Vol. 79 Monday, 

No. 235 December 8, 2014 

Part III 

Environmental Protection Agency 

40 CFR Part 63 

National Emissions Standards for Hazardous Air Pollutants: Secondary 

Aluminum Production; Proposed Rule 

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72874 Federal Register / Vol. 79, No. 235 / Monday, December 8, 2014 / Proposed Rules 

ENVIRONMENTAL PROTECTION 

AGENCY 

40 CFR Part 63 

[EPA–HQ–OAR–2010–0544; FRL–9919–33– 

OAR] 

RIN 2060–AQ40 

National Emissions Standards for 

Hazardous Air Pollutants: Secondary 

Aluminum Production 

AGENCY: Environmental Protection 

Agency. 

ACTION: Supplemental notice of 

proposed rulemaking. 

SUMMARY: This action supplements our 

notice of proposed rulemaking for the 

national emissions standards for 

hazardous air pollutants (NESHAP) for 

secondary aluminum production, which 

was published in the Federal Register 

on February 14, 2012. In that action, the 

Environmental Protection Agency (EPA) 

proposed decisions concerning the 

residual risk and technology review for 

the Secondary Aluminum Production 

source category and proposed 

amendments to correct and clarify rule 

requirements. This supplemental 

proposal presents a revised risk review 

(including a revised inhalation risk 

assessment, a refined multipathway risk 

assessment, and an updated ample 

margin of safety analysis) and a revised 

technology review for the Secondary 

Aluminum Production source category. 

Similar to the 2012 proposal, we found 

risks due to emissions of air toxics to be 

acceptable from this source category and 

we identified no cost effective controls 

under the updated ample margin of 

safety analysis or the technology review 

to achieve further emissions reductions. 

Therefore, we are proposing no 

revisions to the numeric emission 

standards based on these revised 

analyses. However, this supplemental 

proposal supplements and modifies 

several of the proposed technical 

corrections and rule clarifications that 

were originally presented in the 

February 14, 2012 proposal; withdraws 

our previous proposal to include 

affirmative defense provisions in the 

regulation; proposes alternative 

compliance options for the operating 

and monitoring requirements for sweat 

furnaces; and provides a revised cost 

analysis for compliance testing. This 

action, if finalized, would result in 

improved monitoring, compliance and 

implementation of the rule. 

DATES: Comments. Comments must be 

received on or before January 22, 2015. 

A copy of comments on the information 

collection provisions should be 

submitted to the Office of Management 

and Budget (OMB) on or before January 

7, 2015. 

Public Hearing. If anyone contacts the 

EPA requesting a public hearing by 

December 15, 2014, the EPA will hold 

a public hearing on December 23, 2014 

at the U.S. EPA building at 109 T.W. 

Alexander Drive, Research Triangle 

Park, NC 27711. If you are interested in 

requesting a public hearing or attending 

the public hearing, contact Ms. Virginia 

Hunt at (919) 541–0832 or at 

hunt.virginia@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–2010–0544, by one of 

the following methods: 

• Federal eRulemaking Portal: http:// 

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–2010–0544 in the subject line 

of the message. 

• Fax: (202) 566–9744, Attention 

Docket ID No. EPA–HQ–OAR–2010– 

0544. 

• Mail: Environmental Protection 

Agency, EPA Docket Center (EPA/DC), 

Mail Code 28221T, Attention Docket ID 

No. EPA–HQ–OAR–2010–0544, 1200 

Pennsylvania Avenue NW., Washington, 

DC 20460. 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–2010– 

0544. 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–2010– 

0544. 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 http:// 

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 http://

www.regulations.gov or email. The 

http://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 http://

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 http:// 

www.epa.gov/dockets. 

Docket: The EPA has established a 

docket for this rulemaking under Docket 

ID No. EPA–HQ–OAR–2010–0544. All 

documents in the docket are listed in 

the www.regulations.gov index. 

Although listed in the index, some 

information is not publicly available, 

e.g., CBI or other information whose 

disclosure is restricted by statute. 

Certain other material, such as 

copyrighted material, is not placed on 

the Internet and will be publicly 

available only in hard copy. Publicly 

available docket materials are available 

either electronically in http://

www.regulations.gov or in hard copy at 

the EPA Docket Center, 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 anyone contacts the 

EPA requesting a public hearing by 

December 15, 2014, the public hearing 

will be held on December 23, 2014 at 

the EPA’s campus at 109 T.W. 

Alexander Drive, Research Triangle 

Park, North Carolina. The hearing will 

begin at 1:00 p.m. (Eastern Standard 

Time) and conclude at 5:00 p.m. 

(Eastern Standard Time). Please contact 

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Ms. Virginia Hunt at 919–541–0832 or at 

hunt.virginia@epa.gov to register to 

speak at the hearing or to inquire as to 

whether or not a hearing will be held. 

The last day to pre-register in advance 

to speak at the hearing will be December 

22, 2014. 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 accommodated. 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 accommodations 

without advance notice. 

If no one contacts the EPA requesting 

a public hearing to be held concerning 

this proposed rule by December 15, 

2014, 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 supplemental 

notice of proposed rulemaking. The EPA 

will make every effort to accommodate 

all speakers who arrive and register. 

Because the hearing will be held at a 

U.S. government 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. Hunt if they will need 

specific equipment, or if there are other 

special needs related to providing 

comments at the hearings. Verbatim 

transcripts of the hearing 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. Please 

contact Ms. Virginia Hunt at (919) 541– 

0832 or at hunt.virginia@epa.gov to 

request or register to speak at the 

hearing or to inquire as to whether or 

not a hearing will be held. 

FOR FURTHER INFORMATION CONTACT: For 

questions about this proposed action, 

contact Ms. Rochelle Boyd, 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 

(919) 541–1390; fax number: (919) 541– 

3207; and email address: boyd.rochelle@

epa.gov. For specific information 

regarding the risk modeling 

methodology, contact James Hirtz, 

Health and Environmental Impacts 

Division, (C539–02), Office of Air 

Quality Planning and Standards, U.S. 

Environmental Protection Agency, 

Research Triangle Park, NC 27711; 

telephone number: (919) 541–0881; fax 

number: (919) 541–0840; and email 

address: hirtz.james@epa.gov. For 

information about the applicability of 

the NESHAP to a particular entity, 

contact Scott Throwe, Office of 

Enforcement and Compliance Assurance 

(OECA), telephone number (202) 564– 

7013; and email address: throwe.scott@

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: 

ACGIH American Conference of 

Government Industrial Hygienists 

AEGL acute exposure guideline levels 

AERMOD air dispersion model used by the 

HEM–3 model 

AMOS ample margin of safety 

ATSDR Agency for Toxic Substances and 

Disease Registry 

BACT best available control technology 

CAA Clean Air Act 

CalEPA California Environmental 

Protection Agency 

CBI confidential business information 

CFR Code of Federal Regulations 

D/F dioxins and furans 

EJ environmental justice 

EPA United States Environmental 

Protection Agency 

ERPG Emergency Response Planning 

Guidelines 

ERT Electronic Reporting Tool 

HAP hazardous air pollutants 

HCl hydrogen chloride 

HEM–3 Human Exposure Model, Version 3 

HF hydrogen fluoride 

HI hazard index 

HQ hazard quotient 

ICR information collection request 

IRIS Integrated Risk Information System 

km kilometer 

lb/yr pounds per year 

LOAEL lowest-observed-adverse-effect level 

MACT maximum achievable control 

technology 

mg/m3 milligrams per cubic meter 

MIR maximum individual risk 

NAAQS National Ambient Air Quality 

Standard 

NAICS North American Industry 

Classification System 

NAS National Academy of Sciences 

NATA National Air Toxics Assessment 

NEI National Emissions Inventory 

NESHAP National Emissions Standards for 

Hazardous Air Pollutants 

NOAEL no observed adverse effects level 

NRC National Research Council 

NTTAA National Technology Transfer and 

Advancement Act 

O&M operation and maintenance 

OAQPS Office of Air Quality Planning and 

Standards 

OECA Office of Enforcement and 

Compliance Assurance 

OMB Office of Management and Budget 

OM&M operation, maintenance and 

monitoring 

PAH polycyclic aromatic hydrocarbons 

PB–HAP hazardous air pollutants known to 

be persistent and bio-accumulative in the 

environment 

PEL probable effect levels 

PM particulate matter 

POM polycyclic organic matter 

REL reference exposure level 

RFA Regulatory Flexibility Act 

RfC reference concentration 

RfD reference dose 

RTR residual risk and technology review 

SAB Science Advisory Board 

SAPU secondary aluminum processing unit 

SBA Small Business Administration 

SOP standard operating procedures 

SSM startup, shutdown, and malfunction 

TEQ toxic equivalents 

THC total hydrocarbons 

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 

UBC used beverage containers 

UF uncertainty factor 

mg/m3 microgram per cubic meter 

UMRA Unfunded Mandates Reform Act 

URE unit risk estimate 

WHO World Health Organization 

Organization of this Document. The 

information in this preamble is 

organized as follows: 

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72876 Federal Register / Vol. 79, No. 235 / Monday, December 8, 2014 / Proposed Rules 

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 Information 

A. What is the statutory authority for this 

action? 

B. What is this source category and how 

does the current NESHAP regulate its 

HAP emissions? 

C. What is the history of the Secondary 

Aluminum Risk and Technology 

Review? 

D. What data collection activities were 

conducted to support this action? 

III. Analytical Procedures 

A. How did we evaluate the post-MACT 

risks posed by the Secondary Aluminum 

Production source category in the risk 

assessment developed for this 

supplemental proposal? 

B. How did we consider the risk results in 

making decisions for this supplemental 

proposal? 

C. How did we perform the technology 

review? 

IV. Revised Analytical Results and Proposed 

Decisions for the Secondary Aluminum 

Production Source Category 

A. What are the results of the risk 

assessment and analysis? 

B. What are our proposed decisions 

regarding risk acceptability, ample 

margin of safety and adverse 

environmental effects based on our 

revised analyses? 

C. What are the results and proposed 

decisions based on our technology 

review? 

D. What other actions are we proposing? 

E. What compliance dates are we 

proposing? 

V. Summary of the Revised 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 

D. Unfunded Mandates Reform Act 

E. Executive Order 13132: Federalism 

F. Executive Order 13175: Consultation 

and Coordination with Indian Tribal 

Governments 

G. Executive Order 13045: Protection of 

Children from Environmental Health 

Risks and Safety Risks 

H. Executive Order 13211: Actions 

Concerning Regulations That 

Significantly Affect Energy Supply, 

Distribution, or Use 

I. National Technology Transfer and 

Advancement Act 

J. Executive Order 12898: Federal Actions 

to Address Environmental Justice in 

Minority Populations and Low-Income 

Populations 

I. General Information 

A. Does this action apply to me? 

The regulated industrial source 

category that is the subject of this 

supplemental proposal is listed in Table 

1 of this preamble. Table 1 of this 

preamble is not intended to be 

exhaustive, but rather provides a guide 

for readers regarding the entities likely 

to be affected by this proposed action. 

These standards, once finalized, will be 

directly applicable to affected sources. 

Federal, state, local and tribal 

government entities are not affected by 

this proposed action. To determine 

whether your facility would be affected, 

you should examine the applicability 

criteria in the NESHAP. The Secondary 

Aluminum Production source category 

includes any facility using clean charge, 

aluminum scrap or dross from 

aluminum production, as the raw 

material and performing one or more of 

the following processes: scrap 

shredding, scrap drying/delacquering/

decoating, thermal chip drying, furnace 

operations (i.e., melting, holding, 

sweating, refining, fluxing or alloying), 

recovery of aluminum from dross, inline fluxing or dross cooling. 

TABLE 1—NESHAP AND INDUSTRIAL SOURCE CATEGORIES AFFECTED BY THIS PROPOSED ACTION

Industrial source category NESHAP NAICS 

Code a

Secondary Aluminum Production ............................................................................................................ Secondary .............................. 331314 

Primary Aluminum Production Facilities ................................................................................................. Aluminum ............................... 331312 

Aluminum Sheet, Plate, and Foil Manufacturing Facilities ..................................................................... Production .............................. 331315 

Aluminum Extruded Product Manufacturing Facilities ............................................................................ ................................................ 331316 

Other Aluminum Rolling and Drawing Facilities ..................................................................................... ................................................ 331319 

Aluminum Die Casting Facilities ............................................................................................................. ................................................ 331521 

Aluminum Foundry Facilities ................................................................................................................... ................................................ 331524 

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 

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 

supplemental proposal at: http://

www.epa.gov/ttn/atw/alum2nd/

alum2pg.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: http://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 http://www.regulations.gov or 

email. Clearly mark the part or all of the 

information that you claim to be CBI. 

For CBI information on a disk or CD– 

ROM that you mail to the EPA, mark the 

outside of the disk or CD–ROM as CBI 

and then identify electronically within 

the disk or CD–ROM the specific 

information that is claimed as CBI. In 

addition to one complete version of the 

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: Roberto 

Morales, OAQPS Document Control 

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Federal Register / Vol. 79, No. 235 / Monday, December 8, 2014 / Proposed Rules 72877 

Officer (C404–02), OAQPS, U.S. 

Environmental Protection Agency, 

Research Triangle Park, North Carolina 

27711, Attention Docket ID No. EPA– 

HQ–OAR–2010–0544. 

II. Background Information 

A. What is the statutory authority for 

this action? 

Section 112 of the Clean Air Act 

(CAA) establishes a two-stage regulatory 

process to address emissions of 

hazardous air pollutants (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 

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 emission 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 bestcontrolled 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 eight 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). 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 

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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. CAA section 112(a)(7). 

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 riskfree. 

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 at 38045. 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 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 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 coemission 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 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 noncancer 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 at 

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. 

The CAA does not specifically define 

the terms ‘‘individual most exposed,’’ 

‘‘acceptable level’’ and ‘‘ample margin 

of safety.’’ In the Benzene NESHAP, 54 

FR at 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 

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associated with standards more 

stringent than the MACT standard or a 

more stringent standard that the 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. 

B. What is this source category and how 

does the current NESHAP regulate its 

HAP emissions? 

The Secondary Aluminum Production 

source category includes facilities that 

produce aluminum from scrap 

aluminum material and consists of the 

following operations: (1) Preprocessing 

of scrap aluminum, including size 

reduction and removal of oils, coatings 

and other contaminants; (2) furnace 

operations, including melting, infurnace refining, fluxing and tapping; 

(3) additional refining, by means of inline fluxing; and (4) cooling of dross. 

The following sections include 

descriptions of the affected sources in 

the Secondary Aluminum Production 

source category, the origin of HAP 

emissions from these affected sources 

and factors affecting the emissions. 

Scrap aluminum is often preprocessed 

prior to melting. Preprocessing steps 

may include shredding to reduce the 

size of aluminum scrap; drying of oily 

scrap such as machine turnings and 

borings; and/or heating in a scrap dryer, 

delacquering kiln or decoating kiln to 

remove coatings or other contaminants 

that may be present on the scrap. 

Heating of high iron content scrap in a 

sweat furnace to reclaim the aluminum 

content is also a preprocessing 

operation. 

Crushing, shredding and grinding 

operations are used to reduce the size of 

scrap aluminum. Particulate matter 

(PM) and HAP metals emissions are 

generated as dust from coatings and 

other contaminants contained in the 

scrap aluminum. 

A chip dryer is used to evaporate oil 

and/or moisture from uncoated 

aluminum chips and borings. Chip 

dryers typically operate at temperatures 

ranging between 150 °C to 400 °C (300 

°F to 750 °F). An uncontrolled chip 

dryer may emit dioxins and furans (D/ 

F) and total hydrocarbons (THC), of 

which some fraction is organic HAP. 

Painted and/or coated materials are 

processed in a scrap dryer/delacquering 

kiln/decoating kiln to remove coatings 

and other contaminants that may be 

present in the scrap prior to melting. 

Coatings, oils, grease and lubricants 

represent up to 20 percent of the total 

weight of these materials. Organic HAP, 

D/F and inorganic HAP including 

particulate metal HAP are emitted 

during the drying/delacquering/

decoating process. 

Used beverage containers (UBC) 

comprise a major portion of the recycled 

aluminum scrap used as feedstock by 

the industry. In scrap drying/

delacquering/decoating operations, UBC 

and other post-consumer coated 

products (e.g., aluminum siding) are 

heated to an exit temperature of up to 

540 °C (1,000 °F) to volatilize and 

remove various organic contaminants 

such as paints, oils, lacquers, rubber and 

plastic laminates prior to melting. An 

uncontrolled scrap dryer/delacquering 

kiln/decoating kiln emits PM (of which 

some fraction is particulate metal HAP), 

hydrogen chloride (HCl), THC (of which 

some fraction is organic HAP) and D/F. 

A sweat furnace is typically used to 

reclaim (or ‘‘sweat’’) the aluminum from 

scrap with high levels of iron. These 

furnaces operate in batch mode at a 

temperature that is high enough to melt 

the aluminum, but not high enough to 

melt the iron. The aluminum melts and 

flows out of the furnace while the iron 

remains in the furnace in solid form. 

The molten aluminum can be cast into 

sows, ingots or T-bars that are used as 

feedstock for aluminum melting and 

refining furnaces. Alternately, molten 

aluminum can be fed directly to a 

melting or refining furnace. An 

uncontrolled sweat furnace may emit 

D/F. 

Process (i.e., melting, holding or 

refining) furnaces are refractory-lined 

metal vessels heated by an oil or gas 

burner to achieve a metal temperature of 

about 760 °C (1,400 °F). The melting 

process begins with the charging of 

scrap into the furnace. A gaseous 

(typically, chlorine) or salt flux may be 

added to remove impurities and reduce 

aluminum oxidation. Once molten, the 

chemistry of the bath is adjusted by 

adding selected scrap or alloying agents, 

such as silicon. Salt and other fluxes 

contain chloride and fluoride 

compounds that may be released when 

introduced to the bath. HCl may also be 

released when chlorine-containing 

contaminants (such as polyvinyl 

chloride coatings) present in some types 

of scrap are introduced to the bath. 

Argon and nitrogen fluxes are not 

reactive and do not produce HAP. In a 

sidewell melting furnace, fluxing is 

performed in the sidewell, and fluxing 

emissions from the sidewell are 

controlled. In this type of furnace, 

fluxing is not typically done in the 

hearth, and hearth emissions (which 

include products of combustion from 

the oil and gas-fired furnaces) are 

typically uncontrolled. 

Process furnaces may process 

contaminated scrap which can result in 

HAP emissions. In addition, fluxing 

agents may contain compounds capable 

of producing HAP, some fraction of 

which is emitted from the furnace. 

