72914 Federal Register / Vol. 79, No. 235 / Monday, December 8, 2014 / Proposed Rules 

ENVIRONMENTAL PROTECTION 

AGENCY 

40 CFR Part 63 

[EPA–HQ–OAR–2011–0797; FRL–9917–44– 

OAR] 

RIN 2060–AQ92 

National Emissions Standards for 

Hazardous Air Pollutants: Primary 

Aluminum Reduction Plants 

AGENCY: Environmental Protection 

Agency. 

ACTION: Supplemental proposed 

rulemaking. 

SUMMARY: This action supplements our 

proposed amendments to the national 

emission standards for hazardous air 

pollutants (NESHAP) for the Primary 

Aluminum Production source category 

published in the Federal Register on 

December 6, 2011. In that action, the 

Environmental Protection Agency (EPA) 

proposed amendments based on the 

initial residual risk and technology 

reviews (RTR) for this source category, 

and also proposed certain emission 

limits reflecting performance of 

Maximum Achievable Control 

Technology (MACT). Today’s action 

reflects a revised technology review and 

a revised residual risk analysis for the 

Primary Aluminum Production source 

category and proposes new and revised 

emission standards based on those 

analyses, newly obtained emissions test 

data, and comments we received in 

response to the 2011 proposal, 

including certain revisions to the 

technology-based standards reflecting 

performance of MACT. This action also 

proposes new compliance requirements 

to meet the revised standards. This 

action, if adopted, will provide 

improved environmental protection 

regarding potential emissions of 

hazardous air pollutant (HAP) emissions 

from primary aluminum production 

facilities. 

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 to speak at a public 

hearing by December 15, 2014, a public 

hearing will be held 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–2011–0797, 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–2011–0797 in the subject line 

of the message. 

• Fax: (202) 566–9744. Attention 

Docket ID No. EPA–HQ–OAR–2011– 

0797. 

• Mail: Environmental Protection 

Agency, EPA Docket Center (EPA/DC), 

Mail Code: 28221T, Attention Docket ID 

No. EPA–HQ–OAR–2011–0797, 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–2011– 

0797. 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–2011– 

0797. 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 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–2011–0797. All 

documents in the docket are listed in 

the regulations.gov index. Although 

listed in the index, some information is 

not publicly available, e.g., CBI or other 

information whose disclosure is 

restricted by statute. Certain other 

material, such as copyrighted material, 

is not placed on the internet and will be 

publicly available only in hard copy. 

Publicly available docket materials are 

available either electronically in 

regulations.gov or in hard copy at the 

EPA Docket Center, Room 3334, EPA 

WJC West Building, 1301 Constitution 

Avenue NW., Washington, DC. The 

Public Reading Room is open from 8:30 

a.m. to 4:30 p.m., Monday through 

Friday, excluding legal holidays. The 

telephone number for the Public 

Reading Room is (202) 566–1744, and 

the telephone number for the EPA 

Docket Center is (202) 566–1742. 

Public Hearing: If 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 10:00 a.m. (Eastern Standard 

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

(Eastern Standard Time). There will be 

a lunch break from 12:00 p.m. to 1:00 

p.m. Please contact 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 

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Federal Register / Vol. 79, No. 235 / Monday, December 8, 2014 / Proposed Rules 72915 

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. The hearing 

will provide interested parties the 

opportunity to present data, views or 

arguments concerning the proposed 

action. The EPA will make every effort 

to accommodate all speakers who arrive 

and register. Because these hearing are 

being held at U.S. government facilities, 

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. 

Docket: The EPA has established a 

docket for this rulemaking under Docket 

ID No. EPA–HQ–OAR–2011–0797. All 

documents in the docket are listed in 

the www.regulations.gov index. 

Although listed in the index, some 

information is not publicly available, 

e.g., CBI or other information whose 

disclosure is restricted by statute. 

Certain other material, such as 

copyrighted material, will be publicly 

available only in hard copy. Publicly 

available docket materials are available 

either electronically in 

www.regulations.gov or in hard copy at 

the EPA Docket Center, EPA WJC West 

Building, Room 3334, 1301 Constitution 

Ave. NW., Washington, DC. The Public 

Reading Room is open from 8:30 a.m. to 

4:30 p.m., Monday through Friday, 

excluding legal holidays. The telephone 

number for the Public Reading Room is 

(202) 566–1744, and the telephone 

number for the Air Docket is (202) 566– 

1742. 

FOR FURTHER INFORMATION CONTACT: For 

questions about this proposed action, 

contact Mr. David Putney, Sector 

Policies and Programs Division (D243– 

02), Office of Air Quality Planning and 

Standards, Environmental Protection 

Agency, Research Triangle Park, NC 

27711; telephone (919) 541–2016; fax 

number: (919) 541–3207; and email 

address: putney.david@epa.gov. For 

specific information regarding the risk 

modeling methodology, contact Mr. Jim 

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 Mr. Patrick Yellin, Office of 

Enforcement and Compliance 

Assurance, U.S. Environmental 

Protection Agency, EPA WJC West 

Building, Mail Code 2227A, 1200 

Pennsylvania Avenue NW., Washington, 

DC 20460; telephone number: (202) 

564–2970 and email address: 

yellin.patrick@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: 

As arsenic 

ADAF age-dependent adjustment factor 

AEGL acute exposure guideline levels 

AERMOD air dispersion model used by the 

HEM–3 model 

ATSDR Agency for Toxic Substances and 

Disease Registry 

BLDS bag leak detection system 

BTF beyond-the-floor 

CAA Clean Air Act 

CalEPA California EPA 

CBI Confidential Business Information 

Cd cadmium 

CE Cost Effectiveness 

CFR Code of Federal Regulations 

COS carbonyl sulfide 

Cr chromium 

Cr+3 trivalent chromium 

Cr+6 hexavalent chromium 

CWPB1 center-worked prebake one 

CWPB2 center-worked prebake two 

CWPB3 center-worked prebake three 

D/Fs polychlorinated dibenzo-p-dioxins 

and polychlorinated dibenzofurans 

EF Emission Factors 

EJ environmental justice 

EPA Environmental Protection Agency 

ERPG Emergency Response Planning 

Guidelines 

ERT Electronic Reporting Tool 

FR Federal Register 

HAP hazardous air pollutants 

HEM–3 Human Exposure Model, Version 

1.1.0 

HF hydrogen fluoride 

Hg mercury 

HI Hazard Index 

HQ Hazard Quotient 

HSS horizontal stud Soderberg 

IRIS Integrated Risk Information System 

km kilometer 

LOAEL lowest-observed-adverse-effect level 

LOEL lowest-observed-effect level 

MACT maximum achievable control 

technology 

MCEM methylene chloride extractable 

matter 

mg/dscm milligrams per dry standard cubic 

meter 

mg/kg-day milligrams per kilogram-day 

mg/m3 milligrams per cubic meter 

MIR maximum individual risk 

Mn manganese 

MRL Minimal Risk Level 

NAAQS National Ambient Air Quality 

Standards 

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 

Ni nickel 

NOAEL no-observed-adverse-effect level 

NRC National Research Council 

NTTAA National Technology Transfer and 

Advancement Act 

OAQPS Office of Air Quality Planning and 

Standards 

OECA Office of Enforcement and 

Compliance Assurance 

OMB Office of Management and Budget 

PAH polycyclic aromatic hydrocarbons 

Pb lead 

PB–HAP hazardous air pollutants known to 

be persistent and bio-accumulative in the 

environment 

PCB polychlorinated biphenyls 

PEL probable effect level 

PM particulate matter 

POM polycyclic organic matter 

ppm parts per million 

RDL representative method detection level 

REL reference exposure level 

RFA Regulatory Flexibility Act 

RfC reference concentration 

RfD reference dose 

RTR residual risk and technology review 

SAB Science Advisory Board 

SBA Small Business Administration 

SSM startup, shutdown and malfunction 

SWPB side-worked prebake 

TF total fluorides 

TOSHI target organ-specific hazard index 

TPY tons per year 

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72916 Federal Register / Vol. 79, No. 235 / Monday, December 8, 2014 / Proposed Rules 

1U.S. EPA. Documentation for Developing the 

Initial Source Category List—Final Report, EPA/

OAQPS, EPA–450/3–91–030, July, 1992. 

TRIM.FaTE Total Risk Integrated 

Methodology.Fate, Transport, and 

Ecological Exposure model 

TTN echnology Transfer Network 

UF uncertainty factor 

mg/dscm micrograms per dry standard cubic 

meter 

mg/m3 micrograms per cubic meter 

UMRA Unfunded Mandates Reform Act 

UPL Upper Prediction Limit 

URE unit risk estimate 

VCS voluntary consensus standards 

VSS1 vertical stud Soderberg one 

VSS2 vertical stud Soderberg two 

Organization of this Document. The 

information in this preamble is 

organized as follows: 

I. General Information 

A. Does this action apply to me? 

B. Where can I get a copy of this document 

and other related information? 

C. What should I consider as I prepare my 

comments for the EPA? 

II. Background 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 Primary 

Aluminum Production source category 

risk and technology review? 

D. What data collection activities were 

conducted to support this action? 

III. Analytical Procedures 

A. For purposes of this supplemental 

proposal, how did we estimate the postMACT risks posed by the Primary 

Aluminum Production source category? 

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 Primary Aluminum 

Production Source Category 

A. What actions are we proposing pursuant 

to CAA sections 112(d)(2) and 112(d)(3)? 

B. What are the results of the risk 

assessment and analyses? 

C. What are our proposed decisions 

regarding risk acceptability, ample 

margin of safety and adverse 

environmental effects based on our 

revised analyses? 

D. What are the results and proposed 

decisions based on our technology 

review? 

E. What other actions are we proposing? 

F. What compliance dates are we 

proposing? 

V. Summary of 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? 

Table 1 of this preamble lists the 

industrial source category that is the 

subject of this supplemental proposal. 

Table 1 is not intended to be exhaustive 

but rather to provide a guide for readers 

regarding the entities that this proposed 

action is likely to affect. The proposed 

standards, once promulgated, will be 

directly applicable to the affected 

sources. Federal, state, local and tribal 

government entities would not be 

affected by this proposed action. As 

defined in the ‘‘Initial List of Categories 

of Sources Under Section 112(c)(1) of 

the Clean Air Act Amendments of 1990’’ 

(see 57 FR 31576, July 16, 1992), the 

‘‘Primary Aluminum Production’’ 

source category is any facility which 

produces primary aluminum by the 

electrolytic reduction process.1

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

Source category NESHAP NAICS code a

Primary Aluminum Production .................................................... Primary Aluminum Reduction Plants .......................................... 33131 

a 2012 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 proposed 

action at: http://www.epa.gov/ttn/atw/

alum/alumpg.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 RTR 

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 

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only to the following address: Roberto 

Morales, OAQPS Document Control 

Officer (C404–02), OAQPS, U.S. 

Environmental Protection Agency, 

Research Triangle Park, North Carolina 

27711, Attention Docket ID No. EPA– 

HQ–OAR–2011–0797. 

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 HAPs 

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 HAPs. For 

major sources, the technology-based 

NESHAP must reflect the maximum 

degree of emission reductions of HAPs 

achievable (after considering cost, 

energy requirements and non-air quality 

health and environmental impacts) and 

are commonly referred to as MACT 

standards. 

MACT standards must reflect the 

maximum degree of emissions reduction 

achievable through the application of 

measures, processes, methods, systems 

or techniques, including, but not limited 

to, measures that (1) reduce the volume 

of or eliminate pollutants through 

process changes, substitution of 

materials or other modifications; (2) 

enclose systems or processes to 

eliminate emissions; (3) capture or treat 

pollutants when released from a 

process, stack, storage or fugitive 

emissions point; (4) are design, 

equipment, work practice or operational 

standards (including requirements for 

operator training or certification); or (5) 

are a combination of the above. CAA 

section 112(d)(2)(A) through (E). The 

MACT standards may take the form of 

design, equipment, work practice or 

operational standards where the EPA 

first determines either that (1) a 

pollutant cannot be emitted through a 

conveyance designed and constructed to 

emit or capture the pollutant, or that 

any requirement for, or use of, such a 

conveyance would be inconsistent with 

law; or (2) the application of 

measurement methodology to a 

particular class of sources is not 

practicable due to technological and 

economic limitations. CAA section 

112(h)(1) and (2). 

The MACT ‘‘floor’’ is the minimum 

control level allowed for MACT 

standards promulgated under CAA 

section 112(d)(3) and may not be based 

on cost considerations. For new sources, 

the MACT floor cannot be less stringent 

than the emissions control that is 

achieved in practice by the 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 8 years. CAA 

section 112(d)(6). In conducting this 

review, the EPA is not required to 

recalculate the MACT floor. Natural 

Resources Defense Council (NRDC) v. 

EPA, 529 F.3d 1077, 1084 (D.C. Cir. 

2008). Association of Battery Recyclers, 

Inc. v. EPA, 716 F.3d 667, 672–73 (D.C. 

Cir. 2013). 

The second stage in standard-setting 

focuses on reducing any remaining (i.e., 

‘‘residual’’) risk according to CAA 

section 112(f). CAA section 112(f)(1) 

required that the EPA prepare a report 

to Congress discussing (among other 

things) methods of calculating the risks 

posed (or potentially posed) by sources 

after implementation of the MACT 

standards, the public health significance 

of those risks and the EPA’s 

recommendations as to legislation 

regarding such remaining risk. The EPA 

prepared and submitted the Residual 

Risk Report to Congress, EPA–453/R– 

99–001 (Risk Report) in March 1999. 

CAA section 112(f)(2) then provides that 

if Congress does not act on any 

recommendation in the Risk Report, the 

EPA must analyze and address residual 

risk for each category or subcategory of 

sources 8 years after promulgation of 

such standards pursuant to CAA section 

112(d). 

Section 112(f)(2) of the CAA requires 

the EPA to determine for source 

categories subject to MACT standards 

whether the emission standards provide 

an ample margin of safety to protect 

public health. Section 112(f)(2)(B) of the 

CAA expressly preserves the EPA’s use 

of the two-step process for developing 

standards to address any residual risk 

and the agency’s interpretation of 

‘‘ample margin of safety’’ developed in 

the National Emissions Standards for 

Hazardous Air Pollutants: Benzene 

Emissions from Maleic Anhydride 

Plants, Ethylbenzene/Styrene Plants, 

Benzene Storage Vessels, Benzene 

Equipment Leaks, and Coke By-Product 

Recovery Plants (Benzene NESHAP) (54 

FR 38044, September 14, 1989). The 

EPA notified Congress in the Risk 

Report that the agency intended to use 

the Benzene NESHAP approach in 

making CAA section 112(f) residual risk 

determinations (EPA–453/R–99–001, p. 

ES–11). The EPA subsequently adopted 

this approach in its residual risk 

determinations and in a challenge to the 

risk review for the Synthetic Organic 

Chemical Manufacturing source 

category, the United States Court of 

Appeals for the District of Columbia 

Circuit upheld as reasonable the EPA’s 

interpretation that CAA section 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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2 ‘‘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 38045, September 14, 1989. We 

discussed the maximum individual 

lifetime cancer risk (or maximum 

individual risk (MIR)) as being ‘‘the 

estimated risk that a person living near 

a plant would have if he or she were 

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 riskbased 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 CAA section 112(f)(2) 

‘‘incorporates the EPA’s interpretation 

of the Clean Air Act from the Benzene 

Standard.’’ The court further held that 

Congress’ incorporation of the Benzene 

standard applies equally to carcinogens 

and non-carcinogens. 529 F.3d at 1081– 

82. Accordingly, we also consider 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 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,2 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 38044–38045, September 14, 1989, 

we stated as an overall objective: 

In protecting public health with an ample 

margin of safety under section 112, EPA 

strives to provide maximum feasible 

protection against risks to health from 

hazardous air pollutants by (1) protecting the 

greatest number of persons possible to an 

individual lifetime risk level no higher than 

approximately 1-in-1 million and (2) limiting 

to no higher than approximately 1-in-10 

thousand [i.e., 100-in-1 million] the 

estimated risk that a person living near a 

plant would have if he or she were exposed 

to the maximum pollutant concentrations for 

70 years. 

The agency further stated that ‘‘[t]he 

EPA also considers incidence (the 

number of persons estimated to suffer 

cancer or other serious health effects as 

a result of exposure to a pollutant) to be 

an important measure of the health risk 

to the exposed population. Incidence 

measures the extent of health risks to 

the exposed population as a whole, by 

providing an estimate of the occurrence 

of cancer or other serious health effects 

in the exposed population.’’ Id. at 

38045. 

In the ample margin of safety decision 

process, the agency again considers all 

of the health risks and other health 

information considered in the first step, 

including the incremental risk reduction 

associated with standards more 

stringent than the MACT standard or a 

more stringent standard that the EPA 

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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 NESHAP for Primary Aluminum 

Reduction Plants were promulgated on 

October 7, 1997 (62 FR 52407), codified 

at 40 CFR part 63, subpart LL (referred 

to as subpart LL or MACT rule in the 

remainder of this preamble), and 

amended on November 2, 2005 (70 FR 

66285). The MACT rule is applicable to 

facilities with affected sources 

associated with the production of 

aluminum by electrolytic reduction. 

These facilities are described in the 

following paragraph and collectively 

comprise what is commonly known as 

the Primary Aluminum Production 

source category. 

Aluminum is produced from refined 

bauxite ore (also known as alumina), 

using an electrolytic reduction process 

in a series of cells called a ‘‘potline.’’ 

The raw materials include alumina, 

petroleum coke, pitch and fluoride salts. 

According to information available on 

the Web site of The Aluminum 

Association, Inc. (http://

www.aluminum.org), approximately 40 

percent of the aluminum produced in 

the U.S. comes from primary aluminum 

facilities. The two main potline types 

are prebake (a newer, higher efficiency, 

lower-emitting technology) and 

Soderberg (an older, lower efficiency, 

higher-emitting technology). There are 

currently 13 facilities located in the 

United States that are subject to the 

requirements of this NESHAP: 12 

primary aluminum production plants 

and one carbon-only prebake anode 

production facility. These 12 primary 

aluminum production plants have 

approximately 45 potlines that produce 

aluminum. Ten primary aluminum 

production plants have a paste 

production operation, and 10 of the 12 

primary aluminum production plants 

have anode bake furnaces. Eleven of the 

12 primary aluminum facilities use 

prebake potlines; the other plant uses 

Soderberg potlines. Due to a decrease in 

demand for aluminum, four of the 

facilities are currently idle, including 

the Soderberg facility. The major HAPs 

emitted by these facilities are carbonyl 

sulfide (COS), hydrogen fluoride (HF), 

particulate HAP metals and polycyclic 

organic matter (POM), specifically 

polycyclic aromatic hydrocarbons 

(PAH). 

The standards promulgated in 1997 

and 2005 apply to emissions of HF, 

measured using total fluorides (TF) as a 

surrogate, from all potlines and anode 

bake furnaces and POM (as measured by 

methylene chloride extractables) from 

Soderberg potlines, anode bake 

furnaces, paste production plants and 

pitch storage tanks associated with 

primary aluminum production. Affected 

sources under the rules are each potline, 

each anode bake furnace (except for one 

that is located at a facility that only 

produces anodes for use off-site), each 

paste production plant and each new 

pitch storage tank. 

The NESHAP designated seven 

subcategories of existing potlines based 

primarily on differences in the process 

operation and configuration. The 

control of primary emissions from the 

reduction process is typically achieved 

by a dry alumina scrubber (with a 

baghouse to collect the alumina and 

other particulate matter (PM)). The 

control technology typically used for 

anode bake furnaces is a dry alumina 

scrubber. A capture system vented to a 

dry coke scrubber is used for control of 

paste production plants. See Tables 2 

and 3 for the applicable emission limits 

established under the 1997 NESHAP 

and the 2005 Amendments. 

TABLE 2—SUMMARY OF CURRENT MACT EMISSION LIMITS FOR EXISTING SOURCES UNDER THE 1997 NESHAP, AND

THE 2005 AMENDMENTS

Source Pollutant Emission limit 

Potlines 1

CWPB1 potlines ................................. TF ................. 0.95 kg/Mg (1.9 lb/ton) of aluminum produced. 

CWPB2 potlines ................................. TF ................. 1.5 kg/Mg (3.0 lb/ton) of aluminum produced. 

CWPB3 potlines ................................. TF ................. 1.25 kg/Mg (2.5 lb/ton) of aluminum produced. 

SWPB potlines ................................... TF ................. 0.8 kg/Mg (1.6 lb/ton) of aluminum produced. 

VSS1 potlines ..................................... TF ................. 1.1 kg/Mg (2.2 lb/ton) of aluminum produced. 

POM ............. 1.2 kg/Mg (2.4 lb/ton) of aluminum produced. 

VSS2 potlines ..................................... TF ................. 1.35 kg/Mg (2.7 lb/ton) of aluminum produced. 

POM ............. 2.85 kg/Mg (5.7 lb/ton) of aluminum produced. 

HSS potlines ...................................... TF ................. 1.35 kg/Mg (2.7 lb/ton) of aluminum produced. 

POM ............. 2.35 kg/Mg (4.7 lb/ton) of aluminum produced. 

Paste Production ....................................... POM ............. Install, operate and maintain equipment for capture of emissions and vent to a dry 

coke scrubber. 

Anode Bake Furnace (collocated with a 

primary aluminum plant).

TF ................. 0.10 kg/Mg (0.20 lb/ton) of green anode. 

POM ............. 0.09 kg/Mg (0.18 lb/ton) of green anode. 

1CWPB1 = Center-worked prebake potline with the most modern reduction cells; includes all center-worked prebake potlines not specifically 

identified as CWPB2 or CWPB3. 

CWPB2 = Center-worked prebake potlines located at Alcoa in Rockdale, Texas; Kaiser Aluminum in Mead, Washington; Ormet Corporation in 

Hannibal, Ohio; Ravenswood Aluminum in Ravenswood, West Virginia; Reynolds Metals in Troutdale, Oregon; and Vanalco Aluminum in Vancouver, Washington. 

CWPB3 = Center-worked prebake potline that produces very high purity aluminum, has wet scrubbers as the primary control system and is located at the Century Aluminum primary aluminum plant in Kentucky. 

HSS = Horizontal stud Soderberg potline (no facilities remain in the U.S.). 

SWPB = Side-worked prebake potline. 

VSS1 = Vertical stud Soderberg potline (no facilities remain in the U.S.). 

VSS2 = Vertical stud Soderberg potlines (located at an idle facility known as Columbia Falls Aluminum in Columbia Falls, Montana). 

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TABLE 3—SUMMARY OF CURRENT MACT EMISSION LIMITS FOR NEW SOURCES UNDER THE 1997 NESHAP, AND THE

2005 AMENDMENTS

Source Pollutant Emission limit 

All Potlines ................................................. TF ................. 0.6 kg/Mg (1.2 lb/ton) of aluminum produced. 

VSS1, VSS2 and HSS potlines ................. POM ............. 0.32 kg/Mg (0.63 lb/ton) of aluminum produced. 

Paste Production ....................................... POM ............. Install, operate and maintain equipment for capture of emissions and vent to a dry 

coke scrubber. 

Anode Bake Furnace (collocated with a 

primary aluminum plant).

TF ................. 0.01 kg/Mg (0.020 lb/ton) of green anode. 

POM ............. 0.025 kg/Mg (0.05 lb/ton) of green anode. 

Pitch storage tanks .................................... POM ............. Emission control system designed and operated to reduce inlet POM emissions by 

95 percent or greater. 

The 1997 NESHAP for primary 

aluminum reduction plants incorporates 

new source performance standards for 

potroom groups. These emission limits 

are listed in Table 3. The limits for new 

Soderberg facilities apply to any 

Soderberg facility that adds a new 

potroom group to an existing potline or 

is associated with a potroom group that 

meets the definition of a modified or 

reconstructed potroom group. Since 

these POM limits are very stringent, 

they effectively preclude the operation 

of any new Soderberg potlines. We 

expect any new potline would need to 

be a prebake potline to comply with the 

new source limits in the NESHAP. 

Compliance with the emission limits 

in the current rule is demonstrated by 

performance testing which can be 

addressed individually for each affected 

source or according to emissions 

averaging provisions. Monitoring 

requirements include monthly 

measurements of TF secondary 

emissions, quarterly measurement of 

POM secondary emissions and annual 

measurement of primary emissions, 

continuous parametric monitoring for 

each emission control device, a 

monitoring device to track daily weight 

of aluminum produced and daily 

inspection for visible emissions. 

Recordkeeping for the rule is consistent 

with the General Provisions 

requirements with the addition of 

recordkeeping for daily production of 

aluminum, records supporting 

emissions averaging and records 

documenting the portion of TF 

measured as PM or gaseous form. 

C. What is the history of the Primary 

Aluminum Production source category 

risk and technology review? 

Pursuant to section 112(f)(2) of the 

CAA, in 2011 we conducted an initial 

evaluation of the residual risk 

associated with the NESHAP for 

Primary Aluminum Reduction Plants. 

At that time, we also conducted an 

initial technology review pursuant to 

section 112(d)(6) of the CAA. Finally, 

we also reviewed the 2005 MACT rule 

to determine whether other 

amendments were appropriate. Based 

on the results of that initial RTR, and 

the MACT rule review, we proposed 

amendments to the NESHAP (also 

known as subpart LL) on December 6, 

2011 (76 FR 76260) (referred to as the 

2011 proposal in the remainder of this 

FR document). The proposed 

amendments in the 2011 proposal 

which we are revisiting in today’s 

supplemental proposal include the 

following: 

• Proposed emission limits for POM 

from prebake potlines; 

• Amendments to the monitoring, 

notification, recordkeeping and testing 

requirements; and 

• Proposed provisions establishing an 

affirmative defense to civil penalties for 

violations caused by malfunctions. 

As explained below, we are also 

proposing provisions which have no 

analogue in the 2011 proposal. 

The comment period for the 

December 2011 proposal opened on 

December 6, 2011, and ended on 

February 1, 2012. We received 

significant comments from industry 

representatives, environmental 

organizations and state regulatory 

agencies. After reviewing the comments, 

and after consideration of additional 

data and information received since the 

2011 proposal, we determined it is 

appropriate to revise some of our 

analyses and to publish a supplemental 

proposal. After collecting and reviewing 

additional data, we are proposing 

technology-based emission limits 

pursuant to CAA sections 112(d)(2) and 

(3) for PM, as a surrogate for particulate 

HAP metals, for new and existing 

potlines, anode bake furnaces and paste 

plants. We are also proposing revised 

technology-based emissions limits for 

POM emissions from prebake potlines 

and amendments to the monitoring, 

notification, recordkeeping and testing 

requirements to implement these 

emission limits. Pursuant to CAA 

section 112(f)(2), we are also proposing 

risk-based emission standards for POM, 

nickel (Ni) and arsenic (As) emissions 

from potlines in the VSS2 subcategory 

and proposing testing and monitoring 

requirements to demonstrate 

compliance with the standards for Ni 

and As. We are also proposing revisions 

to the testing and compliance 

requirements for COS emissions. 

In addition, we are withdrawing our 

2011 proposal to include an affirmative 

defense in this rule in light of a recent 

court decision vacating an affirmative 

defense in one of the EPA’s CAA section 

112(d) regulations. NRDC v. EPA, 749 F. 

3d 1055 (D.C. Cir. 2014) (vacating 

affirmative defense provisions in CAA 

section 112(d) rule establishing 

emission standards for Portland cement 

kilns). 

Today’s supplemental proposed 

rulemaking will allow the public an 

opportunity to review and comment on 

the revised analyses and revised 

proposed amendments described above. 

However, we also proposed other 

requirements in the 2011 proposal 

(listed below) for which we have made 

no revisions to the analyses, are not 

proposing any changes and are not 

reopening for public comment. These 

are: 

• POM standards for existing pitch 

storage tanks and related monitoring, 

reporting and testing requirements; 

• Emissions limits for COS from 

potlines; 

• Elimination of startup, shutdown 

and malfunction (SSM) exemptions; and 

• Electronic reporting. 

The comment period for the 

December 2011 proposal opened on 

December 6, 2011, and ended on 

February 1, 2012. We will address the 

comments we received during the 

public comment period for the 2011 

proposal at the time we publish final 

RTR amendments for the Primary 

Aluminum Production source category 

based on the 2011 proposal and today’s 

supplemental proposal. 

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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. 

D. What data collection activities were 

conducted to support this action? 

The 2011 risk assessment was based 

on estimates of PAH emissions derived 

from test measurements conducted in 

the 1990’s on facilities that may not 

have been representative of current 

operating practices and using test 

methods that were inferior to those 

currently available. In addition, data 

available to estimate emissions of HAP 

metals from potlines were very limited, 

and no data were available to estimate 

HAP metals emissions from anode bake 

furnaces and paste plants. Furthermore, 

no data were available to estimate 

dioxin/furan (D/F) and polychlorinated 

biphenyl (PCB) emissions from potlines, 

anode bake furnaces and paste plants. 

The proposed emission limits for 

POM from prebake potlines included in 

the 2011 proposal were based on 

extremely limited data. Also lacking 

were reliable data on which to base 

MACT standards for PM (as a surrogate 

for HAP metals) emissions from 

potlines, anode bake furnaces and paste 

plants. 

Therefore, in March 2013 we sent an 

information request to the primary 

aluminum companies pursuant to 

section 114 of the CAA to gather 

additional relevant emissions test data. 

In response to this request, selected 

facilities provided the following data: 

• Additional emission test data for 

POM emissions from prebake potlines; 

• Additional emission test data for 

PM emissions from prebake potlines, 

Soderberg potlines (which have 

subsequently shut down), anode bake 

furnaces and paste plants; 

• Additional emission test data for 

speciated PAH, speciated HAP metals, 

speciated PCBs and speciated 

polychlorinated dibenzo-p-dioxins and 

polychlorinated dibenzofurans from 

potlines, anode bake furnaces and paste 

plants. 

III. Analytical Procedures 

A. For purposes of this supplemental 

proposal, how did we estimate the postMACT risks posed by the Primary 

Aluminum Production source category? 

The EPA conducted a risk assessment 

that provides estimates of the MIR 

posed by the HAP emissions from each 

source in the source category, the 

hazard index (HI) for chronic exposures 

to HAP with the potential to cause 

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 eight 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: Residual Risk 

Assessment for the Primary Aluminum 

Production Source Category in Support 

of the 2014 Supplemental Proposal. The 

methods used to assess risks (as 

described in the eight 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? 

