from emissions from the facility in combination with 
emissions from all of the other sources (e.g., other facilities) to 
which an individual is exposed may be sufficient to result in increased 
risk of adverse non-cancer health effects. In May 2010, the SAB advised 
the EPA ``that RTR assessments will be most useful to decision makers 
and communities if results are presented in the broader context of 
aggregate and cumulative risks, including background concentrations and 
contributions from other sources in the area.'' \28\
---------------------------------------------------------------------------

    \28\ EPA's responses to this and all other key recommendations 
of the SAB's advisory on RTR risk assessment methodologies (which is 
available at: https://yosemite.epa.gov/sab/sabproduct.nsf/
4AB3966E263D943A8525771F00668381/$File/EPA-SAB-10-007-unsigned.pdf) 
are outlined in a memo to this rulemaking docket from David Guinnup 
entitled, EPA's Actions in Response to the Key Recommendations of 
the SAB Review of RTR Risk Assessment Methodologies.
---------------------------------------------------------------------------

    In response to the SAB recommendations, the EPA is incorporating 
cumulative risk analyses into its RTR risk assessments, including those 
reflected in this proposal. The agency is: (1) Conducting facility-wide 
assessments, which include source category emission points as well as 
other emission points within the facilities; (2) considering sources in 
the same category whose emissions result in exposures to the same 
individuals; and (3) for some persistent and bioaccumulative 
pollutants, analyzing the ingestion route of exposure. In addition, the 
RTR risk assessments have always considered aggregate cancer risk from 
all carcinogens and aggregate non-cancer hazard indices from all non-
carcinogens affecting the same target organ system.
    Although we are interested in placing source category and facility-
wide HAP risks in the context of total HAP risks from all sources 
combined in the vicinity of each source, we are concerned about the 
uncertainties of doing so. Because of the contribution to total HAP 
risk from emission sources other than those that we have studied in 
depth during this RTR review, such estimates of total HAP risks would 
have significantly greater associated uncertainties than the source 
category or facility-wide estimates. Such aggregate or cumulative 
assessments would compound those uncertainties, making the assessments 
too unreliable.

C. How did we perform the technology review?

    Our technology review focused on the identification and evaluation 
of developments in practices, processes and control technologies that 
have occurred since the MACT standards were promulgated. Where we 
identified such developments, in order to inform our decision of 
whether it is ``necessary'' to revise the emissions standards, we 
analyzed the technical feasibility of applying these developments and 
the estimated costs, energy implications, non-air environmental 
impacts, as well as considering the emission reductions. We also 
considered the appropriateness of applying controls to new sources 
versus retrofitting existing sources.
    Based on our analyses of the available data and information, we 
identified potential developments in practices, processes and control 
technologies. For this exercise, we considered any of the following to 
be a ``development'':
     Any add-on control technology or other equipment that was 
not identified and considered during development of the original MACT 
standards.
     Any improvements in add-on control technology or other 
equipment (that were identified and considered during development of 
the original MACT standards) that could result in additional emissions 
reduction.
     Any work practice or operational procedure that was not 
identified or considered during development of the original MACT 
standards.
     Any process change or pollution prevention alternative 
that could be broadly applied to the industry and that was not 
identified or considered during development of the original MACT 
standards.
     Any significant changes in the cost (including cost 
effectiveness) of applying controls (including controls the EPA 
considered during the development of the original MACT standards).
    We reviewed a variety of data sources in our investigation of 
potential practices, processes or controls to consider. Among the 
sources we reviewed were the NESHAP for various industries that were 
promulgated since the MACT standards being reviewed in this action. We 
reviewed the regulatory requirements and/or technical analyses 
associated with these regulatory actions to identify any practices, 
processes and control technologies considered in these efforts that 
could be applied to emission sources in the Aerospace Manufacturing and 
Rework Facilities source category, as well as the costs, non-air 
impacts and energy implications associated with the use of these 
technologies. Additionally, we requested information from facilities 
regarding developments in practices, processes or control technology. 
Finally, we reviewed information from other sources, such as state and/
or local permitting agency databases and industry-supported databases.

IV. Analytical Results and Proposed Decisions

A. What actions are we taking pursuant to CAA sections 112(d)(2) and 
112(d)(3)?

    We are not proposing any new emissions limitations to the NESHAP 
other than with respect to specialty coatings. In this action, we are 
proposing the following revisions to the Aerospace NESHAP to ensure the 
standards are consistent with the requirements of the CAA as 
interpreted by the courts: adding standards to limit organic and 
inorganic HAP emissions from specialty coating application operations 
and updating the provisions regulating emissions during periods of SSM. 
Additionally, we are adding an alternative compliance demonstration 
provision for all types of coating application operations (primers, 
topcoats, specialty coatings and chemical milling maskants) in certain 
situations. The results and proposed decisions based on the analyses 
performed pursuant to CAA section 112(d)(2) and (3) are presented 
below.
    We are proposing to establish MACT standards specific to specialty 
coating application operations to ensure the standards are consistent 
with the

[[Page 8412]]

requirements of the CAA as interpreted by the courts. Under CAA section 
112(d)(3), the EPA is required to promulgate emissions limits for all 
HAP emitted from major source categories.\29\ Specialty coatings are a 
source of HAP emissions from the Aerospace Manufacturing and Rework 
Facilities source category that is not currently regulated under the 
Aerospace NESHAP. We are proposing organic HAP content limits to reduce 
organic HAP emissions and equipment and work practice standards to 
reduce inorganic HAP emissions associated with specialty coating 
application. Refer to section IV.E.1 of this preamble for a description 
of specialty coating application operations, associated emissions and 
how this emissions source is addressed in the current Aerospace NESHAP, 
and how the EPA established the MACT floor for specialty coating 
application operations. Section IV.E.1 of this preamble also includes 
the EPA's rationale for proposing this standard, as well as how the EPA 
established the MACT floor for specialty coating application operations 
and the estimated costs for complying with the proposed standard. The 
EPA is proposing to add these standards for specialty coatings because 
they are a source of HAP emissions from the Aerospace Manufacturing and 
Rework Facilities source category and EPA had not previously 
established MACT standards for these emissions points. These proposed 
changes are necessary to ensure the emissions standards are consistent 
with the requirements of the CAA as interpreted by the courts and are 
unrelated to the risk findings.
---------------------------------------------------------------------------

    \29\ For more details see the discussion of Sierra Club v. EPA, 
479 F. 3d 875 (D.C. Cir. 2007) in section II.E of this preamble, 
which found that the EPA may not set ``no emissions reductions'' 
MACT floors.
---------------------------------------------------------------------------

    The EPA is also proposing to revise the provisions affecting 
periods of SSM to clarify that the emission limitations in the 
Aerospace NESHAP apply at all times, including during these SSM 
periods. Refer to section IV.E.3 of this preamble for a description of 
the EPA's proposed revisions to the SSM provisions for aerospace 
manufacturing and rework operations. These proposed changes to the SSM 
provisions are necessary to ensure the emissions standards are 
consistent with the requirements of the CAA as interpreted by the 
courts and are unrelated to the risk findings.
    The EPA also collected emissions data and performed a risk analysis 
for certain emissions points outside of the source category--chemical 
milling and metal finishing operations, waste water operations, storage 
tanks and composite operations that are related to aerospace 
manufacturing and rework, but are not surface coating operations. The 
data collected for these non-surface coating operations were used to 
characterize the risk presented from these operations in order to 
estimate the total risk from the entirety of each aerospace 
manufacturing and rework facility. The EPA is not proposing to expand 
the Aerospace Manufacturing and Rework Facilities source category to 
include these operations, which are not surface coating operations and 
were not part of the original source category and which, as explained 
below, did not present unacceptable risks. The initial and subsequent 
listings of source categories for regulation under section 112 of the 
CAA included Aerospace Manufacturing and Rework Facilities only as a 
surface coating source category.\30\ \31\
---------------------------------------------------------------------------

    \30\ Initial List of Categories of Sources Under Section 
112(c)(1) of the Clean Air Act Amendments of 1990. 57 FR 31576, July 
17, 1992.
    \31\ National Emission Standards for Hazardous Air Pollutants; 
Revision of Initial List of Categories of Sources and Schedule for 
Standards Under Sections 112(c) and (e) of the Clean Air Act 
Amendments of 1990. 61 FR 28197, June 4, 1996.
---------------------------------------------------------------------------

B. What are the results of the risk assessment and analyses?

1. Inhalation Risk Assessment Results
    Table 2 of this preamble provides an overall summary of the results 
of the inhalation risk assessment.

            Table 2--Aerospace Manufacturing and Rework Facilities Inhalation Risk Assessment Results
----------------------------------------------------------------------------------------------------------------
                                                        Estimated
                              Estimated  population  annual  cancer      Maximum
Maximum  individual  cancer    at  increased risk       incidence     chronic  non-  Maximum screening acute non-
 risk  (-in-1 million) \a\      levels of cancer       (cases per     cancer  TOSHI         cancer HQ \c\
                                                          year)            \b\
----------------------------------------------------------------------------------------------------------------
                                                Actual Emissions
----------------------------------------------------------------------------------------------------------------
10.........................  >= 1-in-1 million:                0.02             0.5  HQREL = 2 (ethylene glycol
                              180,000.                                                ethyl ether acetate).
                             >= 10-in-1 million:
                              1,500.
                             >= 100-in-1 million: 0
----------------------------------------------------------------------------------------------------------------
                                             Allowable Emissions \d\
----------------------------------------------------------------------------------------------------------------
10.........................  >= 1-in-1 million:                0.02             0.5  ...........................
                              180,000.
                             >= 10-in-1 million:
                              2,000.
                             >= 100-in-1 million: 0
----------------------------------------------------------------------------------------------------------------
\a\ Estimated maximum individual excess lifetime cancer risk due to HAP emissions from the source category.
\b\ Maximum TOSHI. The target organ with the highest TOSHI for the Aerospace Manufacturing and Rework Facilities
  source category for both actual and allowable emissions is the kidney system.
\c\ See Section III.A.3 of this preamble for explanation of acute dose-response values. Acute assessments are
  not performed on allowable emissions.
\d\ The development of allowable emission estimates can be found in the memorandum titled, Aerospace
  Manufacturing and Rework Facilities RTR Modeling File Preparation, December 2014, which is available in the
  docket.

    The inhalation risk modeling performed to estimate risks based on 
actual and allowable emissions relied primarily on emissions data from 
the ICRs and calculations described in the memorandum titled, Aerospace

[[Page 8413]]

Manufacturing and Rework Facilities RTR Modeling File Preparation, 
December 2014, which is available in the docket for this action. The 
results of the chronic baseline inhalation cancer risk assessment 
indicate that, based on estimates of current actual emissions, the MIR 
posed by the Aerospace Manufacturing and Rework Facilities is 10-in-1 
million, with emissions of strontium chromate, from coating operations 
accounting for the majority of the risk. The total estimated cancer 
incidence from Aerospace Manufacturing and Rework Facilities based on 
actual emission levels is 0.02 excess cancer cases per year or one case 
every 50 years, with emissions of strontium chromate and chromium 
compounds contributing 66 percent and 15 percent, respectively, to the 
cancer incidence. In addition, we note that approximately 1,500 people 
are estimated to have cancer risks greater than or equal to 10-in-1 
million, and approximately 180,000 people are estimated to have risks 
greater than or equal to 1-in-1 million as a result of actual emissions 
from this source category.
    When considering MACT-allowable emissions, the MIR is estimated to 
be up to 10-in-1 million, driven by emissions of strontium chromate 
from coating operations. The estimated cancer incidence is estimated to 
be 0.02 excess cancer cases per year, or one excess case in every 50 
years. Approximately 2,000 people are estimated to have cancer risks 
greater than or equal to 10-in-1 million and approximately 180,000 
people are estimated to have cancer risks greater than or equal to 1-
in-1 million considering allowable emissions from Aerospace 
Manufacturing and Rework Facilities.
    The maximum modeled chronic non-cancer HI (TOSHI) value for the 
source category based on actual emissions is estimated to be 0.5, 
driven by cadmium compounds emissions from blast depainting. When 
considering MACT-allowable emissions, the maximum chronic non-cancer 
TOSHI value is estimated to be 0.5, also driven by cadmium compounds 
emissions from blast depainting.
2. Acute Risk Results
    Our screening analysis for worst-case acute impacts based on actual 
emissions indicates the potential for one pollutant, ethylene glycol 
ethyl ether acetate, from one facility, to have HQ values above 1, 
based on its REL value. One hundred forty-three of the 144 Aerospace 
Manufacturing and Rework Facilities had an estimated worst-case HQ less 
than or equal to 1 for all HAP.
    To better characterize the potential health risks associated with 
estimated worst-case acute exposures to HAP from the source category at 
issue and in response to a key recommendation from the SAB's peer 
review of the EPA's CAA section 112(f) RTR risk assessment 
methodologies, we examine a wider range of available acute health 
metrics than we do for our chronic risk assessments. This is in 
acknowledgement that there are generally more data gaps and 
inconsistencies in acute reference values than there are in chronic 
reference values.
    By definition, the acute CalEPA REL represents a health-protective 
level of exposure, with no risk anticipated below those levels, even 
for repeated exposures; however, the health risk from higher-level 
exposures is unknown. Therefore, when a CalEPA REL is exceeded and an 
AEGL-1 or ERPG-1 level is available (i.e., levels at which mild effects 
are anticipated in the general public for a single exposure), we have 
used them as a second comparative measure. Historically, comparisons of 
the estimated maximum off-site 1-hour exposure levels have not been 
typically made to occupational levels for the purpose of characterizing 
public health risks in RTR assessments. This is because occupational 
ceiling values are not generally considered protective for the general 
public since they are designed to protect the worker population 
(presumed healthy adults) for short-duration (less than 15-minute) 
increases in exposure. As a result, for most chemicals, the 15-minute 
occupational ceiling values are set at levels higher than a 1-hour 
AEGL-1, making comparisons to them irrelevant unless the AEGL-1 or 
ERPG-1 levels are also exceeded.
    The worst-case maximum estimated 1-hour exposure to ethylene glycol 
ethyl ether acetate outside the facility fence line for the source 
categories is 0.3 mg/m\3\. This estimated worst-case exposure exceeds 
the 1-hour REL by a factor of 2 (HQREL = 2). All other HAP 
in this analysis have worst-case acute HQ values of 1 or less (maximum 
HQAEGL-1 = 0.02 for phenol, maximum HQERPG-1 = 
0.03 for phenol) indicating that they carry no potential to pose acute 
concerns.
    In characterizing the potential for acute non-cancer impacts of 
concern, it is important to remember the upward bias of these exposure 
estimates (e.g., worst-case meteorology coinciding with a person 
located at the point of maximum concentration during the hour) and to 
consider the results along with the conservative estimates used to 
develop peak hourly emissions as described in the Modeling File 
Preparation Memo (which is available in the docket for this action) for 
a detailed description of how the hourly emissions were developed for 
this source category.
3. Multipathway Risk Screening Results
    Results of the worst-case Tier I screening analysis indicate that 
PB-HAP emissions of cadmium compounds or mercury compounds did not 
exceed the screening emission rates. Neither dioxins nor polycyclic 
aromatic hydrocarbons (PAH) are emitted by any source in the source 
category.
4. Environmental Risk Screening Results
    As described in section III.A of this preamble, we conducted a 
screening-level evaluation of the potential adverse environmental risks 
associated with emissions of the following environmental HAP from the 
Aerospace Manufacturing and Rework Facilities source category: lead, 
mercury, cadmium, HCl and HF.
    In the Tier 1 screening analysis for PB-HAP (other than lead 
compounds, which were evaluated differently), the individual modeled 
Tier 1 concentrations for mercury and cadmium did not exceed any 
ecological benchmark for any facility in the source category. For lead 
compounds, we did not estimate any exceedances of the secondary lead 
NAAQS.
    For HF and HCl, the average modeled concentration around each 
facility (i.e., the average concentration of all off-site data points 
in the modeling domain) did not exceed the ecological benchmarks. In 
addition, each individual modeled concentration of HCl and HF (i.e., 
each off-site data point in the modeling domain) was below the 
ecological benchmarks for all facilities.
5. Facility-Wide Risk Results
    The facility-wide chronic MIR and TOSHI were estimated based on 
emissions from all sources at the identified facilities (both MACT and 
non MACT sources). The results of the facility-wide assessment for 
cancer risks indicate that 44 facilities with aerospace manufacturing 
and rework processes have a facility-wide cancer MIR greater than or 
equal to 1-in-1 million. The maximum facility-wide cancer MIR is 20-in-
1 million, primarily driven by arsenic and chromium (VI) compounds, 
from internal combustion engines. The maximum facility-wide TOSHI for 
the source category is estimated to be 0.5, primarily driven by 
emissions of hexamethylene-1,6-diisocyanate from specialty coatings 
operations.

[[Page 8414]]

6. What demographic groups might benefit from this regulation?
    To examine the potential for any environmental justice (EJ) issues 
that might be associated with the source category, we performed a 
demographic analysis, which is an assessment of risks to individual 
demographic groups, of the population close to the facilities. In this 
analysis, we evaluated the distribution of HAP-related cancer risks and 
non-cancer hazards from the Aerospace Manufacturing and Rework 
Facilities across different social, demographic and economic groups 
within the populations living near facilities identified as having the 
highest risks. The methodology and the results of the demographic 
analyses are included in a technical report, Risk and Technology 
Review--Analysis of Socio-Economic Factors for Populations Living Near 
Aerospace Facilities, available in the docket for this action.
    The results of the demographic analysis are summarized in Table 3 
of this preamble. These results, for various demographic groups, are 
based on the estimated risks from actual aerospace manufacturing and 
rework emissions levels for the population living within 50 km of the 
facilities.

            Table 3--Aerospace Manufacturing and Rework Facilities Demographic Risk Analysis Results
----------------------------------------------------------------------------------------------------------------
                                                                                 Population with    Population
                                                                                  cancer risk at   with chronic
                                                                                 or above 1-in-1   hazard index
                                                                   Nationwide     million due to  above 1 due to
                                                                                  emissions from  emissions from
                                                                                    aerospace        aerospace
                                                                                    facilities      facilities
----------------------------------------------------------------------------------------------------------------
Total Population...............................................     312,861,265        179,074                 0
----------------------------------------------------------------------------------------------------------------
                                                 Race by Percent
----------------------------------------------------------------------------------------------------------------
White..........................................................              72             64                NA
All Other Races................................................              28             36                NA
----------------------------------------------------------------------------------------------------------------
                                                 Race by Percent
----------------------------------------------------------------------------------------------------------------
White..........................................................              72             64                NA
African American...............................................              13             19                NA
Native American................................................               1              1.5              NA
Other and Multiracial..........................................              14             16                NA
----------------------------------------------------------------------------------------------------------------
                                              Ethnicity by Percent
----------------------------------------------------------------------------------------------------------------
Hispanic.......................................................              17             16                NA
Non-Hispanic...................................................              83             84                NA
----------------------------------------------------------------------------------------------------------------
                                                Income by Percent
----------------------------------------------------------------------------------------------------------------
Below Poverty Level............................................              14             19                NA
Above Poverty Level............................................              86             81                NA
----------------------------------------------------------------------------------------------------------------
                                              Education by Percent
----------------------------------------------------------------------------------------------------------------
Over 25 and without High School Diploma........................              15             17                NA
Over 25 and with a High School Diploma.........................              85             83                NA
----------------------------------------------------------------------------------------------------------------

    The results of the Aerospace Manufacturing and Rework Facilities 
baseline risk assessment indicate that emissions from the source 
category expose approximately 180,000 people to a cancer risk at or 
above 1-in-1 million and no one is predicted to have a chronic non-
cancer TOSHI greater than 1.
    The analysis indicates that the percentages of the population 
exposed to a cancer risk greater than or equal to 1-in-1 million and 
living within 50 km of the 144 aerospace facilities is higher for 
minority populations, 36-percent exposed versus the national minority 
population average of 28 percent. The specific demographics of the 
population within 50 km of the facilities indicate potential 
disparities in certain demographic groups, including the ``African 
American'' and ``Below the Poverty Level.''

C. What are our proposed decisions regarding risk acceptability, ample 
margin of safety and adverse environmental effects?