Process furnaces are significant sources 

of HAP emissions in the secondary 

aluminum industry. An uncontrolled 

melting furnace which processes 

contaminated scrap and uses reactive 

fluxes emits PM (of which some fraction 

is particulate metal HAP), HCl and D/F. 

Process furnaces are divided into 

group 1 and group 2 furnaces. Group 1 

furnaces are unrestricted in the type of 

scrap they process and the type of fluxes 

they can use. Group 2 furnaces process 

only clean charge and conduct no 

reactive fluxing. 

Dross-only furnaces are furnaces 

dedicated to reclamation of aluminum 

from drosses formed during the melting/ 

holding/alloying operations carried out 

in other furnaces. Exposure to the 

atmosphere causes the molten 

aluminum to oxidize, and the flotation 

of the impurities to the surface along 

with any salt flux creates ‘‘dross.’’ Prior 

to tapping, the dross is periodically 

skimmed from the surface of the 

aluminum bath and cooled. Dross-only 

furnaces are typically rotary barrel 

furnaces (also known as salt furnaces). 

A dross-only furnace emits PM (of 

which some fraction is particulate metal 

HAP). 

Rotary dross coolers are devices used 

to cool dross in a rotating, water-cooled 

drum. A rotary dross cooler emits PM 

(of which some fraction is particulate 

metal HAP). 

In-line fluxers are devices used for 

aluminum refining, including degassing, 

outside the furnace. The process 

involves the injection of chlorine, argon, 

nitrogen or other gases to achieve the 

desired metal purity. In-line fluxers are 

found primarily at facilities that 

manufacture very high quality 

aluminum or in facilities with no other 

means of degassing. An in-line fluxer 

operating without emission controls 

emits HCl and PM. 

A summary description of 

requirements in the existing subpart 

RRR NESHAP is provided below for the 

convenience of the reader. The 

inclusion of this description, however, 

does not reopen the existing rule 

requirements and we are neither 

reconsidering nor soliciting public 

comment on the requirements 

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72880 Federal Register / Vol. 79, No. 235 / Monday, December 8, 2014 / Proposed Rules 

described. In addition, this summary 

description should not be relied on to 

determine applicability of the regulatory 

provisions or compliance obligations. 

The proposed decisions and rule 

amendments addressed in section IV 

below are the only provisions on which 

we are taking comment. 

The NESHAP for the Secondary 

Aluminum Production source category 

were promulgated on March 23, 2000 

(65 FR 15690) and codified at 40 CFR 

part 63, subpart RRR (referred to from 

here on as subpart RRR in the remainder 

of this document). The rule was 

amended at 67 FR 79808, December 30, 

2002; 69 FR 53980, September 3, 2004; 

70 FR 57513, October 3, 2005 and 70 FR 

75320, December 19, 2005. The existing 

subpart RRR NESHAP regulates HAP 

emissions from secondary aluminum 

production facilities that are major 

sources of HAP that operate aluminum 

scrap shredders, thermal chip dryers, 

scrap dryers/delacquering kilns/

decoating kilns, group 1 furnaces, group 

2 furnaces, sweat furnaces, dross-only 

furnaces, rotary dross coolers and 

secondary aluminum processing units 

(SAPUs). The SAPUs include group 1 

furnaces and in-line fluxers. The 

subpart RRR NESHAP regulates HAP 

emissions from secondary aluminum 

production facilities that are area 

sources of HAP only with respect to 

emissions of D/F from thermal chip 

dryers, scrap dryers/delacquering kilns/ 

decoating kilns, group 1 furnaces, sweat 

furnaces and SAPUs. 

The secondary aluminum industry 

consists of approximately 161 secondary 

aluminum production facilities, of 

which the EPA estimates 53 to be major 

sources of HAP. The HAP emitted by 

these facilities are metals, organic HAP, 

D/F, HCl and hydrogen fluoride (HF). 

Several of the secondary aluminum 

facilities are co-located with primary 

aluminum, coil coating and possibly 

other source category facilities. Natural 

gas boilers or process heaters may also 

be co-located at a few secondary 

aluminum facilities. 

The standards promulgated in 2000 

established emission limits for PM as a 

surrogate for metal HAP, THC as a 

surrogate for organic HAP other than 

D/F, D/F expressed as toxic equivalents 

and HCl as a surrogate for acid gases 

including HF, chlorine and fluorine. 

HAP are emitted from the following 

affected sources: Aluminum scrap 

shredders (subject to PM standards), 

thermal chip dryers (subject to 

standards for THC and D/F), scrap 

dryers/delacquering kilns/decoating 

kilns (subject to standards for PM, D/F, 

HCl and THC), sweat furnaces (subject 

to D/F standards), dross-only furnaces 

(subject to PM standards), rotary dross 

coolers (subject to PM standards), group 

1 furnaces (subject to standards for PM, 

HCl and D/F) and in-line fluxers 

(subject to standards for PM and HCl). 

Group 2 furnaces and certain in-line 

fluxers are subject to work practice 

standards. Table 2 provides a summary 

of the current MACT emissions limits 

for existing and new sources under the 

subpart RRR NESHAP. 

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Table 2. Emission Standards for New and Existing Affected 

Sources for the Secondary Aluminum Source Category2 

Affected source/ Emission unit 

All new and existing affected 

sources and emission units 

that are controlled with a PM 

add-on control device and that 

choose to monitor with a 

Continuous Opacity Monitor 

(COM) and all new and existing 

aluminum scrap shredders that 

choose to monitor with a COM 

or to monitor visible 

emissions 

New and existing aluminum 

scrap shredder 

New and existing thermal chip 

dryer 

New and existing scrap 

dryer/delacquering 

kiln/decoating kiln 

Alternative limits if 

afterburner has a design 

residence time of at least 1 

second and operates at a 

temperature of at least 

1,400°F 

Or 

New and existing sweat furnace 

New and existing dross-only 

furnace 

New and existing in-line 

fluxerc 

New and existing in-line 

fluxer with no reactive 

fluxing 

New and existing rotary dross 

cooler 

Pollutant 

Opacity 

PM 

THC 

D/Fa 

PM 

HCl 

THC 

D/Fa 

PM 

HCl 

THC 

D/Fa 

PM 

HCl 

PM 

PM 

2 40 CFR Part 63, Subpart RRR, Table 1. 

Limit Units 

10 percent 

0.01 gr/dscf 

0.80 lb/ton of feed 

2.50 pg TEQ/Mg of 

feed 

0.08 lb/ton of feed 

0.80 lb/ton of feed 

0.06 lb/ton of feed 

0.25 pg TEQ/Mg of 

feed 

0.30 lb/ton of feed 

1.50 lb/ton of feed 

0.20 lb/ton of feed 

5. 0 pg TEQ/Mg of 

feed 

0.80 ng TEQ/dscm@ 

11% 02b 

0.30 lb/ton of feed 

0.04 lb/ton of feed 

0.01 lb/ton of feed 

No Work practice: 

limit no reactive 

fluxing 

0. 04 gr/dscf 
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New and existing clean furnace 

(Group 2) 

New and existing group 1 

melting/holding furnace 

(processing only clean 

charge) c 

New and existing group 1 

furnacec 

New and existing group 1 

furnacec with clean charge 

only 

New and existing secondary 

aluminum processing unita,d 

(consists of all existing 

group 1 furnaces and existing 

in-line flux boxes at the 

facility, or all 

simultaneously constructed new 

group 1 furnaces and new inline fluxers) 

PM 

HCl 

PM 

HCl 

PM 

HCl 

No 

limit 

Work practices: 

clean charge 

only and no 

reactive fluxing 

No 

0.80 lb/ton of feed 

0.40 lb/ton of feed 

or 

10 percent of the 

HCl upstream of 

an add-on 

control device 

0.40 lb/ton of feed 

0.40 lb/ton of feed 

or 

10 Percent of the 

HCl upstream of 

an add-on 

control device 

15.0 pg TEQ/Mg of 

feed 

0.40 lb/ton of feed 

0.40 lb/ton of feed 

or 

10 percent of the 

HCl upstream of 

an add-on 

control device 

Limit 

Clean charge 

only 

~(L. ~ x T.) lpM l 

L fp;vt 

i=l 

n 

:L,(T;) 

i=l 

n ( L. xT ) L 'HCt l 

L t riC! 

i=I 

n 

:L,(T;) 

i=l 
Federal Register / Vol. 79, No. 235 / Monday, December 8, 2014 / Proposed Rules 72883 

Control devices currently in use to 

reduce emissions from affected sources 

subject to the subpart RRR NESHAP 

include fabric filters for control of PM 

from aluminum scrap shredders; 

afterburners for control of THC and D/ 

F from thermal chip dryers; afterburners 

plus lime-injected fabric filters for 

control of PM, HCl, THC and D/F from 

scrap dryers/delacquering kilns/

decoating kilns; afterburners for control 

of D/F from sweat furnaces; fabric filters 

for control of PM from dross-only 

furnaces and rotary dross coolers; limeinjected fabric filters for control of PM 

and HCl from in-line fluxers; and limeinjected fabric filters for control of PM, 

HCl and D/F from group 1 furnaces. All 

affected sources with add-on controls 

are also subject to design requirements 

and operating limits to limit fugitive 

emissions. 

Compliance with the emission limits 

in the current rule is demonstrated by 

an initial performance test for each 

affected source. Repeat performance 

tests are required every 5 years. Area 

sources are only subject to one-time 

performance tests for D/F. After the 

compliance tests, facilities are required 

to monitor various control parameters or 

conduct other types of monitoring to 

ensure continuous compliance with the 

MACT standards. Owners or operators 

of sweat furnaces that operate an 

afterburner that meets temperature and 

residence time requirements are not 

required to conduct performance tests. 

C. What is the history of the Secondary 

Aluminum Risk and Technology 

Review? 

On February 14, 2012 (77 FR 8576), 

we proposed that no amendments to 

subpart RRR were necessary as a result 

of the residual risk and technology 

review (RTR) conducted for the 

Secondary Aluminum Production 

source category. In the same notice (77 

FR 8576, which is referred to as the 

2012 proposal in the remainder of this 

Federal Register document), we 

proposed amendments to correct and 

clarify existing requirements in subpart 

RRR. In this supplemental proposal, we 

are soliciting comment on modified 

proposed amendments to the subpart 

RRR rule requirements and on 

alternative compliance options related 

to sweat furnaces. The proposed 

revisions and alternative compliance 

options, described in more detail later 

in this document, on which we are 

soliciting comment are: 

• Revised proposed limit on number 

of allowed furnace operating mode 

changes per year (i.e., frequency) in 

proposed section 63.1514(e) of four 

times in any 6-month period, with the 

ability of sources to apply to the 

appropriate authority for additional 

furnace operating mode changes; 

• Revised wording in proposed 

section 63.1511(b)(1) related to testing 

under worst-case scenario clarifying 

under what conditions the performance 

tests are to be conducted; 

• Revised proposed requirements to 

account for fugitive emissions during 

performance testing of uncontrolled 

furnaces, including: (1) Installation of 

hooding according to American 

Conference of Government Industrial 

Hygienists (ACGIH) guidelines; (2) 

application of an assumption of 67 

percent capture/control efficiency when 

calculating emissions; or (3) in certain 

cases where installing ACGIH hooding 

is impractical, allowing the facility to 

petition the permitting authority for 

major sources or the Administrator for 

area sources, for approval to use 

alternative testing procedures that will 

minimize fugitive emissions; 

• Revised proposed requirement that 

emission sources comply with the 

emissions limits at all times including 

periods of startup and shutdown. 

Definitions of startup and shutdown are 


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being proposed as well as an alternative 

method for demonstrating compliance 

with emission limits; 

• Revised proposed monitoring 

requirements in section 63.1510(d)(2) 

that require annual inspection of 

capture/collection systems; 

• Revised proposed compliance dates 

of 180 days for certain requirements and 

2 years for other requirements; and 

• Revised operating and monitoring 

requirements for demonstrating 

compliance for sweat furnaces. 

In addition, we are withdrawing our 

2012 proposal to include provisions 

establishing an affirmative defense in 

light of a recent court decision vacating 

an affirmative defense in one of the 

EPA’s section 112(d) regulations. NRDC 

v. EPA, 749 F.3d 1055 (D.C. Cir. 2014) 

(vacating affirmative defense provisions 

in Section 112(d) rule establishing 

emission standards for Portland cement 

kilns). 

After reviewing the comments, data 

and other information received after the 

2012 proposal, we determined it is 

appropriate to present certain revised 

analyses and revised proposed 

amendments in this supplemental 

proposal to allow the public an 

opportunity to review and comment on 

these revised analyses and revised 

proposed amendments. 

The 2012 proposal also contained 

other proposed requirements (topics 

listed below) for which we have not 

made any changes to the analyses, and, 

therefore, on which we are not seeking 

public comment in this document. 

Other amendments or requirements that 

we proposed in 2012, which we are not 

re-opening for comment, are the 

following: 

• Electronic reporting. 

• ACGIH Guidelines. 

• Lime injection rate. 

• Flux monitoring. 

• Cover flux. 

• Bale breakers. 

• Bag Leak Detection Systems (BLDS). 

• Sidewell furnaces. 

• Testing representative units. 

• Initial performance tests. 

• Scrap dryer/delacquering/decoating 

kiln definition. 

• Group 2 furnace definition. 

• HF emissions compliance. 

• SAPU definition. 

• Clean charge definition. 

• Residence time definition. 

• SAPU feed/charge rate. 

• Dross-only versus dross/scrap 

furnaces. 

• Applicability of rule to area 

sources. 

• Altering parameters during testing 

with new scrap streams. 

• Controlled furnaces that are 

temporarily idled for 24 hours or longer. 

• Annual compliance certification for 

area sources. 

The comment period for the February 

2012 proposal ended on April 13, 2012. 

We will address the comments we 

received during the public comment 

period for the 2012 proposal, as well as 

comments received during the comment 

period for this supplemental proposal, 

at the time we take final action. 

Subpart RRR inadvertently uses 

several different terms for the agency 

that has primary responsibility for 

implementation of certain subpart RRR 

provisions. The terms used include 

‘‘responsible permitting authority,’’ 

‘‘permitting authority,’’ ‘‘applicable 

permitting authority’’ and ‘‘delegated 

authority.’’ Depending on the particular 

state and whether the facility is a major 

or area source, the permitting authority 

and the delegated authority for purposes 

of subpart RRR may be the same or may 

differ. Therefore, the EPA deems it 

appropriate to clarify for purposes of 

these specific subpart RRR provisions 

that the ‘‘permitting authority’’ (defined 

in the General Provisions as the Title V 

permitting authority) is the primary 

implementing authority for major 

sources, and the Administrator is the 

primary implementing authority for area 

sources. The General Provisions define 

‘‘Administrator’’ to mean the EPA 

Administrator or his or her authorized 

representative (e.g., a state that has been 

delegated authority to implement 

Subpart RRR). 

Where these terms for the 

implementing authority appear in this 

supplemental proposal, we have made 

the necessary corrections. We plan to 

correct the remainder of these references 

when we issue the final rule. 

D. What data collection activities were 

conducted to support this action? 

For the risk analysis performed for the 

2012 proposal, we compiled a dataset 

from two primary sources: (1) A ninecompany testing information collection 

request (ICR) sent in May 2010, and (2) 

an all-company ICR sent to companies 

in February 2011. These data collection 

efforts are described in the 2012 

proposal, and a comprehensive 

description of the emissions data, 

calculations and risk assessment inputs 

are in the memorandum, Development 

of the RTR Risk Modeling Dataset for 

the Secondary Aluminum Production 

Source Category (Docket item EPA–HQ– 

OAR–2010–0544–0149). 

For the revised risk analysis 

conducted for this supplemental 

proposal, changes were made in the 

methodology used to calculate 

allowable emissions. Generally, 

allowable emissions were calculated for 

the 2012 proposal as the product of the 

emissions limit for the secondary 

aluminum emissions unit and the 

maximum production capacity of the 

unit. For the revised emissions 

modeling for this supplemental 

proposal, the amount of charge to the 

unit from the all-company ICR was used 

in the allowable emissions calculation, 

rather than the maximum production 

capacity of the unit. Uniformly 

assuming that every piece of equipment 

is being used at maximum capacity 

results in an overestimate of total 

aluminum throughput that is much 

larger than the actual throughput for the 

facility as a whole. Moreover, if we 

assume maximum production capacity 

coupled with the assumption that all 

HAP are being emitted at the highest 

level allowed by the MACT rule (i.e., at 

the level of the emissions limit), this 

results in an overly conservative 

estimate of emissions. This 

overestimation is magnified for large 

facilities, with multiple pieces of 

equipment. Therefore, for this 

supplemental proposal, the amount of 

charge to the unit from the all-company 

ICR was used in the allowable emissions 

calculation, rather than the maximum 

production capacity of the unit. 

Furthermore, this revised methodology 

is consistent with EPA’s risk assessment 

methodology performed in other RTR 

modeling projects. See National 

Emission Standards for Hazardous Air 

Pollutants: Primary Lead Smelting; 

proposed rule (76 FR 9410, February 17, 

2011), National Emissions Standards for 

Hazardous Air Pollutants: Secondary 

Lead Smelting; proposed rule (76 FR 

29032, May 19, 2011) and National 

Emissions Standards for Hazardous Air 

Pollutants: Ferroalloys Production (76 

FR 72508, November 23, 2011). For an 

in-depth description of the revised risk 

modeling dataset, including changes in 

methodologies between the emissions 

modeling for the 2012 proposal and the 

emissions modeling for this 

supplemental proposal, see the 

memorandum, Development of the RTR 

Supplemental Proposal Risk Modeling 

Dataset for the Secondary Aluminum 

Production Source Category, available 

in this rulemaking docket. 

As part of the revised risk analysis, 

process equipment and unit emissions 

data used in the emissions modeling for 

the 2012 proposal were also reviewed. 

Since cancer risks were driven by D/F 

emissions in the modeling done for the 

2012 proposal, we focused our refined 

assessment on the D/F emissions data. 

The other modeled pollutants had 

considerably lower estimated risks 

(compared to D/F) and the estimated 

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3U.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. 

risks for all these HAP were well below 

the presumptive acceptable risk levels. 