Using the test reports from the 2013 

information request we calculated 

annual emission rates of PAHs, D/Fs, 

PCBs and HAP metals from primary and 

secondary potline exhausts, anode bake 

furnace exhausts and paste plant 

exhausts. Where no test data were 

available we calculated and applied 

emission factors (EF) for these 

pollutants and emission points based on 

average emission rates from similarly 

operated sources to estimate emissions. 

However, it is important to note that 

only two facilities tested for D/F and 

PCBs. Furthermore, many of the test 

results for D/Fs and PCBs were below 

detection limits. More than half of the 

mercury (Hg) emissions tests results 

were also below detection limit. 

Therefore, there are greater uncertainties 

regarding D/F, PCB and Hg emissions 

compared to the other HAP. To estimate 

emissions in cases where some, but not 

all, data were below the detection limit, 

we assumed the undetected emissions 

were equal to one-half the detection 

limit, which is the established approach 

for dealing with non-detects in the 

EPA’s RTR program when developing 

emissions estimates for input to the risk 

assessments. Subsequently, we 

developed EF based on these limited 

data to estimate emissions at the other 

facilities. We believe the emissions 

estimates for D/F and PCBs are quite 

conservative (i.e., more likely to be 

overestimated rather than 

underestimated) because we assumed 

undetected emissions were equal to one 

half the detection limit. We note that 

EPA may, but is not obligated to amend 

MACT standards. In the case of D/F, Hg 

and PCB, where many of the emissions 

tests were below detection limit, and 

given the uncertainties and limitations 

of the data (for example, we have test 

data for D/F and PCBs for only one of 

the 11 prebake facilities), the EPA is 

choosing not to propose standards for 

these HAP at this time. 

We also obtained test data from recent 

compliance tests for TF and estimated 

HF emissions from primary and 

secondary potline exhausts and anode 

bake furnace exhausts. We estimated 

COS emissions as described in the 2011 

risk assessment. We did not receive any 

additional test data for COS. Thus, the 

emissions estimates for COS have not 

changed since the 2011 proposal. As 

noted above, we are not accepting 

further comment on either this analysis 

or the proposed emission limit for COS. 

We also verified information 

regarding emissions release 

characteristics such as stack heights, 

stack gas exit velocities, stack 

temperatures and source locations. In 

addition to the quality assurance (QA) 

of the source data for the facilities 

contained in the dataset, we also 

checked the coordinates of every 

emission source in the dataset using 

tools such as Google Earth. Where 

coordinates used in the 2011 risk 

assessment were found to be incorrect, 

we identified and corrected them. We 

also performed a QA assessment of the 

emissions data and release 

characteristics to ensure the data were 

reliable and that there were no outliers. 

The emissions data and the methods 

used to estimate emissions from all the 

various emissions sources are described 

in more detail in the technical 

document: Revised Draft Development 

of the RTR Emissions Dataset for the 

Primary Aluminum Production Source 

Category, which is available in the 

docket for this action (Docket ID No. 

EPA–HQ–OAR–2011–0797). 

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 current 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 

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72922 Federal Register / Vol. 79, No. 235 / Monday, December 8, 2014 / Proposed Rules 

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. 

7National Toxicology Program (NTP), 2011. 

Report on Carcinogens. 12th ed. Research Triangle 

Park, NC: US Department of Health and Human 

Services (DHHS), Public Health Service. Available 

online at http://ntp.niehs.nih.gov/ntp/roc/twelfth/

roc12.pdf. 

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 actions, we noted that assessing 

the risks at the MACT-allowable level is 

inherently reasonable since these risks 

reflect the maximum level facilities 

could emit and still comply with 

national emission standards. We also 

explained that it is reasonable to 

consider actual emissions, where such 

data are available, in both steps of the 

risk analysis, in accordance with the 

Benzene NESHAP approach. 

For this supplemental proposal, we 

evaluated allowable emissions based on 

responses to the information request. 

We estimated that allowable emissions 

for the currently regulated HAP (i.e., 

PAHs and HF) were generally about 1.5 

times higher than the actual emissions. 

Therefore, to calculate allowable 

emissions of PAHs and HF, we assumed 

that allowable emissions were 1.5 times 

the actual emissions for all facilities 

except for one idle Soderberg facility 

(Columbia Falls). For Columbia Falls, 

which has the highest potential for 

emissions of all the facilities, we 

evaluated site-specific data and 

estimated that allowable emissions for 

the regulated HAP (i.e., PAHs and HF) 

were about 1.9 times higher than 

estimated actual emissions when the 

plant is operating. Regarding 

unregulated HAP, the NESHAP 

currently includes no standards for 

COS, PCB, D/F and HAP metal 

emissions. Since there is no standard in 

place for these HAP and, therefore, no 

defined level of ‘‘MACT allowable’’ 

emissions levels, we assumed that 

allowable emissions for COS, PCB, D/F 

and HAP metal emissions were equal to 

estimated actual emissions. Further 

explanation is provided in the technical 

document: Revised Draft Development 

of the RTR Emissions Dataset for the 

Primary Aluminum Production Source 

Category, which is available in the 

docket (Docket ID No. EPA–HQ–OAR– 

2011–0797). 

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://www2.epa.gov/

fera/dose-response-assessmentassessing-health-risks-associatedexposure-hazardous-air-pollutants 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 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 doseresponse 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. 

In the case of Ni compounds, to 

provide a health-protective estimate of 

potential cancer risks, we used the IRIS 

URE value for Ni subsulfide in the 

assessment for the 2011 proposed rule 

for the Primary Aluminum Production 

source category. Based on past scientific 

and technical considerations, the 

determination of the percent of Ni 

subsulfide was considered a major 

factor for estimating the extent and 

magnitude of the risks of cancer due to 

Ni-containing emissions. Nickel 

speciation information for some of the 

largest Ni-emitting sources (including 

oil combustion, coal combustion and 

others) suggested that at least 35 percent 

of total Ni emissions may be soluble 

compounds and that the URE for the 

mixture of inhaled Ni compounds 

(based on Ni subsulfide, and 

representative of pure insoluble 

crystalline Ni) could be derived to 

reflect the assumption that 65 percent of 

the total mass of Ni may be 

carcinogenic. 

Based on consistent views of major 

scientific bodies (i.e., National 

Toxicology Program (NTP) in their 12th 

Report of the Carcinogens (ROC),7

International Agency for Research on 

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8 International Agency for Research on Cancer 

(IARC), 1990. IARC Monographs on the Evaluation 

of Carcinogenic Risks to Humans. Chromium, 

nickel, and welding. Vol. 49. Lyons, France: 

International Agency for Research on Cancer, World 

Health Organization Vol. 49:256. 

9World Health Organization (WHO, 1991) and 

the European Union’s Scientific Committee on 

Health and Environmental Risks (SCHER, 2006). 

10 Grimsrud TK and Andersen A. Evidence of 

Carcinogenicity in Humans of Water-soluble Nickel 

Salts. J Occup Med Toxicol 2010, 5:1–7. Available 

online at http://www.ossup-med.com/content/5/1/7. 

11Two UREs (other than the current IRIS values) 

have been derived for nickel compounds as a group: 

One developed by the California Department of 

Health Services (http://www.arb.ca.gov/toxics/id/

summary/nickel_tech_b.pdf) and the other by the 

Texas Commission on Environmental Quality 

(http://www.epa.gov/ttn/atw/nata1999/99pdfs/

healtheffectsinfo.pdf). 

12These 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. 

13U.S. EPA. Performing risk assessments that 

include carcinogens described in the Supplemental 

Guidance as having a mutagenic mode of action. 

Science Policy Council Cancer Guidelines 

Implementation Work Group Communication II: 

Memo from W.H. Farland, dated October 4, 2005. 

14See the Risk Assessment for Source Categories 

document available in the docket for a list of HAP 

with a mutagenic mode of action. 

15U.S. EPA. Supplemental Guidance for 

Assessing Early-Life Exposure to Carcinogens. EPA/ 

630/R–03/003F, 2005. http://www.epa.gov/ttn/atw/

childrens_supplement_final.pdf. 

16U.S. EPA. Science Policy Council Cancer 

Guidelines Implementation Workgroup 

Communication II: Memo from W.H. Farland, dated 

June 14, 2006. 

Cancer (IARC) 8 and other international 

agencies) 9 that consider all Ni 

compounds to be carcinogenic, we 

currently consider all Ni compounds to 

have the potential of being carcinogenic 

to humans. The 12th Report of the 

Carcinogens states that the ‘‘combined 

results of epidemiological studies, 

mechanistic studies, and carcinogenic 

studies in rodents support the concept 

that Ni compounds generate Ni ions in 

target cells at sites critical for 

carcinogenesis, thus allowing 

consideration and evaluation of these 

compounds as a single group.’’ 

Although the precise Ni compound (or 

compounds) responsible for the 

carcinogenic effects in humans is not 

always clear, studies indicate that Ni 

sulfate and the combinations of Ni 

sulfides and oxides encountered in the 

Ni refining industries cause cancer in 

humans (these studies are summarized 

in a review by Grimsrud et al., 2010 10). 

The major scientific bodies mentioned 

above have also recognized that there 

are differences in toxicity and/or 

carcinogenic potential across the 

different Ni compounds. 

In the inhalation risk assessment for 

this supplemental proposal, we chose to 

take a conservative approach: we 

considered all Ni compounds to be as 

carcinogenic as Ni subsulfide and 

applied the IRIS URE for Ni subsulfide 

without a factor to reflect the 

assumption that 100 percent of the total 

mass of Ni may be as carcinogenic as 

pure Ni subsulfide. However, given that 

there are two additional URE values 11

derived for exposure to mixtures of Ni 

compounds, as a group, that are 2–3 fold 

lower than the IRIS URE for Ni 

subsulfide, the EPA also considers it 

reasonable to use a value that is 50 

percent of the IRIS URE for Ni 

subsulfide for providing an estimate of 

the lower end of the plausible range of 

cancer potency values for different 

mixtures of Ni compounds. 

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 12) 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 (MRL) (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) 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 

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. 

POM, a carcinogenic HAP with a 

mutagenic mode of action, is emitted by 

the facilities in this source category.13

For this compound group,14 the EPA’s 

analysis applies the age-dependent 

adjustment factors (ADAF) described in 

the EPA’s Supplemental Guidance for 

Assessing Susceptibility from Early-Life 

Exposure to Carcinogens.15 This 

adjustment has the effect of increasing 

the estimated lifetime risks for POM by 

a factor of 1.6. In addition, although 

primary aluminum facilities reported 

most of their total POM emissions as 

individual compounds, the EPA 

expresses carcinogenic potency for 

compounds in this group in terms of 

benzo[a]pyrene equivalence, based on 

evidence that carcinogenic POM has the 

same mutagenic mechanism of action as 

benzo[a]pyrene. For this reason, the 

EPA’s Science Policy Council 16

recommends applying the Supplemental 

Guidance to all carcinogenic PAH for 

which risk estimates are based on 

relative potency. Accordingly, we have 

applied the ADAF to the benzo[a]pyrene 

equivalent portion of all POM mixtures. 

As mentioned above, in order to 

characterize non-cancer chronic effects, 

and in response to key 

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17The 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. 

18National Academy of Sciences (NAS), 2001. 

Standing Operating Procedures for Developing 

Acute Exposure Levels for Hazardous Chemicals, 

page 2. 

19ERP Committee Procedures and 

Responsibilities. November 1, 2006. American 

Industrial Hygiene Association. 

recommendations from the SAB, the 

EPA selects dose-response values that 

reflect the best available science for all 

HAP included in RTR risk 

assessments.17 More specifically, for a 

given HAP, the EPA examines the 

availability of inhalation reference 

values from the sources included in our 

tiered approach (e.g., IRIS first, ATSDR 

second, CalEPA third) and determines 

which inhalation reference value 

represents the best available science. 

Thus, as new inhalation reference 

values become available, the EPA will 

typically evaluate them and determine 

whether they should be given 

preference over those currently being 

used in RTR risk assessments. 

The EPA also evaluated screening 

estimates of acute exposures and risks 

for each of the HAP (for which 

appropriate acute dose-response values 

are available) 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 the mandate of 

section 112(f)(2) of the CAA, we use the 

point of highest off-site exposure to 

assess the potential risk to the 

maximally exposed individual. The 

acute HQ is the estimated acute 

exposure divided by the acute doseresponse value. In each case, the EPA 

calculated acute HQ values using best 

available, short-term dose-response 

values. These acute dose-response 

values, which are described below, 

include the acute REL, acute exposure 

guideline levels (AEGL) and emergency 

response planning guidelines (ERPG) for 

1-hour exposure durations. As 

discussed below, we used conservative 

assumptions for emissions rates, 

meteorology and exposure location. 

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. 

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),18 ‘‘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/

AIHAGuidelineFoundation/Emergency

ResponsePlanningGuidelines/

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.’’ 19 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 

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20See http://www.tceq.state.tx.us/compliance/

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

source of these data. 

21The 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. 

22U.S. EPA. (2009) Chapter 2.9 Chemical Specific 

Reference Values for Formaldehyde in Graphical 

Continued 

effects for these chemicals are not 

consistent with the AEGL–1/ERPG–1 

definitions; in these instances, we 

compare higher severity level AEGL–2 

or ERPG–2 values to our modeled 

exposure levels to screen for potential 

acute concerns. When AEGL–1/ERPG–1 

values are available, they are used in 

our acute risk assessments. 

Acute REL values for 1-hour exposure 

durations are typically lower than their 

corresponding AEGL–1 and ERPG–1 

values. Even though their definitions are 

slightly different, AEGL–1 values are 

often the same as the corresponding 

ERPG–1 values, and AEGL–2 values are 

often equal to ERPG–2 values. 

Maximum HQ values from our acute 

screening risk assessments typically 

result when basing them on the acute 

REL value for a particular pollutant. In 

cases where our maximum acute HQ 

value exceeds 1, we also report the HQ 

value based on the next highest acute 

dose-response value (usually the AEGL– 

1 and/or the ERPG–1 value). 

To develop screening estimates of 

acute exposures in the absence of hourly 

emissions data, generally, we first 

develop estimates of maximum hourly 

emissions rates by multiplying the 

average actual annual hourly emissions 

rates by a default factor to cover 

routinely variable emissions. We choose 

the factor to use partially based on 

process knowledge and engineering 

judgment reflecting, where appropriate, 

circumstances of the particular source 

category at issue. 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 9.20

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 the Primary Aluminum 

Production source category, information 

was available to determine processspecific factors. The processes in this 

source category are typically equipped 

with controls which will not allow 

startup of the emission source until the 

associated control device is operating 

and will automatically shut down the 

emission source if the associated 

controls malfunction. Further, some 

processes, for example, the potlines, 

operate continuously so there are no 

significant spikes in emissions. We, 

thus, believe emissions from the 

potlines are relatively consistent over 

time with minimal fluctuation. 

However, we realize that emissions vary 

over time. Furthermore, as described 

above, we estimate the maximum 

allowable emissions for this source 

category are about 1.5 times higher than 

the average long-term actual emissions 

for these sources. Therefore, we assume 

that hourly emissions rates from 

potlines could occasionally increase by 

a factor of up to 1.5 times the average 

hourly emissions, which, for the reasons 

stated above, we believe is a valid 

multiplier to estimate maximum acute 

emissions from potlines. Other 

processes, for example paste production 

and anode baking, may have specific 

cycles, with peak emissions occurring 

for a part of that cycle. We assume these 

peak emissions could be as high as 2 

times the average emissions for paste 

plants and bake furnaces. As discussed 

in sections II.D and III.A.1 of this 

preamble, above, we collected data 

regarding the emissions from these 

processes. Those emissions data 

represent emissions during periods of 

normal operations (as opposed to during 

periods of peak emissions). 

Therefore, based on the modes of 

operation and other factors described 

above, we applied an acute emissions 

multiplier of 1.5 to all potline emissions 

for input to the acute risk assessment, 

and for paste production and anode 

baking we applied an acute emissions 

multiplier of 2. We regard these factors 

as conservative (i.e., they are designed 

not to underestimate variability). Even 

with data available to develop processspecific factors, our assessment of acute 

risk reflects conservative assumptions, 

in particular in its assumptions that 

every potline operates at the same hour 

and that every potline has emissions 1.5 

times higher than the average at the 

same hour, that this is the same hour as 

the worst-case dispersion conditions, 

and that a person is at the location of 

maximum concentration during that 

hour. This results in a conservative 

exposure scenario. 

As part of our acute risk assessment 

process, for cases where acute HQ 

values from the screening step were less 

than or equal to 1 for modeled HAPs 

(even under the conservative 

assumptions of the screening analysis), 

acute impacts were deemed negligible 

and no further analysis was performed 

for these HAPs. In cases where an acute 

HQ from the screening step was greater 

than 1, for some modeled HAPs 

additional site-specific data were 

considered to develop a more refined 

estimate of the potential for acute 

impacts of concern. These refinements 

are discussed more fully in the Residual 

Risk Assessment for the Primary 

Aluminum Production Source Category 

in Support of the 2014 Supplemental 

Proposal, which is available in the 

docket for this action (Docket ID No. 

EPA–HQ–OAR–2011–0797). 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 noted above, the agency may 

choose to refine the acute screen by also 

assessing the exposure that may occur at 

a centroid of census block. For this 

source category we first used 

conservative assumptions for emissions 

rates, meteorology and exposure 

location for our acute analysis. We then 

refined the acute assessment by also 

estimating the HQ for As at centroids of 

census blocks. 

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,21 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 22 for HAP have 

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72926 Federal Register / Vol. 79, No. 235 / Monday, December 8, 2014 / Proposed Rules 

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. 

23 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 the primary 

lead NAAQS reflects an adequate margin of safety. 

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 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). 

For the Primary Aluminum 

Production source category, we 

identified emissions of cadmium (Cd) 

compounds, D/F, POM, divalent Hg 

compounds and HF. However, as we 

explained in section III.A.1 of this 

preamble, many of the emissions tests 

for mercury and D/F were below 

detection limit or detection limit 

limited. Nevertheless, we estimated 

emissions of these HAP based on the 

conservative assumption that 

undetected emissions were equal to one 

half the detection limit. Therefore, we 

consider the estimates for D/F and Hg to 

be conservative (i.e., more likely to be 

overestimated rather than 

underestimated). 

Because one or more of the PB–HAP 

are emitted by at least one facility in the 

Primary Aluminum Production source 

category, we proceeded to the next step 

of the evaluation. In this step, we 

determined whether the facility-specific 

emissions rates of the emitted PB–HAP 

were large enough to create the potential 

for significant non-inhalation human 

health risks under reasonable worst-case 

conditions. To facilitate this step, we 

developed emissions rate screening 

levels for several PB–HAP using a 

hypothetical upper-end screening 

exposure scenario developed for use in 

conjunction with the EPA’s Total Risk 

Integrated Methodology.Fate, Transport, 

and Ecological Exposure (TRIM.FaTE) 

model. The PB–HAP with emissions 

rate screening levels are: Cd, lead, D/F, 

Hg compounds and POM. We 

conducted a sensitivity analysis on the 

screening scenario to ensure that its key 

design parameters would represent the 

upper end of the range of possible 

values, such that it would represent a 

conservative, but not impossible 

scenario. The facility-specific emissions 

rates of these PB–HAP were compared 

to the emission rate screening levels for 

these PB–HAP to assess the potential for 

significant human health risks via noninhalation pathways. We call this 

application of the TRIM.FaTE model the 

Tier 1 TRIM-screen or Tier 1 screen. 

For the purpose of developing 

emissions rates for our Tier 1 TRIMscreen, we derived emission levels for 

these PB–HAP (other than lead (Pb) 

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., Cd compounds and Hg 

compounds), the maximum HQ would 

be 1. If the emissions rate of any PB– 

HAP included in the Tier 1 screen 

exceeds the Tier 1 screening emissions 

rate for any facility, we conduct a 

second screen, which we call the Tier 2 

TRIM-screen or Tier 2 screen. 

In the Tier 2 screen, the location of 

each facility that exceeded the Tier 1 

emission rate is used to refine the 

assumptions associated with the 

environmental scenario while 

maintaining the exposure scenario 

assumptions. A key assumption that is 

part of the Tier 1 screen is that a lake 

is located near the facility; we confirm 

the existence of lakes near the facility as 

part of the Tier 2 screen. We then adjust 

the risk-based Tier 1 screening level for 

each PB–HAP for each facility based on 

an understanding of how exposure 

concentrations estimated for the 

screening 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. When facilities exceed the Tier 2 

screening levels, it does not mean that 

multipathway impacts are significant, 

only that we cannot rule out that 

possibility based on the results of the 

screen. 

If the PB–HAP emissions for a facility 

exceed the Tier 2 screening emissions 

rate, and data are available, we may 

decide to conduct a more refined Tier 3 

multipathway assessment. There are 

several analyses that can be included in 

a Tier 3 screen depending upon the 

extent of refinement warranted, 

including validating that the lake is 

fishable and considering plume-rise to 

estimate emissions lost above the 

mixing layer. If the Tier 3 screen is 

exceeded, the EPA may further refine 

the assessment. For this source category, 

we conducted 3 Tier 3 screening 

assessments at Alcoa (Ferndale, WA), 

Alumax (Goose Creek, SC) and Reynolds 

Metals (Massena, NY). The Reynolds 

Metals facility is a Soderberg facility 

which was operating at the time we sent 

out the information request and when 

we collected the emissions data and 

initiated the modeling assessment. 

However, recently this facility 

permanently shut down all their 

Soderberg potline operations. It is our 

understanding that this facility will 

either convert to a prebake facility or 

remain permanently shut down. A 

detailed discussion of the approach for 

this multipathway risk assessment can 

be found in Appendix 9 (Technical 

Support Document: Human Health 

Multipathway Residual Risk Screening 

Assessment for the Primary Aluminum 

Production Source Category) of the risk 

assessment document. 

In evaluating the potential 

multipathway risk from emissions of Pb 

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 Pb.23

Values below the level of the primary 

(health-based) Pb 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 

Primary Aluminum Production Source 

Category in Support of the 2014 

Supplemental Proposal, which is 

available in the docket for this action 

(Docket ID No. EPA–HQ–OAR–2011– 

0797). 

5. How did we assess risks considering 

the revised emissions control options? 

In addition to assessing baseline 

inhalation risks and potential 

multipathway risks, we also estimated 

risks considering the emission 

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24The 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.’’ 

reductions that would be achieved by 

the control options under consideration 

in this supplemental proposal (i.e., 

emission reductions reflecting the 

proposed standards reflecting MACT). 

In these cases, the expected emission 

reductions were applied to the specific 

HAP and emission points in the RTR 

emissions dataset to develop 

corresponding estimates of risk that 

would exist after implementation of the 

proposed amendments in today’s action. 

6. 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 Cd, D/F, POM, Hg (both 

inorganic Hg and methylmercury) and 

Pb compounds. The two acid gases are 

hydrogen chloride (HCl) and HF. We 

have no data indicating primary 

aluminum plants emit HCl. Therefore, 

our analysis for this source category 

does not reflect HCl emissions. The 

rationale for including the remaining six 

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). 

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 

Cd compounds, D/F, POM and Hg in 

soil, sediment and water. For Pb 

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 Pb compounds, we compare 

the estimated HEM–3 modeled 

exposures from the source category 

emissions of Pb with the level of the 

secondary NAAQS for Pb.24 We 

consider values below the level of the 

secondary Pb NAAQS as unlikely to 

cause adverse environmental effects. 

Due to its well-documented potential 

to cause direct damage to terrestrial 

plants, we include the acid gas HF 

emitted by primary aluminum sources, 

in the environmental screening analysis. 

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 

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 Pb 

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 Pb 

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 Cd compounds, D/F, POM and 

Hg, we identified the available 

ecological benchmarks for each 

assessment endpoint. An ecological 

benchmark represents a concentration of 

HAP (e.g., 0.77 ug 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 

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• 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 chronic benchmarks). For 

HCl, the EPA identified chronic 

benchmark concentrations. We note that 

the benchmark for chronic HCl exposure 

to plants is greater than the reference 

concentration for chronic inhalation 

exposure for human health. This means 

that where the EPA includes regulatory 

requirements to prevent an exceedance 

of the reference concentration for 

human health, additional analyses for 

adverse environmental effects of HCl 

would not be necessary. 

For HF, the EPA identified chronic 

benchmark concentrations for plants 

and evaluated chronic exposures to 

plants in the screening analysis. High 

concentrations of HF in the air have also 

been linked to fluorosis in livestock. 

However, the HF concentrations at 

which fluorosis in livestock occur are 

higher than those at which plant 

damage begins. Therefore, the 

benchmarks for plants are protective of 

both plants and livestock. 

e. Screening Methodology 

For the environmental risk screening 

analysis, the EPA first determined 

whether any facilities in the Primary 

Aluminum Production source category 

emitted any of the seven environmental 

HAP. For the Primary Aluminum 

Production source category, we 

identified emissions of five of the PB– 

HAP (Cd, Hg, Pb, D/F and POM) and 

one acid gas (HF). 

Because one or more of the seven 

environmental HAP evaluated are 

emitted by the facilities in the source 

category, we proceeded to the second 

step of the evaluation. 

f. PB–HAP Methodology 

For Cd, Hg, POM and D/F, the 

environmental screening analysis 

consists of two tiers, while Pb 

compounds are analyzed differently as 

discussed earlier. However, as we 

explained in section III.A.1 above, there 

are greater uncertainties in the 

emissions estimates for Hg or D/F 

because of the limitations in the 

available data and because a large 

portion of emissions tests results were 

below the detection limit for those HAP. 

Nevertheless, to be conservative (i.e., 

more likely to overestimate risks rather 

than underestimate risks), we have 

included emissions estimates of Hg and 

D/F in the PB–HAP risk screen based on 

conservative assumptions (i.e., 

emissions of one half the detection limit 

were assumed for those tests where no 

pollutants were detected). 

In the first tier, we determined 

whether the maximum facility-specific 

emission rates of each of the emitted 

environmental HAP were large enough 

to create the potential for adverse 

environmental effects under reasonable 

worst-case environmental conditions. 

These are the same environmental 

conditions used in the human 

multipathway exposure and risk 

screening analysis. 

To facilitate this step, TRIM.FaTE was 

run for each PB–HAP under 

hypothetical environmental conditions 

designed to provide conservatively high 

HAP concentrations. The model was set 

to maximize runoff from terrestrial 

parcels into the modeled lake, which in 

turn, maximized the chemical 

concentrations in the water, the 

sediments and the fish. The resulting 

media concentrations were then used to 

back-calculate a screening level 

emission rate that corresponded to the 

relevant exposure benchmark 

concentration value for each assessment 

endpoint. To assess emissions from a 

facility, the reported emission rate for 

each PB–HAP was compared to the 

screening level emission rate for that 

PB–HAP for each assessment endpoint. 

If emissions from a facility do not 

exceed the Tier 1 screening level, the 

facility ‘‘passes’’ the screen, and, 

therefore, is not evaluated further under 

the screening approach. If emissions 

from a facility exceed the Tier 1 

screening level, we evaluate the facility 

further in Tier 2. 

In Tier 2 of the environmental 

screening analysis, the emission rate 

screening levels are adjusted to account 

for local meteorology and the actual 

location of lakes in the vicinity of 

facilities that did not pass the Tier 1 

screen. The modeling domain for each 

facility in the Tier 2 analysis consists of 

eight octants. Each octant contains 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 HF (we have no 

data regarding HCl emissions from 

primary aluminum facilities and, 

therefore, HCl was not analyzed). The 

environmental risk screening 

methodology for HF is a single-tier 

screen that compares the average off-site 

ambient air concentration over the 

modeling domain to ecological 

benchmarks for each of the acid gases. 

Because air concentrations are 

compared directly to the ecological 

benchmarks, emission-based screening 

levels are not calculated for HF as they 

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are in the ecological risk screening 

methodology for PB–HAPs. 

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 Primary Aluminum 

Production Source Category in Support 

of the 2014 Supplemental Proposal, 

which is available in the docket for this 

action (Docket ID No. EPA–HQ–OAR– 

2011–0797). 

7. 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. We analyzed risks 

due to the inhalation of HAP that are 

emitted ‘‘facility-wide’’ for the 

populations residing within 50 km of 

each facility, consistent with the 

methods used for the source category 

analysis described above. The Residual 

Risk Assessment for the Primary 

Aluminum Production Source Category 

in Support of the 2014 Supplemental 

Proposal, available through the docket 

for this action, provides the 

methodology and results of the facilitywide analyses, including all facilitywide risks. 

8. 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 

Revised Draft Development of the RTR 

Emissions Dataset for the Primary 

Aluminum Production Source Category, 

and the Residual Risk Assessment for 

the Primary Aluminum Production 

Source Category in Support of the 2014 

Supplemental Proposal, which is 

available in the docket for this action 

(Docket ID No. EPA–HQ–OAR–2011– 

0797). 

a. Uncertainties in the RTR Emissions 

Dataset 

Although the development of the RTR 

emissions dataset involved QA/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 for 

each emission process group and 

applied to the average annual hourly 

emission rates, which are intended to 

account for emission fluctuations due to 

normal facility operations. 

As described above and in the Revised 

Draft Development of the RTR 

Emissions Dataset for the Primary 

Aluminum Production Source Category, 

we gathered a substantial amount of 

emissions test data from currently 

operating facilities (plus test data from 

a then-operating, now closed Soderberg 

facility). Required testing under the 

CAA section 114 request included 

measurements of HAP metal emissions 

from primary and secondary potline 

exhausts at seven facilities, as well as 

measurements of HAP metal emissions 

from three anode bake furnace exhausts 

and three paste plant exhausts. We also 

received additional POM emissions data 

from eight facilities. Furthermore, we 

received speciated PAH, PCB and D/F 

emissions data from primary and 

secondary exhausts of two potlines (one 

Soderberg potline and one prebake 

potline), as well as exhausts from one 

anode bake furnace and one paste plant. 

We used these data to estimate 

emissions from emission points for 

which we had no emissions test data. 

