76260 Federal Register / Vol. 76, No. 234 / Tuesday, December 6, 2011 / Proposed Rules 

ENVIRONMENTAL PROTECTION 

40 CFR Part 63 

[EPA–HQ–OAR–2011–0797; FRL–9491–3] 

RIN 2060–AQ92 

National Emissions Standards for 

Hazardous Air Pollutants: Primary 

Aluminum Reduction Plants 

AGENCY: Environmental Protection 

Agency (EPA). 

ACTION: Proposed rule. 

SUMMARY: The EPA is proposing 

amendments to the national emissions 

standards for hazardous air pollutants 

for Primary Aluminum Reduction Plants 

to address the results of the residual risk 

and technology review that the EPA is 

required to conduct by the Clean Air 

Act. If finalized, these proposed 

amendments would address previously 

unregulated emissions (i.e., carbonyl 

sulfide (COS) emissions from new and 

existing potlines and polycyclic organic 

matter (POM) emissions from new and 

existing prebake potlines and existing 

pitch storage tanks); remove the vertical 

stud Soderberg one (VSS1) potline 

subcategory; reduce the MACT limits for 

POM emissions from horizontal stud 

Soderberg (HSS) and VSS2 potlines; 

eliminate the startup, shutdown and 

malfunction exemption in accordance 

with recent actions by the United States 

Court of Appeals for the District of 

Columbia Circuit; add provisions for 

facilities to avail themselves of an 

affirmative defense in the event of a 

malfunction under certain conditions; 

and make certain technical and editorial 

changes. The proposed emissions limits 

for POM and COS are based on 

maximum achievable control 

technology (MACT). While the proposed 

modifications would result in some 

reduction in actual emissions of POM 

from existing pitch storage tanks, reduce 

the potential emissions of POM from 

Soderberg potlines, and prevent 

increases in emissions of COS and 

sulfur dioxide, the health risks posed by 

actual emissions from this source 

category are currently within the 

acceptable range and would not be 

reduced appreciably by the proposed 

modifications. 

DATES: Comments must be received on 

or before January 20, 2012. Under the 

Paperwork Reduction Act, comments on 

the information collection provisions 

are best assured of receiving full 

consideration if the Office of 

Management and Budget (OMB) 

receives a copy of your comments on or 

before January 5, 2012. 

Public Hearing. If anyone contacts the 

EPA requesting to speak at a public 

hearing by December 16, 2011, a public 

hearing will be held on December 21, 

2011. 

ADDRESSES: Submit your comments, 

identified by Docket ID Number EPA– 

HQ–OAR–2011–0797, by one of the 

following methods: 

• http://www.regulations.gov: Follow 

the on-line instructions for submitting 

comments. 

• Email: a-and-r-docket@epa.gov, 

Attention Docket ID Number EPA–HQ– 

OAR–2011–0797. 

• Fax: (202) 566–9744, Attention 

Docket ID Number EPA–HQ–OAR– 

2011–0797. 

• Mail: U.S. Postal Service, send 

comments to: EPA Docket Center, EPA 

West (Air Docket), Attention Docket ID 

Number EPA–HQ–OAR–2011–0797, 

U.S. Environmental Protection Agency, 

Mail Code: 2822T, 1200 Pennsylvania 

Ave. NW., Washington, DC 20460. 

Please include a total of two copies. In 

addition, please mail a copy of your 

comments on the information collection 

provisions to the Office of Information 

and Regulatory Affairs, Office of 

Management and Budget (OMB), Attn: 

Desk Officer for EPA, 725 17th Street, 

NW., Washington, DC 20503. 

• Hand Delivery: U.S. Environmental 

Protection Agency, EPA West (Air 

Docket), Room 3334, 1301 Constitution 

Ave. NW., Washington, DC 20004, 

Attention Docket ID Number EPA–HQ– 

OAR–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 Number 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 on-line at http:// 

www.regulations.gov, including any 

personal information provided, unless 

the comment includes information 

claimed to be confidential business 

information (CBI) or other information 

whose disclosure is restricted by statute. 

Do not submit information that you 

consider to be CBI or otherwise 

protected through http:// 

www.regulations.gov or email. The 

http://www.regulations.gov Web site is 

an ‘‘anonymous access’’ system, which 

means the EPA will not know your 

identity or contact information unless 

you provide it in the body of your 

comment. If you send an email 

comment directly to the EPA without 

going through http:// 

www.regulations.gov, your email 

address will be automatically captured 

and included as part of the comment 

that is placed in the public docket and 

made available on the Internet. If you 

submit an electronic comment, the EPA 

recommends that you include your 

name and other contact information in 

the body of your comment and with any 

disk or CD–ROM you submit. If the EPA 

cannot read your comment due to 

technical difficulties and cannot contact 

you for clarification, the EPA may not 

be able to consider your comment. 

Electronic files should avoid the use of 

special characters, any form of 

encryption, and be free of any defects or 

viruses. For additional information 

about the EPA’s public docket, visit the 

EPA Docket Center homepage at http:// 

www.epa.gov/epahome/dockets.htm. 

Docket. The EPA has established a 

docket for this rulemaking under Docket 

ID Number EPA–HQ–OAR–2011–0797. 

All documents in the docket are listed 

in the http://www.regulations.gov index. 

Although listed in the index, some 

information is not publicly available, 

e.g., CBI or other information whose 

disclosure is restricted by statute. 

Certain other material, such as 

copyrighted material, is not placed on 

the Internet and will be publicly 

available only in hard copy. Publicly 

available docket materials are available 

either electronically in http:// 

www.regulations.gov or in hard copy at 

the EPA Docket Center, EPA West, 

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 EPA Docket Center is 

(202) 566–1742. 

Public Hearing. If a public hearing is 

held, it will begin at 10 a.m. on 

December 21, 2011 and will be held at 

the EPA’s campus in Research Triangle 

Park, North Carolina, or at an alternate 

facility nearby. Persons interested in 

presenting oral testimony or inquiring 

as to whether a public hearing is to be 

held should contact Ms. Virginia Hunt, 

Office of Air Quality Planning and 

Standards, Sector Policies and Programs 

Division, (D243–02), U.S. 

Environmental Protection Agency, 

Research Triangle Park, North Carolina 

27711; telephone number: (919) 541– 

0832. 

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, U.S. Environmental 


jlentini on DSK4TPTVN1PROD with PROPOSALS3
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Protection Agency, Research Triangle 

Park, North Carolina 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 Dr. Michael 

Stewart, Office of Air Quality Planning 

and Standards, Health and 

Environmental Impacts Division, Air 

Toxics Assessment Group (C504–06), 

U.S. Environmental Protection Agency, 

Research Triangle Park, NC 27711; 

telephone number: (919) 541–7524; fax 

number: (919) 541–0840; and email 

address: stewart.michael@epa.gov. For 

information about the applicability of 

the proposed or current national 

emission standards for hazardous air 

pollutants (NESHAP) for primary 

aluminum reduction plants to a 

particular entity, contact the appropriate 

person listed in Table 1 of this 

preamble. 

TABLE 1—LIST OF EPA CONTACTS FOR THE NESHAP ADDRESSED IN THIS PROPOSED ACTION

NESHAP for: OECA Contact 1 OAQPS Contact 2

Primary Aluminum Reduction Plants .................. Patrick Yellin, 

(202) 564–2970, yellin.patrick@epa.gov 

David Putney, 

(919) 541–2016, putney.david@epa.gov 

1EPA Office of Enforcement and Compliance Assurance. 

2EPA Office of Air Quality Planning and Standards. 

SUPPLEMENTARY INFORMATION: 

Preamble Acronyms and Abbreviations 

Several acronyms and terms used to 

describe industrial processes, data 

inventories, and risk modeling are 

included in this preamble. While this 

may not be an exhaustive list, the 

following terms and acronyms are 

defined here for reference: 

ADAF age-dependent adjustment factors 

AEGL acute exposure guideline levels 

AERMOD air dispersion model used by the 

HEM–3 model 

AMOS ample margin of safety 

ANPRM advance notice of proposed 

rulemaking 

ATSDR Agency for Toxic Substances and 

Disease Registry 

BACT best available control technology 

BLDS bag leak detection system 

CAA Clean Air Act 

CBI Confidential Business Information 

CEMS continuous emissions monitoring 

system 

CFR Code of Federal Regulations 

COS carbonyl sulfide 

CTE central tendency exposure 

EJ environmental justice 

EPA Environmental Protection Agency 

ERPG Emergency Response Planning 

Guidelines 

ERT Electronic Reporting Tool 

HAP hazardous air pollutants 

HEM–3 Human Exposure Model, Version 3 

HEPA high efficiency particulate air 

HHRAP Human Health Risk Assessment 

Protocols 

HI Hazard Index 

HQ Hazard Quotient 

ICR information collection request 

IRIS Integrated Risk Information System 

Km kilometer 

LAER lowest achievable emissions rate 

lb/yr pounds per year 

MACT maximum achievable control 

technology 

MACT Code Code within the NEI used to 

identify processes included in a source 

category 

MDL method detection level 

mg/acm milligrams per actual cubic meter 

mg/dscm milligrams per dry standard cubic 

meter 

mg/m3 milligrams per cubic meter 

MIR maximum individual risk 

MRL minimum risk level 

NAC/AEGL Committee National Advisory 

Committee for Acute Exposure Guideline 

Levels for Hazardous Substances 

NAICS North American Industry 

Classification System 

NAS National Academy of Sciences 

NATA National Air Toxics Assessment 

NEI National Emissions Inventory 

NESHAP National Emissions Standards for 

Hazardous Air Pollutants 

NOAEL no observed adverse effects level 

NRC National Research Council 

NTTAA National Technology Transfer and 

Advancement Act 

O&M operation and maintenance 

OAQPS Office of Air Quality Planning and 

Standards 

ODW Office of Drinking Water 

OECA Office of Enforcement and 

Compliance Assurance 

OHEA Office of Health and Environmental 

Assessment 

OMB Office of Management and Budget 

PB–HAP hazardous air pollutants known to 

be persistent and bio-accumulative in the 

environment 

PM particulate matter 

POM polycyclic organic matter 

ppmv parts per million volume 

RACT reasonably available control 

technology 

RBLC RACT/BACT/LAER Clearinghouse 

REL reference exposure level 

RFA Regulatory Flexibility Act 

RfC reference concentration 

RfD reference dose 

RIA Regulatory Impact Analysis 

RTR residual risk and technology review 

SAB Science Advisory Board 

SBA Small Business Administration 

SCC Source Classification Codes 

SOP standard operating procedures 

SSM startup, shutdown, and malfunction 

TEQ toxic equivalency quotient 

TOSHI target organ-specific hazard index 

TPY tons per year 

TRIM Total Risk Integrated Modeling 

System 

TTN Technology Transfer Network 

UF uncertainty factor 

mg/m 3 microgram per cubic meter 

UL upper limit 

UMRA Unfunded Mandates Reform Act 

UPL upper predictive limit 

URE unit risk estimate 

WHO World Health Organization 

WWW worldwide web 

Organization of this Document. The 

information in this preamble is 

organized as follows: 

I. General Information 

A. What is the statutory authority for this 

action? 

B. Does this action apply to me? 

C. Where can I get a copy of this document 

and other related information? 

D. What should I consider as I prepare my 

comments for the EPA? 

II. Background 

A. What is this source category and how 

did the MACT standard regulate its HAP 

emissions? 

B. What data collection activities were 

conducted to support this action? 

III. Analyses Performed 

A. How did we address unregulated 

emission sources? 

B. How did we estimate risks posed by the 

source category? 

C. How did we consider the risk results in 

making decisions for this proposal? 

D. How did we perform the technology 

review? 

E. What other issues are we addressing in 

this proposal? 

IV. Analytical Results and Proposed 

Decisions 

A. What are the results of our analyses and 

proposed decisions regarding 

unregulated emissions sources? 

B. What are the results of the risk 

assessments? 

C. What are our proposed decisions 

regarding risk acceptability and ample 

margin of safety? 

D. What are the results and proposed 

decisions based on our technology 

review? 

E. What other actions are we proposing? 

F. Compliance dates 

V. Summary of Cost, Environmental, and 

Economic Impacts 

A. What are the affected sources? 

B. What are the air quality impacts? 

C. What are the cost impacts? 

D. What are the economic impacts? 

E. What are the benefits? 

VI. Request for Comments 


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1 ‘‘Adverse environmental effect’’ is defined in 

CAA section 112(a)(7) 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. 

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. What is the statutory authority for 

this action? 

Section 112 of the CAA establishes a 

two-stage regulatory process to address 

emissions of hazardous air pollutants 

(HAP) from stationary sources. In the 

first stage, after the EPA has identified 

categories of sources emitting one or 

more of the HAP listed in section 112(b) 

of the CAA, section 112(d) of the CAA 

calls for us to promulgate national 

emission standards for hazardous air 

pollutants (NESHAP) for those sources. 

‘‘Major sources’’ are those that emit or 

have the potential to emit (PTE) 10 tons 

per year (tpy) or more of a single HAP 

or 25 tpy or more of any combination of 

HAP. For major sources, these 

technology-based standards must reflect 

the maximum degree of emission 

reductions of HAP achievable (after 

considering cost, energy requirements 

and nonair quality health and 

environmental impacts) and are 

commonly referred to as maximum 

achievable control technology (MACT) 

standards. 

MACT standards are to reflect 

application of measures, processes, 

methods, systems or techniques 

including, but not limited to, measures 

which (1) reduce the volume of or 

eliminate emissions of 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)–(E). The MACT 

standard may take the form of a design, 

equipment, work practice or operational 

standard where the EPA first determines 

that either (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 sections 112(h)(1)–(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 emission control that is 

achieved in practice by the bestcontrolled similar source. The MACT 

floors for existing sources can be less 

stringent than floors for new sources, 

but they cannot be less stringent than 

the average emission limitation 

achieved by the best-performing 

12 percent of existing sources in the 

category or subcategory (or the bestperforming five sources for categories or 

subcategories with fewer than 30 

sources). In developing MACT 

standards, we must also consider 

control options that are more stringent 

than the floor. We may establish 

standards more stringent than the floor 

(‘‘beyond the floor’’ standards) based on 

the consideration of the cost of 

achieving the emissions reductions and 

any nonair quality health and 

environmental impacts and energy 

requirements. No beyond the floor 

standards are proposed in this 

rulemaking action. 

The EPA is then required to review 

these technology-based standards and to 

revise them ‘‘as necessary (taking into 

account developments in practices, 

processes, and control technologies)’’ no 

less frequently than every 8 years, under 

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

this review, the EPA is not obliged to 

completely recalculate the prior MACT 

determination. NRDC v. EPA, 529 F.3d 

1077, 1084 (D.C. Cir. 2008). 

The second stage in standard-setting 

focuses on reducing any remaining 

‘‘residual’’ risk according to CAA 

section 112(f). This provision requires, 

first, that the EPA prepare a Report to 

Congress discussing (among other 

things) methods of calculating risk 

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 this report 

(Residual Risk Report to Congress, EPA– 

453/R–99–001) in March 1999. Congress 

did not act in response to the report, 

thereby triggering the EPA’s obligation 

under CAA section 112(f)(2) to analyze 

and address residual risk. 

CAA section 112(f)(2) requires us to 

determine, for source categories subject 

to MACT standards, whether the 

emissions standards provide an ample 

margin of safety to protect public health. 

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 1-in-1 

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 

are sufficiently protective. NRDC v. 

EPA, 529 F.3d 1077, 1083 (D.C. Cir. 

2008). (‘‘If EPA determines that the 

existing technology-based standards 

provide an ‘‘ample margin of safety,’’ 

then the agency is free to readopt those 

standards during the residual risk 

rulemaking.’’) The EPA must also adopt 

more stringent standards, if necessary, 

to prevent an adverse environmental 

effect 1 but must consider cost, energy, 

safety and other relevant factors in 

doing so. 

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

preserves our use of a two-step process 

for developing standards to address any 

residual risk and our interpretation of 

‘‘ample margin of safety’’ developed in 

the National Emission 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 

first step in this process is the 

determination of acceptable risk. The 

second step provides for an ample 

margin of safety to protect public health, 

which is the level at which the 

standards are set (unless a more 


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2Although 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. 

stringent standard is required to 

prevent, taking into consideration costs, 

energy, safety, and other relevant 

factors, an adverse environmental 

effect). 

The terms ‘‘individual most exposed,’’ 

‘‘acceptable level,’’ and ‘‘ample margin 

of safety’’ are not specifically defined in 

the CAA. However, CAA section 

112(f)(2)(B) preserves the interpretation 

set out in the Benzene NESHAP, and the 

United States Court of Appeals for the 

District of Columbia Circuit in NRDC v. 

EPA, 529 F.3d 1077, concluded that the 

EPA’s interpretation of subsection 

112(f)(2) is a reasonable one. See NRDC 

v. EPA, 529 F.3d at 1083 (‘‘[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’’). (D.C. Cir. 2008). See also, A 

Legislative History of the Clean Air Act 

Amendments of 1990, volume 1, p. 877 

(Senate debate on Conference Report). 

We notified Congress in the Residual 

Risk Report to Congress that we 

intended to use the Benzene NESHAP 

approach in making CAA section 112(f) 

residual risk determinations (EPA–453/ 

R–99–001, p. ES–11). 

In the Benzene NESHAP, we stated as an 

overall objective: 

* * * in protecting public health with an 

ample margin of safety, we strive 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-in1 million] the estimated risk that a person 

living near a facility would have if he or she 

were exposed to the maximum pollutant 

concentrations for 70 years. 

The agency also stated that, ‘‘The 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 risk 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.’’ The agency 

went on to conclude that ‘‘estimated 

incidence would be weighed along with 

other health risk information in judging 

acceptability.’’ As explained more fully 

in our Residual Risk Report to Congress, 

the EPA does not define ‘‘rigid line[s] of 

acceptability,’’ but considers rather 

broad objectives to be weighed with a 

series of other health measures and 

factors (EPA–453/R–99–001, p. ES–11). 

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’’ 

(Residual Risk Report to Congress, p. 

178, quoting the Vinyl Chloride 

decision at 824 F.2d 1165) recognizing 

that our world is not risk-free. 

In the Benzene NESHAP, we stated 

that ‘‘EPA will generally presume that if 

the risk to [the maximum exposed] 

individual is no higher than 

approximately 1-in-10 thousand, that 

risk level is considered acceptable.’’ 

54 FR 38045. We discussed the 

maximum individual lifetime cancer 

risk (or maximum individual risk (MIR)) 

as being ‘‘the estimated risk that a 

person living near a plant would have 

if he or she were exposed to the 

maximum pollutant concentrations for 

70 years.’’ Id. We explained that this 

measure of risk ‘‘is an estimate of the 

upper bound of risk based on 

conservative assumptions, such as 

continuous exposure for 24 hours per 

day for 70 years.’’ Id. We acknowledge 

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 

maximum individual lifetime cancer 

risk as a metric for determining 

acceptability, we acknowledged in the 

1989 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. 

The agency also explained in the 1989 

Benzene NESHAP the following: ‘‘In 

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-kilometer (km) 

exposure radius around facilities, the 

science policy assumptions and 

estimation uncertainties associated with 

the risk measures, weight of the 

scientific evidence for human health 

effects, other quantified or unquantified 

health effects, effects due to co-location 

of facilities and co-emission of 

pollutants.’’ Id. 

