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6560-50-P

E.O. 12866 Ferroalloys Production 2060-AQ11 Supplemental 

Proposal 20140904

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 63

[EPA-HQ-OAR-2010-0895; FRL-XXXX-X]

RIN 2060-AQ11

National Emission Standards for Hazardous Air Pollutants: 

Ferroalloys Production

AGENCY: Environmental Protection Agency (EPA).

ACTION: Supplemental notice of proposed rulemaking. 

SUMMARY: This action supplements our proposed amendments to the 

national emission standards for hazardous air pollutants 

(NESHAP) for the Ferroalloys Production source category 

published in the Federal Register on November 23, 2011. In that 

action, the Environmental Protection Agency (EPA) proposed 

amendments based on the initial technology and residual risk 

reviews for this source category. Today’s action presents a 

revised technology review and a revised residual risk review for 

the Ferroalloys Production source category and proposes 

revisions to the standards based on those reviews. This action 

also proposes new compliance requirements to meet the revised 

standards. This action would result in significant environmental 

improvements through the reduction of fugitive manganese 
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emissions and through more stringent emission limits for several 

processes.

DATES: Comments. Comments must be received on or before [INSERT 

DATE 45 DAYS AFTER DATE OF PUBLICATION IN THE FEDERAL REGISTER].

A copy of comments on the information collection provisions 

should be submitted to the Office of Management and Budget (OMB) 

on or before [INSERT THE DATE 30 DAYS AFTER DATE OF PUBLICATION

IN THE FEDERAL REGISTER.]

Public Hearing. If anyone contacts the EPA requesting a 

public hearing by [INSERT DATE 5 DAYS AFTER DATE OF PUBLICATION 

IN THE FEDERAL REGISTER] the EPA will hold a public hearing on 

[INSERT DATE 15 DAYS AFTER DATE OF PUBLICATION IN THE FEDERAL 

REGISTER] from 1:00 p.m. [Eastern Standard Time] to 8:00 p.m.

[Eastern Standard Time] in Marietta, Ohio. If the EPA holds a 

public hearing, the EPA will keep the record of the hearing open 

for 30 days after completion of the hearing to provide an 

opportunity for submission of rebuttal and supplementary 

information. 

ADDRESSES: Comments. Submit your comments, identified by Docket 

ID No. EPA-HQ-OAR-2010-0895, by one of the following methods:

• Federal eRulemaking Portal: 

http://www.regulations.gov. Follow the online

instructions for submitting comments.
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• Email: A-and-R-Docket@epa.gov. Include “Attention 

Docket ID No. EPA-HQ-OAR-2010-0895” in the subject 

line of the message.

• Fax: (202) 566-9744. Attention Docket ID Number EPAHQ-OAR-2010-0895.

• Mail: Environmental Protection Agency, EPA Docket 

Center (EPA/DC), Mail Code 28221T, Attention Docket ID 

No. EPA-HQ-OAR-2010-0895, 1200 Pennsylvania Avenue,

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/Courier Delivery: EPA Docket Center, Room 3334, 

EPA WJC West Building, 1301 Constitution Avenue, NW, 

Washington, DC 20004, Attention Docket ID No. EPA-HQOAR-2010-0895. Such deliveries are only accepted 

during the Docket’s normal hours of operation, and

special arrangements should be made for deliveries of 

boxed information.
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Instructions. Direct your comments to Docket ID No. EPA-HQOAR-2010-0895. The EPA’s policy is that all comments received 

will be included in the public docket without change and may be 

made available online at http://www.regulations.gov, including 

any personal information provided, unless the comment includes 

information claimed to be confidential business information 

(CBI) or other information whose disclosure is restricted by 

statute. Do not submit information that you consider to be CBI 

or otherwise protected through www.regulations.gov or email. The 

http://www.regulations.gov Web site is an “anonymous access” 

system, which means the EPA will not know your identity or 

contact information unless you provide it in the body of your 

comment. If you send an email comment directly to the EPA 

without going through http://www.regulations.gov, your email

address will be automatically captured and included as part of 

the comment that is placed in the public docket and made 

available on the Internet. If you submit an electronic comment, 

the EPA recommends that you include your name and other contact 

information in the body of your comment and with any disk or CDROM you submit. If the EPA cannot read your comment due to 

technical difficulties and cannot contact you for clarification, 

the EPA may not be able to consider your comment. Electronic 

files should not include special characters or any form of 
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encryption and be free of any defects or viruses. For additional 

information about the EPA’s public docket, visit the EPA Docket 

Center homepage at: http://www.epa.gov/dockets.

Docket. The EPA has established a docket for this 

rulemaking under Docket ID Number EPA-HQ-OAR-2010-0895. All 

documents in the docket are listed in the regulations.gov index. 

Although listed in the index, some information is not publicly 

available, e.g., CBI or other information whose disclosure is 

restricted by statute. Certain other material, such as 

copyrighted material, is not placed on the Internet and will be 

publicly available only in hard copy. Publicly available docket 

materials are available either electronically in regulations.gov

or in hard copy at the EPA Docket Center, EPA WJC West Building,

Room 3334, 1301 Constitution Ave., NW, Washington, DC. The 

Public Reading Room is open from 8:30 a.m. to 4:30 p.m., Monday 

through Friday, excluding legal holidays. The telephone number 

for the Public Reading Room is (202) 566-1744, and the telephone 

number for the EPA Docket Center is (202) 566-1742.

Public Hearing. If requested, we will hold a public hearing 

on [INSERT DATE 15 DAYS AFTER DATE OF PUBLICATION IN THE FEDERAL 

REGISTER], from 1:00 p.m. [Eastern Standard Time] to 8:00 p.m.

[Eastern Standard Time] in Marietta, Ohio. There will be a 

dinner break from 5:00 p.m. [Eastern Standard Time] until 6:00 
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p.m. [Eastern Standard Time]. Please contact Ms. Virginia Hunt 

of the Sector Policies and Programs Division (E143-01), Office 

of Air Quality Planning and Standards, Environmental Protection 

Agency, Research Triangle Park, NC 27711; telephone number: 919-

541-0832; email address: hunt.virginia@epa.gov; to register to 

speak at the hearing or to inquire as to whether or not a 

hearing will be held. The last day to pre-register in advance to 

speak at the hearing will be [INSERT DATE 12 DAYS AFTER 

PUBLICATION IN THE FEDERAL REGISTER]. Additionally, requests to 

speak will be taken the day of the hearing at the hearing 

registration desk, although preferences on speaking times may 

not be able to be fulfilled. If you require the service of a 

translator or special accommodations such as audio description, 

please let us know at the time of registration. If you require 

an accommodation we ask that you pre-register for the hearing, 

as we may not be able to arrange such accommodations without 

advance notice. The hearing will provide interested parties the 

opportunity to present data, views or arguments concerning the 

proposed action. The EPA will make every effort to accommodate 

all speakers who arrive and register.

FOR FURTHER INFORMATION: For questions about this proposed 

action, contact Mr. Phil Mulrine, Sector Policies and Programs 

Division (D243-02), Office of Air Quality Planning and 
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Standards, Environmental Protection Agency, Research Triangle 

Park, NC 27711; telephone (919) 541-5289; fax number: (919) 541-

3207; and email address: mulrine.phil@epa.gov. For specific 

information regarding the risk modeling methodology, contact Ms. 

Darcie Smith, Health and Environmental Impacts Division (C539–

02), Office of Air Quality Planning and Standards, U.S. 

Environmental Protection Agency, Research Triangle Park, NC 

27711; telephone number: (919) 541–2076; fax number: (919) 541–

2076; and email address: smith.darcie@epa.gov. For information 

about the applicability of the National Emissions Standards for 

Hazardous Air Pollutants (NESHAP) to a particular entity, 

contact Cary Secrest, Office of Enforcement and Compliance 

Assurance (OECA), telephone number: (202) 564-8661 and email

address: seacrest.cary@epa.gov.

SUPPLEMENTARY INFORMATION:

Preamble Acronyms and Abbreviations

We use multiple acronyms and terms in this preamble. While 

this list may not be exhaustive, to ease the reading of this 

preamble and for reference purposes, the EPA defines the 

following terms and acronyms here: 

AEGL acute exposure guideline levels 

AERMOD air dispersion model used by the HEM-3 model

ATSDR Agency for Toxic Substances and Disease Registry

BLDS bag leak detection system

BTF Beyond the Floor
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CAA Clean Air Act

CalEPA California EPA

CBI Confidential Business Information

CFR Code of Federal Regulations

EJ environmental justice

EPA Environmental Protection Agency

ERPG Emergency Response Planning Guidelines 

ERT Electronic Reporting Tool

FR Federal Register

HAP hazardous air pollutants

HCl hydrochloric acid

HEM-3 Human Exposure Model, Version 1.1.0

HI Hazard Index

HQ Hazard Quotient

ICR Information Collection Request

IRIS Integrated Risk Information System

km kilometer

LOAEL lowest-observed-adverse-effect level

MACT maximum achievable control technology

MACT Code Code within the National Emissions Inventory used to 

identify processes included in a source category

mg/dscm milligrams per dry standard cubic meter 

mg/kg-day milligrams per kilogram-day

mg/m3 milligrams per cubic meter

MIR maximum individual risk

MRL Minimal Risk Level

NAAQS National Ambient Air Quality Standards

NAICS North American Industry Classification System

NAS National Academy of Sciences

NATA National Air Toxics Assessment

NESHAP National Emissions Standards for Hazardous Air 

Pollutants

NOAEL no-observed-adverse-effect level

NRC National Research Council

NTTAA National Technology Transfer and Advancement Act

OAQPS Office of Air Quality Planning and Standards

OECA Office of Enforcement and Compliance Assurance

OMB Office of Management and Budget
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PAH polycyclic aromatic hydrocarbons

PB-HAP hazardous air pollutants known to be persistent and 

bio-accumulative in the environment 

PEL probable effect level

PM particulate matter

POM polycyclic organic matter

ppm parts per million

RDL representative method detection level

REL reference exposure level 

RFA Regulatory Flexibility Act

RfC reference concentration

RfD reference dose

RTR residual risk and technology review

SAB Science Advisory Board

SBA Small Business Administration

SSM startup, shutdown and malfunction

TOSHI target organ-specific hazard index

TPY tons per year

TRIM.FaTE Total Risk Integrated Methodology.Fate, Transport, 

and Ecological Exposure model

TTN Technology Transfer Network

UF uncertainty factor

μg/dscm micrograms per dry standard cubic meter

μg/m3 micrograms per cubic meter

UMRA Unfunded Mandates Reform Act

UPL Upper Prediction Limit

URE unit risk estimate

VCS voluntary consensus standards

Organization of this Document. The information in this preamble 

is organized as follows:

I. General Information

A. Does this action apply to me?

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

information?

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

II. Background Information
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A. What is the statutory authority for this action?

B. What is this source category and how does the current NESHAP 

regulate its HAP emissions?

C. What is the history of the Ferroalloys Production Risk and 

Technology Review? 

D. What data collection activities were conducted to support 

this action?

III. Analytical Procedures

A. For purposes of this supplemental proposal, how did we 

estimate the post-MACT risks posed by the Ferroalloys Production 

source category?

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

this supplemental proposal?

C. How did we perform the technology review?

IV. Revised Analytical Results and Proposed Decisions for the 

Ferroalloys Production Source Category

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

and 112(d)(3)?

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

C. What are our proposed decisions regarding risk acceptability, 

ample margin of safety and adverse environmental effects based 

on our revised analyses?

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

technology review?

E. What other actions are we proposing?

F. What compliance dates are we proposing?

V. Summary of the Revised Cost, Environmental and Economic 

Impacts

A. What are the affected sources?

B. What are the air quality impacts?

C. What are the cost impacts?

D. What are the economic impacts?

E. What are the benefits?

VI. Request for Comments

VII. Submitting Data Corrections

VIII. Statutory and Executive Order Reviews

A. Executive Order 12866: Regulatory Planning and Review and 

Executive Order 13563: Improving Regulation and Regulatory 

Review

B. Paperwork Reduction Act

C. Regulatory Flexibility Act

D. Unfunded Mandates Reform Act
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E. Executive Order 13132: Federalism

F. Executive Order 13175: Consultation and Coordination with 

Indian Tribal Governments

G. Executive Order 13045: Protection of Children from 

Environmental Health Risks and Safety Risks

H. Executive Order 13211: Actions Concerning Regulations That 

Significantly Affect Energy Supply, Distribution, or Use

I. National Technology Transfer and Advancement Act

J. Executive Order 12898: Federal Actions to Address 

Environmental Justice in Minority Populations and Low-Income 

Populations

I. General Information 

A. Does this action apply to me?

Table 1 of this preamble lists the industrial source 

category that is the subject of this supplemental proposal. 

Table 1 is not intended to be exhaustive but rather to provide a 

guide for readers regarding the entities that this proposed 

action is likely to affect. The proposed standards, once 

finalized, will be directly applicable to the affected sources. 

Federal, state, local and tribal government agencies are not 

affected by this proposed action. As defined in the “Initial 

List of Categories of Sources Under Section 112(c)(1) of the 

Clean Air Act Amendments of 1990” (see 57 FR 31576, July 16, 

1992), the “Ferroalloys Production” source category is any 

facility engaged in producing ferroalloys such as ferrosilicon, 

ferromanganese and ferrochrome.1 The EPA redefined the 

 

1 U.S. EPA. Documentation for Developing the Initial Source Category List –

Final Report, EPA/OAQPS, EPA-450/3-91-030, July, 1992.
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Ferroalloys Production source category when it promulgated the 

1999 Ferroalloys Production standard so that it now includes 

only major sources that produce products containing manganese

(Mn). (64 FR 27450, May 20, 1999.) The 1999 standard applies 

specifically to two ferroalloy product types: Ferromanganese and 

silicomanganese.

Table 1. NESHAP AND INDUSTRIAL SOURCE CATEGORIES AFFECTED BY 

THIS PROPOSED ACTION

Source Category NESHAP NAICS 

codea

Ferroalloys Production Ferroalloys Production 331110

a 2012 North American Industry Classification System

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

information?

In addition to being available in the docket, an electronic 

copy of this action is available on the Internet through the 

EPA’s Technology Transfer Network (TTN) Web site, a forum for 

information and technology exchange in various areas of air 

pollution control. Following signature by the EPA Administrator, 

the EPA will post a copy of this proposed action at:

http://www.epa.gov/ttn/atw/ferropg.html. Following publication 

in the Federal Register, the EPA will post the Federal Register

version of the proposal and key technical documents at this same 

website. Information on the overall residual risk and technology 
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review program is available at the following Web site: 

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

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

Submitting CBI. Do not submit information containing CBI to 

the EPA through http://www.regulations.gov or email. Clearly 

mark the part or all of the information that you claim to be 

CBI. For CBI information on a disk or CD-ROM that you mail to 

the EPA, mark the outside of the disk or CD-ROM as CBI and then 

identify electronically within the disk or CD-ROM the specific 

information that is claimed as CBI. In addition to one complete 

version of the comments that includes information claimed as 

CBI, you must submit a copy of the comments that does not 

contain the information claimed as CBI for inclusion in the 

public docket. If you submit a CD-ROM or disk that does not 

contain CBI, mark the outside of the disk or CD-ROM clearly that 

it does not contain CBI. Information not marked as CBI will be 

included in the public docket and the EPA’s electronic public 

docket without prior notice. Information marked as CBI will not 

be disclosed except in accordance with procedures set forth in 

40 Code of Federal Regulations (CFR) part 2. Send or deliver 

information identified as CBI only to the following address: 

Roberto Morales, OAQPS Document Control Officer (C404-02), 

OAQPS, U.S. Environmental Protection Agency, Research Triangle 
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Park, North Carolina 27711, Attention Docket ID Number EPA-HQOAR-2010-0895.

II. Background Information

A. What is the statutory authority for this action? 

Section 112 of the Clean Air Act (CAA) establishes a twostage regulatory process to address emissions of hazardous air 

pollutants (HAP) from stationary sources. In the first stage, 

after the EPA has identified categories of sources emitting one 

or more of the HAP listed in CAA section 112(b), CAA section 

112(d) requires us to promulgate technology-based NESHAP for 

those sources. “Major sources” are those that emit or have the 

potential to emit 10 tons per year (tpy) or more of a single HAP 

or 25 tpy or more of any combination of HAP. For major sources, 

the technology-based NESHAP must reflect the maximum degree of 

emission reductions of HAPs achievable (after considering cost, 

energy requirements and non-air quality health and environmental 

impacts) and are commonly referred to as maximum achievable 

control technology (MACT) standards.

MACT standards must reflect the maximum degree of emissions 

reduction achievable through the application of measures, 

processes, methods, systems or techniques, including, but not 

limited to, measures that (1) reduce the volume of or eliminate 

pollutants through process changes, substitution of materials or 
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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 standards may take the form 

of design, equipment, work practice or operational standards 

where the EPA first determines either that (1) a pollutant 

cannot be emitted through a conveyance designed and constructed 

to emit or capture the pollutant, or that any requirement for, 

or use of, such a conveyance would be inconsistent with law; or 

(2) the application of measurement methodology to a particular 

class of sources is not practicable due to technological and 

economic limitations. CAA section 112(h)(1)-(2).

The MACT “floor” is the minimum control level allowed for 

MACT standards promulgated under CAA section 112(d)(3) and may 

not be based on cost considerations. For new sources, the MACT 

floor cannot be less stringent than the emissions control that 

is achieved in practice by the best-controlled similar source. 

The MACT floor for existing sources can be less stringent than 

floors for new sources, but not less stringent than the average 

emissions limitation achieved by the best-performing 12 percent 
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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, the EPA 

must also consider control options that are more stringent than 

the floor. We may establish standards more stringent than the 

floor based on considerations of the cost of achieving the 

emission reductions, any non-air quality health and 

environmental impacts and energy requirements.

The EPA is then required to review these technology-based 

standards and revise them “as necessary (taking into account 

developments in practices, processes, and control technologies)” 

no less frequently than every eight years. CAA section 

112(d)(6). In conducting this review, the EPA is not required to 

recalculate the MACT floor. Natural Resources Defense Council 

(NRDC) v. EPA, 529 F.3d 1077, 1084 (D.C. Cir. 2008). Association 

of Battery Recyclers, Inc. v. EPA, 716 F.3d 667 (D.C. Cir. 

2013).

The second stage in standard-setting focuses on reducing 

any remaining (i.e., “residual”) risk according to CAA section 

112(f). Section 112(f)(1) required that the EPA prepare a report 

to Congress discussing (among other things) methods of 

calculating the risks posed (or potentially posed) by sources 

after implementation of the MACT standards, the public health 
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significance of those risks and the EPA’s recommendations as to 

legislation regarding such remaining risk. The EPA prepared and 

submitted the Residual Risk Report to Congress, EPA–453/R–99–001

(Risk Report) in March 1999. CAA section 112(f)(2) then provides 

that if Congress does not act on any recommendation in the Risk 

Report, the EPA must analyze and address residual risk for each 

category or subcategory of sources 8 years after promulgation of 

such standards pursuant to CAA section 112(d).

Section 112(f)(2) of the CAA requires the EPA to determine 

for source categories subject to MACT standards whether the 

emission standards provide an ample margin of safety to protect 

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

preserves the EPA’s use of the two-step process for developing 

standards to address any residual risk and the agency’s 

interpretation of “ample margin of safety” developed in the 

National Emissions Standards for Hazardous Air Pollutants: 

Benzene Emissions from Maleic Anhydride Plants, 

Ethylbenzene/Styrene Plants, Benzene Storage Vessels, Benzene 

Equipment Leaks, and Coke By-Product Recovery Plants (Benzene 

NESHAP) (54 FR 38044, September 14, 1989). The EPA notified 

Congress in the Risk Report that the agency intended to use the 

Benzene NESHAP approach in making CAA section 112(f) residual 

risk determinations (EPA–453/R–99–001, p. ES–11). The EPA 
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subsequently adopted this approach in its residual risk 

determinations and in a challenge to the risk review for the 

Synthetic Organic Chemical Manufacturing source category, the 

United States Court of Appeals for the District of Columbia 

Circuit upheld as reasonable the EPA’s interpretation that 

subsection 112(f)(2) incorporates the approach established in 

the Benzene NESHAP. See NRDC v. EPA, 529 F.3d 1077, 1083 (D.C. 

Cir. 2008)(“[S]ubsection 112(f)(2)(B) expressly incorporates the 

EPA’s interpretation of the Clean Air Act from the Benzene 

standard, complete with a citation to the Federal Register.”); 

see also A Legislative History of the Clean Air Act Amendments 

of 1990, vol. 1, p. 877 (Senate debate on Conference Report).

The first step in the process of evaluating residual risk 

is the determination of acceptable risk. If risks are 

unacceptable, the EPA cannot consider cost in identifying the 

emissions standards necessary to bring risks to an acceptable 

level. The second step is the determination of whether standards 

must be further revised in order to provide an ample margin of 

safety to protect public health. The ample margin of safety is 

the level at which the standards must be set, unless an even 

more stringent standard is necessary to prevent, taking into 

consideration costs, energy, safety and other relevant factors, 

an adverse environmental effect.
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1. Step 1-Determination of Acceptability

The agency in the Benzene NESHAP concluded that “the 

acceptability of risk under section 112 is best judged on the 

basis of a broad set of health risk measures and information” 

and that the “judgment on acceptability cannot be reduced to any 

single factor.” Benzene NESHAP at 38046. The determination of 

what represents an “acceptable” risk is based on a judgment of 

“what risks are acceptable in the world in which we live” (Risk 

Report at 178, quoting NRDC v. EPA, 824 F. 2d 1146, 1165 (D.C. 

Cir. 1987) (en banc) (“Vinyl Chloride”), recognizing that our 

world is not risk-free.

In the Benzene NESHAP, we stated that “EPA will generally 

presume that if the risk to [the maximum exposed] individual is 

no higher than approximately one in 10 thousand, that risk level 

is considered acceptable.” 54 FR at 38045, September 14, 1989. 

We discussed the maximum individual lifetime cancer risk (or 

maximum individual risk (MIR)) as being “the estimated risk that 

a person living near a plant would have if he or she were 

exposed to the maximum pollutant concentrations for 70 years.” 

Id. We explained that this measure of risk “is an estimate of 

the upper bound of risk based on conservative assumptions, such 

as continuous exposure for 24 hours per day for 70 years.” Id.

We acknowledged that maximum individual lifetime cancer risk 
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“does not necessarily reflect the true risk, but displays a 

conservative risk level which is an upper-bound that is unlikely 

to be exceeded.” Id.

Understanding that there are both benefits and limitations 

to using the MIR as a metric for determining acceptability, we 

acknowledged in the Benzene NESHAP that “consideration of 

maximum individual risk * * * must take into account the 

strengths and weaknesses of this measure of risk.” Id.

Consequently, the presumptive risk level of 100-in-1 million (1-

in-10 thousand) provides a benchmark for judging the 

acceptability of maximum individual lifetime cancer risk, but 

does not constitute a rigid line for making that determination. 

Further, in the Benzene NESHAP, we noted that:

“[p]articular attention will also be accorded to the weight 

of evidence presented in the risk assessment of potential 

carcinogenicity or other health effects of a pollutant. 

While the same numerical risk may be estimated for an 

exposure to a pollutant judged to be a known human 

carcinogen, and to a pollutant considered a possible human 

carcinogen based on limited animal test data, the same 

weight cannot be accorded to both estimates. In considering 

the potential public health effects of the two pollutants, 

the Agency’s judgment on acceptability, including the MIR, 

will be influenced by the greater weight of evidence for 

the known human carcinogen.” 

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

that:

“[i]n establishing a presumption for MIR, rather than a 

rigid line for acceptability, the Agency intends to weigh 

it with a series of other health measures and factors. 
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These include the overall incidence of cancer or other 

serious health effects within the exposed population, the 

numbers of persons exposed within each individual lifetime 

risk range and associated incidence within, typically, a 50 

km exposure radius around facilities, the science policy 

assumptions and estimation uncertainties associated with 

the risk measures, weight of the scientific evidence for 

human health effects, other quantified or unquantified 

health effects, effects due to co-location of facilities, 

and co-emission of pollutants.” 

Id. at 38045. In some cases, these health measures and factors 

taken together may provide a more realistic description of the 

magnitude of risk in the exposed population than that provided 

by maximum individual lifetime cancer risk alone. 

As noted earlier, in NRDC v. EPA, the court held that 

section 112(f)(2) “incorporates the EPA’s interpretation of the 

Clean Air Act from the Benzene Standard.” The court further held 

that Congress’ incorporation of the Benzene standard applies 

equally to carcinogens and non-carcinogens. 529 F.3d at 1081-82. 

Accordingly, we also consider non-cancer risk metrics in our 

determination of risk acceptability and ample margin of safety.

2. Step 2-Determination of Ample Margin of Safety

CAA section 112(f)(2) requires the EPA to determine, for

source categories subject to MACT standards, whether those 

standards provide an ample margin of safety to protect public 

health. As explained in the Benzene NESHAP, “the second step of 

the inquiry, determining an ‘ample margin of safety,’ again 

includes consideration of all of the health factors, and whether 
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to reduce the risks even further.... Beyond that information, 

additional factors relating to the appropriate level of control 

will also be considered, including costs and economic impacts of 

controls, technological feasibility, uncertainties and any other 

relevant factors. Considering all of these factors, the agency 

will establish the standard at a level that provides an ample 

margin of safety to protect the public health, as required by 

section 112.” 54 FR at 38046, September 14, 1989.

According to CAA section 112(f)(2)(A), if the MACT 

standards for HAP “classified as a known, probable, or possible 

human carcinogen do not reduce lifetime excess cancer risks to 

the individual most exposed to emissions from a source in the 

category or subcategory to less than one in one million,” the 

EPA must promulgate residual risk standards for the source 

category (or subcategory), as necessary to provide an ample 

margin of safety to protect public health. In doing so, the EPA 

may adopt standards equal to existing MACT standards if the EPA 

determines that the existing standards (i.e., the MACT 

standards) are sufficiently protective. NRDC v. EPA, 529 F.3d 

1077, 1083 (D.C. Cir. 2008) (“If EPA determines that the 

existing technology-based standards provide an ’ample margin of 

safety,’ then the Agency is free to readopt those standards 

during the residual risk rulemaking.”) The EPA must also adopt 
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more stringent standards, if necessary, to prevent an adverse 

environmental effect,2 but must consider cost, energy, safety and 

other relevant factors in doing so.

The CAA does not specifically define the terms “individual 

most exposed,” “acceptable level” and “ample margin of safety.” 

In the Benzene NESHAP, 54 FR at 38044-38045, September 14, 1989, 

we stated as an overall objective:

In protecting public health with an ample margin of safety 

under section 112, EPA strives to provide maximum feasible 

protection against risks to health from hazardous air 

pollutants by (1) protecting the greatest number of persons 

possible to an individual lifetime risk level no higher 

than approximately 1-in-1 million and (2) limiting to no 

higher than approximately 1-in-10 thousand [i.e., 100-in-1 

million] the estimated risk that a person living near a

plant would have if he or she were exposed to the maximum 

pollutant concentrations for 70 years. 

The agency further stated that “[t]he EPA also considers 

incidence (the number of persons estimated to suffer cancer or 

other serious health effects as a result of exposure to a 

pollutant) to be an important measure of the health risk to the 

exposed population. Incidence measures the extent of health 

risks to the exposed population as a whole, by providing an 

estimate of the occurrence of cancer or other serious health 

effects in the exposed population.” Id. at 38045.

 

2

“Adverse environmental effect” is defined as any significant and widespread 

adverse effect, which may be reasonably anticipated to wildlife, aquatic life 

or natural resources, including adverse impacts on populations of endangered 

or threatened species or significant degradation of environmental qualities 

over broad areas. CAA section 112(a)(7).
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In the ample margin of safety decision process, the agency 

again considers all of the health risks and other health 

information considered in the first step, including the 

incremental risk reduction associated with standards more 

stringent than the MACT standard or a more stringent standard 

that EPA has determined is necessary to ensure risk is 

acceptable. In the ample margin of safety analysis, the agency 

considers additional factors, including costs and economic 

impacts of controls, technological feasibility, uncertainties 

and any other relevant factors. Considering all of these 

factors, the agency will establish the standard at a level that 

provides an ample margin of safety to protect the public health, 

as required by CAA section 112(f). 54 FR 38046, September 14, 

1989. 

B. What is this source category and how does the current NESHAP 

regulate its HAP emissions?

Ferroalloys are alloys of iron in which one or more 

chemical elements (such as chromium, manganese and silicon) are 

added into molten metal. Ferroalloys are consumed primarily in 

iron and steel making and are used to produce steel and cast 

iron products with enhanced or special properties. The 

ferroalloys products that are the focus of the NESHAP are 

ferromanganese (FeMn) and silicomanganese (SiMn), which are 
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produced by two facilities in the United States. One facility 

(Eramet) is located in Marietta, Ohio and produces both FeMn and 

SiMn. The other plant (Felman) is located in Letart, West 

Virginia and produces only SiMn.

Ferroalloys within the scope of this source category are 

produced using submerged electric arc furnaces, which are 

furnaces in which the electrodes are submerged into the charge. 

The submerged arc process is a reduction smelting operation. The 

reactants consist of metallic ores (ferrous oxides, silicon 

oxides, manganese oxides, etc.) and a carbon-source reducing 

agent, usually in the form of coke, charcoal, high- and lowvolatility coal, or wood chips. Raw materials are crushed and 

sized and then conveyed to a mix house for weighing and 

blending. Conveyors, buckets, skip hoists or cars transport the 

processed material to hoppers above the furnace. The mix is 

gravity-fed through a feed chute either continuously or 

intermittently, as needed. At high temperatures in the reaction 

zone, the carbon source reacts with metal oxides to form carbon 

monoxide and to reduce the ores to base metal.3 The molten 

material (product and slag) is tapped from the furnace, 

sometimes subject to post-furnace refining and poured into 

 

3 EPA. AP-42, 12.4. Ferroalloy Production. 10/86.
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casting beds on the furnace room floor. Once the material 

hardens, it is transported to product crushing and sizing 

systems and packaged for transport to the customer.

The NESHAP for Ferroalloys Production: Ferromanganese and 

Silicomanganese were promulgated on May 20, 1999 (64 FR 27450) 

and codified at 40 CFR part 63, subpart XXX.4 The 1999 NESHAP 

applies to all new and existing ferroalloys production 

facilities that manufacture ferromanganese or silicomanganese 

and are major sources or are co-located at major sources of HAP 

emissions. 

The existing Ferroalloys Production NESHAP rule applies to 

process emissions from the submerged arc furnaces, the metal 

oxygen refining process and the product crushing equipment;

process fugitive emissions from the furnace; and outdoor 

fugitive dust emissions sources such as roadways, yard areas and

outdoor material storage and transfer operations. For the 

electric (submerged) arc furnace process, the NESHAP specifies 

numerical emissions limits for particulate matter (as a 

surrogate for non-mercury (or particulate) metal HAP). The 

NESHAP also includes emissions limits for particulate matter 

(again as a surrogate for particulate metal HAP) for process 

 

4 The emission limits were revised on March 22, 2001 (66 FR 16024) in response 

to a petition for reconsideration submitted to the EPA following promulgation 

of the final rule and a petition for review filed in the U.S. Court of 

Appeals for the District of Columbia Circuit.
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emissions from the metal oxygen refining process and product 

crushing and screening equipment. Table 2 is a summary of the 

applicable limits in the existing Subpart XXX.

Table 2. Emission Limits in Subpart XXX

New or 

Reconstructed 

or Existing 

Source

Affected Source Applicable PM 

Emission 

Standards

Subpart XXX 

Reference

New or 

reconstructed

Submerged arc furnace 0.23 kilograms 

per hour per 

megawatt 

(kg/hr/MW) 

(0.51 pounds 

per hour per 

megawatt 

(lb/hr/MW) or 

35 milligrams 

per dry 

standard cubic 

meter (mg/dscm) 

(0.015 grains 

per dry 

standard cubic 

foot (gr/dscf)

40 CFR 

63.1652(a)(1) 

and (a)(2)

Existing Open submerged arc 

furnace producing 

ferromanganese and 

operating at a 

furnace power input 

of 22 megawatts (MW) 

or less

9.8 kg/hr (21.7 

lb/hr) 

40 CFR 

63.1652(b)(1)

Existing Open submerged arc 

furnace producing 

ferromanganese and 

operating at a 

furnace power input 

greater than 22 MW

13.5 kg/hr 

(29.8 lb/hr) 

40 CFR 

63.1652(b)(2)

Existing Open submerged arc 

furnace producing 

silicomanganese and 

operating at a 

furnace power input 

greater than 25 MW

16.3 kg/hr 

(35.9 lb/hr) 

40 CFR 

63.1652(b)(3)
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New or 

Reconstructed 

or Existing 

Source

Affected Source Applicable PM 

Emission 

Standards

Subpart XXX 

Reference

Existing Open submerged arc 

furnace producing 

silicomanganese and 

operating at a 

furnace power input 

of 25 MW or less

12.3 kg/hr 

(27.2 lb/hr) 

40 CFR 

63.1652(b)(4)

Existing Semi-sealed submerged 

arc furnace (primary, 

tapping and vent 

stacks) producing 

ferromanganese

11.2 kg/hr 

(24.7 lb/hr) 

40 CFR 

63.1652(c)

New, 

reconstructed, 

or existing

Metal oxygen refining 

process

69 mg/dscm 

(0.03 gr/dscf)

40 CFR 

63.1652(d)

New or 

reconstructed

Individual equipment 

associated with the 

product crushing and 

screening operation

50 mg/dscm 

(0.022 gr/dscf)

40 CFR 

63.1652(e)(1)

Existing Individual equipment 

associated with the 

product crushing and 

screening operation

69 mg/dscm 

(0.03 gr/dscf)

40 CFR 

63.1652(e)(2)

The 1999 NESHAP established a building opacity limit of 20 

percent that is measured during the required furnace control 

device performance test. The rule provides an excursion limit of 

60 percent opacity for one 6-minute period during the 

performance test. The opacity observation is focused only on 

emissions exiting the shop due solely to operations of any 

affected submerged arc furnace. In addition, blowing taps, 

poling and oxygen lancing of the tap hole, burndowns associated 

with electrode measurements and maintenance activities 
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associated with submerged arc furnaces and casting operations 

are exempt from the opacity standards specified in §63.1653.

For outdoor fugitive dust sources, as defined in §63.1652, 

the 1999 NESHAP requires that plants prepare and operate 

according to an outdoor fugitive dust control plan that 

describes in detail the measures that will be put in place to 

control outdoor fugitive dust emissions from the individual 

outdoor fugitive dust sources at the facility. The owner or 

operator must submit a copy of the outdoor fugitive dust control 

plan to the designated permitting authority on or before the 

applicable compliance date. 

C. What is the history of the Ferroalloys Production Risk and 

Technology Review?

Pursuant to section 112(f)(2) of the CAA, we first 

evaluated the residual risk associated with the Ferroalloys 

Production NESHAP in 2011. We also conducted a technology 

review, as required by section 112(d)(6) of the CAA. Finally, we 

also reviewed the 1999 MACT rule to determine if other 

amendments were appropriate. Based on the results of that 

previous residual risk and technology review (RTR) and the MACT 

rule review, we proposed amendments to subpart XXX on November 

23, 2011 (76 FR 72508) (referred to from here on as the 2011

proposal in the remainder of this FR notice). The proposed 
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amendments in the 2011 proposal which we are revisiting in 

today’s supplemental proposal include the following:

 revisions to particulate matter (PM) standards for 

electric arc furnaces and local ventilation control 

devices;

 emission limits for mercury, polycyclic aromatic 

hydrocarbons (PAHs), and hydrochloric acid (HCl);

 proposed requirements to control process fugitive 

emissions based on full-building enclosure with negative 

pressure, or fenceline monitoring as an alternative;

 a provision for emissions averaging; 

 amendments to the monitoring, notification, recordkeeping 

and testing requirements; and

 proposed provisions establishing an affirmative defense 

to civil penalties for violations caused by malfunctions.