Also, there is additional uncertainty 

concerning the estimated emissions of 

Hg and D/F since, as discussed in 

sections III.A.1 and IV.A of this 

preamble, a substantial portion of the 

emissions test results for those HAP 

were reported as below laboratory 

detection limits. Finally, we received 

hexavalent chromium (Cr+6) emissions 

stack test data from primary and 

secondary potline exhausts at two 

facilities and an anode bake furnace and 

a paste plant at one facility. We used the 

average results from these tests to 

apportion emissions of Cr+6 and 

trivalent chromium (Cr+3) for the 

remaining facilities that did not test. 

Therefore, there are some uncertainties 

regarding the split between Cr+6 and 

Cr+3 for these remaining facilities. 

Nevertheless, we believe the test data 

we used are representative. Thus, the 

uncertainties are not significant. 

Furthermore, since we used the average 

results of the available tests, the values 

we used as input for the risk assessment 

are equally likely to be overestimates or 

underestimates of the actual speciated 

emissions. 

b. Uncertainties in Dispersion Modeling 

We recognize there is uncertainty in 

ambient concentration estimates 

associated with any model, including 

the EPA’s recommended regulatory 

dispersion model, AERMOD. In using a 

model to estimate ambient pollutant 

concentrations, the user chooses certain 

options to apply. For RTR assessments, 

we select some model options that have 

the potential to overestimate ambient air 

concentrations (e.g., not including 

plume depletion or pollutant 

transformation). We select other model 

options that have the potential to 

underestimate ambient impacts (e.g., not 

including building downwash). Other 

options that we select have the potential 

to either under- or overestimate ambient 

levels (e.g., meteorology and receptor 

locations). On balance, considering the 

directional nature of the uncertainties 

commonly present in ambient 

concentrations estimated by dispersion 

models, the approach we apply in the 

RTR assessments should yield unbiased 

estimates of ambient HAP 

concentrations. 

c. Uncertainties in Inhalation Exposure 

The EPA did not include the effects 

of human mobility on exposures in the 

assessment. Specifically, short-term 

mobility and long-term mobility 

between census blocks in the modeling 

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25Short-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. 

26U.S. EPA. National-Scale Air Toxics 

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

2001; page 85.) 

27 IRIS glossary (http://ofmpub.epa.gov/sor_

internet/registry/termreg/searchandretrieve/

glossariesandkeywordlists/search.do?details=&

glossaryName=IRIS%20Glossary). 

domain were not considered.25 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.26

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(f) 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 the primary aluminum source 

category, these assumptions would tend 

to be conservative 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. 

For the primary aluminum source 

category, we refined the acute exposure 

assessment by estimating the HQ at a 

centroid of a census block. This reduces 

the uncertainty in the assessment 

because we are evaluating the potential 

for exposures to occur at locations 

where people could actually live, rather 

than at the point of maximum off-site 

concentration. 

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 Guidelines for 

Carcinogen Risk Assessment (EPA/630/ 

P–03/001B, March 2005); 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’’ 

(Guidelines for Carcinogen Risk 

Assessment, 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 

Primary Aluminum Production Source 

Category in Support of the November 

2014 Proposal, which is available in the 

docket for this action (Docket ID No. 

EPA–HQ–OAR–2011–0797). 

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).27 In some 

circumstances, the true risk could be as 

low as zero; however, in other 

circumstances the risk could be greater. 

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 

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28According 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. 

29 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. 

limitations for other uses (e.g., prioritysetting 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,28 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 doseresponse 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. 

e. Uncertainties in the Multipathway 

Assessment 

For each source category, we 

generally rely on site-specific levels of 

PB–HAP emissions to determine 

whether a refined assessment of the 

impacts from multipathway exposures 

is necessary. This determination is 

based on the results of a three-tiered 

screening analysis that relies on the 

outputs from models that estimate 

environmental pollutant concentrations 

and human exposures for four PB–HAP. 

Two important types of uncertainty 

associated with the use of these models 

in RTR risk assessments and inherent to 

any assessment that relies on 

environmental modeling are model 

uncertainty and input uncertainty.29

Model uncertainty concerns whether 

the selected models are appropriate for 

the assessment being conducted and 

whether they adequately represent the 

actual processes that might occur for 

that situation. An example of model 

uncertainty is the question of whether 

the model adequately describes the 

movement of a pollutant through the 

soil. This type of uncertainty is difficult 

to quantify. However, based on feedback 

received from previous EPA SAB 

reviews and other reviews, we are 

confident that the models used in the 

screen are appropriate and state-of-theart 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 

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30 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. 

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 EPA 

conducted a multipathway assessment 

based on these scenarios, 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 Tier 1 and Tier 2. 

For both Tiers 1 and 2 of the 

multipathway assessment, our approach 

to addressing model input uncertainty is 

generally cautious. We choose model 

inputs from the upper end of the range 

of possible values for the influential 

parameters used in the models, and we 

assume that the exposed individual 

exhibits ingestion behavior that would 

lead to a high total exposure. This 

approach reduces the likelihood of not 

identifying high risks for adverse 

impacts. 

Despite the uncertainties, when 

individual pollutants or facilities do 

screen out, we are confident that the 

potential for adverse multipathway 

impacts on human health is very low. 

On the other hand, when individual 

pollutants or facilities do not screen out, 

it does not mean that multipathway 

impacts are significant, only that we 

cannot rule out that possibility and that 

a refined multipathway analysis for the 

site might be necessary to obtain a more 

accurate risk characterization for the 

source category. For further information 

on uncertainties and the Tier 1 and 2 

screening methods, refer to the risk 

document Appendix 5, Technical 

Support Document for TRIM-Based 

Multipathway Tiered Screening 

Methodology for RTR. 

We completed a Tier 3 multipathway 

screen for this supplemental proposal. 

This assessment contains less 

uncertainty compared to the Tier 1 and 

Tier 2 screens. The Tier 3 screen 

improves the lake characterization used 

in the Tier 2 analysis and improves the 

screen by adjusting for emissions lost to 

the upper air sink through plume-rise 

calculations. 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 here. The Tier 3 multipathway 

screen and related uncertainties are 

described in detail in section 4 of the 

Residual Risk Assessment for the 

Primary Aluminum Production Source 

Category in Support of the 2014 

Supplemental Proposal, which is 

available in the docket for this action 

(Docket ID No. EPA–HQ–OAR–2011– 

0797). 

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.30

Model uncertainty concerns whether 

the selected models are appropriate for 

the assessment being conducted and 

whether they adequately represent the 

movement and accumulation of 

environmental HAP emissions in the 

environment. For example, does the 

model adequately describe the 

movement of a pollutant through the 

soil? This type of uncertainty is difficult 

to quantify. However, based on feedback 

received from previous EPA SAB 

reviews and other reviews, we are 

confident that the models used in the 

screen are appropriate and state-of-theart 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 Pb compounds, which 

were evaluated by comparison to the 

secondary Pb NAAQS) that were 

included in the environmental 

screening assessment and each of the 

media when comparing to ecological 

benchmarks. This is consistent with the 

conservative design of Tier 1 of the 

screen. In Tier 2 of the environmental 

screening analysis for PB–HAP, we 

refine the model inputs to account for 

meteorological patterns in the vicinity 

of the facility versus using upper-end 

national values, and we identify the 

locations of water bodies near the 

facility location. By refining the 

screening approach in Tier 2 to account 

for local geographical and 

meteorological data, we decrease the 

likelihood that concentrations in 

environmental media are overestimated, 

thereby increasing the usefulness of the 

screen. To better represent widespread 

impacts, the modeled soil 

concentrations are averaged in Tier 2 to 

obtain one average soil concentration 

value for each facility and for each PB– 

HAP. For PB–HAP concentrations in 

water, sediment and fish tissue, the 

highest value for each facility for each 

pollutant is used. 

For the environmental screening 

assessment for acid gases, we employ a 

single-tiered approach. We use the 

modeled air concentrations and 

compare those with ecological 

benchmarks. 

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31As noted above, we have no data regarding HCl 

emissions from primary aluminum plants so the 

EPA did not evaluate HCl in this screening 

assessment for this proposal. 

32Although defined as ‘‘maximum individual 

risk,’’ MIR refers only to cancer risk. MIR, one 

metric for assessing cancer risk, is the estimated 

risk were an individual exposed to the maximum 

level of a pollutant for a lifetime. 

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 Pb compounds, 

which were evaluated through a 

comparison to the NAAQS for Pb and its 

compounds), 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: Cd, D/F, POM, Hg 

(both inorganic Hg and methylmercury), 

Pb compounds, HCl 31 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 

document ‘‘Technical Support 

Document for TRIM-Based 

Multipathway Tiered Screening 

Methodology for RTR: Summary of 

Approach and Evaluation.’’ Also, see 

the Residual Risk Assessment for the 

Primary Aluminum Production Source 

Category in Support of the 2014 

Supplemental Proposal, available in the 

docket for this action (Docket ID No. 

EPA–HQ–OAR–2011–0797). 

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) 32 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 

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33The 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. 

presence of non-cancer health effects, and the 

uncertainties of the risk estimates. In this 

way, the effect on the most exposed 

individuals can be reviewed as well as the 

impact on the general public. These factors 

can then be weighed in each individual case. 

This approach complies with the Vinyl 

Chloride mandate that the Administrator 

ascertain an acceptable level of risk to the 

public by employing [her] expertise to assess 

available data. It also complies with the 

Congressional intent behind the CAA, which 

did not exclude the use of any particular 

measure of public health risk from the EPA’s 

consideration with respect to CAA section 

112 regulations, and thereby implicitly 

permits consideration of any and all 

measures of health risk which the 

Administrator, in [her] judgment, believes are 

appropriate to determining what will ‘protect 

the public health’.’’ 

See 54 FR at 38057, September 14, 1989. 

Thus, the level of the MIR is only one 

factor to be weighed in determining 

acceptability of risks. The Benzene 

NESHAP explained that ‘‘an MIR of 

approximately 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.’’ 33

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. 

As discussed in more detail below, 

based on the results of these risk 

analyses and evaluation of control 

options, we are proposing revised limits 

for emissions of POM from potlines, and 

first ever emissions limits for emissions 

of PM (as a surrogate for HAP metals) 

from potlines, anode bake furnaces and 

paste production plants and for 

emissions of Ni and As, from the VSS2 

potline subcategory. 

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, within the meaning of CAA 

section 112(d)(6), we analyzed the 

technical feasibility of applying these 

developments and the estimated costs, 

energy implications, non-air 

environmental impacts, as well as 

considering the emission reductions. 

We also considered the appropriateness 

of applying controls to new sources 

versus retrofitting existing sources. 

Based on our analyses of the available 

data and information, we identified 

potential developments in practices, 

processes and control technologies. For 

this exercise, we considered any of the 

following to be a ‘‘development’’: 

• Any add-on control technology or 

other equipment that was not identified 

and considered during development of 

the original MACT standards. 

• Any improvements in add-on 

control technology or other equipment 

(that were identified and considered 

during development of the original 

MACT standards) that could result in 

additional emissions reduction. 

• Any work practice or operational 

procedure that was not identified or 

considered during development of the 

original MACT standards. 

• Any process change or pollution 

prevention alternative that could be 

broadly applied to the industry and that 

was not identified or considered during 

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34As explained above, the EPA did not have POM 

emissions data for prebake potlines at the time of 

the December 2011 proposal. The EPA developed 

the POM emissions MACT floor limits for prebake 

potlines in that proposal by estimating POM 

emissions based on a ratio of POM emissions to TF 

emissions, an approach which found no support in 

the public comments. Today’s proposal is based 

entirely on the new emission data obtained since 

the December 2011 proposal. See section II.D, 

above. 

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). 

Since we are proposing some firsttime MACT standards in this action, we 

considered the same factors with respect 

to these proposed MACT standards. In 

addition to reviewing the practices, 

processes and control technologies that 

were considered at the time we 

originally developed (or last updated) 

the NESHAP, we also reviewed a variety 

of data sources in our investigation of 

potential practices, processes or controls 

to consider. Among the sources we 

reviewed were the NESHAP for various 

industries that were promulgated since 

the MACT standards being reviewed in 

this action. We reviewed the regulatory 

requirements and/or technical analyses 

associated with these regulatory actions 

to identify any practices, processes and 

control technologies considered in these 

efforts that could be applied to emission 

sources in the Primary 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. 

For the 2011 proposal, our initial 

technology review focused on the 

identification and evaluation of 

developments in practices, processes 

and control technologies that have 

occurred since the EPA promulgated the 

1997 NESHAP. We then made decisions 

on whether it is necessary to propose 

amendments to the 1997 NESHAP to 

require standards reflecting performance 

of the identified developments. Based 

on our analyses of the data and 

information collected and our general 

understanding of the industry and other 

available information on potential 

controls for this industry, we identified 

no developments in practices, processes 

and control technologies, other than the 

proposed startup work practices 

described in the December 2011 

proposal (76 FR 76260). 

Additional details regarding the 

previously conducted technology 

review can be found in the Draft 

Technology Review for Primary 

Aluminum Reduction Plants (Docket ID 

No. EPA–HQ–OAR–2011–0797–0149) 

and are discussed in the preamble to the 

December 2011 proposal (76 FR 76260). 

We conducted an additional review of 

developments in practices, processes 

and control technologies since the 2011 

proposal and updated the technology 

review to reflect changes in the number 

and type of currently operating and 

idled facilities. As noted, this analysis 

indicates what developments may be 

possible assuming the EPA adopts the 

proposed amendments to the MACT 

standards discussed in the following 

section of this preamble. The Revised 

Draft Technology Review for the 

Primary Aluminum Production Source 

Category is available in the docket 

(Docket ID No. EPA–HQ–OAR–2011– 

0797). 

IV. Revised Analytical Results and 

Proposed Decisions for the Primary 

Aluminum Production Source Category 

A. What actions are we proposing 

pursuant to CAA sections 112(d)(2) and 

112(d)(3)? 

As described previously, CAA section 

112(d) requires the EPA to promulgate 

technology-based NESHAP for listed 

source categories, including this source 

category. The EPA did so in the 1997 

primary aluminum NESHAP. As 

described above (in section II.B), the 

1997 NESHAP included MACT 

standards for TF from all types of 

existing and new potlines and bake 

furnaces and MACT standards for POM 

from existing and new Soderberg 

potlines, paste plants, bake furnaces and 

new pitch storage tanks. In the 2011 

proposal, we proposed emissions limits 

pursuant to CAA sections 112(d)(2) and 

(3) for a number of HAP or emissions 

points that were not previously covered 

by the NESHAP, including limits for 

POM from prebake potlines, COS from 

prebake and Soderberg potlines and 

POM from existing pitch storage tanks. 

After proposal, in response to the 2013 

CAA section 114 information request, 

we received a substantial amount of 

additional data on POM emissions from 

prebake potlines and therefore we reanalyzed the proposed limits for 

emissions of POM from prebake 

potlines.34 Based on those analyses we 

have determined it is appropriate to 

propose revised emission limits for 

POM from these existing potlines in 

these subcategories, and to propose 

different POM limits for new potlines. 

Additionally, after the 2011 proposal, 

in response to the 2013 CAA section 114 

information request, we received data 

regarding PM and HAP metals 

emissions from potlines, anode bake 

furnaces and paste plants. These 

pollutants are not covered by the 1997 

NESHAP. Based on those analyses, we 

have determined it is appropriate to 

propose emission limits for PM, as a 

surrogate for HAP metals, from existing 

potlines and new potlines, as well as 

from new and existing anode bake 

furnaces and new and existing paste 

plants. We have used PM as a surrogate 

for HAP metals in many other NESHAP 

(e.g., secondary aluminum, see 65 FR 

15692 (March 23, 2000), and Portland 

cement, 64 FR 31900 (June 14, 1999)). 

The agency believes PM is an 

appropriate surrogate for non-mercury 

HAP metals because those metals and 

particulate are captured 

indiscriminately by PM control 

technology. See National Lime Ass’n v. 

EPA, 233 F. 3d 625, 639 (D.C. Cir. 2000) 

(upholding use of PM as a surrogate for 

HAP metal for purposes of CAA section 

112(d) MACT standard). We do not 

consider TF to be a suitable surrogate 

for HAP metals since the HF portion of 

TF is very reactive and controlled very 

effectively via adsorption in dry 

alumina scrubbers in the Primary 

Aluminum Production source category. 

The HAP metals would not be as 

effectively controlled via these 

mechanisms and, therefore, we would 

not expect good correlation, for this 

source category, between HAP metal 

emissions and TF emissions. Similarly, 

we do not consider POM to be a suitable 

surrogate for HAP metals as POM is 

more effectively controlled via 

adsorption in the dry alumina scrubbers 

than HAP metals. Again, we would not 

expect good correlation, for this source 

category, between HAP metal emissions 

and POM emissions. See 61 FR 50592 

(Sept. 26, 1996). We expect better 

correlations may exist between these 

pollutants in some other source 

categories that use other types of control 

devices to minimize emissions. 

However, as explained above, we do not 

expect good correlation in the Primary 

Aluminum Production source category, 

which uses dry alumina scrubbers as a 

primary control technology and is the 

only source category we are aware of 

that controls emissions with dry 

alumina scrubbers. Therefore, we are 

proposing MACT limits for both POM 

and PM for Primary Aluminum 

Production sources in this action. 

In this section, we summarize how we 

developed the revised proposed 

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35See, e.g. Portland Cement Ass’n v. EPA, 665 F. 

3d 177, 189 (D.C. Cir. 2011). 

standards for POM emissions from 

prebake potlines and the newly 

proposed PM emission standards for 

potlines, anode bake furnaces and paste 

plants (including how we calculated 

MACT floors, how we accounted for 

variability in those floor calculations, 

and how we considered beyond-thefloor (BTF) options). For more 

information on these analyses, see the 

Revised Draft MACT Floor Analysis for 

the Primary Aluminum Production 

Source Category, which is available in 

the docket for this action (Docket ID No. 

EPA–HQ–OAR–2011–0797). 

With regard to Hg, D/F and PCBs, as 

discussed in section III.A.1 of this 

preamble, there are considerable 

limitations in the emissions data for 

these HAP. For example, many of the 

available emissions test results were 

reported as below detection limit (BDL) 

for these HAP. Furthermore, we have 

test data for PCBs and D/F for only one 

of the 11 prebake facilities. 

Nevertheless, based on the available 

data (including applying conservative 

assumptions that non-detectable Hg is 

actually emitted), we estimate that the 

total Hg emissions for the entire source 

category are less than 60 pounds per 

year and the average Hg emissions per 

facility are less than 5 pounds per year. 

We estimate the total D/F toxicity 

equivalent (TEQ) emissions for the 

entire source category are less than 7 

grams per year (again assuming that 

non-detectable D/F are actually emitted) 

and that the average D/F TEQ emissions 

per facility are less than 1 gram per year. 

Furthermore, there are significant 

uncertainties regarding these emissions 

and we have insufficient data to develop 

appropriate standards for these HAP. As 

discussed in section III.A.1 of this 

preamble, the EPA may, but is not 

obligated to, amend MACT standards 35

and, in the case of D/F, Hg and PCB, 

where data are insufficient to develop 

appropriate standards, the EPA is 

choosing not to propose standards for 

these HAP at this time. 

1. How do we develop MACT floor 

limits? 

As discussed in the 2011 proposal (76 

FR 76260), the MACT floor limit for 

existing sources is calculated based on 

the average performance of the best 

performing units in each category or 

subcategory, and also on a consideration 

of these units’ variability. The MACT 

floor for new sources is based on the 

single best performing source, with a 

similar consideration of that source’s 

variability. The MACT floor for new 

sources cannot be less stringent than the 

emissions performance that is achieved 

in practice by the best-controlled similar 

source. To account for variability in the 

operation and emissions, the stack test 

data were used to calculate the average 

emissions and the 99 percent upper 

prediction limit (UPL) to derive the 

MACT floor limits. For more 

information regarding the general use of 

the UPL and why it is appropriate for 

calculating MACT floors, see the 

memorandum titled, Use of the Upper 

Prediction Limit for Calculating MACT 

Floors (UPL Memo), which is available 

in the docket for this action (Docket ID 

No. EPA–HQ–OAR–2011–0797). 

Furthermore, with regard to calculation 

of MACT floor limits based on limited 

datasets, we considered additional 

factors as summarized below and 

described in more detail in the 

memorandum titled, Approach for 

Applying the Upper Prediction Limit to 

Limited Datasets for the Primary 

Aluminum Production Source Category 

(i.e., Limited Dataset Memo), which is 

available in the docket for this action. 

2. What is our approach for applying the 

UPL to limited datasets? 

The UPL approach addresses 

variability of emissions data from the 

best performing source or sources in 

setting MACT standards. The UPL also 

accounts for uncertainty associated with 

emission values in a dataset, which can 

be influenced by components, such as 

the number of samples available for 

developing MACT standards and the 

number of samples that will be collected 

to assess compliance with the emission 

limit. The UPL approach has been used 

in many environmental science 

applications. As explained in more 

detail in the UPL Memo, the EPA uses 

the UPL approach to reasonably 

estimate the emissions performance of 

the best performing source or sources to 

establish MACT floor standards. 

With regard to the derivation of 

MACT limits using limited datasets, in 

a recent DC Circuit Court of Appeals 

decision in National Association of 

Clean Water Agencies v. EPA (NACWA), 

734 F. 3d 1115 (2013), which involved 

challenges to the EPA’s MACT 

standards for sewage sludge 

incinerators, questions were raised by 

the court regarding the application of 

the UPL to limited datasets. We have 

since addressed these questions, as 

explained in detail in the Limited 

Dataset Memo, which is available in the 

docket for this action (Docket ID No. 

EPA–HQ–OAR–2011–0797). We seek 

comments on the approach described in 

the Limited Dataset Memo and whether 

there are other approaches we should 

consider for such datasets. 

3. How did we apply the approach for 

limited datasets to limited datasets in 

the Primary Aluminum Production 

source category? 

For the Primary Aluminum 

Production source category, we have 

limited datasets for the following 

pollutants and subcategories: POM and 

PM from existing CWPB2 potlines, 

CWPB3 potlines and SWPB potlines; 

POM and PM from all new potlines; and 

PM from new anode bake furnaces and 

paste production plants. Therefore, we 

evaluated these specific datasets to 

determine whether it is appropriate to 

make any modifications to the approach 

used to calculate MACT floors for each 

of these datasets. 

For each dataset, we performed the 

steps outlined in the Limited Dataset 

Memo, including: ensuring that we 

selected the data distribution that best 

represents each dataset; ensuring that 

the correct equation for the distribution 

was then applied to the data; and 

comparing individual components of 

each limited dataset to determine if the 

standards based on limited datasets 

reasonably represent the performance of 

the units included in the dataset. The 

results of each analysis are summarized 

below and described in more detail in 

the Limited Dataset Memo and in the 

Revised Draft MACT Floor Analysis for 

the Primary Aluminum Production 

Source Category document, which are 

available in the docket (Docket ID No. 

EPA–HQ–OAR–2011–0797). 

4. POM Emissions From Potlines 

a. Background 

As described above, since the 2011 

proposal, we obtained additional data 

on POM emissions from prebake 

potlines. In particular, we obtained data 

from eight facilities that operate prebake 

potlines, including at least one facility 

in each prebake potline subcategory. 

Today’s proposal is based exclusively 

on these new data, which the EPA 

regards as much more reliable than the 

data used in the 2011 proposal because 

the new data are based on direct testing 

of POM emissions, whereas the data 

used in the 2011 proposal were 

emissions estimates based on a ratio of 

POM emissions to TF emissions. Data 

were obtained from performance tests 

conducted by each of these facilities on 

both its primary control system exhaust 

and its secondary emissions. POM 

emissions are generated from 

volatilization of organic matter in 

anodes used to reduce alumina. All 

primary aluminum plants control these 

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36We are not reconsidering, reopening, or 

otherwise considering comment on the 

subcategorization structure for existing sources in 

this source category. 

POM emissions (and PM emissions) by 

capturing them from the area near the 

pots and directing them through a dry 

alumina scrubber, except for one plant 

which directs these emissions through 

wet scrubbers. The one plant with wet 

scrubbers produces a very high purity 

aluminum, is in a subcategory known as 

the Center-Worked Prebake 3 

subcategory, and is the only facility in 

that subcategory. Uncaptured 

(secondary) emissions of POM and PM 

are emitted from vents in the roof of the 

potroom. One plant operates wet roof 

scrubbers to control these secondary 

emissions. This is the sole facility in the 

Side-Worked Prebake subcategory. The 

MACT floor limits were determined 

based on the sum of the primary and 

secondary emissions. As in the current 

NESHAP and the 2011 proposal, these 

results are normalized to units of 

production, and expressed as pounds of 

pollutant (in this case, POM) per ton of 

aluminum produced (lb/ton aluminum). 

Pursuant to CAA sections 112(d)(2) 

and 112(d)(3), we are proposing to 

revise the 1997 NESHAP to include 

emission limits for POM emissions from 

prebake potlines. Regarding Soderberg 

potlines, the 1997 NESHAP already 

includes MACT limits for POM from 

Soderberg plants. Furthermore, the 

additional emissions data we gathered 

since the 2011 proposal do not support 

any revisions of the MACT limits for 

POM emissions from Soderberg potlines 

based solely on control technology 

considerations. Therefore, we are not 

proposing to revise the emissions limits 

for POM emissions from Soderberg 

potlines under CAA sections 112(d)(2), 

112(d)(3) or 112(d)(6) in today’s action. 

However, as described in section IV.C of 

this preamble, we also evaluated POM 

limits as part of our risk review and 

based on the results of the risk 

assessment we concluded that it was 

appropriate to tighten the POM limits 

for Soderberg facilities because of 

unacceptable risks. Therefore, as 

described in detail in section IV.C., we 

are proposing significantly tighter POM 

limits for Soderberg facilities based on 

our risk review pursuant to section 

112(f) of the CAA. 

b. Calculation of MACT Floors for POM 

for Potlines 

As discussed in the 2011 proposal 

and in section II.A of this preamble, the 

MACT floor for existing sources is based 

on the performance of best performing 

existing sources, and the MACT floor for 

new sources is based on the single best 

performing source. These MACT floor 

values include a calculation of 

variability calculated from these best 

performers’ test runs (76 FR 76260). 

More specifically, to account for normal 

variability in the operation and 

emissions, we calculated the MACT 

floors using the 99 percent UPLs. For 

more information regarding the use of 

the UPL and why it is appropriate for 

calculating MACT floors, see the UPL 

Memo. For more information on the 

calculation of the MACT floors for the 

Primary Aluminum Production source 

category, see the Revised Draft MACT 

Floor Analysis for the Primary 

Aluminum Production Source Category 

document, which is available in the 

docket (Docket ID No. EPA–HQ–OAR– 

2011–0797). 

With regard to new sources, as 

explained above, the MACT floor for 

new sources cannot be less stringent 

than the emissions performance that is 

achieved in practice by the bestcontrolled similar source. The EPA 

performed a variability analysis similar 

to that used for existing sources to 

calculate a 99 percent UPL using the test 

runs from the lowest emitting facility 

without regard to subcategory to derive 

the new source MACT floor limit. This 

new source MACT floor limit for POM 

emissions from potlines is lower (i.e., 

more stringent) than the MACT floor 

limit for POM emissions from existing 

potlines for all subcategories. We are not 

proposing separate emission limits for 

subcategories for new potlines because 

we expect that any new potlines will be 

designed to use the cleanest, most 

efficient technology available, or to 

improve capture and control systems to 

achieve emissions no greater than the 

best existing plant.36 A summary of the 

proposed MACT floor limits for POM is 

provided in Table 4. 

TABLE 4—PROPOSED MACT FLOOR

EMISSION LIMITS FOR POM FROM

POTLINES

Affected source 

Emission limit 

(in lb POM/ton 

aluminum) 

Existing CWPB1 Potlines ... 1 .1 

Existing CWPB2 Potlines ... 12 

Existing CWPB3 Potlines ... 2 .7 

Existing SWPB Potlines ..... 19 

New or Reconstructed 

Potlines ........................... 0 .77 

c. BTF Analysis for POM for Existing 

Potlines 

The next step in establishing MACT 

standards is the BTF analysis. In this 

step, we investigate other mechanisms 

for further reducing HAP emissions that 

are more stringent than the MACT floor 

level of control in order to ‘‘require the 

maximum degree of reduction in 

emissions’’ of HAP. In setting such 

standards, CAA section 112(d)(2) 

requires the agency to consider the cost 

of achieving the additional emission 

reductions, any non-air quality health 

and environmental impacts associated 

with more stringent standards and 

energy requirements associated with 

more stringent standards. Historically, 

these factors have included factors such 

as solid waste impacts of a control and 

the energy impacts of various potential 

control strategies. 

As described below, we considered 

BTF control options to further reduce 

emissions of POM. The BTF POM 

control options were developed based 

on the application of wet roof scrubbers 

to the 11 facilities that currently do not 

have them. 

We estimated the capital costs, 

annualized costs, emissions reductions 

and cost effectiveness for the BTF limits 

for this control technology. The details 

regarding how these limits were 

derived, and the estimated costs and 

expected reductions of POM and POM 

HAP through the installation of wet roof 

scrubbers, are provided in the Revised 

Draft Cost Impacts for the Primary 

Aluminum Production Source Category 

document, which is available in the 

docket (Docket ID No. EPA–HQ–OAR– 

2011–0797). 

Under this option (i.e., BTF controls 

for POM), we estimate the capital costs 

for installation and operation of the wet 

roof scrubbers at the 11 facilities would 

be $490 million, the annualized costs 

would be $155 million, and the controls 

would achieve about 1,000 tons per year 

of reductions in POM and 1.9 tons per 

year in speciated PAHs (a subset of 

POM). This results in an estimated cost 

effectiveness of about $155,000 per ton 

of POM and $82 million per ton of 

speciated PAHs. We believe our 

estimated costs are unacceptably high 

and not cost effective. When the 

primary aluminum NESHAP was 

proposed in 1996, we considered a cost 

effectiveness of $91,000 per ton of POM 

to be unacceptably high (Basis and 

Purpose Document for the Development 

of Proposed Standards for the Primary 

Aluminum Industry, July 19, 1996). 

Furthermore, industry sources provided 

additional information (Docket ID No. 

EPA–HQ–OAR–2011–0797, Johnson, 

C.D., Aluminum Association, July 9, 

2014) indicating that most existing 

prebake facilities would also likely 

require structural modification and 

reinforcement to accommodate the wet 

roof scrubbers, which could increase 

our estimated costs by 2 to 3 times, or 

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more. Note also that we have previously 

determined that there are technical 

problems with using these wet 

scrubbers at those facilities located in 

colder climates (see 62 FR 52392 (Oct. 