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 explained in the Benzene 

NESHAP, ‘‘[e]ven though the risks 

judged ‘acceptable’ by the EPA in the 

first step of the Vinyl Chloride inquiry 

are already low, 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.’’ 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. 

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 CAA section 112(f). 54 FR 

38046. 

As discussed in the previous section 

of this preamble, we apply a two-step 

process for developing standards 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) 2 of approximately 1-in-10 

thousand [i.e., 100-in-1 million].’’ 54 FR 

38045. In the second step of the process, 

the EPA sets the standard at a level that 

provides 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. 

In past residual risk determinations, 

the EPA presented a number of human 

health risk metrics associated with 

emissions from the category under 

review, including: The MIR; the 

numbers of persons in various risk 

ranges; cancer incidence; the maximum 

noncancer hazard index (HI); and the 

maximum acute noncancer hazard. In 

estimating risks, the EPA considered 


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source categories under review that are 

located near each other and that affect 

the same population. The EPA provided 

estimates of the expected difference in 

actual emissions from the source 

category under review and emissions 

allowed pursuant to the source category 

MACT standard. The EPA also 

discussed and considered risk 

estimation uncertainties. The EPA is 

providing this same type of information 

in support of these actions. 

The agency acknowledges that the 

Benzene NESHAP provides flexibility 

regarding what factors the EPA might 

consider in making our determinations 

and how they might be weighed for each 

source category. In responding to 

comment on our policy under the 

Benzene NESHAP, the EPA explained 

that: ‘‘The policy chosen by the 

Administrator permits consideration of 

multiple measures of health risk. Not 

only can the MIR figure be considered, 

but also incidence, the presence of 

noncancer 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.’ ’’ 

For example, the level of the MIR is 

only one factor to be weighed in 

determining acceptability of risks. The 

Benzene NESHAP explains ‘‘an MIR of 

approximately 1-in-10 thousand should 

ordinarily be the upper end of the range 

of acceptability. As risks increase above 

this benchmark, they become 

presumptively less acceptable under 

CAA section 112, and would be 

weighed with the other health risk 

measures and information in making an 

overall judgment on acceptability. Or, 

the agency may find, in a particular 

case, that a risk that includes MIR less 

than the presumptively acceptable level 

is unacceptable in the light of other 

health risk factors.’’ Similarly, with 

regard to the ample margin of safety 

analysis, the Benzene NESHAP states 

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.’’ 

B. Does this action apply to me? 

The regulated industrial source 

category that is the subject of this 

proposal is listed in Table 2 of this 

preamble. Table 2 of this preamble is 

not intended to be exhaustive, but rather 

provides a guide for readers regarding 

the entities likely to be affected by this 

proposed action. These standards, once 

finalized, will be directly applicable to 

affected sources. Federal, State, local, 

and Tribal government entities are not 

affected by this proposed action. As 

defined in the source category listing 

report published by the EPA in 1992, 

the Primary Aluminum Reduction Plant 

source category is defined as any facility 

which produced primary aluminum by 

the electrolytic reduction process. 

TABLE 2—NESHAP AND INDUSTRIAL SOURCE CATEGORIES AFFECTED BY THIS PROPOSED ACTION

Source category NESHAP NAICS code 1 MACT code 2

Primary Aluminum Reduction Plants ........................ Primary Aluminum Reduction Plants ........................ 331312 0023 

1 North American Industry Classification System. 

2 Maximum Achievable Control Technology. 

C. 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 

proposal will also be available on the 

World Wide Web (WWW) through the 

EPA’s Technology Transfer Network 

(TTN). Following signature by the EPA 

Administrator, a copy of this proposed 

action will be posted on the TTN’s 

policy and guidance page for newly 

proposed or promulgated rules at the 

following address: http://www.epa.gov/

ttn/atw/rrisk/rtrpg.html. The TTN 

provides information and technology 

exchange in various areas of air 

pollution control. 

Additional information is available on 

the residual risk and technology review 

(RTR) Web page at: http://www.epa.gov/ 

ttn/atw/rrisk/rtrpg.html. This 

information includes source category 

descriptions and detailed emissions 

estimates and other data that were used 

as inputs to the risk assessments. 

D. What should I consider as I prepare 

my comments for the EPA? 

Submitting CBI. Do not submit 

information containing CBI to the EPA 

through http://www.regulations.gov or 

email. Clearly mark the part or all of the 

information that you claim to be CBI. 

For CBI information on a disk or CD 

ROM that you mail to the EPA, mark the 

outside of the disk or CD ROM as CBI 

and then identify electronically within 

the disk or CD ROM the specific 

information that is claimed as CBI. In 

addition to one complete version of the 

comment that includes information 

claimed as CBI, a copy of the comment 

that does not contain the information 

claimed as CBI must be submitted for 

inclusion in the public docket. If you 

submit a CD ROM or disk that does not 

contain CBI, mark the outside of the 

disk or CD ROM clearly that it does not 

contain CBI. Information not marked as 

CBI will be included in the public 

docket and the EPA’s electronic public 

docket without prior notice. Information 

marked as CBI will not be disclosed 

except in accordance with procedures 

set forth in 40 CFR part 2. Send or 

deliver information identified as CBI 

only to the following address: Roberto 

Morales, OAQPS Document Control 

Officer (C404–02), Office of Air Quality 

Planning and Standards, U.S. 

Environmental Protection Agency, 

Research Triangle Park, North Carolina 

27711, Attention Docket ID Number 

EPA–HQ–OAR–2011–0797. 

II. Background 

A. What is this source category and how 

did the MACT standard regulate its HAP 

emissions? 

The NESHAP (or MACT rule) for the 

Primary Aluminum Reduction Plants 

was promulgated on October 7, 1997 (62 

FR 52407) and amended on November 

2, 2005 (70 FR 66285). The rule is 

applicable to facilities with affected 

sources associated with the production 

of aluminum by electrolytic reduction. 

Aluminum is produced from refined 


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bauxite ore (also known as alumina), 

using an electrolytic reduction process 

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

The raw materials include alumina, 

coke, pitch and fluoride salts. According 

to information available on the Web site 

of The Aluminum Association, Inc. 

(http://www.aluminum.org) 

approximately 50 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 15 

facilities located in the United States 

that are subject to the requirements of 

this NESHAP: 14 primary aluminum 

production plants and one carbon-only 

prebake anode production facility. 

These 14 primary aluminum production 

plants have approximately 53 potlines 

that produce aluminum. Each plant has 

a paste production operation, and 12 of 

the 14 plants have anode bake furnaces. 

Twelve of the 14 facilities utilize 

prebake potlines; the other 2 utilize 

Soderberg potlines. According to The 

Aluminum Association, Inc., due to a 

decrease in demand for aluminum, four 

of the 14 facilities are currently idle 

including 1 Soderberg facility. The 

major HAPs emitted by these facilities 

are carbonyl sulfide (COS), hydrogen 

fluoride (HF), 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 reduction. 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 the installation of a dry alumina 

scrubber (with a baghouse to collect the 

alumina and other particulate matter). 

The MACT control technology typically 

used for anode bake furnaces is a dry 

alumina scrubber, and a capture system 

vented to a dry coke scrubber is used for 

control of paste production plants. See 

Table 3 for the emission limits. 

TABLE 3—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 .................

POM .............

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

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

1 CWPB1 = 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 primary aluminum plant operated by NSA in Hawesville, Kentucky. 

HSS = Horizontal stud Soderberg potline. 

SWPB = Side-worked prebake potline. 

VSS1 = Vertical stud Soderberg potline at Northwest Aluminum in The Dalles, Oregon, or at Columbia Aluminum in Goldendale, Washington. 

VSS2 = Vertical stud Soderberg potlines at Columbia Falls Aluminum in Columbia Falls, Montana. 

TABLE 4—SUMMARY OF CURRENT MACT EMISSION LIMITS FOR NEW SOURCES UNDER THE 1997 NESHAP AND 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 .................

POM .............

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

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

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

emissions by 95 percent or greater. 


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The 1997 NESHAP for primary 

aluminum reduction plants incorporates 

new source performance standards for 

potroom groups; these emission limits 

are listed in Table 4. 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. 

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 parameter monitoring for 

each emission control device, a 

monitoring device to track daily weight 

of aluminum produced, daily inspection 

for visible emissions, and daily 

inspection of wet roof scrubbers. 

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 particulate matter or 

gaseous form. 

B. What data collection activities were 

conducted to support this action? 

For the Primary Aluminum Reduction 

Plant source category, we compiled a 

preliminary dataset using available 

information, reviewed the data, and 

made changes where necessary. The 

preliminary dataset was based on data 

in the 2002 National Emissions 

Inventory (NEI) Final Inventory, Version 

1 (made publicly available on February 

26, 2006), and the 2005 National 

Emissions Inventory (NEI), version 2.0 

(made publicly available in October 

2008). The NEI is a database that 

contains information about sources that 

emit criteria air pollutants, their 

precursors, and HAP. The NEI database 

includes estimates of annual air 

pollutant emissions from point and 

volume sources, emission release 

characteristic data such as height, 

velocity, temperature and location 

latitude/longitude coordinates. 

We reviewed the NEI datasets, 

corrected geographic coordinates and 

stack parameters in consultation with 

the facilities, and made changes based 

on available information. We also 

reviewed the emissions and other data 

to identify data anomalies that could 

affect risk estimates. The 2005 NEI was 

then updated to develop the 2005 

National Air Toxics Assessment (NATA) 

Inventory. Subsequently, in April 2011, 

we received test data and other 

information through an Information 

Collection Request (ICR) from 11 of the 

15 facilities in the source category. 

These ICR data were then used along 

with the 2005 NATA inventory data to 

develop the emissions dataset for this 

source category, which includes our 

best estimates of actual emissions of 

HAP for the facilities. This dataset was 

then used in the risk modeling analyses 

to estimate the risks due to actual 

emissions for the source category. 

POM emissions were allocated to 

specific POM compounds on the basis 

of the fractional contributions of these 

compounds to the actual POM 

emissions, as determined (as 

appropriate) from an average of test data 

for two prebake potlines and an average 

of data from two Soderberg facilities. 

Based on knowledge of the industry and 

previous testing, we could reasonably 

expect emissions of approximately 23 

POM specific POM compounds from 

primary aluminum production facilities. 

The allocation incorporated POM 

emissions at 50 percent of the detection 

limit for those compounds ‘‘reported as 

below detection limit.’’ The use of 50 

percent of the detection limit is more 

conservative than assuming that these 

compounds were not present; an 

assumption that the compounds were 

present at the detection limit would be 

an overestimation. The assumption that 

these compounds were present at 50 

percent of the detection limit 

represented the midpoint of two 

extreme options. For Soderberg potline 

stacks, six out of 38 measurements were 

below the detection limit. For Soderberg 

potroom roof vents, 10 out of 38 

measurements were below the detection 

limit. For prebake potline stacks, 21 out 

of 38 measurements were below the 

detection limit. For prebake potroom 

roof vents, 25 out of 38 measurements 

were below the detection limit. 

To estimate allowable emissions, we 

analyzed the emissions data gathered 

from the 2002 NEI, the 2005 NEI and 

responses to the ICR described above. 

Based on that analysis, we estimated 

that allowable emissions were generally 

about 1.5 times higher than actual 

emissions. Therefore, to calculate 

allowable emissions we assumed that 

allowable emissions were 1.5 times 

greater than 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 were 

about 1.9 times higher than actual 

emissions. 

Actual emissions of COS for the 

industry are estimated to be about 4,400 

tons per year (tpy), with an average of 

about 330 tons per facility. Actual 

emissions of HF are estimated to be 

about 1,900 tpy with an average of about 

160 tpy per facility. Estimated emissions 

of speciated compounds of POM were 

much lower. Estimated actual emissions 

of identified POM species totaled 

approximately 180 tpy for the industry. 

Moreover, POM emissions are much 

higher from Soderberg facilities 

compared to prebake facilities. The 

average POM emissions from prebake 

facilities are about 4.5 tpy per facility, 

and the average POM emissions for 

Soderberg facilities are about 60 tpy per 

facility. We estimate that approximately 

one-third of the emissions of POM for 

both types of potrooms come from the 

control device stack, and the remainder 

are secondary emissions emitted from 

potroom vents. This estimate is based 

on a summary of emissions derived 

from reports of emission testing 

conducted at two prebake facilities and 

two Soderberg facilities (‘‘Industry 

Review of Draft POM Speciation and 

Emissions Data,’’ December 19, 2007). 

The emissions data, calculations and 

risk assessment inputs for the Primary 

Aluminum Reduction Plant source 

category are described further in Draft 

Development of the RTR Emissions 

Dataset for the Primary Aluminum 

Production Source Category which is 

available in the docket for this proposed 

rulemaking. 

III. Analyses Performed 

In this section we describe the 

analyses performed to support the 

proposed decisions for the RTR for this 

source category. 

A. How did we address unregulated 

emissions sources? 

In the course of evaluating the 

Primary Aluminum Reduction Plant 

source category, we identified certain 

HAP for which we failed to establish 

emission standards in the original 

MACT. See National Lime v. EPA, 233 

F. 3d 625, 634 (DC Cir. 2000) (the EPA 

has ‘‘clear statutory obligation to set 

emissions standards for each listed 

HAP’’). 

We evaluated establishing emissions 

limits for COS for the source category 

and for POM for various emissions 

points that had not been regulated in the 

1997 MACT rule or in the 2005 


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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. 

amendments. Section 112(d)(3)(B) of the 

CAA requires that the MACT standards 

for existing sources be at least as 

stringent as the average emissions 

limitation achieved by the best 

performing five sources (for which the 

Administrator has or could reasonably 

obtain emissions information) in a 

category with fewer than 30 sources. 

The Primary Aluminum source category 

consists of fewer than 30 sources. 

The EPA must exercise its judgment, 

based on an evaluation of the relevant 

factors and available data, to determine 

the level of emissions control that has 

been achieved by the best performing 

sources under variable conditions. It is 

recognized in the case law that the EPA 

may consider variability in estimating 

the degree of emissions reduction 

achieved by best-performing sources 

and in setting MACT floors. See 

Mossville Envt’l Action Now v. EPA, 370 

F.3d 1232, 1241–42 (DC Cir 2004) 

(holding that the EPA may consider 

emissions variability in estimating 

performance achieved by bestperforming sources and may set the 

floor at a level that a best-performing 

source can expect to meet ‘‘every day 

and under all operating conditions’’). 

More details on how we calculate 

MACT floors and how we account for 

variability are described in the Draft 

MACT Floor Analysis for the Primary 

Aluminum Source Category which is 

available in the docket for this proposed 

action. 

Carbonyl sulfide (COS) was not 

regulated in the 1997 NESHAP or in the 

2005 amendments for Primary 

Aluminum Reduction Plants. In this 

action we analyzed the available data 

and evaluated options for developing 

MACT standards for this HAP. Based on 

all our analyses, which are described in 

section IV.A of this preamble, we 

concluded that establishing a standard 

based on a mass balance equation would 

be the most appropriate approach. 

Therefore, we are proposing MACT 

standards for COS in today’s action 

based on use of a mass balance equation 

to derive COS emissions based on data 

on anode coke sulfur content, anode 

consumption and aluminum 

production. 

Polycyclic organic matter (POM) 

emissions from prebake potlines were 

also not regulated in the 1997 NESHAP 

or in the 2005 amendments. We are 

proposing MACT limits for new and 

existing prebake potlines in today’s 

action based on available data. Finally, 

the 1997 NESHAP included MACT 

standards for new pitch storage tanks, 

which required a 95 percent reduction 

in emissions. However, the rule had no 

limits for existing storage tanks. We are 

proposing that existing tanks will be 

subject to the same standard (i.e., 

minimum of 95 percent reduction of 

POM emissions). At least three facilities 

are currently achieving this level of 

control on existing tanks. 

Further details about the analyses, the 

results and proposed decisions 

regarding the proposed MACT limits 

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

112(d)(3) are presented in section IV.A 

of this preamble. 

B. How did we estimate risks posed by 

the source category? 

The EPA conducted risk assessments 

that provided estimates of the MIR 

posed by the HAP emissions for each 

source in the category, the 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 assessments also provided 

estimates of the distribution of cancer 

risks within the exposed populations, 

cancer incidence and an evaluation of 

the potential for adverse environmental 

effects for each source category. The risk 

assessments consisted of seven primary 

steps, as discussed below. The docket 

for this rulemaking contains the 

following document which provides 

more information on the risk assessment 

inputs and models: Draft Residual Risk 

Assessment for the Primary Aluminum 

Reduction Plant Source Category. The 

methods used to assess risks (as 

described in the seven primary steps 

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

Science Advisory Board (SAB) in 2009 

and described in their peer review 

report issued in 2010 3; they are also 

consistent with the key 

recommendations contained in that 

report. 

1. Establishing the Nature and 

Magnitude of Actual Emissions and 

Identifying the Emissions Release 

Characteristics 

As discussed in section II.B of this 

preamble, we used a dataset consisting 

of the estimated actual and allowable 

emissions as the basis for the risk 

assessment. In addition to the quality 

assurance (QA) of the emissions and 

associated parameters contained in the 

dataset, we also checked the coordinates 

of every facility in the dataset through 

visual observations using tools such as 

Google Earth and ArcView. Where 

coordinates were found to be incorrect, 

we identified and corrected them to the 

extent possible. We also performed QA 

of the emissions data and release 

characteristics to ensure there were no 

outliers. 

2. Establishing the Relationship 

Between Actual Emissions and MACTAllowable Emissions Levels 

The available emissions data in the 

MACT dataset include estimates of the 

mass of HAP actually emitted during the 

specified annual time period. These 

‘‘actual’’ emission levels are often lower 

than the emission levels that a facility 

might be allowed to emit and still 

comply with the MACT standards. The 

emissions level allowed to be emitted by 

the MACT standards is referred to as the 

‘‘MACT-allowable’’ emissions level. 

This represents the highest emissions 

level that could be emitted by the 

facility without violating the MACT 

standards. 

We discussed the use of both MACTallowable and actual emissions in the 

final Coke Oven Batteries residual risk 

rule (70 FR 19998–19999, April 15, 

2005) and in the proposed and final 

Hazardous Organic NESHAP residual 

risk rules (71 FR 34428, June 14, 2006, 

and 71 FR 76609, December 21, 2006, 

respectively). In those previous actions, 

we noted that assessing the risks at the 

MACT-allowable level is inherently 

reasonable since these risks reflect the 

maximum level sources could emit and 

still comply with national emission 

standards. But 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. (54 FR 38044, 

September 14, 1989.) 

Further explanation is provided in the 

document Draft Development of the 

RTR Emissions Dataset for the Primary 

Aluminum Production Source Category 

which is available in the docket for this 

proposed rulemaking. 

3. Conducting Dispersion Modeling, 

Determining Inhalation Exposures and 

Estimating Individual and Population 

Inhalation Risks 

Both long-term and short-term 

inhalation exposure concentrations and 

health risks from each facility in the 

source category addressed in this 

proposal were estimated using the 

Human Exposure Model (HEM) 

(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 


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76268 Federal Register / Vol. 76, No. 234 / Tuesday, December 6, 2011 / Proposed Rules 

4U.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). 

5A census block is generally the smallest 

geographic area for which census statistics are 

tabulated. 

6U.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. 

7See the Risk Assessment for Source Categories 

document available in the docket for a list of HAP 

with a mutagenic mode of action. 8U.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. 