For almost all facilities, the D/F 

emissions reported in the 2011 ICR 

responses were used for the revised 

modeling. However, for the companies 

operating the 10 facilities that had the 

highest modeled risk from actual 

emissions in the modeling for the 2012 

proposal, we requested and received 

results from additional compliance D/F 

testing that was conducted since the 

2011 ICR. The results for all test runs 

associated with 2011 ICR responses and 

all test runs received as part of the 

request for additional test data were 

averaged together for each facility to 

provide more accurate estimates of the 

D/F emissions and resulting risks for 

these facilities. A memorandum 

comparing the 2011 emissions data with 

the revised emissions data used for this 

supplemental proposal and the reasons 

for differences is available in the docket 

for this rulemaking. See Modeling Input 

Revisions for the RTR Risk Modeling 

Dataset for the Secondary Aluminum 

Production Source Category. 

We also revised emissions data for 

primary aluminum operations at 

primary aluminum facilities that were 

co-located at secondary aluminum 

facilities. The revised primary 

aluminum emissions data were based on 

recent test data used in the 

supplemental proposed rulemaking for 

the Primary Aluminum Production 

source category. These data included 

the following: 

• Additional emission test data for 

polycyclic organic matter (POM) 

emissions from prebake potlines; 

• Additional emission test data for 

PM emissions from prebake and 

Soderberg potlines, anode bake furnaces 

and paste plants; 

• Additional emission test data for 

speciated polycyclic aromatic 

hydrocarbons (PAHs), speciated HAP 

metals, speciated polychlorinated 

biphenyls (PCBs) and speciated D/Fs 

from potlines, anode bake furnaces and 

paste plants. 

III. Analytical Procedures 

A. How did we evaluate the post-MACT 

risks posed by the Secondary Aluminum 

Production source category in the risk 

assessment developed for this 

supplemental proposal? 

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 

noncancer health effects and the hazard 

quotient (HQ) for acute exposures to 

HAP with the potential to cause 

noncancer 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 which provides more 

information on the risk assessment 

inputs and models used for this revised 

assessment: Residual Risk Assessment 

for the Secondary Aluminum 

Production Source Category in Support 

of the 2014 Supplemental Proposal. The 

methods used to assess risks (as 

described in the seven primary steps 

below) are consistent with those peerreviewed by a panel of the EPA’s 

Science Advisory Board (SAB) in 2009 

and described in their peer review 

report issued in 2010; 3 they are also 

consistent with the key 

recommendations contained in that 

report. 

1. How did we estimate actual 

emissions and identify the emissions 

release characteristics? 

As explained in section II.D above, 

the revised RTR emissions dataset for 

the Secondary Aluminum Production 

source category constitutes the basis for 

the revised risk assessment. This 

includes recent test data received from 

the primary aluminum facilities that 

were co-located at secondary aluminum 

production facilities. We estimated the 

magnitude of emissions using emissions 

test data collected through ICRs along 

with more recent data submitted by 

companies with facilities identified as 

the highest risk facilities for D/F 

emissions in the 2012 risk analysis. We 

also reviewed the information regarding 

emissions release characteristics such as 

stack heights, stack gas exit velocities, 

stack temperatures and source locations. 

In addition to the data quality checks 

performed on the source data for the 

facilities contained in the dataset, we 

also verified the coordinates of every 

emission source in the dataset through 

visual observations using Google Earth. 

We also performed data quality checks 

on the emissions data and release 

characteristics. The revised emissions 

data, the data quality checks and the 

methods used to estimate emissions 

from all the various emissions sources, 

are described in more detail in the 

technical documents: Development of 

the RTR Supplemental Proposal Risk 

Modeling Dataset for the Secondary 

Aluminum Production Source Category 

and Modeling Input Revisions for the 

RTR Risk Modeling Dataset for the 

Secondary Aluminum Production 

Source Category, which are available in 

the docket for this action. 

2. How did we estimate MACTallowable emissions? 

The available emissions data in the 

RTR emissions dataset include estimates 

of the 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 MACTallowable 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). 

For this supplemental proposal, we 

evaluated allowable stack emissions 

based on the level of control required by 

the subpart RRR MACT standards. As 

described in section II.D above, changes 

were made in the methodology used to 

calculate the allowable emissions for the 

revised risk analysis conducted for this 

supplemental proposal. In the 2012 

proposal, allowable emissions were 

calculated using the emissions limits for 

the 67 secondary aluminum emissions 

units and the maximum production 

capacity of each unit. For the revised 

emissions modeling, the actual amount 

of charge to the unit from the allcompany ICR was used in the allowable 

emissions calculation, rather than the 

maximum production capacity of the 

unit. The methodology used to calculate 

allowable emissions is explained in 

more detail in the technical documents: 

Development of the RTR Supplemental 

Proposal Risk Modeling Dataset for the 

Secondary Aluminum Production 

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4This metric comes from the Benzene NESHAP. 

See 54 FR 38046. 

5U.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). 

6A census block is the smallest geographic area 

for which census statistics are tabulated. 

7These 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 the EPA’s National Air Toxics Assessment 

(NATA) titled, NATA—Evaluating the Nationalscale Air Toxics Assessment 1996 Data—an SAB 

Advisory, available at: http://yosemite.epa.gov/sab/ 

sabproduct.nsf/

214C6E915BB04E14852570CA007A682C/$File/

ecadv02001.pdf. 

Source Category and Modeling Input 

Revisions for the RTR Risk Modeling 

Dataset for the Secondary Aluminum 

Production Source Category, which are 

available in the docket for this action. 

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 4, and (3) estimating individual 

and population-level inhalation risks 

using the exposure estimates and 

quantitative dose-response information. 

The air dispersion model used by the 

HEM–3 model (AERMOD) is one of the 

EPA’s preferred models for assessing 

pollutant concentrations from industrial 

facilities.5 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 6 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 

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 http://www.epa.gov/ttn/ 

atw/toxsource/summary.html and are 

discussed in more detail later in this 

section. 

In developing the risk assessment for 

chronic exposures, we used the 

estimated annual average ambient air 

concentrations of each HAP emitted by 

each major source and D/F emissions 

from each area 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 (mg/m3)) 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 EPA 

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 doseresponse 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 7) 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. 

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) 

(http://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 (http://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) (http:// 

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 (mg/m3) for inhalation 

exposure and in a dose expressed in 

units of milligram per kilogram-day 

(mg/kg-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 

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8National Academy of Sciences (NAS), 2001. 

Standing Operating Procedures for Developing 

Acute Exposure Levels for Hazardous Chemicals, 

page 2. 

9ERP Committee Procedures and Responsibilities. 

November 1, 2006. American Industrial Hygiene 

Association. 

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. 

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. In some 

cases, the agency may choose to refine 

the acute screen by also assessing the 

exposure that may occur at a centroid of 

a census block. 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 doseresponse values. These acute doseresponse 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. 

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 (http://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. 

As we state above, in assessing the 

potential risks associated with acute 

exposures to HAP, we do not follow a 

prioritization scheme and, therefore, we 

consider available dose-response values 

from multiple authoritative sources. In 

the RTR program, the EPA assesses 

acute risk using toxicity values derived 

from one hour exposures. 

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 (http://www.epa.gov/oppt/

aegl/pubs/sop.pdf),8 ‘‘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. 

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/m3 (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 (ERP) Committee document 

titled, ERPGS Procedures and 

Responsibilities (https://www.aiha.org/

get-involved/AIHAGuideline

Foundation/EmergencyResponse

PlanningGuidelines/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.’’ 9 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. 

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 

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10See http://www.tceq.state.tx.us/compliance/

field_ops/eer/index.html or docket to access the 

source of these data. 

11The SAB peer review of RTR Risk Assessment 

Methodologies is available at: http://

yosemite.epa.gov/sab/sabproduct.nsf/

4AB3966E263D943A8525771F00668381/$File/EPASAB-10-007-unsigned.pdf. 

12U.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 http://

cfpub.epa.gov/ncea/cfm/

recordisplay.cfm?deid=211003. 

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 9.10

Considering this analysis, to account for 

more than 99 percent of the peak hourly 

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. For this 

source category, there was no such 

information available and the default 

factor of 10 was used in the acute 

screening process. 

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. 

As part of our acute risk assessment 

process, for cases where acute HQ 

values from the screening step are less 

than or equal to 1 (even under the 

conservative assumptions of the 

screening analysis), acute impacts are 

deemed negligible and no further 

analysis is performed. In cases where an 

acute HQ from the screening step are 

greater than 1, additional site-specific 

data would be considered to develop a 

more refined estimate of the potential 

for acute impacts of concern. However, 

for this source category, no acute values 

were greater than 1. Therefore, further 

refinement was not performed. 

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,11 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 12 for HAP have 

been developed, we consider additional 

acute values (i.e., occupational and 

international values) to provide a more 

complete risk characterization. 

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 major sources 

in the 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: 

http://www2.epa.gov/fera/riskassessment-and-modeling-air-toxicsrisk-assessment-reference-library). Since 

D/F is the only pollutant for which 

subpart RRR area sources are regulated 

under CAA section 112(d), this was the 

only PB–HAP evaluated in this 

screening analysis for area sources. 

For major sources in the Secondary 

Aluminum Production source category, 

we identified emissions of cadmium 

compounds, D/F, lead compounds, 

mercury compounds and POM. Because 

one or more of these PB–HAP are 

emitted by at least one facility in the 

Secondary Aluminum Production 

source category, we proceeded to the 

next step of the evaluation. In this step, 

we determined whether the facilityspecific 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, D/F, 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 facilityspecific 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 TRIMscreen or Tier 1 screen. 

For the purpose of developing 

emissions rates for our Tier 1 TRIMscreen, 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 D/F 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 

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13 In doing so, the 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. 

14The secondary lead NAAQS 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.’’ 

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 scenarios for the subsistence 

fisher and the subsistence farmer change 

with meteorology and environmental 

assumptions. PB–HAP emissions that do 

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 

screening analysis. 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. 

For this source category, we 

conducted a Tier 3 screening analysis 

for six major sources with Tier 2 cancer 

screen values greater than or equal to 50 

times the Tier 2 threshold for the 

subsistence fisher scenario. The major 

sources represented the highest 

screened cancer risk for multipathway 

impacts. Therefore, further screening 

analyses were not performed on the area 

sources. A detailed discussion of the 

approach for this risk assessment can be 

found in Appendix 8 of the Residual 

Risk Assessment for the Secondary 

Aluminum Production Source Category 

in Support of the 2014 Supplemental 

Proposal. 

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.13

Values below the level of the primary 

(health-based) lead NAAQS were 

considered to have a low potential for 

multipathway risk. 

For further information on the 

multipathway analysis approach, see 

the Residual Risk Assessment for the 

Secondary Aluminum Production 

Source Category in Support of the 2014 

Supplemental Proposal, 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, D/F, POM, 

mercury (both inorganic mercury and 

methyl mercury) and lead compounds. 

The two acid gases are HCl and HF. The 

rationale for including these seven HAP 

in the environmental risk screening 

analysis is presented below. 

The 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 increase 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 National 

Emissions Inventory (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, D/F, 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.14 We 

consider values below the level of the 

secondary lead NAAQS as unlikely to 

cause adverse environmental effects. 

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 peerreviewed ecological effects benchmarks 

that are of sufficient quality for making 

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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 

PB–HAP in sediment in nearby water 

bodies; and 

• 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 

following population-level ecological 

assessment endpoint to screen for 

indirect HAP exposures of top 

consumers via the bioaccumulation of 

HAP in food chains; 

• Piscivorous (i.e., fish-eating) 

wildlife consuming PB–HAPcontaminated fish from nearby water 

bodies. 

For cadmium compounds, D/F, 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 mg of HAP per liter of 

water) that has been linked to a 

particular environmental effect level 

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; 

and 

• 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 

in the analysis, 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 

following ecological assessment 

endpoint: 

• 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 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 of the major source 

facilities in the Secondary Aluminum 

Production source category emitted any 

of the seven environmental HAP. We 

identified emissions of five of the PB– 

HAP (cadmium, mercury, lead, D/F, 

PAHs) and two acid gases (HCl and HF). 

Because one or more of the seven 

environmental HAP evaluated were 

emitted by facilities in the source 

category, we proceeded to the second 

step of the evaluation. Since D/F is the 

only pollutant for which subpart RRR 

area sources are regulated under CAA 

section 112(d), this was the only PB– 

HAP evaluated in this screening 

analysis. 

f. PB–HAP Methodology 

For cadmium, mercury, POM and D/ 

F, 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 for the 

major sources were large enough to 

create the potential for adverse 

environmental effects under reasonable 

worst-case environmental conditions. 

This same assessment was done for area 

sources for D/F because this is the only 

pollutant for which subpart RRR area 

sources are regulated under CAA 

section 112(d). 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 

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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 5 

modeled soil concentrations at various 

distances from the facility (5 soil 

concentrations × 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 is 

typically not evaluated further. If 

emissions from a facility exceed the Tier 

2 screening level, the facility does not 

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 singletier 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 

Secondary Aluminum Production 

Source Category in Support of the 2014 

Supplemental Proposal, 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 of interest, but 

also emissions of HAP from all other 

emissions sources at the facility for 

which we have data. For the Secondary 

Aluminum Production source category, 

we had nine facilities that were colocated with primary aluminum 

reduction plants. 

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 

Development of the RTR Supplemental 

Proposal Risk Modeling Dataset for the 

Secondary Aluminum Production 

Source Category and Modeling Input 

Revisions for the RTR Risk Modeling 

Dataset for the Secondary Aluminum 

Production Source Category, which are 

available in the docket for this action. 

The other uncertainties are described in 

more detail in the Residual Risk 

Assessment for the Secondary 

Aluminum Production Source Category 

in Support of the 2014 Supplemental 

Proposal, 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, errors in emission 

estimates and other factors. The 

emission estimates considered in this 

analysis generally 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 of 10 

applied to the average annual hourly 

emission rates for all emission process 

groups, which are intended to account 

for emission fluctuations due to normal 

facility operations. A description of the 

development of the emissions dataset is 

in section II.D of this preamble and in 

the documents, Development of the RTR 

Supplemental Proposal Risk Modeling 

Dataset for the Secondary Aluminum 

Production Source Category and 

Modeling Input Revisions for the RTR 

Risk Modeling Dataset for the Secondary 

Aluminum Production Source Category, 

which are in the docket for this 

rulemaking. 

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 

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15Short-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. 

16U.S. EPA. National-Scale Air Toxics 

Assessment for 1996. (EPA 453/R–01–003; January 

2001; page 85.) 

17 IRIS glossary (http://www.epa.gov/NCEA/iris/

help_gloss.htm). 

18An 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. 

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 

domain were not considered.15 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). 

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 underpredict 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.16

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 doseresponse relationships is given in the 

Residual Risk Assessment for the 

Secondary Aluminum Production 

Source Category in Support of the 2014 

Supplemental Proposal, 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).17 In some 

circumstances, the true risk could be as 

low as zero; however, in other 

circumstances the risk could be 

greater.18 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 

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19According 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 the 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: 

http://www.epa.gov/osa/pdfs/ratf-final.pdf. 

20 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. 

other uses (e.g., priority-setting or 

expected benefits analysis). 

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 

(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) 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,19 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. 

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 effectspecific 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 shortterm dose-response values at different 

levels of severity should be factored into 

the risk characterization as potential 

uncertainties. 

Although every effort is made to 

identify appropriate human health effect 

dose-response assessment values for all 

pollutants emitted by the sources in this 

risk assessment, some HAP emitted by 

this source category are lacking doseresponse assessments. Accordingly, 

these pollutants cannot be included in 

the quantitative risk assessment, which 

could result in quantitative estimates 

understating HAP risk. To help to 

alleviate this potential underestimate, 

where we conclude similarity with a 

HAP for which a dose-response 

assessment value is available, we use 

that value as a surrogate for the 

assessment of the HAP for which no 

value is available. To the extent use of 

surrogates indicates appreciable risk, we 

may identify a need to increase priority 

for new IRIS assessment of that 

substance. We additionally note that, 

generally speaking, HAP of greatest 

concern due to environmental 

exposures and hazard are those for 

which dose-response assessments have 

been performed, reducing the likelihood 

of understating risk. 

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 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.20

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 SAB reviews 

and other reviews, we are confident that 

the models used in the screen are 

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21 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. 

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 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. The multipathway 

screens include some hypothetical 

elements, namely the hypothetical 

farmer and fisher scenarios. It is 

important to note that even though the 

multipathway assessment has been 

conducted, no data exist to verify the 

existence of either the farmer or fisher 

scenario outlined above. 

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 

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 all the Tiers. 

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 screening 

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 multipathway 

screening methods, refer to the 

Appendix 5 of the Residual Risk 

Assessment for the Secondary 

Aluminum Production Source Category 

in Support of the 2014 Supplemental 

Proposal. 

We completed a Tier 3 refined 

multipathway screening analysis for this 

supplemental proposal for assessing 

multipathway risks. This assessment 

contains less uncertainty compared to 

the Tier 1 and Tier 2 screens. The Tier 

3 screen reduces uncertainty through 

improved lake evaluations used in the 

Tier 2 screen and by calculating the 

amount of mass lost to the upper air 

sink through plume rise. Nevertheless, 

some uncertainties also exist with these 

refined assessments. The Tier 3 

multipathway screen and related 

uncertainties are described in detail in 

the Residual Risk Assessment for the 

Secondary Aluminum Production 

Source Category in Support of the 2014 

Supplemental Proposal, which is 

available in the docket for this action. 

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.21

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 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 

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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 

used at a programmatic level (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.6 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 

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, D/F, 

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 screening methods 

is provided in Appendix 5 of the 

Residual Risk Assessment for the 

Secondary Aluminum Production 

Source Category in Support of the 2014 

Supplemental Proposal, available in the 

docket for this action. 

B. How did we consider the risk results 

in making decisions for this 

supplemental 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) 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. 

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 

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22The EPA’s responses to this and all other key 

recommendations of the SAB’s advisory on RTR 

risk assessment methodologies (which is available 

at: http://yosemite.epa.gov/sab/sabproduct.nsf/

4AB3966E263D943A8525771F00668381/$File/EPASAB-10-007-unsigned.pdf) are outlined in a memo 

to this rulemaking docket from David Guinnup 

titled, EPA’s Actions in Response to the Key 

Recommendations of the SAB Review of RTR Risk 

Assessment Methodologies. 

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 one 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 

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.’’ 22

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 noncancer hazard indices from all noncarcinogens 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 emission 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 

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23Burger, J. 2002. Daily Consumption of Wild 

Fish and Game: Exposures of High End 

Recreationists. International Journal of 

Environmental Health Research 12:343–354. 

24U.S. EPA. Exposure Factors Handbook 2011 

Edition (Final). U.S. Environmental Protection 

Agency, Washington, DC, EPA/600/R–09/052F, 

2011. 

sources in the Secondary Aluminum 

Production 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. Revised Analytical Results and 

Proposed Decisions for the Secondary 

Aluminum Production Source Category 

A. What are the results of the risk 

assessment and analysis? 