7, 1997)). Furthermore, based on our 

memo titled, Economic Impact Analysis 

for National Emissions Standards for 

Hazardous Air Pollutants: Primary 

Aluminum Reduction Plants, which is 

available in the docket (Docket ID No. 

EPA–HQ–OAR–2011–0797), we project 

that this option would pose significant 

economic burden on the companies and 

that several facilities would be at risk of 

closure under this option. There would 

also be collateral environmental impacts 

(more waste generated and more energy 

use), although these are not the most 

significant factors in the EPA’s proposed 

decision. 

Based on consideration of all the 

factors described above, we are not 

proposing BTF limits for POM 

emissions from existing sources. A 

summary of the estimated costs and 

reductions for the BTF option of wet 

scrubbers is provided in Table 5. 

TABLE 5—ESTIMATED COSTS AND REDUCTIONS FOR BTF CONTROL OPTIONS

Annualized costs 

($/yr) Pollutant Reduction (ton/yr) 

Cost 

effectiveness 

($/ton) 

Retrofit Wet Scrubber for Potline Secondary Emissions: 

$155 million ...................................................................................... POM ............................................... 1,000 155,000. 

Speciated PAHs ............................. 1.9 82 million. 

PM .................................................. 2,900 53,000. 

PM–HAP metals ............................. 23 6.73 million. 

Upgrade filter bags for anode bake furnaces: 

$7.9 million ....................................................................................... PM .................................................. 7.3 1.1 million. 

PM–HAP metals ............................. 0.027 292 million. 

Upgrade filter bags for paste plants: 

$560,000 ........................................................................................... PM .................................................. 5.31 110,000. 

PM–HAP metals ............................. 0.0058 96 million. 

Note: As described in sections above, the potline control costs shown in Table 5 could be 2 to 3 times higher or more because of need for 

building modifications and reinforcement to support the wet roof scrubbers. 

d. BTF Analysis for POM for New 

Potlines 

We estimate that a new primary 

aluminum plant of 200,000 ton per year 

capacity could install wet roof scrubbers 

for $28 million capital cost and $11 

million per year total annualized cost. 

This is equivalent to $55 per ton of 

aluminum. Assuming a new or 

reconstructed plant would be similar to 

the best performing existing source, we 

estimate that it would achieve 

reductions of 21 tons per year of POM 

by installing a wet roof scrubber. 

Therefore, the estimated cost 

effectiveness would be $540,000 per ton 

of POM reductions. We believe these 

costs and cost effectiveness are 

unacceptably high. Furthermore, the 

MACT floor level of control is based on 

the best performing existing source 

which already has relatively low POM 

emissions (which explains the poor cost 

effectiveness of further control). 

Therefore, we are not proposing BTF 

limits for emissions of POM from new 

or reconstructed sources. 

e. Proposed Standards for POM for 

Existing, New and Reconstructed 

Potlines 

Based on the results of all our 

analyses for existing, new and 

reconstructed sources, and after 

considering the estimated costs and 

reductions of the possible options for 

existing, new and reconstructed sources, 

we are proposing prebake potline 

emission standards for POM at the 

MACT floor for existing, new and 

reconstructed sources (as shown in 

Table 4). 

As discussed earlier, these MACT 

floor-based standards are based on the 

99 percent UPL. We estimate that all 

existing prebake potlines will be able to 

meet these MACT floor limits for POM 

without the need to install additional 

controls because the performance of all 

sources in the category is similar, all of 

the potlines within each of the 

subcategories utilize very similar 

emissions control technology and the 

average emissions from each source are 

well below the MACT floor limit. 

Therefore, in assessing the costs of the 

proposed MACT standards for potline 

POM emissions, the only associated 

additional costs we estimate are for 

compliance testing, monitoring and 

recordkeeping. 

5. PM Emissions From Potlines 

a. Background 

The 1997 NESHAP does not contain 

emission limits for HAP metals (or for 

a surrogate). However, as described 

above, since the 2011 proposal, we 

obtained significant amounts of data on 

PM emissions from potlines. In 

particular, we obtained PM data from 

nine prebake potline facilities 

(including at least one facility in each 

prebake potline subcategory) and one 

Soderberg facility when the facility was 

operating. We obtained data from each 

of these facilities from performance tests 

of both the primary control system 

exhaust and the secondary emissions. 

The PM emissions are generated from 

suspension of alumina feed material and 

the condensation or precipitation of 

metals, organic compounds and fluoride 

salts emitted from the pots. The PM 

includes HAP metals that are in 

particulate form (such as Ni, Cd, Cr, Pb, 

manganese (Mn) and As). The 

particulate HAP metals emitted by 

primary aluminum facilities are part of 

their PM emissions, and, as noted 

above, are captured indiscriminately by 

the PM control equipment. All primary 

aluminum plants control these 

emissions by capturing them from the 

area near the pots and directing them 

through a dry alumina scrubber, 

followed by a particulate control device, 

except for one facility which directs the 

captured emissions through a wet 

scrubber. This one facility is in the 

Center-Worked Prebake 3 potline 

subcategory which produces a very high 

purity aluminum and is the only facility 

in that subcategory. 

The uncaptured (secondary) PM 

emissions are emitted from vents in the 

roof of the potroom. One plant operates 

wet roof scrubbers which are assumed 

to provide some control (about a 50 

percent reduction) of these secondary 

emissions. This one facility is in the 

Side-Worked Prebake subcategory and is 

the only facility in the U.S. that is in 

that subcategory. 

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The MACT floor limits were 

determined based on the sum of the 

primary and secondary emissions. As in 

the current NESHAP, these results were 

normalized to units of production, and 

are expressed as pounds of pollutant (in 

this case, PM) per ton of aluminum 

produced. 

Pursuant to CAA sections 112(d)(2) 

and (3), we are proposing to revise the 

1997 NESHAP to include emission 

limits for PM emissions (as a surrogate 

for particulate HAP metals) from 

potlines. 

b. Calculation of MACT Floor Limits for 

PM for Potlines 

As described in sections II.A and 

IV.A.4.b of this preamble, the MACT 

floor limit reflects the performance of 

best performing sources for existing 

sources (or the single best performing 

source, for new sources), including a 

calculation of variability. More 

specifically, to account for variability, 

we calculated the MACT floors using 

the 99 percent UPL. For more 

information on how we calculated the 

MACT floors, see the Revised Draft 

MACT Floor Analysis for the Primary 

Aluminum Production Source Category 

document, which is available in the 

docket (Docket ID No. EPA–HQ–OAR– 

2011–0797). 

With regard to new sources, as 

explained above, the MACT floor cannot 

be less stringent than the emissions 

performance that is achieved in practice 

by the best-controlled similar source. 

The MACT floor limit for PM for new 

potlines was calculated based on the 99 

percent UPL using the test data from the 

lowest emitting facility without regard 

to subcategory. This new source MACT 

floor limit for PM emissions from 

potlines is lower (i.e., more stringent) 

than the MACT floor limit for PM 

emissions from existing potlines. This 

emission limit is based on the best 

performing source and is equal to the 

lowest emission limit proposed for any 

existing potline subcategory. We are not 

proposing subcategories for new 

potlines because we expect that any 

new potlines will be designed to use the 

cleanest, most efficient technology 

available, or to improve capture and 

control systems to achieve emissions no 

greater than the best existing plant. We 

are proposing that the MACT floor 

emissions limit for all types of new 

potlines will be based on the single best 

performing existing potline, which for 

PM is a potline at the SWPB facility. A 

summary of the MACT floor limits for 

PM for existing and new potlines is 

provided in Table 6. 

TABLE 6—MACT FLOOR EMISSION

LIMITS FOR PM FROM POTLINES

Affected source 

PM emission 

limit 

(lb PM/ton 

aluminum) 

Existing CWPB1 Potlines ... 7 .2 

Existing CWPB2 Potlines ... 11 

Existing CWPB3 Potlines ... 20 

Existing SWPB Potlines ..... 4 .6 

Existing VSS2 Potlines ....... 26 

New and Reconstructed 

Potlines ........................... 4 .6 

c. BTF Analysis for PM for Existing 

Potlines 

The next step in establishing MACT 

standards is the BTF analysis. In this 

step, we investigate other mechanisms 

for further reducing HAP emissions that 

are more stringent than the MACT floor 

level of control in order to ‘‘require the 

maximum degree of reduction in 

emissions’’ of HAP. In setting such 

standards, CAA section 112(d)(2) 

requires the agency to consider the cost 

of achieving the additional emission 

reductions, any non-air quality health 

and environmental impacts associated 

with more stringent standards and 

energy requirements associated with 

more stringent standards. 

As described below, we considered 

BTF control options to further reduce 

emissions of PM. The BTF PM control 

options were developed based on the 

application of wet roof scrubbers to the 

11 facilities that currently do not have 

them, which are the same BTF controls 

assessed for POM. 

We estimated the capital costs, 

annualized costs, emissions reductions 

and cost effectiveness for the BTF limits 

for this control technology. These are 

the same costs used for estimating POM 

control costs. The details regarding 

calculation of these estimated costs and 

expected reductions of PM and HAP 

metals through the installation of wet 

roof scrubbers are provided in the 

Revised Draft Cost Impacts for the 

Primary Aluminum Production Source 

Category document which is available 

in the docket (Docket ID No. EPA–HQ– 

OAR–2011–0797). 

Under this option (i.e., BTF controls 

for PM and HAP metals), we estimate 

the capital costs for 11 facilities to 

install and operate wet roof scrubbers 

would be about $490 million, 

annualized costs of about $155 million, 

and would achieve about 2,900 tons per 

year of reductions in PM, 780 tons per 

year of PM2.5 and 23 tons per year in 

HAP metals, which results in estimated 

cost effectiveness of about $200,000 per 

ton of PM2.5 and $6.7 million per ton of 

HAP metals. Furthermore, industry 

sources provided additional information 

(Docket ID No. EPA–HQ–OAR–2011– 

0797, Johnson, C.D., Aluminum 

Association, July 9, 2014) indicating 

that most existing prebake facilities 

would likely require structural 

modification and reinforcement to 

accommodate the wet roof scrubbers, 

which could increase our estimated 

costs by 2 to 3 times, or more. Therefore, 

we believe the costs for these BTF 

controls would be unacceptably high. 

Note also that we have previously 

determined that there are technical 

problems with using these wet 

scrubbers at those facilities located in 

colder climates (see 62 FR 52392, 

October 7, 1997). Furthermore, based on 

our Economic Impact Analysis for 

National Emissions Standards for 

Hazardous Air Pollutants: Primary 

Aluminum Reduction Plants, which is 

available in the docket (Docket ID No. 

EPA–HQ–OAR–2011–0797), we project 

that this option would pose significant 

economic burden on the companies and 

that several facilities would be at risk of 

closure. There would also be collateral 

environmental impacts (more waste 

generated and more energy use), 

although these are not significant factors 

in the EPA’s proposed decision. 

Based on consideration of all the 

factors described above, we are not 

proposing BTF limits for PM emissions 

from existing sources. A summary of the 

costs and reductions for the BTF option 

of wet scrubbers is provided in Table 5. 

d. BTF Analysis for PM for New 

Potlines 

We estimate that a new primary 

aluminum plant of 200,000 ton per year 

capacity could install wet roof scrubbers 

for $28 million per year capital cost and 

$11 million per year total annualized 

cost. This is equivalent to $55 per ton 

of aluminum. Assuming a new or 

reconstructed plant would be similar to 

the best performing existing source, we 

estimate that it would achieve 110 tons 

per year reductions of PM and 32 tons 

per year reductions of PM2.5 by 

installing a wet roof scrubber. Therefore, 

the estimated cost effectiveness would 

be $98,000 per ton of PM reductions and 

$350,000 per ton of PM2.5 reductions. 

We believe these costs are unacceptably 

high and not cost effective. Therefore, 

we are not proposing BTF limits for PM 

for new or reconstructed sources. 

e. Proposed Standards for PM for 

Existing, New and Reconstructed 

Potlines 

Based on the results of all our 

analyses for existing, new and 

reconstructed sources, and after 

considering the estimated costs and 

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reductions of the possible options for 

existing, new and reconstructed sources, 

we are proposing PM potline emission 

standards at the MACT floor for 

existing, new and reconstructed sources 

(as shown in Table 6). As discussed 

earlier, these MACT floor-based 

standards are based on the 99 percent 

UPL. We estimate that all existing 

prebake potlines will be able to meet 

these MACT floor limits for PM without 

the need to install additional controls 

because the performance of all sources 

in the category is similar, all of the 

potlines within each of the 

subcategories utilize very similar 

emissions control technology, the 

average emissions from each source are 

well below the MACT floor limit and 

emissions data from every facility that 

performed emissions testing were 

included in the dataset used to develop 

the MACT floor. Therefore, in assessing 

the costs of the proposed MACT 

standards for potline PM emissions, the 

only associated costs we estimate are for 

compliance testing, monitoring and 

recordkeeping. 

6. PM Emissions From Anode Bake 

Furnaces 

a. Background 

The 1997 NESHAP does not contain 

emission limits for HAP metals (or for 

a surrogate). However, as described 

above, we obtained significant data on 

PM emissions from anode bake furnaces 

since the 2011 proposal. In particular, 

we obtained data from 7 of the 8 anode 

bake furnaces presently in operation. 

Data were obtained by facilities from 

performance tests of their control device 

exhausts. As in the current NESHAP, 

these results are normalized to units of 

production, and expressed as pounds of 

pollutant (in this case, PM) per ton of 

green anode. PM emissions are 

generated from dust and condensed 

pitch hydrocarbons and fluorides 

generated when green anodes are baked. 

All currently operating anode bake 

furnaces are controlled with dry 

alumina scrubbers and fabric filters, 

which capture particulate HAP metals 

indiscriminately as a subset of total 

captured PM. 

Pursuant to CAA sections 112(d)(2) 

and (3), we are proposing to revise the 

1997 NESHAP to include emission 

limits for PM (as a surrogate for HAP 

metals) from anode bake furnaces. 

b. Calculation of MACT Floor Limits for 

PM for Anode Bake Furnaces 

We followed the same general 

approach, using the 99 percent UPL, to 

calculate MACT floor limits for anode 

bake furnaces as we used for the 

potlines (described in section IV.A.4.b 

of this preamble). Using this approach 

we calculate the MACT floor limit for 

existing anode bake furnaces to be 0.068 

lbs PM per ton of green anode (lbs/ton 

green anode). For more information on 

how we calculated the MACT floors, see 

the Revised Draft MACT Floor Analysis 

for the Primary Aluminum Production 

Source Category document, which is 

available in the docket (Docket ID No. 

EPA–HQ–OAR–2011–0797). 

With regard to new sources, as 

explained above, the MACT floor cannot 

be less stringent than the emissions 

performance that is achieved in practice 

by the best-controlled similar source. A 

variability analysis similar to that used 

for existing sources was then performed 

to calculate a 99 percent UPL using the 

test data from the lowest emitting 

facility. This new source MACT floor 

limit for PM emissions from anode bake 

furnaces is lower (i.e., more stringent) 

than the MACT floor limit for PM 

emissions from existing anode bake 

furnaces. The new source MACT floor 

limit is based on the performance of the 

best existing anode bake furnace. Using 

this approach, we calculate the MACT 

floor limit for new sources to be 0.036 

lbs/ton green anode. 

c. BTF Analysis for PM for Existing 

Anode Bake Furnaces 

The next step in establishing MACT 

standards is the BTF analysis. As 

described above, in this step, we 

investigate other mechanisms for further 

reducing HAP emissions that are more 

stringent than the MACT floor level of 

control in order to ‘‘require the 

maximum degree of reduction in 

emissions’’ of HAP. 

We considered BTF control options to 

further reduce emissions of PM from 

anode bake furnaces. The BTF PM 

control options were developed based 

on the replacement of cloth filter bags 

with membrane bags which are 

expected to provide better particulate 

control. 

We estimated the capital costs, 

annualized costs, emissions reductions 

and cost effectiveness for the BTF limits 

for this control technology. The details 

regarding how these limits were 

derived, and the estimated costs and 

expected reductions of PM and HAP 

metals through the replacement of 

conventional filter bags with membrane 

bags are provided in the Revised Draft 

Cost Impacts for the Primary Aluminum 

Production Source Category document, 

which is available in the docket (Docket 

ID No. EPA–HQ–OAR–2011–0797). 

Under this option (i.e., BTF controls 

for PM and HAP metals), we estimate 

annualized costs for 10 facilities of 

about $7.9 million. This option would 

achieve about 7.3 tons per year of 

reductions in PM and 0.027 tons per 

year of HAP metals, which results in 

estimated cost effectiveness of about 

$1.1 million per ton of PM and $292 

million per ton of HAP metals. We 

believe these costs and cost 

effectiveness are unacceptably high. 

There would also be collateral 

environmental impacts (more waste 

generated and more energy use), 

although these are not the most 

significant factors in the EPA’s proposed 

decision. Based on consideration of all 

the factors described above, we are not 

proposing BTF limits for PM emissions 

from existing sources. 

A summary of the costs and 

reductions for the BTF option based on 

the performance of fabric filters with 

membrane bag upgrades is given in 

Table 5. 

d. BTF Analysis for PM for New Bake 

Furnaces 

We estimate that a new primary 

aluminum plant of 200,000 ton per year 

capacity could use membrane filter bags 

in fabric filters used to control PM from 

anode bake furnaces for an incremental 

annualized cost of $680,000 per year. 

Cost effectiveness is expected to be 

comparable to that estimated for 

existing plants. We believe these costs 

and cost effectiveness are unacceptably 

high. Therefore, we are not proposing 

BTF limits for PM emissions from new 

anode bake furnaces. 

e. Proposed Standards for PM for 

Existing, New and Reconstructed Anode 

Bake Furnaces 

Based on the results of all our 

analyses for existing, new and 

reconstructed sources, and after 

considering the estimated costs and 

reductions of the possible options for 

existing, new and reconstructed sources, 

we are proposing a PM emission limit 

at the MACT floor for existing bake 

furnaces of 0.068 pounds of PM per ton 

of green anode (lbs PM/ton green anode) 

and we are proposing a MACT floor 

limit of 0.036 lbs PM/ton green anode 

for new and reconstructed sources. 

As discussed earlier, these MACT 

floor-based standards are based on the 

99 percent UPL. We estimate that all 

existing bake furnaces will be able to 

meet these MACT floor limits for PM 

without the need to install additional 

controls because the performance of all 

sources in the category is similar, all of 

these furnaces utilize very similar 

emissions control technology and the 

average emissions from each source for 

which we have reliable data are well 

below the MACT floor limit. Therefore, 

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the only additional costs are estimated 

to be for compliance testing, monitoring 

and recordkeeping. Therefore, in 

assessing the costs of the proposed 

MACT standards for PM for bake 

furnaces, the only associated costs we 

estimate are for compliance testing, 

monitoring and recordkeeping. 

7. PM Emissions From Paste Plants 

a. Background 

The 1997 NESHAP does not contain 

emission limits for emissions of HAP 

metals (or for a surrogate) from paste 

plants. However, as described above, we 

obtained a substantial amount of data on 

PM emissions from paste plants since 

the 2011 proposal. In particular, we 

obtained emissions test data from seven 

of the eight paste plants presently in 

operation. Data were obtained from tests 

of control device exhausts. As in the 

current NESHAP, these results are 

normalized to units of production, and 

expressed as pounds of pollutant (in 

this case, PM) per ton of green anode. 

All currently operating paste plants are 

controlled with dry coke scrubbers and 

fabric filters. PM emissions are 

generated from crushing and grinding 

coke and mixing ground coke with 

heated pitch to produce green anodes. 

Pursuant to CAA sections 112(d)(2) 

and (3), we are proposing to revise the 

1997 NESHAP to include emission 

limits for PM emissions from paste 

plants. 

b. Calculation of MACT Floor Limits for 

PM for Paste Plants 

We followed the same general 

approach, using the 99 percent UPL, to 

calculate MACT floor limits for paste 

plants as we used for the potlines 

(described in section IV.A.4.b of this 

preamble). Using this approach, we 

calculate the MACT floor limit for 

existing paste plants to be 0.082 lbs of 

PM per ton of green anode. For more 

information on how we calculated the 

MACT floors, see the Revised Draft 

MACT Floor Analysis for the Primary 

Aluminum Production Source Category 

document, which is available in the 

docket (Docket ID No. EPA–HQ–OAR– 

2011–0797). 

With regard to new sources, a 

variability analysis similar to that used 

for existing sources was then performed 

to calculate a 99 percent UPL using the 

test data from the lowest emitting 

facility. This new source MACT floor 

limit for PM emissions from paste plants 

is based on the best performing existing 

paste plant and is lower (i.e., more 

stringent) than the proposed MACT 

floor limit for PM emissions from 

existing paste plants. Using this 

approach, we calculate the MACT floor 

limit for new paste plants to be 0.0054 

lbs of PM/ton green anode. 

c. BTF Analysis for PM for Existing 

Paste Plants 

The next step in establishing MACT 

standards is the BTF analysis. In this 

step, we investigate other mechanisms 

for further reducing HAP emissions that 

are more stringent than the MACT floor 

level of control in order to ‘‘require the 

maximum degree of reduction in 

emissions’’ of HAP. 

We considered BTF control options to 

further reduce emissions of PM from 

paste plants. The BTF PM control 

options were developed based on the 

replacement of cloth filter bags with 

membrane bags which are expected to 

provide better particulate control. 

We estimated the capital costs, 

annualized costs, emissions reductions 

and cost effectiveness for the BTF limits 

for this control technology. We also 

considered if there were non-air 

environmental impacts or energy usage 

implications. The details regarding how 

these limits were derived, and the 

estimated costs and expected reductions 

of PM and HAP metals through the 

replacement of conventional filter bags 

with membrane bags are provided in the 

Revised Draft Cost Impacts for the 

Primary Aluminum Production Source 

Category document which is available 

in the docket (Docket ID No. EPA–HQ– 

OAR–2011–0797). 

Under this option (i.e., BTF controls 

for PM and HAP metals), we estimate 

the annualized costs for 11 facilities to 

be about $560,000, and would achieve 

about 5.3 tons per year of reductions in 

PM, 1.5 tons of reductions in PM2.5 and 

0.0058 tons per year of HAP metals. 

This results in estimated cost 

effectiveness of about $110,000 per ton 

of PM, $370,000 per ton of PM2.5 and 

$96 million per ton of HAP metals. We 

believe these costs and cost 

effectiveness are unacceptably high and 

minimal HAP reductions would be 

achieved. There would also be collateral 

environmental impacts (more waste 

generated and more energy use), 

although these are not significant factors 

in the EPA’s proposed decision. 

Therefore, we are not proposing BTF 

limits for PM emissions from existing 

paste plants. 

A summary of the costs and 

reductions for the BTF option of 

membrane bag upgrades is provided in 

Table 5. 

d. BTF Analysis for PM for New Paste 

Plants 

We estimate that a new primary 

aluminum plant with the capacity of 

200,000 ton per year could use 

membrane filter bags in fabric filters 

used to control PM from a paste plant 

for an incremental annualized cost of 

$51,000 per year, which would achieve 

approximately 0.0005 tpy reductions. 

This results in estimated cost 

effectiveness of about $98 million per 

ton of HAP metals. We believe these 

costs and cost effectiveness are 

unacceptably high, especially given that 

minimal HAP reductions would be 

achieved. Furthermore, the metal HAP 

emissions are already quite low from 

existing paste plants under the current 

NESHAP. Therefore, we are not 

proposing BTF limits for PM emissions 

from new or reconstructed paste plants. 

e. Proposed Standards for PM for 

Existing, New and Reconstructed Paste 

Plants 

Based on the results of all our 

analyses for existing, new and 

reconstructed sources, and after 

considering the estimated costs and 

reductions of the possible options for 

existing, new and reconstructed sources, 

we are proposing paste plant PM 

emission standards at the MACT floor 

for existing, new and reconstructed 

sources (as shown in Table 7). Since all 

of the paste plants utilize similar 

emissions control technology and the 

average emissions from each source 

were well below the MACT floor, all 

presently operating facilities are 

expected to meet the proposed MACT 

floor emission standards without the 

need to install additional controls. 

Therefore, in assessing the costs of the 

proposed MACT standards for PM for 

paste plants, the only associated costs 

we estimate are for compliance testing, 

monitoring and recordkeeping. 

A summary of the proposed MACT 

standards pursuant to CAA sections 

112(d)(2) and (3) for POM and PM for 

the various processes at primary 

aluminum reduction plants is provided 

in Table 7. 

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72942 Federal Register / Vol. 79, No. 235 / Monday, December 8, 2014 / Proposed Rules 

TABLE 7—PROPOSED MACT EMISSION LIMITS FOR POM AND PM FOR PRIMARY ALUMINUM REDUCTION PLANTS

PURSUANT TO SECTION 112(d)(2) 

Affected source Pollutant Emission limit 

Existing CWPB1 Potlines ............................................................ POM ............. 1.1 lb/ton aluminum. 

Existing CWPB2 Potlines ............................................................ POM ............. 12 lb/ton aluminum. 

Existing CWPB3 Potlines ............................................................ POM ............. 2.7 lb/ton aluminum. 

Existing SWPB Potlines .............................................................. POM ............. 19 lb/ton aluminum. 

New or Reconstructed Potlines ................................................... POM ............. 0.77 lb/ton aluminum. 

Existing CWPB1 Potlines ............................................................ PM ................ 7.2 lb/ton aluminum. 

Existing CWPB2 Potlines ............................................................ PM ................ 11 lb/ton aluminum. 

Existing CWPB3 Potlines ............................................................ PM ................ 20 lb/ton aluminum. 

Existing SWPB Potlines .............................................................. PM ................ 4.6 lb/ton aluminum. 

Existing VSS2 Potlines ................................................................ PM ................ 26 lb/ton aluminum. 

New and Reconstructed Potlines ................................................ PM ................ 4.6 lb/ton aluminum. 

Existing Bake Furnaces .............................................................. PM ................ 0.068 lb/ton green anode.

New Bake Furnaces .................................................................... PM ................ 0.036 lb/ton green anode. 

Existing Paste Plants .................................................................. PM ................ 0.082 lb/ton green anode. 

New and Reconstructed Paste Plants ........................................ PM ................ 0.0056 lb/ton green anode. 

B. What are the results of the risk 

assessment and analyses? 

1. Inhalation Risk Assessment Results 

Table 8 provides an overall summary 

of the results of the inhalation risk 

assessment. 

TABLE 8—PRIMARY ALUMINUM PRODUCTION SOURCE CATEGORY INHALATION RISK ASSESSMENT RESULTS

Maximum individual 

cancer risk 

(-in-1 million) a

Estimated population at increased risk levels of cancer 

Estimated annual 

cancer incidence 

(cases per year) 

Maximum chronic non-cancer 

TOSHI b

Refined maximum acute noncancer HQ c

Actual Emissions 

70 ............................... ≥ 1-in-1 million: 881,000 ...........

≥ 10-in-1 million: 65,000 ...........

≥ 100-in-1 million: 0 ..................

0.06 1 Cadmium and Nickel Compounds.HQREL = 10 (Arsenic Compounds). 

Residential. 

Allowable Emissions d

300 ............................. ≥ 1-in-1 million: 950,000 ...........

≥ 10-in-1 million: 76,000 ...........

≥ 100-in-1 million: 200 ..............

0.06 2 Nickel and Arsenic Compounds.

aEstimated maximum individual excess lifetime cancer risk due to HAP emissions from the source category. 

b Maximum TOSHI. The target organ with the highest TOSHI for the Primary Aluminum Production source category for actual emissions is the 

kidney and respiratory system and for allowable emissions is the respiratory, immunological and developmental systems. cThe maximum off-site HQ acute value of 10 at a residential location for actuals is driven by emissions of As from the potline roof vents. See 

section III.A.3 of this preamble for explanation of acute dose-response values. Acute assessments are not performed on allowable emissions. dThe development of allowable emission estimates can be found in the memoranda titled, Revised Draft Development of the RTR Emissions 

Dataset for the Primary Aluminum Production Source Category which is available in the docket. 

The inhalation risk modeling 

performed to estimate risks based on 

actual and allowable emissions relied 

primarily on emissions data from the 

information requests. The results of the 

chronic baseline inhalation cancer risk 

assessment indicate that, based on 

estimates of current actual emissions, 

the maximum individual lifetime cancer 

risk (MIR) posed by the Primary 

Aluminum Production source category 

is 70-in-1 million, with As, Ni and Cr+6

compounds from the potline roof vents 

accounting for 99 percent of the MIR. 

The total estimated cancer incidence 

from primary aluminum production 

sources based on actual emission levels 

is 0.06 excess cancer cases per year, 

with emissions of As, Ni and Cr+6

compounds contributing 64 percent, 21 

percent and 8 percent, respectively, to 

this cancer incidence. In addition, we 

note that approximately 900,000 people 

are estimated to have cancer risks 

greater than or equal to 1-in-1 million as 

a result of actual emissions from this 

source category, with 65,000 people 

having cancer risks greater than 10-in-1 

million. 

When considering MACT-allowable 

emissions, the maximum individual 

lifetime cancer risk is estimated to be up 

to 300-in-1 million, driven by potential 

emissions of As, Ni and PAH 

compounds from the potline roof vents 

of the one idle Soderberg facility. The 

estimated cancer incidence is estimated 

to be 0.06 excess cancer cases per year. 

Approximately 950,000 people were 

estimated to have potential cancer risks 

greater than or equal to 1-in-1 million 

considering allowable emissions from 

primary aluminum plants with 76,000 

people with potential cancer risks 

greater than 10-in-1 million and 200 

people with potential cancer risks 

greater than 100-in-1 million. The 

maximum modeled chronic non-cancer 

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37Burger, J. 2002. Daily Consumption of Wild 

Fish and Game: Exposures of High End 

Recreationists. International Journal of 

Environmental Health Research 12:343–354. 38U.S. EPA. Exposure Factors Handbook 2011 

Edition (Final). U.S. Environmental Protection 

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

2011. 

39As noted earlier, mercury values used in the 

analysis are likely to be inflated because EPA 

assumed mercury was emitted even from sources 

where no mercury was detected. 

40As noted earlier, D/F emissions used in this 

analysis are likely to be overstated because EPA 

imputed values for D/F congeners even from plants 

and process units where those D/F congeners were 

not detected in the emissions tests. 