The comment period for the 2011 proposal opened on November 

23, 2011, and ended on January 31, 2012. We received significant 

comments from industry representatives, environmental 

organizations local community groups. We also met with 

stakeholders (from industry, community groups and environmental 

organizations) after proposal to further discuss their comments, 

concerns and related issues. After reviewing the comments and

after consideration of additional data and information received 
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since the 2011 proposal, we determined it is appropriate to 

revise some of our analyses and publish a supplemental proposal. 

Therefore, in today’s Notice of Supplemental Proposed Rulemaking 

we present revised analyses, and based on those analyses we are 

proposing revised amendments for the items listed above to allow 

the public an opportunity to review and comment on these revised 

analyses and revised proposed amendments. In addition, we have 

reevaluated the proposed affirmative defense provisions in light 

of a recent court decision vacating an affirmative defense in 

one of the EPA’s Section 112(d) regulations. NRDC v. EPA, 749 

F.3d 1055 (D.C. Cir., 2014) (vacating affirmative defense 

provisions in Section 112(d) rule establishing emission 

standards for Portland cement kilns). In this supplemental 

proposal, we are withdrawing our 2011 proposal to include an 

affirmative defense provision in this regulation.

However, we also proposed other requirements in the 2011 

proposal (listed below) for which we have made no revisions to 

the analyses, we are not proposing any changes and are not 

reopening for public comment. The other requirements that we 

proposed in the 2011 proposal, for which we are not re-opening 

for comment, are the following:

 PM standards for metal oxygen refining processes and 

crushing and screening operations;
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 emissions limits for formaldehyde;

 elimination of SSM exemptions; and

 electronic reporting.

We will address the comments we received on these other proposed 

requirements during the public comment period for the 2011 

proposal at the time we take final action.

In the 2011 proposal, we also included information about 

several ATSDR health consultations and a study (Kim et al.) that 

had been conducted in the Marietta area. We note that the Kim et 

al. study was included in the 2012 ATSDR review of manganese. 

Since the 2011 proposal, additional studies on the potential 

toxicity of manganese have been published. These studies add to 

the literature regarding potential health effects from exposure 

to manganese and will be included, along with the complete body 

of scientific evidence, in future reviews of manganese toxicity.

D. What data collection activities were conducted to support

this action?

Commenters on the 2011 proposal expressed concern that the 

data set used in the risk assessment did not adequately reflect 

current operations at the plants. In response to these comments, 

we worked with the facilities to address these concerns and we 

obtained a significant amount of new data in order to establish 

a more robust dataset than the dataset we had for the 2011
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proposal. Specifically, the plants provided data collected 

during their 2011 and 2012 compliance tests and, in response to 

an Information Collection Request (ICR) from the EPA in December 

2012, they conducted more tests in the spring of 2013. This 

combined testing effort provided the following data:

 Additional stack test data for arsenic, cadmium, chromium, 

lead, manganese, mercury, nickel, HCl, formaldehyde, PAH, 

polychlorinated biphenyls (PCB) and dioxins/furans;

 Test data collected using updated, state-of-the-art test 

methods and procedures;

 Hazardous air pollutant (HAP) test data for all operational 

furnaces;

 Test data obtained during different seasonal conditions 

(i.e., spring and fall);

 Test data for both products (ferromanganese and 

silicomanganese) for both furnaces at Eramet (Felman only 

produces silicomanganese).

With the new data, we no longer have to extrapolate HAP 

emissions from a ratio of PM to HAP emissions from just one or 

two tested furnaces. We are also using test data collected using 

state-of-the-art test methods that provide better QA/QC of the 

test results. For mercury, test data were collected for the 

supplemental proposal using EPA Method 30B, which requires 
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paired samples collected for each test run, in addition to a 

spiked sample during the 3-run test. Test data for PAH were 

collected using CARB 429, which provides greater sensitivity, 

precision and identification of individual PAH compounds as 

compared to Method 0010 which was used for previous tests. We 

also received PCB and dioxin/furan test data that were collected 

using CARB 428, which uses high resolution instruments and 

provides a specific procedure for measuring PCBs in addition to 

dioxin/furans. 

The data described above, which we received prior to summer 

2014, were incorporated into our risk assessment, technology 

review and other MACT analyses presented in this Notice. 

However, we recently received additional test reports and data 

for PAH, mercury and PM emissions from one of the furnaces at 

Eramet (Furnace #12). We also received additional data on PM 

emissions for Furnaces #1 and #12 at Eramet and for the tapping 

baghouse at Eramet. We have not yet completed our technical 

review of these new data and we were not able to incorporate 

these new data (on PAHs, PM, or Hg) into our RTR or MACT 

analyses in time for the publication of today’s Notice.5,6 These 

 

5 Emission Measurement Summary Report. Furnace No. 12 Scrubber. PAHs and 

Mercury. Eramet Marietta, Inc. Marietta, OH. Prepared for: Eramet Marietta, 

Inc. Marietta, Ohio. Prepared by Environmental Quality Management, Inc. 1800 

Carillon Boulevard, Cincinnati, Ohio 45240. January 2013.

6 Emission Measurement Summary Report. Filterable Particulate Matter
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test reports (which we received on August 19, 2014) are 

available in the docket for today’s action. We have not yet 

determined the technical viability of these data or how these 

data would affect the RTR and MACT analyses. Nevertheless, we 

seek comment on these new data and how these data would impact 

our analyses and results presented in today’s Notice. Based on 

comments and information that we receive in response to this 

supplemental proposal, and after we complete our review of these 

data, we will consider these data as appropriate as we develop 

the final rule. 

Commenters also expressed concern that the estimated cost 

and operational impacts of the 2011 proposed process fugitive 

standards based on use of a total building enclosure requirement 

were significantly underestimated. In their comments both 

companies submitted substantial additional information and 

estimates regarding the elements, costs and impacts involved 

with constructing and operating a full building enclosure for 

their facilities. We also received comments saying that fullenclosure with negative pressure can lead to worker safety and 

health issues related to indoor air quality if the systems are 

not designed and operated appropriately to provide sufficient 

 

Furnaces 1 and 12. Eramet Marietta, Inc. Marietta, OH. Prepared for:

Eramet Marietta, Inc. Marietta, Ohio 45750-0299 Prepared by: Environmental 

Quality Management, Inc., Cincinnati, Ohio 45240. April 2014. 
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air exchanges and air conditioning in the work space. 

Furthermore, in their comments and in subsequent meetings and 

other communications, the companies also provided design and 

cost information for an alternative approach to substantially 

reduce fugitive emissions based on enhanced local capture and 

control of these emissions at each plant. In the summer of 2012 

and fall of 2013, both plants submitted updated enhanced capture 

plans and cost estimates to implement those plans. We also 

consulted with outside ventilation experts and control equipment 

vendors to re-evaluate the costs of process fugitive capture as 

well as costs of other control measures such as activated carbon 

injection. We also gathered a substantial amount of opacity data 

from both facilities and collected additional information 

regarding the processes, control technologies and modeling input 

parameters (such as stack release heights and fugitive emissions 

release characteristics). We reviewed and evaluated these data 

and information provided by the facilities, the ventilation 

experts and vendors, and revised our analyses accordingly. 

III. Analytical Procedures

A. For purposes of this supplemental proposal, how did we 

estimate the post-MACT risks posed by the Ferroalloys Production 

source category?

The EPA conducted a risk assessment that provides estimates 
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of the MIR posed by the HAP emissions from each source in the 

source category, the hazard index (HI) for chronic exposures to 

HAP with the potential to cause noncancer health effects and the 

hazard quotient (HQ) for acute exposures to HAP with the 

potential to cause noncancer health effects. The assessment also 

provides estimates of the distribution of cancer risks within 

the exposed populations, cancer incidence and an evaluation of 

the potential for adverse environmental effects. The risk 

assessment consisted of eight primary steps, as discussed in 

detail in the 2011 proposal. The docket for this rulemaking 

contains the following document which provides more information 

on the risk assessment inputs and models: Residual Risk 

Assessment for the Ferroalloys Production Source Category in 

Support of the September 2014 Supplemental Proposal (risk 

assessment document). The methods used to assess risks (as 

described in the eight primary steps below) are consistent with 

those peer-reviewed by a panel of the EPA’s Science Advisory 

Board (SAB) in 2009 and described in their peer review report 

issued in 20107; they are also consistent with the key 

recommendations contained in that report.

 

7 U.S. EPA SAB. Risk and Technology Review (RTR) Risk Assessment 

Methodologies: For Review by the EPA’s Science Advisory Board with Case 

Studies – MACT I Petroleum Refining Sources and Portland Cement 

Manufacturing, May 2010.
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1. How did we estimate actual emissions and identify the 

emissions release characteristics?

As explained previously, the revised data set for the 

ferroalloys production source category, derived from the two 

existing ferromanganese and silicomanganese production 

facilities, constitutes the basis for the revised risk 

assessment. We estimated the magnitude of emissions using 

emissions test data collected through ICRs along with additional 

data submitted voluntarily by the companies. We also collected 

information regarding emissions release characteristics such as 

stack heights, stack gas exit velocities, stack temperatures and

source locations. In addition to the quality assurance (QA) of 

the source data for the facilities contained in the data set, we 

also checked the coordinates of every emission source in the 

data set through visual observations using tools such as 

GoogleEarth and ArcView. Where coordinates were found to be 

incorrect, we identified and corrected them to the extent 

possible. We also performed a QA assessment of the emissions 

data and release characteristics to ensure the data were 

reliable and that there were no outliers. The emissions data and

the methods used to estimate emissions from all the various 

emissions sources are described in more detail in the technical 

document: Revised Development of the RTR Emissions Dataset for 
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the Ferroalloys Production Source Category for the 2014 

Supplemental Proposal, which is available in the docket for this 

action. 

2. How did we estimate MACT-allowable emissions?

The available emissions data in the RTR emissions dataset 

include estimates of the mass of HAP emitted during the 

specified annual time period. In some cases, these “actual” 

emission levels are lower than the emission levels required to 

comply with the MACT standards. The emissions level allowed to 

be emitted by the MACT standards is referred to as the “MACTallowable” emissions level. 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 

facilities could emit and still comply with national emission 

standards. We also explained that it is reasonable to consider 

actual emissions, where such data are available, in both steps 

of the risk analysis, in accordance with the Benzene NESHAP 

approach. (54 FR 38044, September 14, 1989.)
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For this supplemental proposal, we evaluated allowable 

stack emissions based on the level of control required by the 

1999 MACT standards. We also evaluated the level of reported 

actual emissions and available information on the level of 

control achieved by the emissions controls in use. Further 

explanation is provided in the technical document: Revised 

Development of the RTR Emissions Dataset for the Ferroalloys 

Production Source Category for the 2014 Supplemental Proposal, 

which is available in the docket. 

3. How did we conduct dispersion modeling, determine inhalation 

exposures and estimate individual and population inhalation 

risks?

Both long-term and short-term inhalation exposure 

concentrations and health risks from the source category 

addressed in this proposal were estimated using the Human 

Exposure Model (Community and Sector HEM-3 version 1.1.0). The 

HEM-3 performs three primary risk assessment activities: (1)

conducting dispersion modeling to estimate the concentrations of 

HAP in ambient air, (2) estimating long-term and short-term 

inhalation exposures to individuals residing within 50 

kilometers (km) of the modeled sources8, and (3) estimating 

 

8 This metric comes from the Benzene NESHAP. See 54 FR 38046.
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individual and population-level inhalation risks using the 

exposure estimates and quantitative dose-response information.

The air dispersion model used by the HEM-3 model (AERMOD) 

is one of the EPA’s preferred models for assessing pollutant 

concentrations from industrial facilities.9 To perform the 

dispersion modeling and to develop the preliminary risk 

estimates, HEM-3 draws on three data libraries. The first is a 

library of meteorological data, which is used for dispersion 

calculations. This library includes 1 year (2011) of hourly 

surface and upper air observations for more than 800

meteorological stations, selected to provide coverage of the 

United States and Puerto Rico. A second library of United States 

Census Bureau census block10 internal point locations and 

populations provides the basis of human exposure calculations 

(U.S. Census, 2010). In addition, for each census block, the 

census library includes the elevation and controlling hill 

height, which are also used in dispersion calculations. A third 

library of pollutant unit risk factors and other health 

benchmarks is used to estimate health risks. These risk factors 

and health benchmarks are the latest values recommended by the 

 

9 U.S. EPA. Revision to the Guideline on Air Quality Models: Adoption of a 

Preferred General Purpose (Flat and Complex Terrain) Dispersion Model and 

Other Revisions (70 FR 68218, November 9, 2005).

10

A census block is the smallest geographic area for which census statistics 

are tabulated. 
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EPA for HAP and other toxic air pollutants. These values are 

available at: http://www.epa.gov/ttn/atw/toxsource/summary.html 

and are discussed in more detail later in this section.

In developing the risk assessment for chronic exposures, we 

used the estimated annual average ambient air concentrations of 

each HAP emitted by each source for which we have emissions data 

in the source category. The air concentrations at each nearby 

census block centroid were used as a surrogate for the chronic 

inhalation exposure concentration for all the people who reside 

in that census block. We calculated the MIR for each facility as 

the cancer risk associated with a continuous lifetime (24 hours 

per day, 7 days per week, and 52 weeks per year for a 70-year 

period) exposure to the maximum concentration at the centroid of 

inhabited census blocks. Individual cancer risks were calculated 

by multiplying the estimated lifetime exposure to the ambient 

concentration of each of the HAP (in micrograms per cubic meter 

(μg/m3)) by its unit risk estimate (URE). The URE is an upper 

bound estimate of an individual’s probability of contracting 

cancer over a lifetime of exposure to a concentration of 1 

microgram of the pollutant per cubic meter of air. For residual 

risk assessments, we generally use URE values from the EPA’s 

Integrated Risk Information System (IRIS). For carcinogenic 

pollutants without EPA IRIS values, we look to other reputable 
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sources of cancer dose-response values, often using California 

EPA (CalEPA) URE values, where available. In cases where new, 

scientifically credible dose response values have been developed 

in a manner consistent with the EPA guidelines and have 

undergone a peer review process similar to that used by the EPA, 

we may use such dose-response values in place of, or in addition 

to, other values, if appropriate. 

In the case of nickel compounds, to provide a conservative 

estimate of potential cancer risks, we used the IRIS URE value 

for nickel subsulfide (which is considered the most potent 

carcinogen among all nickel compounds) in the assessment for the 

2011 proposed rule for ferroalloys production. In the 2011 

proposed rule, the determination of the percent of nickel 

subsulfide was considered a major factor for estimating the 

risks of cancer due to nickel-containing emissions. Nickel 

speciation information for some of the largest nickel-emitting 

sources (including oil combustion, coal combustion and others) 

suggested that at least 35 percent of total nickel emissions may 

be soluble compounds and that the cancer risk for the mixture of 

inhaled nickel compounds (based on nickel subsulfide and

representative of pure insoluble crystalline nickel) was derived 

to reflect the assumption that 65 percent of the total mass of 

nickel may be carcinogenic. 
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Based on consistent views of major scientific bodies (i.e., 

National Toxicology Program (NTP) in their 12th Report of the 

Carcinogens (ROC)11, International Agency for Research on Cancer 

(IARC)12 and other international agencies)13 that consider all 

nickel compounds to be carcinogenic, we currently consider all 

nickel compounds to have the potential of being carcinogenic to 

humans. The 12th Report of the Carcinogens states that the 

“combined results of epidemiological studies, mechanistic 

studies, and carcinogenic studies in rodents support the concept 

that nickel compounds generate nickel ions in target cells at 

sites critical for carcinogenesis, thus allowing consideration 

and evaluation of these compounds as a single group.” Although 

the precise nickel compound (or compounds) responsible for 

carcinogenic effects in humans is not always clear, studies 

indicate that nickel sulfate and the combinations of nickel 

sulfides and oxides encountered in the nickel refining 

industries cause cancer in humans (these studies are summarized 

 

11 National Toxicology Program (NTP), 2011. Report on carcinogens. 12th ed. 

Research Triangle Park, NC: US Department of Health and Human Services 

(DHHS), Public Health Service. Available online at 

http://ntp.niehs.nih.gov/ntp/roc/twelfth/roc12.pdf.

12 International Agency for Research on Cancer (IARC), 1990. IARC monographs 

on the evaluation of carcinogenic risks to humans. Chromium, nickel, and 

welding. Vol. 49. Lyons, France: International Agency for Research on Cancer, 

World Health Organization Vol. 49:256.

13 World Health Organization (WHO, 1991) and the European Union’s Scientific 

Committee on Health and Environmental Risks (SCHER, 2006).
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in a review by Grimsrud et al., 201014). The major scientific 

bodies mentioned above have also recognized that there are 

differences in toxicity and/or carcinogenic potential across the 

different nickel compounds. 

In the inhalation risk assessment for the 2011 proposed 

rule, to take a conservative approach, we considered all nickel 

compounds to have the same carcinogenic potential as nickel 

subsulfide and used the IRIS URE for nickel subsulfide to 

estimate risks due to all nickel emissions from the source 

category. However, given that there are two additional URE 

values15 derived for exposure to mixtures of nickel compounds, as 

a group, that are 2-3 fold lower than the IRIS URE for nickel 

subsulfide, the EPA also considers it reasonable to use a value 

that is 50 percent of the IRIS URE for nickel subsulfide for 

providing an estimate of the lower end of the plausible range of 

cancer potency values for different mixtures of nickel 

compounds. In the public comments provided in response to the 

proposal and available in the docket, one facility provided 

 

14 Grimsrud TK and Andersen A. Evidence of carcinogenicity in humans of 

water-soluble nickel salts. J Occup Med Toxicol 2010, 5:1-7. Available online 

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

15 Two UREs (other than the current IRIS values) have been derived for nickel 

compounds as a group: one developed by the California Department of Health 

Services (http://www.arb.ca.gov/toxics/id/summary/nickel_tech_b.pdf) and the 

other by the Texas Commission on Environmental Quality 

(http://www.epa.gov/ttn/atw/nata1999/99pdfs/healtheffectsinfo.pdf).
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additional data in the form of a laboratory test report that 

indicated it would be unlikely that 100 percent of the nickel 

from the furnace would be in the form of nickel subsulfide. 

Given our current knowledge of the carcinogenic potential of all 

nickel compounds, and the potential differences in carcinogenic 

potential across nickel compounds, we consider it reasonable to 

use a value that is 50 percent of the IRIS URE for nickel 

subsulfide for providing an estimate of the cancer potency 

values for different mixtures of nickel compounds in the revised 

data set for the current supplemental proposal.

The EPA estimated incremental individual lifetime cancer 

risks associated with emissions from the facilities in the 

source category as the sum of the risks for each of the 

carcinogenic HAP (including those classified as carcinogenic to 

humans, likely to be carcinogenic to humans, and suggestive 

evidence of carcinogenic potential16) emitted by the modeled 

sources. Cancer incidence and the distribution of individual 

cancer risks for the population within 50 km of the sources were 

 

16

These classifications also coincide with the terms "known carcinogen, 

probable carcinogen, and possible carcinogen," respectively, which are the 

terms advocated in the EPA's previous Guidelines for Carcinogen Risk 

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

risks of these individual compounds to obtain the cumulative cancer risks is 

an approach that was recommended by the EPA's Science Advisory Board (SAB) in 

their 2002 peer review of EPA's National Air Toxics Assessment (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.
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also estimated for the source category as part of this 

assessment by summing individual risks. A distance of 50 km is 

consistent with both the analysis supporting the 1989 Benzene 

NESHAP (54 FR 38044, September 14, 1989) and the limitations of 

Gaussian dispersion models, including AERMOD. 

To assess the risk of non-cancer health effects from 

chronic exposures, we summed the HQ for each of the HAP that 

affects a common target organ system to obtain the HI for that 

target organ system (or target organ-specific HI, TOSHI). The HQ 

is the estimated exposure divided by the chronic reference 

value, which is a value selected from one of several sources. 

First, the chronic reference level can be the EPA reference 

concentration (RfC) 

(http://www.epa.gov/riskassessment/glossary.htm), defined as “an 

estimate (with uncertainty spanning perhaps an order of 

magnitude) of a continuous inhalation exposure to the human 

population (including sensitive subgroups) that is likely to be 

without an appreciable risk of deleterious effects during a 

lifetime.” Alternatively, in cases where an RfC from the EPA’s 

IRIS database is not available or where the EPA determines that 

using a value other than the RfC is appropriate, the chronic 

reference level can be a value from the following prioritized 

sources: (1) The Agency for Toxic Substances and Disease 
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Registry Minimum Risk Level (MRL)

(http://www.atsdr.cdc.gov/mrls/index.asp), which is defined as 

“an estimate of daily human exposure to a hazardous substance 

that is likely to be without an appreciable risk of adverse noncancer health effects (other than cancer) over a specified 

duration of exposure”; (2) the CalEPA Chronic Reference Exposure 

Level (REL)

(http://www.oehha.ca.gov/air/hot_spots/pdf/HRAguidefinal.pdf), 

which is defined as “the concentration level (that is expressed 

in units of micrograms per cubic meter (μg/m3) for inhalation 

exposure and in a dose expressed in units of milligram per 

kilogram-day (mg/kg-day) for oral exposures), at or below which 

no adverse health effects are anticipated for a specified 

exposure duration”; or (3), as noted above, a scientifically 

credible dose-response value that has been developed in a manner 

consistent with the EPA guidelines and has undergone a peer 

review process similar to that used by the EPA, in place of or 

in concert with other values.

For the ferroalloys source category, we applied this policy 

in our estimate of noncancer inhalation hazards and note the 

following related to manganese. There is an existing IRIS RfC 
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for manganese (Mn) published in 199318. This value was used in 

the RTR risk assessment supporting the Ferroalloys Notice of 

Proposed Rulemaking19. However, since the 2011 proposal, ATSDR 

has published an assessment of Mn toxicity (2012) which includes 

a chronic inhalation value (i.e., an ATSDR Minimal Risk Level or 

MRL)

20. Both the 1993 IRIS RfC and the 2012 ATSDR MRL were based 

on the same study (Roels et al., 1993). In developing their 

assessment, ATSDR used updated dose-response modeling 

methodology (benchmark dose approach) and considered recent 

pharmacokinetic findings to support their MRL derivation. 

Consistent with Agency policy, which was supported by SAB,

21 the 

EPA has chosen in this instance to rely on the ATSDR MRL for Mn 

in the current ferroalloys supplemental proposal. 

The EPA also evaluated screening estimates of acute 

exposures and risks for each of the HAP at the point of highest 

potential off-site exposure for each facility. To do this, the

EPA estimated the risks when both the peak hourly emissions rate 

and worst-case dispersion conditions occur. We also assume that 

 

18 USEPA Integrated Risk Information System Review of Manganese (1993) 

available at http://www.epa.gov/iris/subst/0373.htm.

19 2011 Notice of proposed Rulemaking reference (76 FR 72508).

20 Agency for Toxic Substances & Disease Registry Toxicological Profile for 

Manganese (2012) available at 

http://www.atsdr.cdc.gov/toxprofiles/tp.asp?id=102&tid=23.

21 The SAB peer review of RTR Risk Assessment Methodologies is available at: 

http://yosemite.epa.gov/sab/sabproduct.nsf/4AB3966E263D943A8525771F00668381/$

File/EPA-SAB-10-007-unsigned.pdf.
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a person is located at the point of highest impact during that 

same time. In accordance with our mandate in section 112 of the 

Clean Air Act, we use the point of highest off-site exposure to 

assess the potential risk to the maximally exposed individual. 

The acute HQ is the estimated acute exposure divided by the 

acute dose-response value. In each case, the EPA calculated 

acute HQ values using best available, short-term dose-response 

values. These acute dose-response values, which are described 

below, include the acute REL, acute exposure guideline levels 

(AEGL) and emergency response planning guidelines (ERPG) for 1-

hour exposure durations. As discussed below, we used 

conservative assumptions for emissions rates, meteorology and 

exposure location for our acute analysis. 

As described in the CalEPA’s Air Toxics Hot Spots Program 

Risk Assessment Guidelines, Part I, The Determination of Acute 

Reference Exposure Levels for Airborne Toxicants, an acute REL 

value (http://www.oehha.ca.gov/air/pdf/acuterel.pdf) is defined 

as “the concentration level at or below which no adverse health 

effects are anticipated for a specified exposure duration.” Id.

at page 2. Acute REL values are based on the most sensitive, 

relevant, adverse health effect reported in the peer-reviewed

medical and toxicological literature. Acute REL values are 

designed to protect the most sensitive individuals in the 
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population through the inclusion of margins of safety. Because 

margins of safety are incorporated to address data gaps and 

uncertainties, exceeding the REL does not automatically indicate 

an adverse health impact.

As we state above, in assessing the potential risks 

associated with acute exposures to HAP, we do not follow a 

prioritization scheme and therefore we consider available doseresponse values from multiple authoritative sources. In the RTR 

program, EPA assesses acute risk using toxicity values derived 

from one hour exposures. Based on an in-depth examination of the 

available acute value for nickel [California EPA’s acute (1-

hour) REL], we have concluded that this value is not appropriate 

to use to support EPA’s risk and technology review rules. This 

conclusion takes into account: the effect on which the acute REL 

is based; aspects of the methodology used in its derivation; and 

how this assessment stands in comparison to the ATSDR 

toxicological assessment, which considered the broader nickel 

health effects database.

The broad nickel noncancer health effects database strongly 

suggests that the respiratory tract is the primary target of

nickel toxicity following inhalation exposure. The available 

database on acute noncancer respiratory effects is limited and 

was considered unsuitable for quantitative analysis of nickel 
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toxicity by both California EPA22 and ATSDR23. The California 

EPA’s acute (1-hour) REL is based on an alternative endpoint, 

immunotoxicity in mice, specifically depressed antibody response 

measured in an antibody plaque assay.

In addition, the current California acute (1-hour) REL for 

Ni includes the application of methods that are different from 

those described in EPA guidelines. Specifically, the (1-hour) 

REL applies uncertainty factors that depart from the defaults in 

EPA guidelines and does not apply an inhalation dosimetric 

adjustment factor. 

Further, the ATSDR’s intermediate MRL (relevant to Ni 

exposures for a time frame between 14 and 364 days), was 

established at the same concentration as the California EPA (1-

hour) REL, indicating that exposure to this concentration “is 

likely to be without appreciable risk of adverse noncancer 

effects” (MRL definition)24 for up to 364 days.

We have high confidence in the nickel ATSDR intermediate 

MRL. Our analysis of the broad toxicity database for nickel 

indicates that this value is based on the most biologicallyrelevant endpoint. That is, the intermediate MRL is based on a 

scientifically sound study of acute respiratory 

 

22 http://oehha.ca.gov/air/allrels.html.

23 http://www.atsdr.cdc.gov/substances/toxsubstance.asp?toxid=44.

24 Agency for Toxic Substances and Disease Registry (ATSDR), Toxic Substances 

Portal. Minimal Risk Levels (MRLs) http://www.atsdr.cdc.gov/mrls/index.asp
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toxicity. Furthermore, this value is supported by a robust 

subchronic nickel toxicity database and was derived following 

guidelines that are consistent with EPA guidelines.25 Finally, 

there are no AEGL-1/ERPG-1 or AEGL-2/ERPG-2 values available for 

nickel. Thus, for all the above mentioned reasons, we will not 

include Ni in our acute analysis for this source category or in 

future assessments unless and until an appropriate value becomes 

available.

AEGL values were derived in response to recommendations 

from the National Research Council (NRC). As described in 

Standing Operating Procedures (SOP) of the National Advisory 

Committee on Acute Exposure Guideline Levels for Hazardous 

Substances (http://www.epa.gov/oppt/aegl/pubs/sop.pdf),26 “the 

NRC’s previous name for acute exposure levels—community 

emergency exposure levels—was replaced by the term AEGL to 

reflect the broad application of these values to planning, 

response and prevention in the community, the workplace, 

transportation, the military and the remediation of Superfund 

sites.” Id. at 2. This document also states that AEGL values 

“represent threshold exposure limits for the general public and 

 

25 US EPA 2002. Review of the reference dose and reference concentration 

processes (EPA/630/P-02/002F 

December 2002, http://www.epa.gov/raf/publications/pdfs/rfd-final.pdf

26

National Academy of Sciences (NAS), 2001. Standing Operating Procedures for 

Developing Acute Exposure Levels for Hazardous Chemicals, page 2.
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are applicable to emergency exposures ranging from 10 minutes to 

eight hours.” Id. at 2.

The document lays out the purpose and objectives of AEGL by 

stating that “the primary purpose of the AEGL program and the 

National Advisory Committee for Acute Exposure Guideline Levels 

for Hazardous Substances is to develop guideline levels for 

once-in-a-lifetime, short-term exposures to airborne 

concentrations of acutely toxic, high-priority chemicals.” Id.

at 21. In detailing the intended application of AEGL values, the 

document states that “[i]t is anticipated that the AEGL values 

will be used for regulatory and nonregulatory purposes by U.S. 

Federal and state agencies and possibly the international 

community in conjunction with chemical emergency response, 

planning, and prevention programs. More specifically, the AEGL 

values will be used for conducting various risk assessments to 

aid in the development of emergency preparedness and prevention 

plans, as well as real-time emergency response actions, for 

accidental chemical releases at fixed facilities and from 

transport carriers.” Id. at 31.

The AEGL–1 value is then specifically defined as “the 

airborne concentration (expressed as ppm (parts per million) or 

mg/m3 (milligrams per cubic meter)) of a substance above which it 

is predicted that the general population, including susceptible 
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individuals, could experience notable discomfort, irritation, or 

certain asymptomatic nonsensory effects. However, the effects 

are not disabling and are transient and reversible upon 

cessation of exposure.” Id. at 3. The document also notes that, 

“Airborne concentrations below AEGL–1 represent exposure levels 

that can produce mild and progressively increasing but transient 

and nondisabling odor, taste, and sensory irritation or certain 

asymptomatic, nonsensory effects.” Id. Similarly, the document 

defines AEGL–2 values as “the airborne concentration (expressed 

as parts per million or milligrams per cubic meter) of a 

substance above which it is predicted that the general 

population, including susceptible individuals, could experience 

irreversible or other serious, long-lasting adverse health 

effects or an impaired ability to escape.” Id.

ERPG values are derived for use in emergency response, as 

described in the American Industrial Hygiene Association’s ERP 

Committee document entitled, ERPGS Procedures and 

Responsibilities

(http://sp4m.aiha.org/insideaiha/GuidelineDevelopment/ERPG/Docum

ents/ERP-SOPs2006.pdf), which states that, “Emergency Response 

Planning Guidelines were developed for emergency planning and 

are intended as health based guideline concentrations for single 
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exposures to chemicals.”27 Id. at 1. The ERPG–1 value is defined 

as “the maximum airborne concentration below which it is

believed that nearly all individuals could be exposed for up to 

1 hour without experiencing other than mild transient adverse 

health effects or without perceiving a clearly defined, 

objectionable odor.” Id. at 2. Similarly, the ERPG–2 value is 

defined as “the maximum airborne concentration below which it is 

believed that nearly all individuals could be exposed for up to 

one hour without experiencing or developing irreversible or 

other serious health effects or symptoms which could impair an 

individual’s ability to take protective action.” Id. at 1.

As can be seen from the definitions above, the AEGL and 

ERPG values include the similarly-defined severity levels 1 and 

2. For many chemicals, a severity level 1 value AEGL or ERPG has 

not been developed because the types of effects for these 

chemicals are not consistent with the AEGL-1/ERPG-1 definitions; 

in these instances, we compare higher severity level AEGL–2 or 

ERPG–2 values to our modeled exposure levels to screen for 

potential acute concerns. When AEGL-1/ERPG-1 values are 

available, they are used in our acute risk assessments.

 

27

ERP Committee Procedures and Responsibilities. November 1, 2006. American 

Industrial Hygiene Association.
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Acute REL values for 1-hour exposure durations are 

typically lower than their corresponding AEGL–1 and ERPG–1 

values. Even though their definitions are slightly different, 

AEGL–1 values are often the same as the corresponding ERPG–1 

values, and AEGL–2 values are often equal to ERPG–2 values. 

Maximum HQ values from our acute screening risk assessments 

typically result when basing them on the acute REL value for a 

particular pollutant. In cases where our maximum acute HQ value 

exceeds 1, we also report the HQ value based on the next highest 

acute dose-response value (usually the AEGL–1 and/or the ERPG–1 

value). 

To develop screening estimates of acute exposures in the 

absence of hourly emissions data, generally we first develop 

estimates of maximum hourly emissions rates by multiplying the 

average actual annual hourly emissions rates by a default factor 

to cover routinely variable emissions. We choose the factor to 

use partially based on process knowledge and engineering 

judgment. The factor chosen also reflects a Texas study of 

short-term emissions variability, which showed that most peak 

emission events in a heavily-industrialized four-county area 

(Harris, Galveston, Chambers and Brazoria Counties, Texas) were 

less than twice the annual average hourly emissions rate. The 

highest peak emissions event was 74 times the annual average 
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hourly emissions rate, and the 99th percentile ratio of peak 

hourly emissions rate to the annual average hourly emissions 

rate was 9.28 Considering this analysis, to account for more than 

99 percent of the peak hourly emissions, we apply a conservative 

screening multiplication factor of 10 to the average annual 

hourly emissions rate in our acute exposure screening

assessments as our default approach. However, we use a factor 

other than 10 if we have information that indicates that a 

different factor is appropriate for a particular source 

category. 

For this source category, data were available to determine 

process-specific factors. Some processes, for example the 

electric arc furnaces, operate continuously so there are no peak 

emissions. These processes received a factor of 1 in the acute 

assessment. Other processes, for example tapping and casting, 

have specific cycles, with peak emissions occurring for a part 

of that cycle (e.g., 30 minutes during a 2-hour period). For 

these processes, we used a factor of 4 in the acute assessment. 

Even with data available to develop process-specific factors, 

our acute assessment is still conservative in that it assumes 

that every process releases its peak emissions at the same hour

 

28

See http://www.tceq.state.tx.us/compliance/field_ops/eer/index.html or 

docket to access the source of these data.
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and that this is the same hour as the worst-case dispersion 

conditions. This results in a highly conservative exposure 

scenario. A further discussion of why this factor of 4 was 

chosen can be found in the memorandum, Revised Development of 

the RTR Emissions Dataset for the Ferroalloys Production Source 

Category for the 2014 Supplemental Proposal, available in the 

docket for this rulemaking.

As part of our acute risk assessment process, for cases 

where acute HQ values from the screening step were less than or 

equal to 1 (even under the conservative assumptions of the 

screening analysis), acute impacts were deemed negligible and no 

further analysis was performed. In cases where an acute HQ from 

the screening step was greater than 1, additional site-specific 

data were considered to develop a more refined estimate of the 

potential for acute impacts of concern. For this source 

category, the data refinements employed consisted of determining 

that the receptor with the maximum concentration was off of 

plant property. These refinements are discussed more fully in 

the Residual Risk Assessment for the Ferroalloys Production 

Source Category in Support of the September 2014 Supplemental 

Proposal, which is available in the docket for this source 

category. Ideally, we would prefer to have continuous 

measurements over time to see how the emissions vary by each 
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hour over an entire year. Having a frequency distribution of 

hourly emissions rates over a year would allow us to perform a 

probabilistic analysis to estimate potential threshold 

exceedances and their frequency of occurrence. Such an 

evaluation could include a more complete statistical treatment 

of the key parameters and elements adopted in this screening 

analysis. Recognizing that this level of data is rarely 

available, we instead rely on the multiplier approach. 