9U.S. EPA. Science Policy Council Cancer 

Guidelines Implementation Workgroup 

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

June 14, 2006. 

10These classifications also coincide with the 

terms ‘‘known carcinogen, probable carcinogen and 

possible carcinogen,’’ respectively, which are the 

terms advocated in the EPA’s previous Guidelines 

for Carcinogen Risk Assessment, published in 1986 

(51 FR 33992, September 24, 1986). Summing the 

risks of these individual compounds to obtain the 

cumulative cancer risks is an approach that was 

recommended by the EPA’s SAB in their 2002 peer 

review of EPA’s NATA entitled, NATA—Evaluating 

the National-scale Air Toxics Assessment 1996 

Data—an SAB Advisory, available at: http:// 

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

214C6E915BB04E14852570CA007A682C/$File/ 

ecadv02001.pdf. 

and short-term inhalation exposures to 

individuals residing within 50 km of the 

modeled sources and (3) estimating 

individual and population-level 

inhalation risks using the exposure 

estimates and quantitative doseresponse information. 

The dispersion model used by HEM– 

3 is AERMOD, which is one of the 

EPA’s preferred models for assessing 

pollutant concentrations from industrial 

facilities.4 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 (1991) of hourly surface and upper 

air observations for more than 158 

meteorological stations, selected to 

provide coverage of the United States 

and Puerto Rico. A second library of 

United States Census Bureau census 

block 5 internal point locations and 

populations provides the basis of 

human exposure calculations (Census, 

2000). In addition, for each census 

block, the census library includes the 

elevation and controlling hill height, 

which are also used in dispersion 

calculations. A third library of pollutant 

unit risk factors and other health 

benchmarks is used to estimate health 

risks. These risk factors and health 

benchmarks are the latest values 

recommended by the EPA for HAP and 

other toxic air pollutants. These values 

are available at http://www.epa.gov/ttn/ 

atw/toxsource/summary.html and are 

discussed in more detail later in this 

section. 

In developing the risk assessment for 

chronic exposures, we used the 

estimated annual average ambient air 

concentration of each of the 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 an inhabited census block. 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) by its unit risk estimate 

(URE), which 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 the 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. 

Polycyclic organic matter (POM), a 

carcinogenic HAP with a mutagenic 

mode of action, is emitted by the 

facilities in this source category.6 For 

this compound group,7 the agedependent adjustment factors (ADAF) 

described in the EPA’s Supplemental 

Guidance for Assessing Susceptibility 

from Early-Life Exposure to 

Carcinogens 8 were applied. This 

adjustment has the effect of increasing 

the estimated lifetime risks for POM by 

a factor of 1.6. In addition, although 

only a small fraction of the total POM 

emissions were not reported 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 9

recommends applying the Supplemental 

Guidance to all carcinogenic polycyclic 

aromatic hydrocarbons 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. 

Incremental individual lifetime 

cancer risks associated with emissions 

from the source category were estimated 

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 10) emitted by the modeled 

source. Cancer incidence and the 

distribution of individual cancer risks 

for the population within 50 km of any 

source were also estimated for the 

source category as part of these 

assessments by summing individual 

risks. A distance of 50 km is consistent 

with both the analysis supporting the 

1989 Benzene NESHAP (54 FR 38044) 

and the limitations of Gaussian 

dispersion models, including AERMOD. 

To assess risk of noncancer 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 for chronic 

exposures is the estimated chronic 

exposure divided by the chronic 

reference level, which is either the EPA 

reference concentration (RfC), 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,’’ 

or, in cases where an RfC from the 

EPA’s IRIS database is not available, a 

value from the following prioritized 

sources: (1) The agency for Toxic 

Substances and Disease Registry 

Minimum Risk Level, which is defined 

as ‘‘an estimate of daily human 

exposure to a substance that is likely to 

be without an appreciable risk of 

adverse effects (other than cancer) over 

a specified duration of exposure’’; (2) 

the CalEPA Chronic Reference Exposure 

Level (REL), which is defined as ‘‘the 

concentration level at or below which 

no adverse health effects are anticipated 

for a specified exposure duration;’’ or 


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11NAS, 2001. Standing Operating Procedures for 

Developing Acute Exposure Levels for Hazardous 

Chemicals, page 2. 

12ERP Committee Procedures and 

Responsibilities. November 1, 2006. American 

Industrial Hygiene Association. 

(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. 

Screening estimates of acute 

exposures and risks were also evaluated 

for each of the HAP at the point of 

highest off-site exposure for each facility 

(i.e., not just the census block 

centroids), assuming that a person is 

located at this spot at a time when both 

the peak (hourly) emission rates from 

each emission point at the facility and 

worst-case dispersion conditions occur. 

The acute HQ is the estimated acute 

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

values were calculated 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 emission rates, 

meteorology and exposure location for 

our acute analysis. 

As described in the CalEPA’s Air 

Toxics Hot Spots Program Risk 

Assessment Guidelines, Part I, The 

Determination of Acute Reference 

Exposure Levels for Airborne Toxicants, 

an acute REL value (http:// 

www.oehha.ca.gov/air/pdf/acuterel.pdf) 

is defined as ‘‘the concentration level at 

or below which no adverse health 

effects are anticipated for a specified 

exposure duration.’’ Acute REL values 

are based on the most sensitive, 

relevant, adverse health effect reported 

in the medical and toxicological 

literature. Acute REL values are 

designed to protect the most sensitive 

sub-populations (e.g., asthmatics) by the 

inclusion of margins of safety. Since 

margins of safety are incorporated to 

address data gaps and uncertainties, 

exceeding the acute 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/ 

opptintr/aegl/pubs/sop.pdf),11 ‘‘the 

NRC’s previous name for acute exposure 

levels—community emergency exposure 

levels—was replaced by the term AEGL 

to reflect the broad application of these 

values to planning, response, and 

prevention in the community, the 

workplace, transportation, the military, 

and the remediation of Superfund 

sites.’’ 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.’’ The document lays out the 

purpose and objectives of AEGL by 

stating (page 21) 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, highpriority chemicals.’’ In detailing the 

intended application of AEGL values, 

the document states (page 31) 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.’’ 

The AEGL–1 value is then specifically 

defined as ‘‘the airborne concentration 

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.’’ 

The document also notes (page 3) 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.’’ Similarly, the 

document defines AEGL–2 values as 

‘‘the airborne concentration (expressed 

as ppm or mg/m3) 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.’’ 

ERPG values are derived for use in 

emergency response, as described in the 

American Industrial Hygiene 

Association’s document entitled, 

Emergency Response Planning 

Guidelines (ERPG) Procedures and 

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

1documents/committees/ 

ERPSOPs2006.pdf) which states that, 

‘‘Emergency Response Planning 

Guidelines were developed for 

emergency planning and are intended as 

health based guideline concentrations 

for single exposures to chemicals.’’ 12

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.’’ 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 

1 hour without experiencing or 

developing irreversible or other serious 

health effects or symptoms which could 

impair an individual’s ability to take 

protective action.’’ 

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; in these instances, 

higher severity level AEGL–2 or ERPG– 

2 values are compared to our modeled 

exposure levels to assess potential for 

acute concerns. 

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 similar to the corresponding 

ERPG–1 values, and AEGL–2 values are 

often similar 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, we developed 

estimates of maximum hourly emission 

rates by multiplying the average actual 

annual hourly emission rates by a factor 

to cover routinely variable emissions. 

Acute risk modeling is conducted under 

the assumption that peak emissions are 

ten times greater than long term average 


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13The 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. 

emissions, in the absence of information 

regarding the variability of the 

emissions. 

With respect to routine variable 

emissions, primary aluminum potlines 

have a more consistent emissions profile 

than many other sources because these 

emissions actually reflect the average of 

the emissions from approximately 100 

individual pots which operate in cycles 

that are not in phase with each other. 

Thus any variability associated with 

aluminum levels or electrode 

replacement for a particular pot may be 

damped out by the other pots at 

different stages. Alcoa provided to EPA 

a series of hourly hydrogen fluoride 

concentration data for two potlines at 

their Wenatchee facility. Approximately 

2,075 consecutive hourly readings were 

provided based on Fourier Transform 

Infrared measurements at the roof vents. 

Alcoa found that the ratio of the 

maximum HAP emission rate to the 

average HAP emission rate for these two 

potlines were 2.7 and 5.6. Only one 

value out 2,075 consecutive hour 

samples (0.05 percent) was more than 5 

times the average (i.e., 99.95 percent of 

values were less than 5 times the 

average). 

This dataset was then combined and 

subjected to two statistical analysis 

techniques: The upper prediction limit 

(UPL) calculated assuming a log-normal 

distribution after adjusting for temporal 

correction and extreme value theory. 

The average of the concentration values 

is 514 mg/m3. The 99 percent UPL was 

calculated at 2,215 mg/m, which 

corresponds to 4.3 times the mean. 

Using the extreme value theory, the 

99.9 percentile estimate of the 

generalized extreme value distribution 

(corresponding to 1 observation in 1000) 

was 2,306 mg/m3, which corresponds to 

4.5 times the mean. Based on these data, 

a source category factor of 5 times the 

average hourly emissions rate, rather 

than the default factor of 10, was used 

in the acute screening assessment. 

When worst-case HQ values from the 

initial acute screen step were less than 

1, acute impacts were deemed negligible 

and no further analysis was performed. 

In cases where an acute HQ value from 

the screening step indicated the 

potential for acute risk, we further 

analyzed these values by considering 

additional site-specific data to develop 

a relatively more refined estimate of the 

potential for acute impacts of concern. 

This site-specific data includes the 

facility layout that was used to 

distinguish facility property from an 

area where the public could be exposed. 

These refinements are discussed in the 

Draft Residual Risk Assessment for the 

Primary Aluminum Production Source 

Category document, which is available 

in the docket for this proposed 

rulemaking. 

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 

emission 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. However, we recognize that 

having this level of data is rare, hence 

our use of the multiplier approach. 

To better characterize the potential 

health risks associated with estimated 

acute exposures to HAP, and in 

response to a key recommendation from 

the SAB’s peer review of the EPA’s RTR 

risk assessment methodologies,13 we 

generally examine a wider range of 

available acute health metrics 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. Comparisons of the 

estimated maximum off-site 1-hour 

exposure levels are not typically made 

to occupational levels for the purpose of 

characterizing public health risks in 

RTR assessments. This is because they 

are developed for working-age adults 

and are not generally considered 

protective for the general public. We 

note that occupational ceiling values 

are, for most chemicals, set at levels 

higher than a 1-hour AEGL–1. 

4. Conducting Multi-Pathway Exposure 

and Risk Screening 

The potential for significant human 

health risks due to exposures via routes 

other than inhalation (i.e., multipathway exposures) and the potential 

for adverse environmental impacts were 

evaluated in a three-step process. In the 

first step, we determined whether any 

facilities emitted any PB–HAP (HAP 

known to be persistent and bioaccumulative in the environment). 

There are 14 PB–HAP compounds or 

compound classes identified for this 

screening in the EPA’s Air Toxics Risk 

Assessment Library (available at http:// 

www.epa.gov/ttn/fera/ 

risk_atra_vol1.html). They are cadmium 

compounds, chlordane, chlorinated 

dibenzodioxins and furans, 

dichlorodiphenyldichloroethylene, 

heptachlor, hexachlorobenzene, 

hexachlorocyclohexane, lead 

compounds, mercury compounds, 

methoxychlor, polychlorinated 

biphenyls, POM, toxaphene and 

trifluralin. 

Since POM is a PB–HAP and is 

emitted by all facilities in this source 

category, we proceeded to the second 

step of the evaluation to screen for 

potentially significant multi-pathway 

risks due to POM emissions. In this 

step, we determined whether the 

facility-specific emission rates of POM 

were large enough to create the potential 

for significant non-inhalation human or 

environmental risks under reasonable 

worst-case conditions. To facilitate this 

step, we have developed emission rate 

thresholds for each PB–HAP using a 

hypothetical worst-case screening 

exposure scenario developed for use in 

conjunction with the EPA’s TRIM.FaTE 

model. The hypothetical screening 

scenario was subjected to a sensitivity 

analysis to ensure that its key design 

parameters were established such that 

environmental media concentrations 

were not underestimated (i.e., to 

minimize the occurrence of false 

negatives or results that suggest that 

risks might be acceptable when, in fact, 

actual risks are high) and to also 

minimize the occurrence of false 

positives for human health endpoints. 

We call this application of the 

TRIM.FaTE model TRIM-Screen. The 

facility-specific emission rates of POM 

were compared to the TRIM-Screen 

emission threshold values for POM to 

assess the potential for significant 

human health risks or environmental 

risks via non-inhalation pathways. 

5. Assessing Risks Considering 

Emissions Control Options 

In addition to assessing baseline 

inhalation risks and screening for 

potential multi-pathway risks, where 

appropriate, we also estimated risks 

considering the potential emission 

reductions that would be achieved by 

the particular control options under 

consideration. In these cases, the 

expected emissions reductions were 

applied to the specific HAP and 

emissions sources in the source category 

dataset to develop corresponding 

estimates of risk reductions. 

6. Conducting Other Risk-Related 

Analyses: Facility Wide Assessments 

To put the source category risks in 

context, for our residual risk reviews, 

we also typically examine the risks from 

the entire ‘‘facility,’’ where the facility 


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14Short-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. 

15U.S. EPA. National-Scale Air Toxics 

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

2001; page 85.) 

includes all HAP-emitting operations 

within a contiguous area and under 

common control. In these facility wide 

assessments 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. Eleven of the primary 

aluminum reduction plants are 

collocated with secondary aluminum 

production operations. Based on a 

general knowledge of these facilities, we 

believe that the Primary Aluminum 

sources are the largest sources of HAP 

emissions at each of them. Moreover, we 

plan to do a facility wide assessment for 

each of these eleven facilities in an 

upcoming RTR rulemaking for the 

Secondary Aluminum source category. 

Therefore, we did not perform a facility 

wide risk assessment for these eleven 

facilities as part of today’s action. For 

the four primary aluminum facilities 

that are not collocated with secondary 

aluminum production operations, the 

risk assessment performed as part of 

today’s action is a facility wide risk 

assessment. 

7. Considering Uncertainties in Risk 

Assessment 

Uncertainty and the potential for bias 

are inherent in all risk assessments, 

including those performed for the 

Primary Aluminum source category 

addressed in this proposal. Although 

uncertainty exists, we believe that our 

approach, which used conservative 

tools and assumptions, ensures that our 

decisions are health-protective. A brief 

discussion of the uncertainties in the 

emissions datasets, dispersion 

modeling, inhalation exposure estimates 

and dose-response relationships follows 

below. A more thorough discussion of 

these uncertainties is included in the 

risk assessment documentation 

(referenced earlier) available in the 

docket for this action. 

a. Uncertainties in the Emissions 

Datasets 

Although the development of the 

MACT 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 inaccurate, 

errors in estimating emissions values 

and other factors. The emission 

estimates considered in this analysis 

generally are annual totals for certain 

years that 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 a 

multiplication factor of 5 applied to the 

average annual hourly emission rate, 

which is intended to account for 

emission fluctuations due to normal 

facility operations. 

b. Uncertainties in Dispersion Modeling 

While the analysis employed the 

EPA’s recommended regulatory 

dispersion model, AERMOD, we 

recognize that there is uncertainty in 

ambient concentration estimates 

associated with any model, including 

AERMOD. In circumstances where we 

had to choose between various model 

options, where possible, model options 

(e.g., rural/urban, plume depletion, 

chemistry) were selected to provide an 

overestimate of ambient air 

concentrations of the HAP rather than 

underestimates. However, because of 

practicality and data limitation reasons, 

some factors (e.g., meteorology, building 

downwash) have the potential in some 

situations to overestimate or 

underestimate ambient impacts. For 

example, meteorological data were 

taken from a single year (1991), and 

facility locations can be a significant 

distance from the sites where these data 

were taken. Despite these uncertainties, 

we believe that at off-site locations and 

census block centroids, the approach 

considered in the dispersion modeling 

analysis should generally yield 

overestimates of ambient HAP 

concentrations. 

c. Uncertainties in Inhalation Exposure 

The effects of human mobility on 

exposures were not included in the 

assessment. Specifically, short-term 

mobility and long-term mobility 

between census blocks in the modeling 

domain were not considered.14 The 

assumption of not considering short or 

long-term population mobility does not 

bias the estimate of the theoretical MIR, 

nor does it affect the estimate of cancer 

incidence since 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 

risk levels. 

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 

further 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 it is an unbiased estimate of 

average risk and incidence. 

The assessments evaluate the cancer 

inhalation risks associated with 

continuous pollutant exposures over a 

70-year period, which is the assumed 

lifetime of an individual. In reality, both 

the length of time that modeled 

emissions 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 

United States facilities) will influence 

the risks posed by a given 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 rare cases, 

where a facility maintains or increases 

its emission levels beyond 70 years, 

residents live beyond 70 years at the 

same location, and the residents spend 

most of their days at that location, then 

the risks could potentially be 

underestimated. Annual cancer 

incidence estimates from exposures to 

emissions from these sources would not 

be affected by uncertainty in the length 

of time emissions sources operate. 

The exposure estimates used in these 

analyses assume chronic exposures to 

ambient 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, these levels are 

typically lower. This factor has the 

potential to result in an overstatement of 

25 to 30 percent of exposures.15

In addition to the uncertainties 

highlighted above, there are several 

other factors specific to the acute 

exposure assessment. The accuracy of 

an acute inhalation exposure assessment 

depends on the simultaneous 


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

help_gloss.htm). 

17An exception to this is the URE for benzene, 

which is considered to cover a range of values, each 

end of which is considered to be equally plausible 

and which is based on maximum likelihood 

estimates. 

18According to the NRC report, Science and 

Judgment in Risk Assessment (NRC, 1994) 

‘‘[Default] options are generic approaches, based on 

general scientific knowledge and policy judgment, 

that are applied to various elements of the risk 

assessment process when the correct scientific 

model is unknown or uncertain.’’ The 1983 NRC 

report, Risk Assessment in the Federal Government: 

Managing the Process, defined default option as 

‘‘the option chosen on the basis of risk assessment 

policy that appears to be the best choice in the 

absence of data to the contrary’’ (NRC, 1983a, p. 63). 

Therefore, default options are not rules that bind 

the Agency; rather, the Agency may depart from 

them in evaluating the risks posed by a specific 

substance when it believes this to be appropriate. 

In keeping with EPA’s goal of protecting public 

health and the environment, default assumptions 

are used to ensure that risk to chemicals is not 

underestimated (although defaults are not intended 

to overtly overestimate risk). See EPA, 2004, An 

Examination of EPA Risk Assessment Principles 

and Practices, EPA/100/B–04/001 available at: 

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

occurrence of independent factors that 

may vary greatly, such as hourly 

emissions rates, meteorology, and 

human activity patterns. In this 

assessment, we assume that individuals 

remain for 1 hour at the point of 

maximum ambient concentration as 

determined by the co-occurrence of 

peak emissions and worst-case 

meteorological conditions. These 

assumptions would tend to overestimate 

actual exposures since it is unlikely that 

a person would be located at the point 

of maximum exposure during the time 

of worst-case impact. 

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 noncancer 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 2005 Cancer 

Guidelines; namely, that ‘‘the primary 

goal of the EPA actions is protection of 

human health; accordingly, as an agency 

policy, risk assessment procedures, 

including default options that are used 

in the absence of scientific data to the 

contrary, should be health protective.’’ 