HI (TOSHI) value based on actual 

emissions was estimated to be 1, for 

both Ni and Cd compounds emissions 

from the potline roof vents. When 

considering MACT-allowable emissions, 

the maximum chronic non-cancer 

TOSHI value was estimated to be 2, for 

both Ni and As compounds from potline 

roof vent emissions. 

2. Acute Risk Results 

Worst-case acute HQs were calculated 

for every emitted HAP that has an 

appropriate acute benchmark. For cases 

where the screening HQ was greater 

than 1, we further determined the 

highest HQ value that might occur 

outside facility boundaries. Based on 

estimated actual peak baseline 

emissions, the highest off-site acute 

screening HQ is 30 for As and the 

highest off-site acute screening HQ for 

HF is 3. 

We refined the acute As assessment 

by evaluating exposures at the centroids 

of census blocks—these are locations 

around the facilities where people could 

actually live. Based on this refinement, 

the maximum HQ was 10, for As. We 

estimate that about 170 people could be 

exposed to concentrations leading to an 

acute HQ of 10 for As, about 1,500 

people could be exposed to a 

concentration leading to an acute HQ 

greater than 5, and that about 8,500 

people could be exposed to a 

concentration leading to an acute HQ 

greater than 1. This assessment still 

assumes in order to reach an HQ greater 

than 1 that peak emissions from the 

source category and worst-case 

meteorological conditions co-occur. We 

then assume further that an individual 

will be present to be exposed at that 

time. These are a conservative series of 

assumptions. We expect that this would 

happen for very few hours of the 8,760 

hours that are in a year. 

We did not conduct any refinements 

to the HF acute screen because the 

maximum off-site HQ of 3 is at a 

location where we would not expect 

people to be for 1 hour. For more details 

see the Residual Risk Assessment for the 

Primary Aluminum Production Source 

Category in Support of the 2014 

Supplemental Proposal, which is 

available in the docket (Docket ID No. 

EPA–HQ–OAR–2011–0797). 

3. Multipathway Risk Screening Results 

Results of the worst-case Tier 1 

screening analysis indicate that 13 

facilities exceeded the PB–HAP 

emission screening rates (based on 

estimates of actual emissions) for D/F, 

Hg and PAH with six facilities 

exceeding the screening rate for Cd. For 

the PB–HAPs 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 

conservative, high-end assumptions 

about consumption of local fish and 

locally grown or raised foods (adult 

female angler at 99th percentile 

consumption for fish 37 for the 

subsistence fisherman scenario and 90th 

percentile for consumption of locally 

grown or raised foods 38 for the farmer 

scenario) which, as noted above, may 

not occur for this source category. 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 

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 this Tier 2 non-cancer 

screening analysis, emissions of Hg 39

and Cd exceeded the site-specific levels 

for those PB–HAP by a factor of 2 from 

two different facilities. With regard to 

the Tier 2 cancer screening analysis, 10 

facilities have estimated D/F emissions, 

as 2,3,7,8-tetrachlorodibenzo-p-dioxin 

TEQ, above the Tier 2 cancer screening 

thresholds and 12 facilities have 

estimated PAH emissions, as 

benzo(a)pyrene (BaP), above the Tier 2 

cancer screening threshold. The highest 

cancer exceedance for D/F was 40 times 

and 7 times for PAH’s for the 

subsistence fisherman scenario (total 

cancer screen value of 50 for the MIR 

site). Thus, these results indicate that 

the maximum cancer risks due to 

multipathway exposures to D/F and 

PAH emissions for the subsistence 

fisher scenario are less than 50-in-1 

million.40 For the subsistence farmer 

scenario, the highest cancer exceedance 

for D/F was 10 times and PAHs was 4 

times (total cancer screen value of 20 for 

the MIR site). 

Results of the analysis for Pb 

compounds indicate that based on the 

baseline, actual emissions, the 

maximum annual off-site ambient Pb 

concentration was below the primary 

NAAQS for Pb. 

4. Environmental Risk Screening Results 

We conducted an environmental risk 

screening assessment for the Primary 

Aluminum Production source category 

for the following HAP: Cd, Hg, PAHs, D/ 

F and HF. The results of the 

environmental screening analysis are 

summarized in Table 9. 

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TABLE 9—SUMMARY OF ENVIRONMENTAL RISK SCREEN RESULTS FOR THE PRIMARY ALUMINUM PRODUCTION SOURCE

CATEGORY

Number of facilities in category exceeding Percent of modeled area in 

category exceeding 2

Environmental HAP Tier 1 Screen Tier 2 Screen 1 NOAEL 

(%) 

LOAEL 

(%) 

NOAEL LOAEL NOAEL LOAEL 

PB–HAP ................................ D/F ........................................ None None 0.40 0 

MeHg .................................... None None 0 0 

Cd ......................................... 1 1 None None 0 0 

PAH ...................................... 1 1 1 None 4 NA 0 

Acid Gases ........................... HF 3 ....................................... NA None NA 0.2 

1Tier 2 screen is performed for PB–HAP when there are exceedances of the Tier 1 screen. The acid gas screen is a one tier screen. 2A value of 0% indicates that none of the modeled data points exceeded the benchmark. For PB–HAP the percent area is based on the Tier 2 

results, if a Tier 2 analysis is performed. Otherwise, the percent area is based on the Tier 1 results. 3For HF, we evaluated two benchmarks, one from Canada and the other from the state of Washington. Although, they are both considered to 

be LOELs—the level between a NOAEL and a LOAEL, we have listed the results under the LOAEL column for the Canadian benchmark, which 

is the more protective of the two. 4One facility had a Tier 2 exceedance for the sediment NOAEL benchmark at one lake. For PB–HAP the percent area is calculated for soil 

benchmarks only. 

NA = Not Applicable. MeHg = methylmercury. 

In our Tier 1 analysis, emissions of D/ 

F and methylmercury did not exceed 

the threshold emission rates for any of 

the ecological benchmarks for any 

facility in the source category. In our 

Tier 1 analysis, emissions of Cd and 

PAHs exceeded some ecological 

benchmarks for one facility. Therefore, 

we performed a Tier 2 analysis. In the 

Tier 2 analysis, emissions of Cd did not 

exceed the threshold emission rates for 

any of the ecological benchmarks for 

any facility in the source category. In 

the Tier 2 analysis, emissions of PAHs 

exceeded the NOAEL sediment 

benchmark for one lake by 2 times, but 

did not exceed the threshold effect 

level. For 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 the ecological benchmarks. 

For Pb compounds, we did not estimate 

any exceedances of the secondary Pb 

NAAQS. 

5. Facility-Wide Risk Assessment 

Results 

The facility-wide chronic MIR and 

TOSHI are based on actual emissions 

from all sources. Considering facilitywide emissions, the MIR is estimated to 

be 70-in-1 million driven by As, Ni and 

Cr+6 emissions and the chronic noncancer TOSHI value is calculated to be 

1 driven by emissions of Cd 

compounds. In both cases, the source of 

these emissions are from potline roof 

vents. 

6. Multipathway Refined Risk Results 

In the Tier 2 screening, emissions of 

Cd exceeded the fisher threshold at 

Alcoa in Ferndale, WA (NEIWA19906), 

and emissions of Hg exceeded the fisher 

threshold at Alumax in Goose Creek, SC 

(NEI41217) by a factor of 2. We also 

conducted a refined risk assessment for 

the Reynolds Metals (Alcoa—Massena 

East) (NEI46970) plant in Massena, NY. 

For more details on these assessments, 

see the Residual Risk Assessment for the 

Primary Aluminum Production Source 

Category in Support of the 2014 

Supplemental Proposal, which is 

available in the docket (Docket ID No. 

EPA–HQ–OAR–2011–0797). We then 

proceeded to a Tier 3 screen. We 

examined the set of lakes from which 

the (hypothetical) fisher ingested 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 which 

critical lakes were fishable and their 

respective adjustment to the Tier 2 

values, we analyzed plume rise data. All 

three of these sites required plume rise 

analysis. Approximately, 33 percent of 

the Cd emissions at NEIWA19906 and 

six percent of the Hg emissions at 

NEI41217 were lost due to plume rise, 

resulting in the Tier 2 non-cancer 

screening values for both sites for the 

fisher scenario going from 2 to 1. 

Reynolds Metals (NEI46970) 

permanently ceased operating their 

Soderberg process in March of 2014. 

The multipathway and inhalation risk 

characterization for this site will not be 

reflective of any future operations that 

may be conducted at this site, but 

provides valuable information showing 

how, through the use of more efficient 

and cleaner technologies, the industry 

has improved its environmental 

performance. This facility had the 

highest Tier 2 cancer screen value for 

the source category based upon actual 

emissions of PAHs and D/F with a value 

of 70 for the subsistence fisher scenario 

and a value of 200 for the subsistence 

farmer scenario. 

An analysis of the fishable lakes did 

not change the Tier 2 cancer screening 

values, and analysis of the hourly 

plume-rise data resulted in only 4 

percent of the mass being lost to the 

upper air sink. The Tier 3 screen did not 

reduce the Tier 2 cancer screen values 

for either PAH’s or D/F for this facility. 

The subsistence fisher and subsistence 

farmer scenarios are conservative 

screens that provide upper bound 

estimates of screening values with high 

levels of uncertainty. The multipathway 

scenarios for the Tier screens include 

some hypothetical elements, namely the 

location and actual site-specific 

ingestion rates for exposed individuals. 

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 

for each site. With regard to the farmer 

scenario, the uncertainty is even higher 

due to lack of site-specific information 

on where sustainable farms are located 

in addition to the make-up and 

quantities of food ingested. 

7. Demographic Analysis Results 

To examine the potential for any 

environmental justice (EJ) issues that 

might be associated with the source 

category, we performed a demographic 

analysis, which is an assessment of risks 

to individual demographic groups, of 

the population close to the facilities. In 

this analysis, we evaluated the 

distribution of HAP-related cancer risks 

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41 1-in-10 thousand is equivalent to 100-in-1 

million. The EPA currently describes cancer risks 

as ‘‘n-in-1 million.’’ 

and non-cancer hazards from the 

Primary Aluminum Production source 

category across different social, 

demographic and economic groups 

within the populations living near 

facilities identified as having the highest 

risks. The methodology and the results 

of the demographic analyses are 

included in a technical report, Risk and 

Technology Review—Analysis of SocioEconomic Factors for Populations Living 

Near Primary Aluminum Facilities, 

which is available in the docket for this 

action (Docket ID No. EPA–HQ–OAR– 

2011–0797). 

The results of the demographic 

analysis are summarized in Table 10 

below. These results, for various 

demographic groups, are based on the 

estimated risks from actual emissions 

levels for the population living within 

50 km of the facilities. The results 

(shown in Table 10) indicate there are 

no significant disproportionate risks to 

any particular minority, low income, or 

indigenous population. The results of 

the Primary Aluminum Production 

source category demographic analysis 

indicate that emissions from the source 

category expose approximately 881,307 

people to a cancer risk at or above 1-in1 million. The percentages of the at-risk 

population in each demographic group 

(except for White and non-Hispanic) are 

similar to or lower than their respective 

nationwide percentages. 

TABLE 10—PRIMARY ALUMINUM PRODUCTION SOURCE CATEGORY DEMOGRAPHIC RISK ANALYSIS RESULTS

Nationwide 

Population with 

cancer risk at or 

above 1-in-1 million 

Population with 

chronic hazard 

index above 1 

Total Population ..................................................................................................... 312,861,265 881,307 0 

Race by Percent 

White ...................................................................................................................... 72 80 0 

All Other Races ..................................................................................................... 28 20 0 

Race by Percent 

White ...................................................................................................................... 71 .9 80 .1 0 

African American ................................................................................................... 13 13 0 

Native American .................................................................................................... 1 .1 0 .9 0 

Other and Multiracial ............................................................................................. 14 6 0 

Ethnicity by Percent 

Hispanic ................................................................................................................. 17 5 0

Non-Hispanic ......................................................................................................... 83 95 0 

Income by Percent 

Below Poverty Level .............................................................................................. 14 14 0 

Above Poverty Level .............................................................................................. 86 86 0 

Education by Percent 

Over 25 and without High School Diploma ........................................................... 15 14 0 

Over 25 and with a High School Diploma ............................................................. 85 86 0 

C. 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 maximum 

individual lifetime cancer risk (MIR) of 

approximately 1 in 10 thousand [41].’’ 

(54 FR 38045, September 14, 1989.) 

In this proposal, the EPA estimated 

risks based on both actual and allowable 

emissions from primary aluminum 

facilities. 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 sources regulated by 

subpart LL is 70-in-1 million based on 

actual emissions from prebake facilities. 

The estimated incidence of cancer due 

to inhalation exposures is 0.06 excess 

cancer cases per year, or 1 case every 17 

years. Approximately 881,000 people 

face an estimated increased cancer risk 

greater than 1-in-1 million due to 

inhalation exposure to actual HAP 

emissions from the Primary Aluminum 

Production source category, and 

approximately 65,000 people face an 

estimated increased risk greater than 10- 

in-1 million and up to 70-in-1 million. 

The agency estimates that the maximum 

chronic non-cancer TOSHI from 

inhalation exposure is 1. As, Ni, Cd and 

chromium (Cr) are the main HAP 

contributing to the estimated chronic 

cancer and chronic non-cancer risks. 

The Tier 2 multipathway screening 

analysis of actual emissions from 

operating plants indicates the potential 

for PAH and D/F emissions is about 50 

times the screening level for cancer for 

the fisher scenario and 20 times the 

cancer threshold for the farming 

scenario. These results indicate that the 

maximum cancer risks due to 

multipathway exposures to D/F and 

PAH emissions from this source 

category are less than 50-in-1 million. 

Non-cancer impacts from Cd and Hg 

were at the Tier 2 screening thresholds, 

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which indicates that the maximum HI 

due to multipathway exposures to Hg 

and Cd emissions from this source 

category is less than 1. 

As noted above, the Tier 2 

multipathway screen is conservative in 

that it incorporates many healthprotective assumptions (and, as noted, 

reflects further assumptions here as to 

amounts of certain HAP being emitted). 

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 

exhibits ingestion behavior that would 

lead to a high total exposure. A Tier 2 

exceedance cannot be equated with a 

risk value or a HQ or HI. Rather, it 

represents a high-end bounding estimate 

of what the risk or hazard may be. For 

example, an exceedance of 2 for a noncarcinogen can be interpreted to mean 

that we have high confidence that the HI 

would be lower than 2. Similarly, an 

exceedance 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 health-protective, 

assumptions that are used in the Tier 2 

screen. 

The refined multipathway analysis 

that the EPA conducted for one specific 

Soderberg facility which has recently 

permanently shut down its Soderberg 

potlines found that the Tier 3 cancer 

screen resulted in the same potential 

risk as identified in the Tier 2 analysis 

with a cancer screen value of 70 for the 

subsistence fisher and 200 for the 

subsistence farmer. These results 

indicate that the maximum cancer risks 

due to multipathway exposures to 

emissions from that facility could have 

been up to 200-in-1 million. However, 

since that plant has permanently ceased 

operations of the Soderberg potlines 

(i.e., the emissions sources that were 

driving the risk at that facility), the 

future risks due to emissions at this 

location (i.e., if the company decides to 

replace its Soderberg potlines with 

lower-emitting prebake potlines and 

resume operations) will be substantially 

less than 100-in-1 million. 

The assessment of maximum acute 

inhalation impacts from baseline actual 

peak emissions (i.e., based on the 

standards in the 1997 NESHAP and the 

proposed standards in the 2011 

proposal and this supplemental 

proposal) indicates the potential for As 

to exceed an HQ value of 1 based on the 

REL value, with an estimated maximum 

off-site acute HQ of 30 based on the REL 

value and 10 at a residential location. 

There are no AEGL values for 

comparison. We refined the acute As 

assessment by evaluating exposures at 

the centroids of census blocks—these 

are locations around the facilities where 

people could actually live. Based on this 

refinement, the maximum HQ was 10. 

We estimate that about 170 people 

could be exposed to concentrations 

leading to an acute HQ of 10, about 

1,500 people could be exposed to a 

concentration leading to an acute HQ 

greater than 5, and about 8,500 people 

could be exposed to a concentration 

leading to an acute HQ greater than 1. 

This assessment still assumes in order 

to reach an HQ greater than one, peak 

emissions from each emission source at 

the source category and worst-case 

meteorological conditions co-occur at a 

time when an individual is present. In 

other words, the analysis includes the 

conservative assumption that every 

process releases its peak emissions at 

the same hour as the worst-case 

dispersion conditions. We expect that 

this would happen for very few hours of 

the 8,760 hours that are in a year. 

We did not conduct any refinements 

to the HF acute screen because the 

maximum off-site HQ of 3 is at a 

location where we would not expect 

people to be for 1 hour. 

For more information, refer to 

Appendix 8 of the Residual Risk 

Assessment for the Primary Aluminum 

Production Source Category in Support 

of the 2014 Supplemental Proposal 

(Docket ID No. EPA–HQ–OAR–2011– 

0797). 

b. Estimated Risks from Allowable 

Emissions 

The EPA estimates that the baseline 

inhalation cancer risk to the individual 

most exposed to emissions from sources 

regulated by subpart LL is up to 300-in1 million based on allowable emissions 

from Soderberg facilities, with As, Ni 

and POM driving the risks. The EPA 

estimates that the incidence of cancer 

due to inhalation exposures could be up 

to 0.06 excess cancer cases per year, or 

1 case approximately every 17 years. 

About 950,000 people could face an 

increased cancer risk greater than 1-in1 million due to inhalation exposure to 

allowable HAP emissions from this 

source category (assuming facilities emit 

at allowable levels for much of their 

operations, a highly conservative 

assumption), and approximately 76,000 

people could face an increased risk 

greater than 10-in-1 million and 200 

people to excess cancer risks up to 300- 

in-1 million due to allowable emissions. 

The risk assessment estimates that the 

maximum chronic non-cancer TOSHI 

from inhalation exposure values is up to 

2, driven by allowable Ni and As 

emissions with approximately 30 people 

exposed at this value. 

c. Acceptability Determination 

In proposing a determination of 

whether risks are acceptable for this 

source category, the EPA considered all 

available health information and risk 

estimation uncertainty as described 

above. 

The risk results indicate that actual 

inhalation cancer risks from the Primary 

Aluminum Production source category 

to the individual most exposed are up 

to, but no greater than, approximately 

70-in-1 million and that allowable 

inhalation cancer risks to the individual 

most exposed are up to, but no greater 

than, approximately 300-in-1 million, 

which is 3 times higher than the 

presumptive limit of acceptability. The 

MIR based on actual emissions is well 

below the presumptive limit, while the 

MIR based on allowable emissions is 

well above the presumptive limit. The 

maximum chronic non-cancer results 

show no exceedance of the human 

health values for actual emissions and 

exceedance by up to a factor of 

approximately 2 based on allowable 

emissions. 

Regarding the acute risks, the refined 

maximum HQ at a residential location is 

10 for As. We expect that these 

exceedances would happen for very few 

hours of the 8,760 hours that are in a 

year. For HF the maximum off-site HQ 

of 3 is at a location where we would not 

expect people to be for 1 hour. 

The excess cancer risks from the 

multipathway screen from actual D/F 

emissions from operating plants 

indicate that the risk to the individual 

most exposed could be up to but no 

greater than 50-in-1 million for the 

fisher scenario and 20-in-1 million for 

the farmer scenario. These results 

(which reflect very conservative 

assumptions) are considerably less than 

100-in-1 million, the presumptive limit 

of acceptability. The multipathway Tier 

2 screen for non-cancer is at the Tier 2 

screening value of 1 for Hg and Cd. The 

estimated cancer risks from the 

multipathway assessment for operating 

facilities were well below 100-in-1 

million. The refined multipathway 

results for the Massena East Soderberg 

plant indicated potential cancer risks of 

up to 200-in-1 million at that location. 

However, since this facility has 

permanently shut down its Soderberg 

operations, we are not concerned about 

the potential future emissions from this 

facility. 

Nevertheless, given all the 

information presented above, the EPA 

proposes that the risks due to potential 

HAP emissions at baseline from the 

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Soderberg subcategory are unacceptable 

due to the allowable cancer risks of 300- 

in-1 million based on potential 

emissions from the idle Soderberg 

facility (Columbia Falls Aluminum 

Company). 

Regarding the prebake subcategories, 

the EPA has some concerns regarding 

the potential acute risks due to As 

emissions (with a maximum acute HQ 

of 10). However, given the conservative 

nature of the acute analysis (described 

above), and the fact that the inhalation 

cancer MIR is well below 100-in-1 

million (MIR = 70-in-1 million), the 

chronic non-cancer risks are low (e.g., 

HI = 1) and that the multipathway 

assessment indicated the maximum 

cancer risks due to multipathway 

exposures to HAP from prebake 

facilities was no higher than 50-in-1 

million, we propose that the risks due 

to actual emissions from the prebake 

subcategories are acceptable. 

2. Proposed Controls To Address 

Unacceptable Risks for Soderberg 

Facilities 

a. VSS2 Potline Emissions 

In order to ensure that the risks 

associated with Soderberg facilities are 

acceptable, we evaluated the potential 

to reduce MACT-allowable VSS2 

potline emissions for the primary HAP 

driving the cancer risks (i.e., POM, As 

and Ni). Regarding POM, the current 

NESHAP includes an emissions limit for 

POM of 5.7 lbs/ton of aluminum. As 

noted above, the one facility driving the 

allowable risks has been idle for 5 years. 

All indications are that this facility will 

not reopen. However, based on available 

data from the most recent years that 

they were operating, we estimate that if 

this one VSS2 facility did reopen and if 

they installed wet roof top scrubbers 

that they could achieve a POM 

emissions limit of 1.9 lb/ton (0.85 Kg/ 

Mg) of aluminum, which would be a 

significant reduction in potential POM 

emissions. This limit is 3 times lower 

than the current limit for POM. 

Furthermore, given that there would be 

variability in emissions, in order for the 

facility to comply with a limit of 1.9 lbs/ 

ton at all times, they would need to 

have average POM emissions 

considerably lower than 1.9 lb/ton. 

Therefore, under the authority of CAA 

section 112(f)(2), we propose a POM 

emission limit for VSS2 potlines of 1.9 

lb/ton (0.85 Kg/Mg) of aluminum. As 

mentioned above, the one remaining 

Soderberg plant has been idle for 5 years 

and we believe it is highly unlikely that 

the facility will reopen, due to its less 

efficient aluminum production method. 

However, if it does reopen, we estimate 

that the capital costs for the roof top wet 

scrubbers would be about $30 million 

and that annualized costs would be 

about $8 million. 

These controls would also achieve 

reductions of HAP metal emissions. We 

estimate that wet roof scrubbers would 

achieve a 50 percent reduction in 

secondary potline emissions of metals. 

See CFAC BART Analysis in the docket 

(Docket ID No. EPA–HQ–OAR–2011– 

0797). Nevertheless, to ensure that the 

primary HAP metals (i.e., As and Ni) 

that are driving the allowable cancer 

risks are limited to acceptable levels of 

emissions, we are proposing facilitywide total potline emissions limits for 

As and Ni that reflect a 50 percent 

reduction in the estimated facility-wide 

secondary potline emissions of those 

metals. We are doing so pursuant to 

CAA section 112(f)(2) in order to ensure 

risks will be acceptable from the VSS2 

subcategory. Given that these reductions 

would be achieved using the same 

controls used for POM, there would be 

no added cost of control, and there 

would be risk reductions associated 

with reduced HAP metal emissions. 

Based on our analysis of available data, 

we estimated that, if this facility 

resumed operations, facility-wide 

emissions of Ni would be less than 0.14 

pounds per ton of aluminum produced 

and facility-wide emissions of As would 

be less than 0.012 pounds per ton of 

aluminum produced, using their current 

controls. Assuming wet roof scrubbers 

are installed, and assuming the wet roof 

scrubbers would achieve a 50 percent 

reduction in HAP metal emissions, and 

assuming the facility would run 3 

potlines, which is the most potlines it 

operated in the past 13 years, we 

estimate that the roof top wet scrubbers 

would be able to limit emissions of Ni 

and As from potlines to no more than 

0.07 pounds of Ni per ton of aluminum 

produced and no more than 0.006 

pounds of As per ton of aluminum 

produced, on a facility-wide basis. 

Therefore, under the authority of CAA 

section 112(f), we are proposing potline 

emission limits of 0.07 pounds of Ni per 

ton of aluminum produced and 0.006 

pounds of As per ton of aluminum 

produced. For more information 

regarding the development of these riskbased standards, see the memorandum 

titled, Development of Emissions 

Standards to Address Risks for the 

Primary Aluminum Production Source 

Category Pursuant to Section 112(f) of 

the Clean Air Act, in the docket for this 

action (Docket ID No. EPA–HQ–OAR– 

2011–0797). 

Regarding post-control risks, we 

estimate that with a POM emission limit 

that is 3 times lower than the current 

POM emission limit and with Ni and As 

emission limits that reflect a 50 percent 

reduction in potential emissions of 

those metals, that the post control risks 

would be approximately 100-in-1 

million, if the plant did reopen. 

Based on our analyses, we conclude 

that the one existing VSS2 facility, if it 

chose to reopen, could meet these limits 

with the installation of wet roof 

scrubbers on their potrooms. We note 

that it is very unlikely that any new 

Soderberg plants would be constructed 

in the U.S. because the Soderberg 

method of aluminum reduction is less 

cost effective than the prebake method 

and due to the cost that would be 

incurred to comply with the stringent 

POM limits for any new or 

reconstructed potline in the NESHAP. 

New or reconstructed sources would be 

subject to a POM limit of 0.77 pounds 

per ton of aluminum produced as 

opposed to existing sources being 

subject to a POM limit of 5.7 pounds per 

ton of aluminum produced under the 

1997 NESHAP, or 1.9 pounds per ton of 

aluminum produced if the proposed 

revised limit of 1.9 pounds per ton of 

aluminum produced in this 

supplemental proposal is adopted. 

Nevertheless, to ensure that any 

possible future Soderberg plant has 

acceptable metals emissions, we are 

proposing that any new Soderberg 

potlines would need to meet new source 

MACT limits for POM and the riskbased standards for As and Ni. 

We propose that compliance with the 

As and Ni emissions limits for existing 

VSS2 potlines and new Soderberg 

potlines will be demonstrated by annual 

performance testing along with various 

parametric monitoring on a more 

frequent basis. The proposed 

compliance testing requirements for 

POM are described in section IV.E of 

this preamble. 

3. Ample Margin of Safety Analysis 

Under the ample margin of safety 

analysis, we again consider all of the 

health factors and evaluate 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 due to emissions of HAP identified 

in our risk assessment. 

Under the ample margin of safety 

analysis, we evaluated possible options 

to reduce HAP metal and POM 

emissions from the prebake potline roof 

vents. The main option we evaluated is 

based on requiring most prebake 

facilities to install wet roof scrubbers to 

reduce secondary HAP metals emissions 

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from their potline roof vents. Under this 

option we estimate that post-control 

cancer MIR would be 40-in-1 million for 

prebake facilities (down from 70-in-1 

million). We estimate that under this 

option chronic non-cancer hazards 

would be below 1. The As maximum 

acute HQ would be reduced from 10 

down to 7. With regard to the acute As 

exposures, we estimate that about 60 

people could be exposed to 

concentrations leading to an acute HQ 

of 7, about 154 people could be exposed 

to a concentration leading to an acute 

HQ greater than 5, and that about 3,600 

people could be exposed to a 

concentration leading to an acute HQ 

greater than 1. This assessment still 

assumes, in order to reach an HQ greater 

than 1, peak emissions from the source 

category and worst-case meteorological 

conditions co-occur. We expect that this 

would happen for very few hours of the 

8,760 hours that are in a year. For HF, 

the maximum off-site HQ would be 

reduced from 3 to 2 and is at a location 

where we would not expect people to be 

for 1 hour. 

We estimate that the total capital costs 

would be at least $415 million ($46 

million per facility), annualized costs 

would be at least $133 million ($15 

million per facility), with cost 

effectiveness (CE) of $6 million per ton 

HAP metals and $130,000 per ton POM 

or higher. This option would also 

achieve 715 tpy PM2.5 reductions with 

CE of $185,000 per ton PM2.5. We 

believe these costs are substantial. 

Furthermore, based on our economic 

analysis, we project that this option 

would pose a significant economic 

burden on the companies and that 

several facilities would be at risk of 

closure under this option. The option 

would also be associated with 

potentially adverse environmental 

effects (more wastewater discharge), and 

increased energy usage (with attendant 

carbon pollution), although these are 

not the most significant factors in the 

EPA’s proposed decision. Therefore, 

given all the factors described above, we 

are not proposing this option in today’s 

action. 

In regards to the Soderberg facilities, 

we estimate that the actions proposed 

under CAA section 112(f)(2), as 

described above to address unacceptable 

risks, will reduce the MIR associated 

with allowable emissions of As, Ni and 

PAHs from 300-in-1 million to 100-in-1 

million (assuming the highly unlikely 

scenario wherein the Soderberg plant 

was to resume operation). The potential 

cancer incidence due to allowable 

emissions from this one facility will be 

reduced from 0.007 to 0.003 with a 

potential of 1 case every 330 years 

versus 1 case every 170 years, and the 

number of people estimated to 

potentially have cancer risks greater 

than 1-in-1 million will remain the same 

at 65,000 people. The chronic 

noncancer inhalation TOSHI due to 

allowable emissions will be reduced 

from 2 to 1. Based on our research and 

analysis, we did not identify any cost 

effective controls beyond those 

proposed above that would achieve 

further reduction in risk. Therefore, we 

conclude that the controls to achieve 

acceptable risks (described above) will 

also achieve an ample margin of safety. 

4. 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 

Primary 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. 

D. What are the results and proposed 

decisions based on our technology 

review? 

We updated the technology review 

conducted for the 2011 proposal and 

determined that there have been no 

developments in practices, processes 

and control technologies that would be 

considered feasible and cost effective to 

apply to this source category since the 

2011 proposal. The analysis is very 

similar to that outlined above with 

respect to potential BTF standards. 

Additional details regarding the 

technology review can be found in the 

Revised Draft Technology Review for the 

Primary Aluminum Production Plant 

Source Category, which can be found in 

the docket (Docket ID No. EPA–HQ– 

OAR–2011–0797). This same 

information underlies the EPA’s 

determination not to propose BTF limits 

and is summarized above. 