To better characterize the potential health risks 

associated with estimated acute exposures to HAP, and in 

response to a key recommendation from the SAB’s peer review of 

the EPA’s RTR risk assessment methodologies,29 we generally 

examine a wider range of available acute health metrics (e.g., 

RELs, AEGLs) than we do for our chronic risk assessments. This 

is in response to the SAB’s acknowledgement that there are 

generally more data gaps and inconsistencies in acute reference 

values than there are in chronic reference values. In some 

cases, when Reference Value Arrays30 for HAP have been developed, 

we consider additional acute values (i.e., occupational and 

 

29

The SAB peer review of RTR Risk Assessment Methodologies is available at: 

http://yosemite.epa.gov/sab/sabproduct.nsf/4AB3966E263D943A8525771F00668381/$

File/EPA-SAB-10-007-unsigned.pdf.

30

U.S. EPA. (2009) Chapter 2.9 Chemical Specific Reference Values for 

Formaldehyde in Graphical Arrays of Chemical-Specific Health Effect Reference 

Values for Inhalation Exposures (Final Report). U.S. Environmental Protection 

Agency, Washington, DC, EPA/600/R-09/061 and available online at 

http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=211003.
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international values) to provide a more complete risk 

characterization.

4. How did we conduct the multipathway exposure and risk 

screening?

The EPA conducted a screening analysis examining the 

potential for significant human health risks due to exposures 

via routes other than inhalation (i.e., ingestion). We first 

determined whether any sources in the source category emitted 

any hazardous air pollutants known to be persistent and 

bioaccumulative in the environment (PB-HAP). The PB-HAP 

compounds or compound classes are identified for the screening 

from the EPA’s Air Toxics Risk Assessment Library (available at 

http://www2.epa.gov/fera/risk-assessment-and-modeling-airtoxics-risk-assessment-reference-library).

For the Ferroalloys Production source category, we 

identified emissions of cadmium compounds, chlorinated 

dibenzodioxins and furans, lead compounds, mercury compounds and

polycyclic organic matter. Because one or more of these PB-HAP 

are emitted by at least one facility in the Ferroalloys 

Production source category, we proceeded to the second step of 

the evaluation. In this step, we determined whether the 

facility-specific emissions rates of each of the emitted PB–HAP 

were large enough to create the potential for significant non-
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inhalation human health risks under reasonable worst-case 

conditions. To facilitate this step, we developed emissions rate 

screening levels for several PB–HAP using a hypothetical upperend screening exposure scenario developed for use in conjunction 

with the EPA’s Total Risk Integrated Methodology.Fate, 

Transport, and Ecological Exposure (TRIM.FaTE) model. The PB-HAP 

with emissions rate screening level values are: lead, cadmium, 

chlorinated dibenzodioxins and furans, mercury compounds, and 

polycyclic organic matter (POM). We conducted a sensitivity 

analysis on the screening scenario to ensure that its key design 

parameters would represent the upper end of the range of 

possible values, such that it would represent a conservative but 

not impossible scenario. The facility-specific emissions rates 

of these PB–HAP were compared to the emission rate screening 

levels for these PB–HAP to assess the potential for significant 

human health risks via non-inhalation pathways. We call this 

application of the TRIM.FaTE model the Tier I TRIM-screen or 

Tier I screen.

For the purpose of developing emissions rates for our Tier 

I TRIM-screen, we derived emission levels for these PB-HAP 

(other than lead compounds) at which the maximum excess lifetime 

cancer risk would be 1-in-1 million (i.e., for polychlorinated 

dibenzodioxins and furans and POM) or, for HAP that cause non-
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cancer health effects (i.e., cadmium compounds and mercury 

compounds), the maximum hazard quotient would be 1. If the 

emissions rate of any PB-HAP included in the Tier I screen

exceeds the Tier I screening emissions rate for any facility, we 

conduct a second screen, which we call the Tier II TRIM-screen 

or Tier II screen. 

In the Tier II screen, the location of each facility that 

exceeded the Tier I emission rate is used to refine the 

assumptions associated with the environmental scenario while 

maintaining the exposure scenario assumptions. We then adjust 

the risk-based Tier I screening level for each PB-HAP for each 

facility based on an understanding of how exposure 

concentrations estimated for the screening scenario change with 

meteorology and environmental assumptions. PB-HAP emissions that 

do not exceed these new Tier II screening levels are considered 

to pose no unacceptable risks. When facilities exceed the Tier

II screening levels, it does not mean that multipathway impacts 

are significant, only that we cannot rule out that possibility 

based on the results of the screen.

If the PB-HAP emissions for a facility exceed the Tier II 

screening emissions rate and data are available, we may decide 

to conduct a more refined multipathway assessment. A refined 

assessment replaces some of the assumptions made in the Tier II 
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screen, with site-specific data. The refined assessment also 

uses the TRIM.FaTE model and facility-specific emission rate 

screening levels that are created for each PB-HAP. For the 

ferroalloys production source category, we did conduct a refined 

multipathway assessment for one facility in the category. A 

detailed discussion of the approach for this assessment can be 

found in Appendix 10 (Technical Support Document: Human Health 

Multipathway Residual Risk Assessment for the Ferroalloys 

Production Source Category) of the risk assessment document.

In evaluating the potential multi-pathway risk from 

emissions of lead compounds, rather than developing a screening 

emissions rate for them, we compared maximum estimated chronic 

inhalation exposures with the level of the current National 

Ambient Air Quality Standard (NAAQS) for lead.31 Values below the 

level of the primary (health-based) lead NAAQS were considered 

to have a low potential for multi-pathway risk. 

For further information on the multipathway analysis 

approach, see the Residual Risk Assessment for the Ferroalloys 

 

31

In doing so, EPA notes that the legal standard for a primary NAAQS – that a 

standard is requisite to protect public health and provide an adequate margin 

of safety (CAA section 109(b)) – differs from the section 112(f) standard 

(requiring among other things that the standard provide an “ample margin of 

safety”). However, the lead NAAQS is a reasonable measure of determining risk 

acceptability (i.e. the first step of the Benzene NESHAP analysis) since it 

is designed to protect the most susceptible group in the human population –

children, including children living near major lead emitting sources. 73 FR 

67002/3; 73 FR 67000/3; 73 FR 67005/1. In addition, applying the level of the 

primary lead NAAQS at the risk acceptability step is conservative, since that 

primary lead NAAQS reflects an adequate margin of safety.
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Production Source Category in Support of the September 2014 

Supplemental Proposal, which is available in the docket for this 

action.

5. How did we assess risks considering the revised emissions 

control options?

In addition to assessing baseline inhalation risks and 

potential multipathway risks, we also estimated risks 

considering the emissions reductions that would be achieved by 

the control options under consideration in this supplemental 

proposal. In these cases, the expected emissions reductions were 

applied to the specific HAP and emissions points in the RTR 

emissions dataset to develop corresponding estimates of risk 

that would exist after implementation of the proposed amendments 

in today’s action. 

6. How did we conduct the environmental risk screening 

assessment? 

a. Adverse Environmental Effect

The EPA has developed a screening approach to examine the

potential for adverse environmental effects as required under 

section 112(f)(2)(A) of the CAA. Section 112(a)(7) of the CAA 

defines “adverse environmental effect” as “any significant and 

widespread adverse effect, which may reasonably be anticipated, 

to wildlife, aquatic life, or other natural resources, including 
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adverse impacts on populations of endangered or threatened 

species or significant degradation of environmental quality over 

broad areas.”

b. Environmental HAP 

The EPA focuses on seven HAP, which we refer to as 

“environmental HAP,” in its screening analysis: five persistent 

bioaccumulative HAP (PB-HAP) and two acid gases. The five PB-HAP 

are cadmium, dioxins/furans, polycyclic organic matter (POM),

mercury (both inorganic mercury and methyl mercury) and lead

compounds. The two acid gases are hydrogen chloride (HCl) and 

hydrogen fluoride (HF). The rationale for including these seven 

HAP in the environmental risk screening analysis is presented 

below. 

The HAP that persist and bioaccumulate are of particular 

environmental concern because they accumulate in the soil, 

sediment and water. The PB-HAP are taken up, through sediment, 

soil, water, and/or ingestion of other organisms, by plants or 

animals (e.g., small fish) at the bottom of the food chain. As 

larger and larger predators consume these organisms, 

concentrations of the PB-HAP in the animal tissues increase as 

does the potential for adverse effects. The five PB-HAP we 

evaluate as part of our screening analysis account for 99.8 
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percent of all PB-HAP emissions nationally from stationary 

sources (on a mass basis from the 2005 NEI).

In addition to accounting for almost all of the mass of PBHAP emitted, we note that the TRIM.FaTE model that we use to 

evaluate multipathway risk allows us to estimate concentrations 

of cadmium compounds, dioxins/furans, POM and mercury in soil, 

sediment and water. For lead compounds, we currently do not have 

the ability to calculate these concentrations using the 

TRIM.FaTE model. Therefore, to evaluate the potential for 

adverse environmental effects from lead compounds, we compare 

the estimated HEM-modeled exposures from the source category 

emissions of lead with the level of the secondary National 

Ambient Air Quality Standard (NAAQS) for lead.32 We consider 

values below the level of the secondary lead NAAQS as unlikely 

to cause adverse environmental effects.

Due to their well-documented potential to cause direct 

damage to terrestrial plants, we include two acid gases, HCl and 

HF, in the environmental screening analysis. According to the 

2005 NEI, HCl and HF account for about 99 percent (on a mass 

basis) of the total acid gas HAP emitted by stationary sources

 

32

The secondary lead NAAQS is a reasonable measure of determining whether 

there is an adverse environmental effect since it was established considering

“effects on soils, water, crops, vegetation, man-made materials, animals, 

wildlife, weather, visibility and climate, damage to and deterioration of 

property, and hazards to transportation, as well as effects on economic 

values and on personal comfort and well-being.”
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in the U.S. In addition to the potential to cause direct damage

to plants, high concentrations of HF in the air have been linked 

to fluorosis in livestock. Air concentrations of these HAP are 

already calculated as part of the human multipathway exposure 

and risk screening analysis using the HEM3-AERMOD air dispersion 

model, and we are able to use the air dispersion modeling 

results to estimate the potential for an adverse environmental 

effect.

The EPA acknowledges that other HAP beyond the seven HAP 

discussed above may have the potential to cause adverse 

environmental effects. Therefore, the EPA may include other 

relevant HAP in its environmental risk screening in the future, 

as modeling science and resources allow. The EPA invites comment 

on the extent to which other HAP emitted by the source category 

may cause adverse environmental effects. Such information should 

include references to peer-reviewed ecological effects 

benchmarks that are of sufficient quality for making regulatory 

decisions, as well as information on the presence of organisms 

located near facilities within the source category that such 

benchmarks indicate could be adversely affected.

c. Ecological assessment endpoints and benchmarks for PB-HAP

An important consideration in the development of the EPA’s 

screening methodology is the selection of ecological assessment 
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endpoints and benchmarks. Ecological assessment endpoints are 

defined by the ecological entity (e.g., aquatic communities 

including fish and plankton) and its attributes (e.g., frequency 

of mortality). Ecological assessment endpoints can be 

established for organisms, populations, communities or 

assemblages, and ecosystems.

For PB-HAP (other than lead compounds), we evaluated the 

following community-level ecological assessment endpoints to 

screen for organisms directly exposed to HAP in soils, sediment 

and water:

 Local terrestrial communities (i.e., soil invertebrates, 

plants) and populations of small birds and mammals that 

consume soil invertebrates exposed to PB-HAP in the surface 

soil.

 Local benthic (i.e., bottom sediment dwelling insects, 

amphipods, isopods and crayfish) communities exposed to PBHAP in sediment in nearby water bodies.

 Local aquatic (water-column) communities (including fish 

and plankton) exposed to PB-HAP in nearby surface waters.

For PB-HAP (other than lead compounds), we also evaluated 

the following population-level ecological assessment endpoint to 

screen for indirect HAP exposures of top consumers via the 

bioaccumulation of HAP in food chains.
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 Piscivorous (i.e., fish-eating) wildlife consuming PB-HAPcontaminated fish from nearby water bodies.

For cadmium compounds, dioxins/furans, POM and mercury, we 

identified the available ecological benchmarks for each 

assessment endpoint. An ecological benchmark represents a 

concentration of HAP (e.g., 0.77 ug of HAP per liter of water)

that has been linked to a particular environmental effect level 

(e.g., a no-observed-adverse-effect level (NOAEL)) through 

scientific study. For PB-HAP we identified, where possible, 

ecological benchmarks at the following effect levels:

Probable effect levels (PEL): Level above which adverse 

effects are expected to occur frequently. 

Lowest-observed-adverse-effect level (LOAEL): The lowest 

exposure level tested at which there are biologically 

significant increases in frequency or severity of adverse 

effects.

No-observed-adverse-effect levels (NOAEL): The highest 

exposure level tested at which there are no biologically 

significant increases in the frequency or severity of 

adverse effect. 

We established a hierarchy of preferred benchmark sources 

to allow selection of benchmarks for each environmental HAP at 

each ecological assessment endpoint. In general, the EPA sources 
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that are used at a programmatic level (e.g., Office of Water, 

Superfund Program) were used, if available. If not, the EPA 

benchmarks used in regional programs (e.g., Superfund) were 

used. If benchmarks were not available at a programmatic or 

regional level, we used benchmarks developed by other federal 

agencies (e.g., National Oceanic and Atmospheric Administration 

(NOAA)) or state agencies. 

Benchmarks for all effect levels are not available for all 

PB-HAP and assessment endpoints. In cases where multiple effect 

levels were available for a particular PB-HAP and assessment 

endpoint, we use all of the available effect levels to help us 

to determine whether ecological risks exist and, if so, whether 

the risks could be considered significant and widespread. 

d. Ecological assessment endpoints and benchmarks for acid gases

The environmental screening analysis also evaluated 

potential damage and reduced productivity of plants due to 

direct exposure to acid gases in the air. For acid gases, we 

evaluated the following ecological assessment endpoint:

 Local terrestrial plant communities with foliage exposed to 

acidic gaseous HAP in the air.

The selection of ecological benchmarks for the effects of 

acid gases on plants followed the same approach as for PB-HAP 

(i.e., we examine all of the available benchmarks). For HCl, the 
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EPA identified chronic benchmark concentrations. We note that 

the benchmark for chronic HCl exposure to plants is greater than 

the reference concentration for chronic inhalation exposure for 

human health. This means that where the EPA includes regulatory 

requirements to prevent an exceedance of the reference 

concentration for human health, additional analyses for adverse 

environmental effects of HCl would not be necessary.

For HF, the EPA identified chronic benchmark concentrations 

for plants and evaluated chronic exposures to plants in the 

screening analysis. High concentrations of HF in the air have 

also been linked to fluorosis in livestock. However, the HF 

concentrations at which fluorosis in livestock occur are higher 

than those at which plant damage begins. Therefore, the 

benchmarks for plants are protective of both plants and 

livestock.

e. Screening Methodology

For the environmental risk screening analysis, the EPA 

first determined whether any facilities in the ferroalloys 

production source category sources emitted any of the seven 

environmental HAP. For the ferroalloys production source 

category, we identified emissions of five of the PB HAP 

(cadmium, mercury, lead compounds, dioxins and polycyclic 

organic matter) and one acid gas (HCl).
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Because one or more of the seven environmental HAP 

evaluated are emitted by the facilities in the source category, 

we proceeded to the second step of the evaluation. 

f. PB-HAP Methodology

For cadmium, mercury, POM and dioxins/furans, the 

environmental screening analysis consists of two tiers, while 

lead compounds are analyzed differently as discussed earlier. In 

the first tier, we determined whether the maximum facilityspecific emission rates of each of the emitted environmental HAP 

were large enough to create the potential for adverse 

environmental effects under reasonable worst-case environmental 

conditions. These are the same environmental conditions used in 

the human multipathway exposure and risk screening analysis. 

To facilitate this step, TRIM.FaTE was run for each PB-HAP 

under hypothetical environmental conditions designed to provide 

conservatively high HAP concentrations. The model was set to 

maximize runoff from terrestrial parcels into the modeled lake, 

which in turn, maximized the chemical concentrations in the 

water, the sediments and the fish. The resulting media 

concentrations were then used to back-calculate a screening 

level emission rate that corresponded to the relevant exposure 

benchmark concentration value for each assessment endpoint. To 

assess emissions from a facility, the reported emission rate for 
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each PB-HAP was compared to the screening level emission rate 

for that PB-HAP for each assessment endpoint. If emissions from 

a facility do not exceed the Tier I screening level, the 

facility “passes” the screen, and therefore, is not evaluated 

further under the screening approach. If emissions from a 

facility exceed the Tier I screening level, we evaluate the 

facility further in Tier II.

In Tier II of the environmental screening analysis, the 

emission rate screening levels are adjusted to account for local 

meteorology and the actual location of lakes in the vicinity of 

facilities that did not pass the Tier I screen. The modeling 

domain for each facility in the tier II analysis consists of 

eight octants. Each octant contains 5 modeled soil 

concentrations at various distances from the facility (5 soil 

concentrations x 8 octants = total of 40 soil concentrations per 

facility) and 1 lake with modeled concentrations for water, 

sediment and fish tissue. In the tier II environmental risk 

screening analysis, the 40 soil concentration points are 

averaged to obtain an average soil concentration for each 

facility for each PB-HAP. For the water, sediment and fish 

tissue concentrations, the highest value for each facility for 

each pollutant is used. If emission concentrations from a 

facility do not exceed the Tier II screening levels, the 
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facility passes the screen and typically is not evaluated 

further. If emissions from a facility exceed the Tier II

screening level, the facility does not pass the screen and, 

therefore, may have the potential to cause adverse environmental 

effects. Such facilities are evaluated further to investigate 

factors such as the magnitude and characteristics of the area of 

exceedance.

g. Acid Gas Methodology

The environmental screening analysis evaluates the 

potential phytotoxicity and reduced productivity of plants due 

to chronic exposure to acid gases. The environmental risk 

screening methodology for acid gases is a single-tier screen 

that compares the average off-site ambient air concentration 

over the modeling domain to ecological benchmarks for each of 

the acid gases. Because air concentrations are compared directly 

to the ecological benchmarks, emission-based screening levels

are not calculated for acid gases as they are in the ecological 

risk screening methodology for PB-HAPs. 

For purposes of ecological risk screening, the EPA 

identifies a potential for adverse environmental effects to 

plant communities from exposure to acid gases when the average 

concentration of the HAP around a facility exceeds the LOAEL 

ecological benchmark. In such cases, we further investigate 
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factors such as the magnitude and characteristics of the area of 

exceedance (e.g., land use of exceedance area, size of 

exceedance area) to determine if there is an adverse 

environmental effect. For further information on the 

environmental screening analysis approach, see the Residual Risk 

Assessment for the Ferroalloys Production Source Category in 

Support of the September 2014 Supplemental Proposal, which is 

available in the docket for this action.

7. How did we conduct facility-wide assessments?

To put the source category risks in context, we typically 

examine the risks from the entire “facility,” where the facility 

includes all HAP-emitting operations within a contiguous area 

and under common control. In other words, we examine the HAP 

emissions not only from the source category of interest, but 

also emissions of HAP from all other emissions sources at the 

facility for which we have data. However, for the Ferroalloys 

Production source category, we did not identify other HAP 

emissions sources located at these facilities. Thus, we did not 

perform a separate facility wide risk assessment.

8. How did we consider uncertainties in risk assessment?

In the Benzene NESHAP, we concluded that risk estimation 

uncertainty should be considered in our decision-making under 

the ample margin of safety framework. Uncertainty and the 
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potential for bias are inherent in all risk assessments, 

including those performed for this proposal. Although 

uncertainty exists, we believe that our approach, which used 

conservative tools and assumptions, ensures that our decisions 

are health protective and environmentally protective. A brief 

discussion of the uncertainties in the RTR emissions dataset, 

dispersion modeling, inhalation exposure estimates and doseresponse relationships follows below. A more thorough discussion 

of these uncertainties is included in the Revised Development of 

the RTR Emissions Dataset for the Ferroalloys Production Source 

Category for the 2014 Supplemental Proposal (Emissions Memo) and 

the other uncertainties are described in more detail in the 

Residual Risk Assessment for the Ferroalloys Production Source 

Category in Support of the September 2014 Supplemental Proposal, 

which is available in the docket for this action.

a. Uncertainties in the RTR Emissions Dataset

Although the development of the RTR emissions dataset 

involved quality assurance/quality control processes, the 

accuracy of emissions values will vary depending on the source 

of the data, the degree to which data are incomplete or missing, 

the degree to which assumptions made to complete the datasets 

are accurate, errors in emission estimates and other factors. 

The emission estimates considered in this analysis generally are 
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annual totals for certain years, and they do not reflect shortterm fluctuations during the course of a year or variations from 

year to year. The estimates of peak hourly emission rates for 

the acute effects screening assessment were based on an emission 

adjustment factor applied to the average annual hourly emission 

rates, which are intended to account for emission fluctuations 

due to normal facility operations. 

As described above and in the emissions technical document, 

we gathered a substantial amount of emissions test data for the 

stack emissions from both facilities. Therefore, the level of 

uncertainty in the estimates of HAP emissions from the stacks is 

relatively low. Regarding fugitive emissions, we lack direct 

quantitative measurements of these emissions, therefore, we had 

to rely on available emissions factors and other technical 

information to derive the best estimates of emissions for these 

emissions. To estimate these fugitive emissions, we relied on 

information and observations gathered through several site 

visits by the EPA technical experts, reviewed and evaluated all 

available emissions factors and analyzed other relevant 

information such as the measured ratios of HAP metals to 

particulate matter, estimated capture efficiencies of the 

various ventilation hoods currently used to capture and control 

some of the fugitive emissions and the production rates for 
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various products. Based on this information, we have derived the 

best estimates of fugitive emissions from these sources. Details 

are described in the Emissions Memo, which is available in the 

docket for this action. Nevertheless, there are still some 

uncertainties regarding the precise quantities of fugitive HAP 

being emitted from these plants. 

b. Uncertainties in Dispersion Modeling

We recognize there is uncertainty in ambient concentration 

estimates associated with any model, including the EPA’s 

recommended regulatory dispersion model, AERMOD. In using a 

model to estimate ambient pollutant concentrations, the user 

chooses certain options to apply. For RTR assessments, we select 

some model options that have the potential to overestimate 

ambient air concentrations (e.g., not including plume depletion 

or pollutant transformation). We select other model options that 

have the potential to underestimate ambient impacts (e.g., not 

including building downwash). Other options that we select have 

the potential to either under- or overestimate ambient levels 

(e.g., meteorology and receptor locations). On balance, 

considering the directional nature of the uncertainties commonly 

present in ambient concentrations estimated by dispersion 

models, the approach we apply in the RTR assessments should 

yield unbiased estimates of ambient HAP concentrations.
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c. Uncertainties in Inhalation Exposure

The EPA did not include the effects of human mobility on 

exposures in the assessment. Specifically, short-term mobility 

and long-term mobility between census blocks in the modeling 

domain were not considered.

33

The approach of not considering 

short or long-term population mobility does not bias the 

estimate of the theoretical MIR (by definition), nor does it 

affect the estimate of cancer incidence because the total 

population number remains the same. It does, however, affect the 

shape of the distribution of individual risks across the 

affected population, shifting it toward higher estimated 

individual risks at the upper end and reducing the number of 

people estimated to be at lower risks, thereby increasing the 

estimated number of people at specific high risk levels (e.g., 

1-in-10 thousand or 1-in-1 million). 

In addition, the assessment predicted the chronic exposures 

at the centroid of each populated census block as surrogates for 

the exposure concentrations for all people living in that block. 

Using the census block centroid to predict chronic exposures 

tends to over-predict exposures for people in the census block 

who live farther from the facility and under-predict exposures 

 

33

Short-term mobility is movement from one micro-environment to another over 

the course of hours or days. Long-term mobility is movement from one 

residence to another over the course of a lifetime.
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for people in the census block who live closer to the facility. 

Thus, using the census block centroid to predict chronic 

exposures may lead to a potential understatement or 

overstatement of the true maximum impact, but is an unbiased 

estimate of average risk and incidence. We reduce this 

uncertainty by analyzing large census blocks near facilities 

using aerial imagery and adjusting the location of the block 

centroid to better represent the population in the block, as 

well as adding additional receptor locations where the block 

population is not well represented by a single location. 

The assessment evaluates the cancer inhalation risks 

associated with pollutant exposures over a 70-year period, which 

is the assumed lifetime of an individual. In reality, both the 

length of time that modeled emission sources at facilities 

actually operate (i.e., more or less than 70 years) and the 

domestic growth or decline of the modeled industry (i.e., the 

increase or decrease in the number or size of domestic 

facilities) will influence the future risks posed by a given 

source or source category. Depending on the characteristics of 

the industry, these factors will, in most cases, result in an 

overestimate both in individual risk levels and in the total 

estimated number of cancer cases. However, in the unlikely 

scenario where a facility maintains, or even increases, its 
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emissions levels over a period of more than 70 years, residents 

live beyond 70 years at the same location, and the residents 

spend most of their days at that location, then the cancer 

inhalation risks could potentially be underestimated. However, 

annual cancer incidence estimates from exposures to emissions 

from these sources would not be affected by the length of time 

an emissions source operates. 

The exposure estimates used in these analyses assume 

chronic exposures to ambient (outdoor) levels of pollutants. 

Because most people spend the majority of their time indoors, 

actual exposures may not be as high, depending on the 

characteristics of the pollutants modeled. For many of the HAP, 

indoor levels are roughly equivalent to ambient levels, but for 

very reactive pollutants or larger particles, indoor levels are 

typically lower. This factor has the potential to result in an 

overestimate of 25 to 30 percent of exposures.34

In addition to the uncertainties highlighted above, there 

are several factors specific to the acute exposure assessment

that the EPA conducts as part of the risk review under section 

112 of the CAA that should be highlighted. The accuracy of an 

acute inhalation exposure assessment depends on the simultaneous 

 

34

U.S. EPA. National-Scale Air Toxics Assessment for 1996. (EPA 453/R–01–003; 

January 2001; page 85.)
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occurrence of independent factors that may vary greatly, such as 

hourly emissions rates, meteorology and the presence of humans 

at the location of the maximum concentration. In the acute 

screening assessment that we conduct under the RTR program, we 

assume that peak emissions from the source category and worstcase meteorological conditions co-occur, thus resulting in 

maximum ambient concentrations. These two events are unlikely to 

occur at the same time, making these assumptions conservative. 

We then include the additional assumption that a person is

located at this point during this same time period. For this 

source category, these assumptions would tend to be worst-case 

actual exposures as it is unlikely that a person would be 

located at the point of maximum exposure during the time when 

peak emissions and worst-case meteorological conditions occur 

simultaneously.

d. Uncertainties in Dose-Response Relationships

There are uncertainties inherent in the development of the 

dose-response values used in our risk assessments for cancer 

effects from chronic exposures and non-cancer effects from both 

chronic and acute exposures. Some uncertainties may be 

considered quantitatively, and others generally are expressed in 

qualitative terms. We note as a preface to this discussion a 

point on dose-response uncertainty that is brought out in the 
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EPA’s 2005 Cancer Guidelines; namely, that “the primary goal of 

EPA actions is protection of human health; accordingly, as an 

Agency policy, risk assessment procedures, including default 

options that are used in the absence of scientific data to the 

contrary, should be health protective” (EPA 2005 Cancer 

Guidelines, pages 1–7). This is the approach followed here as 

summarized in the next several paragraphs. A complete detailed 

discussion of uncertainties and variability in dose-response 

relationships is given in the Residual Risk Assessment for the 

Ferroalloys Production Source Category in Support of the 

September 2014 Supplemental Proposal, which is available in the 

docket for this action. 

Cancer URE values used in our risk assessments are those 

that have been developed to generally provide an upper bound 

estimate of risk. That is, they represent a “plausible upper 

limit to the true value of a quantity” (although this is usually 

not a true statistical confidence limit).35 In some 

circumstances, the true risk could be as low as zero; however, 

in other circumstances the risk could be greater.36 When 

developing an upper bound estimate of risk and to provide risk 

 

35

IRIS glossary (http://www.epa.gov/NCEA/iris/help_gloss.htm).

36

An exception to this is the URE for benzene, which is considered to cover a 

range of values, each end of which is considered to be equally plausible and

which is based on maximum likelihood estimates.
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values that do not underestimate risk, health-protective default 

approaches are generally used. To err on the side of ensuring 

adequate health protection, the EPA typically uses the upper 

bound estimates rather than lower bound or central tendency 

estimates in our risk assessments, an approach that may have 

limitations for other uses (e.g., priority-setting or expected 

benefits analysis). 

Chronic non-cancer RfC and reference dose (RfD) values 

represent chronic exposure levels that are intended to be 

health-protective levels. Specifically, these values provide an 

estimate (with uncertainty spanning perhaps an order of 

magnitude) of a continuous inhalation exposure (RfC) or a daily 

oral exposure (RfD) to the human population (including sensitive 

subgroups) that is likely to be without an appreciable risk of 

deleterious effects during a lifetime. To derive values that are 

intended to be “without appreciable risk,” the methodology 

relies upon an uncertainty factor (UF) approach (U.S. EPA, 1993, 

1994) which considers uncertainty, variability and gaps in the 

available data. The UF are applied to derive reference values 

that are intended to protect against appreciable risk of 

deleterious effects. The UF are commonly default values,37 e.g., 

 

37

According to the NRC report, Science and Judgment in Risk Assessment (NRC, 

1994) “[Default] options are generic approaches, based on general scientific 
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factors of 10 or 3, used in the absence of compound-specific 

data; where data are available, UF may also be developed using 

compound-specific information. When data are limited, more 

assumptions are needed and more UF are used. Thus, there may be 

a greater tendency to overestimate risk in the sense that 

further study might support development of reference values that 

are higher (i.e., less potent) because fewer default assumptions 

are needed. However, for some pollutants, it is possible that 

risks may be underestimated.

While collectively termed “UF,” these factors account for a 

number of different quantitative considerations when using 

observed animal (usually rodent) or human toxicity data in the 

development of the RfC. The UF are intended to account for: (1) 

variation in susceptibility among the members of the human 

population (i.e., inter-individual variability); (2) uncertainty 

in extrapolating from experimental animal data to humans (i.e., 

 

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.
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interspecies differences); (3) uncertainty in extrapolating from 

data obtained in a study with less-than-lifetime exposure (i.e., 

extrapolating from sub-chronic to chronic exposure); (4) 

uncertainty in extrapolating the observed data to obtain an 

estimate of the exposure associated with no adverse effects; and 

(5) uncertainty when the database is incomplete or there are 

problems with the applicability of available studies. 

Many of the UF used to account for variability and 

uncertainty in the development of acute reference values are 

quite similar to those developed for chronic durations, but they 

more often use individual UF values that may be less than 10. 

The UF are applied based on chemical-specific or health effectspecific information (e.g., simple irritation effects do not 

vary appreciably between human individuals, hence a value of 3 

is typically used), or based on the purpose for the reference 

value (see the following paragraph). The UF applied in acute 

reference value derivation include: (1) heterogeneity among 

humans; (2) uncertainty in extrapolating from animals to humans; 

(3) uncertainty in lowest observed adverse effect (exposure) 

level to no observed adverse effect (exposure) level 

adjustments; and (4) uncertainty in accounting for an incomplete 

database on toxic effects of potential concern. Additional 

adjustments are often applied to account for uncertainty in 
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extrapolation from observations at one exposure duration (e.g., 

4 hours) to derive an acute reference value at another exposure 

duration (e.g., 1 hour). 

Not all acute reference values are developed for the same 

purpose and care must be taken when interpreting the results of 

an acute assessment of human health effects relative to the 

reference value or values being exceeded. Where relevant to the 

estimated exposures, the lack of short-term dose-response values 

at different levels of severity should be factored into the risk 

characterization as potential uncertainties.

Although every effort is made to identify appropriate human 

health effect dose-response assessment values for all pollutants 

emitted by the sources in this risk assessment, some HAP emitted 

by this source category are lacking dose-response assessments. 

Accordingly, these pollutants cannot be included in the 

quantitative risk assessment, which could result in quantitative 

estimates understating HAP risk. As we state above in section 

III.A.3, based on a recent in-depth examination of the available 

acute value for nickel (California EPA’s acute (1-hour) REL), we 

have concluded that this value is not appropriate for our 

regulatory needs in characterizing the potential for acute 

health risks. This conclusion takes into account the effect on 

which the acute REL is based, aspects of the methodology used in 
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its derivation, and how this assessment stands in comparison to 

other comprehensive toxicological assessments which considered 

the broader nickel health effects database. Also, there are no 

AEGL-1 or -2 or ERPG-1 or -2 values available to use in this 

acute risk assessment. Therefore, we will not include nickel in 

our acute analysis for this source category or in future 

assessments unless and until an appropriate value becomes 

available. 

To help to alleviate this potential underestimate, where we 

conclude similarity with a HAP for which a dose-response 

assessment value is available, we use that value as a surrogate 

for the assessment of the HAP for which no value is available. 

To the extent use of surrogates indicates appreciable risk, we 

may identify a need to increase priority for new IRIS assessment 

of that substance. We additionally note that, generally 

speaking, HAP of greatest concern due to environmental exposures 

and hazard are those for which dose-response assessments have 

been performed, reducing the likelihood of understating risk. 

Further, HAP not included in the quantitative assessment are 

assessed qualitatively and considered in the risk 

characterization that informs the risk management decisions, 

including with regard to consideration of HAP reductions 

achieved by various control options. 
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For a group of compounds that are unspeciated (e.g., glycol 

ethers), we conservatively use the most protective reference 

value of an individual compound in that group to estimate risk. 

Similarly, for an individual compound in a group (e.g., ethylene 

glycol diethyl ether) that does not have a specified reference 

value, we also apply the most protective reference value from 

the other compounds in the group to estimate risk.

e. Uncertainties in the Multipathway Assessment

For each source category, we generally rely on sitespecific levels of PB-HAP emissions to determine whether a 

refined assessment of the impacts from multipathway exposures is 

necessary. This determination is based on the results of a twotiered screening analysis that relies on the outputs from models 

that estimate environmental pollutant concentrations and human 

exposures for four PB-HAP. Two important types of uncertainty 

associated with the use of these models in RTR risk assessments 

and inherent to any assessment that relies on environmental 

modeling are model uncertainty and input uncertainty.38 

Model uncertainty concerns whether the selected models are 

appropriate for the assessment being conducted and whether they 

 

38 In the context of this discussion, the term “uncertainty” as it pertains 

to exposure and risk encompasses both variability in the range of expected 

inputs and screening results due to existing spatial, temporal, and other 

factors, as well as uncertainty in being able to accurately estimate the true 

result.
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adequately represent the actual processes that might occur for 

that situation. An example of model uncertainty is the question 

of whether the model adequately describes the movement of a 

pollutant through the soil. This type of uncertainty is 

difficult to quantify. However, based on feedback received from 

previous EPA Science Advisory Board reviews and other reviews, 

we are confident that the models used in the screen are 

appropriate and state-of-the-art for the multipathway risk 

assessments conducted in support of RTR. 

Input uncertainty is concerned with how accurately the 

models have been configured and parameterized for the assessment 

at hand. For Tier I of the multipathway screen, we configured 

the models to avoid underestimating exposure and risk. This was 

accomplished by selecting upper-end values from nationallyrepresentative data sets for the more influential parameters in 

the environmental model, including selection and spatial 

configuration of the area of interest, lake location and size, 

meteorology, surface water and soil characteristics and 

structure of the aquatic food web. We also assume an ingestion 

exposure scenario and values for human exposure factors that 

represent reasonable maximum exposures.