(EPA 2005 Cancer Guidelines, pages 1– 

7.) This is the approach followed here 

as summarized in the next several 

paragraphs. A complete detailed 

discussion of uncertainties and 

variability in dose-response 

relationships is given in the residual 

risk documentation, which is available 

in the docket for this action. 

Cancer URE values used in our risk 

assessments are those that have been 

developed to generally provide an upper 

bound estimate of risk. That is, they 

represent a ‘‘plausible upper limit to the 

true value of a quantity’’ (although this 

is usually not a true statistical 

confidence limit).16 In some 

circumstances, the true risk could be as 

low as zero; however, in other 

circumstances, the risk could also be 

greater.17 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 healthprotection, the EPA typically uses the 

upper bound estimates rather than 

lower bound or central tendency 

estimates in our risk assessments, an 

approach that may have limitations for 

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

expected benefits analysis). 

Chronic noncancer reference (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 daily 

oral exposure (RfD) or of a continuous 

inhalation exposure (RfC) 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 includes 

consideration of both uncertainty and 

variability. When there are gaps in the 

available information, UF are applied to 

derive reference values that are 

intended to protect against appreciable 

risk of deleterious effects. The UF are 

commonly default values,18 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 ‘‘uncertainty factor,’’ 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. 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 peer-reviewed reference values 

for cancer and noncancer effects for all 

pollutants emitted by the sources 

included in this assessment, some HAP 


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19Although 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. 

continue to have no reference values for 

cancer or chronic noncancer or acute 

effects. Since exposures to these 

pollutants cannot be included in a 

quantitative risk estimate, an 

understatement of risk for these 

pollutants at environmental exposure 

levels is possible. For a group of 

compounds that are either unspeciated 

or do not have reference values for every 

individual compound (e.g., glycol 

ethers), we conservatively use the most 

protective reference value to estimate 

risk from individual compounds in the 

group of compounds. 

Additionally, chronic reference values 

for several of the compounds included 

in this assessment are currently under 

the EPA IRIS review, and revised 

assessments may determine that these 

pollutants are more or less potent than 

the current value. We may re-evaluate 

residual risks for the final rulemaking if 

these reviews are completed prior to our 

taking final action for this source 

category and a dose-response metric 

changes enough to indicate that the risk 

assessment supporting this notice may 

significantly understate human health 

risk. 

e. Uncertainties in the Multi-Pathway 

and Environmental Effects Screening 

Assessment 

We generally assume that when 

exposure levels are not anticipated to 

adversely affect human health, they also 

are not anticipated to adversely affect 

the environment. For each source 

category, we generally rely on the sitespecific levels of PB–HAP emissions to 

determine whether a full assessment of 

the multi-pathway and environmental 

effects is necessary. For this source 

category, we only performed a multipathway screening assessment for PB– 

HAP. Thus, it is important to note that 

potential PB–HAP multi-pathway risks 

are biased high. 

C. How did we consider the risk results 

in making decisions for this proposal? 

In evaluating and developing 

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

discussed in section I.A of this 

preamble, 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) 19 of approximately 1-in-10 

thousand [i.e., 100-in-1 million]’’ (54 FR 

38045). In the second step of the 

process, the EPA sets the standard at a 

level that provides 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.) 

In past residual risk actions, the EPA 

has presented and considered a number 

of human health risk metrics associated 

with emissions from the category under 

review, including: The MIR; the 

numbers of persons in various risk 

ranges; cancer incidence; the maximum 

non-cancer hazard index (HI); and the 

maximum acute non-cancer hazard (72 

FR 25138, May 3, 2007; 71 FR 42724, 

July 27, 2006). In more recent proposals 

(75 FR 65068, October 21, 2010, and 75 

FR 80220, December 21, 2010), the EPA 

also presented and considered 

additional measures of health 

information, such as estimates of the 

risks associated with the maximum 

level of emissions which might be 

allowed by the current MACT standards 

(see, e.g., 75 FR 65068, October 21, 

2010, and 75 FR 80220, December 21, 

2010). The EPA also discussed and 

considered risk estimation 

uncertainties. The EPA is providing this 

same type of information in support of 

the proposed actions described in this 

Federal Register notice. 

The agency is considering all 

available health information to inform 

our determinations of risk acceptability 

and ample margin of safety under CAA 

section 112(f). Specifically, 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). 

Similarly, with regard to making the 

ample margin of safety determination, 

as stated in the Benzene NESHAP ‘‘[in 

the ample margin decision, 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 agency acknowledges that the 

Benzene NESHAP provides flexibility 

regarding what factors the EPA might 

consider in making determinations and 

how these factors might be weighed for 

each source category. In responding to 

comment on our policy under the 

Benzene NESHAP, the EPA explained 

that: ‘‘The policy chosen by the 

Administrator permits consideration of 

multiple measures of health risk. Not 

only can the MIR figure be considered, 

but also incidence, the presence of noncancer 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’ ’’ (54 FR 38057). 

Thus, the level of the MIR is only one 

factor to be weighed in determining 

acceptability of risks. The Benzene 

NESHAP explained that ‘‘an MIR of 

approximately 1-in-10 thousand should 

ordinarily be the upper end of the range 

of acceptability. As risks increase above 

this benchmark, they become 

presumptively less acceptable under 

CAA section 112, and would be 

weighed with the other health risk 

measures and information in making an 

overall judgment on acceptability. Or, 

the agency may find, in a particular 

case, that a risk that includes MIR less 

than the presumptively acceptable level 

is unacceptable in the light of other 

health risk factors’’ (Id. at 38045). 

Similarly, with regard to the ample 

margin of safety analysis, the EPA stated 

in the Benzene NESHAP that: ‘‘* * * 

the 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). 

D. 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 


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occurred since the Primary Aluminum 

Reduction Plant NESHAP was 

promulgated. 

Based on our analyses of the data and 

information collected from industry and 

the trade organization representing all 

facilities subject to the NESHAP, our 

general understanding of the industry, 

and other available information in the 

literature on potential controls for this 

industry, we identified no new 

developments in practices, processes, 

and control technologies. For the 

purpose of 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 1997 Primary Aluminum Reduction 

Plant NESHAP. 

• Any improvements in add-on 

control technology or other equipment 

(that were identified and considered 

during development of the 1997 Primary 

Aluminum Reduction Plant NESHAP) 

that could result in significant 

additional emissions reduction. 

• Any work practice or operational 

procedure that was not identified or 

considered during development of the 

1997 Primary Aluminum Reduction 

Plant NESHAP. 

• Any process change or pollution 

prevention alternative that could be 

broadly applied to the industry and that 

was not identified or considered during 

development of the 1997 Primary 

Aluminum Reduction Plant NESHAP. 

We also consulted the EPA’s RACT/ 

BACT/LAER Clearinghouse (RBLC) to 

identify potential technology advances. 

Control technologies classified as RACT 

(Reasonably Available Control 

Technology), BACT (Best Available 

Control Technology), or LAER (Lowest 

Achievable Emissions Rate) apply to 

stationary sources depending on 

whether the sources exist or new and on 

the size, age, and location of the facility. 

BACT and LAER (and sometimes RACT) 

are determined on a case-by-case basis, 

usually by State or local permitting 

agencies. The EPA established the RBLC 

to provide a central database of air 

pollution technology information 

(including technologies required in 

source-specific permits) to promote the 

sharing of information among 

permitting agencies and to aid in 

identifying future possible control 

technology options that might apply 

broadly to numerous sources within a 

category or apply only on a source-bysource basis. The RBLC contains over 

5,000 air pollution control permit 

determinations that can help identify 

appropriate technologies to mitigate 

many air pollutant emissions streams. 

We searched this database to determine 

whether it contained any practices, 

processes, or control technologies for 

the types of processes covered by the 

Primary Aluminum Reduction Plant 

NESHAP. No such practices, processes, 

or control technologies were identified 

in this database. 

E. What other issues are we addressing 

in this proposal? 

In addition to the analyses described 

above, we also reviewed other aspects of 

the MACT standards for possible 

revision as appropriate and necessary. 

Based on this review we have identified 

aspects of the MACT standards that we 

believe need revision. 

This includes proposing revisions to 

the startup, shutdown and malfunction 

(SSM) provisions of the MACT rule in 

order to ensure that they are consistent 

with a recent court decision in Sierra 

Club v. EPA, 551 F. 3d 1019 (DC Cir. 

2008). In addition, we are proposing 

other changes to the rule which are not 

based on residual risk. These include 

establishing MACT floor-based 

standards for POM emissions from 

prebake potlines, COS emissions from 

all potlines, and design standards for 

control of POM emissions from existing 

pitch storage tanks. We are also 

proposing changes to the rule related to 

affirmative defense for exceedance of an 

emission limit during a malfunction. 

The analyses and proposed decisions for 

these actions are presented in section IV 

of this preamble. 

IV. Analytical Results and Proposed 

Decisions 

This section of the preamble provides 

the results of our RTR for the Primary 

Aluminum Reduction Plant source 

category and our proposed decisions 

concerning changes to the Primary 

Aluminum Reduction Plant NESHAP. 

A. What are the results of our analyses 

and proposed decisions regarding 

unregulated emissions sources? 

The current MACT rule has no 

standards for POM from prebake 

potlines. Prebake facilities have 

significantly lower POM emissions 

compared to Soderberg facilities. 

Nevertheless, these emissions are not 

negligible. We are proposing to establish 

MACT emission limits for POM from 

prebake potlines in this action. The 

typical controls used on these prebake 

potlines to limit the primary (i.e., stack) 

emissions, and which reflect the MACT 

floor level of control, are dry alumina 

scrubbers (with a baghouse). We 

calculated MACT floor limits for these 

potlines based on the limited available 

data. We also considered possible 

controls beyond the MACT floor, such 

as wet roof scrubbers, but we estimated 

that these beyond-the-floor controls 

would only achieve approximately an 

additional 30 percent reduction in 

secondary (i.e., roof vent) emissions and 

that the costs of these additional 

controls would be quite high (e.g., well 

over $100 million in capital costs for the 

industry). We estimate that the cost of 

controlling POM from prebake potroom 

secondary emissions would be 

approximately $800,000 per ton. 

Therefore, we are proposing emission 

limits for POM from prebake potlines, 

after considering variability in 

emissions using a 99% upper prediction 

level approach, based on the MACT 

floor. We are proposing a POM emission 

limit for new prebake potlines equal to 

the lowest limit for existing prebake 

potlines (developed from data obtained 

from the best performing sources 

(center-worked prebake one) facilities). 

More details about the data and analyses 

used to derive the MACT limits, and 

explanation of the beyond-the-floor 

analyses, are provided in the technical 

document Draft MACT Floor Analysis 

for the Primary Aluminum Production 

Source Category which is available in 

the docket for this proposed action. The 

proposed limits for prebake potlines are 

shown in Table 5. 

TABLE 5—PROPOSED EMISSION LIMITS FOR NEW AND EXISTING PREBAKE POTLINES

Source Pollutant Emission limit 

Existing Prebake: 

CWPB1 potlines ................................................................... POM ............. 0.31 kg/Mg (0.62 lb/ton) of aluminum produced. 

CWPB2 potlines ................................................................... POM ............. 0.65 kg/Mg (1.3 lb/ton) of aluminum produced. 

CWPB3 potlines ................................................................... POM ............. 0.63 kg/Mg (1.26 lb/ton) of aluminum produced. 

SWPB potlines: .................................................................... POM ............. 0.33 kg/Mg (0.65 lb/ton) of aluminum produced. 

New Prebake: 


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TABLE 5—PROPOSED EMISSION LIMITS FOR NEW AND EXISTING PREBAKE POTLINES—Continued 

Source Pollutant Emission limit 

All prebake potline types ...................................................... POM ............. 0.31 kg/Mg (0.62 lb/ton) of aluminum produced. 

As mentioned above, the current 

MACT rule has no standards for COS. It 

is very difficult and quite expensive to 

measure total COS emissions because 

the concentrations of secondary 

emissions are below the detection limit 

of the EPA reference method. However, 

stack tests are feasible and have been 

completed. Moreover, emissions studies 

have been completed using an 

experimental test method to estimate 

COS emissions from these secondary 

emissions sources (Determination of 

COS to SO2 Ratio in Smelting Process 

Emissions at the Alcoa Warrick 

Operations, 4 August 1995). We have 

been able to use the experimental test 

results along with stack test data and 

data on sulfur content of input materials 

to estimate total COS emissions. We 

have determined that there is a direct 

relationship between the COS emissions 

and the sulfur content of raw materials. 

The results of these studies indicate that 

an estimated 8 percent of the sulfur 

present in the coke (used to make 

anodes) is converted to COS emissions. 

Given the technical difficulties of 

measuring secondary COS emissions 

directly, and given that there is a direct 

relationship between sulfur content of 

input materials and COS emissions, we 

developed a mass balance equation for 

calculating COS emissions. Using this 

approach, we developed a proposed 

MACT standard for COS using the mass 

balance equation. The equation derives 

monthly COS emission rates based on 

anode coke sulfur content, anode 

consumption and aluminum 

production, as follows: 

Where: 

ECOS = the facility wide 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 used at the facility 

during the calendar month; 

Z = the tons of aluminum produced at the 

facility during the calendar month; and 

%S = the weighted average sulfur content of 

the anode coke utilized in the 

production of aluminum during the 

calendar month (e.g., if the weighted 

average sulfur content of the anode coke 

utilized during the calendar month was 

2.5%, then %S = 0.025). 

Using this method, we are proposing 

a MACT floor limit for COS for existing 

facilities at 3.9 pounds of COS per ton 

of aluminum produced (lb/ton Al), 

based on data obtained from the five 

facilities with the lowest calculated COS 

emissions and adjustment to account for 

variability using a 99% upper 

prediction limit approach. With regard 

to costs for this standard, we estimate 

that all facilities will be able to meet 

this limit with minimal additional costs 

(e.g., calculating COS emissions and the 

associated monitoring, recordkeeping 

and reporting). With regard to new 

sources, the MACT floor limit for COS 

for new facilities is proposed at 3.1 lb 

COS/ton Al, based on data obtained 

from the facility with the lowest 

calculated COS emissions and 

adjustment to account for variability. 

We also considered beyond-the-floor 

options for COS. For example, we 

assessed the feasibility and costs of 

proposing that all existing facilities 

meet a limit of 3.1 lb COS/ton Al. We 

estimate that a limit at this level would 

impact 5 facilities, result in 220 tpy 

reductions of COS emissions, at a total 

cost of $13,000,000 (or $2.6 million per 

facility) per year. However, there are 

significant uncertainties regarding the 

future availability and costs of the 

associated lower-sulfur anode coke. The 

Primary Aluminum industry obtains 

most of their coke as a by-product from 

the gas and oil refinery industry. It is 

our understanding that currently 

available coke with low sulfur contents 

could be very hard to obtain in the 

future and will likely be much more 

expensive. This situation is expected 

due to the following: (1) The type of 

crude oil input at refineries in the future 

is generally expected to be heavier and, 

therefore, less likely to result in ‘‘anode 

grade coke’’ that has the structure 

necessary for use in anode production; 

(2) the type of crude oil input at 

refineries in the future is generally 

expected to have higher sulfur content 

because the per barrel cost of heavy sour 

(i.e., high-sulfur) crude oil is so much 

lower than light sweet (i.e., low-sulfur) 

crude oil; (3) refineries initially 

designed to process light sweet crude oil 

are being converted to process heavy 

sour crude oil at a rapid pace worldwide 

due to refinery economics; (4) refineries 

are designed to desulfurize the product 

streams (gasoline, diesel, etc.), not the 

crude oil input, and the sulfur in the 

crude oil tends to concentrate in the 

petroleum coke (i.e., the ‘‘bottoms’’); (5) 

unwillingness of refineries to 

preferentially process light sweet crude 

oil in place of heavy sour crude oil due 

to unfavorable economics (i.e., refineries 

will not modify their operations to 

change the quality of a by-product such 

as petroleum coke); and (6) the lack of 

leverage that primary aluminum 

companies have over the quality of this 

by-product, as coke is a very low profit 

item for refineries and anode grade coke 

represents less than 20% of all the 

petroleum coke produced worldwide. 

Thus, based on future availability of 

low-sulfur coke, the true long term costs 

could exceed the present estimated cost 

of $13,000,000 per year. 

We also evaluated the feasibility and 

costs of another beyond-the-floor option 

of requiring that all existing facilities 

meet a limit of 3.5 lb COS/ton Al. We 

estimate that a limit at this level would 

impact 2 facilities, result in 52 tpy 

reductions of COS emissions, at a total 

cost of $2,000,000 (or $1 million per 

facility) per year. Once again, these 

estimated costs could be significant 

underestimates of the true long-term 

costs. The uncertainties and concerns 

about the future availability and costs of 

the required low-sulfur content coke 

that are described above for the 3.1 lb 

COS/ton Al option are also a concern for 

this 3.5 lb COS/ton Al option. 

We also considered control options 

including incineration and scrubbing of 

COS. The cost of incineration would be 

quite high due to the volume (typically 

millions of cubic feet per minute) and 

the relatively low temperature of the 

exhaust stream (typically less than 200 

°F). Incineration also involves the 

disadvantage of the generation of sulfur 

dioxide and other pollutants. Similarly, 

the cost of scrubbers would be quite 

high and involve the disadvantage of 

generating a waste sludge stream. 

Given the analyses and conclusions 

described above, we are proposing a 

MACT standard for COS for existing 

facilities based on the MACT floor 

analysis, which is a limit of 3.9 lb COS/ 

ton Al. With regard to new sources, we 

are proposing a MACT standard for COS 

based on the MACT floor analysis, 

which is a limit of 3.1 lb COS/ton Al. 

With regard to POM emissions from 

pitch storage tanks, the 1997 NESHAP 

included MACT standards for new pitch 


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20Most all POM emitted by this source category 

are PAHs. 

21 Individual facility acute HQ values for all 

facilities can be found in Appendix 5, Table 4, of 

the risk assessment document that is included in 

the docket for this proposed rulemaking. Acute HQ 

storage tanks, which required a 95 

percent reduction in POM emissions. 

However, the 1997 NESHAP had no 

limits for existing storage tanks. We are 

proposing in today’s action that existing 

tanks will be subject to the same 

standard (i.e., minimum of 95 percent 

reduction of POM emissions). At least 

three facilities are currently achieving 

this level of control. We estimate that 

eight facilities would be affected by this 

standard and would need to add 

controls, at a total annualized cost of 

about $21,000 per facility. We also 

estimate that this would achieve 1.6 

tons reductions in POM emissions per 

year. 

A non-contact single stage, 

refrigerated, water cooled condenser 

system was considered as a beyond the 

floor option for POM from pitch storage 

tanks. However, we believe the 

associated cost (estimated at $184,000 

per year, per facility) is not justified by 

the incremental control of HAP 

(estimated at 0.081 tons per year for the 

industry). 

B. What are the results of the risk 

assessments? 

For the Primary Aluminum source 

category, we conducted an inhalation 

risk assessment for all HAP emitted. We 

also conducted multi-pathway screening 

analyses for PB–HAP emitted (i.e., 

POM). Results of the risk assessment are 

presented briefly below and in more 

detail in the residual risk 

documentation referenced in section III 

of this preamble, which is available in 

the docket for this action. 

Table 6 of this preamble provides an 

overall summary of the results of the 

inhalation risk assessment. 