E. What other actions are we proposing? 

In addition to the proposed actions 

described above, we re-evaluated 

compliance requirements associated 

with the 2011 proposed amendments to 

determine whether we should make 

changes to those proposed amendments. 

Based on this re-evaluation, we are 

proposing the following changes to what 

was proposed in the 2011 proposal. 

1. Frequency for Testing of Prebake 

Potline POM 

The December 2011 proposal 

included a testing frequency of once 

every 5 years for POM from prebake 

potlines and provisions for estimating 

potline roof vent emissions based on 

potline stack POM emissions and 

potline stack and vent TF emissions. 

These provisions were proposed based 

on a belief that prebake potline POM 

emissions would be relatively low and 

that potline vent POM emissions would 

be difficult to determine. Based on the 

results of testing conducted in response 

to our 2013 information request, we 

determined that POM emissions from 

prebake potlines are higher than we 

expected and that methods exist for 

testing prebake vent emissions. As a 

result, we are proposing annual testing 

of POM emissions from prebake potline 

stacks and testing three times each 

semiannual period for POM emissions 

from prebake potline roof vents, with 

compliance demonstrated by summing 

emissions from these two locations. 

2. Reduced Testing Frequency for TF 

From Potlines and POM From Soderberg 

Potlines 

The NESHAP currently requires the 

owner/operator of an affected source to 

measure and record the emission rate of 

TF from potline stacks at least three 

times each year and from potline roof 

vents at least three times each month, 

unless they apply for, and receive, 

authorization to measure and record the 

roof vent TF emission rate three times 

per quarter. The NESHAP currently 

requires the owner/operator to measure 

and record the emission rate of POM 

from Soderberg potline stacks at least 

three times each year and from their 

roof vents at least three times per 

quarter. We are proposing to decrease 

the required frequencies of measuring 

and recording emission rates of TF from 

potline roof vents and POM from 

Soderberg roof vents to three times each 

semiannual period because, based on 

the consistency of previous test results 

and considering the potline work 

practices included in this supplemental 

proposal, we believe that this testing 

frequency is adequate to determine 

compliance with these emission limits. 

However, as discussed in section VI of 

this preamble, we are seeking comments 

regarding other potential testing 

frequencies. 

3. Testing, Monitoring and Reporting for 

PM, Metals and COS 

We are proposing testing, monitoring 

and reporting requirements to 

demonstrate compliance with the 

proposed emission limits for PM, Ni and 

As emissions, including the use of EPA 

Method 29 for determination of the 

emission rates of Ni and As. 

Furthermore, based on comments 

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received on the December 2011 

proposal, we are proposing the use of an 

alternate method of determination of 

sulfur in coke, for use in demonstrating 

compliance with the potline COS 

emission limit. 

4. Revisions to the Tables of Emission 

Limits for Averaging 

The current NESHAP allows 

emissions averaging across similar 

process vents. In this action, we are 

proposing revised limits applicable to 

the emission averaging to reflect the 

proposed revised and proposed 

additional emission standards described 

in section IV.A of this preamble. 

5. Alternative Emissions Limits for CoControlled New and Existing Anode 

Bake Furnaces 

We are proposing alternative emission 

limits for certain co-controlled new and 

existing anode bake furnaces to simplify 

compliance demonstration. This 

provision will allow a facility which 

uses one control device to control TF 

and POM emissions from a comingled 

exhaust from new and existing anode 

bake furnaces to comply with 

alternative production weighted average 

emission limits for those pollutants. 

These production weighted average 

emission limits are more protective than 

the emission limits that would 

otherwise apply to those sources, but 

will simplify compliance 

determinations and reduce costs for the 

sources because multiple emissions 

sources can be controlled and 

monitored at a single location. 

6. Deletion of Provisions for HSS 

Potlines 

Following the publication of the 

December 2011 proposal, the only 

existing HSS potlines were permanently 

shut down and have been dismantled. 

We are proposing to remove the 

definition and emissions standards for 

this subcategory. 

7. Startup, Shutdown, Malfunction 

In the 2011 proposal, we proposed to 

eliminate two 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 2011 

proposal, 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 CAA 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 CAA section 112 that 

directs the agency to consider 

malfunctions in determining the level 

‘‘achieved’’ by the best performing 

sources when setting emission 

standards. As the 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 CAA 

section 112 requires the agency to 

consider malfunctions as part of that 

analysis. A malfunction should not be 

treated in the same manner as the type 

of variation in performance that occurs 

during routine operations of a source. A 

malfunction is a failure of the source to 

perform in a ‘‘normal or usual manner’’ 

and no statutory language compels the 

EPA to consider such events in setting 

CAA section 112 standards. 

Further, accounting for malfunctions 

in setting emission standards would be 

difficult, if not impossible, given the 

myriad different types of malfunctions 

that can occur across all sources in the 

category and given the difficulties 

associated with predicting or accounting 

for the frequency, degree and duration 

of various malfunctions that might 

occur. Therefore, 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. Therefore, the emissions 

over a 4-day malfunction period would 

exceed the annual emissions of the 

source during normal operations. As 

this example illustrates, accounting for 

malfunctions could lead to standards 

that are not reflective of (and 

significantly less stringent than) levels 

that are achieved by a well-performing 

non-malfunctioning source. It is 

reasonable to interpret CAA section 112 

to avoid such a result. The EPA’s 

approach to malfunctions is consistent 

with CAA section 112 and is a 

reasonable interpretation of the statute. 

In the event that a source fails to 

comply with the applicable CAA section 

112(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. 

Further, to the extent the EPA files an 

enforcement action against a source for 

violation of an emission standard, 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. 

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Similarly, the presiding officer in an 

administrative proceeding can consider 

any defense raised and determine 

whether administrative penalties are 

appropriate. 

As noted above, the 2011 proposal 

included an affirmative defense to civil 

penalties for violations caused by 

malfunctions. The EPA included the 

affirmative defense in the 2011 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 

affirmative defense in the 2011 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. Recently, the 

United States Court of Appeals for the 

District of Columbia Circuit vacated an 

affirmative defense in one of the EPA’s 

CAA section 112(d) regulations. NRDC 

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

2014 U.S. App. LEXIS 7281 (vacating 

affirmative defense provisions in CAA 

section 112(d) 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 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 EPA.’’). In light of NRDC, the EPA 

is withdrawing its proposal to include a 

regulatory affirmative defense provision 

in this rulemaking. 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 United States Court of 

Appeals for the District of Columbia 

Circuit recognized, in an EPA or citizen 

enforcement action, the court has the 

discretion to consider any defense 

raised and determine whether penalties 

are appropriate. Cf. NRDC 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 the EPA administrative 

enforcement actions. 

F. What compliance dates are we 

proposing? 

In this supplementary proposal we are 

proposing changes to some of the 

compliance dates that we proposed in 

2011. Specifically, we propose that 

facilities must comply with the changes 

set out in this supplementary proposal 

which are being proposed under CAA 

section 112(d) no later than one year 

after the effective date of the final rule. 

In the 2011 proposal, we proposed that 

the facilities would be allowed up to 

three years after the effective date of the 

final rule to comply with the proposed 

changes under CAA section 112(d). 

Upon further review and analysis of 

available data, we believe that one year 

will be sufficient time to comply with 

the proposed CAA section 112(d) 

standards, which would include: 

conducting testing to demonstrate 

compliance with the proposed MACT 

standards for POM from existing 

prebake potlines and COS emissions 

from all existing potlines; implementing 

the proposed work practice standards 

for potlines, paste production plants 

and anode bake furnaces; and installing 

any necessary controls on existing pitch 

tanks. 

We also believe that one year will be 

sufficient time to conduct testing to 

demonstrate compliance with the new 

MACT standards in this supplemental 

proposal for PM emissions from existing 

potlines, paste production plants and 

anode bake furnaces, since equipment 

modifications will not be necessary. 

Finally, we propose that facilities 

must comply with the risk-based 

emission limits for POM, Ni and As 

emissions from VSS2 potlines and new 

Soderberg potlines no later than two 

years after the effective date of the final 

rule. We believe that it is appropriate to 

allow the maximum amount of time for 

compliance with these risk-based 

standards permissible pursuant to CAA 

section 112(f) (i.e., 2 years) since a 

subject facility would be required to 

install wet roof scrubbers in order to 

comply with those standards. 

V. Summary of the Revised Cost, 

Environmental and Economic Impacts 

A. What are the affected sources? 

The affected sources are new and 

existing potlines, new and existing pitch 

storage tanks, new and existing anode 

bake furnaces (except for one that is 

located at a facility that only produces 

anodes for use off-site) and new and 

existing paste plants. 

B. What are the air quality impacts? 

We estimate that the proposed lower 

VSS2 potline POM emissions limits 

would reduce POM emissions from the 

one VSS2 facility by approximately 53 

tons per year if the facility were to 

resume operation. Furthermore, we 

estimate that these proposed standards 

would also result in about 1 tpy 

reduction of HAP metals and 40 tpy 

reduction of PM2.5 if the one Soderberg 

facility reopened. 

C. What are the cost impacts? 

Under the proposed amendments, 

prebake facilities would be required to 

conduct annual POM testing on 

potlines, and all facilities would be 

required to conduct annual PM testing 

on potlines, anode bake furnaces and 

paste plants. Facilities would also be 

required to monitor 12 anode bake 

furnaces and 11 paste plants at an 

estimated cost of $129,375 per year. 

These testing costs are offset by reduced 

frequency testing of TF from all 

potlines, resulting in a reduction in 

testing costs of $2,050,000 per year. The 

total estimated cost of the rule is a 

savings of $959,000 assuming that the 

Columbia Falls Soderberg plant does not 

reopen. 

The one Soderberg facility, if it 

reopens, will be expected to install and 

operate wet roof scrubbers on their 

potrooms to comply with risk-based 

standards for POM, As and Ni at a total 

estimated capital cost of $30 million 

and annual cost of $8 million. This 

facility, if it reopens, would be also 

required to conduct annual Ni and As 

emissions tests on three potlines. Under 

this scenario, the total estimated cost of 

the rule is $7,100,000 per year. The 

memorandum, Revised Draft Cost 

Impacts for the Primary Aluminum 

Production Source Category includes a 

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42U.S. Environmental Protection Agency (U.S. 

EPA). 2009. Integrated Science Assessment for 

Particulate Matter (Final Report). EPA–600–R–08– 

139F. National Center for Environmental 

Assessment—RTP Division. Available on the 

Internet at http://cfpub.epa.gov/ncea/cfm/

recordisplay.cfm?deid=216546. 

43U.S. Environmental Protection Agency (U.S. 

EPA). 2012. Regulatory Impact Analysis for the 

Final Revisions to the National Ambient Air Quality 

Standards for Particulate Matter. Office of Air and 

Radiation, Research Triangle Park, NC. Available on 

the Internet at http://www.epa.gov/ttn/ecas/

regdata/RIAs/finalria.pdf. 

44US EPA, 2006. Integrated Risk Information 

System. http://www.epa.gov/iris/index.html. 

45US Agency for Toxic Substances and Disease 

Registry, 2013. Minimum Risk Levels (MRLs) for 

Hazardous Substances. http://www.atsdr.cdc.gov/

mrls/index.html. 

46CA Office of Environmental Health Hazard 

Assessment. Chronic Reference Exposure Levels 

Adopted by OEHHA as of December 2008. http:// 

www.oehha.ca.gov/air/chronic_rels. 

description of the assumptions used for 

this analysis and is available in the 

docket (Docket ID No. EPA–HQ–OAR– 

2011–0797). 

D. What are the economic impacts? 

We performed an economic impact 

analysis for the proposed modifications 

in this action. That analysis estimates a 

net savings for each open facility based 

on the assumption that the Columbia 

Falls Soderberg facility will not reopen. 

If Columbia Falls does reopen, the total 

estimated cost of the rule is $7,100,000 

per year. For more information, please 

refer to the memo titled, Economic 

Impact Analysis for National Emissions 

Standards for Hazardous Air Pollutants: 

Primary Aluminum Reduction Plants for 

this proposed rulemaking that is 

available in the public docket for this 

proposed rulemaking. 

E. What are the benefits? 

If the Soderberg facility were to 

resume operations, the proposed 

standards in this supplemental proposal 

would achieve an estimated reduction 

in annual HAP emissions of about 53 

tons, which would provide significant 

benefits to public health. In addition to 

the HAP reductions, which would 

ensure an ample margin of safety, we 

also estimate that this supplemental 

proposal would achieve about 230 tons 

of reductions in PM (including 40 tons 

of PM2.5) emissions as a co-benefit of the 

HAP reductions annually (again 

assuming resumption of the Soderberg 

plant operations). 

This rulemaking is not an 

‘‘economically significant regulatory 

action’’ under Executive Order 12866 

because it is not likely to have an 

annual effect on the economy of $100 

million or more. Therefore, we have not 

conducted a Regulatory Impact Analysis 

(RIA) for this rulemaking or a benefits 

analysis. While we expect that these 

avoided emissions will improve air 

quality and reduce health effects 

associated with exposure to air 

pollution associated with these 

emissions, we have not quantified or 

monetized the benefits of reducing these 

emissions for this rulemaking. This does 

not imply that there are no benefits 

associated with these emission 

reductions. We provide a qualitative 

description of benefits associated with 

reducing these pollutants below. When 

determining whether the benefits of an 

action exceed its costs, Executive Orders 

12866 and 13563 direct the agency to 

consider qualitative benefits that are 

difficult to quantify but nevertheless 

essential to consider. 

Directly emitted particles are 

precursors to secondary formation of 

fine particles (PM2.5). Controls installed 

to reduce HAP would also reduce 

ambient concentrations of PM2.5 as a cobenefit. Reducing exposure to PM2.5 is 

associated with significant human 

health benefits, including avoiding 

mortality and morbidity from 

cardiovascular and respiratory illnesses. 

Researchers have associated PM2.5

exposure with adverse health effects in 

numerous toxicological, clinical and 

epidemiological studies (U.S. EPA, 

2009).42 When adequate data and 

resources are available and an RIA is 

required, the EPA generally quantifies 

several health effects associated with 

exposure to PM2.5 (e.g., U.S. EPA, 

2012).43 These health effects include 

premature mortality for adults and 

infants, cardiovascular morbidities such 

as heart attacks, hospital admissions 

and respiratory morbidities such as 

asthma attacks, acute bronchitis, 

hospital and emergency department 

visits, work loss days, restricted activity 

days and respiratory symptoms. The 

scientific literature also suggests that 

exposure to PM2.5 is associated with 

adverse effects on birth weight, pre-term 

births, pulmonary function and other 

cardiovascular and respiratory effects 

(U.S. EPA, 2009), but the EPA has not 

quantified these impacts in its benefits 

analyses. PM2.5 also increases light 

extinction, which is an important aspect 

of visibility. 

The supplemental proposed 

rulemaking is also anticipated to reduce 

emissions of other HAP, including HAP 

metals (As, Cd, Cr (both total and 

hexavalent), Pb, Mn and Ni) and PAHs, 

assuming the Soderberg plant resumes 

operations. Some of these HAP are 

carcinogenic (e.g., As, PAHs) and some 

have effects other than cancer (e.g., 

kidney disease from Cd, respiratory and 

immunological effects from Ni). While 

we cannot quantitatively estimate the 

benefits achieved by reducing emissions 

of these HAP, we would expect benefits 

by reducing exposures to these HAP. 

More information about the health 

effects of these HAP can be found on the 

IRIS,44 ATSDR,45 and California EPA 46

Web pages. 

VI. Request for Comments 

As stated above, we are not opening 

comment on aspects of the 2011 

proposal (76 FR 76260) that have not 

changed and are not addressed in this 

supplemental proposal. Comments 

received on the 2011 proposal along 

with comments received on this 

supplemental proposal will be 

addressed in the EPA’s Response to 

Comment document and final rule 

preamble for the Primary Aluminum 

Production source category. 

We are soliciting comments on the 

revised risk assessment and technology 

review and proposed changes to the 

previously-proposed amendments. 

We are seeking comments on an 

alternative approach for demonstrating 

compliance with the emissions limits 

for potlines. Facilities face challenges 

when measuring secondary emissions 

from potlines, as these emissions are 

fugitive in nature. Some facilities 

employ a manifold system which 

captures a portion of the emissions that 

would exit the roof of the building. 

These emissions can be sampled using 

standard EPA reference methods, and 

the results can be extrapolated to 

account for the emissions from the 

entire roof. Other facilities sample the 

emissions near the roof using a series of 

elevated cassettes that contain 

removable filters. The EPA has a 

standard reference method for the 

measurement of TF using these 

cassettes, but there is not a standard 

reference method for other pollutants. 

In the 2013 CAA section 114 

information request, we requested 

facilities use filters meeting the 

requirements of EPA Method 315 in the 

cassettes and then recover and analyze 

the filters for filterable PM and POM 

using Method 315. In reviewing the 

results, we noted that there was no 

appreciable difference in the results of 

facilities that tested using the reference 

method in the manifold and facilities 

that tested using filters in cassettes. We, 

therefore, think it is reasonable to 

require facilities with manifolds to test 

at ambient conditions instead of heating 

the filter and probe. We also think it is 

reasonable to allow facilities that 

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sample in manifolds to forego the use of 

the back half of the train altogether. In 

this case, the filterable POM results 

would be a surrogate for total POM, and 

the measurement data for the cassettes 

and manifolds would be most directly 

comparable. 

We are seeking comments on the 

frequency with which the owner/

operator of affected potlines must 

measure and record emission rates of 

TF, POM and PM from roof vents. The 

frequency proposed in this action is at 

least three times each semiannual 

period. However, we are considering 

frequencies of at least three times each 

quarter or at least three times each year. 

We request that any commenter who 

would like the EPA to consider a 

different frequency include specific 

rationale and factual basis, including 

supporting data, for why a different 

frequency would be appropriate. 

VII. Submitting Data Corrections 

The site-specific emissions profiles 

used in the source category risk and 

demographic analyses and instructions 

are available for download on the RTR 

Web site at: 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–2011–0797 (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 site 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 rule have 

been submitted for approval to the OMB 

under the Paperwork Reduction Act, 44 

U.S.C. 3501 et seq. The Information 

Collection Request (ICR) document 

prepared by the EPA has been assigned 

EPA ICR number 2447.01. 

We are proposing changes to the 

paperwork requirements to the Primary 

Aluminum Production source category. 

In this supplemental proposal, we are 

proposing less frequent testing of POM 

emissions from Soderberg potlines and 

less frequent testing of TF emissions 

from all potlines. In addition, we are 

removing from this proposal the burden 

associated with the affirmative defense 

provisions included in the December 

2011 proposal. 

We estimate 13 regulated entities are 

currently subject to subpart LL 

(NESHAP for Primary Aluminum 

Reduction Plants) and will be subject to 

this action. The annual monitoring, 

reporting and recordkeeping burden for 

this collection (averaged over the first 3 

years after the effective date of the 

standards) as a result of the 

supplemental proposal revised 

amendments to subpart LL is estimated 

to be ¥$1,179,000 per year. 

This includes ¥427 labor hours per 

year at a total labor cost of ¥$32,350 

per year, and total non-labor capital and 

operation and maintenance costs of 

¥$1,212,000 per year. This estimate 

includes performance tests, 

notifications, reporting and 

recordkeeping associated with the new 

requirements for primary aluminum 

reduction plant operations. The total 

burden for the federal government 

(averaged over the first 3 years after the 

effective date of the standard) is 

estimated to be 199 hours per year at a 

total labor cost of $9,072 per year. 

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–2011–0797. 

Submit any comments related to the ICR 

to the EPA and OMB. See ADDRESSES

section at the beginning of this preamble 

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 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 

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 today’s rule 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 331312, the SBA 

small business size standard is 1,000 

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employees according to the SBA small 

business standards definitions. 

After considering the economic 

impacts of today’s action on small 

entities, I certify that this action will not 

have a significant economic impact on 

a substantial number of small entities. 

None of the companies affected by this 

rule is considered to be a small entity 

per the definition provided in this 

section. 

D. Unfunded Mandates Reform Act 

This action does not contain a federal 

mandate under the provisions of Title II 

of the Unfunded Mandates Reform Act 

of 1995 (UMRA), 2 U.S.C. 1531–1538 for 

state, local or tribal governments, or the 

private sector. The action would not 

result in expenditures of $100 million or 

more for state, local and tribal 

governments, in aggregate, or the private 

sector in any 1 year. This supplemental 

proposal imposes no enforceable duties 

on any state, local or tribal governments, 

or the private sector. Thus, this action 

is not subject to the requirements of 

sections 202 or 205 of the 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 action are 

owned or operated by state governments 

and, because no new requirements are 

being promulgated, nothing in this 

action will supersede state regulations. 

Thus, Executive Order 13132 does not 

apply to this action. 

In the spirit of Executive Order 13132, 

and consistent with EPA policy to 

promote communication between the 

EPA and state and local governments, 

the EPA specifically solicits comment 

on this proposed action 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) because it does not have 

substantial direct effects on any Indian 

tribe(s), on the relationship between the 

federal government and Indian tribes or 

on the distribution of power and 

responsibilities between the federal 

government and Indian tribes. Thus, 

Executive Order 13175 does not apply 

to this action. 

The EPA specifically solicits 

comment on this 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 the agency does not 

believe the environmental health risks 

or safety risks addressed by this action 

present a disproportionate risk to 

children. 

This rule is expected to reduce 

environmental impacts for everyone, 

including children. This action 

establishes emissions limits at the levels 

based on MACT, as required by the 

CAA. Based on our analysis, we believe 

that this rule does not have a 

disproportionate impact on children. 

The public is invited to submit 

comments or identify peer-reviewed 

studies and data that assess effects of 

early life exposure to HAP emitted from 

the Primary Aluminum Production 

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 

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. The NTTAA directs the EPA to 

provide Congress, through OMB, 

explanations when the agency decides 

not to use available and applicable VCS. 

This proposed rulemaking involves 

technical standards. The rule requires 

the use of either ASTM D3177–02 

(2007), Standard Test Methods for Total 

Sulfur in the Analysis Sample of Coal 

and Coke, or ASTM D–6376–06, Test 

Method for Determination of Trace 

Metals in Petroleum Coke by 

Wavelength Dispersive X-ray 

Fluorescence Spectroscopy. These are 

voluntary consensus methods. These 

methods can be obtained from the 

American Society for Testing and 

Materials, 100 Bar Harbor Drive, West 

Conshohocken, Pennsylvania 19428 

(telephone number (610) 832–9500). 

These methods were proposed in the 

rule because they are commonly used by 

primary aluminum production facilities 

to demonstrate compliance with sulfur 

dioxide emission limitations imposed in 

their current Title V permits. 

Under 40 CFR 63.7(f) and 40 CFR 

63.8(f) of subpart A of the General 

Provisions, a source may apply to the 

EPA for permission to use alternative 

test methods or alternative monitoring 

requirements in place of any required 

testing methods, performance 

specifications or procedures in the 

proposed rule. 

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. For 

the Primary Aluminum Production 

source category, the EPA has 

determined that the current health risks 

posed to anyone by actual emissions 

from this source category are within the 

acceptable range, and that the proposed 

rulemaking will provide and ample 

margin of safety to protect public health 

of all demographic groups. 

The EPA has determined that this 

proposed rule will not have 

disproportionately high and adverse 

human health or environmental effects 

on minority, low income or indigenous 

populations because it increases the 

level of environmental protection for all 

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72954 Federal Register / Vol. 79, No. 235 / Monday, December 8, 2014 / Proposed Rules 

affected populations without having any 

disproportionately high and adverse 

human health or environmental effects 

on any population, including any 

minority, low income or indigenous 

populations. 

These proposed standards will 

improve public health and welfare, now 

and in the future, by reducing HAP 

emissions contributing to environmental 

and human health impacts. These 

reductions in HAP associated with the 

rule are expected to benefit all 

populations. 

To examine the potential for any 

environmental justice issues that might 

be associated with the Primary 

Aluminum Production source category, 

we evaluated the distributions of HAPrelated cancer and non-cancer risks 

across different social, demographic and 

economic groups within the populations 

living near the facilities where this 

source category is located. The methods 

used to conduct demographic analyses 

for this proposed rule are described in 

the document, Risk and Technology 

Review—Analysis of Socio-Economic 

Factors for Populations Living Near 

Primary Aluminum Facilities, which 

may be found in the docket for this 

rulemaking (Docket ID No. EPA–HQ– 

OAR–2011–0797). 

In the demographics analysis, we 

focused on populations within 50 km of 

the facilities in this source category with 

emissions sources subject to the MACT 

standard. More specifically, for these 

populations, we evaluated exposures to 

HAP that could result in cancer risks of 

1-in-1 million or greater. We compared 

the percentages of particular 

demographic groups within the focused 

populations to the total percentages of 

those demographic groups nationwide. 

The results of this analysis are 

documented in the document, Risk and 

Technology Review—Analysis of SocioEconomic Factors for Populations Living 

Near Primary Aluminum Facilities, in 

the docket for this rulemaking. 

List of Subjects in 40 CFR Part 63 

Environmental protection, Air 

pollution control, Hazardous 

substances, Incorporation by reference, 

Reporting and recordkeeping 

requirements. 

Dated: November 13, 2014. 

Gina McCarthy, 

Administrator. 

For the reasons stated in the 

preamble, Title 40, chapter I, of the 

Code of Federal Regulations (CFR) is 

proposed to be amended as follows: 

PART 63—NATIONAL EMISSION 

STANDARDS FOR HAZARDOUS AIR 

POLLUTANTS FOR SOURCE 

CATEGORIES 

■ 1. The authority citation for part 63 

continues to read as follows: 

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

Subpart LL—National Emission 

Standards for Hazardous Air Pollutants 

for Primary Aluminum Reduction 

Plants 

■ 2. Section 63.840 is amended by 

revising paragraph (a) to read as follows: 

§ 63.840 Applicability. 

(a) Except as provided in paragraph 

(b) of this section, the requirements of 

this subpart apply to the owner or 

operator of each new or existing pitch 

storage tank, potline, paste production 

plant and anode bake furnace associated 

with primary aluminum production and 

located at a major source as defined in 

§ 63.2. 

* * * * * 

■ 3. Section 63.841 is amended by: 

■ a. Revising paragraphs (a)(1) and (2); 

and 

■ b. Adding paragraphs (a)(3) and (4). 

The revisions and additions read as 

follows: 

§ 63.841 Incorporation by reference. 

(a) * * * 

(1) Chapter 3, ‘‘Local Exhaust Hoods’’ 

and Chapter 5, ‘‘Exhaust System Design 

Procedure’’ of ‘‘Industrial Ventilation: A 

Manual of Recommended Practice,’’ 

American Conference of Governmental 

Industrial Hygienists, 22nd edition, 

1995, IBR approved for §§ 63.843(b) and 

63.844(b); 

(2) ASTM D 2986–95A, Standard 

Practice for Evaluation of Air Assay 

Media by the Monodisperse DOP 

(Dioctyl Phthalate) Smoke Test, IBR 

approved for section 7.1.1 of Method 

315 in appendix A to this part; 

(3) ASTM D4239–13e1, Standard Test 

Method for Sulfur in the Analysis 

Sample of Coal and Coke Using High 

Temperature Tube Furnace Combustion; 

and 

(4) ASTM D6376–10, Standard Test 

Method for Determination of Trace 

Metals in Petroleum Coke by 

Wavelength Dispersive X-Ray 

Fluorescence Spectroscopy. 

* * * * * 

■ 4. Section 63.842 is amended by: 

■ a. Adding, in alphabetical order, 

definitions of ‘‘Particulate matter (PM),’’ 

and ‘‘Startup of an anode bake furnace’’; 

■ b. Removing the definitions for 

‘‘Horizontal stud Soderberg (HSS) 

process’’ and ‘‘Vertical stud Soderberg 

one (VSS1)’’; and 

■ c. Revising the definition for ‘‘Paste 

production plant’’. 

The revisions and additions read as 

follows: 

§ 63.842 Definitions. 

* * * * * 

Particulate matter (PM) means, for the 

purposes of this subpart, emissions of 

particulate matter that serve as a 

measure of total particulate emissions 

and as a surrogate for metal hazardous 

air pollutants contained in the 

particulates, including but not limited 

to, antimony, arsenic, beryllium, 

cadmium, chromium, cobalt, lead, 

manganese, nickel and selenium. 

Paste production plant means the 

processes whereby calcined petroleum 

coke, coal tar pitch (hard or liquid) and/ 

or other materials are mixed, transferred 

and formed into briquettes or paste for 

vertical stud Soderberg (VSS) processes 

or into green anodes for a prebake 

process. This definition includes all 

operations from initial mixing to final 

forming (i.e., briquettes, paste, green 

anodes) within the paste production 

plant, including conveyors and units 

managing heated liquid pitch. 

* * * * * 

Startup of an anode bake furnace 

means the process of initiating heating 

to the anode baking furnace where all 

sections of the furnace have previously 

been at ambient temperature. The 

startup or re-start of the furnace begins 

when the heating begins. The startup 

concludes at the start of the second 

anode bake cycle if the furnace was at 

ambient temperature upon startup. The 

re-start concludes when the anode bake 

cycle resumes if the furnace was not at 

ambient temperature upon re-start. 

* * * * * 

■ 5. Section 63.843 is amended by: 

■ a. Revising paragraph (a)introductory 

text; 

■ b. Revising paragraph (a)(1)(iv); 

■ c. Removing and reserving paragraph 

(a)(1)(v); 

■ d. Revising paragraph (a)(1)(vi); 

■ e. Removing paragraph (a)(1)(vii); 

■ f. Removing and reserving paragraphs 

(a)(2)(i) and (ii); 

■ g. Revising paragraph (a)(2)(iii); 

■ h. Adding paragraphs (a)(2)(iv) 

through (vii); 

■ i. Redesignating paragraph (a)(3) as 

(a)(6); 

■ j. Adding new paragraph (a)(3)and 

paragraphs (a)(4) and (5); 

■ k. Revising paragraph (b) introductory 

text; 

■ l. Adding paragraph (b)(4); 

■ m. Revising paragraph (c) 

introductory text; 

■ n. Revising paragraphs (c)(1) and (2); 

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■ o. Adding paragraph (c)(3); and 

■ p. Adding paragraphs (d), (e) and (f). 

The revisions and additions read as 

follows: 

§ 63.843 Emission limits for existing 

sources. 