In Tier II of the multipathway assessment, we refine the 

model inputs to account for meteorological patterns in the 
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vicinity of the facility versus using upper-end national values 

and we identify the actual location of lakes near the facility 

rather than the default lake location that we apply in Tier I. 

By refining the screening approach in Tier II to account for 

local geographical and meteorological data, we decrease the 

likelihood that concentrations in environmental media are 

overestimated, thereby increasing the usefulness of the screen. 

The assumptions and the associated uncertainties regarding the 

selected ingestion exposure scenario are the same for Tier I and 

Tier II.

For both Tiers I and II of the multipathway assessment, our 

approach to addressing model input uncertainty is generally 

cautious. We choose model inputs from the upper end of the range 

of possible values for the influential parameters used in the 

models, and we assume that the exposed individual exhibits 

ingestion behavior that would lead to a high total exposure. 

This approach reduces the likelihood of not identifying high 

risks for adverse impacts. 

Despite the uncertainties, when individual pollutants or 

facilities do screen out, we are confident that the potential 

for adverse multipathway impacts on human health is very low. On 

the other hand, when individual pollutants or facilities do not 

screen out, it does not mean that multipathway impacts are 
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significant, only that we cannot rule out that possibility and 

that a refined multipathway analysis for the site might be 

necessary to obtain a more accurate risk characterization for 

the source category. 

For further information on uncertainties and the Tier I and 

II screening methods, refer to the risk document Appendix 4, 

Technical Support Document for TRIM-Based Multipathway Tiered 

Screening Methodology for RTR.

We also completed a refined multi-pathway assessment for 

this supplemental proposal. The refined assessment contains 

considerably less uncertainty compared to the Tier I and Tier II 

screens. Nevertheless, some uncertainties also exist with the 

refined assessments. The refined multi-pathway assessment and 

related uncertainties are described in detail in the risk 

document Appendix 10, Residual Risk Assessment for the 

Ferroalloys Production Source Category in Support of the 

September 2014 Supplemental Proposal, which is available in the 

docket for this action.

f. Uncertainties in the Environmental Risk Screening Assessment

For each source category, we generally rely on sitespecific levels of environmental HAP emissions to perform an 

environmental screening assessment. The environmental screening 

assessment is based on the outputs from models that estimate 
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environmental HAP concentrations. The same models, specifically 

the TRIM.FaTE multipathway model and the AERMOD air dispersion 

model, are used to estimate environmental HAP concentrations for 

both the human multipathway screening analysis and for the 

environmental screening analysis. Therefore, both screening 

assessments have similar modeling uncertainties.

Two important types of uncertainty associated with the use 

of these models in RTR environmental screening assessments—and 

inherent to any assessment that relies on environmental 

modeling—are model uncertainty and input uncertainty.39

Model uncertainty concerns whether the selected models are 

appropriate for the assessment being conducted and whether they 

adequately represent the movement and accumulation of 

environmental HAP emissions in the environment. For example, 

does the model adequately describe the movement of a pollutant 

through the soil? This type of uncertainty is difficult to 

quantify. However, based on feedback received from previous EPA 

Science Advisory Board reviews and other reviews, we are 

confident that the models used in the screen are appropriate and 

 

39 In the context of this discussion, the term “uncertainty,” as it pertains 

to exposure and risk assessment, encompasses both variability in the range of 

expected inputs and screening results due to existing spatial, temporal and 

other factors, as well as uncertainty in being able to accurately estimate 

the true result.
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state-of-the-art for the environmental risk assessments 

conducted in support of our RTR analyses. 

Input uncertainty is concerned with how accurately the 

models have been configured and parameterized for the assessment 

at hand. For Tier I of the environmental screen for PB-HAP, we 

configured the models to avoid underestimating exposure and risk 

to reduce the likelihood that the results indicate the risks are 

lower than they actually are. This was accomplished by selecting 

upper-end values from nationally-representative data sets for 

the more influential parameters in the environmental model, 

including selection and spatial configuration of the area of 

interest, the location and size of any bodies of water, 

meteorology, surface water and soil characteristics and 

structure of the aquatic food web. In Tier I, we used the 

maximum facility-specific emissions for the PB-HAP (other than 

lead compounds, which were evaluated by comparison to the 

secondary lead NAAQS) that were included in the environmental 

screening assessment and each of the media when comparing to 

ecological benchmarks. This is consistent with the conservative 

design of Tier I of the screen. In Tier II of the environmental 

screening analysis for PB-HAP, we refine the model inputs to 

account for meteorological patterns in the vicinity of the 

facility versus using upper-end national values, and we identify 
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the locations of water bodies near the facility location. By 

refining the screening approach in Tier II to account for local 

geographical and meteorological data, we decrease the likelihood 

that concentrations in environmental media are overestimated, 

thereby increasing the usefulness of the screen. To better 

represent widespread impacts, the modeled soil concentrations 

are averaged in Tier II to obtain one average soil concentration 

value for each facility and for each PB-HAP. For PB-HAP 

concentrations in water, sediment and fish tissue, the highest 

value for each facility for each pollutant is used.

For the environmental screening assessment for acid gases, 

we employ a single-tiered approach. We use the modeled air 

concentrations and compare those with ecological benchmarks.

For both Tiers I and II of the environmental screening 

assessment, our approach to addressing model input uncertainty 

is generally cautious. We choose model inputs from the upper end 

of the range of possible values for the influential parameters 

used in the models, and we assume that the exposed individual 

exhibits ingestion behavior that would lead to a high total 

exposure. This approach reduces the likelihood of not 

identifying potential risks for adverse environmental impacts.

Uncertainty also exists in the ecological benchmarks for 

the environmental risk screening analysis. We established a 
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hierarchy of preferred benchmark sources to allow selection of 

benchmarks for each environmental HAP at each ecological 

assessment endpoint. In general, EPA benchmarks used at a 

programmatic level (e.g., Office of Water, Superfund Program) 

were used if available. If not, we used EPA benchmarks used in 

regional programs (e.g., Superfund Program). If benchmarks were 

not available at a programmatic or regional level, we used 

benchmarks developed by other agencies (e.g., NOAA) or by state 

agencies. 

In all cases (except for lead compounds, which were

evaluated through a comparison to the NAAQS), we searched for 

benchmarks at the following three effect levels, as described in 

section III.A.6. of this notice:

1. A no-effect level (i.e., NOAEL). 

2. Threshold-effect level (i.e., LOAEL). 

3. Probable effect level (i.e., PEL). 

For some ecological assessment endpoint/environmental HAP 

combinations, we could identify benchmarks for all three effect 

levels, but for most, we could not. In one case, where different 

agencies derived significantly different numbers to represent a 

threshold for effect, we included both. In several cases, only a 

single benchmark was available. In cases where multiple effect 

levels were available for a particular PB-HAP and assessment 
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endpoint, we used all of the available effect levels to help us 

to determine whether risk exists and if the risks could be 

considered significant and widespread.

The EPA evaluates the following seven HAP in the 

environmental risk screening assessment: cadmium, 

dioxins/furans, POM, mercury (both inorganic mercury and methyl 

mercury), lead compounds, HCl and HF, where applicable. These 

seven HAP represent pollutants that can cause adverse impacts 

for plants and animals either through direct exposure to HAP in 

the air or through exposure to HAP that is deposited from the 

air onto soils and surface waters. These seven HAP also 

represent those HAP for which we can conduct a meaningful 

environmental risk screening assessment. For other HAP not 

included in our screening assessment, the model has not been 

parameterized such that it can be used for that purpose. In some 

cases, depending on the HAP, we may not have appropriate 

multipathway models that allow us to predict the concentration 

of that pollutant. The EPA acknowledges that other HAP beyond 

the seven HAP that we are evaluating may have the potential to 

cause adverse environmental effects and, therefore, the EPA may 

evaluate other relevant HAP in the future, as modeling science 

and resources allow. 
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Further information on uncertainties and the Tier I and II

screening methods is provided in Appendix 4 of the document 

“Technical Support Document for TRIM-Based Multipathway Tiered 

Screening Methodology for RTR: Summary of Approach and 

Evaluation.” Also, see the Residual Risk Assessment for the 

Ferroalloys Production Source Category in Support of the 

September 2014 Supplemental Proposal, available in the docket 

for this action.

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

this supplemental proposal?

As discussed in section II.A of this preamble, in 

evaluating and developing standards under section 112(f)(2), we 

apply a two-step process to address residual risk. In the first 

step, the EPA determines whether risks are acceptable. This 

determination “considers all health information, including risk 

estimation uncertainty, and includes a presumptive limit on 

maximum individual lifetime [cancer] risk (MIR)40 of 

approximately [1-in-10 thousand] [i.e., 100-in-1 million].” 54 

FR 38045, September 14, 1989. If risks are unacceptable, the EPA 

must determine the emissions standards necessary to bring risks 

to an acceptable level without considering costs. In the second 

 

40

Although defined as “maximum individual risk,” MIR refers only to cancer 

risk. MIR, one metric for assessing cancer risk, is the estimated risk were 

an individual exposed to the maximum level of a pollutant for a lifetime.
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step of the process, the EPA considers whether the emissions 

standards provide an ample margin of safety “in consideration of 

all health information, including the number of persons at risk 

levels higher than approximately 1-in-1 million, as well as 

other relevant factors, including costs and economic impacts, 

technological feasibility, and other factors relevant to each 

particular decision.” Id. The EPA must promulgate emission 

standards necessary to provide an ample margin of safety. 

In past residual risk actions, the EPA considered a number 

of human health risk metrics associated with emissions from the 

categories under review, including the MIR, the number of 

persons in various risk ranges, cancer incidence, the maximum 

non-cancer HI and the maximum acute non-cancer hazard. See, 

e.g., 72 FR 25138, May 3, 2007; 71 FR 42724, July 27, 2006. The 

EPA considered this health information for both actual and 

allowable emissions. See, e.g., 75 FR 65068, October 21, 2010; 

75 FR 80220, December 21, 2010; 76 FR 29032, May 19, 2011. The 

EPA also discussed risk estimation uncertainties and considered 

the uncertainties in the determination of acceptable risk and 

ample margin of safety in these past actions. The EPA considered 

this same type of information in support of this action.

The agency is considering these various measures of health 

information to inform our determinations of risk acceptability 
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and ample margin of safety under CAA section 112(f). As 

explained in the Benzene NESHAP, “the first step judgment on 

acceptability cannot be reduced to any single factor” and thus 

“[t]he Administrator believes that the acceptability of risk

under [previous] section 112 is best judged on the basis of a 

broad set of health risk measures and information.” 54 FR 38046, 

September 14, 1989. Similarly, with regard to the ample margin 

of safety determination, “the Agency again considers all of the 

health risk and other health information considered in the first 

step. Beyond that information, additional factors relating to 

the appropriate level of control will also be considered, 

including cost and economic impacts of controls, technological 

feasibility, uncertainties, and any other relevant factors.” Id.

The Benzene NESHAP approach provides flexibility regarding 

factors the EPA may consider in making determinations and how 

the EPA may weigh those factors for each source category. In 

responding to comment on our policy under the Benzene NESHAP, 

the EPA explained that:

“[t]he policy chosen by the Administrator permits 

consideration of multiple measures of health risk. Not only 

can the MIR figure be considered, but also incidence, the 

presence of non-cancer health effects, and the 

uncertainties of the risk estimates. In this way, the 

effect on the most exposed individuals can be reviewed as 

well as the impact on the general public. These factors can 

then be weighed in each individual case. This approach 

complies with the Vinyl Chloride mandate that the 

Administrator ascertain an acceptable level of risk to the 
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public by employing [her] expertise to assess available 

data. It also complies with the Congressional intent behind 

the CAA, which did not exclude the use of any particular 

measure of public health risk from the EPA's consideration 

with respect to CAA section 112 regulations, and thereby 

implicitly permits consideration of any and all measures of 

health risk which the Administrator, in [her] judgment, 

believes are appropriate to determining what will ‘protect 

the public health’.”

See 54 FR at 38057, September 14, 1989. Thus, the level of the 

MIR is only one factor to be weighed in determining 

acceptability of risks. The Benzene NESHAP explained that “an 

MIR of approximately one in 10 thousand should ordinarily be the 

upper end of the range of acceptability. As risks increase above 

this benchmark, they become presumptively less acceptable under 

CAA section 112, and would be weighed with the other health risk 

measures and information in making an overall judgment on 

acceptability. Or, the Agency may find, in a particular case, 

that a risk that includes MIR less than the presumptively 

acceptable level is unacceptable in the light of other health 

risk factors.” Id. at 38045. Similarly, with regard to the ample 

margin of safety analysis, the EPA stated in the Benzene NESHAP 

that: “EPA believes the relative weight of the many factors that 

can be considered in selecting an ample margin of safety can 

only be determined for each specific source category. This 

occurs mainly because technological and economic factors (along 

with the health-related factors) vary from source category to 
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source category.” Id. at 38061. We also consider the 

uncertainties associated with the various risk analyses, as 

discussed earlier in this preamble, in our determinations of 

acceptability and ample margin of safety.

The EPA notes that it has not considered certain health 

information to date in making residual risk determinations. At 

this time, we do not attempt to quantify those HAP risks that 

may be associated with emissions from other facilities that do 

not include the source categories in question, mobile source 

emissions, natural source emissions, persistent environmental 

pollution or atmospheric transformation in the vicinity of the 

sources in these categories. 

The agency understands the potential importance of 

considering an individual’s total exposure to HAP in addition to 

considering exposure to HAP emissions from the source category 

and facility. We recognize that such consideration may be 

particularly important when assessing non-cancer risks, where 

pollutant-specific exposure health reference levels (e.g., RfCs) 

are based on the assumption that thresholds exist for adverse 

health effects. For example, the agency recognizes that, 

although exposures attributable to emissions from a source 

category or facility alone may not indicate the potential for 

increased risk of adverse non-cancer health effects in a 
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population, the exposures resulting from emissions from the 

facility in combination with emissions from all of the other 

sources (e.g., other facilities) to which an individual is 

exposed may be sufficient to result in increased risk of adverse 

non-cancer health effects. In May 2010, the SAB advised the EPA 

“that RTR assessments will be most useful to decision makers and 

communities if results are presented in the broader context of 

aggregate and cumulative risks, including background 

concentrations and contributions from other sources in the 

area.”41

In response to the SAB recommendations, the EPA is 

incorporating cumulative risk analyses into its RTR risk 

assessments, including those reflected in this proposal. The 

agency is: (1) conducting facility-wide assessments, which 

include source category emission points as well as other 

emission points within the facilities; (2) considering sources 

in the same category whose emissions result in exposures to the 

same individuals; and (3) for some persistent and 

bioaccumulative pollutants, analyzing the ingestion route of 

exposure. In addition, the RTR risk assessments have always 

 

41

EPA’s responses to this and all other key recommendations of the SAB’s 

advisory on RTR risk assessment methodologies (which is available at: 

http://yosemite.epa.gov/sab/sabproduct.nsf/4AB3966E263D943A8525771F00668381/$

File/EPA-SAB-10-007-unsigned.pdf) are outlined in a memo to this rulemaking 

docket from David Guinnup entitled, EPA’s Actions in Response to the Key 

Recommendations of the SAB Review of RTR Risk Assessment Methodologies.
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considered aggregate cancer risk from all carcinogens and 

aggregate non-cancer hazard indices from all non-carcinogens 

affecting the same target organ system.

Although we are interested in placing source category and 

facility-wide HAP risks in the context of total HAP risks from 

all sources combined in the vicinity of each source, we are 

concerned about the uncertainties of doing so. Because of the 

contribution to total HAP risk from emission sources other than 

those that we have studied in depth during this RTR review, such 

estimates of total HAP risks would have significantly greater 

associated uncertainties than the source category or facilitywide estimates. Such aggregate or cumulative assessments would 

compound those uncertainties, making the assessments too 

unreliable.

C. How did we perform the technology review?

Our technology review focused on the identification and 

evaluation of developments in practices, processes and control 

technologies that have occurred since the MACT standards were 

promulgated. Where we identified such developments, in order to 

inform our decision of whether it is “necessary” to revise the 

emissions standards, we analyzed the technical feasibility of 

applying these developments and the estimated costs, energy 

implications, non-air environmental impacts, as well as 
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considering the emission reductions. We also considered the 

appropriateness of applying controls to new sources versus 

retrofitting existing sources.

Based on our analyses of the available data and 

information, we identified potential developments in practices, 

processes and control technologies. For this exercise, we 

considered any of the following to be a “development”:

 Any add-on control technology or other equipment that was 

not identified and considered during development of the 

original MACT standards.

 Any improvements in add-on control technology or other 

equipment (that were identified and considered during 

development of the original MACT standards) that could 

result in additional emissions reduction.

 Any work practice or operational procedure that was not 

identified or considered during development of the original 

MACT standards.

 Any process change or pollution prevention alternative that 

could be broadly applied to the industry and that was not 

identified or considered during development of the original 

MACT standards.

 Any significant changes in the cost (including cost 

effectiveness) of applying controls (including controls the 

EPA considered during the development of the original MACT 

standards).

We reviewed a variety of data sources in our investigation 

of potential practices, processes or controls to consider. Among 

the sources we reviewed were the NESHAP for various industries 

that were promulgated since the MACT standards being reviewed in 

this action. We reviewed the regulatory requirements and/or 
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technical analyses associated with these regulatory actions to 

identify any practices, processes and control technologies 

considered in these efforts that could be applied to emission 

sources in the Ferroalloys Production source category, as well 

as the costs, non-air impacts and energy implications associated 

with the use of these technologies. Additionally, we requested 

information from facilities regarding developments in practices, 

processes or control technology. Finally, we reviewed 

information from other sources, such as state and/or local 

permitting agency databases and industry-supported databases.

For the 2011 proposal, our technology review focused on the 

identification and evaluation of developments in practices, 

processes and control technologies that have occurred since the 

1999 NESHAP was promulgated. In cases where the technology 

review identified such developments, we conducted an analysis of 

the technical feasibility of applying these developments, along

with the estimated impacts (costs, emissions reductions, risk 

reductions, etc.) of applying these developments. We then made 

decisions on whether it is necessary to propose amendments to 

the 1999 NESHAP to require any of the identified developments. 

Based on our analyses of the data and information collected by 

the 2010 ICR and our general understanding of the industry and 

other available information on potential controls for this 
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industry, we identified several potential developments in 

practices, processes and control technologies. 

Based on our technology review for the 2011 proposed rule, 

we determined that there had been advances in emissions control 

measures since the Ferroalloys Production NESHAP was originally 

promulgated in 1999. Based on that review, we proposed lower PM 

emissions limits for the process vents because we determined 

that the existing add-on control devices (baghouses and wet 

venture scrubbers) were achieving better control than that 

reflected by the emissions limits in the 1999 MACT rule. 

Furthermore, based on that previous technology review, to reduce 

fugitive process emissions, in 2011 we proposed a requirement 

for sources to enclose the furnace building, prevent the 

fugitive emissions from being released to the atmosphere by 

maintaining the furnace building under negative pressure and 

collect and duct those fugitive emissions to a control device. 

We proposed that approach in 2011, because at that time, we 

believed it represented a technically-feasible cost-effective 

advance in emissions control since the Ferroalloys Production 

NESHAP was originally promulgated in 1999. Additional details 

regarding the previously-conducted technology review can be 

found in the Technology Review for Ferroalloys Production Source 

Category (Docket No. EPA-HQ-OAR-2010-0895-0044), which is 
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available in the docket and are discussed in the preamble to the 

2011 proposal (76 FR 72508). However, we received significant 

adverse public comments regarding the proposed requirement for 

full-enclosure with negative pressure. After reviewing and 

considering the comments and other information regarding the 

costs and feasibility of full-enclosure, we determined that 

full-enclosure with negative pressure may not be feasible for 

these facilities and, if feasible, would be much more costly 

than what we had estimated for the 2011 proposal. Therefore we 

evaluated other potential approaches to reduce fugitive process 

emissions based on enhanced local capture and control of the 

fugitive emissions and secondary capture and control, which are

described in more detail below. 

We also gathered additional emissions data for the process 

vents. Therefore, we have updated and revised our technology 

review for the process vent emissions and fugitive emissions 

control options. The following paragraphs describe the up-dated 

and revised technology review and additional analyses that were 

performed for today’s supplemental proposal.

1. Process Vent Emission Limits

The ferroalloy production facilities have add-on control 

devices such as venturi scrubbers or fabric filters to control 

emissions of metal HAP from the furnace operations. The furnace 
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operations include charging, smelting and tapping. Other 

operations that take place inside the furnace buildings include 

casting and ladle treatment. The vast majority of emissions from 

the charging and smelting processes are currently vented to the 

add-on control devices. However, the percent of emissions 

currently captured and controlled from tapping, ladle treatment 

and casting are considerably lower and varies across furnaces. 

The ferroalloy production facilities also use add-on control 

devices to reduce emissions from the metal oxygen refining (MOR) 

process, local ventilation sources (e.g., tapping fugitive 

control device) and the product crushing operations. 

To evaluate the effectiveness of these emission control 

technologies currently used to reduce emissions and meet the 

emission limits in the 1999 MACT rule, an ICR under section 114 

of the Clean Air Act was sent to each of the ferroalloy 

production facilities on April 28, 2010 and December 21, 2012 to 

gather source emissions test data and other information for the 

furnaces, the MOR process and the product crushing operations. 

The HAP source test data that were collected from the control 

device outlet for each furnace include: metal HAP (arsenic, 

cadmium, chromium (total and Cr+6), lead compounds, manganese, 
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mercury and nickel)42, HCl, formaldehyde, PAH, PCB and

chlorodibenzodioxins and chlorodibenzofurans (CDD/CDF). In 

addition, emissions were measured from the furnace control 

device outlet for two non-HAP air pollutants (carbon monoxide 

and particulate matter). The pollutants measured from the MOR 

and crushing and sizing operations in 2010 include particulate 

matter (PM) and metal HAP (arsenic, total chromium, lead

compounds, manganese, mercury and nickel).43 In addition, the 

facilities provided compliance test reports from 2011 and 2012

and additional emissions data they collected voluntarily, which

included test data for PM, metal HAP (arsenic, cadmium, total 

chromium, lead compounds, manganese, mercury and nickel) and 

organic HAP (PAH, PCB, CDD/CDF) from the furnace control device 

outlets.

The test data collected from the ICR responses, the 

compliance reports and other testing indicate that the PM 

emissions from the furnace process vents (also known as process 

stacks) are well below the level of emissions allowed by the 

current emission standards in subpart XXX. In the 2011 proposal, 

 

42 Total phosphorus was also measured for the ICR using EPA Method 29; however 

this method does not distinguish between white phosphorus (which is a nonHAP) and red phosphorus (which is a HAP). Due to the uncertainty of the 

percentage of red phosphorus in the total phosphorus test results, it was 

concluded that phosphorus would not be incorporated in the emissions used for 

modeling.

43 Total phosphorus was also measured using Method 29, but was not used in the 

technology review.
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we proposed lower PM limits to reflect the better performance of 

these sources. We also proposed lower limits for the MOR process 

and the crushing and screening process vents in the 2011 

proposal. We did not receive any additional test data for the

MOR process or the crushing and screening process since the 2011 

proposal and have received no other information indicating that 

changes to the limits we proposed in 2011 for these sources are

necessary, therefore we plan no changes to the proposed emission 

standards in this supplemental proposal for the MOR process and 

the crushing and screening processes. 

However, for the furnace process vents, we did receive 

additional data and based on that data combined with the data we 

already had, we evaluated whether it is appropriate to propose 

revised emissions limits for PM from the furnace process vents. 

We also re-evaluated the proposed emission limits for the local 

ventilation system based on the new test data received. Further 

discussions of the re-evaluations and the proposed revised 

limits are presented in Section IV below.

For purposes of addressing new ferroalloy production 

facilities, we considered the feasibility of more stringent 

emission limits. Specifically, we examined what emission level 

could be met using available add-on control devices and the 

emission concentrations that could be achieved by the use of the 
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control devices. The results of this analysis and the proposed 

decisions are described in Section IV below.

2. Process Fugitive Control Standards

We re-evaluated the costs and operational feasibility 

associated with the option of requiring full building enclosure 

with negative pressure at all openings. We also consulted with 

ventilation experts working with hot process fugitives like 

those found in the ferroalloys industry (e.g., electric arc 

furnace steel mini-mills and secondary lead smelters). 

Furthermore, we received detailed information from each of the 

Ferroalloys facilities that provides an alternative approach to 

achieve significant reductions of process fugitive emissions 

using enhanced local capture, including primary and secondary 

hoods, which would effectively capture most of the fugitive 

process emissions and route these emissions to a PM control 

device (e.g., baghouse or wet scrubber). The plans provided by 

the facilities are designed to achieve a high overall level of 

control. These plans are available in the docket for this action

(identified by document numbers: EPA-HQ-OAR-2010-0895-0106 and 

EPA-HQ-OAR-2010-0895-0073).

We also reviewed other options to control process fugitive 

emissions. When we consider the evolution of the EPA rules on 

process fugitives in the metallurgical industry, we observe that 
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the primary emphasis on quantifiable emission standards is based 

on controlling stack emissions with a high degree of efficiency. 

Standards related to emissions capture are generally related to 

parameter monitoring of flow rates and damper positions of 

capture equipment when the stack emission test is occurring. 

There typically has not been an independent evaluation of the 

effectiveness of process fugitive control through local 

ventilation in a quantitative, rigorous manner. 

However, there is a history of addressing fugitive 

emissions by requiring a building opacity limit, including a 20 

percent limit in the current subpart XXX (although this limit 

also contains a 60-percent short-term excursion and it excludes 

some key process fugitives events such as casting). Subpart 

FFFFF of Part 63, National Emission Standards for Hazardous Air 

Pollutants for Integrated Iron and Steel Manufacturing 

Facilities, contains various building opacity limits ranging 

from 20 percent for existing sources to 10 percent for new 

sources. Section 60.272a in the Subpart AAa — Standards of 

Performance for Steel Plants: Electric Arc Furnaces and ArgonOxygen Decarburization Vessels Constructed After August 17, 1983 

establishes a shop building opacity limit of 6 percent, due 

solely to the operations of affected electric arc furnace 

(EAF)(s) or argon-oxygen decarburization vessel (AOD vessel)(s). 
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Building opacity limits in these rules serve as an emissions 

standard for the control of process fugitive emissions. Opacity 

limits can ensure effective capture and control of these 

fugitive emissions if they are established at the appropriate 

levels and have appropriate compliance monitoring requirements 

to ensure the fugitive emissions are minimized continuously over

time. 

After reviewing and evaluating available information 

regarding approaches to reduce process fugitive emissions, we 

revised our analysis of options to control these fugitive 

emissions. The results of the revised analyses of control 

options for process fugitive emissions are summarized in Section

IV and also presented in the Cost Impacts of Control Options to 

Address Fugitive HAP Emissions for the Ferroalloys Production 

NESHAP Supplemental Proposal document and the Revised Technology 

Review for the Ferroalloys Production Source Category for the 

Supplemental Proposal document (Revised Technology Review 

document), which are available in the docket.

IV. Revised Analytical Results and Proposed Decisions for the 

Ferroalloys Production Source Category

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

and 112(d)(3)?
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As described previously, CAA section 112(d) requires the 

EPA to promulgate national technology-based emission standards 

for hazardous air pollutants (NESHAP) for listed source 

categories, including this source category. In the 2011 

proposal, we proposed emissions limits for mercury, PAHs and 

HCl, which were previously unregulated HAP, pursuant to section 

112(d)(2) and 112(d)(3). After proposal, we received a 

substantial amount of additional data for these HAP and reanalyzed the proposed limits for these HAP considering the 

additional data. 

Based on those analyses we determined it is appropriate to 

propose revised limits for these three HAP. Therefore, in 

today’s supplemental notice, we are proposing revised emissions 

limits pursuant to section 112(d)(2) and 112(d)(3) for mercury, 

PAHs and HCl. In this section, we describe how we developed the 

revised proposed standards for these HAP, including how we 

calculated MACT floor limits, how we account for variability in 

those floor calculations and how we considered beyond the floor

(BTF) options. The revised MACT analyses for these previously 

unregulated pollutants (i.e., mercury, PAH and HCl) are 

presented in the following paragraphs. For more information on 

these analyses, see the Revised MACT Floor Analysis for the 

Ferroalloys Production Source Category and the Mercury Control 
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Options and Impacts for the Ferroalloys Production Industry

documents which are available in the docket for this action.

1. How do we develop MACT Floor limits?

As discussed in the 2011 proposal (76 FR 72508), the MACT 

floor limit for existing sources is calculated based on the 

average performance of the best performing units in each 

category or subcategory, and also on a consideration of these 

units’ variability, and the MACT floor for new sources is based 

on the single best performing source, with a similar 

consideration of that source’s variability. The MACT floor for 

new sources cannot be less stringent than the emissions 

performance that is achieved in practice by the best-controlled 

similar source. To account for variability in the operation and 

emissions, the stack test data were used to calculate the 

average emissions and the 99 percent upper predictive limit 

(UPL) to derive the MACT floor limits. For more information 

regarding the general use of the UPL and why it is appropriate 

for calculating MACT floors, see the memorandum titled Use of 

the Upper Prediction Limit for Calculating MACT Floors (UPL 

Memo), which is available in the docket for this action. 

Furthermore, with regard to calculation of MACT Floor limits 

based on limited datasets, we considered additional factors as 

summarized below and described in more details in the memorandum 
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titled: Approach for Applying the Upper Prediction Limit to 

Limited Datasets, which is available in the docket for this 

action.

2. What is our approach for applying the upper prediction limit 

to limited datasets?

The UPL approach addresses variability of emissions data 

from the best performing source or sources in setting MACT 

standards. The UPL also accounts for uncertainty associated with 

emission values in a dataset, which can be influenced by 

components such as the number of samples available for 

developing MACT standards and the number of samples that will be 

collected to assess compliance with the emission limit. The UPL 

approach has been used in many environmental science 

applications.44,45,46,47,48,49 As explained in more detail in the UPL 

 

44 Gibbons, R. D. (1987), Statistical Prediction Intervals for the Evaluation 

of Ground-Water Quality. Groundwater, 25: 455–465 and Hart, Barbara F. and 

Janet Chaseling, Optimizing Landfill Ground Water Analytes—New South Wales, 

Australia, Groundwater Monitoring & Remediation, 2003, 23, 2.

45 Wan, Can; Xu, Zhao; Pinson, Pierre; Dong, Zhao Yang; Wong, Kit Po. Optimal 

Prediction Intervals of Wind Power Generation. 2014. IEEE Transactions on 

Power Systems, ISSN 0885-8950, 29(3): pp. 1166 – 1174.

46 Khosravi, Abbas; Mazloumi, Ehsan; Nahavandi, Saeid; Creighton, Doug; van 

Lint, J. W. C. Prediction Intervals to Account for Uncertainties in Travel 

Time Prediction. 2011. IEEE Transactions on Intelligent Transportation 

Systems, ISSN 1524-9050, 12(2):537 – 547.

47 Ashkan Zarnani; Petr Musilek; Jana Heckenbergerova. 2014. Clustering 

numerical weather forecasts to obtain statistical prediction intervals. 

Meteorological Applications, ISSN 1350-4827. 21(3): 605.

48 Rayer, Stefan; Smith, Stanley K; Tayman, Jeff. 2009. Empirical Prediction 

Intervals for County Population Forecasts. Population Research and Policy 

Review, 28(6): 773 – 793.

49 Nicholas A Som; Nicolas P Zegre; Lisa M Ganio; Arne E Skaugset. 2012. 

Corrected prediction intervals for change detection in paired watershed 
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Memo, the EPA uses the UPL approach to reasonably estimate the 

emissions performance of the best performing source or sources 

to establish MACT floor standards.

With regard to the derivation of MACT limits using limited 

datasets, in a recent D.C. Circuit Court of Appeals decision in 

National Association of Clean Water Agencies v. EPA (NACWA), 

which involved challenges to EPA’s MACT standards for sewage 

sludge incinerators, questions were raised regarding the 

application of the UPL to limited datasets. We have since 

addressed these questions, as explained in detail in the

memorandum titled: Approach for Applying the Upper Prediction 

Limit to Limited Datasets (i.e., Limited Dataset Memo), which is 

available in the docket for this action. We seek comments on the 

approach described in the Limited Dataset Memo and whether there 

are other approaches we should consider for such datasets. We 

also seek comments on the application of this approach for the 

derivation of MACT limits based on limited datasets in this 

supplemental proposal, which are described in the following 

sections of today’s notice and in the Limited Dataset Memo. 

3. How did we apply the approach for limited datasets to limited 

datasets in the ferroalloys source category?

For the ferroalloys source category, we have limited 

 

studies. Hydrological Sciences Journal, ISSN 0262-6667, 57(1): 134 – 143
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datasets for the following pollutants and subcategories: PAHs 

for existing and new furnaces producing ferromanganese (FeMn); 

PAHs for new furnaces producing silicon manganese (SiMn); 

mercury for new furnaces producing SiMn; mercury for existing 

and new furnaces producing FeMn; and HCl for new furnaces 

producing FeMn or SiMn. Therefore, we evaluated these specific 

datasets to determine whether it is appropriate to make any 

modifications to the approach used to calculate MACT floors for 

each of these datasets.

For each dataset, we performed the steps outlined in the 

Limited Dataset Memo, including: ensuring that we selected the 

data distribution that best represents each dataset; ensuring 

that the correct equation for the distribution was then applied 

to the data; and comparing individual components of each small 

dataset to determine if the standards based on small datasets 

reasonably represent the performance of the units included in 

the dataset. The results of each analysis are described and 

presented below in the applicable sections for each of the three 

HAP (i.e., mercury, PAHs and HCl). We seek comments regarding 

the specific application of the limited dataset approach used to 

derive the proposed emissions limits for Hg, PAHs and HCl 

described in the sections below. 

4. How did we develop proposed limits for mercury emissions?
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a. Background on mercury

As described above, we obtained significant additional data 

on mercury emissions from the two ferroalloys production 

facilities since the 2011 proposal. In particular, we obtained 

data from each furnace and for each product type (ferromanganese 

and silicomanganese). While the mercury test data from the 2010 

ICR were collected using EPA Method 29 and the mercury test data 

from the 2012 ICR and other submitted test reports were 

collected using EPA Method 30B, the mercury test results from 

the two test methods were considered to be comparable and were 

used in the MACT Floor analysis. All of the test reports 

provided analytical results for mercury that were above the 

detection limit.

The raw materials used to produce ferroalloys contain 

various amounts of mercury, which is emitted during the smelting 

process. These mercury emissions are derived primarily from the 

manganese ore although there may be trace amounts in the coke or 

coal used in the smelting process. Some of the mercury that is 

in oxidized form is captured on the particulate matter (PM) and 

then collected in the particle control device (e.g., fabric 

filter or wet scrubber). In contrast, most of the gaseous 

elemental mercury is not captured by these particulate control 

devices and is largely emitted to the atmosphere. Based on the 
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available emissions test data, we estimate Eramet (which, as 

noted above, produces FeMn and SiMn) emits about 342 pounds per 

year of mercury from their furnaces and that Felman, which 

produces only SiMn, emits about 35 lb/yr of mercury from their 

furnaces. Pursuant to CAA section 112(d)(2) and 112(d)(3), we 

are proposing to revise the 1999 NESHAP to include emission 

limits for mercury.

b. Calculation of MACT Floor limits for mercury

With regard to determining appropriate MACT limits for 

mercury, importantly, the new test data confirm that

ferromanganese (FeMn) production has substantially higher 

mercury emissions compared to silicomanganese (SiMn) production

and that emissions are considerably higher at Eramet as compared 

to Felman. This finding is based on an analysis of the productspecific data sets. Furthermore, we evaluated differences in the 

processes and input materials to try to determine the reasons 

for the significant difference in mercury emissions. Based on 

this evaluation, we have determined the input material recipes 

for producing the different products are quite different. In the 

case of FeMn production, much more of the Mn ore and high carbon 

coke are used to reduce the MnO2 in the ore to Mn to produce 

FeMn. We conclude the difference in emissions of mercury is due 

to the significant differences in the input materials and recipe 
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for FeMn as compared to SiMn production.