TABLE 6—PRIMARY ALUMINUM REDUCTION PLANT INHALATION RISK ASSESSMENT RESULTS

Maximum individual cancer risk 

(in 1 million) 1

Estimated 

population 

at increased 

risk of 

cancer 

≥1-in-1 

million 

Estimated 

annual 

cancer 

incidence 

(cases per 

year) 

Maximum chronic non-cancer TOSHI 2

Worst-case 

maximum refined 

screening acute 

Based on actual emissions level non-cancer HQ 3

Based on 

allowable 

emissions 

level 4 5

Based on 

actual 

emissions 

level 

Based on 

allowable 

emissions 

level 

30 ........................................................................... 100 41,000 0.005 0.4 0.6 HQREL 10 (HF) 

HQAEGL-1

4 (HF) 

1Estimated maximum individual excess lifetime cancer risk due to HAP emissions from the source category. 

2 Maximum TOSHI. The target organ with the highest TOSHI for the primary aluminum source category is the skeletal system. 

3See section III.B of this preamble for explanations of acute dose-response values. 

4The facility with the highest MIR based on allowable emissions is the Columbia Falls facility. Notably, this facility has not operated in approximately 2 years and therefore, the EPA did not generate risk estimates (i.e., MIR, TOSHI, and acute screening values) based on actual emissions 

for this facility. 5The highest MIR based on allowable emissions from an operating facility is estimated to be up to 50 in one million, for the operating 

Soderberg facility. 

The results of the chronic inhalation 

cancer risk assessment indicate that, 

based on estimates of current actual 

emissions, the maximum individual 

lifetime cancer risk (MIR) could be up 

to 30 in one million, with emissions of 

POM 20 primarily from potline roof 

vents (secondary emissions) and anode 

bake furnaces driving these risks. The 

highest MIR of up to 30 in one million 

based on actual emissions is due to 

POM emissions from the one currently 

operating Soderberg facility. The highest 

MIR due to actual emissions from 

prebake facilities was estimated to be up 

to 20 in one million; the next highest 

MIR for an operating prebake facility is 

estimated to be up to 6 in one million. 

The total estimated cancer incidence 

from this source category based on 

actual emission levels is 0.005 excess 

cancer cases per year or one case in 

every 200 years, with emissions of POM 

contributing approximately 99 percent 

to this cancer incidence. In addition, we 

note that approximately 41,000 people 

are estimated to have cancer risks 

greater than 1 in one million, and 

approximately 900 people are estimated 

to have risks greater than 10 in one 

million. When considering the risks 

associated with MACT-allowable 

emissions, the MIR could be up to 100 

in one million if the Columbia Falls 

facility (a Soderberg type facility) were 

to resume its primary aluminum 

operations (see note 4 on Table 6). The 

MIR based on allowable emissions from 

the one currently operating Soderberg 

facility (Massena East facility) was up to 

50 in one million. The highest MIR 

based on allowable emissions from any 

of the prebake facilities was up to 30 in 

one million. 

The maximum modeled chronic noncancer TOSHI value is 0.4 based on 

actual emissions, driven primarily by 

HF emissions. When considering MACT 

allowable emissions, the maximum 

chronic non-cancer TOSHI value could 

be up to 0.6. For this source category, 

there were two HAP that had relevant 

acute health effect screening values: 

Carbonyl sulfide (COS) and hydrofluoric 

acid (HF). Acute health effect screening 

is performed using actual emissions 

data. The Columbia Falls facility has not 

operated in about 2 years and has not 

operated at capacity since about 1999. 

Therefore, suitable actual emission data 

was not available for this facility and its 

acute health effects are not included in 

this discussion. Further, the carbon-only 

prebake anode production facility does 

not emit COS or HF. Therefore, this 

discussion addresses the acute health 

effects of only the 13 remaining 

facilities subject to this NESHAP. With 

respect to COS, we did not find any 

potential for acute health concerns for 

the 13 facilities based on their actual 

emissions. However, HF emissions did 

not screen out with respect to potential 

acute health effects. The highest refined 

worst-case HQ for HF based on a REL 

is 10, based on an AEGL-1 is 4, and 

based on an ERPG-1 is 2. Moreover, 8 

of the 13 facilities show the potential for 

worst-case acute HQ values greater than 

1 based on the REL, 4 of the 13 facilities 

show the potential for worst-case acute 

HQ values greater than 1 based on the 

AEGL-1 and 4 of the 13 facilities show 

the potential for worst-case acute HQ 

values greater than or equal to 1 based 

on the ERPG-1.21 Nevertheless, it is 


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values exceeding a value of 1 based on the REL 

were as follows: 10, 10, 9, 9, 5, 3, 2 and 2. Acute 

HQ values greater than a value of 1 based on the 

AEGL-1 were as follows: 4, 4, 3 and 3. Acute HQ 

values greater than or equal to a value of 1 based 

on the ERPG-1 were as follows: 2, 2, 1 and 1. 

important to note that all the worst-case 

acute HQs are based on conservative 

assumptions (e.g., worst-case 

meteorology coinciding with peak shortterm one-hour emissions from each 

emission point, with a person located at 

the point of maximum concentration 

during that hour). 

In addition to the analyses presented 

above, to screen for potential multipathway effects from emissions of POM, 

we compared the estimated actual PAH 

emission rates from 14 facilities in this 

source category to the multi-pathway 

screening rate for PAHs described in 

section III.B. Results of this worst-case 

screen estimate that actual PAH 

emissions from all 14 facilities exceed 

the PAH multi-pathway screening rate. 

With respect to these exceedances of the 

worst-case multi-pathway screening rate 

for PAHs, we note that this only 

indicates the potential for multipathway-related cancer risks of concern 

from PAHs. Moreover, due to data 

limitations, we were not able to refine 

our multi-pathway analysis beyond the 

screening assessment. Thus, we note 

that these results are biased high for 

purposes of screening and are subject to 

significant uncertainties. As such, they 

do not necessarily indicate that multipathway risks from POM are significant, 

only that we cannot rule out the 

possibility that they might be 

significant. 

C. What are our proposed decisions 

regarding risk acceptability and ample 

margin of safety? 

1. Risk Acceptability 

As noted in section III.C of this 

preamble, we weigh all health risk 

factors in our risk acceptability 

determination, including the MIR, the 

numbers of persons in various risk 

ranges, cancer incidence, the maximum 

noncancer HI, the maximum acute 

noncancer hazard, the extent of 

noncancer risks, the potential for 

adverse environmental effects, 

distribution of risks in the exposed 

population, and risk estimation 

uncertainties (54 FR 38044, September 

14, 1989). 

For the Primary Aluminum Reduction 

source category, the risk analysis we 

performed indicates that the cancer risk 

to the individual most exposed due to 

actual emissions is well below 100 in 

one million, and the cancer incidence is 

low (1 case in every 200 years). The 

potential risks due to allowable 

emissions are higher with an estimated 

MIR of up to 100 in one million which 

is the presumptive upper limit of 

acceptable risk. 

With regard to noncancer risks, the 

analysis indicates that chronic 

noncancer health risks are negligible 

due to both actual and allowable 

emissions. The assessment of potential 

acute noncancer effects (described in 

the previous section) suggests that there 

may be potential for some acute risks 

due to HF emissions with worst-case 

HQs up to 10 (based on the REL). In 

characterizing the potential for acute 

noncancer impacts of concern, it is 

important to remember the upward bias 

of these worst-case exposure estimates 

and to consider the results along with 

the rather large uncertainties related to 

the emissions estimates and screening 

methodology. 

With regard to multi-pathway 

exposures and risks, results of the 

screening analysis indicate that actual 

PAH emissions from all the facilities 

exceed the worst-case multi-pathway 

screening rate for PAHs, indicating the 

potential for possible multi-pathwayrelated cancer risks of concern from 

PAHs. We note that these screening 

results do not necessarily indicate that 

significant multi-pathway risks actually 

exist at primary aluminum facilities, 

only that we cannot rule them out as a 

possibility. 

Overall, in determining whether risk 

is acceptable, we considered all the 

available health risk information, as 

described above. In this case, because 

the MIRs due to actual emissions are 

well below 100-in-1 million risk, and 

since the one facility that could pose 

possible risks due to allowable 

emissions of up to 100 in one million 

is not operating, and because a number 

of other factors indicate relatively low 

risk concern (e.g., low cancer incidence 

and low potential for chronic noncancer 

risks), and given the conservative, 

worst-case screening level 

characteristics of the acute and multipathway assessments, and various 

uncertainties, we are proposing to 

determine that the risks due to HAP 

emissions from this source category are 

acceptable. 

2. Ample Margin of Safety Analysis 

We next considered whether the 

existing MACT standard provides an 

ample margin of safety (AMOS). Under 

the ample margin of safety analysis, we 

evaluate the cost and feasibility of 

available control technologies and other 

measures (including the controls, 

measures and costs reviewed under the 

technology review) that could be 

applied in this source category to 

further reduce the risks (or potential 

risks) due to emissions of HAP 

identified in our risk assessment, along 

with all of the health risks and other 

health information considered in the 

risk acceptability determination 

described above. 

First, we evaluated the feasibility to 

reduce the potential risks due to 

allowable POM emissions from 

Soderberg facilities. As described above, 

the potential cancer MIR from Soderberg 

facilities is estimated to be up to 100 in 

one million due to allowable emissions. 

These risks are driven by POM 

emissions from a Soderberg facility 

within the vertical stud Soderberg 

(VSS2) subcategory. The current 

emissions limit (from the 2005 NESHAP 

amendments) for POM from potlines in 

this VSS2 subcategory is 2.85 kg of POM 

per Mg of Aluminum produced (2.85 kg/ 

Mg, or 5.7 lbs/ton). Based on sitespecific emissions data submitted by the 

company in early 2008 for this facility, 

the estimated actual emissions from this 

facility were about 2 lbs/ton during the 

most recent years of operation (see 

Document EPA–HQ–OAR–2002–0031– 

0029, which is available in the docket 

for this rulemaking). 

After considering variability in 

emissions, which is appropriate for 

establishing MACT limits (as described 

in section III.A above), we calculated, 

using a 99% upper prediction level 

approach, that an emissions limit of 3.8 

lbs/ton could be achieved by this 

facility without any additional controls 

and therefore no additional costs. This 

would result in a reduction of 

approximately 33 percent for the 

allowable emissions from VSS2 

potlines, and would reduce the 

potential cancer MIR due to allowable 

emissions to about 70 in one million. 

We also evaluated potential controls to 

reduce these risks further (such as 

requiring wet roof scrubbers). We 

determined that these controls would be 

quite costly (approximately $4 million 

per ton of organic HAP), with estimated 

capital costs of about $40 million for 

this facility, and would only achieve 

about an additional 9.6 tons of HAP per 

year (30 percent) reduction in POM 

emissions. These controls and costs are 

described in more detail below. 

We also evaluated the POM emissions 

from the one operating Soderberg 

facility (which is in the HSS 

subcategory) as part of our AMOS 

analyses. Based on the risk assessment, 

we estimated that this facility posed a 

cancer MIR of up to 30 in one million 

based on actual emissions and an MIR 

of up to 50 in one million based on 

allowable emissions. The current 


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emissions limit for POM from potlines 

for this HSS subcategory is 2.35 kg/Mg 

(or 4.7 lbs/ton). Based on site specific 

emissions data for this facility, the 

actual emissions from this facility are 

estimated to be about 1.5 lbs/ton. After 

considering variability in emissions, we 

determined that an emissions limit of 

3.0 lbs/ton could be achieved by this 

facility with no additional controls and, 

therefore, no additional costs. This 

would result in a reduction of 

approximately 36 percent for the 

allowable emissions from these HSS 

potlines, and would reduce the 

potential cancer MIR due to allowable 

emissions from this facility to about 30 

in one million. 

We identified wet roof scrubbers as 

one possible control technology that 

could be applied to further reduce 

allowable and actual emissions of POM 

from potlines, to reduce the cancer risks 

due to actual and allowable POM 

emissions, and to reduce the potential 

risks due to multi-pathway exposures to 

POM. One facility in the source category 

currently has this type of scrubber. 

These controls can also be used to 

reduce HF emissions and, thus, would 

reduce the potential for acute noncancer 

risks. However, the costs for these 

controls are high. For example, we 

estimate that the capital costs for the 

typical facility would be more than $40 

million, with annualized costs of $13 

million. Industry wide this would result 

in total capital costs of over $400 

million, with estimated annualized 

costs of over $150 million. These 

controls would achieve reductions of 

secondary emissions of about 30 to 50 

percent. Given the high costs (estimated 

at approximately $140,000 per ton of 

HAP) and relatively low emissions and 

risk reductions, we propose that it is not 

appropriate or necessary to establish 

these additional controls under 

112(f)(2). Therefore, based our AMOS 

analysis, we are proposing under 

section 112(f)(2) of the CAA to lower the 

POM emissions limit for VSS2 potlines 

from 5.7 to 3.8 lbs/ton and to lower the 

POM limit for HSS potlines from 4.7 to 

3.0 lbs/ton. Pursuant to CAA section 

112(f)(4), we are proposing that these 

changes apply 90 days after the effective 

date of this rulemaking. We did not 

identify any other cost-effective controls 

to further reduce HAP emissions for this 

source category under the AMOS 

analyses. 

In accordance with the approach 

established in the Benzene NESHAP, 

the EPA weighed all health risk 

measures and information considered in 

the risk acceptability determination, 

along with the costs and economic 

impacts of emissions controls, 

technological feasibility, uncertainties 

and other relevant factors in proposing 

our ample margin of safety 

determination. Considering the health 

risk information and the costs of the 

options identified, we propose that the 

existing MACT standards, along with 

the proposed lower POM limits for 

potlines at Soderberg facilities (VSS2 

and HSS subcategories) described 

above, will provide an ample margin of 

safety to protect public health. 

Pursuant to CAA section 112(f)(4), we 

are proposing that these changes (i.e., 

lower emission limits for potlines at 

Soderberg facilities) apply 90 days after 

the effective date of this rulemaking. See 

CAA section 112(f)(4)(A). 

Nevertheless, we solicit comment and 

information on the feasibility, costs and 

appropriateness of any additional 

controls or options to further reduce the 

potential risks due to emissions of HAP, 

especially POM and HF. 

D. What are the results and proposed 

decisions based on our technology 

review? 

As described above, dry alumina 

scrubbers (with baghouses) are the 

typical controls used to minimize 

primary emissions of HF and POM from 

the potlines. However, some facilities 

use wet scrubbers and ESPs to control 

these emissions. The MACT control 

technology typically used for anode 

bake furnaces is also a dry alumina 

scrubber, and a capture system vented 

to a dry coke scrubber is used for 

control of paste production plants. 

These facilities further reduce HAP 

emissions from anode bake furnaces by 

implementation of certain practices 

during periods of startup (e.g., 

development of an anode bake furnace 

startup schedule, operation of the 

associated control system(s) within 

normal parametric limits prior to the 

startup of the anode bake furnace). To 

further control potline secondary 

emissions, one facility has wet roof 

scrubbers to get additional control of HF 

and POM. As described in the AMOS 

section above, it would be quite costly 

to require wet roof scrubbers on other 

facilities. 

Overall, based on our technology 

review, we determined that there have 

been no developments in practices, 

processes, and control technologies that 

would be considered feasible and costeffective to apply to this source category 

since promulgation of the Primary 

Aluminum Reduction Plant NESHAP, 

other than the anode bake furnace 

startup practices mentioned above. We 

propose to modify the MACT 

requirements for anode bake furnaces to 

include implementation of the startup 

practices mentioned above. Further, 

based on an analysis of recent emissions 

data, we believe that the practices, 

processes and control technologies 

currently in use by this source category 

allow for a reduction in the POM 

emission limits for Soderberg potlines 

(please refer to the ample margin of 

safety analysis in section IV.C.2 of this 

preamble). 

Additional details regarding these 

analyses can be found in the following 

technical document for this action 

which is available in the docket: Draft 

Technology Review for the Primary 

Aluminum Reduction Plant Source 

Category. 

E. What other actions are we proposing? 

1. Startup, Shutdown and Malfunctions 

The United States Court of Appeals 

for the District of Columbia Circuit 

vacated portions of two provisions in 

the EPA’s CAA section 112 regulations 

governing the emissions of HAP during 

periods of startup, shutdown and 

malfunction (SSM). Sierra Club v. EPA, 

551 F.3d 1019 (DC Cir. 2008), cert. 

denied, 130 S. Ct. 1735 (U.S. 2010). 

Specifically, the Court vacated the SSM 

exemption contained in 40 CFR 

63.6(f)(1) and 40 CFR 63.6(h)(1), that are 

part of a regulation, commonly referred 

to as the ‘‘General Provisions Rule,’’ that 

the EPA promulgated under CAA 

section 112. When incorporated into 

CAA section 112(d) regulations for 

specific source categories, these two 

provisions exempt sources from the 

requirement to comply with the 

otherwise applicable CAA section 

112(d) emissions standard during 

periods of SSM. 

We are proposing the elimination of 

the SSM exemption in this rule. 

Consistent with Sierra Club v. EPA, the 

EPA is proposing standards in this rule 

that apply at all times. We are also 

proposing several revisions to Appendix 

A to subpart LL of part 63 (the General 

Provisions Applicability table). For 

example, we are proposing to eliminate 

the incorporation of the General 

Provisions’ requirement that the source 

develop an SSM plan. We also are 

proposing to eliminate or revise certain 

recordkeeping and reporting 

requirements related to the SSM 

exemption. The EPA has attempted to 

ensure that we have not included in the 

proposed regulatory language any 

provisions that are inappropriate, 

unnecessary, or redundant in the 

absence of the SSM exemption. We are 

specifically seeking comment on 

whether there are any such provisions 

that we have inadvertently incorporated 

or overlooked. 


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In proposing the standards in this 

rule, the EPA has taken into account 

startup and shutdown periods and, for 

the reasons explained below, the EPA is 

proposing in some cases different 

standards for startup periods. 

The 1997 MACT rule allowed for 

periods of up to six months for startup 

of existing potlines that had been 

previously shutdown. These long 

startup periods for potlines are 

recognized as part of the normal 

operations during which emissions 

testing is not feasible. The current 

MACT emission limits are not 

applicable during these startup periods. 

Thus, we are proposing MACT 

standards for these periods in today’s 

action. Given that it is economically and 

technically infeasible to measure 

emissions during these startup periods, 

we are proposing detailed work practice 

standards that will minimize HAP 

emissions and ensure proper operation 

of the processes and control equipment 

during startup periods. The proposed 

work practices include bringing the 

potline scrubbers and exhaust fans on 

line prior to energizing the first cell 

being restarted, ensuring that the 

primary capture and control system is 

operating at all times during startup, 

and keeping pots covered during startup 

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. Moreover, 

facilities must inspect potlines daily 

during startup and perform additional 

work practices, including resealing pot 

crust as often and as soon as practicable, 

reducing cell temperatures to as low as 

practicable, and adjusting pot 

parameters to their optimum levels to 

include, but not limited to, the 

following parameters: Alumina addition 

rate, exhaust air flow, cell voltage, 

feeding level, anode current, and liquid 

and solid bath levels. 