1. Risk Acceptability
    As noted in section II.A.1 of this preamble, the EPA sets standards 
under CAA section 112(f)(2) using ``a two-step standard-setting 
approach, with an analytical first step to determine an `acceptable 
risk' that considers all health information, including risk estimation 
uncertainty, and includes a presumptive limit on MIR of approximately 1 
in 10 thousand.'' 54 FR 38045, September 14, 1989. For the Aerospace 
Manufacturing and Rework Facilities source category, we estimate, based 
on both actual and allowable emissions, an MIR of 10-in-1 million 
driven by emissions of strontium chromate from coating operations. We 
estimate that, based on actual emissions, about 1,500 people are 
estimated to have cancer risks greater than or equal to 10-in-1 million 
and, based on allowable emissions, about 2,000 people have cancer risks 
greater than or equal to 10-in-1 million. We estimate that 
approximately 180,000 people are estimated to have risks greater than 
or equal to 1-in-1 million based on both actual and allowable emissions 
from this source category. The total estimated incidence of cancer for 
this source category due to inhalation exposures, based on both actual 
and allowable emissions, is 0.02 excess cancer cases

[[Page 8415]]

per year, or 1 case in 50 years. The agency estimates that the maximum 
chronic non-cancer TOSHI from inhalation exposure, based on both actual 
and allowable emissions, from this source category, is 0.5, with 
cadmium compounds emissions from blast depainting accounting for the 
majority of the TOSHI.
    The multipathway screening analysis, based upon actual emissions, 
indicates that PB-HAP emissions of both cadmium compounds and mercury 
compounds did not exceed the screening emission rates. Neither dioxins 
nor PAH are emitted by any source in the source category. In evaluating 
the potential for multipathway effects from emissions of lead, modeled 
maximum annual lead concentrations were compared to the secondary NAAQS 
for lead (0.15 [mu]g/m\3\). Results of this analysis estimate that the 
NAAQS for lead would not be exceeded at any off-site locations.
    The screening assessment of worst-case acute inhalation impacts 
from baseline actual emissions indicates that the worst-case maximum 
estimated 1-hour exposure to ethylene glycol ethyl ether acetate 
outside the facility fence line exceeds the 1-hour REL by a factor of 2 
(HQREL = 2). This exceedance was only predicted to occur in 
a remote, non-inhabited area just adjacent to the facility fence line 
for 2 hours a year. All other HAP in this analysis have worst-case 
acute HQ values of 1 or less (maximum HQAEGL-1 = 0.02 for 
phenol, maximum HQERPG-1 = 0.03 for phenol) indicating that 
they carry no potential to pose acute concerns.
    In determining whether risks are acceptable for this source 
category, the EPA considered all available health information including 
any uncertainty in risk estimates. Also, as noted above, the agency 
estimated risk from both actual and allowable emissions. While there 
are uncertainties associated with both the actual and allowable 
emissions, we consider the allowable emissions to be an upper bound, 
based on the conservative methods we used to calculate allowable 
emissions.
    The risk results indicate that both the actual and allowable 
inhalation cancer risks to the individual most exposed are no greater 
than approximately 10-in-1 million, which is considerably less than the 
presumptive limit of acceptability (i.e., 100-in-1 million). The 
maximum chronic non-cancer hazard indices for both the actual and 
allowable inhalation non-cancer risks to the individual most exposed of 
0.5 is less than 1.
    The maximum acute non-cancer HQ for all pollutants was 2 based on 
the REL for ethylene glycol ethyl ether acetate. This value was only 
predicted to occur during 2 hours per year in a remote location 
adjacent to a single facility's fenceline. All other acute risks are 
estimated to be below a noncancer HI threshold of 1.
    The multipathway screening analysis indicates that PB-HAP emissions 
did not exceed the screening emission rates for any compound evaluated.
    Considering all of the health risk information and factors 
discussed above, including the uncertainties discussed in section 
III.A.8 of this preamble, the EPA proposes that the risks at baseline 
are acceptable since the cancer risks are well below the presumptive 
limit of acceptability and the non-cancer results indicate there is 
minimal likelihood of adverse non-cancer health effects due to HAP 
emissions from this source category.
2. Ample Margin of Safety Analysis and Proposed Controls
    Under the ample margin of safety analysis, we evaluate the cost and 
feasibility of available control technologies and other measures 
(including the controls, measures and costs evaluated under the 
technology review) that could be applied in this source category to 
further reduce the risks due to emissions of HAP identified in our risk 
assessment, as well as the health impacts of such potential additional 
measures. As noted in our discussion of the technology review in 
section III.C of this preamble, no measures (beyond those already in 
place or that we are proposing today under CAA sections 112 (d)(2) and 
(d)(3)) were identified for reducing HAP emissions from the Aerospace 
Manufacturing and Rework Facilities source category. Therefore, we 
propose that the current standards provide an ample margin of safety to 
protect public health.
    Although the current standards were found to provide an ample 
margin of safety to protect public health, we are proposing additional 
standards under CAA sections 112(d)(2) and (3) that address previously 
unregulated emissions of HAP from specialty coating application 
operations. The additional standards are being proposed to address a 
deficiency in the Aerospace NESHAP as discussed previously in section 
II.E. of this preamble. We are proposing organic HAP and volatile 
organic compound (VOC) content limits for specialty coatings that are 
equal to the VOC content limits specified in the Aerospace CTG for 
specialty coatings. Facilities that do not use specialty coatings and 
those in nonattainment areas that are currently complying with the 
Aerospace CTG limits for their specialty coating operations will not 
have to do anything new to meet these requirements. The 74 facilities 
located in attainment areas that reported using specialty coatings in 
the 2011 ICR may not be using compliant coatings and may need to use 
alternative coatings, direct the emissions stream to an add-on control 
device or use the averaging option to demonstrate compliance with 
implement the standards. We are also proposing that specialty coating 
application operations be subject to the same equipment standards 
(i.e., use high-efficiency application equipment) currently required 
for primer and topcoat application operations. Further, we are 
proposing to require that specialty coating application operations meet 
current work practice standards for primer and topcoat application 
operations for inorganic HAP emissions. The estimated emission 
reductions resulting from these proposed HAP content limits, equipment 
standards and work practice standards for specialty coatings are 58 
tons of HAP per year. As noted above, we are proposing that the MACT 
standard, prior to the implementation of these proposed standards for 
specialty coatings, provides an ample margin of safety to protect 
public health. Therefore, we maintain that, after the implementation of 
these standards for specialty coatings, the rule will continue to 
provide an ample margin of safety to protect public health. 
Consequently, based on current information, we do not expect it will be 
necessary to conduct another residual risk review under CAA section 
112(f) for this source category 8 years following promulgation of new 
emission limits and equipment and work practice standards for specialty 
coatings, merely due to the addition of these MACT requirements. While 
our decisions on risk acceptability and ample margin of safety are 
supported even in the absence of these reductions for specialty 
coatings, if we finalize the proposed requirements for these sources, 
they would further strengthen our conclusions that risk is acceptable 
with an ample margin of safety to protect public health.
    Although we did not identify any new technologies, other than for 
specialty coatings application operations, to reduce risk for this 
source category, we are specifically requesting comment on whether 
there are additional control measures that may be able to reduce risks 
from the source category. We request any information on potential 
emission reductions of such measures, as well the cost and health 
impacts of

[[Page 8416]]

such reductions to the extent they are known.
3. Adverse Environmental Effects
    Based on the results of our environmental risk screening 
assessment, we conclude that there is not an adverse environmental 
effect as a result of HAP emissions from the Aerospace Manufacturing 
and Rework Facilities source category. We are proposing that it is not 
necessary to set a more stringent standard to prevent, taking into 
consideration costs, energy, safety and other relevant factors, an 
adverse environmental effect.

D. What are the results and proposed decisions based on our technology 
review?

    As described in section III.C of this preamble, our technology 
review focused on identifying developments in practices, processes and 
control technologies for the Aerospace Manufacturing and Rework 
Facilities source category. The EPA reviewed various information 
sources regarding emission sources that are currently regulated by the 
Aerospace NESHAP, which include primer and topcoat application 
operations, maskant application operations, cleaning operations, 
chemical and blast depainting operations and waste storage and handling 
operations.
    For the technology review, we conducted a search of the EPA's RACT/
BACT/LAER Clearinghouse (RBLC) and regulatory actions (MACT standards, 
area sources standards and residual risk standards) subsequent to 
promulgation of the 1995 Aerospace NESHAP.\32\ We reviewed Washington 
State's records of Prevention of Significant Deterioration (PSD) 
permits. Further, we considered numerous relevant regional and state 
regulations (e.g., California, Missouri, Delaware and Arizona), the 
Ozone Transport Commission serving the Northeastern United States and 
state implementation plans. We reviewed the database of responses to 
the 2011 ICR to determine the technologies and practices reported by 
industry.
---------------------------------------------------------------------------

    \32\ See the EPA's ``Coatings and Composites Coordinated Rule 
Development'' Web page at https://www.epa.gov/ttnatw01/coat/coat.html 
for a full list of surface coating-related NESHAP, and links to Web 
pages specific to each surface coating NESHAP.
---------------------------------------------------------------------------

    We reviewed these sources for information on add-on control 
technologies, other process equipment, work practices and procedures 
and process changes or pollution prevention alternatives that were not 
considered during development of the Aerospace NESHAP. We also looked 
for information on improvements in add-on control technology, other 
process equipment, work practices and procedures and process changes or 
pollution prevention alternatives that have occurred since development 
of the Aerospace NESHAP. Regarding process changes or pollution 
prevention alternatives, we searched for advancements in the use of 
low-HAP coatings and solvents, advancements in the use of high solids 
coatings and the adoption of lower VOC content limits for coatings and 
solvents.
    The following sections summarize our technology review results for 
each of these emission sources.
1. Primer and Topcoat Application Operations
    As defined in the Aerospace NESHAP (see 40 CFR 63.742), a coating 
is a material that is applied to the surface of an aerospace vehicle or 
component to form a decorative or functional solid film, or the solid 
film itself. A primer is the first layer and any subsequent layers of 
coating prior to the topcoat and is typically used for corrosion 
prevention, protection from the environment, functional fluid 
resistance and adhesion of subsequent coatings. A topcoat is a coating 
that is applied over one or more layers of a primer for appearance, 
identification, camouflage or protection. Specialty coatings are not 
included in the categories of primers or topcoats currently subject to 
regulation under 40 CFR 63.745.
    Most aerospace coatings contain a mixture of organic solvents that 
may be HAP, and also inorganic pigments, such as various metal 
compounds, which may also be HAP. The organic HAP emissions from the 
application of primers and topcoats occur from the evaporation of 
organic solvents during mixing, application and drying. Emissions of 
inorganic HAP from spray-applied coating operations, typically metal 
compounds (e.g., chromium, cadmium compounds), occur when coating 
particles do not adhere to the surface being coated (i.e., overspray). 
The organic and inorganic emissions from coating application occur in 
large open areas, such as hangars or in partially or fully enclosed 
spaces, such as within spray booths.
    The existing Aerospace NESHAP requires the following organic HAP 
and VOC content limits for uncontrolled primers and topcoats (40 CFR 
63.745(c)):
     Primers: 2.9 lb/gal (less water) as applied; or 4.5 lb/gal 
(less water) as applied for general aviation rework facilities, or 5.4 
lb/gal (less water) as applied, to large commercial aircraft components 
(parts or assemblies) or fully assembled, large commercial aircraft.
     Topcoats: 3.5 lb/gal (less water) as applied; or 4.5 lb/
gal (less water) as applied for general aviation rework facilities.
    Alternatively, a control system can be used to capture and control 
organic HAP and VOC emissions from the primer or topcoat application 
operations. The system must achieve an overall control efficiency of 81 
percent of organic HAP and VOC emissions (40 CFR 63.745(d)).
    In addition, the Aerospace NESHAP requires the use of one of the 
following coating application techniques (40 CFR 63.745(f)):
     Flow/curtain coat application.
     Dip coat application.
     Roll coating.
     Brush coating.
     Cotton-tipped swab application.
     Electrodeposition (dip) coating.
     High volume low pressure (HVLP) spraying.
     Electrostatic spray application.
     Other coating application methods that achieve emission 
reductions equivalent to HVLP or electrostatic spray application 
methods.
    The Aerospace NESHAP also includes operating requirements for the 
application of primers or topcoats that contain inorganic HAP, 
including control of spray booth exhaust streams with either 
particulate filters or waterwash spray booths (40 CFR 63.745(g)).
    Based on the technology review for primers and topcoats, we did not 
identify any practices, processes or control technologies beyond those 
already required by the Aerospace NESHAP. A brief summary of the EPA's 
findings in conducting its RTR review of primer and topcoat application 
operations follows. For a detailed discussion of the EPA's findings, 
refer to the memorandum, Technology Review for Primer and Topcoat 
Application Operations in the Aerospace Source Category, January 2015, 
available in the docket for this action.
    In reviewing add-on control technologies or other equipment and 
work practices and procedures, we did not identify any add-on control 
technologies, other equipment or work practices and procedures that had 
not previously been considered during development of the Aerospace 
NESHAP, nor did we identify any developments in the same since the 
promulgation of the NESHAP.
    Based on our search of the RBLC, we did not find any more stringent 
requirements. We identified one facility

[[Page 8417]]

in Washington State, for which a Best Achievable Control Technology 
(BACT) analysis was completed in September 2014, for constructing new 
buildings needed for producing new models of large commercial 
airplanes, including the building and surface coating of composite 
aircraft wings. The surface coating operations on these aircraft wings 
would involve the use of primers and topcoats that are subject to the 
limits in 40 CFR 63.745. The BACT analysis concluded that there are no 
demonstrations of add-on controls at facilities performing surface 
coating comparable to large commercial aircraft wing components. The 
analysis also concluded that add-on controls would not be cost 
effective for surface coating of large components, such as wings, much 
less fully assembled large commercial aircraft.
    In reviewing improvements in add-on control technologies or other 
equipment that had previously been considered during development of the 
Aerospace NESHAP, specifically in conducting a technology review of the 
wood manufacturing industry, we found that the Wood Furniture 
Manufacturing NESHAP, 40 CFR part 63, subpart JJ, requires the use of 
high-efficiency spray guns (e.g., airless spraying, air assisted 
airless spraying, electrostatic spraying and HVLP spray guns) and 
prevents the use of conventional spray guns. Although the Aerospace 
NESHAP does not specifically prohibit the use of conventional spray 
methods, it does specify that only spray application methods that are 
equivalent to HVLP or electrostatic spray application methods may be 
used. Because conventional spray guns can be used only if they can 
achieve the same efficiency as HVLP or electrostatic spray application 
methods, the Aerospace NESHAP and the Wood Furniture Manufacturing 
NESHAP are essentially equivalent. No other new developments in add-on 
control technologies or other equipment were found.
    The EPA reviewed the 2011 ICR data for advancements in the use of 
low-HAP liquid primers and topcoats as process changes and pollution 
prevention alternatives that could be transferred to and used in this 
source category and that were not identified and considered during 
development of the Aerospace NESHAP. In this review, we found some 
facilities with weighted-average HAP content values below the HAP and 
VOC content limits for primers and topcoats in the Aerospace NESHAP. 
However, the data collected by the ICR cannot be compared directly with 
the HAP and VOC content limits in the Aerospace NESHAP because the 
NESHAP limits are based on grams of HAP per liter of coating, less 
water. The ICR asked for readily available data, such as data from 
product sheets and material safety data sheets, which did not provide 
data on the water content of the coatings. As a result, we cannot 
accurately convert the reported HAP contents from the ICR to the same 
basis as in the Aerospace NESHAP. Moreover, we believe that if the 
coatings in the ICR contained water and the water content of the 
coatings is removed, then the corrected HAP content of the coatings 
would increase and the apparent difference between the ICR data and the 
NESHAP limits would be reduced.
    Finally, many of the currently used coatings have already been 
reformulated to meet the current MACT HAP content limits. Manufacturers 
of aerospace vehicles are constrained to using certain types of primers 
and topcoats based on the market segment for which the coating is 
intended (i.e., military original equipment manufacturer (OEM), 
military rework, commercial OEM or commercial rework) and the unique 
circumstances and design considerations within each market segment. In 
addition to being regulated by the Aerospace NESHAP, aerospace vehicle 
manufacturing and rework operations are also regulated by the Federal 
Aviation Administration (FAA), the Department of Defense and specific 
customer requirements. As outlined in the EPA's 1998 promulgation of 
amendments to the Aerospace NESHAP,\33\ affected sources must comply 
with FAA Airworthiness Directives (AD) that can potentially require the 
use of chemicals containing HAP, and affected sources may have to 
obtain alternative means of compliance for AD to allow for the 
substitution of non-HAP materials. These multiple regulations can 
result in lengthy processes for qualifying new paint systems.
---------------------------------------------------------------------------

    \33\ 63 FR 46525, September 1, 1998.
---------------------------------------------------------------------------

    Based on a finding of no new developments in practices, processes 
and control technologies in the technology review for primer and 
topcoat application operations, we are not proposing to revise the 
Aerospace NESHAP HAP and VOC content limit requirements for primer and 
topcoat application operations pursuant to CAA section 112(d)(6). For 
further discussion of the technology review results, refer to the 
memorandum, Technology Review for Primer and Topcoat Application 
Operations in the Aerospace Source Category, January 2015, available in 
the docket for this action.
2. Chemical Milling Maskant Application Operations
    In the process of chemical milling, an etchant solution is used to 
chemically reduce the thickness of selected areas of metal parts. The 
process is typically used when the size or shape of the part precludes 
mechanical milling or when chemical milling is advantageous due to 
shorter processing time or its batch capability. Before chemical 
milling, a maskant is applied to the part, allowed to cure and is then 
removed from selected areas of the part where metal is to be removed by 
the etchant. The maskant remaining on the part protects those areas 
from the etchant. Maskants are applied by brushing, dipping, spraying 
or flow coating. Organic HAP emissions occur through evaporation of the 
solvent in the maskant, typically toluene, xylene or perchloroethylene, 
as the maskant is applied and while it cures.
    There are two subcategories of chemical milling maskants in the 
Aerospace NESHAP. Type I maskants are used with chemical milling 
etchants that contain dissolved sulfur and no amines, and Type II 
maskants are used with etchants that are strong sodium hydroxide 
solutions containing amines. The Aerospace NESHAP requires the 
following organic HAP and VOC content limits for uncontrolled chemical 
milling maskants (40 CFR 63.747(c)):
     Type I: 5.2 pounds organic HAP per gallon (622 g/L) less 
water, as applied.
     Type II: 1.3 pounds of organic HAP per gallon (160 g/L) 
less water, as applied.
    These requirements do not apply to touch-up of scratched surfaces 
or damaged maskant and touch-up of trimmed edges. Alternatively, a 
control system can be used to capture and control emissions from the 
maskant application operation. The system must achieve an overall 
control efficiency of 81 percent (40 CFR 63.747(d)).
    Based on the technology review for chemical milling maskants, we 
did not identify any add-on control technologies, other equipment or 
work practices and procedures that had not previously been considered 
during development of the Aerospace NESHAP. Additionally, we did not 
identify any improvements that could be transferred to this source 
category. In our search of the RBLC, we also did not find any more 
stringent requirements. We did find that some California air quality 
management districts require more stringent VOC content limits than 
those in the Aerospace NESHAP and have higher overall minimum control 
requirements for the use of add-on control technology.