Because of the significant differences in the input 

material and the mercury emissions between FeMn and SiMn, we 

determined that subcategories should be created for 

ferromanganese and silicomanganese production, with separate 

MACT limits for mercury proposed for each ferroalloys product

(FeMn and SiMn).

The MACT floor dataset for mercury from existing and new 

furnaces producing FeMn includes 6 test runs from a single 

furnace. As described above, this dataset (for the calculation 

of MACT limits for mercury from furnaces producing FeMn) was 

considered limited and therefore we followed the steps described 

in the Limited Dataset Memo to determine the appropriate MACT 

floor limits for mercury for furnaces producing FeMn. We first 

determined that the dataset is best represented by a normal 

distribution and ensured that we used the correct equation for 

the distribution. Because the floor for both existing and new 

furnaces is based on the performance of a single unit, our 

evaluation of the data was limited to ensuring that the emission 

limit is a reasonable estimate of the performance of the unit 

based on our knowledge about the process and controls. 

Accordingly, we compared the calculated emission limit to the 

highest measured value and the average short-term emissions from 
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the unit, and found that the calculated emission limit is about 

2.5 times the short-term average from the unit, which is within 

the range that we see when we evaluate larger data sets using 

our MACT floor calculation procedures. The fairly wide range in 

mercury emissions shown by the available data for this best 

performing unit indicate that variability is significant, and we 

determined that the emission limit is representative of the 

actual performance of the unit upon which the limit is based, 

considering variability. Therefore, we determined that no 

changes to our standard floor calculation procedure were 

warranted for this pollutant and subcategory, and we are 

proposing that the MACT floor is 170 μg/dscm for Hg from 

existing furnaces producing FeMn. We also note that while we 

calculated the same MACT floor value for new sources, we are 

proposing a beyond-the-floor standard for new sources, which is 

discussed later in this section of this preamble.

The MACT floor dataset for mercury from new furnaces 

producing SiMn includes 3 test runs from a single furnace 

(furnace #7 at Felman) that we identified as the best performing

unit based on average emissions. After determining that the 

dataset is best represented by a normal distribution and 

ensuring that we used the correct equation for the distribution, 

we evaluated the variance of this unit (furnace #7 at Felman). 
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Our analysis showed that this unit, identified as the best unit 

based on average emissions, also had the lowest variance, 

indicating consistent performance. Therefore, we determined that 

the emission limit reasonably accounts for variability and that 

no changes to the standard floor calculation procedure were 

warranted for this pollutant and subcategory, and we are 

proposing that the MACT floor is 4.0 μg/dscm for Hg from new 

furnaces producing SiMn. 

With regard to mercury emissions from existing furnaces 

producing SiMn, we have 12 test runs in our dataset. This data 

set was not determined to be a limited data set. Using the 99 

percent UPL method described above, we calculated the MACT floor 

limit (or 99 percent UPL) for exhaust mercury concentrations 

from existing furnaces producing SiMn to be 12 μg/dscm. 

The MACT floor limits for mercury for existing furnaces are

higher than the actual emissions measured during the ICR 

performance tests at each plant due to an allowance for 

variability reflected in the UPL. We anticipate that both of the 

existing sources would be able to meet these product-specific 

MACT Floor limits for existing sources without installing 

additional controls. Therefore, the costs and reductions for the 

MACT floor option were estimated to be zero because we conclude 
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that the facilities would be able to meet the mercury limits 

with their current furnace controls.

The next step in establishing MACT standards is the BTF

analysis. In this step, we investigate other mechanisms for 

further reducing HAP emissions that are more stringent than the 

MACT floor level of control in order to “require the maximum 

degree of reduction in emissions” of HAP. In setting such 

standards, section 112(d)(2) requires the Agency to consider the 

cost of achieving the additional emission reductions, any nonair quality health and environmental impacts and energy 

requirements. Historically, these factors have included factors 

such as solid waste impacts of a control, effects of emissions 

on bodies of water, as well as the energy impacts. 

c. Beyond the Floor analysis for mercury for existing furnaces

As described below, we considered BTF control options to 

further reduce emissions of mercury. The BTF mercury control 

options were developed assuming sub-categorization of furnace 

melting operations into ferromanganese production operations and 

silicomanganese production operations and installing activated 

carbon injection (ACI) technology with brominated carbon to 

control mercury emissions. 

The BTF mercury limits would be based on the estimated 

mercury emission reduction that can be achieved through the use 
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of ACI and brominated carbon. The bromine in the activated 

carbon can oxidize elemental mercury (Hg0) to oxidized mercury 

(Hg+2). The oxidized mercury is then suitable for capture on the 

activated carbon sorbent or further reacts with the bromine to 

produce mercuric bromide (HgBr2). Both the oxidized mercury and 

the mercuric bromide can be removed using a PM control device. 

It is generally accepted that the installation of ACI in 

conjunction with a fabric filter achieves at least 90 percent 

reduction of mercury.50

All three furnaces at Felman and one of the two furnaces at 

Eramet (Furnace #1) are equipped with a fabric filter system to 

reduce PM. The other furnace at Eramet (Furnace #12) controls PM

using a wet venturi scrubber. Limited data are available for 

mercury reduction using ACI with a venturi scrubber system, as 

described in the mercury control options memorandum.

51 However,

we identified one study conducted by the Minnesota Taconite 

Mercury Control Advisory Committee that evaluated mercury 

reductions from particulate scrubber systems and ACI.52 In 2011, 

 

50 Sargent & Lundy, IPM Model – Revisions to Cost and Performance for APC 

Technologies, Mercury Control Cost Development, Final, March 2013.

51 Memorandum from Bradley Nelson, EC/R to Phil Mulrine, EPA OAQPS/SPPD/MICG, 

Mercury Control Options and Impacts for the Ferroalloys Production Industry, 

March 16, 2014.

52 Michael E Berndt, Minnesota Department of Natural Resources, Division of 

Lands and Minerals, Minnesota Taconite Mercury Control Advisory Committee:

Summary of Phase One Research Results (2010-2012), November 29, 2012. 

http://files.dnr.state.mn.us/lands_minerals/reclamation/berndt_2012_final.pdf

.
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a field trial was conducted at Hibbing Taconite to demonstrate 

the effectiveness of brominated ACI in controlling mercury 

emissions from a taconite facility. The trial of the brominated 

ACI system was conducted in September and October 2011 and it

was determined that 75 percent Hg removal could be achieved with 

a brominated ACI rate of about 3 lb/MMacf (126 lb/hr) for the 

taconite iron ore processing sources. This 75 percent mercury 

reduction was demonstrated during a two-week continuous 

injection run in this study. The project also noted that better 

mercury removal results could be achieved with improved sorbent 

distribution. Therefore, although the ferroalloys production 

furnaces are different than the taconite production sources, we 

assume that the retrofit of ACI on the furnace at Eramet

controlled by a wet scrubber would achieve 50 percent additional 

mercury reduction beyond the level of control that the scrubber 

is currently achieving. Because of the lower potential mercury 

reductions expected for brominated carbon ACI and a venturi 

scrubber (compared to the reductions that would be achieved with 

use of ACI with fabric filters), we determined that a reduction

of 50 percent should be used in establishing the BTF mercury 

emissions limit to ensure that the limit could be achieved with 

brominated ACI on both furnaces at all times during FeMn 
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production. Therefore, the BTF limit for FeMn production for 

existing sources would be 82 μg/dscm. 

We estimated the capital costs, annualized costs, emissions 

reductions and cost effectiveness for the BTF limits for FeMn 

and SiMn production sources. The details regarding how these 

limits were derived and the estimated costs and expected 

reductions of mercury emissions by installing ACI controls, are 

provided in the Mercury Control Options and Impacts for the 

Ferroalloys Production Industry document which is available in 

the docket. 

Regarding the BTF control option for existing sources that 

produce ferromanganese, we estimated the costs and reductions 

based on the installation of ACI on Furnaces 1 and 12 at Eramet 

with operation only during the production of ferromanganese and

a polishing baghouse on Furnace 1. Other costs include labor, 

materials and waste disposal. The emissions and annual cost for 

this BTF control option are based on the assumption that both 

furnaces at Eramet produce ferromanganese 50 percent of the time 

annually and produce SiMn the other 50 percent of the year. We 

based this reasonable assumption on available information 

regarding production patterns for the 2 products at Eramet. The 

estimated mercury reduction that would be achieved at Furnace 1 

at Eramet (which is currently controlled with a baghouse) is 
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assumed to be 90 percent based on the installation of ACI and a 

new polishing baghouse. Regarding Furnace 12 at Eramet (which is 

currently controlled with a wet venturi scrubber), the mercury 

reductions that would be achieved with brominated ACI are 

assumed to be 50 percent. For the BTF control option for 

existing sources that produce ferromanganese, we estimate the 

capital costs would be about $30 million, annualized costs of 

about $3.3 million and would achieve about 191 pounds per year 

of reductions in mercury emissions, which results in estimated 

cost-effectiveness of about $17,600 per pound. All the costs and 

reductions would be at Eramet since Eramet is the only facility 

in the U.S. that produces FeMn.

As stated earlier the cost-effectiveness is estimated to be 

$17,600/lb. However, it is important to note that costeffectiveness is but one factor we consider in assessing the 

cost of the emission reduction at issue here. See NRDC v. EPA, 

749 F.3d 1055, 1060 (D.C. Cir. April 18, 2014) (“Section 112 

does not command EPA to use a particular form of cost 

analysis.”). We also consider other factors in assessing the

cost of the emission reduction as part of our beyond-the-floor 

analysis, including, but not limited to, total capital costs, 

annual costs and costs compared to total revenues (e.g., costs 

to revenue ratios). 
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As mentioned above, we estimate the capital costs would be 

about $30 million, annualized costs of about $3.3 million and

that all these costs would be for Eramet, which is the only 

facility in the United States that produces FeMn. Furthermore, 

we estimate the annual costs for BTF controls for mercury at 

Eramet (in addition to the costs for controls for fugitive HAP 

emissions required as part of the risk analysis explained later 

in this preamble) would be about 3 percent of revenues, which we 

believe is potentially significant given the facts at issue 

here. In addition, it is our understanding that for the past few 

years the plant has not made any profits. More details regarding 

the potential economic impacts of the BTF option are provided in 

the Economic Impact Analysis (EIA) for the Manganese Ferroalloys 

RTR Supplemental Proposal document which is available in the 

docket for this action.

We also evaluated an approach that could reduce the 

compliance costs of the BTF option. We considered the 

possibility that Eramet could potentially decide to produce FeMn 

in only one furnace and if so, would only need to install ACI 

for 1 furnace. If so, the costs for Eramet to comply with the 

BTF option could be significantly lower. This approach would 

reduce production flexibility, which could pose significant 

production issues for the company, but would allow Eramet to 
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avoid some of the emissions control costs under the BTF option. 

However, we realize there would likely be production issues and 

other issues, with this approach. Furthermore, we believe it 

would be inappropriate for the rule to essentially restrict 

production flexibility. Therefore for our cost impacts analysis 

of the BTF option we have assumed brominated ACI would be needed 

for both furnaces.

Based on the available economic information, assuming 

market conditions remain approximately the same, we believe 

Eramet Marietta would not be able to sustain the costs of BTF

mercury controls (in addition to the fugitive control costs

required as part of the risk analysis explained later in this 

preamble, in Section IV.C.).

53 This would likely result in 

substantial economic impacts in the short-term and potential 

closure of the facility in the longer-term. Since Eramet 

Marietta is the only facility in the United States which 

produces FeMn, closure of this facility would eliminate 100 

percent of the United States production of FeMn, which is an

important product for the steel industry. After considering all 

the factors described above, we are not proposing BTF limits for 

mercury for FeMn production.

 

53 As noted in our risk analysis explained later in this preamble, proposal 

of the MACT floor standard for mercury (along with the controls for fugitive 

manganese emissions, which are explained later in this preamble) provide an 

ample margin of safety to protect public health.
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We also evaluated possible BTF controls for existing SiMn 

production sources, which have much lower mercury emissions as 

compared to FeMn production. We estimated that the BTF option 

for SiMn would achieve an additional 60 pounds/year reductions

and that the cost-effectiveness would be about $109,000 per 

pound of mercury reduced for SiMn production, which we conclude 

is not cost-effective as a BTF option. Furthermore, based on our 

economic analyses, we believe that the Felman facility could be 

at potential risk of closure under this option, especially given 

that these costs would be in addition to the costs for 

controlling fugitive HAP metals emissions (such as Mn, As, Ni

and Cd). Therefore, we are not proposing BTF limits for mercury 

for SiMn production.

d. Beyond the Floor analysis for new and reconstructed furnaces

Regarding BTF controls for new or major reconstructed 

furnaces, we believe such sources would be constructed to 

include a baghouse as the primary PM control device (in order to 

comply with the proposed lower new source limits for PM) and 

then they could add ACI after the baghouse for mercury control 

along with a polishing baghouse and would achieve at least 90 

percent reduction. Therefore, the BTF limit for new FeMn 

production sources is calculated to be 17 μg/dscm. Regarding 
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SiMn, the BTF limit for new sources producing SiMn would be 1.2 

μg/dscm. 

The estimated costs for beyond the floor controls for 

mercury for new and reconstructed sources are based on the costs 

of installing and operating brominated ACI and a polishing 

baghouse. Based on this, we estimate that the cost effectiveness 

of BTF controls for a new and major reconstructed FeMn 

production source would be about $12,000/lb. Therefore, we 

conclude that BTF controls would be cost-effective and feasible 

for any new or major reconstructed furnace that produces FeMn.

Therefore we are proposing a limit of 17 μg/dscm for new or 

major reconstructed furnaces that produce FeMn. 

However, for a new SiMn production source, the cost 

effectiveness would be at least $51,000/lb. Therefore, we

believe BTF controls for new SiMn production sources would not 

be cost-effective. Furthermore, for SiMn production, as 

described above, the new source MACT floor limit is already low 

(i.e., 4.0 μg/dscm). Therefore we are proposing an emissions 

limit of 4.0 μg/dscm for new or major reconstructed SiMn 

production furnaces based on the new source MACT Floor.

e. Proposed limits for existing, new and reconstructed Sources

Based on all our analyses described above, we are proposing

mercury limits based on the MACT Floor (UPL) for each product 
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type (ferromanganese, silicomanganese) for existing furnaces;

BTF limits for mercury for new and reconstructed FeMn production 

furnaces; and mercury limits for new and reconstructed SiMn 

production furnaces based on the MACT Floor. These limits are 

summarized in Table 4.

Table 4. Summary of the Proposed Mercury Control Emissions

Limits (μg/dscm) from the Furnace Melting Processes

Proposed Mercury Controls

FeMn 

Production 

(existing 

sources)

FeMn 

Production (new 

and reconstructed 

sources)

SiMn 

Production 

(existing 

sources)

SiMn 

Production 

(new and 

reconstructed 

sources)

MACT Floor limits for FeMn 

and SiMn existing sources; 

BTF limit for new and 

reconstructed FeMn sources; 

and MACT floor limit for 

new and reconstructed SiMn 

sources

170 17 12 4.0

5. How did we develop proposed limits for Polycyclic Aromatic 

Hydrocarbons (PAHs)?

As described above, we obtained additional data on PAH 

emissions from the two ferroalloys production facilities since 

the 2011 proposal. In particular, we obtained data from each 

furnace and for each product type (FeMn and SiMn). We used the 

resulting dataset to re-evaluate the MACT floor limits and BTF

options. For more information on this analysis, see Revised MACT 

Floor Analysis for the Ferroalloys Production Source Category, 

which is available in the docket. 
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As in the case of the mercury analysis, our results show 

that there is a significant difference in PAH emissions during 

FeMn production as compared to SiMn production. Furthermore, 

similar to mercury, we conclude that this difference is due to 

significant differences in the recipe and input materials for 

FeMn compared to SiMn production.

Therefore, we determined that it would be appropriate to 

have two subcategories for PAH emissions and establish separate 

MACT limits for each of these two subcategories. 

The MACT floor dataset for PAHs from existing furnaces 

producing FeMn includes 6 test runs from 2 furnaces. As 

described above, this dataset (for the calculation of the MACT 

Floor limit for PAHs for FeMn production furnaces) was 

considered a limited dataset and therefore we followed the steps 

described in the Limited Dataset Memo to determine the 

appropriate MACT Floor limit for PAHs for these sources. This 

subcategory includes only two units, and the CAA specifies that 

the existing source MACT floor for subcategories with fewer than 

30 sources shall not be less stringent than “the average 

emission limitation achieved by the best performing 5 sources.” 

However, since there are only 2 units in the subcategory and we 

have data for both units, the data from both units serve as the 

basis for the MACT floor. After determining that the dataset is 
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best represented by a normal distribution and ensuring that we 

used the correct equation for the distribution, we considered

the selection of a lower confidence level for determining the 

emission limit by evaluating whether the calculated limit 

reasonably represents the performance of the units upon which it 

is based. In this case, where two units make up the pool of best 

performers, the calculated emission limit is about twice the 

short-term average emissions from the best performing sources, 

indicating that the emission limit is not unreasonable compared 

to the actual performance of the units upon which the limit is 

based and is within the range that we see when we evaluate 

larger datasets using our MACT floor calculation procedures. 

Therefore, we determined that no changes to our standard floor 

calculation procedure are warranted for this pollutant and 

subcategory, and we are proposing that the MACT floor is 1,400

μg/dscm for PAHs from existing furnaces producing FeMn. 

The MACT floor dataset for PAHs from new furnaces producing 

FeMn includes 3 test runs from a single furnace (furnace #12 at 

Eramet) that we identified as the best performing unit based on 

average emissions performance. After determining that the 

dataset is best represented by a normal distribution and 

ensuring that we used the correct equation for the distribution, 

we evaluated the variance of the best performing unit. Our 
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analysis showed that this unit, which was identified as the best 

unit based on average emissions, also had the lowest variance. 

Therefore, we determined that the emission limit would 

reasonably account for variability and that no changes to the 

standard floor calculation procedure were warranted for this 

pollutant and subcategory, and we are proposing that the MACT 

floor is 880 μg/dscm for PAHs from new furnaces producing FeMn. 

The MACT floor dataset for PAHs initially identified for 

new furnaces producing SiMn includes 6 test runs from a single

furnace (furnace #2 at Felman) that we identified as the best 

performing unit based on average emissions. After determining 

that the dataset is best represented by a normal distribution 

and ensuring that we used the correct equation for the 

distribution, we evaluated the variance of this unit (furnace #2

at Felman) and concluded that further consideration of the 

variance was warranted. In particular, we noted that the 

variance of the dataset for this unit was almost twice as large 

as the variance of the dataset for the pool of best performing 

units that was used to calculate the existing source MACT floor. 

The high degree of variance in the dataset for the unit with the 

lowest average prompted us to question whether this unit was, in 

fact, the best performing unit and to evaluate the dataset for 

the unit with the next lowest average (furnace #7 at Felman). 
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The dataset for furnace #7 includes 3 test runs, the furnaces 

are controlled with the same type of add-on control technology, 

and the average emissions from furnace #2 are only about 22 

percent lower than the average emissions from furnace #7. While 

we find the average performance of these 2 units to be similar, 

the unit with the higher average has a variance more than 2 

orders of magnitude lower than that of the unit with the lower 

average, thus indicating that the unit with the higher average 

has a far more consistent level of performance. The combination 

of components from the unit with the higher average (furnace #7) 

yields an emissions limit that is lower than that calculated 

from the dataset of the unit (furnace #2) with the lowest 

average (71.7 versus 132.8 μg/dscm). For these reasons, we 

determined that the unit with the lowest average (furnace #2) is 

not the best performing source for this pollutant and we are 

instead selecting furnace #7 as the best performing source. 

After selecting the source upon which the new source limit would 

be based, we next considered whether the selection of a 

different confidence level would be appropriate. In this case, 

we determined that a lower confidence level was not warranted 

given the small amount of variability in the data for the unit 

that we identified as the best performer. Based on the factors 

outlined above, we are proposing that the MACT floor is 72 
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μg/dscm for PAHs from new furnaces producing SiMn.

With regard to PAH emissions from existing furnaces 

producing SiMn, we have 18 test runs in our dataset. This 

dataset was not determined to be a limited data set. The UPL 

results for this dataset using a 99 percent confidence level was

determined to be 120 μg/dscm for SiMn production and was

determined to be the MACT floor limit for PAHs for existing 

furnaces producing SiMn.

Based on the data we received prior to summer 2014, we 

estimate that neither source would need to install additional 

controls to meet the MACT Floor emission limits described above.

However, as mentioned in Section II.D of today’s notice, we 

received additional PAH data in August 2014. We have not yet 

completed our review and technical analyses of those new data, 

and have not yet incorporated these new data into our analyses.

Nevertheless, we are seeking comments regarding the new PAH data 

and how these data could affect our analyses.

The current PM controls on both facilities capture some of 

PAH emissions. Nevertheless, we also considered BTF options for 

control of PAH emissions based on the additional reductions that 

could be achieved via control with ACI. Based on information 

from carbon vendors, an activated carbon system that is designed 

to achieve up to 90 percent reduction in mercury emissions 
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should also achieve significant reductions in PAH with no 

additional costs. However, significant uncertainties remain 

regarding the percent of reductions in PAHs that would be 

achieved with ACI. One study54 found that ACI can achieve 74-91 

percent reduction in PAH emissions depending on the 

concentration of activated carbon in the flue gas. Based on this 

information, we assume that ACI probably can achieve 75 percent 

reduction in PAH emissions from the furnace. Therefore, for our 

analysis of BTF options, we assumed an ACI system can achieve 75 

percent reduction of PAH emissions from the furnace exhaust. 

Based on this assumption, possible BTF limits for PAHs would be 

340 μg/dscm for FeMn production furnaces and 28 μg/dscm for SiMn

production furnaces. The estimated capital and annualized costs 

to achieve these BTF PAH limits are the same costs as those 

shown for mercury in the mercury control options memorandum. For 

FeMn production, the capital cost was calculated to be $30.2 

million and the annual cost was calculated to be $3.4 million 

and would only apply to the furnaces at Eramet and the estimated 

PAH reductions would be 2.35 tons per year, which results in 

cost-effectiveness of $1.4 million per ton of PAH. The capital 

cost for a beyond the floor PAH option for SiMn and FeMn 

 

54 Hong-Cang Zhou, Zhao-Ping Zhong, Bao-Sheng Jin, Ya-Ji Huang and Rui Xiao, 

Experimental study on the removal of PAHs using in-duct activated carbon 

injection, Chemosphere, November 17, 2004.
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production was calculated to be $41.7 million with an annual 

cost of $6.9 million and the estimated PAH reductions would be 

4.0 tons per year, which results in cost-effectiveness of $1.7 

million per ton, which we conclude is not cost-effective for 

PAHs. Given the uncertainties regarding the percent of PAH 

reductions that can be achieved with ACI and since the costeffectiveness is relatively high for this HAP, we are not 

proposing BTF limits for PAHs. Instead, we have determined that 

it is appropriate to propose PAH limits based on the MACT Floor 

level of control, therefore we are proposing a MACT limit of 

1,400 μg/dscm for PAHs for existing FeMn production furnaces and 

880 μg/dscm for PAHs for new and reconstructed FeMn production 

furnaces and we are proposing a MACT floor limit of 120 μg/dscm 

for PAHs for existing SiMn production furnaces and 72 μg/dscm 

for PAHs for new and reconstructed SiMn production furnaces.

Table 5. Proposed Emissions Limits (μg/dscm) for PAHs from the 

Furnace Melting Processes

FeMn Production 

(existing 

sources)

FeMn Production (new 

and reconstructed 

sources)

SiMn 

Production 

(existing 

sources)

SiMn 

Production 

(new and 

recon-structed 

sources)

Proposed Emissions 

Limits for PAHs 1400 880 120 72

6. How did we develop limits for Hydrochloric Acid (HCl)?

Like mercury and PAH, we obtained additional HCl test data 

since proposal. However, more than half the test results (20 of 
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the 36 test runs) were below the detection limit. This situation 

required the use of additional statistical analysis, as 

described in the Revised MACT Floor Analysis for the Ferroalloys 

Production Source Category, which is available in the docket. We 

determined the data set for HCl from furnace outlets has a nonnormal distribution. The non-normal distribution of the data is 

a result of the mix of analytical results reported above and 

below the detection limit and is not due to the type of product 

being produced (FeMn or SiMn) in the furnace. Therefore, for HCL 

we are not establishing subcategories based on product. An 

equation for log-normally distributed data was used to determine 

the UPL of the HCl dataset for both FeMn and SiMn production 

combined. The UPL for the log-normal dataset was calculated to 

be 1,100 μg/dscm. Because more than half of the dataset were

reported below the detection limit, using EPA procedures, three 

times the representative method detection level (RDL) for HCl 

(180 μg/dscm), was compared to the calculated UPL. The 

calculated UPL was higher and, thus, was selected as the MACT 

floor limit for existing furnaces. At this level, we expect 

neither source would need to install additional controls to meet 

the MACT floor emission limits.

The MACT floor dataset for HCl from new furnaces producing 

FeMn or SiMn includes 6 test runs from a single furnace (furnace 
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#5 at Felman) that we identified as the best performing unit 

based on average emissions. As described above, this dataset 

(for the calculation of the new source limit for HCL) was 

considered a limited dataset and therefore we followed the steps 

described in the Limited Dataset Memo to determine the 

appropriate MACT Floor limit for HCl for new furnaces. After 

determining that the dataset is best represented by a non-normal 

distribution and ensuring that we used the correct equation for 

the distribution, we evaluated the variance of this best 

performing unit. Our analysis showed that this unit, identified 

as the best unit based on average emission, also had the lowest 

variance, indicating consistent performance. Therefore, we 

determined that the emission limit reasonably accounts for 

variability and that no changes to the standard floor 

calculation procedure were warranted for this pollutant and 

subcategory. We also note that for this standard, the calculated 

new source floor level was below the level that can be 

accurately measured (the level that we refer to as “3 times the 

representative detection level” or 3xRDL). Therefore, we are 

proposing a new source MACT emission limit of 180 ppm for HCl, 

which is the 3xRDL value for HCl. 

No facilities in the source category use add-on control 

devices or work practices to limit emissions of HCl beyond what 
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is normally achieved as co-control of the emissions with 

particulate matter control device. Also, as explained above, 

there are a significant number of non-detects for HCl. Thus, 

emissions are already low. Nevertheless, we evaluated possible 

beyond the floor options to further reduce HCl to ensure our 

analyses were complete. The BTF analyses are described in the 

Revised MACT Floor Analysis for the Ferroalloys Production 

Source Category document which is available in the docket. We 

did not identify any appropriate BTF options for HCl.

Given the low emissions of HCl and the results of our 

analyses, we are not proposing beyond the floor limits for HCl. 

Therefore, in this supplemental proposal, we are proposing

emission limits for HCl of 1,100 μg/dscm for existing furnaces

and 180 μg/dscm for new or reconstructed furnaces, which are at 

the level of the MACT floors.

Table 6. Proposed Emissions Limits (μg/dscm) for HCl from the 

Furnace Melting Processes

FeMn and SiMn Production (existing sources)

FeMn and SiMn Production (new and reconstructed sources)

Proposed Emissions 

Limits for HCl 1100 180

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

1. Inhalation Risk Assessment Results

Table 7 of this preamble provides an overall summary of the 

results of the inhalation risk assessment.
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Table 7. Ferroalloys Production Source Category Inhalation 

Risk Assessment Results

Maximum 

Individual 

Cancer Risk 

(-in-1 million)a

Estimated 

Population at 

Increased Risk 

Levels of 

Cancer 

Estimated 

Annual Cancer 

Incidence 

(cases per

year)

Maximum 

Chronic 

Non-cancer 

TOSHIb

Maximum 

Screening 

Acute Noncancer HQc

Actual Emissions

20

≥ 1-in-1 

million: 31,000

≥ 10-in-1 

million: 400

≥ 100-in-1 

million: 0

0.002 4

HQREL = 1

(arsenic 

compounds, 

hydrofluoric 

acid, 

formaldehyde)

Allowable Emissionsd

100

≥ 1-in-1 

million: 94,000

≥ 10-in-1 

million: 2,500

≥ 100-in-1 

million: 0

0.005 40 -

a Estimated maximum individual excess lifetime cancer risk due to HAP 

emissions from the source category.

b Maximum TOSHI. The target organ with the highest TOSHI for the Ferroalloys 

Production source category for both actual and allowable emissions is the 

neurological system. The estimated population at increased levels of 

noncancer hazard is 1,500 based on actual emissions and 11,000 based on 

allowable emissions.

c See Section III.A.3 of this notice for explanation of acute dose-response 

values. Acute assessments are not performed on allowable emissions. 

d The development of allowable emission estimates can be found in the

memorandum titled Revised Development of the RTR Emissions Dataset for the 

Ferroalloys Production Source Category for the 2014 Supplemental Proposal, 

which is available in the docket.

The inhalation risk modeling performed to estimate risks 

based on actual and allowable emissions relied primarily on 

emissions data from the ICRs and calculations described in the 

Emissions Memo. The results of the chronic baseline inhalation 

cancer risk assessment indicate that, based on estimates of 
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current actual emissions, the maximum individual lifetime cancer 

risk (MIR) posed by the ferroalloys production source category 

is 20-in-1 million, with chromium compounds, PAHs and nickel 

compounds from tapping fugitives, furnace fugitives and a 

furnace accounting for 70 percent of the MIR. The total 

estimated cancer incidence from ferroalloys production sources 

based on actual emission levels is 0.002 excess cancer cases per 

year or one case every 500 years, with emissions of PAH, 

chromium compounds and cadmium compounds contributing 42 

percent, 18 percent and 15 percent, respectively, to this cancer 

incidence. In addition, we note that approximately 400 people 

are estimated to have cancer risks greater than or equal to 10-

in-1 million, and approximately 31,000 people are estimated to 

have risks greater than or equal to 1-in-1 million as a result 

of actual emissions from this source category.

When considering MACT-allowable emissions, the maximum 

individual lifetime cancer risk is estimated to be up to 100-in1 million, driven by emissions of arsenic compounds and cadmium 

compounds from the MOR process baghouse outlet. The estimated 

cancer incidence is estimated to be 0.005 excess cancer cases 

per year or one excess case in every 200 years. Approximately 

2,500 people are estimated to have cancer risks greater than or 

equal to 10-in-1 million and approximately 94,000 people are
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estimated to have cancer risks greater than or equal to 1-in-1 

million considering allowable emissions from ferroalloys 

facilities. 

The risk results described in this section and shown in 

Table 7 are based on the emissions data received prior to summer 

2014. These results do not reflect the new PAH, PM or mercury 

data we received in August 2014 (as described in Section II.D. 

in this notice). We seek comment on the new data, which are 

available in the docket for today’s action, and how these 

additional data would impact the risk assessment.

The maximum modeled chronic non-cancer HI (TOSHI) value for 

the source category based on actual emissions is estimated to be 

4, with manganese emissions from tapping fugitives accounting 

for 93 percent of the HI. Approximately 1,500 people are 

estimated to have exposure to HI levels greater than 1 as a 

result of actual emissions from this source category. When 

considering MACT-allowable emissions, the maximum chronic noncancer TOSHI value is estimated to be 40, driven by allowable 

emissions of manganese from the MOR process baghouse outlet. 

Approximately 11,000 people are estimated to have exposure to HI 

levels greater than 1 considering allowable emissions from these 

ferroalloys facilities. 

2. Acute Risk Results
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Our screening analysis for worst-case acute impacts based 

on actual emissions indicates the potential for three pollutants

– arsenic compounds, formaldehyde, and hydrofluoric acid – to 

have HQ values of 1, based on their respective REL value. Both 

facilities have estimated HQs of 1 for these pollutants.

To better characterize the potential health risks 

associated with estimated worst-case acute exposures to HAP from 

the source category at issue and in response to a key 

recommendation from the SAB’s peer review of the EPA’s section 

112(f) RTR risk assessment methodologies, we examine a wider 

range of available acute health metrics than we do for our 

chronic risk assessments. This is in acknowledgement that there 

are generally more data gaps and inconsistencies in acute 

reference values than there are in chronic reference values. By 

definition, the acute CalEPA REL represents a health-protective 

level of exposure, with no risk anticipated below those levels, 

even for repeated exposures; however, the health risk from 

higher-level exposures is unknown. Therefore, when a CalEPA REL 

is exceeded and an AEGL-1 or ERPG-1 level is available (i.e., 

levels at which mild effects are anticipated in the general 

public for a single exposure), we have used them as a second 

comparative measure. Historically, comparisons of the estimated 

maximum off-site 1-hour exposure levels have not been typically 
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made to occupational levels for the purpose of characterizing 

public health risks in RTR assessments. This is because 

occupational ceiling values are not generally considered 

protective for the general public since they are designed to 

protect the worker population (presumed healthy adults) for 

short-duration (less than 15-minute) increases in exposure. As a 

result, for most chemicals, the 15-minute occupational ceiling 

values are set at levels higher than a 1-hour AEGL-1, making 

comparisons to them irrelevant unless the AEGL-1 or ERPG-1 

levels are also exceeded. 

All the HAP in this analysis have worst-case acute HQ 

values of 1 or less, indicating that they carry no potential to 

pose acute concerns. In characterizing the potential for acute 

non-cancer impacts of concern, it is important to remember the 

upward bias of these exposure estimates (e.g., worst-case 

meteorology coinciding with a person located at the point of 

maximum concentration during the hour) and to consider the 

results along with the conservative estimates used to develop 

peak hourly emissions as described earlier, as well as the 

screening methodology. Refer to the document titled Revised 

Development of the RTR Emissions Dataset for the Ferroalloys 

Production Source Category for the 2014 Supplemental Proposal

(which is available in the docket for this action) for a 
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detailed description of how the hourly emissions were developed 

for this source category. 

3. Multipathway Risk Screening Results

Results of the worst-case Tier I screening analysis 

indicate that PB-HAP emissions (based on estimates of actual 

emissions) from one or both facilities in this source category 

exceed the screening emission rates for cadmium compounds, 

mercury compounds, dioxins and PAH. For the compounds and 

facilities that did not screen out at Tier I, we conducted a 

Tier II screen. The Tier II screen replaces some of the 

assumptions used in Tier I with site-specific data, including 

the land use around the facilities, the location of fishable 

lakes and local wind direction and speed. The Tier II screen 

continues to rely on high-end assumptions about consumption of 

local fish and locally grown or raised foods (adult female 

angler at 99th percentile consumption for fish55 and 90th

percentile for consumption of locally grown or raised foods56) 

and uses an assumption that the same individual consumes each of 

these foods in high end quantities (i.e., that an individual has 

high end ingestion rates for each food). The result of this 

 

55 Burger, J. 2002. Daily consumption of wild fish and game: Exposures of high 

end recreationists. International Journal of Environmental Health Research 

12:343-354.

56 U.S. EPA. Exposure Factors Handbook 2011 Edition (Final). U.S. 

Environmental Protection Agency, Washington, DC, EPA/600/R-09/052F, 2011.
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analysis was the development of site-specific emission rate 

screening levels for each PB-HAP. It is important to note that, 

even with the inclusion of some site-specific information in the 

Tier II analysis, the multi-pathway screening analysis is still 

a very conservative, health-protective assessment (e.g., upperbound consumption of local fish, locally grown and/or raised 

foods) and in all likelihood will yield results that serve as an 

upper-bound multi-pathway risk associated with a facility.