(a) Potlines. The owner or operator 

shall not discharge or cause to be 

discharged into the atmosphere any 

emissions of TF, POM, PM, nickel or 

arsenic in excess of the applicable limits 

in paragraphs (a)(1) through (a)(5) of this 

section. 

(1) * * * 

(iv) 0.8 kg/Mg (1.6 lb/ton) of 

aluminum produced for each SWPB 

potline; and 

(v) [Reserved] 

(vi) 1.35 kg/Mg (2.7 lb/ton) of 

aluminum produced for each VSS2 

potline. 

(2) * * * 

(i) [Reserved] 

(ii) [Reserved] 

(iii) 1.9 kg/Mg (3.8 lb/ton) of 

aluminum produced for each VSS2 

potline; 

(iv) 0.55 kg/Mg (1.1 lb/ton) of 

aluminum produced for each CWPB1 

prebake potline; 

(v) 6.0 kg/Mg (12 lb/ton) of aluminum 

produced for each CWPB2 prebake 

potline; 

(vi) 1.4 kg/Mg (2.7 lb/ton) of 

aluminum produced for each CWPB3 

prebake potline; and 

(vii) 9.5 kg/Mg (19 lb/ton) of 

aluminum produced for each SWPB 

prebake potline. 

(3) PM limits. Emissions of PM shall 

not exceed: 

(i) 3.6 kg/Mg (7.2 lb/ton) of aluminum 

produced for each CWPB1 potline; 

(ii) 5.5 kg/Mg (11 lb/ton) of aluminum 

produced for each CWPB2 potline; 

(iii) 10 kg/Mg (20 lb/ton) of aluminum 

produced for each CWPB3 potline; 

(iv) 2.3 kg/Mg (4.6 lb/ton) of 

aluminum produced for each SWPB 

potline; and 

(v) 13 kg/Mg (26 lb/ton) of aluminum 

produced for each VSS2 potline. 

(4) Nickel limits. Emissions of nickel 

shall not exceed 0.07 lb/ton from all 

VSS2 potlines at a primary aluminum 

reduction plant. 

(5) Arsenic limits. Emissions of 

arsenic shall not exceed 0.006 lb/ton 

from all VSS2 potlines at a primary 

aluminum reduction plant. 

(6) Change in subcategory. Any 

potline, other than a reconstructed 

potline, that is changed such that its 

applicable subcategory also changes 

shall meet the applicable emission limit 

in this subpart for the original 

subcategory or the new subcategory, 

whichever is more stringent. 

(b) Paste production plants. The 

owner or operator shall install, operate 

and maintain equipment to capture and 

control POM and PM emissions from 

each paste production plant. 

* * * * * 

(4) PM limits. Emissions of PM shall 

not exceed 0.041 kg/Mg (0.082 lb/ton) of 

green anode. 

(c) Anode bake furnaces. The owner 

or operator shall not discharge or cause 

to be discharged into the atmosphere 

any emissions of TF, POM or PM in 

excess of the limits in paragraphs (c)(1) 

through (3) of this section. 

(1) TF limit. Emissions of TF shall not 

exceed 0.10 kg/Mg (0.20 lb/ton) of green 

anode; 

(2) POM limit. Emissions of POM 

shall not exceed 0.09 kg/Mg (0.18 lb/

ton) of green anode; and 

(3) PM limit. Emissions of PM shall 

not exceed 0.034 kg/Mg (0.068 lb/ton) of 

green anode. 

(d) Pitch storage tanks. Each pitch 

storage tank shall be equipped with an 

emission control system designed and 

operated to reduce inlet emissions of 

POM by 95 percent or greater. 

(e) COS limit. Emissions of COS must 

not exceed 1.95 kg/Mg (3.9 lb/ton) of 

aluminum produced for each potline. 

(f) At all times, the owner or operator 

must operate and maintain any affected 

source, including associated air 

pollution control equipment and 

monitoring equipment, in a manner 

consistent with safety and good air 

pollution control practices for 

minimizing emissions. Determination of 

whether such operation and 

maintenance procedures are being used 

will be based on information available 

to the Administrator which may 

include, but is not limited to, 

monitoring results, review of operation 

and maintenance procedures, review of 

operation and maintenance records and 

inspection of the source. 

■ 6. Section 63.844 is amended by: 

■ a. Revising paragraph (a) introductory 

text; 

■ b. Revising paragraph (a)(2); 

■ c. Adding paragraphs (a)(3) through 

(5); 

■ d. Revising paragraph (b) introductory 

text; 

■ e. Adding paragraphs (b)(1) and (2); 

■ f. Revising paragraph (c) introductory 

text; 

■ g. Revising paragraphs (c)(1) and (2); 

■ h. Adding paragraph (c)(3); and 

■ i. Adding paragraphs (e) and (f). 

The revisions and additions read as 

follows: 

§ 63.844 Emission limits for new or 

reconstructed sources. 

(a) Potlines. The owner or operator 

shall not discharge or cause to be 

discharged into the atmosphere any 

emissions of TF, POM, PM, nickel or 

arsenic in excess of the applicable limits 

in paragraphs (a)(1) through (a)(5) of this 

section. 

* * * * * 

(2) POM limit. Emissions of POM from 

potlines must not exceed 0.39 kg/Mg 

(0.77 lb/ton) of aluminum produced. 

(3) PM limit. Emissions of PM from 

potlines must not exceed 2.3 kg/Mg (4.6 

lb/ton) of aluminum produced. 

(4) Nickel limits. Emissions of nickel 

shall not exceed 0.07 lb/ton from all 

Soderberg potlines at a primary 

aluminum reduction plant. 

(5) Arsenic limits. Emissions of 

arsenic shall not exceed 0.006 lb/ton 

from all Soderberg potlines at a primary 

aluminum reduction plant. 

(b) Paste production plants. 

(1) The owner or operator shall meet 

the requirements in § 63.843(b)(1) 

through (3) for existing paste production 

plants and shall not discharge or cause 

to be discharged into the atmosphere 

any emissions of PM in excess of the 

limit in paragraph (b)(2) of this section. 

(2) Emissions of PM shall not exceed 

0.0028 kg/Mg (0.0056 lb/ton) of green 

anode. 

(c) Anode bake furnaces. The owner 

or operator shall not discharge or cause 

to be discharged into the atmosphere 

any emissions of TF, PM or POM in 

excess of the limits in paragraphs (c)(1) 

through (3) of this section. 

(1) TF limit. Emissions of TF shall not 

exceed 0.01 kg/Mg (0.02 lb/ton) of green 

anode; 

(2) POM limit. Emissions of POM 

shall not exceed 0.025 kg/Mg (0.05 lb/ 

ton) of green anode; and 

(3) PM limit. Emissions of PM shall 

not exceed 0.018 kg/Mg (0.036 lb/ton) of 

green anode. 

* * * * * 

(e) COS limit. Emissions of COS must 

not exceed 3.1 lb/ton of aluminum 

produced for each potline. 

(f) At all times, the owner or operator 

must operate and maintain any affected 

source, including associated air 

pollution control equipment and 

monitoring equipment, in a manner 

consistent with safety and good air 

pollution control practices for 

minimizing emissions. Determination of 

whether such operation and 

maintenance procedures are being used 

will be based on information available 

to the Administrator which may 

include, but is not limited to, 

monitoring results, review of operation 

and maintenance procedures, review of 

operation and maintenance records and 

inspection of the source. 

■ 7. Section 63.846 is amended by: 

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72956 Federal Register / Vol. 79, No. 235 / Monday, December 8, 2014 / Proposed Rules 

■ a. Revising paragraph (b) introductory 

text; 

■ b. Revising paragraphs (b)(1) through 

(3); 

■ c. Revising paragraph (c) introductory 

text; 

■ d. Revising paragraphs (c)(1) and (2); 

■ e. Revising paragraphs (d)(2)(ii) 

through (iv); 

■ f. Revising paragraphs (d)(4)(i) 

through (iii); and 

■ g. Removing (d)(4)(iv). 

The revisions read as follows: 

§ 63.846 Emission averaging. 

* * * * * 

(b) Potlines. The owner or operator 

may average emissions from potlines 

and demonstrate compliance with the 

limits in Tables 1 through 3 of this 

subpart using the procedures in 

paragraphs (b)(1) through (3) of this 

section. 

(1) Annual average emissions of TF 

shall not exceed the applicable emission 

limit in Table 1 of this subpart. The 

emission rate shall be calculated based 

on the total primary and secondary 

emissions from all potlines over the 

period divided by the quantity of 

aluminum produced during the period, 

from all potlines comprising the 

averaging group. To determine 

compliance with the applicable 

emission limit in Table 1 of this subpart 

for TF emissions, the owner or operator 

shall determine the average emissions 

(in lb/ton) from each potline from at 

least three runs per potline 

semiannually for TF secondary 

emissions and at least three runs per 

potline primary control system each 

year using the procedures and methods 

in §§ 63.847 and 63.849. The owner or 

operator shall combine the results of 

secondary TF average emissions with 

the TF results for the primary control 

system and divide total emissions by 

total aluminum production. 

(2) Annual average emissions of POM 

shall not exceed the applicable emission 

limit in Table 2 of this subpart. The 

emission rate shall be calculated based 

on the total primary and secondary 

emissions from all potlines over the 

period divided by the quantity of 

aluminum produced during the period, 

from all potlines comprising the 

averaging group. To determine 

compliance with the applicable 

emission limit in Table 2 of this subpart 

for POM emissions, the owner or 

operator shall determine the average 

emissions (in lb/ton) from each potline 

from at least three runs per potline 

semiannually for POM secondary 

emissions and at least three runs per 

potline primary control system each 

year for POM primary emissions using 

the procedures and methods in 

§§ 63.847 and 63.849. The owner or 

operator shall combine the results of 

secondary POM average emissions with 

the POM results for the primary control 

system and divide total emissions by 

total aluminum production. 

(3) Annual average emissions of PM 

shall not exceed the applicable emission 

limit in Table 3 of this subpart. The 

emission rate shall be calculated based 

on the total primary and secondary 

emissions from all potlines over the 

period divided by the quantity of 

aluminum produced during the period, 

from all potlines comprising the 

averaging group. To determine 

compliance with the applicable 

emission limit in Table 3 of this subpart 

for PM emissions, the owner or operator 

shall determine the average emissions 

(in lb/ton) from each potline from at 

least three runs per potline 

semiannually for PM secondary 

emissions and at least three runs per 

potline primary control system each 

year for PM primary emissions using the 

procedures and methods in §§ 63.847 

and 63.849. The owner or operator shall 

combine the results of secondary PM 

average emissions with the PM results 

for the primary control system and 

divide total emissions by total 

aluminum production. 

(c) Anode bake furnaces. The owner 

or operator may average TF emissions 

from anode bake furnaces and 

demonstrate compliance with the limits 

in Table 4 of this subpart using the 

procedures in paragraphs (c)(1) and (2) 

of this section. The owner or operator 

also may average POM emissions from 

anode bake furnaces and demonstrate 

compliance with the limits in Table 4 of 

this subpart using the procedures in 

paragraphs (c)(1) and (2) of this section. 

The owner or operator also may average 

PM emissions from anode bake furnaces 

and demonstrate compliance with the 

limits in Table 4 of this subpart using 

the procedures in paragraphs (c)(1) and 

(2) of this section. 

(1) Annual emissions of TF, POM 

and/or PM from a given number of 

anode bake furnaces making up each 

averaging group shall not exceed the 

applicable emission limit in Table 4 of 

this subpart in any one year; and 

(2) To determine compliance with the 

applicable emission limit in Table 4 of 

this subpart for anode bake furnaces, the 

owner or operator shall determine TF, 

POM and/or PM emissions from the 

control device for each furnace at least 

once each year using the procedures and 

methods in §§ 63.847 and 63.849. 

(d) * * * 

(2) * * * 

(ii) The assigned TF, POM or PM 

emission limit for each averaging group 

of potlines or anode bake furnaces; 

(iii) The specific control technologies 

or pollution prevention measures to be 

used for each emission source in the 

averaging group and the date of its 

installation or application. If the 

pollution prevention measures reduce 

or eliminate emissions from multiple 

sources, the owner or operator must 

identify each source; 

(iv) The test plan for the measurement 

of TF, POM or PM emissions in 

accordance with the requirements in 

§ 63.847(b) and (k); 

* * * * * 

(4) * * * 

(i) Any averaging between emissions 

of differing pollutants or between 

differing sources. Emission averaging 

shall not be allowed between TF, POM 

and PM, and emission averaging shall 

not be allowed between potlines and 

anode bake furnaces; 

(ii) The inclusion of any emission 

source other than an existing potline or 

existing anode bake furnace or the 

inclusion of any potline or anode bake 

furnace not subject to the same 

operating permit; or 

(iii) The inclusion of any potline or 

anode bake furnace while it is shut 

down, in the emission calculations. 

* * * * * 

■ 8. Section 63.847 is amended by: 

■ a. Revising paragraph (a) introductory 

text; 

■ b. Revising paragraphs (a)(1) and (2); 

■ c. Removing and reserving paragraph 

(a)(3); 

■ d. Removing and reserving paragraph 

(b)(6); 

■ e. Revising paragraphs (c)(1) through 

(3); 

■ f. Revising paragraph (d) introductory 

text; 

■ g. Revising paragraph (d)(1); 

■ h. Removing and reserving paragraph 

(d)(2); 

■ i. Revising paragraph (d)(4); 

■ j. Adding paragraphs (d)(5) and (6); 

■ k. Revising paragraphs (e)(1) and (4); 

■ l. Adding paragraphs (e)(8) and (e)(9); 

■ m. Revising paragraph (f); 

■ n. Revising paragraph (g) introductory 

text; 

■ o. Revising paragraphs (g)(2)(ii) and 

(iv); 

■ p. Adding and reserving paragraph (i); 

and 

■ q. Adding paragraphs (j), (k), (l) and 

(m). 

The revisions and additions read as 

follows: 

§ 63.847 Compliance provisions. 

(a) Compliance dates. The owner 

operator of a primary aluminum 

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reduction plant must comply with the 

requirements of this subpart by the 

applicable compliance date in 

paragraph (a)(1), (a)(2), (a)(3) or (a)(4) of 

this section: 

(1) Except as noted in paragraph (2) of 

this section, the compliance date for an 

owner or operator of an existing plant or 

source subject to the provisions of this 

subpart is October 7, 1999. 

(2) The compliance dates for existing 

plants and sources are: 

(i) [DATE OF PUBLICATION OF 

FINAL RULE] for the malfunction 

provisions of §§ 63.850(d)(2) and 

(e)(4)(xvi) and (xvii) and the electronic 

reporting provisions of §§ 63.850(c) and 

(f) which became effective [DATE OF 

PUBLICATION OF FINAL RULE]. 

(ii) [DATE 1 YEAR AFTER DATE OF 

PUBLICATION OF FINAL RULE] for 

prebake potlines subject to emission 

limits in §§ 63.843(a)(2)(iv) through 

(vii); for potlines subject to the work 

practice standards in § 63.854(a), the 

COS emission limit provisions of 

§ 63.843(e) and the PM emissions limit 

provisions of §§ 63.843(a)(3)(i) through 

(v); for anode bake furnaces subject to 

the startup practices in § 63.847(l) and 

PM emission limits in § 63.843(c)(3); for 

compliance with the pitch storage tank 

POM limit provisions of § 63.843(d); for 

paste production plants subject to the 

startup practices in § 63.847(m) and PM 

emission limits in § 63.843(b)(4) which 

became effective [DATE OF 

PUBLICATION OF FINAL RULE]. 

(iii) [DATE 2 YEARS AFTER DATE 

OF PUBLICATION OF FINAL RULE] for 

Soderberg potlines subject to emission 

limits in § 63.843(a)(2)(iii), (a)(4) and 

(a)(5) which became effective [DATE OF 

PUBLICATION OF FINAL RULE]. 

(3) [Reserved] 

* * * * * 

(b) * * * 

(6) [Reserved] 

* * * * * 

(c) * * * 

(1) During the first month following 

the compliance date for an existing 

potline (or potroom group), anode bake 

furnace or pitch storage tank. 

(2) By the 180th day following startup 

for a potline or potroom group for which 

the owner or operator elects to conduct 

an initial performance test. The 180-day 

period starts when the first pot in a 

potline or potroom group is energized. 

(3) By the 180th day following startup 

for a potline or potroom group that was 

shut down at the time compliance 

would have otherwise been required 

and is subsequently restarted. The 180- 

day period starts when the first pot in 

a potline or potroom group is energized. 

(d) Performance test requirements. 

The initial performance test and all 

subsequent performance tests must be 

conducted in accordance with the 

requirements of the general provisions 

in subpart A of this part, the approved 

test plan and the procedures in this 

section. Performance tests must be 

conducted under such conditions as the 

Administrator specifies to the owner or 

operator based on representative 

performance of the affected source for 

the period being tested. Upon request, 

the owner or operator must make 

available to the Administrator such 

records as may be necessary to 

determine the conditions of 

performance tests. 

(1) TF, POM and PM emissions from 

potlines. For each potline, the owner or 

operator shall measure and record the 

emission rates of TF, POM and PM 

exiting the outlet of the primary control 

system for each potline and the rate of 

secondary emissions exiting through 

each roof monitor, or for a plant with 

roof scrubbers, exiting through the 

scrubbers. Using the equation in 

paragraph (e)(1) of this section, the 

owner or operator shall compute and 

record the average of at least three runs 

semiannually for secondary emissions 

and at least three runs each year for the 

primary control system to determine 

compliance with the applicable 

emission limit. Compliance is 

demonstrated when the emission rate of 

TF is equal to or less than the applicable 

emission limit in § 63.843, § 63.844, or 

§ 63.846. 

(2) [Reserved] 

* * * * * 

(4) TF, POM and PM emissions from 

anode bake furnaces. For each anode 

bake furnace, the owner or operator 

shall measure and record the emission 

rate of TF, POM and PM exiting the 

exhaust stacks(s) of the primary 

emission control system for each anode 

bake furnace. In accordance with 

paragraphs (e)(3), (4) and (8) of this 

section, the owner or operator shall 

compute and record the average of at 

least three runs each year to determine 

compliance with the applicable 

emission limits for TF, POM and PM. 

Compliance is demonstrated when the 

emission rates of TF, POM and PM are 

equal to or less than the applicable TF, 

POM and PM emission limits in 

§ 63.843, § 63.844, or § 63.846. 

(5) Nickel Emissions from VSS2 

Potlines and new Soderberg potlines. (i) 

For each VSS2 potline, and for each 

new Soderberg potline, the owner or 

operator must measure and record the 

emission rate of nickel exiting the 

primary emission control system and 

the rate of secondary emissions of nickel 

exiting through each roof monitor, or for 

a plant with roof scrubbers, exiting 

through the scrubbers. Using the 

procedure in paragraph (e)(10) of this 

section, the owner or operator must 

compute and record the average of at 

least three runs each year for secondary 

emissions and at least three runs each 

year for primary emissions. 

(ii) Compliance is demonstrated when 

the emissions of nickel are equal to or 

less than the applicable emission limit 

in § 63.843(a)(4) or § 63.844(a)(4). 

(6) Arsenic Emissions from VSS2 

Potlines and from new Soderberg 

potlines. (i) For each VSS2 potline, and 

for each new Soderberg potline, the 

owner or operator must measure and 

record the emission rate of arsenic 

exiting the primary emission control 

system and the rate of secondary 

emissions of arsenic exiting through 

each roof monitor, or for a plant with 

roof scrubbers, exiting through the 

scrubbers. Using the procedure in 

paragraph (e)(11) of this section, the 

owner or operator must compute and 

record the average of at least three runs 

each year for secondary emissions and 

at least three runs each year for primary 

emissions. 

(ii) Compliance is demonstrated when 

the emissions of arsenic are equal to or 

less than the applicable emission limit 

in § 63.843(a)(5) or § 63.844(a)(5). 

(e) * * * 

(1) Compute the emission rate (Ep) of 

TF, POM or PM from each potline using 

Equation 1: 


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Where: 

Ep = emission rate of TF, POM or PM from 

a potline, kg/Mg (lb/ton); 

Cs1 = concentration of TF, POM or PM from 

the primary control system, mg/dscm 

(mg/dscf); 

Qsd = volumetric flow rate of effluent gas 

corresponding to the appropriate 

subscript location, dscm/hr (dscf/hr); 

Cs2 = concentration of TF, POM or PM as 

measured for roof monitor emissions, 

mg/dscm (mg/dscf); 

P = aluminum production rate, Mg/hr (ton/ 

hr); 

K = conversion factor, 106 mg/kg (453,600 

mg/lb); 

1 = subscript for primary control system 

effluent gas; and 

2 = subscript for secondary control system or 

roof monitor effluent gas. 

* * * * * 

(4) Compute the emission rate of POM 

from each anode bake furnace using 

Equation 2, 

Where: 

Eb = emission rate of POM, kg/mg (lb/ton) of 

green anodes produced; and 

Cs = concentration of POM, mg/dscm (mg/

dscf). 

* * * * * 

(8) Compute the emission rate of PM 

from each anode bake furnace using 

Equation 2, 

Where: 

Eb = emission rate of PM, kg/mg (lb/ton) of 

green anodes produced; and 

Cs = concentration of PM, mg/dscm (mg/

dscf). 

(9) Compute the emission rate (EPMpp) 

of PM from each paste production plant 

using Equation 3, 

Where: 

EPMpp = emission rate of PM, kg/mg (lb/ton) 

of green anodes produced; 

Cs = concentration of PM, mg/dscm (mg/

dscf); 

Qsd = volumetric flow rate of effluent gas, 

dscm/hr (dscf/hr); 

Pb = quantity of green anode material placed 

in the anode bake furnace, mg/hr (ton/

hr); and 

K = conversion factor, 106 mg/kg (453,600 

mg/lb). 

(f) Paste production plants. (1) Initial 

compliance with the POM standards for 

existing and new paste production 

plants in §§ 63.843(b) and 63.844(b) will 

be demonstrated through site 

inspection(s) and review of site records 

by the applicable regulatory authority. 

(2) For each paste production plant, 

the owner or operator shall measure and 

record the emission rate of PM exiting 

the exhaust stacks(s) of the primary 

emission control system. Using the 

equations in paragraph (e)(9) of this 

section, the owner or operator shall 

compute and record the average of at 

least three runs each year to determine 

compliance with the applicable 

emission limits for PM. Compliance 

with the PM standards for existing and 

new paste production plants is 

demonstrated when the PM emission 

rates are less than or equal to the 

applicable PM emission limits in 

§§ 63.843(b)(4) and 63.844(b)(2). 

(g) Pitch storage tanks. The owner or 

operator must demonstrate initial 

compliance with the standard for pitch 

storage tanks in §§ 63.843(d) and 

63.844(d) by preparing a design 

evaluation or by conducting a 

performance test. The owner or operator 

must submit for approval by the 

regulatory authority the information 

specified in paragraph (g)(1) of this 

section, along with the information 

specified in paragraph (g)(2) of this 

section where a design evaluation is 

performed or the information specified 

in paragraph (g)(3) of this section where 

a performance test is conducted. 

* * * * * 

(2) * * * 

(ii) If an enclosed combustion device 

with a minimum residence time of 0.5 

seconds and a minimum temperature of 

760 degrees C (1,400 degrees F) is used 

to meet the emission reduction 

requirement specified in § 83.843(d) and 

§ 83.844(d), documentation that those 

conditions exist is sufficient to meet the 

requirements of § 83.843(d) and 

§ 83.844(d); 

* * * * * 

(iv) If the pitch storage tank is vented 

to the emission control system installed 

for control of emissions from the paste 

production plant pursuant to § 63.843(b) 

or § 63.844(b)(1), documentation of 

compliance with the requirements of 

§ 63.843(b) is sufficient to meet the 

requirements of § 63.843(b) or 

§ 63.844(d); 

* * * * * 

(i) [Reserved] 

(j) COS emissions. The owner operator 

of each plant must calculate, for each 

potline, the emission rate of COS for 

each calendar month of operation using 

Equation 5: 

Where: 

ECOS = the emission rate of COS during the 

calendar month in pounds per ton of 

aluminum produced; 

K = factor accounting for molecular weights 

and conversion of sulfur to carbonyl 

sulfide = 234; 

Y = the tons of anode consumed in the 

potline during the calendar month; 

Z = the tons of aluminum produced by the 

potline during the calendar month; and 

S = the weighted average fraction of sulfur in 

the anode coke consumed in the 

production of aluminum during the 

calendar month (e.g., if the weighted 

average sulfur content of the anode coke 

consumed during the calendar month 

was 2.5 percent, then S = 0.025). The 

weight of anode coke used during the 

month of each different concentration of 

sulfur is used to calculate the overall 

weighted average fraction of sulfur. 

Compliance is demonstrated if the 

calculated value of ECOS is less than the 

applicable standard for COS emissions 

in §§ 63.843(e) and 63.844(e). 

(k) Startup of potlines. The owner or 

operator must develop a written startup 

plan as described in § 63.854 that 

contains specific procedures to be 

followed during startup periods of 

potline(s). Compliance with the 

applicable standards in § 63.854 will be 

demonstrated through site inspection(s) 

and review of site records by the 

regulatory authority. 

(l) Startup of anode bake furnaces. If 

you own or operate a new or existing 

anode bake furnace, you must develop 

a written startup plan as described in 

paragraphs (l)(1) through (4) of this 


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section. Compliance with the startup 

plan will be demonstrated through site 

inspection(s) and review of site records 

by the regulatory authority. The written 

startup plan must contain specific 

procedures to be followed during 

startup periods of anode bake furnaces, 

including the following: 

(1) A requirement to develop an 

anode bake furnace startup schedule. 

(2) Records of time, date, duration of 

anode bake furnace startup and any 

nonroutine actions taken during startup 

of the furnaces. 

(3) A requirement that the associated 

emission control system should be 

operating within normal parametric 

limits prior to startup of the anode bake 

furnace. 

(4) A requirement to shut down the 

anode bake furnaces immediately if the 

associated emission control system is off 

line at any time during startup. The 

anode bake furnace restart may resume 

once the associated emission control 

system is back on line and operating 

within normal parametric limits. 

(m) Startup of paste production 

plants. If you own or operate a new or 

existing paste production plant, you 

must develop a written startup plan as 

described in paragraphs (m)(1) through 

(3) of this section. Compliance with the 

startup plan will be demonstrated 

through site inspection(s) and review of 

site records by the regulatory authority. 

The written startup plan must contain 

specific procedures to be followed 

during startup periods of paste 

production plants, including the 

following: 

(1) Records of time, date, duration of 

paste production plant startup and any 

nonroutine actions taken during startup 

of the paste production plants. 

(2) A requirement that the associated 

emission control system should be 

operating within normal parametric 

limits prior to startup of the paste 

production plant. 

(3) A requirement to shut down the 

paste production plant immediately if 

the associated emission control system 

is off line at any time during startup. 

The paste production plant restart may 

resume once the associated emission 

control system is back on line and 

operating within normal parametric 

limits. 

■ 9. Section 63.848 is amended by: 

■ a. Revising paragraphs (a) and (b); 

■ b. Removing and reserving paragraph 

(e); 

■ c. Adding paragraphs (f)(6) and (7); 

and 

■ d. Adding paragraphs (n), (o) and (p). 

The revisions and additions read as 

follows: 

§ 63.848 Emission monitoring 

requirements. 

(a) TF and PM emissions from 

potlines. Using the procedures in 

§ 63.847 and in the approved test plan, 

the owner or operator shall monitor 

emissions of TF and PM from each 

potline by conducting annual 

performance tests on the primary 

control system and semiannual 

performance tests on the secondary 

emissions. The owner or operator shall 

compute and record the average from at 

least three runs for secondary emissions 

and the average from at least three runs 

for the primary control system to 

determine compliance with the 

applicable emission limit. The owner or 

operator must include all valid runs in 

the semiannual average. The duration of 

each run for secondary emissions must 

represent a complete operating cycle. 

Potline emissions shall be recorded as 

the sum of the average of at least three 

runs from the primary control system 

and the average of at least three runs 

from the roof monitor or secondary 

control device. 

(b) POM emissions from potlines. 

Using the procedures in § 63.847 and in 

the approved test plan, the owner or 

operator must monitor emissions of 

POM from each potline stack annually 

and secondary potline POM emissions 

semiannually. The owner or operator 

must compute and record the 

semiannual average from at least three 

runs per year for secondary emissions 

and at least three runs per year for the 

primary control systems to determine 

compliance with the applicable 

emission limit. The owner or operator 

must include all valid runs in the 

semiannual average. The duration of 

each run for secondary emissions must 

represent a complete operating cycle. 

The primary control system must be 

sampled over an 8-hour period, unless 

site-specific factors dictate an 

alternative sampling time subject to the 

approval of the regulatory authority. 

Potline emissions shall be recorded as 

the sum of the average of at least three 

runs from the primary control system 

and the average of at least three runs 

from the roof monitor or secondary 

control device. 

* * * * * 

(e) [Reserved] 

(f) * * * 

(6) For emission sources with fabric 

filters that choose to demonstrate 

continuous compliance through bag leak 

detection systems you must install a bag 

leak detection system according to the 

requirements in paragraph (o) of this 

section, and you must set your operating 

limit such that the sum of the durations 

of bag leak detection system alarms does 

not exceed 5 percent of the process 

operating time during a 6-month period. 

(7) If you choose to demonstrate 

continuous compliance through a 

particulate matter CEMS, you must 

determine continuous compliance 

averaged on a rolling 30 operating day 

basis. All valid hours of data from 30 

successive operating days shall be 

included in the average. 

* * * * * 

(n) PM emissions from anode bake 

furnaces and paste production plants. 

Using the procedures in § 63.847 and in 

the approved test plan, the owner or 

operator shall monitor PM emissions 

from each anode bake furnace and paste 

production plant on an annual basis. 

The owner or operator shall compute 

and record the annual average of PM 

emissions from at least three runs to 

determine compliance with the 

applicable emission limits. The owner 

or operator must include all valid runs 

in the annual average. 

(o) Bag leak detection system. For 

each baghouse used to control PM 

emissions, you must install, operate and 

maintain a bag leak detection system 

according to paragraphs (o)(1) through 

(3) of this section, unless a system 

meeting the requirements of paragraph 

(p) of this section, for a CEMS and 

continuous emissions rate monitoring 

system, is installed for monitoring the 

concentration of particulate matter. 