1. Inhalation Risk Assessment Results 

Table 3 provides an overall summary 

of the results of the inhalation risk 

assessment. 

TABLE 3—SECONDARY ALUMINUM PRODUCTION SOURCE CATEGORY INHALATION RISK ASSESSMENT RESULTS

Number of facilities modeled 

Maximum individual cancer 

risk (in 1-million) a Estimated 

annual 

cancer 

incidence 

(cases/yr) d

Estimated 

population 

at increased 

risk of 

cancer 

≥1-in-1 

million d

Maximum chronic non-cancer 

TOSHI b

Worst-case maximum 

screening acute 

non-cancer 

HQ c

Based on 

actual 

emissions 

Based on 

allowable 

emissions 

Based on 

actual 

emissions 

level 

Based on 

allowable 

emissions 

level 

Major Sources (52) ....................................... 0 .6 4 0 .0007 0 0 .04 0 .1 HQ(REL) = 0.7 (HF). 

HQ(AEGL1) = 0.4 (HCl). 

Area Sources (103) ....................................... 0 .3 1 0 .001 0 0 .0003 0 .001 NA. 

Facility-wide (52 Major Sources) .................. 70 NA 0 .05 760,000 1 NA NA. 

a Estimated maximum individual excess lifetime cancer risk due to HAP emissions from the source category for major sources and for D/F emissions from the area 

sources. b Maximum TOSHI. The target organ with the highest TOSHI for the Secondary Aluminum Production source category for both actual and allowable emissions is 

the respiratory system. c There is no acute dose-response value for D/F. Thus an acute HQ value for area sources was not calculated. The maximum off-site HQ acute value of 0.7 for 

actuals is driven by emissions of hydrofluoric acid. See section III.A.3 of this document for explanation of acute dose-response values. Acute assessments are not 

performed on allowable emissions. d These estimates are based upon actual emissions. 

The inhalation risk modeling 

performed to estimate risks based on 

actual and allowable emissions relied 

primarily on emissions data from the 

ICRs. The results of the chronic baseline 

inhalation cancer risk assessment 

indicate that, based on estimates of 

current actual emissions, the MIR posed 

by the Secondary Aluminum Production 

source category from major sources and 

from area sources was less than 1-in-1 

million. The estimated cancer incidence 

is slightly higher for area sources 

compared to the major sources due to 

the larger number of area sources 

nationwide. The total estimated cancer 

incidence from secondary aluminum 

production sources from both major and 

area sources based on actual emission 

levels is 0.002 excess cancer cases per 

year, with emissions of D/F, 

naphthalene and PAH contributing 48 

percent, 31 percent and 11 percent, 

respectively, to this cancer incidence. In 

addition, we note that there are no 

excess cancer risks greater than or equal 

to 1-in-1 million as a result of actual 

emissions from this source category over 

a lifetime. The maximum modeled 

chronic non-cancer HI (TOSHI) value 

for the source category for both major 

and area sources based on actual 

emissions was estimated to be 0.04, 

with HCl emissions from group 1 

furnaces accounting for 99 percent of 

the HI. 

When considering MACT-allowable 

emissions, the MIR is estimated to be up 

to 4-in-1 million, driven by emissions of 

D/F compounds, naphthalene and PAHs 

from the scrap dryer/delacquering/

decoating kiln. The estimated potential 

cancer incidence considering allowable 

emissions for both major and area 

sources is estimated to be 0.014 excess 

cancer cases per year, or 1 case every 70 

years. Approximately 3,400 people were 

estimated to have cancer risks greater 

than or equal to 1-in-1 million 

considering allowable emissions from 

secondary aluminum plants. When 

considering MACT-allowable emissions, 

the maximum chronic non-cancer 

TOSHI value was estimated to be 0.1, 

driven by allowable emissions of HCl 

from the group 1 furnaces. 

2. Acute Risk Results 

Our screening analysis for worst-case 

acute impacts based on actual emissions 

indicates no pollutants exceeding an HQ 

value of 1 based upon the REL. 

3. Multipathway Risk Screening Results 

Results of the worst-case Tier 1 

screening analysis indicate that 36 of 

the 52 major sources exceeded the PB– 

HAP emission cancer screening rates 

(based on estimates of actual emissions) 

for D/F, and 3 of the 52 major sources 

exceeded the Tier 1 screen value for 

PAHs. Regarding area sources, 60 of the 

103 area sources exceeded the PB–HAP 

emission cancer screening rates (based 

on estimates of actual emissions) for D/ 

F. For the compounds and facilities that 

did not screen out at Tier 1, we 

conducted a Tier 2 screen. The Tier 2 

screen replaces some of the assumptions 

used in Tier 1 with site-specific data, 

including the location of fishable lakes 

and local precipitation, wind direction 

and speed. The Tier 2 screen continues 

to rely on high-end assumptions about 

consumption of local fish and locally 

grown or raised foods (adult female 

angler at 99th percentile consumption 

for fish 23 for the subsistence fisherman 

scenario and 90th percentile 

consumption for locally grown or raised 

foods 24 for the farmer scenario). It is 

important to note that, even with the 

inclusion of some site-specific 

information in the Tier 2 analysis, the 

multipathway screening analysis is still 

a very conservative, health-protective 

assessment (e.g., upper-bound 

consumption of local fish and locally 

grown and/or raised foods) and in all 

likelihood will yield results that serve 

as an upper-bound multipathway risk 

associated with a facility. 

While the screening analysis is not 

designed to produce a quantitative risk 

result, the factor by which the emissions 

exceed the threshold serves as a rough 

gauge of the ‘‘upper-limit’’ risks we 

would expect from a facility. Thus, for 

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example, if a facility emitted a PB–HAP 

carcinogen at a level 2 times the 

screening threshold, we can say with a 

high degree of confidence that the actual 

maximum cancer risks will be less than 

2-in-1 million. Likewise, if a facility 

emitted a noncancer PB–HAP at a level 

2 times the screening threshold, the 

maximum noncancer hazard would 

represent an HQ less than 2. The high 

degree of confidence comes from the 

fact that the screens are developed using 

the very conservative (health-protective) 

assumptions that we describe above. 

Based on the Tier 2 cancer screening 

analysis, 25 of the 52 major sources and 

34 of the 103 area sources emit D/F 

above the Tier 2 cancer screening 

thresholds for the subsistence fisher and 

farmer scenarios. The individual D/F 

emissions are all scaled based on their 

toxicity to 2,3,7,8-tetrachlorodibenzo-pdioxin and reported as toxic equivalents 

(TEQs). The subsistence fisher scenario 

for the highest risk facilities exceeds the 

D/F cancer threshold by a factor of 80 

for the major sources and by a factor of 

70 for the area sources. The Tier 2 

analysis also identifies 23 of the 52 

major sources and 26 of the 103 area 

sources emitting D/F above the Tier 2 

cancer screening thresholds for the 

subsistence farmer scenario. The highest 

exceedance of the Tier 2 screen value is 

40 for the major sources and 20 for the 

area sources for the farmer scenario. 

We have only one major source 

emitting PAHs above the Tier 2 cancer 

screen value with an exceedance of 2 for 

the farmer scenario. All PAH emissions 

are scaled based on their toxicity to 

benzo(a)pyrene and reported as TEQs. 

A more refined Tier 3 multipathway 

screening analysis was conducted for 

six Tier 2 major source facilities. The six 

facilities were selected because the Tier 

2 cancer screening assessments for these 

facilities had exceedances greater than 

or equal to 50 times the screen value for 

the subsistence fisher scenario. The 

major sources represented the highest 

screened cancer risk for multipathway 

impacts. Therefore, further screening 

analyses were not performed on the area 

sources. The Tier 3 screen examined the 

set of lakes from which the fisher might 

ingest fish. Any lakes that appeared to 

not be fishable or not publicly 

accessible were removed from the 

assessment, and the screening 

assessment was repeated. After we made 

the determination the critical lakes were 

fishable, we analyzed plume rise data 

for each of the sites. The Tier 3 screen 

was conducted only on those HAP that 

exceeded the Tier 2 screening threshold, 

which for this assessment were D/F and 

PAHs. Both of these PB–HAP are 

carcinogenic. The Tier 3 screen resulted 

in lowering the maximum exceedance of 

the screen value for the highest site from 

80 to 70. Results for the other sites were 

all less than 70. The highest exceedance 

of the Tier 2 cancer screen value of 40 

for the farmer scenario was also reduced 

in the Tier 3 screening assessment to a 

value of 30 for the major sources within 

this source category. 

Overall, the refined multipathway 

screening analysis for D/F and PAHs 

utilizing the Tier 3 screen predicts a 

potential lifetime cancer risk of 70-in-1 

million or lower to the most exposed 

individual, with D/F emissions from 

group 1 furnaces handling other than 

clean charge driving the risk. Cancer 

risks due to PAH emissions for the 

maximum exposed individual were less 

than 1-in-1 million. 

The chronic non-cancer HQ is 

predicted to be below 1 for cadmium 

compounds and 1 for mercury 

compounds. For lead, we did not 

estimate any exceedances of the primary 

lead NAAQS. 

Further details on the refined 

multipathway screening analysis can be 

found in Appendix 8 of the Residual 

Risk Assessment for the Secondary 

Aluminum Production Source Category 

in Support of the 2014 Supplemental 

Proposal, which is available in the 

docket. 

4. Environmental Risk Screening Results 

As described in section III.A of this 

document, we conducted an 

environmental risk screening 

assessment for the Secondary 

Aluminum Production source category 

for the following seven pollutants: 

PAHs, mercury (methyl mercury and 

mercuric chloride), cadmium, lead, D/F, 

HCl and HF. 

Of the seven pollutants included in 

the environmental risk screen, major 

sources in this source category emit 

PAHs, mercuric chloride, cadmium, 

lead, D/F, HCl and HF. In the Tier 1 

screening analysis for PB–HAP, none of 

the individual modeled concentrations 

for any facility in the source category 

exceeded any of the ecological 

benchmarks (either the LOAEL or 

NOAEL) for PAHs, mercuric chloride, 

cadmium and D/F. For lead, we did not 

estimate any exceedances of the 

secondary lead NAAQS. For HCl and 

HF, 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 

any ecological benchmark. 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. 

Of the seven pollutants included in 

the environmental risk screen, area 

sources in this source category are 

regulated only for D/F. In the Tier 1 

screening analysis for D/F, none of the 

individual modeled concentrations for 

any facility in the source category 

exceeded any of the ecological 

benchmarks (either the LOAEL or 

NOAEL) for D/F. 

5. Facility-Wide Risk Assessment 

Results 

Considering facility-wide emissions at 

the 52 major sources, the MIR is 

estimated to be 70-in-1 million driven 

by arsenic and Ni emissions, and the 

chronic non-cancer TOSHI value is 

calculated to be 1 driven by emissions 

of cadmium compounds. The above 

risks are driven by emissions from the 

potline roof vents at the co-located 

primary aluminum production 

operations. The Secondary Aluminum 

Production source category represents 

less than 1 percent of the inhalation 

risks from the facility-wide assessment 

based upon actual emissions. Emissions 

from primary aluminum sources are 

being addressed in a separate action. 

Details regarding primary aluminum 

sources are available at http://

www.epa.gov/ttn/atw/alum/

alumpg.html. 

6. What demographic groups might 

benefit from this regulation? 

To determine whether or not to 

conduct a demographics analysis, which 

is an assessment of risks to individual 

demographic groups, we look at a 

combination of factors including the 

MIR, non-cancer TOSHI, population 

around the facilities in the source 

category and other relevant factors. For 

the Secondary Aluminum Production 

source category, inhalation risks were 

low with excess cancer risks being less 

than 1-in-1 million and non-cancer 

hazards being less than 1. Therefore, we 

did not conduct an assessment of risks 

to individual demographic groups for 

this rulemaking. However, we did 

conduct a proximity analysis for both 

area and major sources, which identifies 

any overrepresentation of minority, low 

income or indigenous populations near 

facilities in the source category. The 

results of the proximity analyses suggest 

there are a higher percent of minorities, 

people with low income, and people 

without a high school diploma living 

near these facilities (i.e., within 3 miles) 

compared to the national averages for 

these subpopulations. However, as 

explained above, the risks due to HAP 

emissions from this source category are 

low for all populations (e.g., inhalation 

cancer risks are less than 1-in-1 million 

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25 1-in-10 thousand is equivalent to 100-in-1 

million. The EPA currently describes cancer risks 

as ‘‘n-in-1 million.’’ 

for all populations and non-cancer 

hazard indices are less than 1). 

Furthermore, we do not expect this 

supplemental proposal to achieve 

reductions in HAP emissions. Therefore, 

we conclude that this supplemental 

proposal will not have 

disproportionately high and adverse 

human health or environmental effects 

on minority or low-income populations 

because it does not affect the level of 

protection provided to human health or 

the environment. However, this 

supplemental proposal, if finalized, will 

provide additional benefits to these 

demographic groups by improving the 

compliance, monitoring and 

implementation of the NESHAP. 

The detailed results of the proximity 

analyses can be found in the EJ 

Screening Report for Secondary 

Aluminum Area Sources and the EJ 

Screening Report for Secondary 

Aluminum Major Sources, which are 

available in the docket for this 

rulemaking. 

B. What are our proposed decisions 

regarding risk acceptability, ample 

margin of safety and adverse 

environmental effects based on our 

revised analyses? 

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 25.’’ (54 

FR 38045, September 14, 1989). 

In this proposal, the EPA estimated 

risks based on both actual and allowable 

emissions from secondary aluminum 

facilities. As discussed above, in 

determining acceptability, we 

considered risks based on both actual 

and allowable emissions. 

a. Estimated Risks From Actual 

Emissions 

The baseline inhalation cancer risk to 

the individual most exposed to 

emissions from the Secondary 

Aluminum Production source category 

is from major sources with cancer risks 

less than 1-in-1 million based on actual 

emissions. The total estimated 

incidence of cancer for this source 

category from both major and area 

sources due to inhalation exposures is 

0.002 excess cancer cases per year, or 1 

case in 500 years. The agency estimates 

that the maximum chronic non-cancer 

TOSHI from inhalation exposure for this 

source category is from major sources 

with an HI of 0.04 based on actual 

emissions, with HCl emissions from 

group 1 furnaces accounting for a large 

portion (99 percent) of the HI. 

The multipathway screening analysis, 

based upon actual emissions, indicates 

the excess cancer risk from this source 

category is lower than 70-in-1 million 

with D/F emissions representing 99 

percent of these potential risks based on 

the fisher scenario. The multipathway 

MIR cancer risks are the same for both 

the major and area sources within this 

source category for the fisher scenario. 

For the farmer scenario, the excess 

cancer risk is lower than 30-in-1 million 

for the major sources and 20-in-1 

million for the area sources. There were 

no facilities within this source category 

having a multipathway non-cancer 

screen value greater than 1 for cadmium 

or mercury. 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 mg/m3). 

Results of this analysis estimate that the 

NAAQS for lead would not be exceeded 

at any off-site locations. 

As noted above, the multipathway 

screens are conservative and incorporate 

many health-protective assumptions. 

For example, the EPA chooses inputs 

from the upper end of the range of 

possible values for the influential 

parameters used in the Tier 2 screen and 

assumes that the exposed individual for 

each scenario exhibits ingestion 

behavior that would lead to a high total 

exposure. A Tier 2 or 3 exceedance of 

a cancer or non-cancer screen value 

cannot be equated with an actual risk 

value or a HQ or HI. Rather, it 

represents a high-end estimate of what 

the risk or hazard may be. For example, 

a non-cancer screen value of 2 can be 

interpreted to mean that we have high 

confidence that the HI is lower than 2. 

Similarly, a cancer screen value of 30 

for a carcinogen means that we have 

high confidence that the risk is lower 

than 30-in-1-million. Confidence comes 

from the conservative, or healthprotective, assumptions that are used in 

the Tier 2 and Tier 3 screens. The Tier 

3 screen improves the accuracy of the 

Tier 2 screen through validation of 

impacted lakes assessed and accounting 

for mass lost to the upper air sink, 

which reduces the uncertainty in the 

screen. The maximum Tier 3 

exceedance of the cancer screen values 

for the secondary aluminum source 

category are 70 for the sustainable fisher 

scenario and 30 for the farmer scenario, 

both driven by D/F emissions from 

major sources. 

The screening assessment of worstcase acute inhalation impacts from 

baseline actual emissions indicates no 

pollutants exceeding an HQ value of 1 

based on the REL, with an estimated 

worst-case maximum acute HQ of 0.7 

for HF based on the 1-hour REL. 

b. Estimated Risks From Allowable 

Emissions 

The EPA estimates that the inhalation 

cancer risk to the individual most 

exposed to emissions from the 

Secondary Aluminum Production 

source category is up to 4-in-1 million 

based on allowable emissions from 

major sources, with D/F, naphthalene 

and PAH emissions driving the risks. 

The EPA estimates that the incidence of 

cancer due to inhalation for the entire 

source category based on allowable 

emissions could be up to 0.014 excess 

cancer cases per year, or 1 case 

approximately every 70 years. About 

3,400 people face an estimated 

increased cancer risk greater than or 

equal to 1-in-1 million due to inhalation 

exposure to allowable HAP emissions 

from this source category. 

The risk assessment estimates that the 

maximum chronic non-cancer TOSHI 

from inhalation exposure values for the 

source category is up to 0.1 based on 

allowable emissions, driven by HCl 

emissions from major sources. 

c. Acceptability Determination 

In determining whether risks are 

acceptable for this source category, the 

EPA considered all available health 

information and risk estimation 

uncertainty as described above. As 

noted above, the agency estimated risk 

from 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 

up to but no greater than approximately 

4-in-1 million, based on allowable 

emissions which is considerably less 

than 100-in-1 million, the presumptive 

limit of acceptability. The MIR based on 

actual emissions is 0.6-in-1 million, 

well below the presumptive limit as 

well. The maximum chronic non-cancer 

hazard indices for both the actual and 

allowable inhalation non-cancer risks to 

the individual most exposed are less 

than 1. The maximum individual noncancer HI is 0.04 based on actual 

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emissions and 0.1 based on allowable 

emissions. 

The maximum acute non-cancer HQ 

for all pollutants was below 1, with a 

maximum value of 0.7 based on the REL 

for hydrofluoric acid. The excess cancer 

risks from the multipathway screen 

from actual D/F and PAH emissions 

from major and area sources indicate 

that the risk to the individual most 

exposed could be up to, but no greater 

than, 70-in-1 million for the fisher 

scenario and 30-in-1 million for the 

farmer scenario. These results are less 

than 100-in-1 million, which is the 

presumptive limit of acceptability. The 

multipathway Tier 2 screen for noncancer is at 1 for mercury and cadmium. 