While the screening analysis is not designed to produce a 

quantitative risk result, the factor by which the emissions 

exceed the screening level serves as a rough gauge of the 

“upper-limit” risks we would expect from a facility. Thus, for 

example, if a facility emitted a PB-HAP carcinogen at a level 2 

times the screening level, we can say with a high degree of 

confidence that the actual maximum cancer risks will be less 

than 2-in-1 million. Likewise, if a facility emitted a noncancer 

PB-HAP at a level 2 times the screening level, the maximum 

noncancer hazard would represent an HQ less than 2. The high 

degree of confidence comes from the fact that the screens are 

developed using the very conservative (health-protective)

assumptions that we describe above.

Based on the Tier II screening analysis, no facility emits 

cadmium compounds above the Tier II screening levels. One 
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facility emits mercury compounds above the Tier II screening 

levels and exceeds that level by a factor of 9. Both facilities 

emit chlorinated dibenzodioxins and furans (CDDF) as 2,3,7,8-

tetrachlorodibenzo-p-dioxin toxicity equivalent (TEQ) above the 

Tier II screening levels and the facility with the highest 

emissions of dioxins exceeds its Tier II screening level by a 

factor of 20. Both facilities emit POM as benzo(a)pyrene TEQ 

above the Tier II screening levels and the facility with the 

highest emissions exceeds its screening level by a factor of 20. 

Polychlorinated biphenyls (PCB) are PB-HAP that do not 

currently have multi-pathway screening values and so are not 

evaluated for potential non-inhalation risks. These HAP however, 

are not emitted in appreciable quantities (estimated to be 

0.00026 tpy) from the ferroalloys source category and we do not 

believe they contribute to multi-pathway risks for this source 

category. 

Results of the analysis for lead indicate that based on the 

baseline, actual emissions, the maximum annual off-site ambient 

lead concentration was only 50 percent of the NAAQS for lead and

if the total annual emissions occurred during a 3-month period, 

the maximum 3-month rolling average concentrations would exceed 

the NAAQS. However, as shown later in this preamble, based on 

emissions estimated for the post-control scenario, the maximum 
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annual off-site ambient lead concentration was only 3 percent of 

the NAAQS for lead. If the total annual emissions occurred 

during a 3-month period, the maximum 3-month rolling average 

concentrations would be about 12 percent of the NAAQS for lead, 

indicating that there is no concern for multi-pathway risks due 

to lead emissions.

4. Multipathway Refined Risk Results

A refined multipathway analysis was conducted for one 

facility in this source category using the TRIM.FaTE model. The 

facility, Eramet Marietta Incorporated, in Marietta, Ohio, was 

selected based upon its close proximity to nearby lakes and 

farms as well as having the highest potential multipathway risks 

for three of the four PB-HAP based on the Tier II analysis. 

These three PB-HAP were cadmium, mercury and PAHs. (Even though 

neither facility exceeded the Tier II screening levels for 

cadmium, Eramet had the higher value.) Eramet also emits 

dioxins, but the other facility had a higher exceedance of its

Tier II screening level. The refined analysis was conducted on 

all four PB-HAP. The refined analysis for this facility showed 

that the Tier II screen for each pollutant over-predicted the 

potential risk when compared to the refined analysis results. 

Overall, the refined analysis predicts a potential lifetime 

cancer risk of 10-in-1 million to the maximum most exposed 
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individual due to exposure to dioxins and PAHs. The non-cancer 

HQ is predicted to be below 1 for cadmium compounds and 1 for 

mercury compounds. 

Further details on the refined multipathway analysis can be 

found in Appendix 10 of the Residual Risk Assessment for the 

Ferroalloys Production Source Category in Support of the 

September 2014 Supplemental Proposal, which is available in the 

docket. 

5. Environmental Risk Screening Results

As described in Section III.A, we conducted an 

environmental risk screening assessment for the ferroalloys 

source category. In the Tier I screening analysis for PB-HAP the 

individual modeled Tier I concentrations for one facility in the 

source category exceeded some sediment, fish – avian piscivorus

and surface soil benchmarks for PAHs, methylmercury and mercuric 

chloride. Therefore, we conducted a Tier II assessment. 

In the Tier II screening analysis for PAHs and 

methylmercury none of the individual modeled concentrations for 

any facility in the source category exceeded any of the 

ecological benchmarks (either the LOAEL or NOAEL). For mercuric 

chloride, soil benchmarks were exceeded for some individual 

modeled points that collectively accounted for 5 percent of the 

modeled area. However, the weighted average modeled 
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concentration for all soil parcels was well below the soil 

benchmarks. 

 For HCl, each individual concentration (i.e., each off-site 

data point in the modeling domain) was below the ecological 

benchmarks for all facilities. The average modeled HCl 

concentration around each facility (i.e., the average 

concentration of all off-site data points in the modeling 

domain) did not exceed any ecological benchmark.

6. Facility-wide Risk Assessment Results

For both facilities in this source category, there are no 

other HAP emissions sources present beyond those included in the 

source category. Therefore, we conclude that the facility-wide 

risk is the same as the source category risk and that no 

separate facility-wide analysis is necessary.

7. Demographic Analysis Results

To examine the potential for any environmental justice (EJ) 

issues that might be associated with the source category, we 

performed a demographic analysis, which is an assessment of 

risks to individual demographic groups, of the population close 

to the facilities. In this analysis, we evaluated the 

distribution of HAP-related cancer risks and non-cancer hazards 
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from the ferroalloys production source category across different 

social, demographic and economic groups within the populations 

living near facilities identified as having the highest risks. 

The methodology and the results of the demographic analyses are 

included in a technical report, Risk and Technology Review –

Analysis of Socio-Economic Factors for Populations Living Near 

Ferroalloys Facilities, which is available in the docket for 

this action.

The results of the demographic analysis are summarized in 

Table 8 below. These results, for various demographic groups, 

are based on the estimated risks from actual emissions levels 

for the population living within 50 km of the facilities. 

Table 8. Ferroalloys Production Demographic Risk Analysis 

Results

Nationwide

Population with 

Cancer Risk at 

or Above 1-in-1 

Million Due to 

Ferroalloys 

Production

Population with 

Chronic Hazard 

Index Above 1

Due to 

Ferroalloys 

Production

Total 

Population

312,861,265 31,283 1,521

Race by Percent

White 72 96 99

All Other 

Races 28 4 1

Race by Percent

White 72 96 99

African 

American 13 1 0

Native 

American 1

0 0

Other and 

Multiracial 14 2 1
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Ethnicity by Percent

Hispanic 17 1 1

Non-Hispanic 83 99 99

Income by Percent

Below Poverty 

Level 14 15 7

Above Poverty 

Level 86 85 93

Education by Percent

Over 25 and 

without High 

School 

Diploma

15 11 11

Over 25 and 

with a High 

School 

Diploma

85 89 89

The results of the ferroalloys production source category 

demographic analysis indicate that emissions from the source 

category expose approximately 31,000 people to a cancer risk at 

or above 1-in-1 million and approximately 1,500 people to a 

chronic non-cancer TOSHI greater than 1 (we note that many of 

those in the first risk group are the same as those in the 

second). The percentages of the at-risk population in each 

demographic group (except for White and non-Hispanic) are 

similar to or lower than their respective nationwide 

percentages. Implementation of the provisions included in this 

proposal is expected to significantly reduce the number of 

people estimated to have a cancer risk greater than 1-in-1 

million due to HAP emissions from these sources from 31,000 

people to about 6,600 people. Implementation of the provisions 
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included in the proposal also is expected to reduce the number 

of people estimated to have a chronic non-cancer TOSHI greater 

than 1 from 1,500 people to no people with a TOSHI greater than 

1. 

C. What are our proposed decisions regarding risk acceptability,

ample margin of safety and adverse environmental effects based 

on our revised analyses?

1. Risk Acceptability 

As noted in Section II.A.1 of this preamble, the EPA sets 

standards under CAA section 112(f)(2) using “a two-step 

standard-setting approach, with an analytical first step to 

determine an ‘acceptable risk’ that considers all health 

information, including risk estimation uncertainty and includes 

a presumptive limit on maximum individual lifetime risk (MIR) of 

approximately 1 in 10 thousand[57].” (54 FR 38045, September 14, 

1989).

In this proposal, the EPA estimated risks based on both 

actual and allowable emissions from ferroalloy facilities. In 

determining acceptability, we considered risks based on both 

actual and allowable emissions. 

 

57 1-in-10 thousand is equivalent to 100-in-1 million. The EPA currently 

describes cancer risks as ‘n-in-1 million.’
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a. Estimated Risks from Actual Emissions

The baseline inhalation cancer risk to the individual most 

exposed to emissions from sources in the ferroalloys source 

category is 20-in-1 million based on actual emissions. The 

estimated incidence of cancer due to inhalation exposures is 

0.002 excess cancer cases per year, or 1 case every 500 years. 

Approximately 31,000 people face an increased cancer risk 

greater than 1-in-1 million due to inhalation exposure to actual 

HAP emissions from this source category and approximately 400 

people face an increased risk greater than 10-in-1 million and 

up to 20-in-1 million. The agency estimates that the maximum 

chronic non-cancer TOSHI from inhalation exposure is 4, with 

manganese emissions from tapping fugitives accounting for a 

large portion (93 percent) of the HI. 

The Tier II multipathway screening analysis of actual 

emissions indicated the potential for PAH emissions that are 

about 20 times the screening level for cancer, dioxin emissions 

that are about 20 times the screening level for cancer and 

mercury emissions that are 9 times above the screening level for 

non-cancer. 

As noted above, the Tier II multipathway screen is 

conservative in that it incorporates many health-protective 

assumptions. For example, the EPA chooses inputs from the upper 
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end of the range of possible values for the influential 

parameters used in the Tier II screen and assumes that the 

exposed individual exhibits ingestion behavior that would lead 

to a high total exposure. A Tier II exceedance cannot be equated 

with a risk value or a HQ or HI. Rather, it represents a highend estimate of what the risk or hazard may be. For example, an 

exceedance of 2 for a non-carcinogen can be interpreted to mean 

that we have high confidence that the HI would be lower than 2. 

Similarly, an exceedance of 30 for a carcinogen means that we 

have high confidence that the risk is lower than 30-in-1-

million. Confidence comes from the conservative, or healthprotective, assumptions that are used in the Tier II screen.

The refined multipathway analysis that the EPA conducted 

for one specific facility showed that the Tier II screen for 

each pollutant over-predicted the potential risk when compared 

to the refined analysis results. That refined multipathway 

assessment showed that the Tier II screen resulted in estimated 

risks that are higher than the risks estimated by the refined 

analysis by 3 times for PAH, 2 times for dioxins, and 6 times 

for cadmium. The HQ for mercury went from 9 in Tier II to 1. 

The screening assessment of worst-case acute inhalation 

impacts from baseline actual emissions indicates that all 

pollutants have HQ values of 1 or less, based on their 
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respective REL values. Considering the conservative, healthprotective nature of the approach that is used to develop these 

acute estimates, it is highly unlikely that an individual would 

have an acute exposure above the REL. Specifically, the analysis 

is based on the assumption that worst-case emissions and 

meteorology would coincide with a person being at the exact 

location of maximum impact for a period of time long enough to 

have an exposure level above the conservative REL value. The 

fact that the facilities in this source category are not located 

in areas that naturally lead to people being near the fence line 

for periods of time indicates that the exposure scenario used in 

the screening assessment would be unlikely to occur.

b. Estimated Risks from Allowable Emissions

The EPA estimates that the baseline inhalation cancer risk 

to the individual most exposed to emissions from sources in the 

ferroalloys source category is up to 100-in-1 million based on 

allowable emissions, with arsenic and cadmium emissions driving 

the risks. The EPA estimates that the incidence of cancer due to 

inhalation exposures could be up to 0.005 excess cancer cases 

per year, or 1 case approximately every 200 years. About 94,000 

people could face an increased cancer risk greater than 1-in-1 

million due to inhalation exposure to allowable HAP emissions 

from these source categories and approximately 2,500 people 
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could face an increased risk greater than 10-in-1 million and up 

to 100-in-1 million due to allowable emissions.

The risk assessment estimates that the maximum chronic noncancer TOSHI from inhalation exposure values is up to 40, driven 

by allowable manganese emissions. Approximately 11,000 people 

are estimated to have exposure to HI levels greater than 1.

c. Acceptability Determination

In determining whether risks are acceptable for this source 

category, the EPA considered all available health information 

and risk estimation uncertainty as described above. 

The risk results indicate that the allowable inhalation 

cancer risks to the individual most exposed are up to but no 

greater than approximately 100–in-1 million, which is the 

presumptive limit of acceptability. The MIR based on actual 

emissions is 20-in-1 million, well below the presumptive limit.

The maximum chronic exposure to manganese exceeds the human 

health dose-response value for manganese by a factor of 

approximately 4 based on actual emissions. For allowable 

emissions, exposures could exceed the health value up to a 

factor of approximately 40. The noncancer hazard is driven by 

manganese emissions. 

Neither the acute risk nor the risks from the multipathway 

assessment exceeded levels of concern, however the EPA does note 
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that the refined multipathway exposure estimate for mercury was 

at the level of the RfD.

The EPA proposes that the risks are unacceptable for the 

following reasons. First, the EPA considered the fact that the 

noncancer hazard quotient ranges from 4 based on actual 

emissions to 40 based on allowable emissions. The EPA has not 

established under section 112 of the CAA a numerical range for 

risk acceptability for noncancer effects as it has with 

carcinogens, nor has it determined that there is a bright line 

above which acceptability is denied. However, the Agency has 

established that, as exposure increases above a reference level 

(as indicated by a HQ or TOSHI greater than 1), confidence that 

the public will not experience adverse health effects decreases

and the likelihood that an effect will occur increases. For the 

ferroalloys source category, the potential for members of the 

public to be exposed to manganese at concentrations up to 40 

times the MRL reduces the Agency’s confidence that the public is 

protected from adverse health effects and diminishes the 

Agency’s ability to determine that such exposures are 

acceptable. Second, the EPA considered the fact that the cancer 

risk estimate for actual emissions is 20-in-1 million and up to 

100-in-1 million for allowable emissions. While 20-in-1 million 

is well within the acceptable range, risks from allowable 
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emissions are at the upper end of the range of acceptability. 

This fact, combined with the fact that the noncancer hazard is 

up to 40 times the MRL and the refined multipathway HQ for 

mercury is at the RfD, leads the agency to conclude that the 

risk from this source category is unacceptable.

2. Proposed Controls to Address Unacceptable Risks

a. Stack Emissions

 In order to address the unacceptable risk from this source 

category, we evaluated the potential to reduce MACT-allowable 

stack emissions, which resulted in a cancer MIR of 100-in-1

million, primarily due to allowable stack emissions of arsenic

and cadmium and contributed significantly to the chronic 

noncancer TOSHI of 40, primarily due to allowable stack 

emissions of manganese. Our analysis determined that we could 

lower the existing particulate matter emission limits by 

approximately 50 percent for furnace stack emissions, by 80 

percent for crushing and screening stack emissions and by 98 

percent for the metal oxygen refining (MOR) process, which would 

help reduce risk to an acceptable level. As explained above, the 

MOR is a major driver of the allowable risks. Therefore, by 

lowering the MOR limit by 98 percent, this results in a large 

reduction in the allowable risks.

For the reasons described above, under the authority of CAA 
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section 112(f)(2), we propose particulate matter emission limits 

for the stacks at the following levels: 4.0 mg/dscm for new or 

reconstructed electric arc furnaces and 25 mg/dscm for existing 

electric arc furnaces. In the 2011 proposal, we proposed a limit 

of 3.9 mg/dscm for any new, reconstructed or existing MOR 

process and 13 mg/dscm for any new, reconstructed or existing 

crushing and screening equipment. We believe sources can achieve 

the limits we are proposing today with existing controls. These 

emissions limits will substantially reduce potential risks due 

to allowable emissions from the stacks. We propose that 

compliance for all existing and new sources will be demonstrated 

by periodic stack testing, along with installation and 

continuous operation of bag leak detection systems for both new 

and existing sources that have baghouses, and continuous 

monitoring of liquid flow rate and pressure drop for sources

controlled with wet scrubbers. 

b. Process Fugitive Emissions Sources

 Process fugitive sources are partially controlled by the 

existing MACT rule via a shop building opacity standard; 

however, that standard was only intended to address tapping 

process fugitives generated under “normal” tapping process 

operating conditions. Casting and crushing and screening process 

fugitives in the furnace building were not included. Under the 
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authority of section 112 of the Act, which allows the use of 

measures to enclose systems or processes to eliminate emissions 

and measures to collect, capture or treat such pollutants when 

released from a process, stack, storage, or fugitive emissions 

point, we evaluated options to achieve improved emissions 

capture. In the 2011 proposal, we proposed full-enclosure with 

negative pressure and viewed local capture as not being an 

appropriate method of risk reduction. However, based on comments 

and other information gathered since the 2011 proposal and after 

further review and analyses of available information, we 

reevaluated whether the necessary risk reduction could be 

accomplished by an alternative approach to control fugitive 

emissions based on enhanced local capture of emissions. This 

control approach would include a combination of primary and 

secondary hoods that effectively capture process fugitive 

emissions and vents those emissions to PM control devices. The 

secondary capture would include hooding at the roof-lines

whereby remaining fugitives are collected and vented to control 

devices. As described further under the technology review 

section of this preamble, this approach (based on enhanced local 

capture and control of process fugitives, using primary and 

secondary hoods), will effectively reduce process fugitive

emissions. We conclude that this approach will achieve 
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substantial reductions of process fugitive emissions

(approximately 95 percent capture and control of fugitive 

emissions) and will also substantially reduce the estimated 

risks due to these emissions. Therefore, under section 112(f) of 

the CAA we are proposing this control option that is based on 

enhanced capture of fugitive emissions using primary hoods (that 

capture process fugitive emissions near the source) and 

secondary capture of fugitives (which would capture remaining 

fugitive emissions near the roof-line) and includes a tight 

opacity limit of 8 percent to ensure fugitives are effectively 

captured and controlled. We are proposing that the facilities in 

this source category must install and maintain a process 

fugitives capture system that is designed to capture and control 

95 percent or more of the process fugitive emissions. This is 

the same exact control approach described in more detail under 

the technology review section of today’s notice and the same 

control approach that we are proposing under section 112(d)(6)

of the Act, as described below. We estimate that this control 

approach will achieve about 95 percent capture of process 

fugitive emissions and will achieve about 77 tpy reduction in 

HAP metals emissions and will substantially reduce risks due to 

process fugitive emissions. We conclude that achieving these 

reductions is the level of control needed to address the 
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unacceptable risks due to HAP emissions from the source 

category.

c. Results of the Post-control Risk Assessment

The results of the post-control chronic inhalation cancer 

risk assessment indicate that the maximum individual lifetime 

cancer risk posed by these two facilities, after the 

implementation of the proposed controls, could be up to 10-in-1 

million, reduced from 20-in-1 million (i.e., pre-controls), with 

an estimated reduction in cancer incidence to 0.001 excess 

cancer cases per year, reduced from 0.002 excess cancer cases 

per year. In addition, the number of people estimated to have a 

cancer risk greater than or equal to 1-in-1 million would be 

reduced from 31,000 to 6,600. The results of the post-control 

assessment also indicate that the maximum chronic noncancer 

inhalation TOSHI value would be reduced to 1, from the baseline 

estimate of 4. The number of people estimated to have a TOSHI 

greater than 1 would be reduced from 1,500 to 0. We also 

estimate that after the implementation of controls, the maximum 

worst-case acute HQ value would be reduced from 1 to less than 1

(based on REL values). 

Considering post-control emissions of multipathway HAP, 

mercury emissions would be reduced by approximately 3 lbs/yr,

lead would be reduced by about 1,600 lbs/yr, POM emissions would 
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be reduced by approximately 5,200 lbs/yr, cadmium would be 

reduced by about 150 lbs/yr and dioxins and furans would be 

reduced by about 0.002 lbs/yr from the baseline emission rates.

3. Ample Margin of Safety Analysis

Under the ample margin of safety analysis, we again 

consider all of the health factors evaluated in the 

acceptability determination and evaluate the cost and 

feasibility of available control technologies and other measures 

(including the controls, measures and costs reviewed under the 

technology review) that could be applied in this source category 

to further reduce the risks due to emissions of HAP identified 

in our risk assessment.

We estimate that the actions proposed under CAA section 

112(f)(2), as described above to address unacceptable risks, 

will reduce the MIR associated with arsenic, nickel, chromium

and PAHs from 20-in-1 million to 10-in-1 million for actual 

emissions. The cancer incidence will be reduced from 0.002 to 

0.001 cases per year and the number of people estimated to have 

cancer risks greater than 1-in-1 million will be reduced, from 

31,000 people to 6,600 people. The chronic noncancer inhalation 

TOSHI will be reduced from 4 to 1 and the number of people 

exposed to a TOSHI level greater than 1 will be reduced from 

1,500 people to 0. In addition, the potential multipathway 
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impacts will be reduced.

Based on all of the above information, we conclude that the 

risks after implementation of the proposed controls are 

acceptable. Based on our research and analysis, we did not 

identify any cost-effective controls beyond those proposed above 

that would achieve further reduction in risk. While in theory 

the 2011 proposed approach of total enclosure would provide some 

additional risk reduction, the additional risk reduction is 

minimal and, as noted, we have substantial doubts that it would 

be feasible for these facilities. Therefore we conclude that the 

controls to achieve acceptable risks (described above) will also 

provide an ample margin of safety to protect public health.

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

technology review?

1. Metal HAP Emissions Limits from Stacks

As mentioned in the previous section, the available test 

data from the five furnaces located at two facilities indicate 

that all of these furnaces have PM emission levels that are well 

below their respective emission limits (the emission limits are 

based on size and product being produced in the furnace) in the 

1999 MACT rule. These findings demonstrate that the add-on 

emission control technologies (venturi scrubber, positive 

pressure fabric filter, negative pressure fabric filter) used to 
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control emissions from the furnaces are quite effective in 

reducing particulate matter (used as a surrogate for metal HAP) 

and that all of the facilities have emissions well below the 

current limits.

Under section 112(d)(6) of the Clean Air Act (CAA), we are 

required to revise emission standards, taking into account 

developments in practices, processes and control technologies.

The particulate matter (PM) emissions, used as a surrogate for 

metal HAP, that were reported by the industry in response to the 

2010 ICR were far below the level specified in the current 

NESHAP, indicating improvements in the control of PM emissions 

since promulgation of the current NESHAP. We re-evaluated the 

data received in 2010, along with additional data received in 

2012 and 2013, to determine whether it is appropriate to propose 

revised emissions limits for PM from the furnace process vents.

The re-evaluation of the PM limits was completed using available 

PM emissions test data from all the furnaces and consideration 

of variability across those data. More details regarding the 

available PM data and this re-evaluation are provided in the 

Revised Technology Review for the Ferroalloys Production Source 

Category for the Supplemental Proposal, which is available in 

the docket. Unlike PAH and mercury stack data, we did not see 

significant differences in variability of the PM data sets 
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depending on product produced (e.g., ferromanganese or 

silicomanganese). Therefore, we are not proposing to 

subcategorize the PM stack limits based on product type.

Based on this analysis, we determined that it is 

appropriate to propose revised PM limits for the furnaces and 

that the revised existing source furnace stack PM emissions 

limit should be 25 milligrams per dry standard cubic meter 

(mg/dscm). Therefore, we are proposing a revised emissions limit 

of 25 mg/dscm for existing furnace stack PM emissions in this 

supplemental proposal. This emission limit is slightly higher 

than the existing source furnace PM emission limit of 24 mg/dscm 

that we proposed in the 2011 proposal. The revised emissions 

limit is based on more data than the previous proposed limit. No 

additional add-on controls are expected to be required by the 

facilities to meet the revised existing source limit of 25

mg/dscm. However, this revised limit would result in 

significantly lower “allowable” PM emissions from the source 

category compared to the level of emissions allowed by the 1999 

MACT rule and would help prevent any emissions increases. To 

demonstrate compliance, we propose these sources would be 

required to conduct periodic performance testing and develop and 

operate according to a baghouse operating plan or continuously 

monitor venturi scrubber operating parameters. We also propose 
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that furnace baghouses would be required to be equipped with bag 

leak detection systems (BLDS).

The revised new source PM standard for furnaces was 

determined by evaluating the available data from the best 

performing furnace (which was determined to be furnace #2 at 

Felman). The new source MACT limit was determined to be 4.0

mg/dscm based on data from furnace #2 and was selected as the 

proposed MACT emissions limit for PM from new and reconstructed 

source furnace stacks.

The PM emission limit for the local ventilation control 

device outlet was also re-evaluated using compliance test data 

and test data from the 2012 ICR. A local ventilation control 

device is used to capture tapping, casting, or ladle treatment 

emissions and direct them to a control device other than one 

associated with the furnace. The 2011 proposal included a 

proposed PM limit for the local ventilation control device that 

was based on PM data from the furnaces. After the 2011 proposal, 

we received test data from 3 different emissions tests (for a 

total of 9 test runs) specifically for this local ventilation 

source. We determined these data were more appropriate for the 

development of a limit for this source than the furnace data we 

had used for the 2011 proposal. There is currently only one 
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local ventilation control device outlet emissions source in this 

source category.

Using the new data for the one existing local ventilation 

source, we calculated a revised emissions limit of 4.0 mg/dscm

and determined that this was an appropriate emissions limit for 

this source. Therefore we are proposing this emissions limit of 

4.0 mg/dscm for existing, new and reconstructed local 

ventilation control device emissions sources.

2. Metal HAP Emissions from Process Fugitives

In the 2011 proposal, we concluded that a proposed 

requirement for sources to enclose the furnace building, collect 

fugitive emissions such that the furnace building is maintained 

under negative pressure and duct those emissions to a control 

device represented an advance in emissions control measures 

since the Ferroalloys Production NESHAP was originally 

promulgated in 1999. Commenters on the 2011 proposal disagreed

with our assessment. Based on these comments, we reassessed the 

proposed requirement for negative pressure ventilation and 

determined that the installation and operation of the proposed 

system may not be feasible and would likely be very costly. For 

example, the recent secondary lead NESHAP requires use of such a 

system, but we recognize that a much smaller volume of air must 

be evacuated at secondary lead facilities because of their 
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smaller size compared to ferroalloy facilities. We agree that we 

had underestimated the costs of such negative pressure systems

and we have provided updated cost analyses. 

Commenters also raised concerns about worker safety and 

comfort in designing and operating such systems based on 

historical examples. We believe that such issues can be overcome 

with proper ventilation design and installation of air 

conditioning systems and other steps to ensure these issues are 

not a problem. However, after further review and evaluation we 

conclude that it would be quite costly for these facilities to 

become fully enclosed with negative pressure and achieve the 

appropriate ventilation and conditioning of indoor air. 

Going back to the original goal of identifying advances in 

emissions control measures since the Ferroalloys Production 

NESHAP was promulgated in 1999, we have arrived at a different 

conclusion than we described in the 2011 proposal. We reevaluated the costs and operational feasibility associated with 

the full building enclosure with negative pressure that we 

proposed in 2011. We consulted with ventilation experts who have 

worked with hot process fugitives similar to those found in the 

ferroalloys industry (e.g., electric arc furnace steel minimills and secondary lead smelters). We determined that 

substantially more air flow, air exchanges, ductwork, fans and 
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control devices and supporting structural improvements would be 

needed (compared to what we had estimated in the 2011 proposal) 

to achieve negative pressure and also ensure adequate 

ventilation and air quality in these large furnace buildings. 

Therefore, we determined that the proposed negative pressure 

approach presented in the 2011 proposal would be much more 

expensive than what we had estimated in 2011 and may not be 

feasible for these facilities.

We also evaluated another option based on enhanced capture 

of the process fugitive emissions using a combination of 

effective local capture with primary hooding close to the 

emissions sources and secondary capture of remaining fugitives 

with roof-line capture hoods and control devices. These 

buildings are currently designed such that fugitive emissions 

that are not captured by the primary hoods flow upward with a 

natural draft to the open roof vents and are vented to the 

atmosphere uncontrolled. Under our enhanced control scenario, 

the primary capture close to the emissions sources would be 

significantly improved with effective local hooding and 

ventilation and the remaining fugitive emissions (that are not 

captured by the primary hoods) would be drawn up to the roofline and captured with secondary hooding and vented to control 

devices. 
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In cases where additional collection of fugitives from the 

roof monitors is needed to comply with building opacity limits, 

fume collection areas may be isolated via baffles (so the area 

above the furnace where fumes collect may be kept separated from 

“empty” spaces in large buildings) and roof monitors over fume 

collection areas can be sealed and directed to control devices. 

The fugitive emission capture system should achieve inflow at 

the building floor, but outflow toward the roof where most of 

the remaining fugitives would be captured by the secondary 

hooding. We conclude that a rigorous, systematic examination of 

the ventilation requirements throughout the building is the key 

to developing a fugitive emission capture system (consisting of 

primary hoods, secondary hoods, enclosures and/or building 

ventilation ducted to particulate matter control devices) that 

can be designed and operated to achieve very low levels of 

fugitive emissions. Such an evaluation considers worker health, 

safety and comfort and it is designed to optimize existing 

ventilation options (fan capacity and hood design) and add 

additional capture options to meet specified design criteria 

determined through the evaluation process. Thus, we conclude 

that an enhanced capture system based on these design principles 

does represent an advancement in technology. We estimate that 

this control scenario would capture about 95 percent of the 
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process fugitive emissions and vent those emissions to PM 

control devices. This enhanced local capture option is described

in more detail in the Revised Technology Review document and in 

the Cost Impacts of Control Options to Address Fugitive HAP 

Emissions for the Ferroalloys Production NESHAP Supplemental 

Proposal document (Cost Impacts document) which are available in 

the docket.

Under this control option, the cost elements vary by plant 

and furnace and include the following:

 Curtains or doors surrounding furnace tops to contain 

fugitive emissions;

 Improvements to hoods collecting tapping emissions;

 Upgrade fans to improve the airflow of fabric filters 

controlling fugitive emissions;

 Addition of “secondary capture” or additional hoods to 

capture emissions from tapping platforms or crucibles;

 Addition of fugitives capture for casting operations;

 Improvement of existing control devices or addition of 

fabric filters; and

 Addition of rooftop ventilation, in which fugitive 

emissions escaping local capture are collected in the 

roof canopy over process areas through addition of 
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partitions, hoods, and then directed through ducts to 

control devices.

We estimate the total capital costs of installing the 

required ductwork, fans and control devices under the enhanced 

capture option (which is described above and in more detail in 

the Cost Impacts document) to be $37.6 million and the total 

annualized cost to be $7.1 million for the two plants. We 

estimate that this option would reduce metal HAP emissions by 75 

tons per year, resulting in a cost per ton of metal HAP removed 

to be $94,600 per ton ($47 per pound). The total estimated HAP 

reduction for the enhanced capture option is 77 tons per year at 

a cost per ton of $91,900 ($46 per pound). We also estimate that 

this option would achieve PM emission reductions of 229 tons per 

year, resulting in cost per ton of PM removed of $30,900 per ton 

and achieve PM2.5 emission reductions of 48 tons per year, 

resulting in a cost per ton of PM2.5 removal of $147,000 per ton.

We believe these controls for process fugitive HAP emissions 

(described above), which are based on enhanced capture (with 

primary and secondary hooding) are feasible for the Ferroalloys 

Production source category from a technical standpoint and are 

cost effective. This cost effectiveness is in the range of cost 

effectiveness for PM and HAP metals from other previous rules. 

However, it is important to note that there is no bright line 
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for determining cost-effectiveness for HAP metals. Each 

rulemaking is different and various factors must be considered. 

Some of the other factors we consider when making decisions 

whether to establish standards beyond the floor under section 

112(d)(2) or under section 112(d)(6) include, but are not 

limited to, the following: which of the HAP metals are being 

reduced and by how much; total capital costs; annual costs; and 

costs compared to total revenues (e.g., costs to revenue 

ratios). 

We also re-evaluated the option based on building 

ventilation as described in the 2011 proposal. This control 

option involves installation of full building ventilation at 

negative pressure for furnace buildings instead of installing 

fugitive controls on individual tapping and casting operations. 

This option would require installation of ductwork from the roof 

vents of furnace buildings, additional fans, structural repairs 

to buildings and a new fabric filter for each building. Both 

Eramet and Felman provided extensive comments and information

regarding implementation of building ventilation, including cost 

estimates based on their own engineering analyses. We thoroughly 

reviewed the comments and information provided by the companies 

along with information gathered from other sources, and then 
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revised our costs analyses accordingly for this supplemental 

proposal.

We estimate that the full building enclosure option would 

reduce PM emissions from the facilities by 252 tons per year 

(and total HAP emissions by 83 tons per year). The total 

estimated capital cost for these fugitive controls is $61 

million. Annualized capital cost and operational and maintenance 

costs are estimated at $19 million per year, which results in an

estimated cost per ton of metal HAP removed of $226,000 per ton. 

We also estimate that this option would achieve PM emission 

reductions of 252 tons, resulting in cost per ton of PM removed 

of $74,200 per ton and achieve PM2.5 emission reductions of 53

tons, resulting in a cost per ton of PM2.5 removal of $353,000 

per ton. The incremental cost effectiveness comparing the 

enhanced capture option to the building ventilation option is 

$501,000 per ton of PM removed, $2.4 million per ton of PM2.5

removed and $2.2 million per ton of HAP removed.

Based on these analyses, we conclude that the full-building 

enclosure option with negative pressure may not be feasible and 

would have significant economic impacts on the facilities

(including potential closure for one or more facilities).

However, we conclude that the enhanced local capture option is a 

feasible and cost-effective approach to achieve significant 
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reductions in fugitive HAP emissions and will achieve almost as

much reductions as the full-building enclosure option (229 vs 

252 tons PM reductions) thus achieving most of the risk 

reductions. In light of the technical feasibility and cost 

effectiveness of the enhanced capture options, we are proposing 

the enhanced capture option under the authority of section 

112(d)(6) of the CAA.

In the 2011 proposal, we included a requirement that 

emissions exiting from a shop building may not exceed more than 

10 percent opacity for more than one 6-minute period, to be 

demonstrated every 5 years as part of the periodic required 

performance tests. For day-to-day continuous monitoring to 

demonstrate compliance with the proposed shop building 

requirements, the 2011 proposal relied on achieving the 

requirement to maintain the shop building at negative pressure 

to at least 0.007 inches of water. This was to be supplemented 

by operation and work practice standards that required 

preparation of a process fugitive emissions ventilation plan for 

each shop building, which would include schematics with design 

parameters (e.g., air flow and static pressure) of the 

ventilation system. The source would conduct a baseline survey 

to verify that building air supply and exhaust are balanced and 

the building will be maintained under at least 0.007 inches of 
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water. Such plan would identify critical maintenance activities 

and schedules, be submitted to the permitting authority and 

incorporated into the source’s operating permit. The baseline 

survey would be repeated every 5 years or following significant 

changes to the ventilation system. 