[[Page 8418]]

However, the EPA did not find any chemical milling maskant application 
operations located in these two districts that are subject to these 
more stringent limits.
    Based on a finding of no new developments in practices, processes 
and control technologies in this technology review, we are not 
proposing revisions to the Aerospace NESHAP for chemical milling 
maskant application operations pursuant to CAA section 112(d)(6). Refer 
to the memorandum, Technology Review for Chemical Milling Maskant 
Application Operations in the Aerospace Source Category, January 2015, 
available in the docket for this action, for more a more detailed 
description of the technology review results.
3. Cleaning Operations
    At Aerospace Manufacturing and Rework Facilities, cleaning 
operations are used at essentially every processing step of aerospace 
surface coating, from preparing surfaces to be coated to cleaning the 
coating application equipment. The cleaning operations regulated by the 
current Aerospace NESHAP include hand-wipe cleaning, spray gun cleaning 
and flush cleaning, as well as housekeeping measures for storage, 
handling and transfer of cleaning solvents and solvent-laden materials.
    The liquid cleaning solutions used in cleaning operations for the 
aerospace industry contain organic solvents, and some of these organic 
solvents are HAP. Organic HAP emissions from the cleaning operations 
are often fugitive in nature, resulting from the evaporation of the 
volatile portion of the cleaning solvent in large open areas, such as 
hangars. They may also be emitted from stacks when the solvents are 
used in partially or fully enclosed spray booths that are ventilated 
through stacks.
    The current Aerospace NESHAP requires that hand-wipe and flush 
cleaning solvents meet certain composition requirements, or that the 
cleaning solvents have a composite vapor pressure of no more than 45 mm 
Hg (24.1 inches water) (40 CFR 63.744(b) and (d)). The NESHAP specifies 
work practice standards for spray gun cleaning (e.g., cleaning a spray 
gun in an enclosed gun cleaning system) and flush cleaning operations 
(e.g., for flush cleaning events, empty used cleaning solvent into an 
enclosed container) (40 CFR 63.744(c) and (d)). Work practice measures 
are also specified for the storage and handling of solvents and 
solvent-laden materials (e.g., solvent-laden cloth, paper or other 
absorbent materials) (40 CFR 63.744(a)).
    Based on the technology review for cleaning operations, we did not 
identify any practices, processes or control technologies beyond those 
already required by the Aerospace NESHAP that could be transferred to 
the source category. A brief summary of the EPA's findings in 
conducting its RTR review of cleaning operations follows. For a 
detailed discussion of the EPA's findings, refer to the memorandum, 
Technology Review for Cleaning Operations in the Aerospace Source 
Category, January 2015, available in the docket for this action.
    In the technology review, we did not identify any improvements in 
add-on control technologies, other equipment or work practices and 
procedures since promulgation of the Aerospace NESHAP. The EPA 
identified one aerospace manufacturing and rework facility that routes 
the air flow from a spray booth to a carbon adsorption control device 
when performing spray gun cleaning and residual spray gun hand-wipe 
cleaning. We found that this was the same spray booth in which surface 
coating is performed, and it is not a spray booth dedicated to spray 
gun cleaning. Based on the results of the responses to the EPA's 2011 
information collection survey for other facilities, the EPA concluded 
that this practice could not be applied to the source category without 
impacting facility operations. First, very few facilities have carbon 
adsorbers controlling emissions from spray booths. Second, it is not 
always practical to move the spray gun cleaning operations into a spray 
booth without affecting the surface coating operations in that spray 
booth because of space limitations within the booth.
    The EPA also identified one aerospace manufacturing and rework 
facility that, for certain cleaning operations, uses a non-HAP solvent 
blend that has a vapor pressure of 36 mm Hg for certain cleaning 
operations; the facility does not use this solvent for all cleaning 
operations. The use of non-HAP cleaning solvent is already a compliance 
option that was considered in the development of the Aerospace NESHAP 
and is included in 40 CFR 63.744.
    Based on a finding of no new developments in practices, processes 
and control technologies in the technology review, we are not proposing 
any revisions to the Aerospace NESHAP standard requirements for 
cleaning operations pursuant to CAA section 112(d)(6). For further 
discussion of the technology review results, refer to the memorandum, 
Technology Review for Cleaning Operations in the Aerospace Source 
Category, January 2015, available in the docket for this action.
4. Chemical and Dry Media Blasting Depainting Operations
    At Aerospace Manufacturing and Rework Facilities, chemical and dry 
media blasting depainting operations remove unwanted or old surface 
coatings (e.g., primers, topcoats and specialty coatings) to prepare 
the surface for painting. As defined in the Aerospace NESHAP, a 
depainting operation means the use of a chemical agent, media blasting 
or any other technique to remove permanent coatings from the outer 
surface of an aerospace vehicle or components, excluding hand and 
mechanical sanding or other non-chemical removal processes that do not 
involve blast media or other mechanisms that would result in airborne 
particle movement at high velocity. The depainting operation includes 
washing of the aerospace vehicle or component to remove residual 
stripper, media or coating residue. Depainting is most often done in 
the rework of existing aircraft, but may also be done in limited 
circumstances in the manufacture of new aircraft.
    The liquid chemical agents (i.e., strippers) used to remove 
permanent coatings in the aerospace industry contain organic solvents. 
Organic HAP emissions from strippers occur from the evaporation of the 
chemical stripper during mixing, application and possibly during 
washing of the vehicle or component to remove residual stripper. The 
organic emissions from depainting operations that occur within a booth 
or hangar are typically captured and exhausted through a stack, 
although some emissions may be fugitive in nature (e.g., open 
containers of stripper).
    Inorganic HAP, typically metal compounds (e.g., compounds of lead, 
chromium or cadmium), can be emitted during dry media blasting if these 
compounds are present in the paint layer that is being removed. These 
inorganic HAP would be emitted as particulate matter as the dry media 
blasting removes the existing coating through abrasion.
    The Aerospace NESHAP restricts facilities to using organic HAP-
containing chemical strippers for only spot stripping and decal 
removal. The amount of stripper used for spot stripping and decal 
removal is limited to no more than 26 gallons of HAP-containing 
chemical stripper (or alternatively 190 pounds of organic HAP) for each 
commercial aircraft, and 50 gallons (or 365 pounds of organic HAP) for 
each military aircraft. As an alternative, facilities may use controls 
for organic HAP emissions from

[[Page 8419]]

chemical depainting, and emissions must be reduced by 81 percent for 
controls installed before the effective date, and by 95 percent for 
controls installed on or after the effective date (40 CFR 63.746(b)(1) 
through (3) and (c)).
    For non-chemical depainting operations that generate inorganic HAP 
emissions from dry media blasting, the operation must be performed in 
an enclosed area or in a closed cycle depainting system and the air 
stream from the operation must pass through a dry filter system meeting 
a minimum efficiency specified in the rule, through a baghouse or 
through a waterwash system before being released to the atmosphere (40 
CFR 63.746(b)(4)).
    Based on the technology review for depainting operations, we did 
not identify any practices, processes or control technologies that were 
not already required by the Aerospace NESHAP or considered in its 
development, nor did we identify any improvements to those practices, 
processes or control technologies that could be transferred and applied 
to this source category. A brief summary of the EPA's findings in 
conducting the RTR review of chemical and dry media blast depainting 
operations follows. For a detailed discussion of the EPA's findings, 
refer to the memorandum, Technology Review for Depainting Operations in 
the Aerospace Source Category, January 2015, available in the docket 
for this action.
    In reviewing Washington State's records of permits for Aerospace 
Manufacturing and Rework Facilities, we identified a 2013 PSD permit 
amendment that requires the VOC vapor pressure of cleaning solvents and 
chemical strippers used in depainting operations to be less than 45 mm 
Hg. The Aerospace NESHAP does not prescribe vapor pressure limits to 
chemical depainting strippers, but instead has capture and control and 
volume usage limits for chemical depainting operations that use HAP-
containing chemical strippers. Otherwise, facilities must use non-HAP 
chemical strippers. Therefore, we believe that the Aerospace NESHAP is 
at least as stringent as the Washington State PSD permit requirements.
    Based on a finding of no new developments in practices, processes 
and control technologies in the technology review, we are not proposing 
to revise the Aerospace NESHAP standard requirements for chemical or 
dry media blast depainting operations pursuant to CAA section 
112(d)(6). For further discussion of the technology review results, 
refer to the memorandum, Technology Review for Depainting Operations in 
the Aerospace Source Category, January 2015, available in the docket 
for this action.
5. Waste Storage and Handling Operations
    At Aerospace Manufacturing and Rework Facilities, waste is produced 
primarily from cleaning, coating and depainting operations. Cleaning 
operations produce solvent-laden cloth and paper and spent solvent 
which can emit organic HAP from the evaporation of the solvents. 
Coating operations produce waste paint and waste solvent that also emit 
organic HAP through evaporation.
    Depainting operations can produce either a liquid or solid waste 
stream depending on the type of process used. Chemical depainting 
processes produce a waste sludge that consists of the stripper solution 
and paint residue. Emissions occur from the evaporation of the solvent 
from the stripper solution in the waste sludge.
    Blast depainting processes produce a solid waste stream that 
consists of paint chips and particles and spent blasting media. 
Emissions do not directly occur from this waste stream, although 
particulate emissions are generated during the blasting process.
    The requirements for waste storage and handling in the Aerospace 
NESHAP apply to each waste storage and handling operation, which is 
defined as the total of all waste handling and storage at the facility. 
In 40 CFR 63.748, the Aerospace NESHAP requires that all waste must be 
handled and transferred to or from containers, tanks, vats, vessels and 
piping systems in such a manner that spills are minimized.
    Because the EPA did not want to create possible conflicts over the 
handling of waste between the Aerospace NESHAP and regulations under 
the Resource Conservation and Recovery Act (RCRA) of 1976 (Pub. L. 94-
580), as implemented by 40 CFR parts 260 and 261, the Aerospace NESHAP 
specifically exempted wastes covered under the RCRA regulations.\34\ 
Per 40 CFR 63.741(e), all wastes that are determined to be hazardous 
wastes under RCRA as implemented by 40 CFR parts 260 and 261, and that 
are subject to RCRA requirements as implemented in 40 CFR parts 262 
through 268, are exempt from the requirements of the Aerospace NESHAP.
---------------------------------------------------------------------------

    \34\ See the preamble to the proposed rule, 59 FR 29216, June 6, 
1994.
---------------------------------------------------------------------------

    The practical effect of the provisions in 40 CFR 63.741(e) is that 
all HAP-containing wastes generated by aerospace manufacturing and 
rework operations are subject to RCRA and are exempt from the 
requirements of 40 CFR 63.748. Because all of these HAP-containing 
wastes are covered under RCRA and exempt from 40 CFR 63.748, there is 
no need to do a technology review for the standards for handling and 
storage of waste.

E. What other actions are we proposing?

    In addition to the proposed actions described above, we are 
proposing additional revisions. As stated previously in this preamble, 
the United States Court of Appeals for the District of Columbia Circuit 
found that the EPA had erred in establishing emissions standards for 
sources of HAP in the NESHAP for Brick and Structural Clay Products 
Manufacturing and Clay Ceramics Manufacturing, 67 FR 26690 (May 16, 
2003), and consequently vacated the rules.\35\ Among other things, the 
court found EPA erred by failing to regulate processes that emitted 
HAP, in some instances by establishing a MACT floor of ``no control.'' 
In this action we are proposing to correct the same error in the 
Aerospace NESHAP by proposing to remove the exemption for specialty 
coatings found at 40 CFR 63.741(f) and instead add limits for specialty 
coatings (including adhesives, adhesive bonding primers and sealants).
---------------------------------------------------------------------------

    \35\ Sierra Club v. EPA, 479 F. 3d 875 (D.C. Cir. March 13, 
2007).
---------------------------------------------------------------------------

1. Specialty Coating Application
    At Aerospace Manufacturing and Rework Facilities, specialty 
coatings are those coatings that have additional performance criteria 
for specific applications that are beyond the criteria for primers, 
topcoats and self-priming topcoats, although specialty coatings may 
still meet the definition of a primer or topcoat. These additional 
performance criteria may include, for example, temperature or fire 
resistance, substrate compatibility, antireflection, temporary 
protection or marking, sealant properties, adhesive properties, 
electrical insulation, lubrication or enhanced corrosion protection (40 
CFR 63.742).
    Specialty coatings contain a mixture of organic solvents and/or 
inorganic HAP. The organic HAP emissions from the application of 
specialty coatings occur from the evaporation of organic solvents 
during mixing, application and drying. Emissions of inorganic HAP from 
spray-applied coating operations, typically metal compounds (e.g., 
chromium, cadmium compounds), occur when particles do not adhere to the 
surface being coated (i.e.,

[[Page 8420]]

overspray). The organic and inorganic emissions from coating 
application operations occur in large open areas, such as hangars or 
partially or fully enclosed spaces, such as within spray booths.
    The current Aerospace NESHAP explicitly excludes specialty coatings 
from meeting any control requirements, as specified in 40 CFR 63.741(f) 
and in 40 CFR 63.742 (i.e., the definitions for ``exterior primer,'' 
``primer,'' and ``topcoat''). Appendix A of the Aerospace NESHAP 
defines 59 separate categories of specialty coatings.
    Although the EPA did not include emission limitations for specialty 
coatings in the Aerospace NESHAP finalized in 1995 or in any subsequent 
amendments, the EPA included VOC content limits for the 59 categories 
of specialty coatings in the 1997 Aerospace CTG. The Aerospace CTG is 
intended to provide state and local air pollution control authorities 
with an information base, recommended emissions limitations and 
monitoring, recordkeeping and reporting requirements for proceeding 
with their analyses of reasonably available control technology (RACT) 
for their own regulations to reduce VOC emissions from aerospace 
surface coating operations. The Aerospace CTG includes presumptive VOC 
limits for specialty coating operations that are based on a review of 
the contemporary knowledge and data concerning the technology, impacts 
and costs associated with various emission control techniques. During 
their development, the specialty coating categories and VOC limits in 
the CTG were also subject to a period of public comment and review, and 
the final CTG categories and VOC limits were revised after proposal to 
reflect the EPA's analysis of those comments on the proposed CTG.
    In this action, we are proposing to establish standards for 
specialty coatings. Based on a MACT analysis for specialty coatings, we 
are proposing to require aerospace manufacturing and rework specialty 
coating application operations to achieve organic HAP content limits 
that are equivalent to the VOC content limits for specialty coatings 
included in the Aerospace CTG. As discussed previously in section 
IV.E.1 of this preamble, the Aerospace CTG may be adopted by state and 
local agencies in nonattainment areas to assist them in meeting their 
state implementation plan requirements. Of the 109 facilities that 
reported the use of specialty coatings, 35 are in nonattainment areas 
and likely currently complying with the specialty coating limits in the 
Aerospace CTG. The remaining facilities would need to take action to 
comply with the specialty coating application operations limits.
    In the MACT analysis for specialty coatings, the EPA considered 
data provided in response to a comprehensive information collection 
request (ICR) sent out in February 2011 and consulted the EPA's RACT/
BACT/LAER Clearinghouse, the California Statewide Best Available 
Control Technology (BACT) Clearinghouse and regional and state 
regulations for sources of data on control technologies and 
limitations. We reviewed state rules to compare the VOC limits in those 
rules to the VOC limits in the Aerospace CTG. This review of state 
rules was in addition to a review of the database of responses to the 
2011 ICR and the RBLC for information on add-on control technology or 
other equipment, work practices and procedures and process changes or 
pollution prevention alternatives not identified and considered during 
development of the Aerospace CTG, or improvements in the same since the 
CTG development. A brief summary of the EPA's findings in conducting 
its MACT analysis of specialty coating application operations follows. 
For a detailed discussion of the EPA's findings, refer to the 
memorandum, Maximum Achievable Control Technology for Specialty Coating 
Operations in the Aerospace Source Category, January 2015, available in 
the docket for this action.
    For specialty coatings, where there were sufficient data, the EPA 
compared the emissions for the best performing coatings with the 
Aerospace CTG limits. The results of this comparison showed that the 
CTG VOC limits were equivalent in performance to the best performing 
specialty coating. Therefore, we determined that the current Aerospace 
CTG limits represent MACT for specialty coatings.
    Based on the results of the MACT analysis, we determined that the 
VOC limits in the Aerospace CTG for specialty coatings are currently 
being achieved by about half of all operating sources subject to the 
Aerospace NESHAP. The facilities complying with the CTG limits for 
specialty coatings are located in ozone non-attainment areas where 
state VOC rules have been developed based on the Aerospace CTG. From 
our review of industry responses to the 2011 ICR, we determined that 
some facilities complying with these state VOC limits employ use of 
add-on control devices to reduce organic HAP emissions (i.e., thermal 
oxidizers and carbon adsorbers); however, these add-on controls are not 
widely used in the source category. Other facilities achieve equivalent 
emission reductions without add-on controls by using coatings that meet 
the VOC content limits.
    Based on our review of state and regional regulations for specialty 
coating operations in the aerospace industry, we identified several 
cases in which limits are specified for certain specialty coating 
categories that are lower than the VOC content limits for the same 
specialty coating categories in the Aerospace CTG. These differences 
generally affect about one-quarter of the specialty coating categories 
(although each state or regional regulation may differ from the CTG in 
only a handful of categories), and the limits differ by less than 200 
grams VOC per liter of coating. However, these state and regional rules 
and the Aerospace CTG differ in certain ways, such that the lower VOC 
limits in the state and regional rules do not represent a more 
stringent limit as compared to the Aerospace CTG.
    First, in many cases where a state rule has a lower VOC limit than 
the CTG, the state rule has also added coating categories with VOC 
limits equal to or higher than the CTG limits. For example, one state 
rule has a lower limit for fuel tank coatings, but has an additional 
category for ``rapid cure'' fuel tank coatings that is the same as the 
CTG VOC limit.
    Second, not all categories of specialty coatings are used at all 
Aerospace Manufacturing and Rework Facilities. For the specialty 
categories with more stringent VOC limits, the EPA does not have data 
to confirm that facilities exist in those jurisdictions that are using 
those coatings and actually have to comply with the more stringent VOC 
limits. These data on facilities actually using coatings subject to 
these more stringent limits would be needed to confirm that these more 
stringent limits constitute the MACT floor according to section 
112(d)(3) of the CAA.
    Finally, many of the areas with more stringent VOC limits than in 
the CTG have climates that are warmer and drier than in most other 
parts of the United States, and this type of climate is more conducive 
to the use of low-VOC coatings because it helps promote expeditious 
curing of the coatings under ambient conditions. In cooler and more 
humid areas, the coatings require the use of a solvent carrier and/or 
thermal curing. The Aerospace NESHAP and CTG, on the other hand, must 
establish HAP and VOC limits that are applicable across the United 
States. It is not practical to establish MACT limits for coatings based 
on regional climate differences for this source category.

[[Page 8421]]

    Based on the issues noted above, the EPA concludes that the noted 
differences between the state and regional rules and the Aerospace CTG 
limits do not constitute more stringent limits compared to those in the 
Aerospace CTG. The EPA does not have sufficient data to determine 
whether these differences in VOC limits, compared to the limits in the 
Aerospace CTG, actually constitute MACT. Therefore, the EPA is 
specifically soliciting comment and additional data on the differences 
noted between state and regional rules and the aerospace CTG.
    Based on its analysis, the EPA is proposing the MACT floor for 
specialty coatings to be organic HAP content limits equal to the VOC 
limits specified in the Aerospace CTG for specialty coatings. 
Additionally, the low-volume exemption provisions in the current 
Aerospace NESHAP for primers, topcoats and chemical milling maskants 
may be used for specialty coatings. The EPA has not identified any 
options more stringent than the MACT floor as documented in the review 
of specialty coatings discussed earlier in this section, so the 
proposed organic HAP content limits are equal to the MACT floor VOC 
content limits. The EPA is proposing this MACT floor based on the fact 
that these VOC limits are currently being achieved by at least 12 
percent of the operating facilities in a total population of 109 
operating aerospace and rework facilities that reported using specialty 
coatings in the 2011 ICR. For more information on the MACT floor 
analysis, please refer to the memorandum, Maximum Achievable Control 
Technology for Specialty Coating Operations in the Aerospace Source 
Category, January 2015, available in the docket for this action.
    In reviewing the state and district VOC rules, the EPA determined 
that the aerospace surface coating rules in many of the California 
district rules, in addition to the requirement to meet VOC limits, 
require that all spray-applied coating operations use high-efficiency 
application equipment (i.e., HVLP, electrostatic spray or an 
equivalent). This requirement is more stringent than the model rule 
found in the Aerospace CTG, which exempts specialty coatings from the 
requirement to use high-efficiency application equipment. The 
California rules examined by the EPA require the use of high-efficiency 
application equipment for all spray applied coatings, unless an add-on 
control system was used, or certain other exemptions apply. Other state 
rules that follow the CTG require high-efficiency application methods 
only for primer and topcoat application operations. The facilities 
located in California that are required to use high-efficiency 
application equipment for specialty coatings constitute the MACT floor 
for the application of these coatings. This determination is based on 
the fact that at least 11 facilities in California's air pollution 
control districts are currently subject to district rules that require 
high-efficiency application equipment for all coating operations, 
including specialty coatings. Therefore, the EPA is proposing that 
specialty coatings be subject to the same application requirements in 
40 CFR 63.745(f) as primers and topcoats. Compared to conventional 
spray application methods, high-efficiency application methods, such as 
HVLP spray guns or electrostatic deposition, can achieve HAP and VOC 
emission reductions because of reduced coating consumption that results 
from reduced coating overspray. The EPA has not identified any control 
options more stringent than the use of high-efficiency application 
methods for spray-applied coating operations.
    In our review of the RBLC, we did not identify any control options 
for aerospace specialty surface coating operations that were not 
already reflected in the VOC content limits in the Aerospace CTG. 
However, we identified one facility in the state of Washington for 
which a BACT analysis was completed in September 2014, for constructing 
new buildings needed for producing new models of large commercial 
airplanes, including the building and surface coating of composite 
aircraft wings. The BACT analysis described the facility as currently 
using HVLP spraying and electrostatic airless and modified high-
efficiency air-assisted airless spray equipment in all spray applied 
surface coating operations. The BACT analysis concluded that there were 
no demonstrations of add-on controls at facilities performing surface 
coating comparable to large commercial aircraft wing components.
    In our review of Washington State's record of permits, we 
determined that the current PSD permit for this facility identified 
BACT for VOC from coating operations to be the equivalent of complying 
with ``all applicable VOC emission standards of the Aerospace NESHAP.'' 
The PSD permit for the facility did not consider add-on control 
technologies to be BACT after taking into account energy, environmental 
and economic impacts. Based on this information from the RBLC and the 
Washington State BACT analysis, we determined that add-on control 
techniques would not be MACT for specialty coating application 
operations for the aerospace industry.
    Instead, MACT is being proposed as the use of low-HAP coatings 
(with HAP content limits equal to the VOC content limits in the 
Aerospace CTG) and high-efficiency application methods for spray-
applied coating operations. As the EPA did with primers and top coats 
in the current NESHAP, the EPA is proposing to use VOC limits that are 
currently in effect as the basis for proposed organic HAP limits.
    The EPA is also proposing to establish MACT to limit emissions of 
inorganic HAP from spray-applied specialty coatings that contain 
inorganic HAP. The predominant method used to control inorganic HAP 
emissions from all spray-applied coating operations (including 
specialty coatings) is the use of a spray booth with a particulate 
filter, which generally achieves a high (i.e., greater than 99 percent) 
control efficiency. The Aerospace NESHAP currently requires the use of 
spray booths with filters meeting minimum efficiency requirements for 
the spray application of primers and topcoats that contain inorganic 
HAP. Based on the results of the 2011 ICR, the EPA has determined that 
the vast majority of spray-applied specialty coatings are currently 
applied in spray booths. It is likely that these specialty coatings are 
applied in the same spray booths as primers and topcoats, or at least 
in spray booths that are very similar to those used for primer and 
topcoat operations. Therefore, the same inorganic HAP emission 
limitations that are applied to primer and topcoat operations should 
also be applicable to specialty coating operations, and the EPA is 
proposing to extend these limitations to specialty coating operations. 
The EPA has not identified any control options more stringent than the 
use of spray booths with high-efficiency filters to control inorganic 
HAP emissions from spray-applied coating operations.
    In summary, the EPA is proposing to add a requirement to the 
Aerospace NESHAP that Aerospace Manufacturing and Rework Facilities 
comply with organic HAP or VOC content limits for specialty coatings 
that are equal to the VOC content limits specified in the Aerospace 
CTG. The EPA is also proposing that specialty coating application 
operations be subject to the same application equipment requirements in 
40 CFR 63.745(f), and the standards for inorganic HAP emissions in 40 
CFR 63.745(g) that apply to primer and topcoat application operations. 
We request comment on our analysis and supporting info on any