The multipathway screens are based 

on model runs that use upper end 

values for influential parameters and we 

assume that the exposed individual 

exhibits ingestion behavior that would 

lead to a high total exposure. The 

multipathway screens also include some 

hypothetical elements, namely the 

existence and location of the 

hypothetical farmer and fisher. 

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 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 

Under the ample margin of safety 

analysis, we evaluated the cost and 

feasibility of available control 

technologies and other measures 

(including the controls, measures and 

costs reviewed under the technology 

review) that could be applied in this 

source category to further reduce the 

risks (or potential risks) due to 

emissions of HAP identified in our risk 

assessment, along with all of the health 

risks and other health information 

considered in the risk acceptability 

determination described above. In this 

analysis, we considered the results of 

the technology review, risk assessment 

and other aspects of our MACT rule 

review to determine whether there are 

any cost-effective controls or other 

measures that would reduce emissions 

further to provide an ample margin of 

safety with respect to the risks 

associated with these emissions. 

Our inhalation risk analysis indicated 

very low potential for risk from the 

facilities in the source category, and, 

therefore, very little inhalation risk 

reductions could be realized regardless 

of the availability of control options. 

Our technology review, which was 

conducted for the 2012 proposal and is 

in large part applicable to this 

supplemental proposal (see section IV.C 

below for more discussion of the 

technology review), did not identify any 

new practices, controls or process 

options that are being used in this 

industry or in other industries that 

would be cost effective for further 

reduction of these emissions and risks. 

Our multipathway screening analysis 

results for the 2012 proposal indicated 

exceedances of the worst-case screening 

levels which did not necessarily 

indicate any risks. However, they did 

suggest a potential for risks. For this 

supplemental proposal, a more refined 

multipathway screening analysis was 

conducted, including a Tier 3 screen for 

the top six major source facilities for 

cancer. The more refined screening 

analysis was conducted only on those 

PB–HAP that exceeded the screening 

threshold, which for this assessment 

were PAHs and D/F. The refined 

multipathway screening analysis 

showed that the earlier screening 

analysis for the 2012 proposal overpredicted the potential cancer risk when 

compared to the refined analysis for 

three of the six facilities assessed, with 

emissions of D/F driving these cancer 

risks. The remaining facilities had the 

same cancer screen value in the refined 

analysis as in the earlier screening 

results when rounded to 1 significant 

figure. The cancer risks due to PAH 

emissions were less than 1-in-1 million 

based on the refined analysis. 

To evaluate the potential to reduce D/ 

F emissions and risks, as part of our 

revised ample margin of safety analysis, 

we used the same analysis that we 

conducted for the 2012 proposal except 

that we incorporated more recent D/F 

emissions data and control cost 

information. As in the analysis 

conducted for the 2012 proposal, we 

evaluated two control options. Option 1 

considered lowering the existing D/F 

emissions limit from 15 to 10 mg TEQ/ 

Mg feed for all group 1 furnaces 

processing other than clean charge. 

Option 2 considered lowering the 

existing D/F limit for group 1 furnaces 

processing other than clean charge after 

applying a subcategorization based on 

facility production capacity. An 

emission reduction to 10 mg TEQ/Mg 

represents a level that could potentially 

be met with an activated carbon 

injection system. With regard to the 

option of lowering the D/F emission 

limit to 10 mg TEQ/Mg feed for group 1 

furnaces handling other than clean 

charge, we estimate that about 12 

furnaces at eight facilities would need to 

reduce their D/F emissions and that the 

total capital costs would be $390,000 

with total annualized costs of $1.4 

million. This option would achieve an 

estimated 0.49 grams TEQ reduction of 

D/F emissions with an overall cost 

effectiveness of about $2.9 million per 

gram D/F TEQ. For the second option, 

facilities with group 1 furnace 

production capacity greater than 

200,000 tpy (melting other than clean 

charge) would be required to meet a 

limit of 10 mg TEQ/Mg limit. For this 

option, we estimate that 4 furnaces at 

two facilities would be required to 

reduce their D/F emissions. We estimate 

that the total capital costs would be 

$130,000 with total annualized costs of 

$460,000. This option would achieve an 

estimated 0.12 grams TEQ reduction of 

D/F emissions with an overall costeffectiveness of about $3.8 million per 

gram D/F TEQ. As we concluded in the 

ample margin of safety analysis for the 

2012 proposal, our analysis indicates 

that these options would result in very 

little emission reductions (0.49 grams 

TEQ of D/F for Option 1 and 0.12 grams 

TEQ of D/F reductions for Option 2) 

and, therefore, would result in little or 

no changes to the potential risk levels. 

After considering the costs and the level 

of reductions that would be achieved, 

we have decided, as we did in the 2012 

proposal, not to propose any of these 

options. For more information on this 

analysis, see the Supplemental Proposal 

Technical Support Document for the 

Secondary Aluminum Production 

Source Category, which is available in 

the public docket for this proposed 

rulemaking. 

In the 2012 proposal, we also 

evaluated possible options based on 

work practices to achieve further 

emission reductions. The current 

subpart RRR NESHAP includes work 

practices to minimize D/F emissions 

which include scrap inspection, 

limitations on materials processed by 

group 2 furnaces, temperature and 

residence time requirements for 

afterburners controlling sweat furnaces, 

labeling requirements, capture/

collection requirements and 

requirements for an operations, 

maintenance and monitoring plan that 

contains details on the proper operation 

and maintenance of processes and 

control equipment. For the 2012 

proposal, we searched for and evaluated 

other possible work practices such as 

good combustion practices, better scrap 

inspection and cleaning, and process 

monitoring. However, none of these 

potential work practices were 

determined to be feasible and effective 

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in further reducing D/F emissions for 

this source category. Thus, we did not 

identify any feasible or applicable work 

practices for this industry beyond those 

that are currently in the MACT rule. 

Therefore, in the 2012 proposal we did 

not propose any additional work 

practices. Since the 2012 proposal, we 

have not identified any changes in the 

sources of emissions, the types of 

pollutants emitted or the work practices 

available to be used in the secondary 

aluminum production industry. 

Therefore, as in the 2012 proposal, we 

are not proposing any revisions to 

subpart RRR based on work practices. 

Further details on work practices and 

control options are provided in the 

Supplemental Proposal Technology 

Review for the Secondary Aluminum 

Production Source Category, which is 

available in the public docket for this 

rulemaking. 

In accordance with the approach 

established in the Benzene NESHAP, we 

weighed all health risk information and 

factors considered in the risk 

acceptability determination, including 

uncertainties, along with the cost and 

feasibility of control technologies and 

other measures that could be applied in 

this source category, in making our 

ample margin of safety determination. 

In summary, our risk analysis indicated 

very low potential for risk, and we 

identified no developments in 

technology that would be cost effective 

in reducing HAP emissions relative to 

reductions already being achieved. We 

also did not identify any cost effective 

approaches to further reduce D/F 

emissions and multipathway risk 

beyond what is already being achieved 

by the current NESHAP. 

Because of the high cost associated 

with the use of activated carbon 

injection systems and because work 

practices are already required to help 

ensure low emissions, and in light of the 

considerations discussed above, we 

propose that the existing MACT 

standards provide an ample margin of 

safety to protect public health. 

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 

Secondary Aluminum Production 

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. 

C. What are the results and proposed 

decisions based on our technology 

review? 

A technology review was conducted 

for the Secondary Aluminum 

Production source category and is 

described in the 2012 proposal at 77 FR 

8596, February 14, 2012. Details of the 

technology review and its findings are 

available in the memorandum, Draft 

Technology Review for the Secondary 

Aluminum Production Source Category 

(Docket item EPA–HQ–OAR–2010– 

0544–0144). The typical controls used 

to minimize emissions at secondary 

aluminum facilities include fabric filters 

for control of PM from aluminum scrap 

shredders; afterburners for control of 

THC and D/F from thermal chip dryers; 

afterburners plus lime-injected fabric 

filters for control of PM, HCl, THC and 

D/F from scrap dryers/delacquering 

kilns/decoating kilns; afterburners for 

control of D/F from sweat furnaces; 

fabric filters for control of PM from 

dross-only furnaces and rotary dross 

coolers; lime-injected fabric filters for 

control of PM and HCl from in-line 

fluxers; and lime-injected fabric filters 

for control of PM, HCl and D/F from 

group 1 furnaces. In our review of 

technology, we determined that there 

have been some developments in 

practices, processes or control 

technologies that have been 

implemented in this source category 

since promulgation of the current 

NESHAP. We stated in the 2012 

proposal that these findings did not 

warrant any changes to subpart RRR. 

Following the 2012 proposal, no public 

comments were received that would 

alter the conclusions of our technology 

review for the Secondary Aluminum 

Production source category. Therefore, 

for this supplemental proposal, we are 

proposing that the technology review 

findings are still valid. The EPA is not 

aware of any changes in technology 

development since the 2012 proposal. 

As part of the technology review for 

the 2012 proposal, we also evaluated 

other technologies that have the 

potential to reduce HAP emissions, in 

particular emissions of D/F. See Draft 

Technical Support Document for the 

Secondary Aluminum Production 

Source Category, Docket item EPA–HQ– 

OAR–2010–0544–0152. We have 

updated that analysis for this 

supplemental proposal. See 

Supplemental Proposal Technical 

Support Document for the Secondary 

Aluminum Production Source Category 

and the Supplemental Proposal 

Technology Review for the Secondary 

Aluminum Production Source Category, 

which are available in the public docket 

for this rulemaking. Under this analysis, 

we evaluated the same approaches that 

were evaluated under the ample margin 

of safety analysis described in section 

IV.B of this document. We evaluated the 

option of lowering the existing D/F limit 

from 15 to 10 mg TEQ/Mg feed for group 

1 furnaces processing other than clean 

charge either at all secondary aluminum 

facilities or only at larger secondary 

aluminum facilities based on facility 

production capacity. The lower D/F 

emissions limits potentially could be 

met by using an activated carbon 

injection system. Using updated 

information on emissions and control 

costs, we estimate that about 12 

furnaces at eight facilities would need to 

reduce their D/F emissions to meet the 

10 mg TEQ/Mg feed for group 1 furnaces 

and that the total capital costs would be 

$390,000 with total annualized costs of 

$1.4 million. This option would achieve 

an estimated 0.49 grams TEQ reduction 

of D/F emissions with an overall cost 

effectiveness of about $2.9 million per 

gram D/F TEQ. For the second option, 

only facilities with group 1 furnace 

production capacity greater than 

200,000 tpy (melting other than clean 

charge) would be required to meet the 

lower 10 mg TEQ/Mg limit. For this 

option, we estimate that four furnaces at 

two facilities would be required to 

reduce their D/F emissions. We estimate 

that the total capital cost would be 

$130,000 with total annualized costs of 

$460,000. This option would achieve an 

estimated 0.12 grams TEQ reduction of 

D/F emissions with an estimated overall 

cost effectiveness of $3.8 million per 

gram D/F TEQ. (The details of this 

analysis are in the Supplemental 

Proposal Technical Support Document 

for the Secondary Aluminum 

Production Source Category, which is 

available in the public docket for this 

rulemaking. After considering the costs 

and the small emission reductions that 

would be achieved, we have decided 

not to propose any of these options. 

D. What other actions are we proposing? 

In the 2012 proposal, we proposed 

amendments to correct and clarify 

existing requirements in subpart RRR. In 

this supplemental proposal, we are 

proposing revisions to certain rule 

corrections and clarifications that were 

in the 2012 proposal as well as 

proposing alternative compliance 

options to the operating and monitoring 

requirements for sweat furnaces. On 

these limited revisions, we are soliciting 

comment. As discussed above, the 2012 

proposal also contained other proposed 

rule corrections and clarifications for 

which we are not proposing any 

changes in this document, and, 

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therefore, for which we are not seeking 

public comment (if EPA nonetheless 

were to receive any such comments, the 

comments would be outside the scope 

of this supplemental proposal and 

would not be considered). 

1. Changing Furnace Classification 

In the 2012 proposal, we proposed to 

address an area of uncertainty under 

subpart RRR by specifying in 40 CFR 

63.1514 rule provisions expressly 

allowing changes in furnace 

classification, subject to procedural and 

testing requirements, operating 

requirements and recordkeeping 

requirements. We proposed a frequency 

limit of no more than one change in 

classification (and associated reversion) 

every six months, with an exception for 

planned control device maintenance 

activities requiring shutdown. We 

received comments on the 2012 

proposal requesting additional or 

unlimited changes in furnace 

classification. Based on the information 

received, we reevaluated the 

appropriate limit on frequency of 

furnace classification changes. The EPA 

received from one commenter an 

inventory of the number of classification 

changes that occurred each year at a 

specific subpart RRR furnace over a 

nearly 10-year period (available in the 

docket for this rulemaking). The highest 

number of furnace classification 

changes in one year, including both 

planned and unplanned changes, was 

nine. 

Based on the comments and 

information received and because of the 

potential difficulty in distinguishing 

between a planned and unplanned 

change in classification, we are 

proposing and requesting comments on 

a revised limit on the frequency of 

changes in furnace classification of four 

(including the four associated 

reversions) in any 6-month period, 

including both planned and unplanned 

changes in classification, with a 

provision allowing additional changes 

by petitioning the permitting authority 

for major sources, or the Administrator 

for area sources. These revisions in 

proposed 40 CFR 63.1514(e) would 

balance the interest in allowing industry 

to make furnace classification changes 

while preserving the EPA’s and 

delegated authorities’ practical and 

effective enforcement of the emission 

limitations, work practice standards and 

other requirements of subpart RRR. We 

request that any commenter who would 

like the EPA to consider a different limit 

on frequency to include a specific 

rationale and factual basis for why a 

different frequency would be 

appropriate as well as any data on 

historical frequencies of furnace 

classification changes under subpart 

RRR. 

We are specifically requesting 

comments on the revised proposed 

provisions in 40 CFR 63.1514(e), which 

addresses the frequency of changing 

furnace classification. No substantive 

changes have been made to the other 

proposed provisions in 40 CFR 63.1514, 

and we are not requesting comments on 

any other aspect of the proposed 

provisions for furnace classification 

changes. We will address the comments 

previously received on the 2012 

proposal, as well as comments that are 

received in response to the revised 

proposed frequency limit in this 

document, when we take final 

rulemaking action. 

2. Worst Case Scenario Testing 

In the 2012 proposal, we proposed 

amendments to clarify that performance 

tests under multiple scenarios may be 

required in order to reflect the 

emissions ranges for each regulated 

pollutant. We received comments on the 

2012 proposal that the worst case charge 

materials, and blends of these, have 

differing process rates and, therefore, 

the charge rate from the stack tests is not 

representative of the charge rate that 

will be achieved during normal 

operations. Based on the comments 

received and recognizing that it may be 

necessary to conduct performance tests 

under one or multiple scenarios to be 

representative of the range of normal 

operating conditions, we are proposing 

revised language in 40 CFR 

63.1511(b)(1) to clarify the conditions 

under which subpart RRR performance 

tests must be conducted. The intention 

in the subpart RRR rule is to require 

testing under ‘‘worst case’’ conditions 

from the standpoint of emissions and to 

establish parameters based on such 

testing that ensure compliance under all 

operating conditions. For example, in a 

response to comments on the original 

proposed subpart RRR rule regarding 

the inlet temperature requirement for 

fabric filters, the EPA stated that testing 

under worst case conditions, such as 

higher than normal fabric filter inlet 

temperatures, could provide a larger 

temperature operating range, which 

would be used to monitor and ensure 

continuous compliance between 

periodic performance tests (65 FR 

15699, March 23, 2000). In the EPA 

response-to-comments document 

(Summary of Public Comments and 

Responses on Secondary Aluminum 

NESHAP, December 14, 1999, Docket 

No. A–92–61, item V–C–1, comment 

4.1.47), the EPA explained that 

requiring multiple tests over a range of 

different furnace operating conditions 

will show that the selected monitoring 

parameters are valid indicators of 

emissions and that it may not be 

possible for a single test to be 

representative of worst case conditions 

and that more than a single test may be 

required. It is not permissible, for 

example, to demonstrate compliance 

while processing relatively 

uncontaminated scrap, and then at a 

later time, when the supply of this scrap 

is constrained, process more heavily 

contaminated scrap, without 

demonstrating compliance under these 

conditions based on previous emissions 

testing or on new emissions testing if 

previous tests would not be 

representative of the emissions from the 

processing of the more heavily 

contaminated scrap. 

To clarify the requirements for testing, 

we are proposing that performance tests 

be conducted under representative 

(normal) conditions expected to 

produce the highest level of HAP 

emissions expressed in the units of the 

emission standards for the HAP 

(considering the extent of scrap 

contamination, reactive flux addition 

rate and feed/charge rate). If a single test 

condition is not expected to produce the 

highest level of emissions for all HAP, 

testing under two or more sets of 

conditions (for example high 

contamination at low feed/charge rate 

and low contamination at high feed/

charge rate) may be required. Any 

subsequent performance tests for the 

purposes of establishing new or revised 

parametric limits shall be allowed upon 

pre-approval from the permitting 

authority for major sources or the 

Administrator for area sources. These 

new parametric settings shall be used to 

demonstrate compliance for the period 

being tested. We solicit comment on 

whether the proposed amendment 

adequately addresses and clarifies the 

requirement that multiple tests may be 

necessary to represent different 

operational conditions. 

3. Testing of Uncontrolled Furnaces 

As explained in the 2012 proposal, 

while subpart RRR specifies capture and 

collection requirements for emission 

units that are equipped with add-on air 

pollution control devices, there are no 

such requirements for furnaces that are 

not equipped with an add-on air 

pollution control device. To clarify how 

uncontrolled sources are to be tested for 

compliance, in 2012 we proposed 

compliance alternatives for 

uncontrolled affected sources. 

Specifically, in 2012 we proposed either 

the installation of ACGIH hooding or an 

assumption of 67-percent capture 

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efficiency for furnace exhaust (i.e., 

multiply emissions measured at the 

furnace exhaust outlet by 1.5 to 

calculate the total estimated emissions 

from the furnace). Under the 2012 

proposed provisions, if the source fails 

to demonstrate compliance using the 67- 

percent capture efficiency assumption, 

the source would have to retest using 

hooding that meets ACGIH guidelines or 

petition the permitting authority for 

major sources, or the Administrator for 

area sources, that such hoods are 

impractical and propose alternative 

testing procedures that will minimize 

unmeasured fugitive emissions. In the 

2012 proposal, we proposed that the 

retesting would need to occur within 90 

days. 