With the move to the proposed enhanced local capture 

alternative, we believe that more frequent opacity monitoring 

based on an average of 8 percent opacity at all times, is 

appropriate to demonstrate compliance with the process fugitives 

standards. We propose that if the average opacity reading from 

the shop building is greater than 8 percent opacity during an 

observed furnace process cycle, an additional two more furnace 

process cycles must be observed such that the average opacity 

during the entire observation period is less than 7 percent 

opacity. A furnace process cycle means the period in which the 

furnace is tapped to the time in which the furnace is tapped 

again and includes periods of charging, smelting, tapping, 

casting and ladle raking. We also propose that at no time during 

operation may any two consecutive 6-minute block opacity 

readings be greater than 20 percent opacity. We believe that the 

longer averaging time for this new opacity limit (furnace 

process cycle vs. individual 6-minute averages) addresses 

concerns that small variations in an otherwise well-controlled 
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furnace cycle could result in violations of the opacity 

standard. The proposed 20 percent ceiling ensures that that 

there are no acute events that could adversely affect public 

health. Finally, the lower limit (8 vs. 10 percent opacity) also 

reflects that sources should achieve lower overall emissions 

over a longer averaging period. We propose that sources be 

required to conduct opacity observations at least once per week 

for each operating furnace and each MOR operation. Similar to 

the 2011 proposal, continuous monitoring of key ventilation 

operating system parameters and periodic inspections of the 

ventilation systems would ensure that the ventilation systems

are operating as designed. 

Also, similar to the 2011 proposal, we believe that the 

source should demonstrate that the overall design of the 

ventilation system is adequate to achieve the proposed 

standards. We propose that the facilities in this source

category must maintain a process fugitives capture system that 

is designed to collect 95 percent or more of the process 

fugitive emissions from furnace operations, casting MOR process, 

ladle raking and slag skimming and crushing and screening 

operations and convey the collected emissions to a control 

device that meets specified emission limits and the proposed 

opacity limits. We believe that if the source designs the plan 
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according to the most recent (at the time of construction) 

ventilation design principles recommended by the American 

Conference of Governmental Industrial Hygienists (ACHIH), 

includes detailed schematics of the ventilation system design, 

addresses variables that affect capture efficiency such as cross 

drafts and describes protocol or design characteristics to 

minimize such events and identifies monitoring and maintenance 

steps, the plan will be capable of ensuring the system is 

properly designed and continues to operate as designed. We would 

continue to require that this plan be submitted to the 

permitting authority, incorporated into the source’s operating 

permit and updated every 5 years or when there is a significant 

change in variables that affect process fugitive emissions

ventilation design. This list of design criteria, coupled with 

the requirement for frequent opacity observations and operating 

parameter monitoring will result in enforceable requirements. We 

recognize that other design requirements and/or more frequent 

opacity observations may yield more compliance certainty, but 

incur greater costs and not result in measurable decreases in 

emissions. However, we request comment on other measures that 

could be considered to demonstrate that well designed (e.g., at 

least 95 percent overall capture of process fugitive emissions) 

plans are developed and maintained. We request that such 
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comments include costs, measurement techniques or other 

information to evaluate their efficacy.

E. What other actions are we proposing?

In addition to the proposed actions described above, we reevaluated compliance requirements associated with the 2011 

proposed amendments to determine whether we should make changes 

to those proposed amendments. Based on this re-evaluation, we 

are proposing the following changes to what was proposed in the 

2011 proposal.

1. Stack Emission Limits 

In response to public comments, we revisited the format of 

the stack emission limits. We concluded that a concentrationbased limit is still appropriate, but we agree that the proposed 

CO2 concentration correction poses a problem under certain 

control device configurations. While such a concentration 

correction is appropriate for combustion sources such as 

boilers, we agree that its use in the context of ferroalloys 

production is not helpful. The PM stack limits proposed above do 

not include a CO2 correction.

2. Emissions Averaging

As described above, we have decided to retain a 

concentration format for the emissions limits for the stacks but 

we are not retaining the emissions averaging provision in this 
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supplemental proposal that we had proposed in 2011. We believe a 

concentration format is the best format for this NESHAP and we 

have concluded that it is not the best format to use under an 

emissions averaging option. We are concerned that emissions from 

a large furnace emitting a lower than average concentration 

could still emit more emissions than a small furnace with a 

higher than average concentration. This could result in a net 

increase in emissions from the two furnaces compared to their 

emissions if they were not allowed to average emissions. For 

this reason, we are proposing not to include the emissions 

averaging provisions in the rule, which is a change from the 

2011 proposal. 

3. Fenceline Monitoring Alternative

In the 2011 proposal, we assumed there could be control 

measures other than maintaining the furnace buildings under 

negative pressure that would achieve equivalent emissions 

reductions. Therefore, to provide some flexibility to facilities 

regarding how to achieve the reductions of fugitive emissions, 

in lieu of building the full enclosure and evacuation system 

described in the 2011 proposal, we proposed that sources could 

demonstrate compliance with an alternative approach by 

conducting fenceline monitoring and demonstrate that the ambient 

concentrations of manganese at their facility boundary remain at 
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levels no more than 0.1 μg/m3 on a 60-day rolling average. 

However, at this time, we believe that the proposed enhanced 

local capture option described in this supplemental proposal 

incorporates the features anticipated in a non-negative pressure 

building option and contains compliance requirements (based on 

meeting a tight opacity limit and other requirements) that would 

assess emissions at the point of the maximum output, that is, 

from the roof monitor of the ferroalloys production building. 

Furthermore, we determined there were various issues associated 

with fenceline monitoring at facilities within this source 

category, including highly variable wind patterns, uncertainties 

as to how to account for background concentrations and road dust

and the large difference between emissions release heights (from 

the high roof vents and stacks) compared to heights where 

fenceline monitors would be located (near ground level). 

Therefore, we are proposing to not include fenceline monitoring 

in the final rule as an alternative method to demonstrate 

compliance with a specific ambient level as was described in the 

2011 proposal. We believe the proposed tight opacity limit 

(which would be measured at the emissions sources), along with 

the proposed requirements to install, operate and maintain 

effective fugitive capture and control systems, emissions limits 

for the stacks and various parametric monitoring requirements, 
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are appropriate control requirements to ensure effective capture 

and control of emissions. However, as described in Section V.I. 

of this Notice, we are seeking comments regarding other possible 

options to monitor fugitive emissions, including fenceline 

monitoring as a tool to monitor trends in ambient concentrations 

at these locations and to use this information (along with 

meteorological data and modeling tools) to attempt to quantify 

trends in emissions that are leaving and entering the facility 

property.

4. Startup, Shutdown, Malfunction

In the 2011 proposal, we proposed to eliminate two 

provisions that exempt sources from the requirement to comply 

with the otherwise applicable CAA section 112(d) emission

standards during periods of SSM. We also included provisions for 

affirmative defense to civil penalties for violations of 

emission standards caused by malfunctions. Periods of startup, 

normal operations, and shutdown are all predictable and routine 

aspects of a source’s operations. 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). As explained 

in the 2011 proposal, the EPA interprets CAA section 112 as not 
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requiring emissions that occur during periods of malfunction to 

be factored into development of CAA section 112 standards. Under 

section 112, emissions standards for new sources must be no less 

stringent than the level “achieved” by the best controlled 

similar source and for existing sources generally must be no 

less stringent than the average emission limitation “achieved” 

by the best performing 12 percent of sources in the category. 

There is nothing in section 112 that directs the Agency to 

consider malfunctions in determining the level “achieved” by the 

best performing sources when setting emission standards. As the 

D.C. Circuit has recognized, the phrase “average emissions 

limitation achieved by the best performing 12 percent of” 

sources “says nothing about how the performance of the best 

units is to be calculated.” Nat'l Ass'n of Clean Water Agencies

v. EPA, 734 F.3d 1115, 1141 (D.C. Cir. 2013). While the EPA 

accounts for variability in setting emissions standards, nothing 

in section 112 requires the Agency to consider malfunctions as 

part of that analysis. A malfunction should not be treated in 

the same manner as the type of variation in performance that 

occurs during routine operations of a source. A malfunction is a 

failure of the source to perform in a “normal or usual manner” 

and no statutory language compels the EPA to consider such 

events in setting section 112 standards.
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Further, accounting for malfunctions in setting emission 

standards would be difficult, if not impossible, given the 

myriad different types of malfunctions that can occur across all 

sources in the category and given the difficulties associated 

with predicting or accounting for the frequency, degree and

duration of various malfunctions that might occur. As such, the 

performance of units that are malfunctioning is not “reasonably” 

foreseeable. See, e.g., Sierra Club v. EPA, 167 F.3d 658, 662 

(D.C. Cir. 1999) (“The EPA typically has wide latitude in 

determining the extent of data-gathering necessary to solve a 

problem. We generally defer to an agency's decision to proceed 

on the basis of imperfect scientific information, rather than to 

'invest the resources to conduct the perfect study.'") See also, 

Weyerhaeuser v. Costle, 590 F.2d 1011, 1058 (D.C. Cir. 1978) (“ 

In the nature of things, no general limit, individual permit, or 

even any upset provision can anticipate all upset situations. 

After a certain point, the transgression of regulatory limits 

caused by ‘uncontrollable acts of third parties,’ such as

strikes, sabotage, operator intoxication or insanity, and a 

variety of other eventualities, must be a matter for the 

administrative exercise of case-by-case enforcement discretion, 

not for specification in advance by regulation.”). In addition, 

emissions during a malfunction event can be significantly higher 
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than emissions at any other time of source operation. For 

example, if an air pollution control device with 99 percent 

removal goes off-line as a result of a malfunction (as might 

happen if, for example, the bags in a baghouse catch fire) and 

the emission unit is a steady state type unit that would take 

days to shut down, the source would go from 99 percent control 

to zero control until the control device was repaired. The 

source’s emissions during the malfunction would be 100 times 

higher than during normal operations. As such, the emissions 

over a 4-day malfunction period would exceed the annual 

emissions of the source during normal operations. As this 

example illustrates, accounting for malfunctions could lead to 

standards that are not reflective of (and significantly less 

stringent than) levels that are achieved by a well-performing 

non-malfunctioning source. It is reasonable to interpret section 

112 to avoid such a result. The EPA’s approach to malfunctions 

is consistent with section 112 and is a reasonable 

interpretation of the statute. 

 In the event that a source fails to comply with the 

applicable CAA section 112 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, 
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including preventative and corrective actions, as well as root 

cause analyses to ascertain and rectify excess emissions. The 

EPA would also consider whether the source's failure to comply 

with the CAA section 112 standard was, in fact, “sudden, 

infrequent, not reasonably preventable” and was not instead 

“caused in part by poor maintenance or careless operation.” 40 

CFR § 63.2 (definition of malfunction).

Further, to the extent the EPA files an enforcement action 

against a source for violation of an emission standard, the 

source can raise any and all defenses in that enforcement action 

and the federal district court will determine what, if any, 

relief is appropriate. The same is true for citizen enforcement 

actions. Similarly, the presiding officer in an administrative 

proceeding can consider any defense raised and determine whether 

administrative penalties are appropriate. 

As noted above, the 2011 proposal included an affirmative 

defense to civil penalties for violations caused by 

malfunctions. EPA included the affirmative defense in the 2011 

proposal as it had in several prior rules in an effort to create 

a system that incorporates some flexibility, recognizing that 

there is a tension, inherent in many types of air regulation, to 

ensure adequate compliance while simultaneously recognizing that 

despite the most diligent of efforts, emission standards may be 
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violated under circumstances entirely beyond the control of the 

source. Although the EPA recognized that its case-by-case 

enforcement discretion provides sufficient flexibility in these 

circumstances, it included the affirmative defense in the 2011 

proposal and in several prior rules to provide a more formalized 

approach and more regulatory clarity. See Weyerhaeuser Co. v. 

Costle, 590 F.2d 1011, 1057-58 (D.C. Cir. 1978) (holding that an 

informal case-by-case enforcement discretion approach is 

adequate); but see Marathon Oil Co. v. EPA, 564 F.2d 1253, 1272-

73 (9th Cir. 1977) (requiring a more formalized approach to 

consideration of “upsets beyond the control of the permit 

holder.”). Under the EPA’s regulatory affirmative defense 

provisions, if a source could demonstrate in a judicial or 

administrative proceeding that it had met the requirements of 

the affirmative defense in the regulation, civil penalties would 

not be assessed. The United States Court of Appeals for the 

District of Columbia Circuit vacated an affirmative defense in 

one of the EPA’s Section 112 regulations. NRDC v. EPA, 749 F.3d 

1055 No. 10-1371 (D.C. Cir., 2014) (vacating affirmative defense 

provisions in Section 112 rule establishing emission standards 

for Portland cement kilns). The court found that the EPA lacked 

authority to establish an affirmative defense for private civil 

suits and held that under the CAA, the authority to determine 
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civil penalty amounts in such cases lies exclusively with the 

courts, not the EPA. Specifically, the Court found: “As the 

language of the statute makes clear, the courts determine, on a 

case-by-case basis, whether civil penalties are ‘appropriate.’” 

See NRDC at *21 (“[U]nder this statute, deciding whether 

penalties are ‘appropriate’ in a given private civil suit is a 

job for the courts, not EPA.”). In light of NRDC, the EPA is 

withdrawing its proposal to include a regulatory affirmative 

defense provision in this rulemaking and in this proposal has 

eliminated sections 63.1627 and 63.1662 (the affirmative defense 

provisions in the proposed rule published in the Federal 

Register on November 23, 2011 (76 FR 72508)). As explained 

above, if a source is unable to comply with emissions standards 

as a result of a malfunction, the EPA may use its case-by-case 

enforcement discretion to provide flexibility, as appropriate. 

Further, as the D.C. Circuit recognized, in an EPA or citizen 

enforcement action, the court has the discretion to consider any 

defense raised and determine whether penalties are appropriate. 

Cf. NRDC at *24. (arguments that violation were caused by 

unavoidable technology failure can be made to the courts in 

future civil cases when the issue arises). The same logic 

applies to EPA administrative enforcement actions.

F. What compliance dates are we proposing?
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The proposed changes to the 2011 proposal that are set out 

in this supplementary proposal will not change the compliance 

dates proposed. We continue to propose that facilities must 

comply with the changes set out in this supplementary proposal

(which are being proposed under CAA sections 112(d)(2), 

112(d)(3), 112(d)(6) and 112(f)(2) for all affected sources), no 

later than 2 years after the effective date of the final rule. 

We find that 2 years are necessary to complete the installation 

of the enhanced local capture system and other controls. In the 

period between the effective date of this rule and the 

compliance date, existing sources would continue to comply with 

the existing requirements specified in §§63.1650 through 

63.1661, which will protect the health of persons from imminent 

endangerment. 

V. Summary of the Revised Cost, Environmental and Economic 

Impacts

A. What are the affected sources?

We maintain, as at the 2011 proposal, that the two 

manganese ferroalloys production facilities currently operating 

in the United States will be affected by these proposed 

amendments. We do not know of any new facilities that are 

expected to be constructed in the foreseeable future. However, 

there is one other facility that has a permit to produce 
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ferromanganese or silicomanganese in an electric arc furnace, 

but it is not doing so at present. It is possible, however, that 

this facility could resume production or another non-manganese 

ferroalloy producer could decide to commence production of 

ferromanganese or silicomanganese. Given this uncertainty, our 

impact analysis is focused on the two existing sources that are 

currently operating.

B. What are the air quality impacts?

The EPA revised the estimated emissions reductions that are 

expected to result from the proposed amendments to the 1999 

NESHAP based on the proposed changes in this supplemental 

proposal. A detailed documentation of the analysis can be found 

in the Cost Impacts document, which is available in the docket.

As noted in the 2011 proposal, emissions of metal HAP from 

ferroalloys production sources have declined in recent years, 

primarily as the result of state actions and also due to the 

industry’s own initiative. The proposed amendments in this

supplemental proposal would cut HAP emissions (primarily 

particulate metal HAP such as manganese, arsenic and nickel) by 

about 60 percent from their current levels. Under the revised 

proposed emissions standards for process fugitives emissions 

from the furnace building, we estimate that the HAP emissions 
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reductions would be 77 tpy, including significant reductions of 

manganese.

As noted in the 2011 proposal, based on the emissions data 

available to the EPA, we believe that both facilities will be 

able to comply with the proposed emissions limits for HCl 

without additional controls. Based on the analyses presented 

today, we also anticipate that both facilities will be able to 

comply with the proposed emission limits for mercury and PAH

without additional controls.

C. What are the cost impacts?

Under the revised proposed amendments, ferroalloys 

production facilities are expected to incur costs for the design 

of a local ventilation system, resulting in a site-specific 

local ventilation plan and installation of custom hoods and 

ventilation equipment and additional control devices to manage 

the air flows generated by the enhanced capture systems. There

would also be capital costs associated with installing new or 

improved continuous monitoring systems, including installation 

of BLDS on the furnace baghouses that are not currently equipped 

with these systems. 

The revised capital costs for each facility were estimated 

based on the projected number and types of upgrades required. 

The specific enhancements for each facility were selected for 
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cost estimation based on estimates directly provided by the 

facilities based on their engineering analyses and discussions

with the EPA. The Cost Impacts document includes a complete 

description of the revised cost estimate methods used for this 

analysis and is available in the docket.

Cost elements vary by plant and furnace and include the 

following elements:

 Curtains or doors surrounding furnace tops to contain 

fugitive emissions;

 Improvements to hoods collecting tapping emissions;

 Upgraded fans to improve the airflow of fabric filters 

controlling fugitive emissions;

 Addition of “secondary capture” or additional hoods to 

capture emissions from tapping platforms or crucibles;

 Addition of fugitives capture for casting operations;

 Improvement of existing control devices or addition of 

fabric filters; and

 Addition of rooftop ventilation, in which fugitive 

emissions escaping local control are collected in the 

roof canopy over process areas through addition of 

partitions and hoods, then directed through roof vents 

and ducts to control devices.
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For purposes of the supplemental proposal analysis, we 

assumed that enhanced fugitive capture and control systems and 

roofline ventilation will be installed for all operational

furnaces at both facilities and for MOR operations at Eramet 

Marietta. The specific elements of the capture and control 

systems selected for each facility are based on information 

supplied by the facilities incorporating their best estimates of 

the improvements to fugitive emission capture and control they 

would implement to achieve the standards included in the 

supplemental proposal. We estimate the total capital costs of 

installing the required ductwork, fans and control devices under 

the enhanced capture option to be $37.6 million and the total 

annualized cost to be $7.1 million (2012 dollars) for the two 

plants. We estimate that this option would reduce metal HAP 

emissions by 75 tons, resulting in a cost per ton of metal HAP 

removed to be $94,700 per ton ($47 per pound). The total HAP 

reduction for the enhanced capture option is estimated to be 77 

tons per year at a cost per ton of $91,900 per ton ($46 per 

pound). We also estimate that this option would achieve PM 

emission reductions of 229 tons per year, resulting in cost per 

ton of PM removed of $30,900 per ton and achieve PM2.5 emission 

reductions of 48 tons per year, resulting in a cost per ton of 

PM2.5 removal of $147,000 per ton. 
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D. What are the economic impacts?

As a result of the requirements in this supplemental 

proposal, we estimate that the total capital cost for the Eramet 

facility will be about $25 million and the total annualized 

costs will be about $5.4 million (in 2012 dollars). For impacts 

to Felman Production LLC, this facility is estimated to incur a 

total capital cost of $12.4 million and a total annualized costs 

of just under $1.7 million (in 2012 dollars). In total, these 

costs could lead to an increase in annualized cost of as much as 

1.8 percent of sales, which serves as an estimate for the 

increase in product prices, and a decrease in output of as much 

as 9.5 percent. For more information regarding economic impacts, 

please refer to the Economic Impact Analysis report that is 

included in the public docket for this supplemental proposal.

E. What are the benefits?

The estimated reductions in HAP emissions (i.e., about 77

tpy) that would be achieved by this proposal would provide 

significant benefits to public health. For example, there would 

be a significant reduction in emissions of air toxics 

(especially Mn, Ni, Cd and PAHs). In addition to the HAP 

reductions, we also estimate that this supplemental proposal 

would achieve about 48 tons of reductions in PM2.5 emissions as a 

co-benefit of the HAP reductions annually.
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This rulemaking is not an “economically significant 

regulatory action” under Executive Order 12866 because it is not 

likely to have an annual effect on the economy of $100 million 

or more. Therefore, we have not conducted a Regulatory Impact 

Analysis (RIA) for this rulemaking or a benefits analysis. While 

we expect that these avoided emissions will result in 

improvements in air quality and reduce health effects associated 

with exposure to air pollution associated with these emissions, 

we have not quantified or monetized the benefits of reducing 

these emissions for this rulemaking. This does not imply that 

there are no benefits associated with these emission reductions. 

When determining if the benefits of an action exceed its costs, 

Executive Orders 12866 and 13563 direct the Agency to consider 

qualitative benefits that are difficult to quantity but 

nevertheless essential to consider. 

Directly emitted particles are precursors to secondary 

formation of fine particles (PM2.5). Controls installed to reduce 

HAP would also reduce ambient concentrations of PM2.5 as a cobenefit. Reducing exposure to PM2.5 is associated with significant 

human health benefits, including avoiding mortality and 

morbidity from cardiovascular and respiratory illnesses. 

Researchers have associated PM2.5 exposure with adverse health 

effects in numerous toxicological, clinical and epidemiological 
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studies (U.S. EPA, 2009)58. When adequate data and resources are 

available and an RIA is required, the EPA generally quantifies 

several health effects associated with exposure to PM2.5 (e.g., 

U.S. EPA, 2012)59. These health effects include premature 

mortality for adults and infants, cardiovascular morbidities 

such as heart attacks, hospital admissions and respiratory 

morbidities such as asthma attacks, acute bronchitis, hospital 

and emergency department visits, work loss days, restricted 

activity days and respiratory symptoms. The scientific 

literature also suggests that exposure to PM2.5 is also associated 

with adverse effects on birth weight, pre-term births, pulmonary 

function and other cardiovascular and respiratory effects (U.S. 

EPA, 2009), but the EPA has not quantified certain outcomes 

these impacts in its benefits analyses. PM2.5 also increases light 

extinction, which is an important aspect of visibility.

The rulemaking is also anticipated to reduce emissions of 

other HAP, including metal HAP (arsenic, cadmium, chromium (both 

total and Cr+6), lead compounds, manganese and nickel) and PAHs. 

 

58 U.S. Environmental Protection Agency (U.S. EPA). 2009. Integrated Science 

Assessment for Particulate Matter (Final Report). EPA-600-R-08-139F. 

National Center for Environmental Assessment—RTP Division. Available on the 

Internet at http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=216546. 

59 U.S. Environmental Protection Agency (U.S. EPA). 2012. Regulatory Impact

Analysis for the Proposed Revisions to the National Ambient Air Quality 

Standards for Particulate Matter. Office of Air and Radiation, Research 

Triangle Park, NC. Available on the Internet at 

http://www.epa.gov/ttnecas1/regdata/RIAs/PMRIACombinedFile_Bookmarked.pdf. 
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Some of these HAP are carcinogenic (e.g., arsenic, PAHs) and 

some have effects other than cancer (e.g., kidney disease from 

cadmium, respiratory and immunological effects from nickel). 

While we cannot quantitatively estimate the benefits achieved by 

reducing emissions of these HAP, we would expect benefits by 

reducing exposures to these HAP. More information about the 

health effects of these HAP can be found on the IRIS,60 ATSDR,61

and California EPA62 webpages.

VI. Request for Comments

We solicit comments on the revised risk assessment and 

technology review and proposed changes to the previously

proposed amendments. We seek comments on the additional data 

received in August 2014 (as described in Section II.D above) and 

the impacts of those new data on the analyses and results 

presented in this notice. We seek comments on the sufficiency of 

the proposed controls for process fugitive emissions, the design 

of such systems and how best to monitor them to ensure the 

systems achieve the estimated efficiency. We also seek comments 

 

60 US EPA, 2006. Integrated Risk Information System. 

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

61 US Agency for Toxic Substances and Disease Registry, 2006. Minimum Risk 

Levels (MRLs) for Hazardous Substances. 

http://www.atsdr.cdc.gov/mrls/index.html.

62 CA Office of Environmental Health Hazard Assessment, 2005. Chronic 

Reference Exposure Levels Adopted by OEHHA as of December 2008. 

http://www.oehha.ca.gov/air/chronic_rels.
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on other aspects of this supplemental proposal, including, but 

not limited to, the proposed opacity standards.

The EPA is also soliciting comment with regard to expanding 

the monitoring requirements in this NESHAP for fugitive 

particulate matter and manganese emissions being released at the 

roof vents of furnace buildings using one or more of three 

different options. For the following three options the EPA is 

additionally seeking comment on the frequency of monitoring and 

the cost associated with installation, operation, analysis and 

ongoing reporting. Additional cost information of these three 

monitoring options is included in the Cost Impacts document, 

which is available in the docket.

First, the EPA is soliciting comment on the potential to 

require the facilities to take periodic measurements of fugitive 

particulate matter and manganese emissions from the roof vents 

using portable filter based measurement technologies. The EPA 

solicits comment on requiring no less than 3 filter based 

monitoring systems with associated anemometers with the goal of 

quantifying trends in the process fugitive emissions that are 

leaving the furnace buildings. We also solicit comment on the 

appropriate sampling duration and frequency of such measurements 

(e.g., 8-hour samples gathered at each monitor several times per 

week or month). This monitoring could provide useful information 
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regarding the remaining fugitive emissions that will be escaping 

the buildings after the facilities install and operate the 

improved capture and controls systems that we expect will be 

installed to comply with this proposed rule. This information 

will also help improve our understanding of the relationship 

between the process fugitive emissions and the specific 

operations within the furnace buildings. However, the 

measurements would not be tied to a specific emissions limit.

Second, the EPA is soliciting comment on requiring fugitive 

fenceline filter based measurements of particulate matter and 

manganese emissions at the facilities with no less than 3 

monitoring systems at the property boundaries to monitor trends 

in ambient concentrations at these locations and to use this 

information (along with meteorological data and modeling tools) 

to attempt to quantify trends in emissions that are leaving and 

entering the facility property. The EPA seeks comment on having 

the monitoring systems use common ambient filter based sampling 

techniques as well as gathering data on meteorological 

conditions simultaneously at each of the sampling sites. The EPA 

recognizes that this monitoring would be capturing both ground 

level and other fugitive emissions from the facilities as well 

as background contributions from other sources, and that this 

type of monitoring has limitations. Nevertheless, EPA is taking 
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comment on the application and appropriateness of this type of 

monitoring as part of the requirements within this NESHAP to 

evaluate emissions leaving the facility property and is taking 

comment on where to position the monitoring systems to best 

evaluate the fugitive emissions. 

Third, the EPA is soliciting comment regarding the use of 

new technologies to provide continuous or near continuous long 

term approaches to monitoring emissions from industrial sources 

such the Ferroalloys production facilities within this source 

category. To this end we are seeking comment on the feasibility 

and practice associated with the use of automated Opacity 

Monitoring with ASTM D7520-13, using digital camera technology 

(DCOT) at fixed points to interpret visible emissions from roof 

vents associated with the processes at each facility, and how 

this technology could potentially be included as part of the 

requirements in the NESHAP for ferroalloys production sources. 

Specifically we are interested in comments regarding how many 

fixed camera locations would be needed to provide sufficient 

sun-angle viewing during daylight operating hours, and the 

frequency of the EXIF 2.1 JPG image analysis (how often the roof 

vent plume should be evaluated).

The EPA is moving toward advances in information and 

emissions monitoring technology that is setting the stage for 
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detection, processing and communication capabilities that can 

revolutionize environmental protection. The EPA calls this Next 

Generation Compliance. One of the advances in information 

sharing is increased transparency. Using transparency as a way 

to improve performance and increase compliance, the EPA is 

seeking comments on whether affected sources should be required 

to post Method 9 readings on their company web sites and/or 

State dashboards.

Electronic reporting is another next generation tool that 

saves time and money while improving results. The EPA is asking 

for comments on whether the EPA should require affected sources 

to submit all compliance documents such as notice of compliance 

status form, deviations from the process fugitive ventilation 

plan and outdoor fugitive dust plan, and electronic records of 

the bag leak detection system output.

We are not opening comment on aspects of the 2011 proposal 

(76 FR 72508) that have not changed and are not addressed in 

this supplemental proposal. Comments received on the 2011 

proposal along with comments received on this supplemental 

proposal will be addressed in the EPA’s Response to Comment 

document and final rule preamble for the Ferroalloys Production 

source category.

VII. Submitting Data Corrections
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The site-specific emissions profiles used in the source 

category risk and demographic analyses and instructions 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 facilities in the source category.

If you believe that the data are not representative or are 

inaccurate, please identify the data in question, provide your 

reason for concern and provide any “improved” data that you 

have, if available. When you submit data, we request that you 

provide documentation of the basis for the revised values to 

support your suggested changes. To submit comments on the data 

downloaded from the RTR page, complete the following steps:

1. Within this downloaded file, enter suggested revisions 

to the data fields appropriate for that information.

2. Fill in the commenter information fields for each 

suggested revision (i.e., commenter name, commenter 

organization, commenter email address, commenter phone number 

and revision comments).

3. Gather documentation for any suggested emissions 

revisions (e.g., performance test reports, material balance 

calculations, etc.).
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4. Send the entire downloaded file with suggested revisions 

in Microsoft® Access format and all accompanying documentation 

to Docket ID Number EPA-HQ-OAR-*** (through one of the methods 

described in the ADDRESSES section of this preamble).

5. If you are providing comments on a single facility or 

multiple facilities, you need only submit one file for all 

facilities. The file should contain all suggested changes for 

all sources at that facility. We request that all data revision 

comments be submitted in the form of updated Microsoft® Excel 

files that are generated by the Microsoft® Access file. These 

files are provided on the RTR Web Page at: 

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

VIII. Statutory and Executive Order Reviews

A. Executive Order 12866: Regulatory Planning and Review and 

Executive Order 13563: Improving Regulation and Regulatory 

Review

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 
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recommendations have been documented in the docket for this 

action.

B. Paperwork Reduction Act

The information collection requirements in this 

supplemental proposed 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 EPA ICR number 2448.01.

We are proposing changes to the paperwork requirements to 

the ferroalloys production source category that were proposed in 

2011. In the 2011 proposal, we proposed paperwork requirements 

in the form of increased frequency and number of pollutants 

tested for stack testing as described in §63.1625(c) and tighter 

parameter monitoring requirements to demonstrate continuous 

compliance as described in §63.1625(c)(4) and §63.1626. We are 

not proposing changes to these requirements. However, in this 

supplemental proposal we are proposing more frequent opacity 

monitoring requirements compared to the 2011 proposal and are 

removing the shop building process fugitives monitoring

requirements (to demonstrate negative pressure) that we proposed 

in 2011. 
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In addition, in the 2011 proposal, we included an estimate 

of the burden associated with the affirmative defense in the 

ICR. However, as explained above, in this supplemental proposal

we are withdrawing our proposal to include an affirmative 

defense and the burden estimate has been revised accordingly.

We estimate two regulated entities are currently subject to 

subpart XXX and will be subject to this action. The annual 

monitoring, reporting and recordkeeping burden for this 

collection (averaged over the first 3 years after the effective 

date of the standards) as a result of the supplemental proposal 

revised amendments to subpart XXX (Ferroalloys Production) is 

estimated to be $643,845 per year. This includes 496 labor hours 

per year at a total labor cost of $44,366 per year and total 

non-labor capital and operation and maintenance costs, of 

$599,479 per year. This estimate includes performance tests, 

notifications, reporting and recordkeeping associated with the 

new requirements for ferroalloys production operations. The 

total burden for the federal government (averaged over the first 

3 years after the effective date of the standard) is estimated 

to be 48 hours per year at a total labor cost of $2,177 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 
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displays a currently valid OMB control number. The OMB control 

numbers for the EPA's regulations in 40 CFR are listed in 40 CFR 

part 9.

To comment on the Agency's need for this information, the 

accuracy of the provided burden estimates and any suggested 

methods for minimizing respondent burden, the EPA has 

established a public docket for this rule, which includes this 

ICR, under Docket ID number Docket ID Number EPA-HQ-OAR-2010-

0895. Submit any comments related to the ICR to the EPA and 

OMB. See 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 [Insert date of publication in the Federal Register.], a 

comment to OMB is best assured of having its full effect if OMB 

receives it by [Insert date 30 days after publication in the 

Federal Register]. The final rule will respond to any OMB or 

public comments on the information collection requirements 

contained in this proposal.

C. Regulatory Flexibility Act
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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 final 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 331110 (i.e., Electrometallurgical ferroalloy 

product manufacturing), the SBA small business size standard is 

1,000 employees according to the SBA small business standards 

definitions. 

After considering the economic impacts of today’s action on 

small entities, I certify that this action will not have a 
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significant economic impact on a substantial number of small 

entities. Neither of the companies affected by this rule is 

considered to be a small entity per the definition provided in 

this section. 

D. Unfunded Mandates Reform Act

This action does not contain a federal mandate under the 

provisions of Title II of the Unfunded Mandates Reform Act of 

1995 (UMRA), 2 U.S.C. 1531-1538 for state, local, or tribal 

governments, or the private sector. The action would not result 

in expenditures of $100 million or more for state, local and

tribal governments, in aggregate, or the private sector in any 1 

year. This final action imposes no enforceable duties on any 

state, local, or tribal governments, or the private sector. 

Thus, this action is not subject to the requirements of sections 

202 or 205 of the UMRA.

This 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 as it contains no requirements that apply to such 

governments nor does it impose obligations upon them.

E. Executive Order 13132: Federalism

This action does not have federalism implications. It will 

not have substantial direct effects on the states, on the 
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relationship between the national government and the states, or 

on the distribution of power and responsibilities among the 

various levels of government, as specified in Executive Order 

13132. None of the facilities subject to this action are owned 

or operated by state governments and, because no new 

requirements are being promulgated, nothing in this action will 

supersede state regulations. Thus, Executive Order 13132 does 

not apply to this action. 

F. Executive Order 13175: Consultation and Coordination with 

Indian Tribal Governments

This action does not have tribal implications, as specified 

in Executive Order 13175 (65 FR 67249, November 9, 2000). Thus, 

Executive Order 13175 does not apply to this action. The EPA 

specifically solicited comment on this action from tribal 

officials in the 2011 proposal and none were received during the 

comment period for that proposal.

G. Executive Order 13045: Protection of Children from 

Environmental Health Risks and Safety Risks

This action is not subject to Executive Order 13045 (62 FR 

19885, April 23, 1997) because the Agency does not believe the 

environmental health risks or safety risks addressed by this 

action present a disproportionate risk to children. The report, 

Analysis of Socio-Economic Factors for Populations Living Near 
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Ferroalloys Facilities, shows that, prior to the implementation 

of the provisions included in the proposal and this supplemental 

proposal, on a nationwide basis, there are approximately 31,000

people exposed to a cancer risk at or above 1-in-1 million and 

approximately 1,500 people exposed to a chronic noncancer TOSHI 

greater than 1 due to emissions from the source category. The 

percentages for all demographic groups, including children 18 

years and younger, are similar to or lower than their respective 

nationwide percentages. Further, implementation of the 

provisions included in this action is expected to significantly 

reduce the number of at-risk people due to HAP emissions from 

these sources (from up to 31,000 to about 6,600), providing 

significant benefit to all the demographic groups in the at-risk 

population.

This rule is expected to reduce environmental impacts for 

everyone, including children. This action establishes emissions 

limits at the levels based on MACT, as required by the CAA. 

Based on our analysis, we believe that this rule does not have a 

disproportionate impact on children. 

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, because it is not likely to have a 
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significant adverse effect on the supply, distribution or use of 

energy. This action will not create any new requirements that 

affect 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 No. 104-113, 12(d) 

(15 U.S.C. 272 note) directs the EPA to use voluntary consensus 

standards (VCS) in its regulatory activities, unless to do so 

would be inconsistent with applicable law or otherwise 

impractical. VCS are technical standards (e.g., materials 

specifications, test methods, sampling procedures and business 

practices) that are developed or adopted by VCS bodies. The 

NTTAA directs the EPA to provide Congress, through OMB, 

explanations when the agency decides not to use available and 

applicable VCS. 