[[Page 8422]]

other practices that may be used to limit emissions from specialty 
coatings.
    The EPA believes that the proposed HAP and VOC content limits for 
specialty coatings are achievable because they are based on the VOC 
content limits in the Aerospace CTG, which have been adopted in many 
state and local VOC rules. In the development of these proposed 
amendments, the EPA made repeated efforts to reach out to and solicit 
input from aerospace manufacturers on the coating performance and 
reformulation challenges, if any, presented by complying with specialty 
coating limits based on the current CTG. However, the information 
presented so far has been only anecdotal, and not for the full range of 
specialty coating categories in the CTG.
    Therefore, the EPA is specifically soliciting comment and 
additional data on any changes needed to the definitions of specialty 
coating categories and the proposed organic HAP and VOC limits. The EPA 
will consider comments on changes to the definitions of specialty 
coating categories that may be needed to clarify the scope of each of 
the individual specialized coating categories, based on industry 
experience, including complying with those categories in rules derived 
from the Aerospace CTG. The EPA will consider data and information on 
specific cases (not just general examples) of specialty coatings that 
could not meet the current definitions of the specialty coating 
categories or the proposed organic HAP or VOC content limits for those 
categories. Please provide with your comments information on the 
following: The annual volume of the coating used, the container size, 
the container type, the military specification or FAA AD that applies, 
the specialty category that applies, documentation of the organic HAP 
or VOC content of the coating and suggested changes to category 
definitions (if applicable and feasible) that would include the coating 
in a more appropriate category with a higher HAP or VOC limit. The EPA 
will consider any submitted data that supports a comment that a 
specific coating cannot meet the proposed organic HAP or VOC content 
limit for a particular specialty coating category.
    The estimated costs, emission reductions, other (non-air) 
environmental impacts and energy impacts associated with the proposed 
regulation of specialty coatings are presented in section V of this 
preamble.
2. Electronic Reporting Requirements
    In this proposal, the EPA is describing a process to increase the 
ease and efficiency of performance test data submittal while improving 
data accessibility. Specifically, the EPA is proposing that owners and 
operators of Aerospace Manufacturing and Rework Facilities submit 
electronic copies of required performance test and performance 
evaluation reports by direct computer-to-computer electronic transfer 
using EPA-provided software. The direct computer-to-computer electronic 
transfer is accomplished through the EPA's Central Data Exchange (CDX) 
using the Compliance and Emissions Data Reporting Interface (CEDRI). 
The CDX is the EPA's portal for submittal of electronic data. The EPA-
provided software is called the Electronic Reporting Tool (ERT), which 
is used to generate electronic reports of performance tests and 
evaluations. The ERT generates an electronic report package which will 
be submitted using the CEDRI. The submitted report package will be 
stored in the CDX archive (the official copy of record) and the EPA's 
public database called WebFIRE. The WebFIRE database was constructed to 
store performance test data for use in developing emissions factors. 
All stakeholders would have access to all reports and data in WebFIRE 
and accessing these reports and data will be very straightforward and 
easy (see the WebFIRE Report Search and Retrieval link at https://cfpub.epa.gov/webfire/index.cfm?action=fire.searchERTSubmission). A 
description of the WebFIRE database is available at https://cfpub.epa.gov/oarweb/index.cfm?action=fire.main. A description of the 
ERT and instructions for using ERT can be found at https://www.epa.gov/ttn/chief/ert/ert_tool.html. CEDRI can be accessed through the CDX Web 
site (www.epa.gov/cdx).
    The proposal to submit performance test data electronically to the 
EPA would apply only to those performance tests conducted using test 
methods that will be supported by the ERT. The ERT contains a specific 
electronic data entry form for most of the commonly used EPA reference 
methods. A listing of the pollutants and test methods supported by the 
ERT is available at https://www.epa.gov/ttn/chief/ert/. We 
believe that industry would benefit from this proposed approach to 
electronic data submittal. Specifically, by using this approach, 
industry would save time in the performance test submittal process. 
Additionally, the standardized format that the ERT uses allows sources 
to create a more complete test report resulting in less potential 
failure to include all data elements required to be submitted. Also 
through this proposal, industry may only need to submit a report once 
to meet the requirements of the applicable subpart because stakeholders 
can readily access these reports from the WebFIRE database. This also 
would benefit industry by cutting back on recordkeeping costs as the 
performance test reports that are submitted to the EPA using CEDRI are 
no longer required to be retained in hard copy, thereby reducing staff 
time needed to coordinate these records. Another benefit to industry is 
that, because the EPA would already have performance test data in hand, 
industry would be subject to fewer or less substantial data collection 
requests from EPA in conjunction with required future residual risk 
assessments or technology reviews. This would result in a decrease in 
industry staff time needed to respond to data collection requests.
    State, local and tribal air pollution control agencies (S/L/Ts) may 
also benefit from having electronic versions of the reports they are 
now receiving. For example, S/L/Ts may be able to conduct a more 
streamlined and accurate review of electronic data submitted to them. 
The ERT would allow for an electronic review process, rather than a 
manual data assessment, which will make review and evaluation of the 
source provided data and calculations easier and more efficient. In 
addition, the public will benefit from electronic reporting of 
emissions data because the electronic data will be easier for the 
public to access. How the air emissions data are collected, accessed 
and reviewed will be more transparent for all stakeholders.
    Further, the EPA must have performance test data to conduct 
effective reviews of CAA sections 112 and 129 standards, as well as for 
many other purposes including compliance determinations, emissions 
factor development and annual emissions rate determinations. In 
conducting these required reviews, the EPA has found it ineffective and 
time consuming, not only for the EPA, but also for regulatory agencies 
and source owners and operators, to locate, collect and submit 
performance test data because of varied locations for data storage and 
varied data storage methods. In recent years, though, stack testing 
firms have typically collected performance test data in electronic 
format, making it possible to move to an electronic data submittal 
system that would increase the ease and efficiency of data submittal 
and improve data accessibility.

[[Page 8423]]

    One major advantage of the proposed submittal of performance test 
data through the ERT is a standardized method to compile and store much 
of the documentation required to be reported by this rule. Another 
advantage is that the ERT clearly states what testing information would 
be required. Another important proposed benefit of submitting these 
data to the EPA at the time the source test is conducted is that it 
should substantially reduce the effort involved in data collection 
activities in the future. When the EPA has performance test data in 
hand, the EPA will be able to conduct fewer or less substantial data 
collection requests in conjunction with future required residual risk 
assessments or technology reviews. This would result in a reduced 
burden on both affected facilities (in terms of reduced staff time to 
respond to data collection requests) and the EPA (in terms of preparing 
and distributing data collection requests and assessing the results).
    Finally, another benefit of the proposed data submittal to WebFIRE 
electronically is that these data would greatly improve the overall 
quality of existing and new emissions factors by supplementing the pool 
of emissions test data for establishing emissions factors and by 
ensuring that the factors are more representative of current industry 
operational procedures. A common complaint heard from industry and 
regulators is that emissions factors are outdated or not representative 
of a particular source category. With timely receipt and incorporation 
of data from most performance tests, the EPA would be able to ensure 
that emissions factors, when updated, represent the most current range 
of operational practices.
    In summary, in addition to supporting regulation development, 
control strategy development and other air pollution control 
activities, having an electronic database populated with performance 
test data would save industry, state, local, tribal agencies and the 
EPA significant time, money and effort while also improving the quality 
of emissions inventories and, as a result, air quality regulations.
3. Startup, Shutdown and Malfunction Requirements
    In its 2008 decision in Sierra Club v. EPA, 551 F.3d 1019 (D.C. 
Cir. 2008), cert. denied, 130 S. Ct. 1735 (U.S. 2010), the United 
States Court of Appeals for the District of Columbia Circuit vacated 
portions of two provisions in the EPA's CAA section 112 regulations 
governing the emissions of HAP during periods of SSM. Specifically, the 
court vacated the SSM exemption contained in 40 CFR 63.6(f)(1) and 
(h)(1), holding that under section 302(k) of the CAA, emissions 
standards or limitations must be continuous in nature and that the SSM 
exemption violates the CAA's requirement that some section 112 
standards apply continuously.
    We are proposing the elimination of the SSM exemption in this rule. 
Consistent with Sierra Club v. EPA, we are proposing changes so that 
standards in this rule would apply at all times. We are also proposing 
several revisions to Table 1 to subpart GG of Part 63 (the General 
Provisions Applicability Table, hereafter referred to as the ``General 
Provisions table'') as explained in more detail below. For example, we 
are proposing to eliminate the incorporation of the General Provisions' 
requirement that the source develop an SSM plan. We also are proposing 
to eliminate and revise certain recordkeeping and reporting 
requirements related to the SSM exemption as further described below.
    The EPA has attempted to ensure that the provisions we are 
proposing to eliminate are inappropriate, unnecessary or redundant in 
the absence of the SSM exemption. We are specifically seeking comment 
on whether we have successfully done so.
    In proposing the standards in this rule, the EPA has taken into 
account startup and shutdown periods and, for the reasons explained 
below, has not proposed alternate standards for those periods.
    Periods of startup, normal operations and shutdown are all 
predictable and routine aspects of a source's operations. Malfunctions, 
in contrast, are neither predictable nor routine. Instead they are, by 
definition sudden, infrequent and not reasonably preventable failures 
of emissions control, process or monitoring equipment. The EPA 
interprets CAA section 112 as not requiring emissions that occur during 
periods of malfunction to be factored into development of CAA section 
112 standards. Under section 112, emissions standards for new sources 
must be no less stringent than the level ``achieved'' by the best 
controlled similar source and, for existing sources, generally must be 
no less stringent than the average emission limitation ``achieved'' by 
the best performing 12 percent of sources in the category. There is 
nothing in section 112 that directs the agency to consider malfunctions 
in determining the level ``achieved'' by the best performing sources 
when setting emission standards. As the D.C. Circuit has recognized, 
the phrase ``average emissions limitation achieved by the best 
performing 12 percent of'' sources ``says nothing about how the 
performance of the best units is to be calculated.'' Nat'l Ass'n of 
Clean Water Agencies v. EPA, 734 F.3d 1115, 1141 (D.C. Cir. 2013). 
While the EPA accounts for variability in setting emissions standards, 
nothing in CAA section 112 requires the agency to consider malfunctions 
as part of that analysis. A malfunction should not be treated in the 
same manner as the type of variation in performance that occurs during 
routine operations of a source. A malfunction is a failure of the 
source to perform in a ``normal or usual manner'' and no statutory 
language compels the EPA to consider such events in setting CAA section 
112 standards.
    Further, accounting for malfunctions in setting emission standards 
would be difficult, if not impossible, given the myriad different types 
of malfunctions that can occur across all sources in the category and 
given the difficulties associated with predicting or accounting for the 
frequency, degree and duration of various malfunctions that might 
occur. As a result, the performance of units that are malfunctioning is 
not ``reasonably'' foreseeable. See, e.g. Sierra Club v. EPA, 167 F.3d 
658, 662 (D.C. Cir. 1999) (``The EPA typically has wide latitude in 
determining the extent of data-gathering necessary to solve a problem. 
We generally defer to an agency's decision to proceed on the basis of 
imperfect scientific information, rather than to `invest the resources 
to conduct the perfect study.' '') See also, Weyerhaeuser v. Costle, 
590 F.2d 1011, 1058 (D.C. Cir. 1978) (``In the nature of things, no 
general limit, individual permit, or even any upset provision can 
anticipate all upset situations. After a certain point, the 
transgression of regulatory limits caused by `uncontrollable acts of 
third parties,' such as strikes, sabotage, operator intoxication or 
insanity and a variety of other eventualities, must be a matter for the 
administrative exercise of case-by-case enforcement discretion, not for 
specification in advance by regulation.''). In addition, emissions 
during a malfunction event can be significantly higher than emissions 
at any other time of source operation. For example, if an air pollution 
control device with 99-percent removal goes off-line as a result of a 
malfunction (as might happen if, for example, the bags in a baghouse 
catch fire) and the emission unit is a steady-state type unit that 
would take days to shut down, the source would go from 99-percent 
control to zero control until the control device was repaired. The 
source's emissions during the malfunction

[[Page 8424]]

would be 100 times higher than during normal operations and the 
emissions over a 4-day malfunction period would exceed the annual 
emissions of the source during normal operations. As this example 
illustrates, accounting for malfunctions could lead to standards that 
are not reflective of (and significantly less stringent than) levels 
that are achieved by a well-performing non-malfunctioning source. It is 
reasonable to interpret CAA section 112 to avoid such a result. The 
EPA's approach to malfunctions is consistent with CAA section 112 and 
is a reasonable interpretation of the statute.
    In the event that a source fails to comply with the applicable CAA 
section 112 standards as a result of a malfunction event, the EPA would 
determine an appropriate response based on, among other things, the 
good faith efforts of the source to minimize emissions during 
malfunction periods, including preventative and corrective actions, as 
well as root cause analyses to ascertain and rectify excess emissions. 
The EPA would also consider whether the source's failure to comply with 
the CAA section 112 standard was, in fact, sudden, infrequent, not 
reasonably preventable and was not instead caused in part by poor 
maintenance or careless operation.
    If the EPA determines that an enforcement action against a source 
for violation of an emission standard is warranted, the source can 
raise any and all defenses in that enforcement action and the federal 
district court will determine what, if any, relief is appropriate. The 
same is true for citizen enforcement actions. Similarly, the presiding 
officer in an administrative proceeding can consider any defense raised 
and determine whether administrative penalties are appropriate.
    In summary, the EPA interpretation of the CAA and, in particular, 
CAA section 112 is reasonable and encourages practices that will avoid 
malfunctions. Administrative and judicial procedures for addressing 
exceedances of the standards fully recognize that violations may occur 
despite good faith efforts to comply and can accommodate those 
situations.
    In several prior CAA section 112 rules, the EPA had included an 
affirmative defense to civil penalties for violations caused by 
malfunctions in an effort to create a system that incorporates some 
flexibility, recognizing that there is a tension, inherent in many 
types of air regulation, to ensure adequate compliance while 
simultaneously recognizing that despite the most diligent of efforts, 
emission standards may be violated under circumstances entirely beyond 
the control of the source. Although the EPA recognized that its case-
by-case enforcement discretion provides sufficient flexibility in these 
circumstances, it included the affirmative defense to provide a more 
formalized approach and more regulatory clarity. See Weyerhaeuser Co. 
v. Costle, 590 F.2d 1011, 1057-58 (D.C. Cir. 1978) (holding that an 
informal case-by-case enforcement discretion approach is adequate); but 
see Marathon Oil Co. v. EPA, 564 F.2d 1253, 1272-73 (9th Cir. 1977) 
(requiring a more formalized approach to consideration of ``upsets 
beyond the control of the permit holder''). Under the EPA's regulatory 
affirmative defense provisions, if a source could demonstrate in a 
judicial or administrative proceeding that it had met the requirements 
of the affirmative defense in the regulation, civil penalties would not 
be assessed. Recently, the United States Court of Appeals for the 
District of Columbia Circuit vacated an affirmative defense in one of 
the EPA's CAA section 112 regulations. NRDC v. EPA, 749 F.3d 1055 (D.C. 
Cir., 2014) (vacating affirmative defense provisions in CAA section 112 
rule establishing emission standards for Portland cement kilns). The 
court found that the EPA lacked authority to establish an affirmative 
defense for private civil suits and held that under the CAA, the 
authority to determine civil penalty amounts in such cases lies 
exclusively with the courts, not the EPA. Specifically, the court 
found: ``As the language of the statute makes clear, the courts 
determine, on a case-by-case basis, whether civil penalties are 
`appropriate.''' See NRDC, 2014 U.S. App. LEXIS 7281 at *21 (``[U]nder 
this statute, deciding whether penalties are `appropriate' in a given 
private civil suit is a job for the courts, not EPA.'').\36\ In light 
of NRDC, the EPA is not including a regulatory affirmative defense 
provision in the proposed rule. As explained above, if a source is 
unable to comply with emissions standards as a result of a malfunction, 
the EPA may use its case-by-case enforcement discretion to provide 
flexibility, as appropriate. Further, as the United States Court of 
Appeals for the District of Columbia Circuit recognized, in an EPA or 
citizen enforcement action, the court has the discretion to consider 
any defense raised and determine whether penalties are appropriate. Cf. 
NRDC, 2014 U.S. App. LEXIS 7281 at *24 (arguments that violation were 
caused by unavoidable technology failure can be made to the courts in 
future civil cases when the issue arises). The same is true for the 
presiding officer in EPA administrative enforcement actions.\37\
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    \36\ The court's reasoning in NRDC v. EPA focuses on civil 
judicial actions. The Court noted that ``EPA's ability to determine 
whether penalties should be assessed for Clean Air Act violations 
extends only to administrative penalties, not to civil penalties 
imposed by a court.'' Id.
    \37\ Although the NRDC v. EPA case does not address the EPA's 
authority to establish an affirmative defense to penalties that is 
available in administrative enforcement actions, the EPA is not 
including such an affirmative defense in the proposed rule. As 
explained above, such an affirmative defense is not necessary. 
Moreover, assessment of penalties for violations caused by 
malfunctions in administrative proceedings and judicial proceedings 
should be consistent. CF. CAA section 113(e) (requiring both the 
Administrator and the court to take specified criteria into account 
when assessing penalties).
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a. 40 CFR 63.743(e) General Duty
    We are proposing to revise the entry in the General Provisions 
table for 40 CFR 63.6(e)(1)(i) by changing the ``yes'' in column 2 to a 
``no.'' Section 63.6(e)(1)(i) describes the general duty to minimize 
emissions. Some of the language in that section is no longer necessary 
or appropriate in light of the elimination of the SSM exemption. We are 
proposing instead to add general duty regulatory text at 40 CFR 
63.743(e) that reflects the general duty to minimize emissions while 
eliminating the reference to periods covered by an SSM exemption. The 
current language in 40 CFR 63.6(e)(1)(i) characterizes what the general 
duty entails during periods of SSM. With the elimination of the SSM 
exemption, there is no need to differentiate between normal operations, 
startup and shutdown and malfunction events in describing the general 
duty. Therefore the language the EPA is proposing for 40 CFR 63.743(e) 
does not include that language from 40 CFR 63.6(e)(1).
    We are also proposing to revise the General Provisions table entry 
for 40 CFR 63.6(e)(1)(ii) by changing the ``yes'' in column 2 to a 
``no.'' Section 63.6(e)(1)(ii) imposes requirements that are not 
necessary with the elimination of the SSM exemption or are redundant 
with the general duty requirement being added at 40 CFR 63.743(e).
b. SSM Plan
    We are proposing to revise the General Provisions table entry for 
40 CFR 63.6(e)(3) by changing the ``yes'' in column 2 to a ``no.'' 
Generally, these paragraphs require development of an SSM plan and 
specify SSM recordkeeping and reporting requirements related to the SSM 
plan. As noted, the EPA is proposing to remove the SSM exemptions. 
Therefore, affected units will be subject to an