We received comments that the EPA 

was proposing to mandate ACGIH 

hooding during performance testing for 

uncontrolled furnaces. Commenters also 

provided information that ACGIHcompliant hoods are not possible to 

install on round top furnaces. 

Based on the comments received and 

our consideration of specific testing 

scenarios and types of uncontrolled 

furnaces, we are proposing revised 

requirements for the testing of 

uncontrolled furnaces. In this 

supplemental proposal, we are 

proposing that if the source fails to 

demonstrate compliance by the 

uncontrolled furnace using the 67- 

percent capture efficiency assumption 

proposed in the 2012 proposal, then 

they must retest using ACGIH hooding 

within 180 days (rather than the 90 days 

specified in the 2012 proposal), or the 

source can petition the appropriate 

authority within 180 days that such 

hoods are impracticable and propose 

alternative testing procedures to 

minimize emissions. No time 

constraints on petitioning the 

appropriate authority were specified in 

the 2012 proposal. In this supplemental 

proposal, we are also proposing to 

clarify situations and circumstances 

whereby installation of hooding 

according to ACGIH guidelines would 

be considered impractical and are 

adding examples of procedures for 

minimizing fugitive emissions during 

testing for such situations and 

circumstances. The EPA is proposing 

conditions that would be considered 

impractical to install hooding according 

to ACGIH guidelines. The EPA is also 

proposing alternative procedures to 

minimize fugitive emissions in the 

event that ACGIH-compliant hooding 

cannot be installed. These alternative 

procedures are described in more detail 

below. 

Comments on the 2012 proposal also 

contained information regarding the 

feasibility of installing ACGIHcompliant hooding on certain furnace 

types in preparation for testing. Based 

on our review of the information 

submitted by the commenters, we agree 

that it is not possible to install ACGIHcompliant hoods on round top furnaces 

for testing because the top of the furnace 

would have to be removed by a crane 

operating above the furnace. We also 

agree that case-by-case impracticability 

determinations are not necessary for 

round top furnaces. Consequently, we 

are proposing that existing round top 

furnaces be excluded from the proposed 

requirement either to install ACGIHcompliant hooding or to use a 67- 

percent capture efficiency, as well as 

from the proposed requirement that a 

petition of impracticality be submitted 

to the appropriate authority. Instead, we 

propose that round top furnaces must be 

operated to minimize fugitive emissions 

during testing. We have not received 

any documentation to support requests 

by commenters to exclude other types of 

furnaces such as box reverberatory 

furnaces and box reverberatory furnaces 

with a side door. Therefore, we have not 

proposed to exclude them, but we are 

prepared to evaluate any comments 

submitted regarding impracticality and 

other types of furnaces and, most 

importantly, supporting documentation 

that we may receive from commenters. 

Under this supplemental proposal, 

owners or operators of uncontrolled 

furnaces, including round top furnaces, 

who petition the appropriate authority 

that it is impractical to install ACGIHcompliant hooding would be required to 

minimize fugitive emissions from such 

furnaces during testing. In response to 

commenters’ requests, we are proposing 

example procedures that can be used to 

minimize unmeasured fugitive 

emissions during testing. These 

procedures may include, if practical, 

one or more of the following, but are not 

limited to: 

• Installing a hood that does not 

entirely meet ACGIH guidelines; 

• Using the building as an enclosure 

and measuring emissions exhausted 

from the building if there are no other 

furnaces or other significant sources in 

the building of the pollutants to be 

measured; 

• Installing temporary baffles on the 

sides or top of the furnace opening, if 

it is practical to do so where they will 

not interfere with material handling or 

with the furnace door opening and 

closing; 

• Increasing the exhaust rate from the 

furnace from furnaces with draft fans, so 

as to capture emissions that might 

otherwise escape into the building; 

• Minimizing the time the furnace 

doors are open or the top is off; 

• Delaying gaseous reactive fluxing 

until charging doors are closed or the 

top is on; 

• Agitating or stirring molten metal as 

soon as practicable after salt flux 

addition and closing doors as soon as 

possible after solid fluxing operations, 

including mixing and dross removal; 

• Keeping building doors and other 

openings closed to the greatest extent 

possible to minimize drafts that would 

divert emissions from being drawn into 

the furnace; and 

• Maintaining burners on low-fire or 

pilot operation while the doors are open 

or the top is off. 

We are also proposing revised 

amendments to clarify in what 

circumstances installation of temporary 

capture hoods for testing would be 

considered impractical. We are 

proposing that temporary capture 

hooding installation would be 

considered impractical if: 

• Building or equipment obstructions 

(for example, wall, ceiling, roof, 

structural beams, utilities, overhead 

crane or other) are present such that the 

temporary hood cannot be located 

consistent with acceptable hood design 

and installation practices; 

• Space limitations or work area 

constraints exist such that the 

temporary hood cannot be supported or 

located to prevent interference with 

normal furnace operations or avoid 

unsafe working conditions for the 

furnace operator; or 

• Other obstructions and limitations 

subject to agreement by the permitting 

authority for major sources, or the 

Administrator for area sources. 

We invite comments and solicit 

information on certain aspects of the 

proposed compliance provisions for 

testing of uncontrolled furnaces. 

Specifically, we are soliciting comments 

and information on the requirements in 

this supplemental proposal that specify 

the types of obstacles and limitations 

that can be used to show that testing 

using ACGIH-compliant hooding is 

impractical, the procedures that can be 

implemented to minimize unmeasured 

fugitive emissions during testing, and 

the exemption of existing round top 

furnaces from the requirements to test 

using ACGIH-compliant hooding or 

apply the 67-percent capture efficiency 

assumption. We are not soliciting 

comment on any other element of the 

provisions proposed in the 2012 

proposal regarding testing of 

uncontrolled furnaces. 

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4. Annual Inspections of Capture/

Collection Systems 

In the 2012 proposal, we proposed 

codifying in subpart RRR our existing 

interpretation that annual hood 

inspections include flow rate 

measurements using EPA Reference 

Methods 1 and 2 in Appendix A to 40 

CFR part 60. These flow rate 

measurements supplement the 

effectiveness of the required visual 

inspection for leaks, to reveal the 

presence of obstructions in the 

ductwork, confirm that fan efficiency 

has not declined and provide a 

measured value for air flow. 

Commenters requested that the EPA 

allow flexibility in the methods used to 

complete the annual inspections of 

capture/collection systems stating that 

the use of volumetric flow measurement 

was often not necessary and Method 1 

and 2 tests could be a cost burden for 

some facilities. Comments also 

indicated that routine, but less frequent, 

flow rate measurements could ensure 

that capture/collection systems are 

operated properly and suggested 

alternative methods of ensuring the 

efficiency of capture/collection systems. 

Based on the comments received and 

our consideration of inspection needs, 

the EPA is proposing additional options 

that provide more flexibility in how 

affected sources can verify the efficiency 

of their capture/collection system. 

Instead of annual Methods 1 and 2 

testing, we propose that sources may 

choose to perform flow rate 

measurements using EPA Methods 1 

and 2 once every 5 years provided that 

a flow rate indicator consisting of a pitot 

tube and differential pressure gauge is 

installed and used to record daily the 

differential pressure and to ensure that 

the differential pressure is maintained at 

or above 90 percent of the pressure 

differential measured during the most 

recent Method 2 performance test series, 

and that the flow rate indicator is 

inspected annually. As another option 

to annual flow rate measurements using 

Methods 1 and 2, the EPA is proposing 

to allow Methods 1 and 2 testing to be 

performed every 5 years provided that 

daily measurements of the revolutions 

per minute (RPM) of the capture and 

collection system’s fan are taken, the 

readings are recorded daily and the fan 

RPM is maintained at or above 90 

percent of the RPM measured during the 

most recent Method 2 performance test. 

Further, we are proposing that as an 

alternative to the flow rate 

measurements using Methods 1 and 2, 

the annual hood inspection 

requirements can be satisfied by 

conducting annual verification of a 

permanent total enclosure using EPA 

Method 204. We are further proposing 

that as an alternative to the annual 

verification of a permanent total 

enclosure using EPA Method 204, 

verification can be performed once 

every 5 years if negative pressure in the 

enclosure is directly monitored by a 

pressure indicator and readings are 

recorded daily or the system is 

interlocked to halt material feed should 

the system not operate under negative 

pressure. In this supplemental proposal, 

we are also proposing that readings 

outside a specified range would need to 

be investigated and steps taken to 

restore normal operation, and that 

pressure indicators would need to be 

inspected annually for damage and 

operability. 

5. Sweat Furnace Operating and 

Monitoring Requirements 

We are also proposing to amend 40 

CFR 63.1506(c) and 63.1510(d) to 

provide sweat furnaces with alternative 

compliance options to the ACGIH 

Guidelines and the required annual flow 

rate measurements using EPA Methods 

1 and 2. We are proposing that in lieu 

of meeting the ACGIH guidelines for 

capture and collection and the annual 

flow rate measurements using Methods 

1 and 2, sweat furnaces may comply by 

demonstrating negative air flow into or 

towards the sweat furnace opening as 

well as operating and maintaining the 

sweat furnace in such a way that 

minimizes fugitive emissions. 

6. Startup, Shutdown, Malfunction and 

the Malfunction Affirmative Defense 

In the 2012 proposal, we proposed to 

eliminate provisions that exempt 

sources from the requirement to comply 

with the otherwise applicable CAA 

section 112(d) emission standards 

during periods of Startup, Shutdown 

and Malfunction (SSM). We explained 

in the 2012 proposal that because the 

scrap processed at secondary aluminum 

production facilities is the source of 

emissions, we expect emissions during 

startup and shutdown would be no 

higher, and most likely would be 

significantly lower, than emissions 

during normal operations since no scrap 

is processed during those periods. We 

stated that we knew of no reason why 

the existing standards should not apply 

at all times. For production processes in 

the Secondary Aluminum Production 

source category where the standards are 

expressed in units of pounds per ton of 

feed or similar units (i.e., thermal chip 

dyers, scrap dryer/delacquering kiln/

decoating kilns, dross-only furnaces, inline fluxers using reactive flux and 

group 1 furnaces), the 2012 proposal 

included a method for demonstrating 

compliance with those limits based on 

emissions measured during startup and 

shutdown. 

Because conducting meaningful 

testing during periods of startup and 

shutdown can be problematic, in this 

supplemental proposal we are 

proposing an additional method that 

can be used to demonstrate compliance 

with production based emission limits 

during periods of startup and shutdown. 

Together, these proposed compliance 

provisions for periods of startup and 

shutdown better reflect the MACT 

requirement for those periods. 

Recognizing that the source of HAP 

emissions is the processing of scrap and 

the use of fluxes during processing and 

that the heat for processing in the 

Secondary Aluminum Production 

source category is generated exclusively 

by use of clean fuels—natural gas, 

propane or electricity—we are 

proposing that compliance with 

emission standards during startup and 

shutdown can be demonstrated by 

keeping records that show that the feed/ 

charge rate was zero, the flux rate was 

zero and the affected source or emission 

unit either was heated with electricity, 

propane or natural gas as the sole 

sources of heat or was not heated (see 

proposed section 63.1513(f)). We are 

also proposing that the following 

records be kept: The date and time of 

each startup and shutdown, the quantity 

of feed/charge and flux introduced 

during each startup and shutdown and 

the types of fuel used to heat the unit 

during startup and shutdown. 

We are also proposing to define 

periods of startup and shutdown. For 

the purposes of subpart RRR, startup 

means ‘‘the period of operation for 

thermal chip dryers, scrap dryers/

delacquering kilns, decoating kilns, 

dross-only furnaces, group 1 furnaces, 

in-line fluxers, sweat furnaces and 

group 2 furnaces that begins with 

equipment warming from a cold start or 

a complete shutdown. Startup ends at 

the point that feed/charge is 

introduced.’’ Shutdown means the 

period of operation for thermal chip 

dryers, scrap dryers/delacquering kilns, 

decoating kilns, dross-only furnaces, 

group 1 furnaces, in-line fluxers, sweat 

furnaces and group 2 furnaces that 

begins when the introduction of feed/

charge is halted and all product has 

been removed from the emission unit 

(e.g., by tapping a furnace).’’ 

We solicit comments and additional 

information related to the proposed 

definitions of startup and shutdown, as 

well as the additional option proposed 

in this supplemental proposal for 

demonstrating compliance during 

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periods of startup and shutdown based 

on the presence (or absence) in the 

furnace of feed/charge or fluxing, and 

the type of combustion fuels or the 

absence of combustion fuels. We are 

also proposing to move the 

requirements for compliance 

demonstration during startup and 

shutdown from the emission standards 

section (section 63.1505), where they 

were in the 2012 proposal, to the more 

appropriate compliance demonstration 

section (section 63.1513). However, we 

are not soliciting comments on the 

compliance demonstration method for 

periods of startup and shutdown that 

was presented in the 2012 proposal. 

In the 2012 proposal, we proposed to 

eliminate provisions that exempt 

sources from the requirement to comply 

with the otherwise applicable CAA 

section 112(d) emission standards 

during periods of SSM. We also 

included provisions for affirmative 

defense to civil penalties for violations 

of emission standards caused by 

malfunctions. 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. As explained in the 2012 

proposal (77 FR 8598), 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 United States Court of 

Appeals for the District of Columbia 

Circuit has recognized, the phrase 

‘‘average emissions limitation achieved 

by the best performing 12 percent of’’ 

sources ‘‘says nothing about how the 

performance of the best units is to be 

calculated.’’ Nat’l Ass’n of Clean Water 

Agencies v. EPA, 734 F.3d 1115, 1141 

(D.C. Cir. 2013). While the EPA 

accounts for variability in setting 

emissions standards, nothing in section 

112 requires the agency to consider 

malfunctions as part of that analysis. A 

malfunction should not be treated in the 

same manner as the type of variation in 

performance that occurs during routine 

operations of a source. A malfunction is 

a failure of the source to perform in a 

‘‘normal or usual manner’’ and no 

statutory language compels the EPA to 

consider such events in setting section 

112 standards. 

Further, accounting for malfunctions 

in setting emission standards would be 

difficult, if not impossible, given the 

myriad different types of malfunctions 

that can occur across all sources in the 

category and given the difficulties 

associated with predicting or accounting 

for the frequency, degree and duration 

of various malfunctions that might 

occur. 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-bycase 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 offline as a result of a malfunction (as 

might happen if, for example, the bags 

in a baghouse catch fire) and the 

emission unit is a steady state type unit 

that would take days to shut down, the 

source would go from 99 percent control 

to zero control until the control device 

was repaired. The source’s emissions 

during the malfunction would be 100 

times higher than during normal 

operations. As such, the emissions over 

a 4-day malfunction period would 

exceed the annual emissions of the 

source during normal operations. As 

this example illustrates, accounting for 

malfunctions could lead to standards 

that are not reflective of (and 

significantly less stringent than) levels 

that are achieved by a well-performing 

non-malfunctioning source. It is 

reasonable to interpret section 112 to 

avoid such a result. The EPA’s approach 

to malfunctions is consistent with 

section 112 and is a reasonable 

interpretation of the statute. 

In the event that a source fails to 

comply with the applicable CAA section 

112(d) standards as a result of a 

malfunction event, the EPA would 

determine an appropriate response 

based on, among other things, the good 

faith efforts of the source to minimize 

emissions during malfunction periods, 

including preventative and corrective 

actions, as well as root cause analyses 

to ascertain and rectify excess 

emissions. The EPA would also 

consider whether the source’s failure to 

comply with the CAA section 112(d) 

standard was, in fact, sudden, 

infrequent, not reasonably preventable 

and was not instead caused in part by 

poor maintenance or careless operation. 

If the EPA determines in a particular 

case that 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, 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. 

As noted above, the 2012 proposal 

included an affirmative defense to civil 

penalties for violations caused by 

malfunctions. The EPA included the 

affirmative defense in the 2012 proposal 

as it had in several prior rules 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 

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affirmative defense in the 2012 proposal 

and in several prior rules 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. The United 

States Court of Appeals for the District 

of Columbia Circuit vacated an 

affirmative defense in one of the EPA’s 

section 112(d) regulations. NRDC v. 

EPA, 749 F.3d 1055 (D.C. Cir. 2014) 

(vacating affirmative defense provisions 

in section 112 rule establishing 

emission standards for Portland cement 

kilns). The court found that the EPA 

lacked authority to establish an 

affirmative defense for private civil suits 

and held that under the CAA, the 

authority to determine civil penalty 

amounts in such cases lies exclusively 

with the courts, not the EPA. 

Specifically, the court found: ‘‘As the 

language of the statute makes clear, the 

courts determine, on a case-by-case 

basis, whether civil penalties are 

‘appropriate.’ ’’ See NRDC v. EPA, 749 

F.3d 1055, 1063 (D.C. Cir. 2014) 

(‘‘[U]nder this statute, deciding whether 

penalties are ‘appropriate’ in a given 

private civil suit is a job for the courts, 

not for EPA.’’). In light of NRDC, the 

EPA is withdrawing its proposal to 

include a regulatory affirmative defense 

provision in this rulemaking and in this 

supplementary proposal has eliminated 

section 63.1520 (the provision that 

established the affirmative defense in 

the proposed rule published in the 

Federal Register on February 14, 2012 

(77 FR 8576)). As explained above, if a 

source is unable to comply with 

emissions standards as a result of a 

malfunction, the EPA may use its caseby-case enforcement discretion to 

provide flexibility, as appropriate. 

Further, as the D.C. Circuit recognized, 

in an EPA or citizen enforcement action, 

the court has the discretion to consider 

any defense raised and determine 

whether penalties are appropriate. Cf. 

NRDC v. EPA, 749 F.3d 1055, 1064 (D.C. 

Cir. 2014) (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 logic applies to EPA 

administrative enforcement actions. 

E. What compliance dates are we 

proposing? 

In the 2012 proposal, the EPA 

proposed that owners or operators of 

existing affected sources comply with 

the proposed amendments within 90 

days of the publication of the final rule 

in the Federal Register. Commenters 

stated that the proposed 90 day 

compliance deadline was insufficient 

for sources to comply with certain 

provisions of the final rule. They 

maintained that the rule changes would 

require operational planning, 

maintenance planning, reprogramming 

of data acquisition systems, design and 

installation of hooding equipment and/ 

or negotiations with permitting 

authorities to gain performance test plan 

approvals (with provisions to minimize 

fugitive emissions during testing in 

place of capture hoods). They pointed 

out that facilities that choose to design 

and install capture hoods for 

performance testing will need time to 

design and complete these installations, 

conduct initial performance testing and 

modify their operations, charge 

materials and/or products to ensure 

compliance. Some rule changes, furnace 

switching, HF testing and testing 

uncontrolled furnaces for example, 

would require revisions to operation, 

maintenance and monitoring (OM&M) 

plans as well as to permits to include 

newly established operating parameters 

in cases where changes to furnace 

classifications are made. Commenters 

stated that compliance with HF 

emission standards that may affect 

choice of flux materials, daily 

calculation of HF emissions and 

compliance with SAPU limit that will 

require reprogramming of data systems 

to include HF and/or fluoride 

containing flux composition data would 

also require time to be researched, 

selected, purchased, financed and 

installed. Commenters suggested 

compliance deadlines ranging from 2 to 

3 years. 