The 1997 MACT rule allowed for 

startup periods for new or reconstructed 

anode bake furnaces and pitch storage 

tanks and for anode bake furnaces that 

had been previously shutdown. Based 

on information received from industry, 

we believe that these sources can 

comply with their MACT standards 

during startup periods. Therefore, we 

are removing the provisions for startup 

of anode bake furnaces and pitch storage 

tanks. However, we have added startup 

practices for anode bake furnace startup 

periods to help ensure that the 

standards will be met. These startup 

practices will minimize HAP emissions 

and ensure proper operation of the 

processes and control equipment during 

startup periods (please refer to the 

discussion of the technology review in 

section IV.D of this preamble). 

Shutdown emissions are not expected 

to be different from those during normal 

operation; therefore, no separate 

standard or work practice is warranted. 

We propose that the numerical MACT 

limits described in previous sections of 

this preamble (established for normal 

operations) will apply during shutdown 

periods. We also propose that the MACT 

limits for all other affected units besides 

potlines (bake furnaces, pitch tanks, and 

paste production plants) apply at all 

times, including during startups and 

shutdowns. 

Information on periods of startup and 

shutdown received from the industry 

indicate that emissions during startup 

(except for potlines) and shutdown 

periods are no greater than emissions 

during normal operations. Therefore, 

the continued operation of the existing 

control devices and emission capture 

systems will, in conjunction with the 

detailed proposed startup practices and 

work practices described above, be 

consistent with maximum achievable 

control technology and will be 

adequate, along with all the other 

standards described above, to ensure 

that risks will be acceptable and the rule 

will provide an ample margin of safety. 

Periods of startup, normal operations, 

and shutdown are all predictable and 

routine aspects of a source’s operations. 

However, by contrast, malfunction is 

defined as a ‘‘sudden, infrequent, and 

not reasonably preventable failure of air 

pollution control and monitoring 

equipment, process equipment or a 

process to operate in a normal or usual 

manner * * *’’ (40 CFR 63.2). The EPA 

has determined that CAA section 112 

does not require that emissions that 

occur during periods of malfunction 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 emissions 

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 or best controlled sources 

when setting emissions standards. 

Moreover, while the EPA accounts for 

variability in setting emissions 

standards consistent with the CAA 

section 112 case law, nothing in that 

case law requires the agency to consider 

malfunctions as part of that analysis. 

Section 112 of the CAA uses the concept 

of ‘‘best controlled’’ and ‘‘best 

performing’’ unit in defining the level of 

stringency that CAA section 112 

performance standards must meet. 

Applying the concept of ‘‘best 

controlled’’ or ‘‘best performing’’ to a 

unit that is malfunctioning presents 

significant difficulties, as malfunctions 

are sudden and unexpected events. 

Further, accounting for malfunctions 

would be difficult, if not impossible, 

given the myriad different types of 

malfunctions that can occur across all 

sources in the category and given the 

difficulties associated with predicting or 

accounting for the frequency, degree, 

and duration of various malfunctions 

that might occur. As such, the 

performance of units that are 

malfunctioning is not ‘‘reasonably’’ 

foreseeable. See, e.g., Sierra Club v. 

EPA, 167 F.3d 658, 662 (DC Cir. 1999) 

(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 (DC Cir. 

1978) (‘‘In the nature of things, no 

general limit, individual permit, or even 

any upset provision can anticipate all 

upset situations. After a certain point, 

the transgression of regulatory limits 

caused by ‘uncontrollable acts of third 

parties,’ such as strikes, sabotage, 

operator intoxication or insanity, and a 

variety of other eventualities, must be a 

matter for the administrative exercise of 

case-by-case enforcement discretion, not 

for specification in advance by 

regulation’’). In addition, the goal of a 

best controlled or best performing 

source is to operate in such a way as to 

avoid malfunctions of the source, and 

accounting for malfunctions could lead 

to standards that are significantly less 

stringent than levels that are achieved 

by a well-performing nonmalfunctioning source. 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) 


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standard was, in fact, ‘‘sudden, 

infrequent, not reasonably preventable’’ 

and was not instead ‘‘caused in part by 

poor maintenance or careless operation’’ 

40 CFR 63.2 (definition of malfunction). 

Finally, the EPA recognizes that even 

equipment that is properly designed and 

maintained can sometimes fail and that 

such failure can sometimes cause an 

exceedance of the relevant emissions 

standard. (See, e.g., State 

Implementation Plans: Policy Regarding 

Excessive Emissions During 

Malfunctions, Startup, and Shutdown 

(Sept. 20, 1999); Policy on Excess 

Emissions During Startup, Shutdown, 

Maintenance, and Malfunctions (Feb. 

15, 1983).). The EPA is therefore 

proposing to add to the final rule an 

affirmative defense to civil penalties for 

exceedances of emissions limits that are 

caused by malfunctions. See 40 CFR 

63.842 (defining ‘‘affirmative defense’’ 

to mean, in the context of an 

enforcement proceeding, a response or 

defense put forward by a defendant, 

regarding which the defendant has the 

burden of proof, and the merits of which 

are independently and objectively 

evaluated in a judicial or administrative 

proceeding). We also are proposing 

other regulatory provisions to specify 

the elements that are necessary to 

establish this affirmative defense; the 

source must prove by a preponderance 

of the evidence that it has met all of the 

elements set forth in 40 CFR 63.855 (see 

also 40 CFR 22.24). The criteria ensure 

that the affirmative defense is available 

only where the event that causes an 

exceedance of the emissions limit meets 

the narrow definition of malfunction in 

40 CFR 63.2 (sudden, infrequent, not 

reasonably preventable and not caused 

by poor maintenance and or careless 

operation). For example, to successfully 

assert the affirmative defense, the source 

must prove by a preponderance of the 

evidence that excess emissions ‘‘[w]ere 

caused by a sudden, infrequent, and 

unavoidable failure of air pollution 

control and monitoring equipment, 

process equipment, or a process to 

operate in a normal or usual manner 

* * *.’’ The criteria also are designed to 

ensure that steps are taken to correct the 

malfunction, to minimize emissions in 

accordance with 40 CFR sections 

63.843(f) and 63.844(f) to prevent future 

malfunctions. For example, the source 

must prove by a preponderance of the 

evidence that ‘‘[r]epairs were made as 

expeditiously as possible when the 

applicable emissions limitations were 

being exceeded * * *’’ and that ‘‘[a]ll 

possible steps were taken to minimize 

the impact of the excess emissions on 

ambient air quality, the environment 

and human health * * *.’’ In any 

judicial or administrative proceeding, 

the Administrator may challenge the 

assertion of the affirmative defense and, 

if the respondent has not met its burden 

of proving all of the requirements in the 

affirmative defense, appropriate 

penalties may be assessed in accordance 

with CAA section 113 (see also 40 CFR 

22.27). 

The EPA included an affirmative 

defense in the proposed rule in an 

attempt to balance a tension, inherent in 

many types of air regulation, to ensure 

adequate compliance while 

simultaneously recognizing that despite 

the most diligent of efforts, emission 

limits may be exceeded under 

circumstances beyond the control of the 

source. The EPA must establish 

emission standards that ‘‘limit the 

quantity, rate, or concentration of 

emissions of air pollutants on a 

continuous basis.’’ 42 U.S.C. 7602(k) 

(defining ‘‘emission limitation and 

emission standard’’). See generally 

Sierra Club v. EPA, 551 F.3d 1019, 1021 

(DC Cir. 2008). Thus, the EPA is 

required to ensure that section 112 

emissions limitations are continuous. 

The affirmative defense for malfunction 

events meets this requirement by 

ensuring that even where there is a 

malfunction, the emission limitation is 

still enforceable through injunctive 

relief. While ‘‘continuous’’ limitations, 

on the one hand, are required, there is 

also case law indicating that in many 

situations it is appropriate for EPA to 

account for the practical realities of 

technology. For example, in Essex 

Chemical v. Ruckelshaus, 486 F.2d 427, 

433 (DC Cir. 1973), the DC Circuit 

acknowledged that in setting standards 

under CAA section 111 ‘‘variant 

provisions’’ such as provisions allowing 

for upsets during startup, shutdown and 

equipment malfunction ‘‘appear 

necessary to preserve the reasonableness 

of the standards as a whole and that the 

record does not support the ‘never to be 

exceeded’ standard currently in force.’’ 

See also, Portland Cement Association 

v. Ruckelshaus, 486 F.2d 375 (DC Cir. 

1973). Though intervening case law 

such as Sierra Club v. EPA and the CAA 

1977 amendments undermine the 

relevance of these cases today, they 

support the EPA’s view that a system 

that incorporates some level of 

flexibility is reasonable. The affirmative 

defense simply provides for a defense to 

civil penalties for excess emissions that 

are proven to be beyond the control of 

the source. By incorporating an 

affirmative defense, the EPA has 

formalized its approach to upset events. 

In a Clean Water Act setting, the Ninth 

Circuit required this type of formalized 

approach when regulating ‘‘upsets 

beyond the control of the permit 

holder.’’ Marathon Oil Co. v. EPA, 564 

F.2d 1253, 1272–73 (9th Cir. 1977). But 

see, Weyerhaeuser Co. v. Costle, 590 

F.2d 1011, 1057–58 (DC Cir. 1978) 

(holding that an informal approach is 

adequate). The affirmative defense 

provisions give the EPA the flexibility to 

both ensure that its emission limitations 

are ‘‘continuous’’ as required by 42 

U.S.C. 7602(k), and account for 

unplanned upsets and thus support the 

reasonableness of the standard as a 

whole. 

Specifically, we are proposing the 

following rule changes: 

• Add general duty requirements in 

40 CFR sections 63.843 and 63.844 to 

replace General Provision requirements 

that reference vacated SSM provisions. 

• Add replacement language that 

eliminates the reference to SSM 

exemptions applicable to performance 

tests in 40 CFR section 63.847(d). 

• Add paragraphs in 40 CFR section 

63.850(d) requiring the reporting of 

malfunctions as part of the affirmative 

defense provisions. 

• Add paragraphs in 40 CFR section 

63.850(e) requiring the keeping of 

certain records during malfunctions as 

part of the affirmative defense 

provisions. 

• Revise Appendix A to subpart LL of 

part 63 to reflect changes in the 

applicability of the General Provisions 

to this subpart resulting from a court 

vacatur of certain SSM requirements in 

the General Provisions. 

2. Electronic Reporting 

The EPA must have performance test 

data to conduct effective reviews of 

CAA sections 112 and 129 standards, as 

well as for many other purposes 

including compliance determinations, 

emissions factor development, and 

annual emissions rate determinations. 

In conducting these required reviews, 

the EPA has found it ineffective and 

time consuming, not only for us, but 

also for regulatory agencies and source 

owners and operators, to locate, collect, 

and submit performance test data 

because of varied locations for data 

storage and varied data storage methods. 

In recent years, though, stack testing 

firms have typically collected 

performance test data in electronic 

format, making it possible to move to an 

electronic data submittal system that 

would increase the ease and efficiency 

of data submittal and improve data 

accessibility. 

Through this proposal the EPA is 

presenting a step to increase the ease 

and efficiency of data submittal and 


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improve data accessibility. Specifically, 

the EPA is proposing that owners and 

operators of Primary Aluminum 

Reduction Plant facilities submit 

electronic copies of required 

performance test reports to the EPA’s 

WebFIRE database. The WebFIRE 

database was constructed to store 

performance test data for use in 

developing emissions factors. A 

description of the WebFIRE database is 

available at http://cfpub.epa.gov/ 

oarweb/index.cfm?action=fire.main. 

As proposed above, data entry would 

be through an electronic emissions test 

report structure called the Electronic 

Reporting Tool. The ERT would be able 

to transmit the electronic report through 

the EPA’s Central Data Exchange 

network for storage in the WebFIRE 

database making submittal of data very 

straightforward and easy. A description 

of the ERT can be found at http:// 

www.epa.gov/ttn/chief/ert/ert_tool.html. 

The proposal to submit performance 

test data electronically to the EPA 

would apply only to those performance 

tests conducted using test methods that 

will be supported by the ERT. The ERT 

contains a specific electronic data entry 

form for most of the commonly used 

EPA reference methods. A listing of the 

pollutants and test methods supported 

by the ERT is available at http:// 

www.epa.gov/ttn/chief/ert/ert_tool.html. 

We believe that industry would benefit 

from this proposed approach to 

electronic data submittal. Having these 

data, the EPA would be able to develop 

improved emissions factors, make fewer 

information requests, and promulgate 

better informed regulations. 

One major advantage of the proposed 

submittal of performance test data 

through the ERT is a standardized 

method to compile and store much of 

the documentation required to be 

reported by this rule. Another advantage 

is that the ERT clearly states what 

testing information would be required. 

Another important proposed benefit of 

submitting these data to the EPA at the 

time the source test is conducted is that 

it should substantially reduce the effort 

involved in data collection activities in 

the future. When the EPA has 

performance test data in hand, there 

will likely be fewer or less substantial 

data collection requests in conjunction 

with prospective required residual risk 

assessments or technology reviews. This 

would result in a reduced burden on 

both affected facilities (in terms of 

reduced manpower to respond to data 

collection requests) and the EPA (in 

terms of preparing and distributing data 

collection requests and assessing the 

results). 

State, local, and Tribal agencies could 

also benefit from more streamlined and 

accurate review of electronic data 

submitted to them. The ERT would 

allow for an electronic review process 

rather than a manual data assessment 

making review and evaluation of the 

source provided data and calculations 

easier and more efficient. Finally, 

another benefit of the proposed data 

submittal to WebFIRE electronically is 

that these data would greatly improve 

the overall quality of existing and new 

emissions factors by supplementing the 

pool of emissions test data for 

establishing emissions factors and by 

ensuring that the factors are more 

representative of current industry 

operational procedures. A common 

complaint heard from industry and 

regulators is that emissions factors are 

outdated or not representative of a 

particular source category. With timely 

receipt and incorporation of data from 

most performance tests, the EPA would 

be able to ensure that emissions factors, 

when updated, represent the most 

current range of operational practices. In 

summary, in addition to supporting 

regulation development, control strategy 

development, and other air pollution 

control activities, having an electronic 

database populated with performance 

test data would save industry, state, 

local, Tribal agencies, and the EPA 

significant time, money, and effort 

while also improving the quality of 

emissions inventories and, as a result, 

air quality regulations. 

Records must be maintained in a form 

suitable and readily available for 

expeditious review, according to 

63.10(b)(1). Electronic recordkeeping 

and reporting is available for many 

records, and is the form considered 

most suitable for expeditious review if 

available. Electronic recordkeeping and 

reporting is encouraged in this proposal 

and some records and reports are 

required to be kept in electronic format. 

F. Compliance Dates 

We are proposing that existing 

facilities must comply with the 

proposed revised emissions limits for 

Soderberg potlines (which are being 

proposed under CAA sections 112(f)(2) 

for all affected sources), no later than 90 

days after the date of publication of the 

final rule. We are proposing that 

existing facilities must comply with all 

other changes proposed in this action 

(other than affirmative defense 

provisions and electronic reporting 

which are effective upon promulgation 

of the final rule) no later than 3 years 

after the date of publication of the final 

rule. All new or reconstructed facilities 

must comply with all requirements in 

this rule upon startup. 

V. Summary of 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 production plants. 

B. What are the air quality impacts? 

The proposed rule will require the 

POM emissions from existing 

uncontrolled pitch storage tanks to be 

reduced by a minimum of 95 percent. 

This is estimated to result in a reduction 

of 1.6 tons per year (tpy) of POM. In 

addition, the proposed lower Soderberg 

potline POM limits would reduce POM 

emissions from the two Soderberg 

facilities, assuming production at plant 

capacity, by approximately 300 tpy, 

combined. 

C. What are the cost impacts? 

Under the proposed amendments, 8 

facilities would be required to install or 

upgrade, and operate emissions control 

systems (such as activated carbon 

adsorbers or condensers) to control 

emissions of HAP from pitch storage 

tanks at total estimated cost of $167,832 

per year, or $20,979 per facility. In 

addition, 12 facilities will have to 

conduct periodic performance tests for 

POM emissions from 45 prebake 

potlines at an estimated total cost of 

$90,000 per year for the source category, 

or $7,500 per year per facility. The total 

estimated cost of the rule is $258,000 

per year. 

D. What are the economic impacts? 

We performed an economic impact 

analysis for the proposed modifications 

in this rulemaking. That analysis 

estimates total annualized costs of 

approximately $257,832 at 13 facilities 

and cost to revenue of less than 0.02% 

for the Primary Aluminum Production 

source category. For more information, 

please refer to the Draft Economic 

Impact Analysis for this proposed 

rulemaking that is available in the 

public docket for this proposed 

rulemaking. 

E. What are the benefits? 

This proposed rule will achieve about 

1.6 tons per year reductions in POM 

emissions, which may result in a slight 

health benefit. The proposed limits of 

3.9 pounds of COS per ton of aluminum 

produced (lb COS/ton Al) for existing 

facilities and 3.1 lb COS/ton Al for new 


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facilities will prevent increases in COS 

emissions and prevent increases in SO2

emissions as a co-benefit. The proposed 

COS standard will likely result in the 

use of lower sulfur content coke in the 

anode production processes. This 

reduction in anode coke sulfur content 

would result in decreases in emissions 

of both COS and sulfur dioxide (SO2). 

We estimate that SO2 emissions will 

decrease by 12 tons for each ton of COS 

reduction. 

VI. Request for Comments 

We are soliciting comments on all 

aspects of this proposed action. In 

addition to general comments on this 

proposed action, we are also interested 

in any additional data that may help to 

reduce the uncertainties inherent in the 

risk assessments and other analyses. We 

are specifically interested in receiving 

corrections to the site-specific emissions 

profiles used for risk modeling. Such 

data should include supporting 

documentation in sufficient detail to 

allow characterization of the quality and 

representativeness of the data or 

information. Section VII of this 

preamble provides more information on 

submitting data. 

VII. Submitting Data Corrections 

The site-specific emissions profiles 

used in the source category risk and 

demographic analyses are available for 

download on the RTR Web page at: 

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

rtrpg.html. The data files include 

detailed information for each HAP 

emissions release point for the facility 

included 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 Web page, 

complete the following steps: 

1. Within this downloaded file, enter 

suggested revisions to the data fields 

appropriate for that information. The 

data fields that may be revised include 

the following: 

Data element Definition 

Control Measure ................................................................. Are control measures in place? (yes or no) 

Control Measure Comment ................................................ Select control measure from list provided, and briefly describe the control measure. 

Delete ................................................................................. Indicate here if the facility or record should be deleted. 

Delete Comment ................................................................ Describes the reason for deletion. 

Emissions Calculation Method Code for Revised Emissions.Code description of the method used to derive emissions. For example, CEM, material balance, stack test, etc. 

Emissions Process Group .................................................. Enter the general type of emissions process associated with the specified emissions 

point. 

Fugitive Angle .................................................................... Enter release angle (clockwise from true North); orientation of the y-dimension relative to true North, measured positive for clockwise starting at 0 degrees (maximum 89 degrees). 

Fugitive Length ................................................................... Enter dimension of the source in the east-west (x-) direction, commonly referred to 

as length (ft). 

Fugitive Width .................................................................... Enter dimension of the source in the north-south (y-) direction, commonly referred to 

as width (ft). 

Malfunction Emissions ....................................................... Enter total annual emissions due to malfunctions (tpy). 

Malfunction Emissions Max Hourly .................................... Enter maximum hourly malfunction emissions here (lb/hr). 

North American Datum ...................................................... Enter datum for latitude/longitude coordinates (NAD27 or NAD83); if left blank, 

NAD83 is assumed. 