[[Page 8425]]

emission standard during such events. The applicability of a standard 
during such events will ensure that sources have ample incentive to 
plan for and achieve compliance and, thus, the SSM plan requirements 
are no longer necessary.
c. Compliance With Standards
    We are proposing to revise the General Provisions table entry for 
40 CFR 63.6(f)(1) by changing the ``yes'' in column 2 to a ``no.'' The 
current language of 40 CFR 63.6(f)(1) exempts sources from non-opacity 
standards during periods of SSM. As discussed above, the court in 
Sierra Club v. EPA vacated the exemptions contained in this provision 
and held that the CAA requires that some CAA section 112 standards 
apply continuously. Consistent with Sierra Club, the EPA is proposing 
to revise some standards in this rule to apply at all times.
d. 40 CFR 63.749(j) Performance Testing
    We are proposing to revise the General Provisions table entry for 
40 CFR 63.7(e)(1) by changing the ``yes'' in column 2 to a ``no.'' 
Section 63.7(e)(1) describes performance testing requirements. The EPA 
is instead proposing to add a performance testing requirement at 40 CFR 
63.749(j). The performance testing requirements we are proposing to add 
differ from the General Provisions performance testing provisions in 
several respects. The regulatory text does not include the language in 
40 CFR 63.7(e)(1) that restated the SSM exemption and language that 
precluded startup and shutdown periods from being considered 
``representative'' for purposes of performance testing. The proposed 
performance testing provisions will specify that performance testing of 
controls must be conducted during representative operating conditions 
of the applicable source, and may not take place during startup, 
shutdown or malfunction of the applicable controlled surface coating 
operations, controlled chemical milling maskant application operations 
or controlled chemical depainting operations. As in 40 CFR 63.7(e)(1), 
performance tests conducted under this subpart should not be conducted 
during malfunctions because conditions during malfunctions are often 
not representative of normal operating conditions. The EPA is proposing 
to add language that requires the owner or operator to record the 
process information that is necessary to document operating conditions 
during the test and include in such record an explanation to support 
that such conditions represent normal operation. Section 63.7(e) 
requires that the owner or operator make available to the Administrator 
such records ``as may be necessary to determine the condition of the 
performance test'' available to the Administrator upon request, but 
does not specifically require the information to be recorded. The 
regulatory text the EPA is proposing to add to this provision builds on 
that requirement and makes explicit the requirement to record the 
information.
e. Monitoring
    We are proposing to revise the General Provisions table entry for 
40 CFR 63.8(c)(1)(i) and (iii) by changing the ``yes'' in column 2 to a 
``no.'' The cross-references to the general duty and SSM plan 
requirements in those subparagraphs are not necessary in light of other 
requirements of 40 CFR 63.8 that require good air pollution control 
practices (40 CFR 63.8(c)(1)) and that set out the requirements of a 
quality control program for monitoring equipment (40 CFR 63.8(d)).
f. 40 CFR 63.752(a) Recordkeeping
    We are proposing to revise the General Provisions table entry for 
40 CFR 63.10(b)(2)(i) by changing the ``yes'' in column 2 to a ``no.'' 
Section 63.10(b)(2)(i) describes the recordkeeping requirements during 
startup and shutdown. These recording provisions are no longer 
necessary because the EPA is proposing that recordkeeping and reporting 
applicable to normal operations will apply to startup and shutdown. In 
the absence of special provisions applicable to startup and shutdown, 
such as a startup and shutdown plan, there is no reason to retain 
additional recordkeeping for startup and shutdown periods.
    We are proposing to revise the General Provisions table entry for 
40 CFR 63.10(b)(2)(ii) by changing the ``yes'' in column 2 to a ``no.'' 
Section 63.10(b)(2)(ii) describes the recordkeeping requirements during 
a malfunction. The EPA is proposing to add such requirements to 40 CFR 
63.752(a). The regulatory text we are proposing to add differs from the 
General Provisions it is replacing in that the General Provisions 
requires the creation and retention of a record of the occurrence and 
duration of each malfunction of process, air pollution control and 
monitoring equipment. The EPA is proposing that this requirement apply 
to any failure to meet an applicable standard and is requiring that the 
source record the date, time and duration of the failure rather than 
the ``occurrence.'' The EPA is also proposing to add to 40 CFR 
63.752(a) a requirement that sources keep records that include a list 
of the affected source or equipment and actions taken to minimize 
emissions, an estimate of the quantity of each regulated pollutant 
emitted over the standard for which the source failed to meet the 
standard and a description of the method used to estimate the 
emissions. Examples of such methods would include mass balance 
calculations, measurements when available or engineering judgment based 
on known process parameters (e.g., coating HAP content and application 
rate or control device efficiencies). The EPA is proposing to require 
that sources keep records of this information to ensure that there is 
adequate information to allow the EPA to determine the severity of any 
failure to meet a standard and to provide data that may document how 
the source met the general duty to minimize emissions when the source 
has failed to meet an applicable standard.
    We are proposing to revise the General Provisions table entry for 
40 CFR 63.10(b)(2)(iv) by changing the ``yes'' in column 2 to a ``no.'' 
When applicable, the provision requires sources to record actions taken 
during SSM events when actions were inconsistent with their SSM plan. 
The requirement is no longer appropriate because SSM plans will no 
longer be required. The requirement previously applicable under 40 CFR 
63.10(b)(2)(iv)(B) to record actions to minimize emissions and record 
corrective actions is now applicable by reference to 40 CFR 63.752(a).
    We are proposing to revise the General Provisions table entry for 
40 CFR 63.10(b)(2)(v) by changing the ``yes'' in column 2 to a ``no.'' 
When applicable, the provision requires sources to record actions taken 
during SSM events to show that actions taken were consistent with their 
SSM plan. The requirement is no longer appropriate because SSM plans 
will no longer be required.
g. 40 CFR 63.753 Reporting
    We are proposing to revise the General Provisions table entry for 
40 CFR 63.10(d)(5) by changing the ``yes'' in column 2 to a ``no.'' 
Section 63.10(d)(5) describes the reporting requirements for startups, 
shutdowns and malfunctions. To replace the General Provisions reporting 
requirement, the EPA is proposing to add reporting requirements to 40 
CFR 63.753(a). The replacement language added to 40 CFR 63.753(a) 
differs from the General Provisions requirement in that it eliminates 
periodic SSM reports

[[Page 8426]]

as a stand-alone report. We are proposing language that requires 
sources that fail to meet an applicable standard at any time to report 
the information concerning such events in the semi-annual reporting 
period already required under this rule. We are proposing that the 
report must contain the number, date, time, duration and the cause of 
such events (including unknown cause, if applicable), a list of the 
affected source or equipment, an estimate of the quantity of each 
regulated pollutant emitted over any emission limit and a description 
of the method used to estimate the emissions.
    Examples of such methods would include mass balance calculations, 
measurements when available or engineering judgment based on known 
process parameters (e.g., coating HAP content and application rates and 
control device efficiencies). The EPA is proposing this requirement to 
ensure that there is adequate information to determine compliance, to 
allow the EPA to determine the severity of the failure to meet an 
applicable standard and to provide data that may document how the 
source met the general duty to minimize emissions during a failure to 
meet an applicable standard.
    We would no longer require owners or operators to determine whether 
actions taken to correct a malfunction are consistent with an SSM plan, 
because plans would no longer be required. The proposed amendments 
would, therefore, eliminate the cross reference to 40 CFR 
63.10(d)(5)(i) that contains the description of the previously required 
SSM report format and submittal schedule from this section. These 
specifications would be no longer necessary because the events would be 
reported in otherwise required reports with similar format and 
submittal requirements.
    As discussed above, we are proposing to revise the General 
Provisions table entry for 40 CFR 63.10(d)(5), by changing the ``yes'' 
in column 2 to a ``no.'' Section 63.10(d)(5)(ii) describes an immediate 
report for startups, shutdown and malfunctions when a source failed to 
meet an applicable standard, but did not follow the SSM plan. We will 
no longer require owners and operators to report when actions taken 
during a startup, shutdown or malfunction were not consistent with an 
SSM plan, because plans would no longer be required to allow the EPA to 
determine the severity of the failure to meet an applicable standard 
and to provide data that may document how the source met the general 
duty to minimize emissions during a failure to meet an applicable 
standard.
4. Technical Amendments to the Aerospace NESHAP
    The EPA is also proposing the following technical corrections:
     Revising 40 CFR 63.743(a)(2) to match the section title in 
40 CFR 63.5.
     Revising 40 CFR 63.743(a)(8) to correct the reference to 
paragraph 63.6(i)(12)(iii)(B) by changing the ``(1)'' to an ``(i).''
     Revising 40 CFR 63.744(a) to correct and clarify the 
format of the reference to 40 CFR 63.744(a)(1) through (4).
     Correct the ordering of 40 CFR 63.744(a)(3) and (4); 
currently paragraph (a)(4) is printed before (a)(3).
     Correcting the paragraph numbering for 40 CFR 
63.746(b)(4)(ii)(C) by changing paragraph (C) from a lower case to 
upper case ``C.''
     Correcting the numbering of the tables in 40 CFR 63.745 to 
account for the proposed addition of Table 1 to that section to include 
specialty coating limits.
     Revising 40 CFR 63.749(d)(4) to correct the references to 
40 CFR 63.749(d)(4)(i) through (d)(4)(iv) and (e).
     Revising 40 CFR 63.750(g)(6)(i) to remove the letters 
``VR/FD'' that were inadvertently included.
5. Amendments To Simplify Recordkeeping and Reporting for Compliant 
Coatings
    The EPA is proposing to revise 40 CFR 63.750 to include alternative 
compliance demonstration provisions for all coatings subject to the 
Aerospace NESHAP (primers, topcoats, specialty coatings and chemical 
milling maskants). If the manufacturer's supplied formulation data or 
calculation of HAP and VOC content indicate that the coating meets the 
organic HAP and VOC content emission limits for its coating type, as 
specified in 40 CFR 63.745(c) and 63.747(c), then the owner or operator 
would not be required to demonstrate compliance for these coatings 
using the test method and calculations specified in 40 CFR 63.750(c), 
(e), (k) and (m) or to keep the associated records and submit the 
associated reports associated with these methods and calculations. 
Instead, the owner or operator would be able to rely on the 
manufacturers' formulation data and calculation of the HAP or VOC 
content to demonstrate compliance. However, the owner or operator would 
still be required to maintain purchase records and manufacturer's 
supplied data sheets for these compliant coatings. Owners or operators 
of facilities using these coatings would also still be required to 
handle and transfer these coatings in a manner that minimizes spills, 
apply these coatings using one or more of the specified application 
techniques and comply with inorganic HAP emission requirements.
    This change is being proposed to reduce unnecessary recordkeeping 
and avoid the need for owners or operators to perform tests to measure 
VOC and HAP content and to perform certain calculations that can be 
done by the coating manufacturer based on coating formulation data. 
When the Aerospace NESHAP was originally promulgated, the original 
compliance demonstration and recordkeeping requirements were needed 
because the product data sheets provided by coating manufacturers did 
not routinely provide VOC content in grams per liter (less water and 
exempt solvents) or HAP content in grams per liter (less water). As a 
result, it was necessary for the facilities to calculate the VOC or HAP 
content in this format to demonstrate compliance.
    Since promulgation of the Aerospace NESHAP, coating manufacturers 
now commonly provide VOC content of the coatings, in grams per liter 
(less water and exempt solvents) on the product data sheets, based on 
coating formulation. Therefore, the coating manufacturer's 
documentation can be used to demonstrate compliance, when available, in 
place of the compliance demonstrations based on VOC measurements and 
compliance calculations.
    We are proposing that this alternative apply to all coatings 
subject to the Aerospace NESHAP, including specialty coatings, 
topcoats, primers and chemical milling maskants. Due to the existence 
of the Aerospace NESHAP for nearly 20 years and the prevalence of state 
and regional VOC regulations for many types of coatings, coating 
manufacturers have come to recognize the value of providing 
documentation of HAP and VOC content to their customers to facilitate 
compliance demonstrations with state and federal regulations. For all 
coatings subject to the Aerospace NESHAP, the EPA has determined that 
onsite purchase records and the manufacturer's supplied data sheets for 
the coatings will provide sufficient information to establish 
compliance with the content limit standards in the Aerospace NESHAP.
    If a facility elects to comply with the averaging provisions in 40 
CFR 63.743(d), the facility is also required to comply with all related 
averaging provisions in the Aerospace NESHAP for all coatings included 
in averaging (e.g., compliance determination provisions in 40 CFR 
63.749(d) and (h); procedures and methods in 40 CFR 63.750(d), (f), (l) 
and (n); recordkeeping

[[Page 8427]]

provisions in 40 CFR 63.752(c) and (f); and reporting provisions in 
63.753(c) and (e)). Note that, in complying with the current averaging 
provisions, facilities may already use manufacturers' data for coatings 
to determine the organic HAP and VOC weight fraction of coatings to 
perform the calculations in 40 CFR 63.750(d), (f), (l) and (n).

F. What compliance dates are we proposing?

    The EPA is proposing that all of the amendments being proposed in 
this action would be effective on the date 60 days after these proposed 
amendments are final, with one exception. The one exception is that 
existing specialty coating affected sources (i.e., existing on the date 
these changes are final) would have 1 year after the date this rule is 
final to comply with the standards for specialty coatings proposed in 
40 CFR 63.745(c)(5) and (6) (HAP and VOC limits for specified coatings) 
and the provisions in 40 CFR 63.745(f) (coating application equipment) 
and 40 CFR 63.745(g) (control of inorganic HAP emissions). The EPA is 
proposing this compliance schedule so that existing sources would have 
time to develop the recordkeeping and reporting systems needed to 
comply with the requirements for specialty coatings. Facilities may 
also need this time to identify alternative coatings for those that are 
not currently compliant with the HAP or VOC content limits and to take 
any steps needed to upgrade specialty coating operations to comply with 
the application equipment requirements in 40 CFR 63.745(f) and the 
inorganic HAP emissions requirements in 40 CFR 63.745(g).
    The tasks necessary for existing facilities to comply with the 
other proposed amendments require no time or resources. Therefore, EPA 
believes that existing facilities will be able to comply with the other 
proposed amendments, including those related to SSM periods, as soon as 
the final rule is effective, which will be the date 60 days after 
publication of the final rule. Therefore, the EPA is specifically 
soliciting comment and additional data on the burden of complying with 
the other proposed amendments.

V. Summary of Cost, Environmental and Economic Impacts

A. What are the affected sources?

    The EPA estimates, based on the responses to the 2011 ICR, that 
there are 144 major source facilities that are engaged in aerospace 
manufacturing and rework surface coating operations. The EPA estimates 
that 109 facilities likely would be affected by the proposed limits for 
specialty coatings and the requirements to use high-efficiency 
application equipment for specialty coatings, also based on the 
responses to the 2011 ICR.

B. What are the air quality impacts?

    The EPA estimates that annual HAP emissions from specialty coatings 
are about 360 tpy; inorganic HAP emissions are about 5 tpy and the 
remainder are organic HAP. The estimated emission reductions are 58 
tons of HAP, which would be achieved from the proposed regulation of 
specialty coatings. The EPA estimated that these emission reductions 
would result from the proposed requirements to use high-efficiency 
application equipment and also from the application of the HAP content 
limits to specialty coatings.

C. What are the cost impacts?

    The EPA estimates that the annual cost impacts would be about 
$590,000 per year. The cost impacts would be attributed to monitoring 
and recordkeeping costs for complying with the specialty coating HAP 
content limits. The cost per facility was estimated based on the number 
of specialty coatings used at each facility, as reported in the 2011 
ICR. The costs are based on an assumption of 1 hour of technical labor 
for annual recordkeeping and reporting for each specialty coating used 
by a facility, plus additional management and clerical hours 
representing a fraction of the technical labor hours.
    The EPA does not have sufficient data from the 2011 ICR to estimate 
the total cost impacts for specialty coatings having to comply with the 
proposed high-efficiency application equipment requirement. Because 
high-efficiency application equipment generates less coating overspray 
than conventional equipment, the costs of upgrading to new equipment 
can be offset by cost savings from reduced coating consumption and 
reduced spray booth filter maintenance. For these reasons, many 
facilities are likely to have already switched to high-efficiency 
application methods for specialty coating operations, as they are 
already required to for primer and topcoat application operations. For 
example, the average volume of specialty coatings used per facility is 
3,000 gallons per year, based on the 2011 ICR data. The estimated 
purchase cost for a professional quality HVLP spray gun is $700 for the 
gun and hoses. If the average facility had to purchase three new spray 
guns, and the facility was spending an average of $30 per gallon of 
spray applied coating, the facility would need to see a decrease in 
coating consumption of only 70 gallons per year (about a 3-percent 
reduction) to recover the initial cost of those three spray guns in 1 
year.
    The EPA expects some additional potential cost savings from the 
proposal to include an alternative compliance demonstration provision 
in 40 CFR 63.750(c), (e), (k) and (m). However, we do not have 
sufficient data to estimate the cost savings associated with the 
proposed alternative compliance demonstration. However, the estimated 
cost to perform an analysis of VOC content according to EPA Method 24, 
based on published vendor data, is about $575 per sample. Because the 
proposed alternative compliance demonstration would allow facilities to 
use coating manufacturers' documentation of VOC content based on 
coating composition, the cost of these coating analyses using EPA 
Method 24 would be avoided.
    The EPA's cost analyses are documented in the memorandum, 
Methodology for Estimating Control Costs for Specialty Coating 
Operations in the Aerospace Source Category, January 2014, in the 
docket for this rulemaking.
    EPA is specifically soliciting comment and additional data on the 
cost impacts associated with using coatings that are compliant with the 
proposed limits for specialty coatings.

D. What are the economic impacts?

    Economic impact analyses focus on changes in market prices and 
output levels. If changes in market prices and output levels in the 
primary markets are significant enough, impacts on other markets are 
also examined. Both the magnitude of costs needed to comply with the 
rule and the distribution of these costs among affected facilities can 
have a role in determining how the market will change in response to a 
rule.
    This rule applies to the surface coating and related operations at 
facilities that are major sources and are engaged, either in part or in 
whole, in the manufacture or rework of commercial, civil or military 
aerospace vehicles or components. The proposed rule would add 
recordkeeping and reporting provisions for specialty coating 
operations, but would not change the compliance costs for operations 
already being regulated by the existing emission standards. Therefore, 
the annual costs were calculated for only the 109 Aerospace 
Manufacturing and Rework Facilities that reported having specialty 
coating operations.

[[Page 8428]]

    The estimated annual costs for this proposed rule are less than $1 
million in the first year and in succeeding years (less than $850,000 
in the first year and less than $600,000 in succeeding years). These 
costs are estimated for the 109 facilities that, based on information 
reported by facilities, appear to have specialty coating operations. 
Thus, the average cost per facility is less than $10,000 per year. 
These costs are small compared to sales for the companies in aerospace 
manufacturing and reworking. For example, in 2012 the average annual 
value of shipments (a rough estimate of sales) for firms in the 
category of ``other aircraft parts and auxiliary equipment 
manufacturing'' was almost $50 million (Source: U.S. Census Bureau, 
2012 Economic Census for NAICS 336413 for 2012). In this case the cost-
to-sales estimate would be approximately 0.02 percent of sales for each 
firm. Costs this small would not have significant market impacts, 
whether they were absorbed by the firm or passed on as price increases.
    The EPA does not know of any firms that are small entities and 
using specialty coatings that are potentially subject to this proposed 
rule. Because no small firms face control costs, there is no 
significant impact on small entities. Therefore, we do not expect these 
proposed amendments to have a significant impact on a substantial 
number of small entities.