The EPA agrees with commenters that 

the proposed 90-day compliance 

deadline is insufficient for sources to 

comply with certain provisions of the 

final rule and is proposing extended 

compliance periods. The EPA is 

proposing a 180-day compliance period 

for the revisions listed in section 

63.1501(d). For the amendments to 

include HF emissions (in section 

63.1505(i)(4) and (k)(2)), the testing of 

existing uncontrolled furnaces (sections 

63.1512(e)(4), (e)(5), (e)(6) and (e)(7)), 

and changing furnace classification 

(section 63.1514), the EPA agrees that a 

longer compliance period is required 

and is proposing a compliance date of 

2 years after promulgation. 

V. Summary of the Revised Cost, 

Environmental and Economic Impacts 

A. What are the affected sources? 

We estimate that there are 161 

secondary aluminum production 

facilities that will be affected by this 

proposed rule. We performed risk 

modeling for 155 of these sources (52 of 

the 53 major sources and 103 of the 108 

area sources). There were six facilities 

that are subject to the Secondary 

Aluminum NESHAP that were not 

included in the risk assessment input 

modeling files. The facilities that were 

not included in the risk assessment 

input files included one major HAP 

source and five area HAP sources. The 

major HAP source was not included 

because the secondary aluminum 

equipment at the source consists of 

group 2 furnaces, for which the EPA did 

not have HAP emissions estimates. The 

five area sources were not included 

because they had no equipment subject 

to D/F emission standards, which are 

the only standards in the NESHAP 

applicable to area sources. We estimate 

that nine secondary aluminum facilities 

have co-located primary aluminum 

operations. The affected sources at 

secondary aluminum production 

facilities include new and existing scrap 

shredders, thermal chip dryers, scrap 

dryer/delacquering kiln/decoating kilns, 

group 2 furnaces, sweat furnaces, drossonly furnaces, rotary dross cooler and 

secondary aluminum processing units 

containing group 1 furnaces and in-line 

fluxers. 

B. What are the air quality impacts? 

No changes are being proposed to 

numerical emissions limits. This 

supplemental proposal affects the 

number of times that a furnace can 

switch operating modes, clarifies how 

uncontrolled furnaces are to conduct 

emissions testing, extends the 

compliance deadline, revises the 

monitoring requirements for annual 

inspection of capture/collection 

systems, clarifies the requirements for 

conducting performance testing under 

worst case conditions and provides 

monitoring alternatives for sweat 

furnaces. These proposed amendments 

would not have any appreciable effect 

on emissions or result in emission 

reductions, although the proposed 

requirements for testing uncontrolled 

furnaces could result in some 

unquantifiable emission reduction. 

Therefore, no quantifiable air quality 

impacts are expected. However, these 

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proposed amendments will help to 

improve compliance, monitoring and 

implementation of the rule. 

C. What are the cost impacts? 

We conservatively estimate the total 

cost of the proposed amendments to be 

$1,711,000 per year (in 2011 dollars). 

However, depending on assumptions 

used for the costs for installing 

temporary hooding for uncontrolled 

furnaces, the estimate of total 

annualized costs could range from 

$611,000 to $2,871,000 per year. 

Our estimate for the source category 

includes an annualized cost of 

$1,200,000 to $3,460,000 for installing 

hooding that meets ACGIH guidelines 

for testing uncontrolled furnaces, 

assuming that 107 furnaces choose that 

option (rather than assuming a 67- 

percent capture efficiency for their 

existing furnace exhaust system). We 

believe that a number of these 107 

furnaces will choose to apply the 67- 

percent assumption rather than install 

hooding. Therefore, these total cost 

estimates are considered conservative 

(more likely to be overestimates rather 

than underestimates) of the total costs to 

the industry. Our estimates of total costs 

also include an annualized cost of 

$11,000 for testing for HF on 

uncontrolled furnaces that are already 

testing for HCl. Finally, we estimate cost 

savings of $600,000 per year for 

furnaces that change furnace operating 

modes and turn off their control 

devices. Our estimate of savings is based 

on 50 furnaces turning off their controls 

for approximately 6 months every year. 

This savings reflects the cost of testing 

(to demonstrate these furnaces remain 

in compliance with emission limits) 

minus the savings realized from 

operating with the control devices 

turned off. 

We estimate that 57 facilities will be 

affected and that the cost per facility 

ranges from negative $36,000 (a cost 

savings) per year for a facility changing 

furnace operating modes to $216,500 

per year for a facility installing hooding 

for testing. 

The estimated costs are explained 

further in the document titled Updated 

Cost Estimates for the Proposed Rule 

Changes to Secondary Aluminum 

NESHAP, which is available in the 

docket for this action. 

D. What are the economic impacts? 

We performed an economic impact 

analysis for the proposed revisions and 

amendments in this supplemental 

proposed rulemaking. This analysis 

estimates impacts based on using 

annualized cost-to-sales ratios for 

affected firms. For the 28 parent firms 

affected by this proposed rule, the costto-sales estimate for each parent firm is 

less than 0.1 percent. For more 

information, please refer to the 

document titled Economic Impact 

Analysis for the Secondary Aluminum 

Supplemental Proposal, which is 

available in the docket. 

E. What are the benefits? 

We do not anticipate any significant 

reductions in HAP emissions as a result 

of these proposed amendments. 

However, we think that the proposed 

amendments will help to improve the 

clarity of the rule, which can improve 

compliance and minimize emissions. 

Certain provisions also provide 

operational flexibility with no increase 

in HAP emissions. 

VI. Request for Comments 

As discussed in detail above, we 

solicit comments on the revised risk 

assessment and proposed changes 

presented in this supplemental 

proposal. We are not re-opening 

comment on any other elements of the 

2012 proposal (77 FR 8576, February 14, 

2012). Comments previously received 

on the 2012 proposal, along with 

comments received on and within the 

scope of this supplemental proposal, 

will be addressed in the final 

rulemaking action. 

We are also interested in any 

additional data that may help to reduce 

the uncertainties inherent in the risk 

assessments and other analyses. We are 

specifically interested in receiving 

corrections to 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 on the RTR Web page at 

http://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®

Access format and all accompanying 

documentation to Docket ID No. EPA– 

HQ–OAR–2010–0544 (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® Excel files that are 

generated by the Microsoft® Access file. 

These files are provided on the RTR 

Web page at http://www.epa.gov/ttn/

atw/rrisk/rtrpg.html. 

VIII. Statutory and Executive Order 

Reviews 

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’’ under the terms of 

Executive Order 12866 (58 FR 51735, 

October 4, 1993) and is, therefore, not 

subject to review under Executive 

Orders 12866 and 13563 (76 FR 3821, 

January 21, 2011). 

B. Paperwork Reduction Act 

The information collection 

requirements in this proposed action 

have been submitted for approval to 

OMB under the Paperwork Reduction 

Act, 44 U.S.C. 3501 et seq. The ICR 

document prepared by the EPA has been 

assigned the EPA ICR number 2453.01. 

We are proposing changes to the 

paperwork requirements to the 

Secondary Aluminum Production 

source category that were proposed in 

2012. 

In addition, in the 2012 proposal, we 

included an estimate of the burden 

associated with the affirmative defense 

in the ICR. However, as explained 

above, we are withdrawing our proposal 

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to include affirmative defense 

provisions, and the burden estimate has 

been revised accordingly. 

We estimate 161 regulated entities are 

currently subject to subpart RRR. The 

annual monitoring, reporting and 

recordkeeping burden for this collection 

(averaged over the first 3 years after the 

effective date of the standards) for these 

amendments to subpart RRR is 

estimated to be $2,990,000 per year. 

This includes 1,694 labor hours per year 

at a total labor cost of $162,000 per year, 

and total non-labor capital and 

operation and maintenance (O&M) costs 

of $2,828,000 per year. The total burden 

for the federal government (averaged 

over the first 3 years after the effective 

date of the standard) is estimated to be 

271 labor hours per year at an annual 

cost of $12,231. Burden is defined at 5 

CFR 1320.3(b). 

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–2010–0544. 

Submit any comments related to the ICR 

to the EPA and OMB. See the ADDRESSES

section at the beginning of this 

document for where to submit 

comments to the EPA. Send comments 

to OMB at the Office of Information and 

Regulatory Affairs, Office of 

Management and Budget, 725 17th 

Street NW., Washington, DC 20503, 

Attention: Desk Office for the EPA. 

Since OMB is required to make a 

decision concerning the ICR between 30 

and 60 days after December 8, 2014, a 

comment to OMB is best assured of 

having its full effect if OMB receives it 

by January 7, 2015. The final rule will 

respond to any OMB or public 

comments on the information collection 

requirements contained in this proposal. 

C. Regulatory Flexibility Act 

The Regulatory Flexibility Act (RFA) 

generally requires an agency to prepare 

a regulatory flexibility analysis of any 

rule subject to notice and comment 

rulemaking requirements under the 

Administrative Procedure Act, or any 

other statute, unless the agency certifies 

that the rule will not have a significant 

economic impact on a substantial 

number of small entities. Small entities 

include small businesses, small 

organizations and small governmental 

jurisdictions. 

For purposes of assessing the impacts 

of this action on small entities, small 

entity is defined as: (1) A small business 

as defined by the Small Business 

Administration’s (SBA) regulations at 13 

CFR 121.201; (2) a small governmental 

jurisdiction that is a government of a 

city, county, town, school district or 

special district with a population of less 

than 50,000; and (3) a small 

organization that is any not-for-profit 

enterprise that is independently owned 

and operated and is not dominant in its 

field. For this source category, which 

has the NAICS code 331314 (i.e., 

Secondary Smelting and Alloying of 

Aluminum), the SBA small business 

size standard is 750 employees 

according to the SBA small business 

standards definitions. 

After considering the economic 

impacts of these proposed changes on 

small entities, I certify that this action 

will not have a significant economic 

impact on a substantial number of small 

entities. We determined in the economic 

and small business analysis that, using 

the results from the cost memorandum, 

28 entities will incur costs associated 

with the proposed rule. Of these 28 

entities, nine of them are small. Of these 

nine, all of them are estimated to 

experience a negative cost (i.e., a cost 

savings) as a result of the proposed 

action according to our analysis. For 

more information, please refer to the 

Economic Impact Analysis for the 

Secondary Aluminum Supplemental 

Proposal, which is available in the 

docket. 

D. Unfunded Mandates Reform Act 

This action does not contain a Federal 

mandate that may result in expenditures 

of $100 million or more for state, local 

and tribal governments, in the aggregate, 

or the private sector in any one year. 

Thus, this action is not subject to the 

requirements of section 202 or 205 of 

the Unfunded Mandates Reform Act 

(UMRA). 

This action is also not subject to the 

requirements of section 203 of UMRA 

because it contains no regulatory 

requirements that might significantly or 

uniquely affect small governments as it 

contains no requirements that apply to 

such governments nor does it impose 

obligations upon them. 

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, as specified in 

Executive Order 13132. None of the 

facilities subject to this proposed action 

are owned or operated by state 

governments. Thus, Executive Order 

13132 does not apply to this proposed 

action. 

In the spirit of Executive Order 13132, 

and consistent with the EPA policy to 

promote communications between the 

EPA and State and local governments, 

the EPA specifically solicits comment 

on this proposed rule from state and 

local officials. 

F. Executive Order 13175: Consultation 

and Coordination With Indian Tribal 

Governments 

This action does not have tribal 

implications, as specified in Executive 

Order 13175 (65 FR 67249, November 9, 

2000). There are no secondary 

aluminum production facilities that are 

owned or operated by tribal 

governments. Thus, Executive Order 

13175 does not apply to this action. The 

EPA specifically solicits additional 

comments on this proposed action from 

tribal officials. 

G. Executive Order 13045: Protection of 

Children From Environmental Health 

Risks and Safety Risks 

This action is not subject to Executive 

Order 13045 (62 FR 19885, April 23, 

1997) because it is not economically 

significant as defined in Executive 

Order 12866 and because the agency 

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 

and IV of this document. The public is 

invited to submit comments or identify 

peer-reviewed studies and data that 

assess effects of early life exposures to 

the pollutants emitted by this source 

category. 

H. Executive Order 13211: Actions 

Concerning Regulations That 

Significantly Affect Energy Supply, 

Distribution, or Use 

This action is not subject to Executive 

Order 13211 (66 FR 28355, May 22, 

2001) because it is not a significant 

regulatory action under Executive Order 

12866. 

I. National Technology Transfer and 

Advancement Act 

Section 12(d) of the National 

Technology Transfer and Advancement 

Act of 1995 (‘‘NTTAA’’), Public Law 

104–113 (15 U.S.C. 272 note), directs 

the EPA to use voluntary consensus 

standards (VCS) in its regulatory 

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activities unless to do so would be 

inconsistent with applicable law or 

otherwise impractical. VCS are 

technical standards (e.g., materials 

specifications, test methods, sampling 

procedures and business practices) that 

are developed or adopted by VCS 

bodies. NTTAA directs the EPA to 

provide Congress, through OMB, 

explanations when the agency decides 

not to use available and applicable VCS. 

This proposed action involves 

technical standards. Therefore, the 

agency conducted a search to identify 

potentially applicable VCS. The VCS 

ASTM D7520–09, ‘‘Standard Test 

Method for Determining the Opacity of 

a Plume in the Outdoor Ambient 

Atmosphere’’ was identified as an 

acceptable alternative to EPA Method 9. 

The standard was developed and is 

published by the American Society for 

Testing and Materials (ASTM). The 

standard can be obtained by contacting 

ASTM at 100 Barr Harbor Drive, Post 

Office Box C700, West Conshohocken, 

PA 19428–2959 or at their Web site, 

http://www.astm.org. 

In addition, as a result of comments 

received on the 2012 proposal, EPA 

Method 26 was identified as a 

reasonable alternative to EPA Method 

26A and EPA Method 204 was 

identified as a reasonable alternative 

method for EPA Methods 1 and 2. The 

EPA agrees that EPA Methods 26 and 

204 are acceptable alternatives for use in 

this rule. Therefore, the EPA has 

proposed adding ASTM D7520–09, 

‘‘Standard Test Method for Determining 

the Opacity of a Plume in the Outdoor 

Ambient Atmosphere,’’ as an alternative 

method for the currently required EPA 

Method 9; EPA Method 26 as an 

alternative for the currently required 

EPA Method 26A; and EPA Method 204 

as an alternative to the currently 

required EPA Methods 1 and 2. 

The EPA welcomes comments on this 

aspect of the proposed rulemaking and, 

specifically, invites the public to 

identify potentially-applicable VCS and 

to explain why such standards should 

be used in this regulation. 

J. Executive Order 12898: Federal 

Actions To Address Environmental 

Justice in Minority Populations and 

Low-Income Populations 

Executive Order 12898 (59 FR 7629, 

February 16, 1994) establishes federal 

executive policy on environmental 

justice. Its main provision directs 

federal agencies, to the greatest extent 

practicable and permitted by law, to 

make environmental justice part of their 

mission by identifying and addressing, 

as appropriate, disproportionately high 

and adverse human health or 

environmental effects of their programs, 

policies and activities on minority 

populations and low-income 

populations in the United States. 

The EPA has determined that this 

proposed rule will not have 

disproportionately high and adverse 

human health or environmental effects 

on minority or low-income populations 

because it does not affect the level of 

protection provided to human health or 

the environment. This proposed rule 

will not relax the emission limits on 

regulated sources and will not result in 

emissions increases. 

Because our residual risk assessment 

determined that there was minimal 

residual risk associated with the 

emissions from facilities in this source 

category, a demographic risk analysis 

was not necessary for this category. 

However, the EPA did conduct a 

proximity analysis for both area and 

major sources. The results of these 

analyses are summarized in section 

IV.A.6 of this notice and in more detail 

in the EJ Screening Report for Area 

Sources and the EJ Screening Report for 

Major Sources, which are available in 

the docket for this rulemaking. 

List of Subjects in 40 CFR Part 63 

Environmental protection, Air 

pollution control, Reporting and 

recordkeeping requirements. 

Dated: November 13, 2014. 

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 SOURCES 

CATEGORIES 

■ 1. The authority citation for part 63 

continues to read as follows: 

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

Subpart RRR—NATIONAL EMISSION 

STANDARDS FOR HAZARDOUS AIR 

POLLUTANTS FOR SECONDARY 

ALUMINUM PRODUCTION 

■ 2. Section 63.1501 is amended by 

adding paragraphs (d), (e), and (f) to 

read as follows: 

§ 63.1501 Dates. 

* * * * * 

(d) The owner or operator of an 

existing affected source must comply 

with the following requirements of this 

subpart by [DATE 180 DAYS FROM 

PUBLICATION OF THE FINAL RULE 

IN THE Federal Register]: § 63.1505 (k) 

introductory text, (k)(1) through (k)(5), 

other than the emission standards for 

HF in (k)(2); § 63.1506 (a)(1), (c)(1), 

(g)(5), (k)(3), (m)(4), (n)(1); § 63.1510, 

(b)(5), (b)(9), (d)(2), (d)(3), (f)(1)(ii), 

(i)(4), (j)(4), (n)(1), (o)(1), (o)(1)(ii), 

(s)(2)(iv), (t) introductory text, (t)(2)(i), 

(t)(2)(ii), (t)(4), (t)(5); § 63.1511(a) 

introductory text, (b) introductory text, 

(b)(1), (b)(6), (c)(9), (f)(6), (g)(5); 

§ 63.1512(e)(1), (e)(2), (e)(3), (h)(2), (j), 

(j)(1)(i), (j)(2)(i), (o)(1), (p)(2); 

§ 63.1513(b) introductory text, (b)(1), 

(e)(1), (e)(2), (e)(3), (f); § 63.1516 (b) 

introductory text, (b)(2)(iii), (b)(3), (d); 

§ 63.1517(b)(16)(i), (b)(18), (b)(19), (c). 