Process Comment .............................................................. Enter general comments about process sources of emissions. 

REVISED Address ............................................................. Enter revised physical street address for MACT facility here. 

REVISED City .................................................................... Enter revised city name here. 

REVISED County Name .................................................... Enter revised county name here. 

REVISED Emissions Release Point Type ......................... Enter revised Emissions Release Point Type here. 

REVISED End Date ........................................................... Enter revised End Date here. 

REVISED Exit Gas Flow Rate ........................................... Enter revised Exit Gas Flowrate here (ft3/sec). 

REVISED Exit Gas Temperature ....................................... Enter revised Exit Gas Temperature here (F). 

REVISED Exit Gas Velocity ............................................... Enter revised Exit Gas Velocity here (ft/sec). 

REVISED Facility Category Code ...................................... Enter revised Facility Category Code here, which indicates whether facility is a major 

or area source. 

REVISED Facility Name .................................................... Enter revised Facility Name here. 

REVISED Facility Registry Identifier .................................. Enter revised Facility Registry Identifier here, which is an ID assigned by the EPA 

Facility Registry System. 

REVISED HAP Emissions Performance Level Code ........ Enter revised HAP Emissions Performance Level here. 

REVISED Latitude .............................................................. Enter revised Latitude here (decimal degrees). 

REVISED Longitude ........................................................... Enter revised Longitude here (decimal degrees). 

REVISED MACT Code ...................................................... Enter revised MACT Code here. 

REVISED Pollutant Code ................................................... Enter revised Pollutant Code here. 

REVISED Routine Emissions ............................................ Enter revised routine emissions value here (tpy). 

REVISED SCC Code ......................................................... Enter revised SCC Code here. 

REVISED Stack Diameter .................................................. Enter revised Stack Diameter here (ft). 

REVISED Stack Height ...................................................... Enter revised Stack Height here (ft). 

REVISED Start Date .......................................................... Enter revised Start Date here. 

REVISED State .................................................................. Enter revised State here. 

REVISED Tribal Code ........................................................ Enter revised Tribal Code here. 

REVISED Zip Code ............................................................ Enter revised Zip Code here. 

Shutdown Emissions .......................................................... Enter total annual emissions due to shutdown events (tpy). 

Shutdown Emissions Max Hourly ...................................... Enter maximum hourly shutdown emissions here (lb/hr). 

Stack Comment .................................................................. Enter general comments about emissions release points. 

Startup Emissions .............................................................. Enter total annual emissions due to startup events (tpy). 

Startup Emissions Max Hourly ........................................... Enter maximum hourly startup emissions here (lb/hr). 


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Data element Definition 

Year Closed ....................................................................... Enter date facility stopped operations. 

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). 

4. Send the entire downloaded file 

with suggested revisions in Microsoft® 

Access format and all accompanying 

documentation to Docket ID Number 

EPA–HQ–OAR–2011–0797 (through one 

of the methods described in the 

ADDRESSES section of this preamble). To 

expedite review of the revisions, it 

would also be helpful if you submitted 

a copy of your revisions to the EPA 

directly at RTR@epa.gov in addition to 

submitting them to the docket. 

5. If you are providing comments on 

a facility, you need only submit one file 

for that facility, which 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® Access files, 

which are provided on the RTR Web 

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

rrisk/rtrpg.html. 

VIII. Statutory and Executive Order 

Reviews 

A. Executive Order 12866: Regulatory 

Planning and Review and Executive 

Order 13563: Improving Regulation and 

Regulatory Review 

Under Executive Order 12866 (58 FR 

51735, October 4, 1993), this action is a 

significant regulatory action because it 

raises novel legal and policy issues. 

Accordingly, the EPA submitted this 

action to the Office of Management and 

Budget (OMB) for review under 

Executive Orders 12866 and 13563 (76 

FR 3821, January 21, 2011) and any 

changes made in response to OMB 

recommendations have been 

documented in the docket for this 

action. 

B. Paperwork Reduction Act 

The information collection 

requirements in this rule have been 

submitted for approval to the Office of 

Management and Budget (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 the EPA ICR 

number 2447.01. The information 

collection requirements are not 

enforceable until OMB approves them. 

The information requirements are based 

on notification, recordkeeping, and 

reporting requirements in the NESHAP 

General Provisions (40 CFR part 63, 

subpart A), which are mandatory for all 

operators subject to national emissions 

standards. These recordkeeping and 

reporting requirements are specifically 

authorized by CAA section 114 (42 

U.S.C. 7414). All information submitted 

to the EPA pursuant to the 

recordkeeping and reporting 

requirements for which a claim of 

confidentiality is made is safeguarded 

according to agency policies set forth in 

40 CFR part 2, subpart B. 

We are proposing new paperwork 

requirements for the Primary Aluminum 

Reduction Plant source category in the 

form of a one-time requirement to 

prepare design specifications for 

existing pitch storage tank controls, and 

submissions of test reports and 

calculations for demonstration of 

compliance with prebake potline POM 

limits. 

For this proposed rule, the EPA is 

adding affirmative defense to the 

estimate of burden in the ICR. To 

provide the public with an estimate of 

the relative magnitude of the burden 

associated with an assertion of the 

affirmative defense position adopted by 

a source, the EPA has provided 

administrative adjustments to this ICR 

to show what the notification, 

recordkeeping and reporting 

requirements associated with the 

assertion of the affirmative defense 

might entail. The EPA’s estimate for the 

required notification, reports and 

records for any individual incident, 

including the root cause analysis, totals 

$3,141 and is based on the time and 

effort required of a source to review 

relevant data, interview plant 

employees, and document the events 

surrounding a malfunction that has 

caused an exceedance of an emissions 

limit. The estimate also includes time to 

produce and retain the record and 

reports for submission to the EPA. The 

EPA provides this illustrative estimate 

of this burden because these costs are 

only incurred if there has been a 

violation and a source chooses to take 

advantage of the affirmative defense. 

Given the variety of circumstances 

under which malfunctions could occur, 

as well as differences among sources’ 

operation and maintenance practices, 

we cannot reliably predict the severity 

and frequency of malfunction-related 

excess emissions events for a particular 

source. It is important to note that the 

EPA has no basis currently for 

estimating the number of malfunctions 

that would qualify for an affirmative 

defense. Current historical records 

would be an inappropriate basis, as 

source owners or operators previously 

operated their facilities in recognition 

that they were exempt from the 

requirement to comply with emissions 

standards during malfunctions. Of the 

number of excess emissions events 

reported by source operators, only a 

small number would be expected to 

result from a malfunction (based on the 

definition above), and only a subset of 

excess emissions caused by 

malfunctions would result in the source 

choosing to assert the affirmative 

defense. Thus we believe the number of 

instances in which source operators 

might be expected to avail themselves of 

the affirmative defense will be 

extremely small. 

With respect to the Primary 

Aluminum Production source category, 

the emissions controls are operational 

before the associated emission source(s) 

commence operation and remain 

operational until after the associated 

emission source(s) cease operation. 

Also, production operations would not 

proceed or continue if there is a 

malfunction of a control device and the 

time required to shut down production 

operations (i.e., on the order of a day) 

is small compared to the averaging time 

of the emission standards (i.e., monthly, 

quarterly and annual averages). Thus, 

we believe it is unlikely that a control 

device malfunction would cause an 

exceedance of any emission limit. 

Therefore, sources within this source 

category are not expected to have any 

need or use for the affirmative defense 

and we believe that there is no burden 

to the industry for the affirmative 

defense provisions in the proposed rule. 

We expect to gather information on 

such events in the future and will revise 

this estimate as better information 

becomes available. We estimate 15 

regulated entities are currently subject 

to subpart LL and will be subject to all 

proposed standards. The annual 

monitoring, reporting, and 

recordkeeping burden for this collection 

(averaged over the first 3 years after the 

effective date of the standards) for these 

amendments to subpart LL is estimated 


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to be $148,000 per year. This includes 

1,558 labor hours per year at a total 

labor cost of $148,000 per year, and total 

non-labor capital and operation and 

maintenance (O&M) costs of $500 per 

year. This estimate includes 

performance tests, notifications, 

reporting, and recordkeeping associated 

with the new requirements for existing 

pitch storage tanks and new and 

existing potlines. The total burden for 

the Federal government (averaged over 

the first 3 years after the effective date 

of the standard) is estimated to be 120 

hours per year at a total labor cost of 

$11,400 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. When 

these ICRs are approved by OMB, the 

agency will publish a technical 

amendment to 40 CFR part 9 in the 

Federal Register to display the OMB 

control numbers for the approved 

information collection requirements 

contained in the final rules. 

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 number EPA–HQ–OAR–2011–0797. 

Submit any comments related to the ICR 

to the EPA and OMB. See the ADDRESSES

section at the beginning of this notice 

for where to submit comments to the 

EPA. Send comments to OMB at the 

Office of Information and Regulatory 

Affairs, Office of Management and 

Budget, 725 17th Street, NW., 

Washington, DC 20503, Attention: Desk 

Office for the EPA. Since OMB is 

required to make a decision concerning 

the ICR between 30 and 60 days after 

December 6, 2011, a comment to OMB 

is best assured of having its full effect 

if OMB receives it by January 5, 2012. 

The final rule will respond to any OMB 

or public comments on the information 

collection requirements contained in 

this proposal. 

C. Regulatory Flexibility Act 

The Regulatory Flexibility Act (RFA) 

generally requires an agency to prepare 

a regulatory flexibility analysis of any 

rule subject to notice and comment 

rulemaking requirements under the 

Administrative Procedure Act or any 

other statute unless the agency certifies 

that the rule will not have a significant 

economic impact on a substantial 

number of small entities. Small entities 

include small businesses, small 

organizations, and small governmental 

jurisdictions. 

For purposes of assessing the impacts 

of this proposed 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-forprofit 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 employees according 

to the SBA small business standards 

definitions. There are no small entities 

subject to subpart LL. 

After considering the economic 

impacts of today’s proposed rule on 

small entities, I certify that this action 

will not have a significant economic 

impact on a substantial number of small 

entities. This proposed rule will not 

impose any requirements on small 

entities. We continue to be interested in 

the potential impacts of the proposed 

rule on small entities and welcome 

comment on issues related to such 

impacts. 

D. Unfunded Mandates Reform Act 

This proposed rule 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 

proposed rule 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. The proposed rule imposes no 

enforceable duties on any State, local or 

Tribal governments or the private sector. 

Thus, this proposed rule is not subject 

to the requirements of sections 202 or 

205 of the UMRA. 

This proposed rule 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 

because it contains no requirements that 

apply to such governments nor does it 

impose obligations upon them. 

E. Executive Order 13132: Federalism 

This proposed rule 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 proposed rule will 

supersede State regulations. Thus, 

Executive Order 13132 does not apply 

to this proposed rule. 

In the spirit of Executive Order 13132, 

and consistent with the EPA policy to 

promote communications between the 

EPA and State and local governments, 

the EPA specifically solicits comment 

on this proposed rule from State and 

local officials. 

F. Executive Order 13175: Consultation 

and Coordination With Indian Tribal 

Governments 

This proposed rule does not have 

Tribal implications, as specified in 

Executive Order 13175 (65 FR 67249, 

November 9, 2000). None of the 

provisions of this proposed rule will 

result in increased emissions of any 

hazardous air pollutant from any 

facility. The more stringent limitations 

of POM emissions from horizontal stud 

Soderberg potlines may result in 

decreased risk to Indian Tribal 

populations. Thus, Executive Order 

13175 does not apply to this action. 

The EPA specifically solicits 

additional comment on this proposed 

action from Tribal officials. 

G. Executive Order 13045: Protection of 

Children From Environmental Health 

Risks and Safety Risks 

This proposed rule is not subject to 

Executive Order 13045 (62 FR 19885, 

April 23, 1997) because it is not 

economically significant as defined in 

Executive Order 12866. Moreover, the 

agency does not believe the 

environmental health risks or safety 

risks addressed by this action present a 

disproportionate risk to children. 

Nevertheless, the public is invited to 

submit comments or identify studies 

and data that assess effects of early life 

exposure to HAP from Primary 

Aluminum sources. The EPA will 

typically accord greater weight to 

studies and data that have been peer 

reviewed. 

H. Executive Order 13211: Actions 

Concerning Regulations That 

Significantly Affect Energy Supply, 

Distribution, or Use 

This action is not a ‘‘significant 

energy action’’ as defined under 

Executive Order 13211, ‘‘Actions 

Concerning Regulations That 


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Significantly Affect Energy Supply, 

Distribution, or Use’’ (66 FR 28355, May 

22, 2001), because it is not likely to have 

significant adverse effect on the supply, 

distribution, or use of energy. This 

action will not create any new 

requirements and therefore no 

additional costs for sources in the 

energy supply, distribution, or use 

sectors. 

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 voluntary 

consensus standards bodies. 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 EPA proposes 

to use ASTM D3177–02 (2007) Standard 

Test Methods for Total Sulfur in the 

Analysis Sample of Coal and Coke. This 

is a voluntary consensus method. This 

method can be obtained from the 

American Society for Testing and 

Materials, 100 Bar Harbor Drive, West 

Conshohocken, Pennsylvania 19428 

(telephone number (610) 832–9500). 

This method was proposed because it is 

commonly used by primary aluminum 

reduction facilities to demonstrate 

compliance with sulfur dioxide 

emission limitations imposed in their 

current Title V permits. The EPA 

welcomes comments on this aspect of 

this proposed rulemaking and, 

specifically, invites the public to 

identify potentially-applicable 

voluntary consensus standards 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 source 

category, 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 not appreciably reduce these risks 

further. As a result, this proposed rule 

will not have disproportionately high 

and adverse human health or 

environmental effects on minority or 

low-income populations. 

To examine the potential for any 

environmental justice issues that might 

be associated with each 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 rule are 

described in the document Draft 

Residual Risk Assessment for the 

Primary Aluminum Reduction Plant 

Source Category which may be found in 

the docket for this rulemaking. The 

development of demographic analyses 

to inform the consideration of 

environmental justice issues in the EPA 

rulemakings is an evolving science. The 

EPA offers the demographic analyses in 

today’s proposed rulemaking as 

examples of how such analyses might be 

developed to inform such consideration, 

and invites public comment on the 

approaches used and the interpretations 

made from the results, with the hope 

that this will support the refinement 

and improve utility of such analyses. 

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 one 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 Draft 

Residual Risk Assessment for the 

Primary Aluminum Reduction Plant 

Source Category in the docket for this 

proposed 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 4, 2011. 

Lisa P. Jackson, 

Administrator. 

For the reasons stated in the 

preamble, part 63 of title 40, chapter I, 

of the Code of Federal Regulations is 

proposed to be amended as follows: 

PART 63—[AMENDED] 

1. The authority citation for part 63 

continues to read as follows: 

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

Subpart LL—[AMENDED] 

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 

adding paragraph (a)(3) to read as 

follows: 

§ 63.841 Incorporation by reference. 

(a) * * * 

(3) ASTM D3177–02 (2007) Standard 

Test Methods for Total Sulfur in the 

Analysis Sample of Coal and Coke. 

* * * * * 

4. Section 63.842 is amended to read 

as follows: 

a. Removing the definition for 

‘‘Vertical stud Soderberg one (VSS1)’’ 

and 

b. Adding, in alphabetical order, 

definitions for ‘‘Affirmative defense’’ 

and ‘‘Startup of an anode bake furnace’’ 

§ 63.842 Definitions. 

* * * * * 

Affirmative defense means, in the 

context of an enforcement proceeding, a 

response or defense put forward by a 

defendant, regarding which the 

defendant has the burden of proof, and 

the merits of which are independently 

and objectively evaluated in a judicial 

or administrative proceeding. 

* * * * * 

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 or 


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re-start concludes at the start of the 

second anode bake cycle. 

* * * * * 

5. Section 63.843 is amended to read 

as follows: 

a. Revising paragraph 

(a)(1)introductory text; 

b. Removing and reserving paragraph 

(a)(1)(v); 

c. Revising paragraph 

(a)(2)introductory text, and (a)(2)(i); 

d. Removing and reserving paragraph 

(a)(2)(ii); 

e. Revising paragraph (a)(2)(iii); and 

f. Adding paragraphs (a)(2)(iv) 

through (a)(2)(vii), (d), (e), and (f) 

§ 63.843 Emission limits for existing 

sources. 

(a) * * * 

(1) Emissions of TF must not exceed: 

* * * * * 

(v) [Reserved] 

* * * * * 

(2) Emissions of POM must not 

exceed: 

(i) 1.5 kg/Mg (3.0 lb/ton) of aluminum 

produced for each HSS potline; 

(ii) [Reserved;] 

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

aluminum produced for each VSS2 

potline; 

(iv) 0.31 kg/Mg (0.62 lb/ton) of 

aluminum produced for each existing 

CWPB1 prebake potline; 

(v) 0.65 kg/Mg (1.3 lb/ton) of 

aluminum produced for each existing 

CWPB2 prebake potline; 

(vi) 0.63 kg/Mg (1.26 lb/ton) of 

aluminum produced for each existing 

CWPB3 prebake potline; 

(vii) 0.33 kg/Mg (0.65 lb/ton) of 

aluminum produced for each existing 

SWPB prebake potline; 

* * * * * 

(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 3.9 lb/ton of aluminum 

produced. 

(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 to read 

as follows: 

a. Adding paragraph (a)(3); 

b. Adding paragraph (e); and 

c. Adding paragraph (f) 

§ 63.844 Emission limits for new or 

reconstructed sources. 

(a) * * * 

(3) POM limit. Emissions of POM from 

prebake potlines must not exceed 0.31 

kg/Mg (0.62 lb/ton) of aluminum 

produced. 

* * * * * 

(e) COS limit. Emissions of COS must 

not exceed 3.1 lb/ton of aluminum 

produced. 

(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 to read 

as follows: 

a. Revising paragraph (b); 

b. Revising paragraph (d)(2)(iv); 

c. Revising paragraphs (d)(4)(ii) and 

(iii); 

d. Removing and reserving paragraph 

(d)(4)(iv); and 

e. Adding paragraphs (e) and (f) 

§ 63.846 Emission averaging. 

* * * * * 

(b) Soderberg Potlines. The owner or 

operator may average TF emissions from 

potlines and demonstrate compliance 

with the limits in Table 1 of this subpart 

using the procedures in paragraphs 

(b)(1) and (b)(2) of this section. The 

owner or operator also may average 

POM emissions from potlines and 

demonstrate compliance with the limits 

in Table 2 of this subpart using the 

procedures in paragraphs (b)(1) and 

(b)(3) of this section. 

* * * * * 

(d) * * * 

(2) * * * 

(iv) The test plan for the measurement 

of TF or POM emissions in accordance 

with the requirements in §§ 63.847(b) 

and (k); 

* * * * * 

(4) * * * 

(ii) The inclusion of any emission 

source other than an existing potline or 

existing anode bake furnace 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. 

(iv) [Reserved] 

* * * * * 

(e) TF emissions from Prebake 

Potlines. The owner or operator may 

average TF emissions from potlines and 

demonstrate compliance with the limits 

in Table 1 of this subpart using the 

procedures in paragraphs (e)(1) and 

(e)(2) of this section. 

(1) Monthly average emissions of TF 

must not exceed the applicable emission 

limit in Table 1 of this subpart. The 

emission rate must be calculated based 

on the total emissions from all potlines 

over the period divided by the quantity 

of aluminum produced during the 

period, from all potlines comprising the 

averaging group. 