E. What are the benefits?

    We anticipate this rulemaking to reduce organic and inorganic HAP 
emissions by approximately 58 tons each year. These avoided emissions 
will result in improvements in air quality and reduced negative health 
effects associated with exposure to air pollution of these emissions. 
However, we have not quantified or monetized the benefits of reducing 
these emissions for this rulemaking because the estimated costs for 
this action are less than $100 million.

VI. Request for Comments

    We solicit comments on all aspects of this proposed action. In 
addition to general comments on this proposed action, we are also 
interested in additional data that may improve the risk assessments and 
other analyses. We are specifically interested in receiving any 
improvements to the data used in the site-specific emissions profiles 
used for risk modeling. Such data should include supporting 
documentation in sufficient detail to allow characterization of the 
quality and representativeness of the data or information. Section VII 
of this preamble provides more information on submitting data.

VII. Submitting Data Corrections

    The site-specific emissions profiles used in the source category 
risk and demographic analyses and instructions are available for 
download on the RTR Web site at: https://www.epa.gov/ttn/atw/rrisk/rtrpg.html. The data files include detailed information for each HAP 
emissions release point for the facilities in the source category.
    If you believe that the data are not representative or are 
inaccurate, please identify the data in question, provide your reason 
for concern and provide any ``improved'' data that you have, if 
available. When you submit data, we request that you provide 
documentation of the basis for the revised values to support your 
suggested changes. To submit comments on the data downloaded from the 
RTR page, complete the following steps:
    1. Within this downloaded file, enter suggested revisions to the 
data fields appropriate for that information.
    2. Fill in the commenter information fields for each suggested 
revision (i.e., commenter name, commenter organization, commenter email 
address, commenter phone number and revision comments).
    3. Gather documentation for any suggested emissions revisions 
(e.g., performance test reports, material balance calculations, etc.).
    4. Send the entire downloaded file with suggested revisions in 
Microsoft[supreg] Access format and all accompanying documentation to 
Docket ID No. EPA-HQ-OAR-2014-0830 (through one of the methods 
described in the ADDRESSES section of this preamble).
    5. If you are providing comments on a single facility or multiple 
facilities, you need only submit one file for all facilities. The file 
should contain all suggested changes for all sources at that facility. 
We request that all data revision comments be submitted in the form of 
updated Microsoft[supreg] Excel files that are generated by the 
Microsoft[supreg] Access file. These files are provided on the RTR Web 
site at: https://www.epa.gov/ttn/atw/rrisk/rtrpg.html.

VIII. Statutory and Executive Order Reviews

    Additional information about these statutes and Executive Orders 
can be found at https://www2.epa.gov/laws-regulations/laws-and-executive-orders.

A. Executive Order 12866: Regulatory Planning and Review and Executive 
Order 13563: Improving Regulation and Regulatory Review

    This action is not a significant regulatory action and was 
therefore not submitted to the OMB for review.

B. Paperwork Reduction Act (PRA)

    The information collection activities in this proposed rule have 
been submitted for approval to the OMB under the PRA. The ICR document 
that the EPA prepared has been assigned EPA ICR number 1687.10. You can 
find a copy of the ICR in the docket for this rule, and it is briefly 
summarized here.
    Respondents are owners or operators of aerospace manufacturing and 
rework operations. The proposed rule would add recordkeeping and 
reporting provisions for specialty coating operations, but would not 
change the recordkeeping and reporting provisions for any other types 
of operations. Therefore, of the 144 Aerospace Manufacturing and Rework 
Facilities subject to the Aerospace NESHAP, the annual costs for 
increased recordkeeping and reporting would apply to only the 109 
Aerospace Manufacturing and Rework Facilities that reported having 
specialty coating operations. Respondents must keep records of the 
specialty coatings used at the facility, including the name and VOC 
content of the coating, the HAP and VOC emitted per gallon of coating 
and the monthly volume of each coating used. Respondents must also 
submit semiannual reports of noncompliance. Recordkeeping and reporting 
of monitored parameters related to air pollution control technologies 
is required if controls are used to demonstrate compliance with the 
standards. The reports and records will be used to determine compliance 
with the standards.
    Respondents/affected entities: Aerospace manufacturing and rework 
facilities using specialty coatings.
    Respondent's obligation to respond: Mandatory (40 CFR part 63, 
subpart GG).
    Estimated number of respondents: 109 facilities using specialty 
coatings.
    Frequency of response: Initially, occasionally and semiannually.
    Total estimated burden: 6,914 hours (per year) for the responding 
facilities and 148 hours (per year) for the agency. These are estimates 
for the average annual burden for the first 3 years after the rule is 
final. Burden is defined at 5 CFR 1320.3(b).
    Total estimated cost: $695,570 (per year), which includes no 
annualized

[[Page 8429]]

capital or operation and maintenance costs, for the responding 
facilities and $8,740 (per year) for the agency. These are estimates 
for the average annual cost for the first 3 years after the rule is 
final.
    An agency may not conduct or sponsor, and a person is not required 
to respond to, a collection of information unless it displays a 
currently valid OMB control number. The OMB control numbers for the 
EPA's regulations in 40 CFR are listed in 40 CFR part 9. To comment on 
the agency's need for this information, the accuracy of the provided 
burden estimates and any suggested methods for minimizing respondent 
burden, the EPA has established a public docket for this rule, which 
includes this ICR, under Docket ID No. EPA-HQ-OAR-2014-0830.
    Submit your comments on the Agency's need for this information, the 
accuracy of the provided burden estimates and any suggested methods for 
minimizing respondent burden to the EPA using the docket identified at 
the beginning of this rule. You may also send your ICR-related comments 
to OMB's Office of Information and Regulatory Affairs via email to 
oria_submissions@omb.eop.gov, Attention: Desk Officer for the EPA. 
Since OMB is required to make a decision concerning the ICR between 30 
and 60 days after receipt, OMB must receive comments no later than 
March 19, 2015. The EPA will respond to any ICR-related comments in the 
final rule.

C. Regulatory Flexibility Act (RFA)

    I certify that this action will not have a significant economic 
impact on a substantial number of small entities under the RFA. This 
action will not impose any requirements on small entities. No 
facilities meeting the Small Business Administration's definition of a 
small business would face significant control costs, based on the 
economic impact analysis completed for this action. The results of this 
analysis are summarized in section V.D of this preamble and can be 
found in the memorandum, Economic Impact Analysis for Proposed National 
Emission Standards for Aerospace Manufacturing and Rework Facilities, 
December 3, 2014. A copy of this memorandum is in the docket for this 
rulemaking.

D. Unfunded Mandates Reform Act (UMRA)

    This action does not contain an unfunded mandate of $100 million or 
more as described in the UMRA, 2 U.S.C. 1531-1538, and does not 
significantly or uniquely affect small governments. The action imposes 
no enforceable duty on any state, local or tribal governments or the 
private sector.

E. Executive Order 13132: Federalism

    This action does not have federalism implications. It will not have 
substantial direct effects on the states, on the relationship between 
the national government and the states or on the distribution of power 
and responsibilities among the various levels of government.

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

    This action does not have tribal implications as specified in 
Executive Order 13175. No tribal facilities are known to be engaged in 
the aerospace manufacturing or rework surface coating operations that 
would be affected by this action. Thus, Executive Order 13175 does not 
apply to this action.

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

    This action is not subject to Executive Order 13045 because it is 
not economically significant as defined in Executive Order 12866, and 
because the EPA does not believe the environmental health or safety 
risks addressed by this action present a disproportionate risk to 
children. This action's health and risk assessments are contained in 
sections III.A and B and sections IV.B and C of this preamble.

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

    This action is not subject to Executive Order 13211 because it is 
not a significant regulatory action under Executive Order 12866.

I. National Technology Transfer and Advancement Act (NTTAA)

    This rulemaking does not involve technical standards.

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

    The EPA believes the human health or environmental risk addressed 
by this action will not have potential disproportionately high and 
adverse human health or environmental effects on minority, low-income 
or indigenous populations.
    These proposed standards will improve public health and welfare, 
now and in the future, by reducing HAP emissions contributing to 
environmental and human health impacts. These reductions in HAP 
associated with the rule are expected to benefit all populations.
    To examine the potential for any environmental justice issues that 
might be associated with the Aerospace Manufacturing and Rework source 
category, we evaluated the distributions of HAP related cancer and non-
cancer risks across different social, demographic and economic groups 
within the populations living near the facilities where this source 
category is located. The methods used to conduct demographic analyses 
for this proposed rule are described in the document, Risk and 
Technology Review--Analysis of Socio-Economic Factors for Populations 
Living Near Aerospace Facilities, which may be found in the docket for 
this rulemaking (Docket ID No. EPA-HQ-OAR-2014-0830).
    In the demographics analysis, we focused on populations within 50 
km of the facilities in this source category with emissions sources 
subject to the MACT standard. More specifically, for these populations, 
we evaluated exposures to HAP that could result in cancer risks of 1-
in-1 million or greater. We compared the percentages of particular 
demographic groups within the focused populations to the total 
percentages of those demographic groups nationwide. The results of this 
analysis are documented in the document, Risk and Technology Review--
Analysis of Socio-Economic Factors for Populations Living Near 
Aerospace Facilities.

List of Subjects in 40 CFR Part 63

    Environmental protection, Air pollution control, Hazardous 
substances, Reporting and recordkeeping requirements.

    Dated: January 22, 2015.
Gina McCarthy,
Administrator.
    For the reasons stated in the preamble, part 63 of title 40, 
chapter I, of the Code of Federal Regulations is proposed to be amended 
as follows:

PART 63--NATIONAL EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS 
FOR SOURCE CATEGORIES

0
1. The authority citation for part 63 continues to read as follows:

    Authority: 42 U.S.C. 7401, et seq.

Subpart GG--National Emission Standards for Aerospace Manufacturing 
and Rework Facilities

0
2. Section 63.741 is amended by:

[[Page 8430]]

0
a. Revising paragraph (c) introductory text;
0
b. Redesignating paragraphs (c)(4) through (c)(7) as paragraphs (c)(5) 
through (c)(8);
0
c. Adding new paragraph (c)(4);
0
d. Revising newly redesignated paragraph (c)(8); and
0
e. Revising paragraphs (f) and (g).
    The revisions and addition read as follows:


Sec.  63.741  Applicability and designation of affected sources.

* * * * *
    (c) Affected sources. The affected sources to which the provisions 
of this subpart apply are specified in paragraphs (c)(1) through (8) of 
this section. The activities subject to this subpart are limited to the 
manufacture or rework of aerospace vehicles or components as defined in 
this subpart. Where a dispute arises relating to the applicability of 
this subpart to a specific activity, the owner or operator shall 
demonstrate whether or not the activity is regulated under this 
subpart.
* * * * *
    (4) For organic HAP or VOC emissions, each specialty coating 
application operation, which is the total of all specialty coating 
applications at the facility.
* * * * *
    (8) For inorganic HAP emissions, each spray booth or hangar that 
contains a primer, topcoat or specialty coating application operation 
subject to Sec.  63.745(g), or a depainting operation subject to Sec.  
63.746(b)(4).
* * * * *
    (f) This subpart does not regulate research and development, 
quality control and laboratory testing activities, chemical milling, 
metal finishing, electrodeposition (except for electrodeposition of 
paints), composites processing (except for cleaning and coating of 
composite parts or components that become part of an aerospace vehicle 
or component as well as composite tooling that comes in contact with 
such composite parts or components prior to cure), electronic parts and 
assemblies (except for cleaning and topcoating of completed 
assemblies), manufacture of aircraft transparencies and wastewater 
operations at aerospace facilities. These requirements do not apply to 
the rework of aircraft or aircraft components if the holder of the 
Federal Aviation Administration (FAA) design approval, or the holder's 
licensee, is not actively manufacturing the aircraft or aircraft 
components. These requirements also do not apply to parts and 
assemblies not critical to the vehicle's structural integrity or flight 
performance. The requirements of this subpart also do not apply to 
primers, topcoats, specialty coatings, chemical milling maskants, 
strippers and cleaning solvents containing HAP and VOC at 
concentrations less than 0.1 percent by mass for carcinogens or 1.0 
percent by mass for noncarcinogens, as determined from manufacturer's 
representations, such as in a material safety data sheet or product 
data sheet or testing. Additional specific exemptions from regulatory 
coverage are set forth in paragraphs (e), (g), (h), (i) and (j) of this 
section and Sec. Sec.  63.742, 63.744(a)(1), (b), (e), 63.745(a), 
(f)(3), (g)(4), 63.746(a), (b)(5), 63.747(c)(3) and 63.749(d).
    (g) The requirements for primers, topcoats, specialty coatings and 
chemical milling maskants in Sec. Sec.  63.745 and 63.747 do not apply 
to the use of low-volume coatings in these categories for which the 
annual total of each separate formulation used at a facility does not 
exceed 189 liters (50 gal), and the combined annual total of all such 
primers, topcoats, specialty coatings and chemical milling maskants 
used at a facility does not exceed 757 liters (200 gal). Primers, 
topcoats and specialty coatings exempted under paragraph (f) of this 
section and under Sec.  63.745(f)(3) and (g)(4) are not included in the 
50 and 200 gal limits. Chemical milling maskants exempted under Sec.  
63.747(c)(3) are also not included in these limits.
* * * * *
0
3. Section 63.742 is amended by revising the definitions for ``Chemical 
milling maskant''; ``Softener''; and ``Stripper'' to read as follows:


Sec.  63.742  Definitions.

* * * * *
    Chemical milling maskant means a coating that is applied directly 
to aluminum components to protect surface areas when chemical milling 
the component with a Type I or Type II etchant. Type I chemical milling 
maskants are used with a Type I etchant and Type II chemical milling 
maskants are used with a Type II etchant. This definition does not 
include bonding maskants, critical use and line sealer maskants and 
seal coat maskants. Additionally, maskants that must be used with a 
combination of Type I or II etchants and any of the above types of 
maskants (i.e., bonding, critical use and line sealer and seal coat) 
are also not included in this definition. (See also Type I and Type II 
etchant definitions.)
* * * * *
    Softener means a liquid that is applied to an aerospace vehicle or 
component to degrade coatings such as primers, topcoats and specialty 
coatings specifically as a preparatory step to subsequent depainting by 
non-chemical based depainting equipment. Softeners may contain VOC, but 
shall not contain any HAP as determined from MSDS's or manufacturer 
supplied information.
* * * * *
    Stripper means a liquid that is applied to an aerospace vehicle or 
component to remove permanent coatings such as primers, topcoats and 
specialty coatings.
* * * * *
0
4. Section 63.743 is amended by:
0
a. Revising paragraphs (a)(2), (8), and (10);
0
b. Removing and reserving paragraph (b);
0
c. Revising paragraphs (d)(1), (2), and (3);
0
d. Removing and reserving paragraphs (d)(4) and (5);
0
e. Adding paragraph (e).
    The revisions and addition read as follows:


Sec.  63.743  Standards: General.

    (a) * * *
    (2) Sec.  63.5, Preconstruction review and notification 
requirements; and
* * * * *
    (8) For the purposes of this subpart, each owner or operator is to 
be provided 30 calendar days to present additional information to the 
Administrator after he/she is notified of the intended denial of a 
compliance extension request submitted under either Sec.  63.6(i)(4) or 
(5), rather than 15 calendar days as provided for in Sec.  
63.6(i)(12)(iii)(B) and Sec.  63.6(i)(13)(iii)(B).
* * * * *
    (10) For the purposes of compliance with the requirements of Sec.  
63.5(b)(4) of the General Provisions and this subpart, owners or 
operators of existing primer, topcoat or specialty coating application 
operations and depainting operations who construct or reconstruct a 
spray booth or hangar that does not have the potential to emit 10 tons/
yr or more of an individual inorganic HAP or 25 tons/yr or more of all 
inorganic HAP combined shall only be required to notify the 
Administrator of such construction or reconstruction on an annual 
basis. Notification shall be submitted on or before March 1 of each 
year and shall include the information required in Sec.  63.5(b)(4) for 
each such spray booth or hangar constructed or reconstructed during the 
prior calendar year, except that such information shall be limited to 
inorganic HAP's. No advance notification or written approval from the 
Administrator pursuant to Sec.  63.5(b)(3) shall be required for the

[[Page 8431]]

construction or reconstruction of such a spray booth or hangar unless 
the booth or hangar has the potential to emit 10 tons/yr or more of an 
individual inorganic HAP or 25 tons/yr or more of all inorganic HAP 
combined.
* * * * *
    (d) * * *
    (1) Each owner or operator of a new or existing source shall use 
any combination of primers, topcoats (including self-priming topcoats), 
specialty coatings, Type I chemical milling maskants or Type II 
chemical milling maskants such that the monthly volume-weighted average 
organic HAP and VOC contents of the combination of primers, topcoats, 
specialty coatings, Type I chemical milling maskants or Type II 
chemical milling maskants, as determined in accordance with the 
applicable procedures set forth in Sec.  63.750, complies with the 
specified content limits in Sec. Sec.  63.745(c) and 63.747(c), unless 
the permitting agency specifies a shorter averaging period as part of 
an ambient ozone control program.
    (2) Averaging is allowed only for uncontrolled primers, topcoats 
(including self-priming topcoats), specialty coatings, Type I chemical 
milling maskants or Type II chemical milling maskants.
    (3) Averaging is not allowed between specialty coating types 
defined in Appendix A to this subpart, or between the different types 
of coatings specified in paragraphs (d)(3)(i) through (vii) of this 
section.
    (i) Primers and topcoats (including self-priming topcoats).
    (ii) Type I and Type II chemical milling maskants.
    (iii) Primers and chemical milling maskants.
    (iv) Topcoats and chemical milling maskants.
    (v) Primers and specialty coatings.
    (vi) Topcoats and specialty coatings.
    (vii) Chemical milling maskants and specialty coatings.
* * * * *
    (e) At all times, the owner or operator must operate and maintain 
any affected source, including associated air pollution control 
equipment and monitoring equipment, in a manner consistent with safety 
and good air pollution control practices for minimizing emissions. The 
general duty to minimize emissions does not require the owner or 
operator to make any further efforts to reduce emissions if levels 
required by the applicable standard have been achieved. Determination 
of whether a source is operating in compliance with operation and 
maintenance requirements will be based on information available to the 
Administrator which may include, but is not limited to, monitoring 
results, review of operation and maintenance procedures, review of 
operation and maintenance records and inspection of the source.
0
5. Section 63.744 is amended by:
0
a. Revising paragraph (a) introductory text; and
0
b. Correcting the numerical order of paragraphs (a)(3) and (4).
    The revision reads as follows:


Sec.  63.744  Standards: Cleaning operations.

    (a) Housekeeping measures. Each owner or operator of a new or 
existing cleaning operation subject to this subpart shall comply with 
the requirements in paragraphs (a)(1) through (4) of this section 
unless the cleaning solvent used is identified in Table 1 of this 
section or contains HAP and VOC below the de minimis levels specified 
in Sec.  63.741(f).
* * * * *
0
6. Section 63.745 is amended by:
0
a. Revising the section heading;
0
b. Revising paragraphs (a), (b), and (c) introductory text;
0
c. Adding paragraphs (c)(5), (c)(6) and Table 1;
0
d. Revising paragraphs (e) introductory text and (e)(1);
0
e. Revising paragraphs (f) introductory text, (f)(1) introductory text 
and (f)(2);
0
f. Revising paragraphs (g) introductory text, (g)(2)(i), (g)(2)(ii), 
and (g)(2)(iii)(B).
    The revisions and additions read as follows:


Sec.  63.745  Standards: Primer, topcoat and specialty coating 
application operations.