(e) The owner or operator of an 

existing affected source must comply 

with the following requirements of this 

subpart by [DATE 2 YEARS FROM 

PUBLICATION OF THE FINAL RULE 

IN THE Federal Register]: 

§ 63.1505(i)(4) and (k)(2) emission 

standards for HF; § 63.1512(e)(4) 

through (7) requirements for testing 

existing uncontrolled group 1 furnaces; 

and § 63.1514 requirements for change 

of furnace classification. 

(f) The owner or operator of a new 

affected source that commences 

construction or reconstruction after 

February 14, 2012 must comply with all 

of the requirements listed in paragraphs 

(d) and (e) of this section by [DATE OF 

PUBLICATION OF THE FINAL RULE 

IN THE Federal Register] or upon 

startup, whichever is later. 

■ 3. Section 63.1503 is amended by 

adding in alphabetical order definitions 

for ‘‘round top furnace,’’ ‘‘shutdown,’’ 

and ‘‘startup’’ to read as follows: 

§ 63.1503 Definitions. 

* * * * * 

Round top furnace means a 

cylindrically-shaped reverberatory 

furnace that has a top that is removed 

for charging and other furnace 

operations. 

* * * * * 

Shutdown means the period of 

operation for thermal chip dryers, scrap 

dryers/delacquering kilns, decoating 

kilns, dross-only furnaces, group 1 

furnaces, in-line fluxers, sweat furnaces 

and group 2 furnaces that begins when 

the introduction of feed/charge is halted 

and all product has been removed from 

the emission unit (e.g., by tapping a 

furnace). 

* * * * * 

Startup means the period of operation 

for thermal chip dryers, scrap dryers/

delacquering kilns, decoating kilns, 

dross-only furnaces, group 1 furnaces, 

in-line fluxers, sweat furnaces and 

group 2 furnaces that begins with 

equipment warming from a cold start or 

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a complete shutdown. Startup ends at 

the point that feed/charge is introduced. 

* * * * * 

■ 4. Section 63.1506 is amended by 

adding paragraph (c)(4) to read as 

follows: 

§ 63.1506 Operating requirements. 

* * * * * 

(c) * * * 

(4) In lieu of paragraph (c)(1) of this 

section, the owner or operator of a sweat 

furnace may design, install and operate 

each sweat furnace in accordance with 

paragraphs (c)(4)(i) through (iii) of this 

section. 

(i) As demonstrated by an annual 

negative air flow test conducted in 

accordance with § 63.1510(d)(3), air 

flow must be into the sweat furnace or 

towards the plane of the sweat furnace 

opening. 

(ii) The owner or operator must 

maintain and operate the sweat furnace 

in a manner consistent with the good 

practices requirements for minimizing 

emissions, including fugitive emissions, 

in paragraph (a)(5) of this section. 

Procedures that will minimize fugitive 

emissions may include, but are not 

limited to the following: 

(A) Increasing the exhaust rate from 

the furnace with draft fans, so as to 

capture emissions that might otherwise 

escape from the sweat furnace opening; 

(B) Minimizing the time the sweat 

furnace doors are open; 

(C) Keeping building doors and other 

openings closed to the greatest extent 

possible to minimize drafts that would 

divert emissions from being drawn into 

the sweat furnace; 

(D) Maintaining burners on low-fire or 

pilot operation while the doors are 

open; 

(E) Conducting periodic inspections 

and maintenance of sweat furnace 

components to ensure their proper 

operation and performance including 

but not limited to, door assemblies, 

seals, combustion chamber refractory 

material, afterburner and stack 

refractory, blowers, fans, dampers, 

burner tubes, door raise cables, pilot 

light assemblies, baffles, sweat furnace 

and afterburner shells and other internal 

structures. 

(iii) The owner or operator must 

document in their OM&M plan the 

procedures to be used to minimize 

emissions, including fugitive emissions, 

in addition to the procedures to ensure 

the proper operation and maintenance 

of the sweat furnace. 

* * * * * 

■ 5. Section 63.1510 is amended by 

revising paragraph (d)(2) and adding 

paragraph (d)(3) to read as follows: 

§ 63.1510 Monitoring requirements. 

* * * * * 

(d) * * * 

(2) Inspect each capture/collection 

and closed vent system at least once 

each calendar year to ensure that each 

system is operating in accordance with 

the operating requirements in 

§ 63.1506(c) and record the results of 

each inspection. This inspection shall 

include a volumetric flow rate 

measurement taken at a location in the 

ductwork downstream of the hoods that 

is representative of the actual 

volumetric flow rate without 

interference due to leaks, ambient air 

added for cooling or ducts from other 

hoods. The flow rate measurement must 

be performed in accordance with 

paragraphs (d)(2)(i), (ii), or (iii) of this 

section. As an alternative to the flow 

rate measurement specified in this 

paragraph, the inspection may satisfy 

the requirements of this paragraph, 

including the operating requirements in 

§ 63.1506(c), by including permanent 

total enclosure verification in 

accordance with (d)(2)(i) or (iv) of this 

section. 

(i) Conduct annual flow rate 

measurements using EPA Methods 1 

and 2 in Appendix A to 40 CFR part 60, 

or conduct annual verification of a 

permanent total enclosure using EPA 

Method 204; or 

(ii) As an alternative to annual flow 

rate measurements using EPA Methods 

1 and 2, measurement with EPA 

Methods 1 and 2 can be performed once 

every 5 years, provided that: 

(A) A flow rate indicator consisting of 

a pitot tube and differential pressure 

gauge (Magnehelic®, manometer or 

other differential pressure gauge) is 

installed with the pitot tube tip located 

at a representative point of the duct 

proximate to the location of the 

Methods 1 and 2 measurement site; and 

(B) The flow rate indicator is installed 

and operated in accordance with the 

manufacturer’s specifications; and 

(C) The differential pressure is 

recorded during the Method 2 

performance test series; and 

(D) Differential pressure readings are 

recorded daily, and maintained at or 

above 90 percent of the pressure 

differential indicated by the flow rate 

indicator during the most recent Method 

2 performance test series; and 

(E) An inspection of the pitot tube and 

associated lines for damage, plugging, 

leakage and operational integrity is 

conducted at least once per year; or 

(iii) As an alternative to annual flow 

rate measurements using EPA Methods 

1 and 2, measurement with EPA 

Methods 1 and 2 can be performed once 

every 5 years, provided that: 

(A) Daily measurements of the capture 

and collection system’s fan revolutions 

per minute (RPM) are made by taking 

three measurements with at least 5 

minutes between each measurement, 

and averaging the three measurements; 

and 

(B) Readings are recorded daily and 

maintained at or above 90 percent of the 

RPM measured during the most recent 

Method 2 performance test series. 

(iv) As an alternative to the annual 

verification of a permanent total 

enclosure using EPA Method 204, 

verification can be performed once 

every 5 years, provided that: 

(A) Negative pressure in the enclosure 

is directly monitored by a pressure 

indicator installed at a representative 

location; 

(B) Pressure readings are recorded 

daily or the system is interlocked to halt 

material feed should the system not 

operate under negative pressure; 

(C) When there are readings outside 

the range specified in the OM&M plan, 

the facility investigates and takes steps 

to restore normal operation, which may 

include initial inspection and 

evaluation, recording that operations 

returned to normal without operator 

action or other applicable actions; and 

(D) An inspection of the pressure 

indicator for damage and operational 

integrity is conducted at least once per 

calendar year. 

(3) In lieu of paragraph (d)(2) of this 

section, the owner or operator of a sweat 

furnace may inspect each sweat furnace 

at least once each calendar year to 

ensure that they are being operated in 

accordance with the negative air flow 

requirements in § 63.1506(c)(4). The 

owner or operator of a sweat furnace 

must demonstrate negative air flow into 

the sweat furnace in accordance with 

paragraphs (d)(3)(i) through (iii) of this 

section. 

(i) Perform an annual visual smoke 

test to demonstrate airflow into the 

sweat furnace or towards the plane of 

the sweat furnace opening; 

(ii) Perform the smoke test using a 

smoke source, such as a smoke tube, 

smoke stick, smoke cartridge, smoke 

candle or other smoke source that 

produces a persistent and neutral 

buoyancy aerosol; and 

(iii) Perform the visual smoke test at 

a safe distance from and near the center 

of the sweat furnace opening. 

* * * * * 

■ 6. Section 63.1511 is amended by 

revising paragraph (b)(1) to read as 

follows: 

§ 63.1511 Performance test/compliance 

demonstration general requirements. 

* * * * * 

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(b) * * * 

(1) The performance tests must be 

conducted under representative 

(normal) conditions expected to 

produce the highest level of HAP 

emissions expressed in the units of the 

emission standards for the HAP 

(considering the extent of scrap 

contamination, reactive flux addition 

rate and feed/charge rate). If a single test 

condition is not expected to produce the 

highest level of emissions for all HAP, 

testing under two or more sets of 

conditions (for example high 

contamination at low feed/charge rate, 

and low contamination at high feed/

charge rate) may be required. Any 

subsequent performance tests for the 

purposes of establishing new or revised 

parametric limits shall be allowed upon 

pre-approval from the permitting 

authority for major sources, or the 

Administrator for area sources. These 

new parametric settings shall be used to 

demonstrate compliance for the period 

being tested. 

* * * * * 

■ 7. Section 63.1512 is amended by 

adding paragraphs (e)(4) through (7) to 

read as follows: 

§ 63.1512 Performance test/compliance 

demonstration requirements and 

procedures. 

* * * * * 

(e) * * * 

(4) When testing an existing 

uncontrolled furnace, the owner or 

operator must comply with the 

requirements of either paragraphs 

(e)(4)(i) or (ii) of this section at the next 

required performance test. 

(i) Install hooding that meets ACGIH 

Guidelines, or 

(ii) Assume a 67-percent capture 

efficiency for the furnace exhaust (i.e., 

multiply emissions measured at the 

furnace exhaust outlet by 1.5). If the 

source fails to demonstrate compliance 

using the 67-percent capture efficiency 

assumption, the owner or operator must 

re-test with a hood that meets the 

ACGIH Guidelines within 180 days, or 

petition the permitting authority for 

major sources, or the Administrator for 

area sources, within 180 days that such 

hoods are impractical under the 

provisions of paragraph (e)(6) of this 

section and propose testing procedures 

that will minimize fugitive emissions 

during the performance test according to 

paragraph (e)(7) of this section. 

(iii) Existing round top furnaces are 

exempt from the requirements of 

paragraphs (e)(4)(i) and (ii) of this 

section. Round top furnaces must be 

operated to minimize fugitive emissions 

according to paragraph (e)(7) of this 

section. 

(5) When testing a new uncontrolled 

furnace the owner or operator must: 

(i) Install hooding that meets ACGIH 

Guidelines or petition the permitting 

authority for major sources, or the 

Administrator for area sources, that 

such hoods are impracticable under the 

provisions of paragraph (e)(6) of this 

section and propose testing procedures 

that will minimize fugitive emissions 

during the performance test according to 

the provisions of paragraph (e)(7); and 

(ii) Subsequent testing must be 

conducted in accordance with 

paragraphs (e)(4)(i) and (ii) of this 

section. 

(6) The installation of hooding that 

meets ACGIH Guidelines is considered 

impractical if any of the following 

conditions exist: 

(i) Building or equipment obstructions 

(for example, wall, ceiling, roof, 

structural beams, utilities, overhead 

crane or other obstructions) are present 

such that the temporary hood cannot be 

located consistent with acceptable hood 

design and installation practices; 

(ii) Space limitations or work area 

constraints exist such that the 

temporary hood cannot be supported or 

located to prevent interference with 

normal furnace operations or avoid 

unsafe working conditions for the 

furnace operator; or 

(iii) Other obstructions and 

limitations subject to agreement of the 

permitting authority for major sources, 

or the Administrator for area sources. 

(7) Testing procedures that will 

minimize fugitive emissions may 

include, but are not limited to the 

following: 

(i) Installing a hood that does not 

entirely meet ACGIH guidelines; 

(ii) Using the building as an 

enclosure, and measuring emissions 

exhausted from the building if there are 

no other furnaces or other significant 

sources in the building of the pollutants 

to be measured; 

(iii) Installing temporary baffles on 

those sides or top of furnace opening if 

it is practical to do so where they will 

not interfere with material handling or 

with the furnace door opening and 

closing; 

(iv) Increasing the exhaust rate from 

the furnace with draft fans, so as to 

capture emissions that might otherwise 

escape into the building if it can be 

done without increasing furnace 

emissions in a way that make the test 

non-representative; 

(v) Minimizing the time the furnace 

doors are open or the top is off; 

(vi) Delaying gaseous reactive fluxing 

until charging doors are closed and, for 

round top furnaces, until the top is on; 

(vii) Agitating or stirring molten metal 

as soon as practicable after salt flux 

addition and closing doors as soon as 

possible after solid fluxing operations, 

including mixing and dross removal; 

(viii) Keeping building doors and 

other openings closed to the greatest 

extent possible to minimize drafts that 

would divert emissions from being 

drawn into the furnace; or 

(ix) Maintaining burners on low-fire 

or pilot operation while the doors are 

open or the top is off. 

* * * * * 

■ 8. Section 63.1513 is amended by 

adding paragraph (f) to read as follows: 

§ 63.1513 Equations for determining 

compliance. 

* * * * * 

(f) Periods of startup and shutdown. 

For a new or existing affected source, or 

a new or existing emission unit subject 

to an emissions limit in paragraphs 

§ 63.1505(b) through (j) expressed in 

units of pounds per ton of feed/charge, 

or mg TEQ or ng TEQ per Mg of feed/ 

charge, demonstrate compliance during 

periods of startup and shutdown in 

accordance with paragraph (f)(1) of this 

section or determine your emissions per 

unit of feed/charge during periods of 

startup and shutdown in accordance 

with paragraph (f)(2) of this section. 

Startup and shutdown emissions for 

group 1 furnaces and in-line fluxers 

must be calculated individually, and not 

on the basis of a SAPU. Periods of 

startup and shutdown are excluded 

from the calculation of SAPU emission 

limits in § 63.1505(k), the SAPU 

monitoring requirements in § 63.1510(t) 

and the SAPU emissions calculations in 

§ 63.1513(e). 

(1) For periods of startup and 

shutdown, records establishing a feed/

charge rate of zero, a flux rate of zero, 

and that the affected source or emission 

unit was either heated with electricity, 

propane or natural gas as the sole 

sources of heat or was not heated, may 

be used to demonstrate compliance with 

the emission limit, or 

(2) For periods of startup and 

shutdown, divide your measured 

emissions in lb/hr or mg/hr or ng/hr by 

the feed/charge rate in tons/hr or Mg/hr 

from your most recent performance test 

associated with a production rate greater 

than zero, or the rated capacity of the 

affected source if no prior performance 

test data is available. 

■ 9. Amend section 63.1514, as 

proposed to be added at 77 FR 8576 

(February 14, 2012), by revising 

paragraph (e) to read as follows: 

§ 63.1514 Change of furnace classification. 

* * * * * 

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(e) Limit on Frequency of changing 

furnace operating mode. 

(1) Changing furnace operating mode 

including reversion to the previous 

mode, as provided in paragraphs (a) 

through (d) of this section, may not be 

done more frequently than 4 times in 

any 6-month period. 

(2) If additional changes are needed, 

the owner or operator must apply in 

advance to the permitting authority, for 

major sources, or the Administrator, for 

area sources, for approval. 

■ 10. Section 63.1517 is amended by 

adding paragraphs (b)(18) and (19) to 

read as follows: 

§ 63.1517 Records. 

* * * * * 

(b) * * * 

(18) For each period of startup or 

shutdown for which the owner or 

operator chooses to demonstrate 

compliance for an affected source based 

on a feed/charge rate of zero, a flux rate 

of zero and the use of electricity, 

propane or natural gas as the sole 

sources of heating or the lack of heating, 

the owner or operator must maintain the 

following records: 

(i) The date and time of each startup 

and shutdown, 

(ii) The quantities of feed/charge and 

flux introduced during each startup and 

shutdown, and 

(iii) The types of fuel used to heat the 

unit, or that no fuel was used, during 

startup and shutdown. 

(19) For owners or operators that 

choose to change furnace operating 

modes, the following records must be 

maintained: 

(i) The date and time of each change 

in furnace operating mode, and 

(ii) The nature of the change in 

operating mode (for example, group 1 

controlled furnace processing other than 

clean charge to group 2). 

■ 11. Table 2 to subpart RRR of part 63 

is amended by revising the entry for 

‘‘All affected sources and emission units 

with an add-on air pollution control 

device’’ to read as follows: 

TABLE 2 TO SUBPART RRR OF PART 63—SUMMARY OF OPERATING REQUIREMENTS FOR NEW AND EXISTING AFFECTED

SOURCES AND EMISSION UNITS

Affected source/emission unit Monitor type/operation/process Operating requirements 

All affected sources and emission units 

with an add-on air pollution control 

device.

Emission capture and collection system Design and install in accordance with ACGIH Guidelines; 

operate in accordance with OM&M plan (sweat furnaces 

may be operated according to 63.1506(c)(4)).b

* * * * * * * 

* * * * * 

bOM&M plan—Operation, maintenance, and monitoring plan. 

* * * * * 

■ 12. Table 3 to subpart RRR of part 63 

is amended by revising the entry for 

‘‘All affected sources and emission units 

with an add-on air pollution control 

device’’ and revising footnote d to Table 

3 to read as follows: 

TABLE 3 TO SUBPART RRR OF PART 63—SUMMARY OF MONITORING REQUIREMENTS FOR NEW AND EXISTING AFFECTED

SOURCES AND EMISSION UNITS

Affected source/emission unit Monitor type/operation/process Monitoring requirements 

All affected sources and emission units 

with an add-on air pollution control 

device.

Emission capture and collection system Annual inspection of all emission capture, collection, and 

transport systems to ensure that systems continue to operate in accordance with ACGIH Guidelines. Inspection 

includes volumetric flow rate measurements or verification 

of a permanent total enclosure using EPA Method 204.d

* * * * * * * 

dThe frequency of volumetric flow rate measurements may be decreased to once every 5 years if daily differential pressure measures or daily 

fan RPM measurements are made in accordance with § 63.1510(d)(ii) and (iii). The frequency of annual verification of a permanent total enclosure may be decreased to once every 5 years if negative pressure measurements in the enclosure are made daily in accordance with 

§ 63.1510(d)(iv). In lieu of volumetric flow rate measurements or verification of permanent total enclosure, sweat furnaces may demonstrate annually negative air flow into the sweat furnace opening in accordance with § 63.1510(d)(3). 

[FR Doc. 2014–27497 Filed 12–5–14; 8:45 am] 

BILLING CODE 6560–50–P 

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