(2) To determine compliance with the 

applicable emission limit in Table 1 of 

this subpart for TF emissions, the owner 

or operator must determine the monthly 

average emissions (in lb/ton) from each 

potline from at least three runs per 

potline each month for TF secondary 

emissions using the procedures and 

methods in §§ 63.847 and 63.849. The 

owner or operator must combine the 

results of secondary TF monthly average 

emissions with the TF results for the 

primary control system and divide total 

emissions by total aluminum 

production. 

(f) POM Emissions from Prebake 

Potlines. The owner or operator also 

may average POM emissions from 

potlines and demonstrate compliance 

with the limits in Table 2 of this subpart 

using the procedures in paragraphs (f)(1) 

and (f)(2) of this section. 

(1) Average emissions of POM for 

each compliance demonstration period, 

must not exceed the applicable emission 

limit in Table 2 of this subpart. The 

emission rate must be calculated based 

on the total emissions from all potlines 

divided by the quantity of aluminum 

produced during the period, from all 

potlines comprising the averaging 

group. 

(2) To determine compliance with the 

applicable emission limit in Table 2 of 

this subpart for POM emissions, the 

owner or operator must determine the 

emissions (in lb/ton) from each potline 

using the procedures and methods in 

§§ 63.847 and 63.849. The owner or 

operator must combine the results of 

measured or calculated secondary POM 

emissions with the POM emissions from 

the primary control system and divide 


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total emissions by total aluminum 

production. 

8. Section 63.847 is amended to read 

as follows: 

a. Revising paragraph (a) 

b. Removing and reserving paragraph 

(a)(3); 

c. Revising paragraph (b) introductory 

text; 

d. Removing and reserving paragraph 

(b)(6); 

e. Revising paragraphs (c)(1); (c)(2); 

and (c)(3); 

f. Removing paragraphs (c)(2)(i) 

through (iii); 

g. Revising paragraph (c)(3); 

h. Revising paragraphs (d) 

introductory text and (d)(2); 

i. Adding paragraph (d)(5); 

j. Revising paragraph (e)(2); 

k. Adding paragraph (e)(8); 

l. Revising paragraph (g) introductory 

text; 

m. Adding and reserving paragraph 

(i); and 

n. 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 

reduction plant must comply with the 

requirements of this subpart by the 

applicable compliance date in 

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

section: 

(1) Except as noted in paragraph (a)(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 90 days after date of 

publication of final rule] for Soderberg 

potlines subject to emission limits in 

§§ 63.843(a)(2)(i) and (iii) which became 

effective [Date of publication of final 

rule]. 

(ii) [Date 3 years after date of 

publication of final rule] for prebake 

potlines subject to emission limits in 

§§ 63.843(a)(2)(iv) through (vii) and 

§ 63.848(n) which became effective 

[Date of publication of final rule]. 

(iii) [Date 3 years after date of 

publication of final rule] for potlines 

subject to the work practice standards in 

§ 63.854 which became effective [insert 

date of publication of final rule]. 

(iv) [Date 3 years after date of 

publication of final rule] for anode bake 

furnaces subject to the startup practices 

in § 63.847(m) which became effective 

[insert date of publication of final rule]. 

(v) [Date 3 years after date of 

publication of final rule] for compliance 

with the pitch storage tank POM limit 

provisions of § 63.843(d) and the COS 

emission limit provisions of §§ 63.843(e) 

and 63.844(e). 

(vi) [Date of publication of final rule] 

for the malfunction provisions of 

§§ 63.850(d)(2) and (e)(4)(xvi) and (xvii), 

the affirmative defense provisions of 

§ 63.855, and the electronic reporting 

provisions of §§ 63.850(c) and (f). 

(3) [Reserved] 

* * * * * 

(b) Test plan for TF from all anode 

bake furnaces and potlines and POM 

from Soderberg potlines. The owner or 

operator shall prepare a site-specific test 

plan prior to the initial performance test 

according to the requirements of 

§ 63.7(c) of this part. The test plan must 

include procedures for conducting the 

initial performance test and for 

subsequent performance tests required 

in § 63.848 for emission monitoring. In 

addition to the information required by 

§ 63.7, the test plan shall include: 

* * * * * 

(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. 

* * * * * 

(2) POM emissions from Soderberg 

potlines. For each Soderberg (HSS and 

VSS2) potline, the owner or operator 

must measure and record the emission 

rate of POM exiting the primary 

emission control system 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)(2) of this section, the 

owner or operator must compute and 

record the average of at least three runs 

each quarter (one run per month) 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 POM is equal to or less 

than the applicable emission limit in 

§§ 63.843, 63.844 or 63.846. 

* * * * * 

(5) POM emissions from prebake 

potlines. For each prebake potline, the 

owner or operator shall measure and 

record the emission rate of POM exiting 

the primary emission control system. 

The owner or operator shall compute 

and record the average of at least three 

runs every five years. For each prebake 

potline for which the owner or operator 

chooses to demonstrate compliance 

using the provisions of § 63.847(e)(2), 

the owner or operator shall measure and 

record the emission rate of secondary 

emissions exiting through each roof 

monitor, or for a plant with roof 

scrubbers, exiting through the scrubbers. 

The owner or operator shall compute 

and record the average of at least three 

runs every five years for secondary 

emissions. The owner or operator shall 

calculate POM emissions in accordance 

with §§ 63.847(e)(2) or (8). Compliance 

is demonstrated when the emission rate 

of POM is equal to or less than the 

applicable emission limit in §§ 63.843, 

63.844 or 63.846. 

(e) * * * 

(2) Compute the emission rate of POM 

from each Soderberg potline, and from 

those prebake potlines for which the 

owner or operator chooses to measure 

secondary emissions, using Equation 1, 

Where: 

Ep = emission rate of POM from the potline, 

kg/mg (lb/ton); and 

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

dscf). POM emission data collected during 

the installation and startup of a cathode 

must not be included in Cs. 

* * * * * 

(8) Compute the rate of POM from 

each prebake potline for which the 

owner or operator does not choose to 

determine the measure the secondary 

emissions using Equation 3: 


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Where: 

Epp = emission rate of POM from a potline, 

kg/Mg (lb/ton); 

Cpp1 = concentration of POM from the 

primary control system, mg/dscm (mg/ 

dscf); 

Q1 = volumetric flow rate of effluent gas from 

the primary control system dscm/hr 

(dscf/hr); 

CpF2 = concentration of TF from the 

secondary control system or roof 

monitor, mg/dscm (mg/dscf); 

CpF1 = concentration of TF from the primary 

control system, mg/dscm (mg/dscf); and 

Q2 = volumetric flow rate of effluent gas from 

the secondary control system or roof 

monitor, dscm/hr (dscf/hr). 

* * * * * 

(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 

shall 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. 

* * * * * 

(i) [Reserved] 

(j) COS Emissions. The owner 

operator of each plant must calculate 

the facility wide emission rate of COS 

for each calendar month of operation 

using the following equation: 

Where: 

ECOS = the facility wide 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 used at the facility 

during the calendar month; 

Z = the tons of aluminum produced at the 

facility during the calendar month; and 

%S = the weighted average sulfur content of 

the anode coke utilized in the 

production of aluminum during the 

calendar month (e.g., if the weighted 

average sulfur content of the anode coke 

utilized during the calendar month was 

2.5%, then %S = 0.025). 

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) Test plan POM from prebake 

potlines. The owner or operator must 

prepare a site-specific test plan prior to 

the initial performance test according to 

the requirements of § 63.7(c) of this part. 

The test plan must include procedures 

for conducting the initial performance 

test and for subsequent performance 

tests required in § 63.848 for emission 

monitoring. In addition to the 

information required by § 63.7 the test 

plan shall include: 

(1) Procedures to ensure a minimum 

of three runs are performed for the 

primary control system for each source; 

(2) For a source with a single control 

device exhausted through multiple 

stacks, procedures to ensure that at least 

three runs are performed by a 

representative sample of the stacks 

satisfactory to the applicable regulatory 

authority; 

(3) For multiple control devices on a 

single source, procedures to ensure that 

at least one run is performed for each 

control device by a representative 

sample of the stacks satisfactory to the 

applicable regulatory authority; 

(4) For plants with roof scrubbers, 

procedures for rotating sampling among 

the scrubbers or other procedures to 

obtain representative samples as 

approved by the applicable regulatory 

authority. 

(l) Potlines. The owner or operator 

shall 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 

applicable regulatory authority. 

(m) Anode bake furnaces. If you own 

or operate a new or existing primary 

aluminum reduction affected source, 

you must develop a written startup plan 

as described in paragraphs (m)(1) 

through (4) of this section. Compliance 

with the startup plan will be 

demonstrated through site inspection(s) 

and review of site records by the 

applicable 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 

prior to startup of the first anode bake 

furnace. 

(2) Records of time, date, duration 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 first 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. 

9. Section 63.848 is amended by 

revising paragraph (b) and adding 

paragraph (n) to read as follows: 

§ 63.848 Emission monitoring 

requirements. 

* * * * * 

(b) POM emissions from Soderberg 

potlines. Using the procedures in 

§ 63.847 and in the approved test plan, 

the owner or operator shall monitor 

emissions of POM from each Soderberg 

(HSS and VSS2) potline every three 

months. The owner or operator shall 

compute and record the quarterly (3- 

month) average from at least one run per 

month for secondary emissions and the 

previous 12-month average of all runs 

for the primary control systems to 

determine compliance with the 

applicable emission limit. The owner or 

operator must include all valid runs in 

the quarterly (3-month) 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. 

* * * * * 

(n) POM emissions from prebake 

potlines. Using the procedures in 

§ 63.847 and in the approved test plan, 

the owner or operator must monitor 

emissions of POM from each prebake 

potline every five years. The owner or 

operator must compute and record the 

sum of the average primary and 

secondary emissions using the 

procedures of §§ 63.847(e)(2) or (e)(8). 

10. Section 63.849 is amended by 

adding paragraph (f) to read as follows: 

§ 63.849 Test methods and procedures. 

* * * * * 

(f) The owner or operator must use 

ASTM Method D3177—02 (2007) for 

determination of the sulfur content in 

anode coke shipments to determine 


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compliance with the applicable facility 

wide emission limit for COS emissions. 

11. Section 63.850 is amended to read 

as follows: 

a. Revising paragraphs (c) and (d); 

b. Removing and reserving paragraph 

(e)(4)(iii); and 

c. Adding paragraphs (e)(4)(xvi), 

(e)(4)(xvii) and (f). 

The revisions and additions read as 

follows: 

§ 63.850 Notification, reporting and 

recordkeeping requirements. 

* * * * * 

(c) As of January 1, 2012, and within 

60 days after the date of completing 

each performance test, as defined in 

§ 63.2, and as required in this subpart, 

the owner or operator must submit 

performance test data, except opacity 

data, electronically to the EPA’s Central 

Data Exchange by using the ERT (see 

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

erttool.html/) or other compatible 

electronic spreadsheet. Only data 

collected using test methods compatible 

with ERT are subject to this requirement 

to be submitted electronically into the 

EPA’s WebFIRE database. 

(d) Reporting. In addition to the 

information required under § 63.10 of 

the General Provisions, the owner or 

operator must provide semi-annual 

reports containing the information 

specified in paragraphs (d)(1) through 

(d)(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] 

* * * * * 

(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. 

(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 

Periods of Startup. 

(a) Startup of potlines. 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 (7) of this 

section during startup for each affected 

potline. 

(1) Develop a potline startup schedule 

before starting up the potline. 

(2) Keep records of number of pots 

started per day. 

(3) Bring the potline scrubbers and 

exhaust fans on line prior to energizing 

the first cell being restarted. 

(4) Ensure that the primary capture 

and control system is operating at all 

times during startup. 

(5) Keep pots covered during startup 

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. 

(6) Inspect potlines daily during 

startup and perform the following work 

practices as specified in paragraphs 

(a)(6)(i) through (iv) 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, but no higher than the 

maximum temperature specified in the 

operating plan described in paragraph 

(a)(7) of this section; 

(iii) Reseal pot crusts that have been 

broken as often and as soon as 

practicable but in no case more than 

24 hours from the time the crust was 

broken; and 

(iv) Adjust pot parameters to their 

optimum levels, as specified in the 

operating plan described in paragraph 

(a)(7) of this section, including, but not 

limited to, the following parameters: 

Alumina addition rate, exhaust air flow, 

cell voltage, feeding level, anode current 

and liquid and solid bath levels. 

(7) Prepare a written operating plan to 

minimize emissions during startup to 

include, but not limited to, the 

requirements in (a)(1) through (6) of this 

section. 

13. Section 63.855 is added to read as 

follows: 

§ 63.855 Affirmative defense for 

exceedance of emission limit during 

malfunction. 

In response to an action to enforce the 

standards set forth in this subpart, you 

may assert an affirmative defense to a 

claim for civil penalties for exceedances 

of such standards that are caused by 

malfunction, as defined at § 63.2. 

Appropriate penalties may be assessed, 

however, if you fail to meet your burden 

of proving all of the requirements in the 

affirmative defense. The affirmative 

defense shall not be available for claims 

for injunctive relief. 

(a) To establish the affirmative 

defense in any action to enforce such a 

limit, you must timely meet the 

notification requirements in § 63.850, 

and must prove by a preponderance of 

evidence that: 

(1) The excess emissions: 

(i) Were caused by a sudden, 

infrequent, and unavoidable failure of 

air pollution control and monitoring 

equipment, process equipment, or a 

process to operate in a normal or usual 

manner; and 

(ii) Could not have been prevented 

through careful planning, proper design 

or better operation and maintenance 

practices; and 

(iii) Did not stem from any activity or 

event that could have been foreseen and 

avoided, or planned for. 

(iv) Were not part of a recurring 

pattern indicative of inadequate design, 

operation, or maintenance; and 

(2) Repairs were made as 

expeditiously as possible when the 

applicable emissions limitations were 

being exceeded. Off-shift and overtime 

labor were used, to the extent 

practicable to make these repairs; and 

(3) The frequency, amount and 

duration of the excess emissions 

(including any bypass) were minimized 

to the maximum extent practicable 

during periods of such emissions; and 

(4) If the excess emissions resulted 

from a bypass of control equipment or 

a process, then the bypass was 

unavoidable to prevent loss of life, 


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76290 Federal Register / Vol. 76, No. 234 / Tuesday, December 6, 2011 / Proposed Rules 

personal injury, or severe property 

damage; and 

(5) All possible steps were taken to 

minimize the impact of the excess 

emissions on ambient air quality, the 

environment and human health; and 

(6) All emissions monitoring and 

control systems were kept in operation 

if at all possible, consistent with safety 

and good air pollution control practices; 

and 

(7) All of the actions in response to 

the excess emissions were documented 

by properly signed, contemporaneous 

operating logs; and 

(8) At all times, the affected source 

was operated in a manner consistent 

with good practices for minimizing 

emissions; and 

(9) A written root cause analysis has 

been prepared, the purpose of which is 

to determine, correct, and eliminate the 

primary causes of the malfunction and 

the excess emissions resulting from the 

malfunction event at issue. The analysis 

shall also specify, using best monitoring 

methods and engineering judgment, the 

amount of excess emissions that were 

the result of the malfunction. 

(b) Notification. The owner or 

operator of the affected source 

experiencing an exceedance of its 

emissions limit(s) during a malfunction, 

shall notify the Administrator by 

telephone or facsimile transmission as 

soon as possible, but no later than two 

business days after the initial 

occurrence of the malfunction, if it 

wishes to avail itself of an affirmative 

defense to civil penalties for that 

malfunction. The owner or operator 

seeking to assert an affirmative defense, 

shall also submit a written report to the 

Administrator within 45 days of the 

initial occurrence of the exceedance of 

the standards in this subpart to 

demonstrate, with all necessary 

supporting documentation, that it has 

met the requirements set forth in 

paragraph (e) of this section. The owner 

or operator may seek an extension of 

this deadline for up to 30 additional 

days by submitting a written request to 

the Administrator before the expiration 

of the 45 day period. Until a request for 

an extension has been approved by the 

Administrator, the owner or operator is 

subject to the requirement to submit 

such report within 45 days of the initial 

occurrence of the exceedance. 

14. Table 1 to Subpart LL of Part 63 

is revised to read as follows: 

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

Type 

Monthly TF limit (1b/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 

VSS2 2 .6 2 .5 2 .5 2 .4 2 .4 2 .4 2 .4 

HSS 2 .5 2 .4 2 .4 2 .3 2 .3 2 .3 2 .3 

SWPB 1 .4 1 .3 1 .3 1 .2 1 .2 1 .2 1 .2 

15. Table 2 to Subpart LL of Part 63 

is revised to read as follows: 

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

Type 

POM limit (lb/ton) 

(for given number of potlines) 

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

HSS 3 .5 3 .2 3 .1 3 .0 3 .0 2 .9 2 .8 

VSS2 3 .5 3 .3 3 .2 3 .1 3 .0 2 .9 2 .9 

CWPB1 0 .63 0 .56 0 .52 0 .52 0 .48 0 .48 0 .48 

CWBP2 1 .4 1 .35 1 .31 1 .31 1 .26 1 .26 1 .26 

CWBP3 1 .33 1 .28 1 .28 1 .26 1 .26 1 .26 1 .26 

SWPB 0 .63 0 .56 0 .52 0 .52 0 .48 0 .48 0 .48 

16. Appendix A to Subpart LL of Part 

63 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) * * * Applies to 

subpart LL Comment 

63.1 ............................................................................................ Yes. 

63.2 ............................................................................................ Yes. 

63.3 ............................................................................................ Yes. 

63.4 ............................................................................................ Yes. 

63.5 ............................................................................................ Yes. 

63.6(a), (b), (c) ........................................................................... Yes. 

63.6(d) ........................................................................................ No ..................... Section 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. 


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Reference Section(s) * * * Applies to 

subpart LL Comment 

63.6(e)(2) ................................................................................... No ..................... Section reserved. 

63.6(e)(3) ................................................................................... No. 

63.6(f)(1) .................................................................................... No. 

63.6(g) ........................................................................................ Yes. 

63.6(h) ........................................................................................ No ..................... No opacity limits in rule. 

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

63.6(j) ......................................................................................... Yes. 

63.7(a) through (d) ..................................................................... Yes. 

63.7(e)(1) ................................................................................... No ..................... See § 63.847(d). 

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

63.7(f), (g), (h) ........................................................................... Yes. 

63.8(a) and (b) ........................................................................... 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(f) ......................................................................................... No. 

63.9(h)(4) ................................................................................... No ..................... Section reserved. 

63.10(a) ...................................................................................... Yes. 

63.10(b)(1) ................................................................................. 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 (b)(2)(v) ....................................................... No. 

63.10(b)(2)(vi) through (b)(2)(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 (c)(14) ...................................................... Yes. 

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

63.10(d)(1) through (4) .............................................................. Yes. 

63.10(d)(5) ................................................................................. No ..................... See § 63.850(d)(2) for reporting of malfunctions. 

63.10(e) and (f) .......................................................................... Yes. 

63.11 .......................................................................................... No ..................... Flares will not be used to comply with the emission limits. 

63.12 through 63.15 .................................................................. Yes. 

[FR Doc. 2011–29881 Filed 12–5–11; 8:45 am] 

BILLING CODE 6560–50–P 


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