    (a) Each owner or operator of a new or existing primer, topcoat or 
specialty coating application operation subject to this subpart shall 
comply with the requirements specified in paragraph (c) of this section 
for those coatings that are uncontrolled (no control device is used to 
reduce organic HAP emissions from the operation), and in paragraph (d) 
of this section for those coatings that are controlled (organic HAP 
emissions from the operation are reduced by the use of a control 
device). Aerospace equipment that is no longer operational, intended 
for public display and not easily capable of being moved is exempt from 
the requirements of this section.
    (b) Each owner or operator shall conduct the handling and transfer 
of primers, topcoats and specialty coatings to or from containers, 
tanks, vats, vessels and piping systems in such a manner that minimizes 
spills.
    (c) Uncontrolled coatings--organic HAP and VOC content levels. Each 
owner or operator shall comply with the organic HAP and VOC content 
limits specified in paragraphs (c)(1) through (6) of this section for 
those coatings that are uncontrolled.
* * * * *
    (5) Organic HAP emissions from specialty coatings shall be limited 
to an organic HAP content level of no more than the HAP content limit 
specified in Table 1 of this section for each applicable specialty 
coating type.
    (6) VOC emissions from specialty coatings shall be limited to a VOC 
content level of no more than the VOC content limit specified in Table 
1 of this section for each applicable specialty coating type.

         Table 1--Specialty Coatings--HAP and VOC Content Limits
------------------------------------------------------------------------
                                           HAP limit g/L   VOC Limit g/L
              Coating type                  (lb/gallon)     (lb/gallon)
                                                \1\             \1\
------------------------------------------------------------------------
Ablative Coating........................       600 (5.0)       600 (5.0)
Adhesion Promoter.......................       890 (7.4)       890 (7.4)
Adhesive Bonding Primers: Cured at 250         850 (7.1)       850 (7.1)
 [deg]F or below........................
Adhesive Bonding Primers: Cured above        1,030 (8.6)     1,030 (8.6)
 250 [deg]F.............................
Commercial Interior Adhesive............       760 (6.3)       760 (6.3)
Cyanoacrylate Adhesive..................     1,020 (8.5)     1,020 (8.5)
Fuel Tank Adhesive......................       620 (5.2)       620 (5.2)
Nonstructural Adhesive..................       360 (3.0)       360 (3.0)
Rocket Motor Bonding Adhesive...........       890 (7.4)       890 (7.4)
Rubber-based Adhesive...................       850 (7.1)       850 (7.1)
Structural Autoclavable Adhesive........        60 (0.5)        60 (0.5)
Structural Nonautoclavable Adhesive.....       850 (7.1)       850 (7.1)

[[Page 8432]]

 
Antichafe Coating.......................       660 (5.5)       660 (5.5)
Bearing Coating.........................       620 (5.2)       620 (5.2)
Caulking and Smoothing Compounds........       850 (7.1)       850 (7.1)
Chemical Agent-Resistant Coating........       550 (4.6)       550 (4.6)
Clear Coating...........................       720 (6.0)       720 (6.0)
Commercial Exterior Aerodynamic                650 (5.4)       650 (5.4)
 Structure Primer.......................
Compatible Substrate Primer.............       780 (6.5)       780 (6.5)
Corrosion Prevention Compound...........       710 (5.9)       710 (5.9)
Cryogenic Flexible Primer...............       645 (5.4)       645 (5.4)
Cryoprotective Coating..................       600 (5.0)       600 (5.0)
Dry Lubricative Material................       880 (7.3)       880 (7.3)
Electric or Radiation-Effect Coating....       800 (6.7)       800 (6.7)
Electrostatic Discharge and                    800 (6.7)       800 (6.7)
 Electromagnetic Interference (EMI)
 Coating................................
Elevated-Temperature Skydrol-Resistant         740 (6.2)       740 (6.2)
 Commercial Primer......................
Epoxy Polyamide Topcoat.................       660 (5.5)       660 (5.5)
Fire-Resistant (interior) Coating.......       800 (6.7)       800 (6.7)
Flexible Primer.........................       640 (5.3)       640 (5.3)
Flight-Test Coatings: Missile or Single        420 (3.5)       420 (3.5)
 Use Aircraft...........................
Flight-Test Coatings: All Other.........       840 (7.0)       840 (7.0)
Fuel-Tank Coating.......................       720 (6.0)       720 (6.0)
High-Temperature Coating................       850 (7.1)       850 (7.1)
Insulation Covering.....................       740 (6.2)       740 (6.2)
Intermediate Release Coating............       750 (6.3)       750 (6.3)
Lacquer.................................       830 (6.9)       830 (6.9)
Bonding Maskant.........................    1,230 (10.3)    1,230 (10.3)
Critical Use and Line Sealer Maskant....     1,020 (8.5)     1,020 (8.5)
Seal Coat Maskant.......................    1,230 (10.3)    1,230 (10.3)
Metalized Epoxy Coating.................       740 (6.2)       740 (6.2)
Mold Release............................       780 (6.5)       780 (6.5)
Optical Anti-Reflective Coating.........       750 (6.3)       750 (6.3)
Part Marking Coating....................       850 (7.1)       850 (7.1)
Pretreatment Coating....................       780 (6.5)       780 (6.5)
Rain Erosion-Resistant Coating..........       850 (7.1)       850 (7.1)
Rocket Motor Nozzle Coating.............       660 (5.5)       660 (5.5)
Scale Inhibitor.........................       880 (7.3)       880 (7.3)
Screen Print Ink........................       840 (7.0)       840 (7.0)
Extrudable/Rollable/Brushable Sealant...       280 (2.3)       280 (2.3)
Sprayable Sealant.......................       600 (5.0)       600 (5.0)
Silicone Insulation Material............       850 (7.1)       850 (7.1)
Solid Film Lubricant....................       880 (7.3)       880 (7.3)
Specialized Function Coating............       890 (7.4)       890 (7.4)
Temporary Protective Coating............       320 (2.7)       320 (2.7)
Thermal Control Coating.................       800 (6.7)       800 (6.7)
Wet Fastener Installation Coating.......       675 (5.6)       675 (5.6)
Wing Coating............................       850 (7.1)       850 (7.1)
------------------------------------------------------------------------
\1\ Coating limits for HAP are expressed in terms of mass (grams or
  pounds) of HAP per volume (liters or gallons) of coating less water.
  Coating limits for VOC are expressed in terms of mass (grams or
  pounds) of VOC per volume (liters or gallons) of coating less water
  and less exempt solvent.

* * * * *
    (e) Compliance methods. Compliance with the organic HAP and VOC 
content limits specified in paragraphs (c)(1) through (6) of this 
section shall be accomplished by using the methods specified in 
paragraphs (e)(1) and (2) of this section either by themselves or in 
conjunction with one another.
    (1) Use primers, topcoats (including self-priming topcoats) and 
specialty coatings with HAP and VOC content levels equal to or less 
than the limits specified in paragraphs (c)(1) through (6) of this 
section; or
* * * * *
    (f) Application equipment. Except as provided in paragraph (f)(3) 
of this section, each owner or operator of a new or existing primer, 
topcoat (including self-priming topcoat) or specialty coating 
application operation subject to this subpart in which any of the 
coatings contain organic HAP or VOC shall comply with the requirements 
specified in paragraphs (f)(1) and (2) of this section.
    (1) All primers, topcoats (including self-priming topcoats) and 
specialty coatings shall be applied using one or more of the 
application techniques specified in paragraphs (f)(1)(i) through (ix) 
of this section.
* * * * *
    (2) All application devices used to apply primers, topcoats 
(including self-priming topcoats) or specialty coatings shall be 
operated according to company procedures, local specified operating 
procedures and/or the manufacturer's specifications, whichever is most 
stringent, at all times. Equipment modified by the facility shall 
maintain a transfer efficiency equivalent to HVLP and electrostatic 
spray application techniques.
* * * * *
    (g) Inorganic HAP emissions. Except as provided in paragraph (g)(4) 
of this section, each owner or operator of a new or existing primer, 
topcoat or specialty coating application operation subject to this 
subpart in which any of the coatings that are spray applied contain

[[Page 8433]]

inorganic HAP, shall comply with the applicable requirements in 
paragraphs (g)(1) through (3) of this section.
* * * * *
    (2) * * *
    (i) For existing sources, the owner or operator must choose one of 
the following:
    (A) Before exhausting it to the atmosphere, pass the air stream 
through a dry particulate filter system certified using the methods 
described in Sec.  63.750(o) to meet or exceed the efficiency data 
points in Tables 2 and 3 of this section; or
    (C) Before exhausting it to the atmosphere, pass the air stream 
through an air pollution control system that meets or exceeds the 
efficiency data points in Tables 2 and 3 of this section and is 
approved by the permitting authority.

Table 2--Two-Stage Arrestor; Liquid Phase Challenge for Existing Sources
------------------------------------------------------------------------
                                                            Aerodynamic
          Filtration efficiency  requirement, %            particle size
                                                           range, [mu]m
------------------------------------------------------------------------
>90.....................................................            >5.7
>50.....................................................            >4.1
>10.....................................................            >2.2
------------------------------------------------------------------------


 Table 3--Two-Stage Arrestor; Solid Phase Challenge for Existing Sources
------------------------------------------------------------------------
                                                            Aerodynamic
          Filtration efficiency  requirement, %            particle size
                                                           range, [mu]m
------------------------------------------------------------------------
>90.....................................................            >8.1
>50.....................................................            >5.0
>10.....................................................            >2.6
------------------------------------------------------------------------

    (ii) For new sources, either:
    (A) Before exhausting it to the atmosphere, pass the air stream 
through a dry particulate filter system certified using the methods 
described in Sec.  63.750(o) to meet or exceed the efficiency data 
points in Tables 4 and 5 of this section; or (B) Before exhausting it 
to the atmosphere, pass the air stream through an air pollution control 
system that meets or exceeds the efficiency data points in Tables 4 and 
5 of this section and is approved by the permitting authority.

  Table 4--Three-Stage Arrestor; Liquid Phase Challenge for New Sources
------------------------------------------------------------------------
                                                            Aerodynamic
          Filtration efficiency  requirement, %            particle size
                                                           range, [mu]m
------------------------------------------------------------------------
>95.....................................................           >2.0
>80.....................................................           >1.0
>65.....................................................           >0.42
------------------------------------------------------------------------


  Table 5--Three-Stage Arrestor; Solid Phase Challenge for New Sources
------------------------------------------------------------------------
                                                            Aerodynamic
          Filtration efficiency  requirement, %            particle size
                                                           range, [mu]m
------------------------------------------------------------------------
>95.....................................................           >2.5
>85.....................................................           >1.1
>75.....................................................           >0.70
------------------------------------------------------------------------

    (iii) * * *
    (B) If the primer, topcoat or specialty coating contains chromium 
or cadmium, control shall consist of a HEPA filter system, three-stage 
filter system or other control system equivalent to the three stage 
filter system as approved by the permitting agency.
* * * * *
0
7. Section 63.746 is amended by revising (b)(4)(ii)(A) and (B) to read 
as follows:


Sec.  63.746  Standards: Depainting operations.

* * * * *
    (b) * * *
    (4) * * *
    (ii)(A) For existing sources, pass any air stream removed from the 
enclosed area or closed-cycle depainting system through a dry 
particulate filter system, certified using the method described in 
Sec.  63.750(o) to meet or exceed the efficiency data points in Tables 
2 and 3 of Sec.  63.745, through a baghouse or through a waterwash 
system before exhausting it to the atmosphere.
    (B) For new sources, pass any air stream removed from the enclosed 
area or closed-cycle depainting system through a dry particulate filter 
system certified using the method described in Sec.  63.750(o) to meet 
or exceed the efficiency data points in Tables 4 and 5 of Sec.  63.745 
or through a baghouse before exhausting it to the atmosphere.
* * * * *
0
8. Section 63.749 is amended by:
0
a. Revising paragraphs (a)(1) and (2);
0
b. Adding paragraph (a)(3);
0
c. Revising paragraph (b);
0
d. Revising the heading of paragraph (d), paragraph (d)(4) introductory 
text and paragraph (d)(4)(i);
0
e. Revising paragraph (e) introductory text;
0
f. Adding paragraph (j).
    The revisions and additions read as follows:


Sec.  63.749  Compliance dates and determinations.

    (a) * * * (1) Each owner or operator of an existing affected source 
subject to this subpart shall comply with the requirements of this 
subpart by September 1, 1998, except as specified in paragraphs (a)(2) 
and (3) of this section. Owners or operators of new affected sources 
subject to this subpart shall comply on the effective date or upon 
startup, whichever is later. In addition, each owner or operator shall 
comply with the compliance dates specified in Sec.  63.6(b) and (c) as 
indicated in Table 1 to subpart GG of part 63.
    (2) Owners or operators of existing primer, topcoat or specialty 
coating application operations and depainting operations who construct 
or reconstruct a spray booth or hangar must comply with the new source 
requirements for inorganic HAP specified in Sec. Sec.  63.745(g)(2)(ii) 
and 63.746(b)(4) for that new spray booth or hangar upon startup. Such 
sources must still comply with all other existing source requirements 
by September 1, 1998.
    (3) Each owner or operator of a specialty coating application 
operation that begins construction or reconstruction after [date of 
publication of final rule in the Federal Register] shall be in 
compliance with the requirements of this subpart on [date of 
publication of final rule in the Federal Register] or upon startup, 
whichever is later. Each owner or operator of a specialty coating 
application operation that is existing on [date of publication of final 
rule in the Federal Register] shall be in compliance with the 
requirements of this subpart on or before [date 1 year after date of 
publication of final rule in the Federal Register].
    (b) General. Each facility subject to this subpart shall be 
considered in noncompliance if the owner or operator fails to use a 
control device other than one specified in this subpart that has not 
been approved by the Administrator, as required by Sec.  63.743(c).
* * * * *
    (d) Organic HAP and VOC content levels--primer, topcoat and 
specialty coating application operations --
* * * * *
    (4) The topcoat or specialty coating application operation is 
considered in compliance when the conditions

[[Page 8434]]

specified in paragraphs (d)(4)(i) through (iv) of this section, as 
applicable, and in paragraph (e) of this section are met. Failure to 
meet any of the conditions identified in these paragraphs shall 
constitute noncompliance.
    (i) The topcoat application operation is considered in compliance 
when the conditions specified in paragraphs (d)(4)(i)(A) are met. The 
specialty coating application operation is considered in compliance 
when the conditions specified in paragraphs (d)(4)(i)(B) are met.
    (A) For all uncontrolled topcoats, all values of Hi and 
Ha (as determined using the procedures specified in Sec.  
63.750(c) and (d)) are less than or equal to 420 grams organic HAP per 
liter (3.5 lb/gal) of topcoat (less water) as applied, and all values 
of Gi and Ga (as determined using the procedures 
specified in Sec.  63.750(e) and (f)) are less than or equal to 420 
grams organic VOC per liter (3.5 lb/gal) of topcoat (less water and 
exempt solvents) as applied.
    (B) For all uncontrolled specialty coatings, all values of 
Hi and Ha (as determined using the procedures 
specified in Sec.  63.750(c) and (d)) are less than or equal to the HAP 
content limits specified in Table 1 to Sec.  63.745 for the applicable 
specialty coating types (less water) as applied, and all values of 
Gi and Ga (as determined using the procedures 
specified in Sec.  63.750(e) and (f)) are less than or equal to the VOC 
content limits specified in Table 1 to Sec.  63.745 for the applicable 
specialty coating types (less water and exempt solvents) as applied.
* * * * *
    (e) Inorganic HAP emissions--primer, topcoat and specialty coating 
application operations. For each primer, topcoat or specialty coating 
application operation that emits inorganic HAP, the operation is in 
compliance when:
* * * * *
    (j) Performance tests shall be conducted under such conditions as 
the Administrator specifies to the owner or operator based on 
representative performance of the affected source for the period being 
tested. Representative conditions exclude periods of startup and 
shutdown unless specified by the Administrator or an applicable 
subpart. The owner or operator may not conduct performance tests during 
periods of malfunction. The owner or operator must record the process 
information that is necessary to document operating conditions during 
the test and include in such record an explanation to support that such 
conditions represent normal operation. Upon request, the owner or 
operator shall make available to the Administrator such records as may 
be necessary to determine the conditions of performance tests.
0
9. Section 63.750 is amended by:
0
a. Revising paragraphs (c) introductory text, (d) introductory text and 
(e) introductory text;
0
b. Revising paragraphs (f) introductory text and (f)(1)(iii);
0
c. Revising paragraph (h)(3)(i)(1); and
0
d. Revising paragraphs (k) introductory text, (m) introductory text and 
(o).
    The revisions are as follows:


Sec.  63.750  Test methods and procedures.

* * * * *
    (c) Organic HAP content level determination--compliant primers, 
topcoats and specialty coatings. For those uncontrolled primers, 
topcoats and specialty coatings complying with the primer, topcoat or 
specialty coating organic HAP content limits specified in Sec.  
63.745(c) without being averaged, the procedures in paragraphs (c)(1) 
through (3) of this section shall be used to determine the mass of 
organic HAP emitted per volume of coating (less water) as applied. As 
an alternative to the procedures in paragraphs (c)(1) through (3) of 
this section, an owner or operator may use the coating manufacturer's 
supplied data to demonstrate that organic HAP emitted per volume of 
coating (less water), as applied, is less than or equal to the 
applicable organic HAP limit specified in Sec.  63.745(c).
* * * * *
    (d) Organic HAP content level determination--averaged primers, 
topcoats and specialty coatings. For those uncontrolled primers, 
topcoats and specialty coatings that are averaged together in order to 
comply with the primer, topcoat and specialty coating organic HAP 
content limits specified in Sec.  63.745(c), the following procedure 
shall be used to determine the monthly volume-weighted average mass of 
organic HAP emitted per volume of coating (less water) as applied, 
unless the permitting agency specifies a shorter averaging period as 
part of an ambient ozone control program.
* * * * *
    (e) VOC content level determination--compliant primers, topcoats 
and specialty coatings. For those uncontrolled primers, topcoats and 
specialty coatings complying with the primer, topcoat and specialty 
coating VOC content levels specified in Sec.  63.745(c) without being 
averaged, the procedures in paragraphs (e)(1) through (3) of this 
section shall be used to determine the mass of VOC emitted per volume 
of coating (less water and exempt solvents) as applied. As an 
alternative to the procedures in paragraphs (e)(1) through (3) of this 
section, an owner or operator may use coating manufacturer's supplied 
data to demonstrate that VOC emitted per volume of coating (less water 
and exempt solvents), as applied, is less than or equal to the 
applicable VOC limit specified in Sec.  63.745(c).
* * * * *
    (f) VOC content level determination--averaged primers, topcoats and 
specialty coatings. For those uncontrolled primers, topcoats and 
specialty coatings that are averaged within their respective coating 
category in order to comply with the primer, topcoat and specialty 
coating VOC content limits specified in Sec.  63.745 (c)(2), (4), and 
(6), the following procedure shall be used to determine the monthly 
volume-weighted average mass of VOC emitted per volume of coating (less 
water and exempt solvents) as applied, unless the permitting agency 
specifies a shorter averaging period as part of an ambient ozone 
control program.
    (1) * * *
    (iii) Determine the VOC content of each primer, topcoat and 
specialty coating formulation (less water and exempt solvents) as 
applied using EPA Method 24 or from manufacturer's data.
* * * * *
    (h) * * *
    (3) * * *
    (i)(1) Alternative application method--primers, topcoats and 
specialty coatings. Each owner or operator seeking to use an 
alternative application method (as allowed in Sec.  63.745(f)(1)(ix)) 
in complying with the standards for primers, topcoats and specialty 
coatings shall use the procedures specified in paragraphs (i)(2)(i) and 
(ii) or (iii) of this section to determine the organic HAP and VOC 
emission levels of the alternative application technique as compared to 
either HVLP or electrostatic spray application methods.
* * * * *
    (k) Organic HAP content level determination--compliant chemical 
milling maskants. For those uncontrolled chemical milling maskants 
complying with the chemical milling maskant organic HAP content limit 
specified in Sec.  63.747(c)(1) without being averaged, the procedure 
in paragraph (k)(1) of this section shall be used to determine the mass 
of organic HAP emitted per unit volume of coating (chemical milling 
maskant) i as applied (less water), Hi (lb/gal). As an 
alternative

[[Page 8435]]

to the procedures in paragraph (k)(1) of this section, an owner or 
operator may use coating manufacturer's supplied data to demonstrate 
that organic HAP emitted per volume of coating (less water), as 
applied, is less than or equal to the applicable organic HAP limit 
specified in Sec.  63.747(c).
* * * * *
    (m) VOC content level determination--compliant chemical milling 
maskants. For those uncontrolled chemical milling maskants complying 
with the chemical milling maskant VOC content limit specified in Sec.  
63.747(c)(2) without being averaged, the procedure specified in 
paragraphs (m)(1) and (2) of this section shall be used to determine 
the mass of VOC emitted per volume of chemical milling maskant (less 
water and exempt solvents) as applied. As an alternative to the 
procedures in paragraphs (m)(1) and (2) of this section, an owner or 
operator may use coating manufacturer's supplied data to demonstrate 
that VOC emitted per volume of coating (less water and exempt 
solvents), as applied, is less than or equal to the applicable VOC 
limit specified in Sec.  63.747(c).
* * * * *
    (o) Inorganic HAP emissions--dry particulate filter certification 
requirements. Dry particulate filters used to comply with Sec.  
63.745(g)(2) or Sec.  63.746(b)(4) must be certified by the filter 
manufacturer or distributor, paint/depainting booth supplier and/or the 
facility owner or operator using method 319 in appendix A of this part, 
to meet or exceed the efficiency data points found in Tables 2 and 3 or 
4 and 5 of Sec.  63.745 for existing or new sources respectively.
0
10. Section 63.751 is amended by revising paragraph (c) to read as 
follows:


Sec.  63.751  Monitoring requirements.