(1) You must develop and implement 

written procedures for baghouse 

maintenance that include, at a 

minimum, a preventative maintenance 

schedule that is consistent with the 

baghouse manufacturer’s instructions 

for routine and long-term maintenance. 

(2) Each bag leak detection system 

must meet the specifications and 

requirements in paragraphs (o)(2)(i) 

through (viii) of this section. 

(i) The bag leak detection system must 

be certified by the manufacturer to be 

capable of detecting PM emissions at 

concentrations of 1.0 milligram per dry 

standard cubic meter (0.00044 grains 

per actual cubic foot) or less. 

(ii) The bag leak detection system 

sensor must provide output of relative 

PM loadings. 

(iii) The bag leak detection system 

must be equipped with an alarm system 

that will alarm when an increase in 

relative particulate loadings is detected 

over a preset level. 

(iv) You must install, calibrate, 

operate and maintain the bag leak 

detection system according to the 

manufacturer’s written specifications 

and recommendations. 

(v) The initial adjustment of the 

system must, at a minimum, consist of 

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establishing the baseline output by 

adjusting the sensitivity (range) and the 

averaging period of the device and 

establishing the alarm set points and the 

alarm delay time. 

(vi) Following initial adjustment, you 

must not adjust the sensitivity or range, 

averaging period, alarm set points, or 

alarm delay time, except in accordance 

with the procedures developed under 

paragraph (o)(1) of this section. You 

cannot increase the sensitivity by more 

than 100 percent or decrease the 

sensitivity by more than 50 percent over 

a 365-day period unless such 

adjustment follows a complete baghouse 

inspection that demonstrates that the 

baghouse is in good operating condition. 

(vii) You must install the bag leak 

detector downstream of the baghouse. 

(viii) Where multiple detectors are 

required, the system’s instrumentation 

and alarm may be shared among 

detectors. 

(3) You must include in the written 

procedures required by paragraph (o)(1) 

of this section a corrective action plan 

that specifies the procedures to be 

followed in the case of a bag leak 

detection system alarm. The corrective 

action plan must include, at a 

minimum, the procedures that you will 

use to determine and record the time 

and cause of the alarm as well as the 

corrective actions taken to minimize 

emissions as specified in paragraphs 

(o)(3)(i) and (ii) of this section. 

(i) The procedures used to determine 

the cause of the alarm must be initiated 

within 30 minutes of the alarm. 

(ii) The cause of the alarm must be 

alleviated by taking the necessary 

corrective action(s) that may include, 

but not be limited to, those listed in 

paragraphs (o)(3)(ii)(A) through (F) of 

this section. 

(A) Inspecting the baghouse for air 

leaks, torn or broken filter elements, or 

any other malfunction that may cause 

an increase in emissions. 

(B) Sealing off defective bags or filter 

media. 

(C) Replacing defective bags or filter 

media, or otherwise repairing the 

control device. 

(D) Sealing off a defective baghouse 

compartment. 

(E) Cleaning the bag leak detection 

system probe, or otherwise repairing the 

bag leak detection system. 

(F) Shutting down the process 

producing the particulate emissions. 

(p) Particulate Matter CEMS. If you 

are using a CEMS to measure particulate 

matter emissions to meet requirements 

of this subpart, you must install, certify, 

operate and maintain the particulate 

matter CEMS as specified in paragraphs 

(p)(1) through (4) of this section. 

(1) You must conduct a performance 

evaluation of the PM CEMS according to 

the applicable requirements of § 60.13, 

and Performance Specification 11 at 40 

CFR part 60, Appendix B of this 

chapter. 

(2) During each PM correlation testing 

run of the CEMS required by 

Performance Specification 11 at 40 CFR 

part 60, Appendix B of this chapter, 

collect data concurrently (or within a 

30- to 60-minute period) by both the 

CEMS and by conducting performance 

tests using Method 5, 5D or 5I at 40 CFR 

part 60, Appendix A–3 or Method 17 at 

40 CFR part 60, Appendix A–6 of this 

chapter. 

(3) Perform quarterly accuracy 

determinations and daily calibration 

drift tests in accordance with Procedure 

2 at 40 CFR part 60, Appendix F of this 

chapter. Relative Response Audits must 

be performed annually and Response 

Correlation Audits must be performed 

every three years. 

(4) Within 60 days after the date of 

completing each CEMS response audit 

or performance test conducted to 

demonstrate compliance with this 

subpart, you must submit the response 

audit data as specified in § 63.850(c) 

and the results of the performance test 

as specified in § 63.850(b). 

■ 10. Section 63.849 is amended by: 

■ a. Revising paragraphs (a)(6) and (7); 

■ b. Adding paragraphs (a)(8) through 

(11); and 

■ c. Adding paragraph (f). 

The revisions and additions read as 

follows: 

§ 63.849 Test methods and procedures. 

(a) * * * 

(6) Method 315 in appendix A to this 

part or an approved alternative method 

for the concentration of POM where 

stack or duct emissions are sampled; 

(7) Method 315 in appendix A to this 

part and Method 14A in appendix A to 

part 60 of this chapter or an approved 

alternative method for the concentration 

of POM where emissions are sampled 

from roof monitors not employing wet 

roof scrubbers. Method 315 need not be 

set up as required in the method. 

Instead, replace the Method 14A 

monitor cassette filter with the filter 

specified by Method 315. Recover and 

analyze the filter according to Method 

315; 

(8) Method 5 in appendix A to part 60 

of this chapter or an approved 

alternative method for the concentration 

of PM where stack or duct emissions are 

sampled; 

(9) Method 17 and Method 14A in 

appendix A to part 60 of this chapter or 

an approved alternative method for the 

concentration of PM where emissions 

are sampled from roof monitors not 

employing wet roof scrubbers. Method 

17 need not be set up as required in the 

method. Instead, replace the Method 

14A monitor cassette filter with the 

filter specified by Method 17. Recover 

and analyze the filter according to 

Method 17; 

(10) Method 29 in appendix A to part 

60 of this chapter or an approved 

alternative method for the concentration 

of nickel and arsenic where stack or 

duct emissions are sampled; and 

(11) Method 29 and Method 14A in 

appendix A to part 60 of this chapter or 

an approved alternative method for the 

concentration of nickel and arsenic 

where emissions are sampled from roof 

monitors not employing wet roof 

scrubbers. Method 29 need not be set up 

as required in the method. Instead, 

replace the Method 14A monitor 

cassette filter with the filter specified by 

Method 29. Recover and analyze the 

filter according to Method 29. 

* * * * * 

(f) The owner or operator must use 

either ASTM D4239–13e1 or ASTM 

D6376–10 for determination of the 

sulfur content in anode coke shipments 

to determine compliance with the 

applicable emission limit for COS 

emissions. 

■ 11. Section 63.850 is amended by: 

■ a. Revising paragraphs (b), (c) and (d); 

■ b. Removing and reserving paragraph 

(e)(4)(iii); 

■ c. Revising paragraphs (e)(4)(xiv) and 

(xv); 

■ d. Adding paragraphs (e)(4)(xvi) and 

(xvii); and 

■ e. Adding paragraph (f). 

The revisions and additions read as 

follows: 

§ 63.850 Notification, reporting and 

recordkeeping requirements. 

* * * * * 

(b) Performance test reports. Within 

60 days after the date of completing 

each performance test required by this 

subpart, the owner or operator shall 

submit the results of the performance 

test following the procedure specified in 

either paragraph (b)(1) or (b)(2) of this 

section. 

(1) For data collected using test 

methods supported by the EPA’s 

Electronic Reporting Tool (ERT) as 

listed on the EPA’s ERT Web site 

(http://www.epa.gov/ttn/chief/ert/

index.html) at the time of the test, the 

owner or operator shall submit the 

results of the performance test to the 

EPA via the Compliance and Emissions 

Data Reporting Interface (CEDRI). 

(CEDRI can be accessed through the 

EPA’s Central Data Exchange (CDX) 

(http://cdx.epa.gov/epa_home.asp).) 

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Performance test data shall be submitted 

in a file format generated through the 

use of the EPA’s ERT. Instead of 

submitting performance test data in a 

file format generated through the use of 

the EPA’s ERT, you may submit an 

alternate electronic file format 

consistent with the extensible markup 

language (XML) schema listed on the 

EPA’s ERT Web site, once the XML 

schema is available. Owners or 

operators who claim that some of the 

performance test information being 

submitted is confidential business 

information (CBI) shall submit a 

complete file generated through the use 

of the EPA’s ERT (or an alternate 

electronic file consistent with the XML 

schema listed on the EPA’s ERT Web 

site once the XML schema is available), 

including information claimed to be 

CBI, on a compact disc, flash drive, or 

other commonly used electronic storage 

media to the EPA. The electronic media 

shall be clearly marked as CBI and 

mailed to U.S. EPA/OAQPS/CORE CBI 

Office, Attention: Group Leader, 

Measurement Policy Group, MD C404– 

02, 4930 Old Page Road, Durham, NC 

27703. The same ERT or alternate file 

with the CBI omitted shall be submitted 

to the EPA via the EPA’s CDX as 

described earlier in this paragraph. 

(2) For data collected using test 

methods that are not supported by the 

EPA’s ERT as listed on the EPA’s ERT 

Web site at the time of the test, the 

owner or operator shall submit the 

results of the performance test to the 

Administrator at the appropriate 

address listed in § 63.13. 

(c) Performance evaluation reports. 

Within 60 days after the date of 

completing each CEMS performance 

evaluation, submit the results of the 

performance evaluation following the 

procedure specified in either paragraph 

(c)(1) or (2) of this section. 

(1) For performance evaluations of 

continuous monitoring systems 

measuring pollutants that are supported 

by the EPA’s ERT as listed on the EPA’s 

ERT Web site, you must submit the 

results of the performance evaluation to 

the EPA via the CEDRI. (CEDRI can be 

accessed through the EPA’s CDX.) 

Performance evaluation data must be 

submitted in a file format generated 

through the use of the EPA’s ERT. 

Instead of submitting performance test 

data in a file format generated through 

the use of the EPA’s ERT, you may 

submit an alternate electronic file 

format consistent with the XML schema 

listed on the EPA’s ERT Web site, once 

the XML schema is available. If you 

claim that some of the performance 

evaluation information being submitted 

is CBI, you must submit a complete file 

generated through the use of the EPA’s 

ERT (or an alternate electronic file 

consistent with the XML schema listed 

on the EPA’s ERT Web site once the 

XML schema is available), including 

information claimed to be CBI, on a 

compact disc, flash drive or other 

commonly used electronic storage 

media to the EPA. The electronic media 

must be clearly marked as CBI and 

mailed to U.S. EPA/OAQPS/CORE CBI 

Office, Attention: Group Leader, 

Measurement Policy Group, MD C404– 

02, 4930 Old Page Road, Durham, NC 

27703. The same ERT or alternate file 

with the CBI omitted must be submitted 

to the EPA via the EPA’s CDX as 

described earlier in this paragraph. 

(2) For any performance evaluations 

of continuous monitoring systems 

measuring pollutants that are not 

supported by the EPA’s ERT as listed on 

the EPA’s ERT Web site, submit the 

results of the performance evaluation to 

the Administrator at the appropriate 

address listed in § 63.13. 

(d) Reporting. In addition to the 

information required under § 63.10 of 

the General Provisions, the owner or 

operator must provide semiannual 

reports containing the information 

specified in paragraphs (d)(1) and (2) of 

this section to the Administrator or 

designated authority. 

(1) Excess emissions report. As 

required by § 63.10(e)(3), the owner or 

operator must submit a report (or a 

summary report) if measured emissions 

are in excess of the applicable standard. 

The report must contain the information 

specified in § 63.10(e)(3)(v) and be 

submitted semiannually unless 

quarterly reports are required as a result 

of excess emissions. 

(2) If there was a malfunction during 

the reporting period, the owner or 

operator must submit a report that 

includes the number, duration and a 

brief description for each type of 

malfunction which occurred during the 

reporting period and which caused or 

may have caused any applicable 

emission limitation to be exceeded. The 

report must also include a description of 

actions taken by an owner or operator 

during a malfunction of an affected 

source to minimize emissions in 

accordance with §§ 63.843(f) and 

63.844(f), including actions taken to 

correct a malfunction. 

(e) * * * 

(4) * * * 

(iii) [Reserved] 

* * * * * 

(xiv) Records documenting any POM 

data that are invalidated due to the 

installation and startup of a cathode; 

(xv) Records documenting the portion 

of TF that is measured as particulate 

matter and the portion that is measured 

as gaseous when the particulate and 

gaseous fractions are quantified 

separately using an approved test 

method; 

(xvi) Records of the occurrence and 

duration of each malfunction of 

operation (i.e., process equipment) or 

the air pollution control equipment and 

monitoring equipment; and 

(xvii) Records of actions taken during 

periods of malfunction to minimize 

emissions in accordance with §§ 63.843 

and 63.844, including corrective actions 

to restore malfunctioning process and 

air pollution control and monitoring 

equipment to its normal or usual 

manner of operation. 

(f) All reports required by this subpart 

not subject to the requirements in 

paragraph (b) of this section must be 

sent to the Administrator at the 

appropriate address listed in § 63.13. If 

acceptable to both the Administrator 

and the owner or operator of a source, 

these reports may be submitted on 

electronic media. The Administrator 

retains the right to require submittal of 

reports subject to paragraph (b) of this 

section in paper format. 

■ 12. Section 63.854 is added to read as 

follows: 

§ 63.854 Work Practice Standards for 

Potlines. 

(a) Periods of operation other than 

startup. If you own or operate a new or 

existing primary aluminum reduction 

affected source, you must comply with 

the requirements of paragraphs (a)(1) 

through (4) of this section during 

periods of operation other than startup. 

(1) Ensure the potline scrubbers and 

exhaust fans are operational at all times. 

(2) Ensure that the primary capture 

and control system is operating at all 

times. 

(3) Keep pots covered as much as 

practicable to include but not limited to 

minimizing the removal of covers or 

panels of the pots on which work is 

being performed. 

(4) Inspect potlines daily and perform 

the work practices specified in 

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

section. 

(i) Identify unstable pots as soon as 

practicable but in no case more than 12 

hours from the time the pot became 

unstable; 

(ii) Reduce cell temperatures to as low 

as practicable, and follow the written 

operating plan described in paragraph 

(b)(4) of this section if the cell 

temperature exceeds the specified high 

temperature limit; and 

(iii) Reseal pot crusts that have been 

broken as often and as soon as 

practicable. 

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72962 Federal Register / Vol. 79, No. 235 / Monday, December 8, 2014 / Proposed Rules 

(b) Periods of startup. If you own or 

operate a new or existing primary 

aluminum reduction affected source, 

you must comply with the requirements 

of paragraphs (a)(1) through (4) and 

(b)(1) through (4) of this section during 

periods of startup for each affected 

potline. 

(1) Develop a potline startup schedule 

before starting up the potline. 

(2) Keep records of the number of pots 

started each day. 

(3) Inspect potlines daily and adjust 

pot parameters to their optimum levels, 

as specified in the operating plan 

described in paragraph (b)(4) of this 

section, including, but not limited to: 

Alumina addition rate, exhaust air flow 

rate, cell voltage, feeding level, anode 

current and liquid and solid bath levels. 

(4) Prepare a written operating plan to 

minimize emissions during startup to 

include, but not limited to, the 

requirements in (b)(1) through (3) of this 

section. The operating plan must 

include a specified high temperature 

limit for pots that will trigger corrective 

action. 

■ 13. Section 63.855 is added to read as 

follows: 

§ 63.855 Alternative Emissions Limits for 

Co-controlled New and Existing Anode 

Bake Furnaces. 

(a) Applicability. The owner or 

operator of a new anode bake furnace 

meeting the criteria of paragraphs (a)(1) 

and (2) of this section may demonstrate 

compliance with alternative TF and 

POM emission limits according to the 

procedures of this section. 

(1) The new anode bake furnace must 

have been permitted to operate prior to 

May 1, 1998; and 

(2) The new anode bake furnace must 

share a common control device with one 

or more existing anode bake furnaces. 

(b) TF emission limit. (1) Prior to the 

date on which each TF emission test is 

required to be conducted, the owner or 

operator must determine the applicable 

TF emission limit using Equation 6–A, 

Where: 

LTFC = Combined emission limit for TF, lb/ 

ton green anode material placed in the 

bake furnace; 

LTFE = TF limit for emission averaging for the 

total number of new and existing anode 

bake furnaces from Table 4 to this 

subpart; 

PE = Mass of green anode placed in existing 

anode bake furnaces in the twelve 

months preceding the compliance test, 

ton/year; and 

PN = Mass of green anode placed in new 

anode bake furnaces in the twelve 

months preceding the compliance test, 

ton/year. 

(2) The owner or operator of a new 

anode bake furnace that is controlled by 

a control device that also controls 

emissions of TF from one or more 

existing anode bake furnaces must not 

discharge, or cause to be discharged into 

the atmosphere, any emissions of TF in 

excess of the emission limits established 

in paragraph (b)(1) of this section. 

(c) POM emission limits. (1) Prior to 

the date on which each POM emission 

test is required to be conducted, the 

owner or operator must determine the 

applicable POM emission limit using 

Equation 6–B, 

Where: 

LPOMC = Combined emission limit for POM, 

lb/ton green anode material placed in the 

bake furnace. 

(2) The owner or operator of a new 

anode bake furnace that is controlled by 

a control device that also controls 

emissions of POM from one or more 

existing anode bake furnaces must not 

discharge, or cause to be discharged into 

the atmosphere, any emissions of TF in 

excess of the emission limits established 

in paragraph (c)(1) of this section. 

■ 14. Table 1 to Subpart LL of Part 63— 

Potline TF Limits for Emission 

Averaging is revised to read as follows: 

TABLE 1 TO SUBPART LL OF PART 63—POTLINE TF LIMITS FOR EMISSION AVERAGING

Type 

Monthly TF limit (lb/ton) [for given number of potlines] 

2 lines 3 lines 4 lines 5 lines 6 lines 7 lines 8 lines 

CWPB1 ........................ 1.7 1.6 1.5 1.5 1.4 1.4 1.4 

CWPB2 ........................ 2.9 2.8 2.7 2.7 2.6 2.6 2.6 

CWPB3 ........................ 2.3 2.2 2.2 2.1 2.1 2.1 2.1 

SWPB ........................... 1.4 1.3 1.3 1.2 1.2 1.2 1.2 

VSS2 ............................ 2.6 2.5 2.5 2.4 2.4 2.4 2.4 

■ 15. Table 2 to Subpart LL of Part 63— 

Potline POM Limits for Emission 

Averaging is revised to read as follows: 

TABLE 2 TO SUBPART LL OF PART 63—POTLINE POM LIMITS FOR EMISSION AVERAGING

Type 

Quarterly POM limit (lb/ton) [for given number of potlines] 

2 lines 3 lines 4 lines 5 lines 6 lines 7 lines 8 lines 

CWPB1 ........................ 1 0.9 0.9 0.9 0.8 0.8 0.8 

CWPB2 ........................ 11.6 11.2 10.8 10.8 10.4 10.4 10.4 

CWPB3 ........................ 2.5 2.4 2.4 2.3 2.3 2.3 2.3 


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Federal Register / Vol. 79, No. 235 / Monday, December 8, 2014 / Proposed Rules 72963 

TABLE 2 TO SUBPART LL OF PART 63—POTLINE POM LIMITS FOR EMISSION AVERAGING—Continued 

Type 

Quarterly POM limit (lb/ton) [for given number of potlines] 

2 lines 3 lines 4 lines 5 lines 6 lines 7 lines 8 lines 

SWPB ........................... 16.6 15.4 15.4 14.3 14.3 14.3 14.3 

VSS2 ............................ 3.3 3.1 3.0 2.9 2.9 2.8 2.7 

■ 16. Table 3 to subpart LL is 

redesignated as Table 4 to Subpart LL of 

Part 63—Anode Bake Furnace Limits for 

Emission Averaging and revised to read 

as follows: 

TABLE 4 TO SUBPART LL OF PART 63—ANODE BAKE FURNACE LIMITS FOR EMISSION AVERAGING

Number of furnaces 

Emission limit (lb/ton of anode) 

TF POM PM 

2 ................................................................................................................................................. 0 .11 0.17 0.037 

3 ................................................................................................................................................. 0 .09 0.17 0.031 

4 ................................................................................................................................................. 0 .077 0.17 0.026 

5 ................................................................................................................................................. 0 .07 0.17 0.024 

■ 17. New Table 3 to Subpart LL of Part 

63—Potline PM Limits for Emission 

Averaging is added to read as follows: 

TABLE 3 TO SUBPART LL OF PART 63—POTLINE PM LIMITS FOR EMISSION AVERAGING

Type 

Monthly PM limit (lb/ton) [for given number of potlines] 

2 lines 3 lines 4 lines 5 lines 6 lines 7 lines 8 lines 

CWPB1 ...................... 5 .9 5.6 5.2 5.2 4.9 4.9 4.9 

CWPB2 ...................... 10 .6 10.3 9.9 9.9 9.5 9.5 9.5 

CWPB3 ...................... 18 .4 17.6 17.6 16.8 16.8 16.8 16.8 

SWPB ......................... 4 3.7 3.7 3.5 3.5 3.5 3.5 

VSS2 .......................... 25 24.1 24.1 23.1 23.1 23.1 23.1 

■ 18. Appendix A to Subpart LL of Part 

63—Applicability of General Provisions 

is revised to read as follows: 

APPENDIX A TO SUBPART LL OF PART 63—APPLICABILITY OF GENERAL PROVISIONS

[40 CFR Part 63, Subpart A] 

Reference 

section(s) . . . Requirement Applies to subpart LL Comment 

63.1(a)(1) through (4) .. General Applicability ....................................... Yes.

63.5(a)(5) ..................... ......................................................................... Yes.

63.1(a)(6) ..................... ......................................................................... Yes.

63.1(a)(7) through (9) .. ......................................................................... No ............................... [Reserved]. 

63.1(a)(10) through 

(12).

......................................................................... Yes. 

63.1(b)(1) through (3) .. Initial Applicability Determination .................... Yes ............................. (b)(2) Reserved.

63.1(c)(1) ..................... Applicability after standard Established .......... Yes.

63.1(c)(2) ..................... ......................................................................... Yes.

63.1(c)(3) and (4) ........ ......................................................................... No ............................... [Reserved]. 

63.1(c)(5) ..................... ......................................................................... Yes.

63.1(d) ......................... ......................................................................... Yes ............................. [Reserved]. 

63.1(e) ......................... Applicability of Permit Program ...................... Yes. 

63.2 .............................. Definitions ....................................................... Yes. 

63.3 .............................. Units and Abbreviations .................................. Yes .............................

63.4(a)(1) and (2) ........ Prohibited activities ......................................... Yes. 

63.4(a)(3) through (5) .. ......................................................................... No ............................... [Reserved]. 

63.4(b) and (c) ............. Circumvention/Severability .............................. Yes. 

63.5(a)(5) ..................... Construction/Reconstruction Applicability ....... Yes. 

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72964 Federal Register / Vol. 79, No. 235 / Monday, December 8, 2014 / Proposed Rules 

APPENDIX A TO SUBPART LL OF PART 63—APPLICABILITY OF GENERAL PROVISIONS—Continued 

[40 CFR Part 63, Subpart A] 

Reference 

section(s) . . . Requirement Applies to subpart LL Comment 

63.5(b)(1) ..................... Existing, New, Reconstructed Sources Requirements.Yes. 

63.5(b)(2) ..................... ......................................................................... No ............................... [Reserved]. 

63.5(b)(3) and (4) ........ ......................................................................... Yes. 

63.5(b)(5) ..................... ......................................................................... No ............................... [Reserved]. 

63.5(b)(6) ..................... ......................................................................... Yes. 

63.5(c) ......................... ......................................................................... No ............................... [Reserved]. 

63.5(d) ......................... Application for Approval of Construction/Reconstruction.Yes. 

63.5(e) ......................... Approval of Construction/Reconstruction ....... Yes. 

63.5(f) .......................... Approval of Construction/Reconstruction 

Based on State Review.

Yes .............................

63.6(a) ......................... Compliance with Standards and Maintenance 

Applicability.

Yes .............................

63.6(b)(1) through (5) .. New and Reconstructed Source Dates .......... Yes. 

63.6(b)(6) and (7) ........ ......................................................................... No ............................... [Reserved]. 

63.6(c)(1) ..................... Existing Source Dates .................................... Yes. 

63.6(c)(2) ..................... ......................................................................... Yes. 

63.6(c)(3) and (4) ........ ......................................................................... No ............................... [Reserved]. 

63.6(c)(5) ..................... ......................................................................... Yes. 

63.6(d) ......................... ......................................................................... No ............................... [Reserved]. 

63.6(e)(1)(i) .................. ......................................................................... No ............................... See §§ 63.843(f) and 63.844(f) for general 

duty requirement. 

63.6(e)(1)(ii) ................. ......................................................................... No ...............................

63.6(e)(1)(iii) ................ ......................................................................... Yes. 

63.6(e)(2) ..................... ......................................................................... No ............................... [Reserved]. 

63.6(e)(3) ..................... Startup, Shutdown and Malfunction Plan ....... No. 

63.6(f)(1) ...................... Compliance with Emissions Standards .......... No. 

63.6(f)(1) and (2) ......... Methods/Finding of Compliance ..................... Yes. 

63.6(g) ......................... Alternative Standard ....................................... Yes. 

63.6(h) ......................... Compliance with Opacity/VE Standards ......... Only in § 63.845 ......... Opacity standards applicable only when incorporating the NSPS requirements under 

§ 63.845 

63.6(i)(1) through (14) Extension of Compliance ................................ Yes. 

63.6(i)(15) .................... ......................................................................... No. [Reserved]. 

63.6(i)(16) .................... ......................................................................... Yes. 

63.6(j) .......................... Exemption from Compliance ........................... Yes. 

63.7(a) ......................... Performance Test Requirements Applicability Yes. 

63.7(b) ......................... Notification ...................................................... Yes. 

63.7(c) ......................... Quality Assurance/Test Plan .......................... Yes. 

63.7(d) ......................... Testing facilities .............................................. Yes. 

63.7(e)(1) ..................... Conduct of Tests ............................................. No ............................... See § 63.847(d) 

63.7(e)(2) through (4) .. ......................................................................... Yes. 

63.7(f),(g), (h) .............. Alternative Test Method .................................. Yes. 

63.8(a) ......................... Monitoring Requirements Applicability ............ Yes. 

63.8(b) ......................... Conduct of Monitoring ..................................... Yes. 

63.8(c)(1)(i) .................. ......................................................................... No ............................... See §§ 63.843(f) and 63.844(f) for general 

duty requirement. 

63.8(c)(1)(ii) ................. ......................................................................... Yes. 

63.8(c)(1)(iii) ................ ......................................................................... No. 

63.8(c)(2) through 

(d)(2).

......................................................................... Yes. 

63.8(d)(3) ..................... ......................................................................... Yes, except for last 

sentence. 

63.8(e) through (g) ...... ......................................................................... Yes. 

63.9(a),(b),(c),(e),(g),(h)

(1) through (3), (h)(5) 

and (6), (i) and (j).

......................................................................... Yes. 

63.9(a) ......................... Notification Requirements Applicability ........... Yes. 

63.9(b) ......................... Initial Notifications ........................................... Yes. 

63.9(c) ......................... Request for Compliance Extension ................ Yes. 

63.9(d) ......................... New Source Notification for Special Compliance Requirements.Yes. 

63.9(e) ......................... Notification of Performance Test .................... Yes. 

63.9(f) .......................... Notification of VE/Opacity Test ....................... Yes. 

63.9(g) ......................... Additional CMS Notifications .......................... Yes. 

63.9(h)(1) through (3) .. Notification of Compliance Status ................... Yes. 

63.9(h)(4) ..................... ......................................................................... No ............................... [Reserved]. 

63.9(h)(5) and (6) ........ ......................................................................... Yes. 

63.9(i) .......................... Adjustment of Deadlines ................................. Yes. 

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Federal Register / Vol. 79, No. 235 / Monday, December 8, 2014 / Proposed Rules 72965 

APPENDIX A TO SUBPART LL OF PART 63—APPLICABILITY OF GENERAL PROVISIONS—Continued 

[40 CFR Part 63, Subpart A] 

Reference 

section(s) . . . Requirement Applies to subpart LL Comment 

63.9(j) .......................... Change in Previous Information ..................... Yes. 

63.10(a) ....................... Recordkeeping/Reporting Applicability ........... Yes. 

63.10(b)(1) ................... General Recordkeeping Requirements .......... Yes. 

63.10(b)(2)(i) ................ No. 

63.10(b)(2)(ii) ............... ......................................................................... No ............................... See §§ 63.850(e)(4)(xvi) and (xvii) for recordkeeping of occurrence and duration of malfunctions and recordkeeping of actions 

taken during malfunction. 

63.10(b)(2)(iii) .............. ......................................................................... Yes. 

63.10(b)(2)(iv) and (v) ......................................................................... No. 

63.10(b)(2)(vi) through 

(xiv).

......................................................................... Yes. 

63.(10)(b)(3) ................ ......................................................................... Yes. 

63.10(c)(1) through (9) ......................................................................... Yes. 

63.10(c)(10) and (11) .. ......................................................................... No ............................... See §§ 63.850(e)(4)(xvi) and (xvii)for recordkeeping of malfunctions. 

63.10(c)(12) through 

(14).

......................................................................... Yes.

63.10(c)(15) ................. ......................................................................... No.

63.10(d)(1) through (4) General Reporting Requirements ................... Yes.

63.10(d)(5) ................... Startup-Shutdown and Malfunction Reports ... No ............................... See § 63.850(d)(2) for reporting of malfunctions. 

63.10(e) and (f) ........... Additional CMS Reports and Recordkeeping/

Reporting Waiver.

Yes.

63.11 ............................ Control Device/work practices requirements 

Applicability.

No.

63.12 ............................ State Authority and Delegations ..................... Yes.

63.13 ............................ Addresses ....................................................... Yes.

63.14 ............................ Incorporation by Reference ............................ Yes.

63.15 ............................ Information Availability/Confidentiality ............ Yes.

63.16 ............................ Performance Track Provisions ........................ No.

[FR Doc. 2014–27499 Filed 12–5–14; 8:45 am] 

BILLING CODE 6560–50–P 

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