* * * * *
    (c) Dry particulate filter, HEPA filter and waterwash systems--
primer, topcoat and specialty coating application operations. (1) Each 
owner or operator using a dry particulate filter system to meet the 
requirements of Sec.  63.745(g)(2) shall, while primer, topcoat and 
specialty coating application operations are occurring, continuously 
monitor the pressure drop across the system and read and record the 
pressure drop once per shift following the recordkeeping requirements 
of Sec.  63.752(d).
    (2) Each owner or operator using a conventional waterwash system to 
meet the requirements of Sec.  63.745(g)(2) shall, while primer or 
topcoat application operations are occurring, continuously monitor the 
water flow rate through the system and read and record the water flow 
rate once per shift following the recordkeeping requirements of Sec.  
63.752(d). Each owner or operator using a pumpless waterwash system to 
meet the requirements of Sec.  63.745(g)(2) shall, while primer, 
topcoat and specialty coating application operations are occurring, 
measure and record the parameter(s) recommended by the booth 
manufacturer that indicate booth performance once per shift, following 
the recordkeeping requirements of Sec.  63.752(d).
* * * * *
0
11. Section 63.752 is amended by:
0
a. Revising paragraph (a);
0
b. Revising paragraphs (c) introductory text, (c)(1), (c)(2) 
introductory text, (c)(4) introductory text, (c)(5) introductory text 
and (c)(6) introductory text;
0
c. Revising paragraphs (d) paragraph heading and (d)(1); and
0
d. Revising paragraph (f) introductory text.
    The revisions read as follows:


Sec.  63.752  Recordkeeping requirements.

    (a) General. Each owner or operator of a source subject to this 
subpart shall fulfill all recordkeeping requirements specified in Sec.  
63.10 (a), (b), (d) and (f), except Sec.  63.10(b)(2)(i), (iv), and 
(v). Each owner or operator must also record and maintain according to 
Sec.  63.10(b)(1) the information specified in paragraph (a)(1) through 
(3) of this section.
    (1) In the event that an affected unit fails to meet an applicable 
standard, record the number of failures. For each failure record the 
date, time and duration of each failure.
    (2) For each failure to meet an applicable standard, record and 
retain a list of the affected sources or equipment, an estimate of the 
quantity of each regulated pollutant emitted over any emission limit 
and a description of the method used to estimate the emissions.
    (3) Record actions taken to minimize emissions in accordance with 
Sec.  63.743(e), and any corrective actions taken to return the 
affected unit to its normal or usual manner of operation.
* * * * *
    (c) Primer, topcoat and specialty coating application operations--
organic HAP and VOC. Each owner or operator required to comply with the 
organic HAP and VOC content limits specified in Sec.  63.745(c) shall 
record the information specified in paragraphs (c)(1) through (6) of 
this section, as appropriate. Each owner and operator using coating 
manufacturer's supplied data to demonstrate compliance with the 
applicable organic HAP or VOC limit specified in Sec.  63.745(c) may 
retain the manufacturer's documentation and annual purchase records in 
place of the records specified in paragraphs (c)(2) and (3) of this 
section.
    (1) The name and VOC content as received and as applied of each 
primer, topcoat and specialty coating used at the facility.
    (2) For uncontrolled primers, topcoats and specialty coatings that 
meet the organic HAP and VOC content limits in Sec.  63.745(c)(1) 
through (6) without averaging:
* * * * *
    (4) For primers, topcoats and specialty coatings complying with the 
organic HAP or VOC content level by averaging:
* * * * *
    (5) For primers, topcoats and specialty coatings that are 
controlled by a control device other than a carbon adsorber:
* * * * *
    (6) For primers, topcoats and specialty coatings that are 
controlled by a carbon adsorber:
* * * * *
    (d) Primer, topcoat and specialty coating application operations--
inorganic HAP emissions. (1) Each owner or operator complying with 
Sec.  63.745(g) for the control of inorganic HAP emissions from primer, 
topcoat and specialty coating application operations through the use of 
a dry particulate filter system or a HEPA filter system shall record 
the pressure drop across the operating system once each shift during 
which coating operations occur.
    (f) Chemical milling maskant application operations. Each owner or 
operator seeking to comply with the organic HAP and VOC content limits 
for the chemical milling maskant application operation, as specified in 
Sec.  63.747(c), or the control system requirements specified in Sec.  
63.747(d), shall record the information specified in paragraphs (f)(1) 
through (4) of this section, as appropriate. Each owner and operator 
using coating manufacturer's supplied data to demonstrate compliance 
with the applicable organic HAP or VOC limit specified in Sec.  
63.747(c) may retain the manufacturer's documentation and annual 
purchase records in place of the records specified in paragraph (f)(1) 
of this section.
* * * * *
0
12. Section 63.753 is amended by:
0
a. Revising paragraph (a)(1) introductory text and (a)(2);
0
b. Adding paragraphs (a)(4) and (5);
0
c. Revising paragraphs (c) introductory text, (c)(1)(i) and (ii).

[[Page 8436]]

0
d. Revising paragraph (e)(1).
    The revisions and additions read as follows:


Sec.  63.753  Reporting requirements.

    (a)(1) Except as provided in paragraphs (a)(2) through (5) of this 
section, each owner or operator subject to this subpart shall fulfill 
the requirements contained in Sec.  63.9(a) through (e) and (h) through 
(j), Notification requirements and Sec.  63.10(a), (b), (d) and (f), 
Recordkeeping and reporting requirements, of the General Provisions, 40 
CFR part 63, subpart A and that the initial notification for existing 
sources required in Sec.  63.9(b)(2) shall be submitted not later than 
September 1, 1997, or as specified in Sec.  63.9(b)(2). In addition to 
the requirements of Sec.  63.9(h), the notification of compliance 
status shall include:
* * * * *
    (2) The initial notification for existing sources, required in 
Sec.  63.9(b)(2) shall be submitted no later than September 1, 1997, or 
as specified in Sec.  63.9(b)(2). For the purposes of this subpart, a 
title V or part 70 permit application may be used in lieu of the 
initial notification required under Sec.  63.9(b)(2), provided the same 
information is contained in the permit application as required by Sec.  
63.9(b)(2), and the State to which the permit application has been 
submitted has an approved operating permit program under part 70 of 
this chapter and has received delegation of authority from the EPA. 
Permit applications shall be submitted by the same due dates as those 
specified for the initial notifications.
* * * * *
    (4) Each owner or operator subject to this subpart is not required 
to comply with Sec.  63.10(b)(2)(i), (b)(2)(iv), (b)(2)(v), and (d)(5).
    (5) If a source fails to meet an applicable standard specified in 
Sec. Sec.  63.744 through 63.748, report such events in the semiannual 
report:
    (i) The number of failures to meet an applicable standard.
    (ii) For each instance, report the date, time and duration of each 
failure.
    (iii) For each failure the report must include a list of the 
affected sources or equipment, an estimate of the quantity of each 
regulated pollutant emitted over any emission limit and a description 
of the method used to estimate the emissions.
* * * * *
    (c) Primer, topcoat and specialty coating application operations. 
Each owner or operator of a primer or topcoat application operation 
subject to this subpart shall submit the following information:
    (1) * * *
    (i) For primers, topcoats and specialty coatings where compliance 
is not being achieved through the use of averaging or a control device, 
the HAP or VOC content in manufacturer's supplied data as recorded 
under Sec.  63.752(c), or each value of Hi and Gi 
as recorded under Sec.  63.752(c)(2)(i), that exceeds the applicable 
organic HAP or VOC content limit specified in Sec.  63.745(c);
    (ii) For primers, topcoats and specialty coatings where compliance 
is being achieved through the use of averaging, each value of 
Ha and Ga, as recorded under Sec.  
63.752(c)(4)(i), that exceeds the applicable organic HAP or VOC content 
limit specified in Sec.  63.745(c);
* * * * *
    (e) * * *
    (1) For chemical milling maskants where compliance is not being 
achieved through the use of averaging or a control device, the HAP or 
VOC content in manufacturer's supplied data as recorded under Sec.  
63.752(f), or each value of Hi and Gi as recorded 
under Sec.  63.752(f)(1)(i), that exceeds the applicable organic HAP or 
VOC content limit specified in Sec.  63.747(c);
* * * * *
0
13. Revise Table 1 to Subpart GG of Part 63 to read as follows:

  Table 1 to Subpart GG of Part 63--General Provisions Applicability to
                               Subpart GG
------------------------------------------------------------------------
                                    Applies to
           Reference             affected sources         Comment
                                  in subpart GG
------------------------------------------------------------------------
63.1(a)(1)....................  Yes.               .....................
63.1(a)(2)....................  Yes.               .....................
63.1(a)(3)....................  Yes.               .....................
63.1(a)(4)....................  Yes.               .....................
63.1(a)(5)....................  No...............  Reserved.
63.1(a)(6)....................  Yes.               .....................
63.1(a)(7)....................  Yes.               .....................
63.1(a)(8)....................  Yes.               .....................
63.1(a)(9)....................  No...............  Reserved.
63.1(a)(10)...................  Yes.               .....................
63.1(a)(11)...................  Yes.               .....................
63.1(a)(12)...................  Yes.               .....................
63.1(a)(13)...................  Yes.               .....................
63.1(a)(14)...................  Yes.               .....................
63.1(b)(1)....................  Yes.               .....................
63.1(b)(2)....................  Yes.               .....................
63.1(b)(3)....................  Yes.               .....................
63.1(c)(1)....................  Yes.               .....................
63.1(c)(2)....................  Yes..............  Subpart GG does not
                                                    apply to area
                                                    sources.
63.1(c)(3)....................  No...............  Reserved.
63.1(c)(4)....................  Yes.               .....................
63.1(c)(5)....................  Yes.               .....................
63.1(d).......................  No...............  Reserved.
63.1(e).......................  Yes.               .....................
63.2..........................  Yes.               .....................
63.3..........................  Yes.               .....................
63.4(a)(1)....................  Yes.               .....................
63.4(a)(2)....................  Yes.               .....................
63.4(a)(3)....................  Yes.               .....................
63.4(a)(4)....................  No...............  Reserved.
63.4(a)(5)....................  Yes.               .....................

[[Page 8437]]

 
63.4(b).......................  Yes.               .....................
63.4(c).......................  Yes.               .....................
63.5(a).......................  Yes.               .....................
63.5(b)(1)....................  Yes.               .....................
63.5(b)(2)....................  No...............  Reserved.
63.5(b)(3)....................  Yes.               .....................
63.5(b)(4)....................  Yes.               .....................
63.5(b)(5)....................  Yes.               .....................
63.5(b)(6)....................  Yes.               .....................
63.5(c).......................  No...............  Reserved.
63.5(d)(1)(i).................  Yes.               .....................
63.5(d)(1)(ii)(A) through (H).  Yes.               .....................
63.5(d)(1)(ii)(I).............  No...............  Reserved.
63.5(d)(1)(ii)(J).............  Yes.               .....................
63.5(d)(1)(iii)...............  Yes.               .....................
63.5(d)(2) through (4)........  Yes.               .....................
63.5(e).......................  Yes.               .....................
63.5(f).......................  Yes.               .....................
63.6(a).......................  Yes.               .....................
63.6(b)(1) through (5)........  Yes..............  Sec.   63.749(a)
                                                    specifies compliance
                                                    dates for new
                                                    sources.
63.6(b)(6)....................  No...............  Reserved.
63.6(b)(7)....................  Yes.               .....................
63.6(c)(1)....................  Yes.               .....................
63.6(c)(2)....................  No...............  The standards in
                                                    subpart GG are
                                                    promulgated under
                                                    section 112(d) of
                                                    the CAA.
63.6(c)(3) and (4)............  No...............  Reserved.
63.6(c)(5)....................  Yes.               .....................
63.6(d).......................  No...............  Reserved.
63.6(e)(1)(i).................  No...............  See Sec.   63.743(e)
                                                    for general duty
                                                    requirement.
63.6(e)(1)(ii)................  No.                .....................
63.6(e)(2)....................  No...............  Section reserved.
63.6(e)(3)....................  No.                .....................
63.6(f)(1)....................  No.                .....................
63.6(f)(2) and (3)............  Yes.               .....................
63.6(g).......................  Yes.               .....................
63.6(h).......................  No...............  The standards in
                                                    subpart GG do not
                                                    include opacity
                                                    standards.
63.6(i)(1) and (3)............  Yes.               .....................
63.6(i)(4)(i)(A)..............  Yes.               .....................
63.6(i)(4)(i)(B)..............  No...............  Sec.   63.743(a)(4)
                                                    specifies that
                                                    requests for
                                                    extension of
                                                    compliance must be
                                                    submitted no later
                                                    than 120 days before
                                                    an affected source's
                                                    compliance date.
63.6(i)(4)(ii)................  No...............  The standards in
                                                    subpart GG are
                                                    promulgated under
                                                    section 112(d) of
                                                    the CAA.
63.6(i)(5) through (12).......  Yes.               .....................
63.6(i)(13)...................  Yes.               .....................
63.6(i)(14)...................  Yes.               .....................
63.6(i)(15)...................  No...............  Reserved.
63.6(i)(16)...................  Yes.               .....................
63.6(j).......................  Yes.               .....................
63.7(a)(1)....................  Yes.               .....................
63.7(a)(2)(i) through (vi)....  Yes.               .....................
63.7(a)(2)(vii) and (viii)....  No...............  Reserved.
63.7(a)(2)(ix)................  Yes.               .....................
63.7(a)(3)....................  Yes.               .....................
63.7(b).......................  Yes.               .....................
63.7(c).......................  Yes.               .....................
63.7(d).......................  Yes.               .....................
63.7(e)(1)....................  No...............  See Sec.   63.749(j).
63.7(e)(2) through (4)........  Yes.               .....................
63.7(f).......................  Yes.               .....................
63.7(g)(1)....................  Yes.               .....................
63.7(g)(2)....................  No...............  Reserved.
63.7(g)(3)....................  Yes.               .....................
63.7(h).......................  Yes.               .....................
63.8(a)(1) and (2)............  Yes.               .....................
63.8(a)(3)....................  No...............  Reserved.
63.8(a)(4)....................  Yes.               .....................
63.8(b).......................  Yes.               .....................
63.8(c)(1)(i).................  No.                .....................

[[Page 8438]]

 
63.8(c)(1)(ii)................  Yes.               .....................
63.8(c)(1)(iii)...............  No.                .....................
63.8(c)(2) through (d)(2).....  Yes.               .....................
63.8(d)(3)....................  No.                .....................
63.8(e)(1) through (4)........  Yes.               .....................
63.8(e)(5)(i).................  Yes.               .....................
63.8(e)(5)(ii)................  No...............  The standards in
                                                    subpart GG do not
                                                    include opacity
                                                    standards.
63.8(f)(1)....................  Yes.               .....................
63.8(f)(2)(i) through (vii)...  Yes.               .....................
63.8(f)(2)(viii)..............  No...............  The standards in
                                                    subpart GG do not
                                                    include opacity
                                                    standards.
63.8(f)(2)(ix)................  Yes.               .....................
63.8(f)(3) through (6)........  Yes.               .....................
63.8(g).......................  Yes.               .....................
63.9(a).......................  Yes.               .....................
63.9(b)(1)....................  Yes.               .....................
63.9(b)(2)....................  Yes..............  Sec.   63.753(a)(1)
                                                    requires submittal
                                                    of the initial
                                                    notification at
                                                    least 1 year prior
                                                    to the compliance
                                                    date; Sec.
                                                    63.753(a)(2) allows
                                                    a title V or part 70
                                                    permit application
                                                    to be substituted
                                                    for the initial
                                                    notification in
                                                    certain
                                                    circumstances.
63.9(b)(3)....................  Yes.               .....................
63.9(b)(4)....................  Yes.               .....................
63.9(b)(5)....................  Yes.               .....................
63.9(c).......................  Yes.               .....................
63.9(d).......................  Yes.               .....................
63.9(e).......................  Yes.               .....................
63.9(f).......................  No...............  The standards in
                                                    subpart GG do not
                                                    include opacity
                                                    standards.
63.9(g)(1)....................  No.                .....................
63.9(g)(2)....................  No...............  The standards in
                                                    subpart GG do not
                                                    include opacity
                                                    standards.
63.9(g)(3)....................  No.                .....................
63.9(h)(1) through (3)........  Yes..............  Sec.   63.753(a)(1)
                                                    also specifies
                                                    additional
                                                    information to be
                                                    included in the
                                                    notification of
                                                    compliance status.
63.9(h)(4)....................  No...............  Reserved.
63.9(h)(5) and (6)............  Yes.               .....................
63.9(i).......................  Yes.               .....................
63.9(j).......................  Yes.               .....................
63.10(a)......................  Yes.               .....................
63.10(b)(1)...................  Yes.               .....................
63.10(b)(2)(i)................  No.                .....................
63.10(b)(2)(ii)...............  No...............  See Sec.   63.752(a)
                                                    for recordkeeping
                                                    of: (1) Date, time
                                                    and duration; (2)
                                                    Listing of affected
                                                    source or equipment
                                                    and an estimate of
                                                    the quantity of each
                                                    regulated pollutant
                                                    emitted over the
                                                    standard; and (3)
                                                    Actions to minimize
                                                    emissions and
                                                    correct the failure.
63.10(b)(2)(iii)..............  Yes.               .....................
63.10(b)(2)(iv) and (v).......  No.                .....................
63.10(b)(2)(vi)...............  Yes.               .....................
63.10(b)(2)(vi)(A) through (C)  No...............  Sec.
                                                    63.10(b)(vii)(A),
                                                    (B) and (C) do not
                                                    apply because
                                                    subpart GG does not
                                                    require the use of
                                                    CEMS.
63.10(b)(2)(vii) through (xiv)
63.10(b)(3)...................  Yes.               .....................
63.10(c)(1)...................  No.                .....................
63.10(c)(2) through (4).......  No...............  Reserved.
63.10(c)(5) and (6)...........  No.                .....................
63.10(c)(7) and (8)...........  Yes.               .....................
63.10(c)(9)...................  No...............  Reserved.
63.10(c)(10) through (13).....  No.                .....................
63.10(c)(14)..................  No...............  Sec.   63.8(d) does
                                                    not apply to this
                                                    subpart.
63.10(c)(15)..................  No.                .....................
63.10(d)(1) and (2)...........  Yes.               .....................
63.10(d)(3)...................  No...............  The standards in
                                                    subpart GG do not
                                                    include opacity
                                                    standards.
63.10(d)(4)...................  Yes.               .....................
63.10(d)(5)...................  No. See Sec.       .....................
                                 63.753 (a)(5)
                                 for malfunction
                                 reporting
                                 requirements..
63.(10)(e)(1).................  No.                .....................

[[Page 8439]]

 
63.10(e)(2)(i)................  No.                .....................
63.10(e)(2)(ii)...............  No...............  The standards in
                                                    subpart GG do not
                                                    include opacity
                                                    standards.
63.10(e)(3)...................  No.                .....................
63.10(e)(4)...................  No...............  The standards in
                                                    subpart GG do not
                                                    include opacity
                                                    standards.
63.10(f)......................  Yes.               .....................
63.11.........................  Yes.               .....................
63.12.........................  Yes.               .....................
63.13.........................  Yes.               .....................
63.14.........................  Yes.               .....................
63.15.........................  Yes.               .....................
63.16.........................  Yes.
------------------------------------------------------------------------


[FR Doc. 2015-02055 Filed 2-13-15; 8:45 am]
BILLING CODE 6560-50-P