This supplemental proposal involves technical standards. 

The EPA has decided to use EPA Methods 1, 2, 3A, 3B, 4, 5, 5D, 

9, 10, 26A, 29, 30B, 316, CARB 429, SW-846 Method 3052, SW-846 

Method 7471b and EPA water Method 1631E of 40 CFR Part 60, 

Appendix A. No applicable VCS were identified for EPA Methods 

30B, 5D, 316, 1631E and CARB 429, SW-846 Method 3052 and SW-846 

Method 7471b.

Two VCS were identified acceptable alternatives to the EPA 
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test methods for the purposes of this rule. The VCS standard 

ANSI/ASME PTC 19-10-1981-Part 10, “Flue and Exhaust Gas 

Analyses” is an acceptable alternative to Method 3B. The VCS 

ASTM D7520-09, “Standard Test Method for Determining the Opacity 

of a Plume in the Outdoor Ambient Atmosphere” is an acceptable 

alternative to Method 9 under specified conditions. The Agency 

identified 18 VCS as being potentially applicable to these 

methods cited in this rule. However, the EPA determined that the 

18 candidate VCS would not be practical due to lack of 

equivalency, documentation, validation data and other important 

technical and policy considerations. The 18 VCS and other 

information and conclusions, including the search and review 

results, are in the docket for this rule. 

Under §§63.7(f) and 63.8(f) of Subpart A of the General 

Provisions, a source may apply to the EPA for permission to use 

alternative test methods or alternative monitoring requirements 

in place of any required testing methods, performance 

specifications, or procedures in the proposed rule.

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. 
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Its main provision directs federal agencies, to the greatest 

extent practicable and permitted by law, to make environmental 

justice part of their mission by identifying and addressing, as 

appropriate, disproportionately high and adverse human health or 

environmental effects of their programs, policies and activities 

on minority populations and low-income populations in the United 

States. 

The EPA has determined that the current health risks posed 

by emissions from this source category are unacceptable. There 

are up to 31,000 people nationwide that are currently subject to 

health risks which may not be considered negligible (i.e., 

cancer risks greater than 1-in-1 million or chronic noncancer 

TOSHI greater than 1) due to emissions from this source 

category. The demographic makeup of this “at-risk” population is 

similar to the national distribution for all demographic groups. 

The proposed supplemental requirements along with other proposed 

requirements (76 FR 72508) will reduce the number of people in 

this at-risk group, from up to 31,000, to about 6,600 people. 

Based on this analysis, the EPA has determined that the proposed 

supplemental requirements will not have disproportionately high 

and adverse human health or environmental effects on minority or 

low-income populations because it increases the level of 

environmental protection for all affected populations. 
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National Emission Standards for Hazardous Air Pollutants: 

Ferroalloys Production

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List of Subjects in 40 CFR Part 63

Air pollution control, Environmental protection, Hazardous 

substances, Incorporation by reference, Reporting and 

recordkeeping requirements.

________________________.

Dated: 

________________________

Gina McCarthy,

Administrator.
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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.

2. Section 63.14 is amended by:

a. Adding paragraph (b)(84);

b. Revising paragraph (i)(1);

c. Revising paragraph (p)(6) and adding paragraphs (p)(21) 

and (p)(22); and

d. By adding paragraph (s). 

§63.14 Incorporations by reference.

(b) * * *

(84) ASTM D7520-09, “Standard Test Method for Determining 

the Opacity in a Plume in an Outdoor Ambient Atmosphere,” IBR 

approved for §§63.1625(b) and 63.1657(b).

* * * * *

(i) * * *

(1) ANSI/ASME PTC 19.10–1981, Flue and Exhaust Gas Analyses 

[Part 10, Instruments and Apparatus], issued August 31, 1981 IBR 

approved for §§63.309(k), 63. 772(e), 63.772(h), 63.865(b), 
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63.1282(d) and (g), 63.1625(b), 63.3166(a), 63.3360(e), 

63.3545(a), 63.3555(a), 63.4166(a), 63.4362(a), 63.4766(a), 

63.4965(a), 63.5160(d), 63.9307(c), 63.9323(a), 63.11148(e), 

63.11155(e), 63.11162(f), 63.11163(g), 63.11410(j), 63.11551(a), 

63.11646(a), 63.11945, table 5 to subpart DDDDD of this part, 

table 4 to subpart JJJJJ of this part, Table 5 of subpart UUUUU 

of this part and table 1 to subpart ZZZZZ of this part.

* * *

(p) * * *

(6) SW–846–7471B, Mercury in Solid Or Semisolid Waste 

(Manual Cold-Vapor Technique), Revision 2, February 2007, in EPA 

Publication No. SW–846, Test Methods for Evaluating Solid Waste, 

Physical/Chemical Methods, Third Edition, IBR approved for 

§63.1625(b), table 6 to subpart DDDDD of this part and table 5 

to subpart JJJJJJ of this part.

* * * * *

(21) SW-846-Method 3052, Microwave Assisted Acid Digestion 

Of Siliceous and Organically Based Matrices, Revision 0, 

December 1996, in EPA Publication No. SW–846, Test Methods for 

Evaluating Solid Waste, Physical/Chemical Methods, Third 

Edition, IBR approved for §63.1625(b).

(22) Method 1631, Revision E: Mercury in Water by 

Oxidation, Purge and Trap and Cold Vapor Atomic Fluorescence 
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Spectrometry, August 2002 located at: 

http://water.epa.gov/scitech/methods/cwa/metals/mercury/upload/2

007_07_10_methods_method_mercury_1631.pdf, IBR approved for 

§63.1625(b).

* * * * *

(s) The following material is available from the California 

Air Resources Board (CARB), 1102 Q Street, Sacramento, 

California 95814, (http://www.arb.ca.gov/testmeth/).

(1) Method 429, Determination of Polycyclic Aromatic 

Hydrocarbon (PAH) Emissions from Stationary Sources, Adopted 

September 1989, Amended July 1997, IBR approved for §63.1625(b).

(2) [Reserved]

* * * * *

Subpart XXX—[AMENDED]

3. Section 63.1620 is added to read as follows:

§63.1620 Am I subject to this subpart?

(a) You are subject to this subpart if you own or operate a 

new or existing ferromanganese and/or silicomanganese production 

facility that is a major source or is co-located at a major 

source of hazardous air pollutant emissions.

(b) You are subject to this subpart if you own or operate 

any of the following equipment as part of a ferromanganese or 

silicomanganese production facility:
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(1) Open, semi-sealed, or sealed submerged arc furnace,

(2) Casting operations,

(3) Metal oxygen refining (MOR) process,

(4) Crushing and screening operations,

(5) Outdoor fugitive dust sources.

(c) A new affected source is any of the sources listed in 

paragraph (b) of this section for which construction or 

reconstruction commenced after [INSERT DATE OF PUBLICATION IN 

THE FEDERAL REGISTER].

(d) Table 1 of this subpart specifies the provisions of 

subpart A of this part that apply to owners and operators of 

ferromanganese and silicomanganese production facilities subject 

to this subpart.

(e) If you are subject to the provisions of this subpart, 

you are also subject to title V permitting requirements under 40 

CFR parts 70 or 71, as applicable.

(f) Emission standards in this subpart apply at all times.

4. Section 63.1621 is added to read as follows:

§63.1621 What are my compliance dates?

(a) Existing affected sources must be in compliance with 

the provisions specified in §§63.1620 through 63.1629 no later 

than [INSERT DATE OF 2 YEARS AFTER EFFECTIVE DATE OF FINAL 

RULE].
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(b) Affected sources in existence prior to [INSERT DATE OF 

PUBLICATION IN THE FEDERAL REGISTER] must be in compliance with 

the provisions specified in §§63.1650 through 63.1661 by 

November 21, 2001 and until [INSERT DATE OF 2 YEARS AFTER 

EFFECTIVE DATE OF FINAL RULE AMENDMENTS]. As of [INSERT DATE OF 

2 YEARS AFTER EFFECTIVE DATE OF FINAL RULE AMENDMENTS], the 

provisions of §§63.1650 through 63.1661 cease to apply to 

affected sources in existence prior to [INSERT DATE OF 

PUBLICATION IN THE FEDERAL REGISTER]. The provisions of 

§§63.1650 through 63.1661 remain enforceable at a source for its 

activities prior to [INSERT DATE OF 2 YEARS AFTER EFFECTIVE DATE 

OF FINAL RULE AMENDMENTS].

(c) If you own or operate a new affected source that 

commences construction or reconstruction after [INSERT DATE OF 

PUBLICATION IN THE FEDERAL REGISTER], you must comply with the 

requirements of this subpart by [INSERT DATE OF EFFECTIVE DATE 

OF FINAL RULE AMENDMENTS], or upon startup of operations, 

whichever is later.

5. Section 63.1622 is added to read as follows:

§63.1622 What definitions apply to this subpart?

Terms in this subpart are defined in the Clean Air Act 

(Act), in subpart A of this part, or in this section as follows:

Bag leak detection system means a system that is capable of 
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continuously monitoring particulate matter (dust) loadings in 

the exhaust of a baghouse in order to detect bag leaks and other 

upset conditions. A bag leak detection system includes, but is 

not limited to, an instrument that operates on triboelectric, 

light scattering, light transmittance, or other effect to 

continuously monitor relative particulate matter loadings.

Capture system means the collection of components used to 

capture the gases and fumes released from one or more emissions 

points and then convey the captured gas stream to a control 

device or to the atmosphere. A capture system may include, but 

is not limited to, the following components as applicable to a 

given capture system design: duct intake devices, hoods,

enclosures, ductwork, dampers, manifolds, plenums, fans and 

roofline ventilation systems.

Casting means the period of time from when molten 

ferroalloy is removed from the tapping station until pouring 

into casting molds or beds is completed. This includes the 

following operations: pouring alloy from one ladle to another, 

slag separation, slag removal and ladle transfer by crane, 

truck, or other conveyance.

Crushing and screening equipment means the crushers, 

grinders, mills, screens and conveying systems used to crush, 

size and prepare for packing manganese-containing materials, 
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including raw materials, intermediate products and final 

products.

Electric arc furnace means any furnace where electrical 

energy is converted to heat energy by transmission of current 

between electrodes partially submerged in the furnace charge.

Furnace process cycle means the period in which the furnace 

is tapped to the time in which the furnace is tapped again and

includes periods of charging, smelting, tapping, casting and 

ladle raking. For multiple furnaces operating within a single 

shop building, furnace process cycle means a period sufficient 

to capture a full cycle of charging, smelting, tapping, casting 

and ladle raking for each furnace within the shop building.

Ladle treatment means a post-tapping process including 

metal and alloy additions where chemistry adjustments are made 

in the ladle after furnace smelting to achieve a specified 

product.

Local ventilation means hoods and ductwork designed to 

capture process fugitive emissions close to the area where the 

emissions are generated (e.g., tap hoods).

Metal oxygen refining (MOR) process means the reduction of 

the carbon content of ferromanganese through the use of oxygen.

Outdoor fugitive dust source means a stationary source from 

which hazardous air pollutant-bearing particles are discharged 
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to the atmosphere due to wind or mechanical inducement such as 

vehicle traffic. Fugitive dust sources include plant roadways, 

yard areas and outdoor material storage and transfer operations.

Plant roadway means any area at a ferromanganese and 

silicomanganese production facility that is subject to plant 

mobile equipment, such as forklifts, front end loaders, or 

trucks, carrying manganese-bearing materials. Excluded from this 

definition are employee and visitor parking areas, provided they 

are not subject to traffic by plant mobile equipment.

Process fugitive emissions source means a source of 

hazardous air pollutant emissions that is associated with a 

ferromanganese or silicomanganese production facility and is not 

a fugitive dust source. Process fugitive sources include 

emissions that escape capture from the electric arc furnace, 

tapping operations, casting operations, ladle treatment, MOR or 

crushing and screening equipment.

Roofline ventilation system means an exhaust system 

designed to evacuate process fugitive emissions that collect in 

the roofline area to a control device.

Shop building means the building which houses one or more 

electric arc furnaces or other processes that generate process 

fugitive emissions.

Shutdown means the cessation of operation of an affected 
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source for any purpose.

Startup means the setting in operation of an affected 

source for any purpose.

Tapping emissions means the gases and emissions associated 

with removal of product from the electric arc furnace under 

normal operating conditions, such as removal of metal under 

normal pressure and movement by gravity down the spout into the 

ladle and filling the ladle.

Tapping period means the time from when a tap hole is 

opened until the time a tap hole is closed.

6. Section 63.1623 is added to read as follows:

§63.1623 What are the emissions standards for new, reconstructed 

and existing facilities?

(a) Electric arc furnaces. You must install, operate and

maintain an effective capture system that collects the emissions 

from each electric arc furnace operation (including charging, 

melting and tapping operations and emissions from any vent 

stacks) and conveys the collected emissions to a control device 

for the removal of the pollutants specified in the emissions 

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

section.

(1) Particulate matter emissions. 

(i) You must not discharge exhaust gases from each electric 
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arc furnace operation containing particulate matter in excess of 

4.0 milligrams per dry standard cubic meter (mg/dscm) into the 

atmosphere from any new or reconstructed electric arc furnace. 

(ii) You must not discharge exhaust gases from each 

electric arc furnace operation containing particulate matter in 

excess of 25 mg/dscm into the atmosphere from any existing 

electric arc furnace. 

(2) Mercury emissions. 

(i) You must not discharge exhaust gases from each electric 

arc furnace operation containing mercury emissions in excess of 

17 μg/dscm into the atmosphere from any new or reconstructed 

electric arc furnace when producing ferromanganese.

(ii) You must not discharge exhaust gases from each 

electric arc furnace operation containing mercury emissions in 

excess of 170 μg/dscm into the atmosphere from any existing 

electric arc furnace when producing ferromanganese.

(iii) You must not discharge exhaust gases from each 

electric arc furnace operation containing mercury emissions in 

excess of 4.0 μg/dscm into the atmosphere from any new or 

reconstructed electric arc furnace when producing 

silicomanganese.

(iv) You must not discharge exhaust gases from each 

electric arc furnace operation containing mercury emissions in 
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excess of 12 μg/dscm into the atmosphere from any existing 

electric arc furnace when producing silicomanganese.

(3) Polycyclic aromatic hydrocarbon emissions. 

(i) You must not discharge exhaust gases from each electric 

arc furnace operation containing polycyclic aromatic hydrocarbon 

emissions in excess of 1,400 μg/dscm into the atmosphere from 

any existing electric arc furnace when producing ferromanganese. 

(ii) You must not discharge exhaust gases from each 

electric arc furnace operation containing polycyclic aromatic 

hydrocarbon emissions in excess of 880 μg/dscm into the 

atmosphere from any new or reconstructed electric arc furnace 

when producing ferromanganese.

(iii) You must not discharge exhaust gases from each 

electric arc furnace operation containing polycyclic aromatic 

hydrocarbon emissions in excess of 120 μg/dscm into the 

atmosphere from any existing electric arc furnace when producing 

silicomanganese.

(iv) You must not discharge exhaust gases from each 

electric arc furnace operation containing polycyclic aromatic 

hydrocarbon emissions in excess of 72 μg/dscm into the 

atmosphere from any new or reconstructed electric arc furnace 

when producing silicomanganese.

(4) Hydrochloric acid emissions. 
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(i) You must not discharge exhaust gases from each electric 

arc furnace operation containing hydrochloric acid emissions in 

excess of 180 μg/dscm into the atmosphere from any new or 

reconstructed electric arc furnace.

(ii) You must not discharge exhaust gases from each 

electric arc furnace operation containing hydrochloric acid 

emissions in excess of 1,100 μg/dscm into the atmosphere from 

any existing electric arc furnace.

(5) Formaldehyde emissions. You must not discharge exhaust 

gases from each electric arc furnace operation containing 

formaldehyde emissions in excess of 201 μg/dscm into the 

atmosphere from any new, reconstructed or existing electric arc 

furnace.

(b) Process fugitive emissions. 

(1) You must install, operate and maintain a capture system 

that is designed to collect 95 percent or more of the emissions 

from the process fugitive emissions sources and convey the 

collected emissions to a control device that is demonstrated to 

meet the applicable emission limit specified in paragraph (a)(1) 

of this section.

(2) The determination of 95-percent overall capture must be 

demonstrated as required by §63.1624(a).

(3) You must not cause the emissions exiting from a shop 
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building, to exceed an average of 8 percent opacity.

(i) The opacity readings from the shop building must be 

taken every 15 seconds during the observed furnace process cycle 

and the 15 second readings averaged to determine if the 8

percent opacity requirement has been met. 

(ii) If the average opacity reading from the shop building 

is greater than 8 percent opacity during an observed furnace 

process cycle, an additional two more furnace process cycles 

must be observed within 7 days and the average opacity during 

the entire observation periods must be less than 8 percent 

opacity.

(iii) At no time during operation may the average of any

two consecutive 6-minute blocks be greater than 20 percent 

opacity.

(c) Local ventilation emissions. If you operate local 

ventilation to capture tapping, casting, or ladle treatment 

emissions and direct them to a control device other than one 

associated with the electric arc furnace, you must not discharge 

into the atmosphere any captured emissions containing 

particulate matter in excess of 4.0 mg/dscm.

(d) MOR process. You must not discharge into the atmosphere 

from any new, reconstructed or existing MOR process exhaust 

gases containing particulate matter in excess of 3.9 mg/dscm.
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(e) Crushing and screening equipment. You must not 

discharge into the atmosphere from any new, reconstructed, or 

existing piece of equipment associated with crushing and 

screening exhaust gases containing particulate matter in excess 

of 13 mg/dscm.

(f) At all times, you 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 that 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 63.1624 is added to read as follows:

§63.1624 What are the operational and work practice standards 

for new, reconstructed and existing facilities?

(a) Process fugitive emissions sources.

(1) You must prepare and at all times operate according to, 

a process fugitive emissions ventilation plan that documents the 

design and operations to achieve at least 95 percent overall 

capture of process fugitive emissions. The plan will be deemed 
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to achieve this level of capture if it consists of the following 

elements:

(i) Documentation of engineered hoods and secondary 

fugitive capture systems designed according to the most recent, 

at the time of construction, ventilation design principles 

recommended by the American Conference of Governmental 

Industrial Hygienists (ACGIH). The process fugitive emissions 

capture systems must be designed to achieve sufficient air 

changes to evacuate the collection area frequently enough to 

ensure process fugitive emissions are effectively collected by

the ventilation system and ducted to the control device(s). 

Include a schematic for each building indicating duct sizes and 

locations, hood sizes and locations, control device types, size 

and locations and exhaust locations. The design plan must 

address variables that affect capture efficiency such as 

operations that create cross-drafts and describe protocol or 

design characteristics to minimize such events. The design plan 

must identify the key operating parameters and measurement 

locations to ensure proper operation of the system and establish 

monitoring parameter values that reflect effective capture. 

(ii) List of critical maintenance actions and the schedule 

to conduct them. 

(2) You must submit a copy of the process fugitive
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emissions ventilation plan to the designated permitting 

authority on or before the applicable compliance date for the 

affected source as specified in §63.1621 in electronic format 

and whenever an update is made to the plan. The requirement for 

you to operate the facility according to the written process 

fugitives ventilation plan and specifications must be 

incorporated in the operating permit for the facility that is 

issued by the designated permitting authority under part 70 of 

this chapter.

(3) You must update the information required in paragraph 

(a)(1) and (a)(2) of this section every 5 years or whenever 

there is a significant change in variables that affect process 

fugitives ventilation design such as the addition of a new 

process.

(b) Outdoor fugitive dust sources. 

(1) You must prepare and at all times operate according to, 

an outdoor fugitive dust control plan that describes in detail 

the measures that will be put in place to control outdoor 

fugitive dust emissions from the individual fugitive dust 

sources at the facility.

(2) You must submit a copy of the outdoor fugitive dust 

control plan to the designated permitting authority on or before 

the applicable compliance date for the affected source as 
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specified in §63.1621. The requirement for you to operate the 

facility according to a written outdoor fugitive dust control 

plan must be incorporated in the operating permit for the 

facility that is issued by the designated permitting authority 

under part 70 of this chapter.

(3) You are permitted to use existing manuals that describe 

the measures in place to control outdoor fugitive dust sources 

required as part of a state implementation plan or other 

federally enforceable requirement for particulate matter to 

satisfy the requirements of paragraph (b)(1) of this section.

8. Section 63.1625 is added to read as follows:

§63.1625 What are the performance test and compliance 

requirements for new, reconstructed and existing facilities?

(a) Performance testing. 

(1) All performance tests must be conducted according to 

the requirements in §63.7 of subpart A.

(2) Each performance test in paragraphs (c)(1) and (c)(2)

must consist of three separate and complete runs using the 

applicable test methods.

(3) Each run must be conducted under conditions that are 

representative of normal process operations.

(4) Performance tests conducted on air pollution control 

devices serving electric arc furnaces must be conducted such 
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that at least one tapping period, or at least 20 minutes of a 

tapping period, whichever is less, is included in at least two 

of the three runs. The sampling time for each run must be at 

least as long as three times the average tapping period of the 

tested furnace, but no less than 60 minutes.

(5) You must conduct the performance tests specified in 

paragraph (c) of this section under such conditions as the 

Administrator specifies based on representative performance of 

the affected source for the period being tested. Upon request, 

you must make available to the Administrator such records as may 

be necessary to determine the conditions of performance tests.

(b) Test methods. The following test methods in appendices 

of part 60 or 63 of this chapter or as specified elsewhere must 

be used to determine compliance with the emission standards.

(1) Method 1 of Appendix A-1 of 40 CFR part 60 to select 

the sampling port location and the number of traverse points.

(2) Method 2 of Appendix A-1 of 40 CFR part 60 to determine 

the volumetric flow rate of the stack gas.

(3)(i) Method 3A or 3B of Appendix A-2 of 40 CFR part 60 

(with integrated bag sampling) to determine the outlet stack and 

inlet oxygen and CO2 content.

(ii) You must measure CO2 concentrations at both the inlet 

and outlet of the positive pressure fabric filter in conjunction 
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with the pollutant sampling in order to determine isokinetic 

sampling rates.

(iii) As an alternative to EPA Reference Method 3B, ASME 

PTC-19-10-1981-Part 10, “Flue and Exhaust Gas Analyses” may be 

used (incorporated by reference, see 40 CFR 63.14).

(4) Method 4 of Appendix A-3 of 40 CFR part 60 to determine 

the moisture content of the stack gas.

(5)(i) Method 5 of Appendix A-3 of 40 CFR part 60 to 

determine the particulate matter concentration of the stack gas 

for negative pressure baghouses and positive pressure baghouses 

with stacks.

(ii) Method 5D of Appendix A-3 of 40 CFR part 60 to 

determine particulate matter concentration and volumetric flow 

rate of the stack gas for positive pressure baghouses without 

stacks.

(iii) The sample volume for each run must be a minimum of 

4.0 cubic meters (141.2 cubic feet). For Method 5 testing only, 

you may choose to collect less than 4.0 cubic meters per run 

provided that the filterable mass collected (e.g., net filter 

mass plus mass of nozzle, probe and filter holder rinses) is 

equal to or greater than 10 mg. If the total mass collected for 

two of three of the runs is less than 10 mg, you must conduct at 

least one additional test run that produces at least 10 mg of 
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filterable mass collected (i.e., at a greater sample volume). 

Report the results of all test runs.

(6) Method 30B of Appendix A-8 of 40 CFR part 60 to measure 

mercury. Apply the minimum sample volume determination 

procedures as per the method.

(7)(i) Method 26A of Appendix A-8 of 40 CFR part 60 to 

determine outlet stack or inlet hydrochloric acid concentration.

(ii) Collect a minimum volume of 2 cubic meters.

(8)(i) Method 316 of Appendix A of 40 CFR part 63 to 

determine outlet stack or inlet formaldehyde.

(ii) Collect a minimum volume of 1.0 cubic meter.

(9) Method 9 of Appendix A-4 of 40 CFR part 60 to determine 

opacity. ASTM D7520-09, “Standard Test Method for Determining 

the Opacity of a Plume in the Outdoor Ambient Atmosphere” may be 

used (incorporated by reference, see 40 CFR 63.14) with the 

following conditions:

(i) During the digital camera opacity technique (DCOT) 

certification procedure outlined in Section 9.2 of ASTM D7520-

09, you or the DCOT vendor must present the plumes in front of 

various backgrounds of color and contrast representing 

conditions anticipated during field use such as blue sky, trees 

and mixed backgrounds (clouds and/or a sparse tree stand).

(ii) You must also have standard operating procedures in 
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place including daily or other frequency quality checks to 

ensure the equipment is within manufacturing specifications as 

outlined in Section 8.1 of ASTM D7520-09.

(iii) You must follow the recordkeeping procedures outlined 

in §63.10(b)(1) for the DCOT certification, compliance report, 

data sheets and all raw unaltered JPEGs used for opacity and 

certification determination.

(iv) You or the DCOT vendor must have a minimum of four (4) 

independent technology users apply the software to determine the 

visible opacity of the 300 certification plumes. For each set of 

25 plumes, the user may not exceed 20 percent opacity of any one 

reading and the average error must not exceed 7.5 percent 

opacity.

(v) Use of this approved alternative does not provide or 

imply a certification or validation of any vendor’s hardware or 

software. The onus to maintain and verify the certification 

and/or training of the DCOT camera, software and operator in 

accordance with ASTM D7520-09 and these requirements is on the 

facility, DCOT operator and DCOT vendor.

(10) Methods to determine the mercury content of manganese 

ore including a total metals digestion technique, SW-846 Method 

3052 and a mercury specific analysis method, SW-846 Method 7471b 

(Cold Vapor AA) or Water Method 1631E (Cold Vapor Atomic 
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Fluorescence).

(11) California Air Resources Board (CARB) Method 429, 

Determination of Polycyclic Aromatic Hydrocarbon (PAH) Emissions 

from Stationary Sources to determine total PAH emissions. The 

method is available from California Resources Board, 1102 Q 

Street, Sacramento, California 95814, 

(http://www.arb.ca.gov/testmeth/vol3/M_429.pdf).

(12) The owner or operator may use alternative measurement 

methods approved by the Administrator following the procedures 

described in §63.7(f) of subpart A.

(c) Compliance demonstration with the emission standards.

(1) Initial Performance Test. You must conduct an initial 

performance test for air pollution control devices or vent 

stacks subject to §63.1623(a), (b)(1) and (c) through (e) to 

demonstrate compliance with the applicable emission standards.

(2) Periodic Performance Test. (i) You must conduct annual 

particulate matter tests for wet scrubber air pollution control 

devices subject to §63.1623(a)(1) to demonstrate compliance with 

the applicable emission standards.

(ii) You must conduct particulate matter tests every five 

years for fabric filter air pollution control devices subject to 

§63.1623(a)(1) to demonstrate compliance with the applicable 

emission standards. 
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(iii) You must conduct annual mercury performance tests for 

wet scrubber and fabric filter air pollution control devices or 

vent stacks subject to §63.1623 (a)(2) to demonstrate compliance 

with the applicable emission standards.

(iv) You must conduct ongoing performance tests every five 

years for air pollution control devices or vent stacks subject 

to §63.1623(a)(3) through (a)(5), (b)(1) and (c) through (e) to 

demonstrate compliance with the applicable emission standards.

(3) Compliance is demonstrated for all sources performing 

emissions tests if the average concentration for the three runs 

comprising the performance test does not exceed the standard.

(4) Operating Limits. You must establish parameter 

operating limits according to paragraphs (c)(4)(i) through 

(c)(4)(iv) of this section. Unless otherwise specified, 

compliance with each established operating limit shall be 

demonstrated for each 24-hour operating day.

(i) For a wet particulate matter scrubber, you must 

establish the minimum liquid flow rate and pressure drop as your 

operating limits during the three-run performance test. If you 

use a wet particulate matter scrubber and you conduct separate 

performance tests for particulate matter, you must establish one 

set of minimum liquid flow rate and pressure drop operating 

limits. If you conduct multiple performance tests, you must set 
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the minimum liquid flow rate and pressure drop operating limits 

at the highest minimum hourly average values established during 

the performance tests.

(ii) For a wet acid gas scrubber, you must establish the 

minimum liquid flow rate and pH, as your operating limits during 

the three-run performance test. If you use a wet acid gas 

scrubber and you conduct separate performance tests for 

hydrochloric acid, you must establish one set of minimum liquid 

flow rate and pH operating limits. If you conduct multiple 

performance tests, you must set the minimum liquid flow rate and 

pH operating limits at the highest minimum hourly average values 

established during the performance tests.

(iii) For emission sources with fabric filters that choose 

to demonstrate continuous compliance through bag leak detection 

systems you must install a bag leak detection system according 

to the requirements in §63.1626(d) and you must set your 

operating limit such that the sum duration of bag leak detection 

system alarms does not exceed 5 percent of the process operating 

time during a 6-month period.

(iv) If you choose to demonstrate continuous compliance 

through a particulate matter CEMS, you must determine an 

operating limit (particulate matter concentration in mg/dscm) 

during performance testing for initial particulate matter 
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compliance. The operating limit will be the average of the PM 

filterable results of the three Method 5 or Method 5D of 

Appendix A-3 of 40 CFR part 60 performance test runs. To 

determine continuous compliance, the hourly average PM 

concentrations will be averaged on a rolling 30 operating day 

basis. Each 30 operating day average would have to meet the PM 

operating limit.

(d) Compliance demonstration with shop building opacity 

standards.

(1)(i) If you are subject to §63.1623(b), you must conduct 

opacity observations of the shop building to demonstrate 

compliance with the applicable opacity standards according to 

§63.6(h)(5), which addresses the conduct of opacity or visible 

emission observations.

(ii) You must conduct the opacity observations according to 

EPA Method 9 of 40 CFR part 60, Appendix A-4, for a period that 

includes at least one complete furnace process cycle for each 

furnace.

(iii) You must conduct the opacity observations at least 

once per week for each operating furnace.

(2) You must determine shop building opacity operating 

parameters based on either monitoring data collected during the 

compliance demonstration or established in an engineering 
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assessment.

(i) If you choose to establish parameters based on the 

initial compliance demonstration, you must simultaneously 

monitor parameter values for one of the following: the capture 

system fan motor amperes and all capture system damper 

positions, the total volumetric flow rate to the air pollution 

control device and all capture system damper positions, or 

volumetric flow rate through each separately ducted hood that 

comprises the capture system. Subsequently you must monitor 

these parameters according to §63.1626(h) and ensure they remain 

within 10 percent of the value recorded during the compliant 

opacity readings.

(ii) If you choose to establish parameters based on an 

engineering assessment, then a design analysis shall include, 

for example, specifications, drawings, schematics and 

ventilation system diagrams prepared by the owner or operator or 

capture or control system manufacturer or vendor that describes 

the shop building opacity system ventilation design based on 

acceptable engineering texts. The design analysis shall address 

vent stream characteristics and ventilation system design 

operating parameters such as fan amps, damper position, flow 

rate and/or other specified parameters.

(iii) You may petition the Administrator to reestablish 
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these parameter ranges whenever you can demonstrate to the 

Administrator's satisfaction that the electric arc furnace 

operating conditions upon which the parameter ranges were 

previously established are no longer applicable. The values of 

these parameter ranges determined during the most recent 

demonstration of compliance must be maintained at the 

appropriate level for each applicable period.

(3) You will demonstrate continuing compliance with the 

opacity standards by following the monitoring requirements 

specified in §63.1626(g) and the reporting and recordkeeping 

requirements specified in §63.1628(b)(5).

(e) Compliance demonstration with the operational and work 

practice standards

(1) Process fugitive emissions sources. You will 

demonstrate compliance by developing and maintaining a process 

fugitives ventilation plan, by reporting any deviations from the 

plan and by taking necessary corrective actions to correct 

deviations or deficiencies.

(2) Outdoor fugitive dust sources. You will demonstrate 

compliance by developing and maintaining an outdoor fugitive 

dust control plan, by reporting any deviations from the plan and 

by taking necessary corrective actions to correct deviations or 

deficiencies.
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(3) Baghouses equipped with bag leak detection systems. You 

will demonstrate compliance with the bag leak detection system 

requirements by developing analysis and supporting documentation 

demonstrating conformance with EPA guidance and specifications 

for bag leak detection systems in §60.57c(h).

9. Section 63.1626 is added to read as follows:

§63.1626 What monitoring requirements must I meet?

(a) Baghouse Monitoring. You must prepare and at all times 

operate according to, a standard operating procedures manual 

that describes in detail procedures for inspection, maintenance

and bag leak detection and corrective action plans for all 

baghouses (fabric filters or cartridge filters) that are used to 

control process vents, process fugitive, or outdoor fugitive 

dust emissions from any source subject to the emissions 

standards in §63.1623. 

(b) You must submit the standard operating procedures 

manual for baghouses required by paragraph (a) of this section 

to the Administrator or delegated authority for review and 

approval.

(c) Unless the baghouse is equipped with a bag leak 

detection system, the procedures that you specify in the 

standard operating procedures manual for inspections and routine 

maintenance must, at a minimum, include the requirements of 
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paragraphs (c)(1) and (c)(2) of this section.

(1) You must observe the baghouse outlet on a daily basis 

for the presence of any visible emissions.

(2) In addition to the daily visible emissions observation, 

you must conduct the following activities:

(i) Weekly confirmation that dust is being removed from 

hoppers through visual inspection, or equivalent means of 

ensuring the proper functioning of removal mechanisms.

(ii) Daily check of compressed air supply for pulse-jet 

baghouses.

(iii) An appropriate methodology for monitoring cleaning 

cycles to ensure proper operation.

(iv) Monthly check of bag cleaning mechanisms for proper 

functioning through visual inspection or equivalent means.

(v) Quarterly visual check of bag tension on reverse air 

and shaker-type baghouses to ensure that the bags are not kinked 

(kneed or bent) or lying on their sides. Such checks are not 

required for shaker-type baghouses using self-tensioning (spring 

loaded) devices.

(vi) Quarterly confirmation of the physical integrity of 

the baghouse structure through visual inspection of the baghouse 

interior for air leaks.

(vii) Semiannual inspection of fans for wear, material 
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buildup and corrosion through visual inspection, vibration 

detectors, or equivalent means.

(d) Bag leak detection system. 

(1) For each baghouse used to control emissions from an 

electric arc furnace, you must install, operate and maintain a 

bag leak detection system according to paragraphs (d)(2) through 

(d)(4) of this section, unless a system meeting the requirements 

of paragraph (q) of this section, for a CEMS and continuous 

emissions rate monitoring system, is installed for monitoring 

the concentration of particulate matter. You may choose to 

install, operate and maintain a bag leak detection system for 

any other baghouse in operation at the facility according to 

paragraphs (d)(2) through (d)(4) of this section.

(2) The procedures you specified in the standard operating 

procedures manual for baghouse maintenance must include, at a 

minimum, a preventative maintenance schedule that is consistent 

with the baghouse manufacturer's instructions for routine and 

long-term maintenance.

(3) Each bag leak detection system must meet the 

specifications and requirements in paragraphs (d)(3)(i) through 

(d)(3)(viii) of this section.

(i) The bag leak detection system must be certified by the 

manufacturer to be capable of detecting PM emissions at 
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concentrations of 1.0 milligram per dry standard cubic meter 

(0.00044 grains per actual cubic foot) or less.

(ii) The bag leak detection system sensor must provide 

output of relative PM loadings. 

(iii) The bag leak detection system must be equipped with 

an alarm system that will alarm when an increase in relative 

particulate loadings is detected over a preset level.

(iv) You must install and operate the bag leak detection 

system in a manner consistent with the guidance provided in 

“Office of Air Quality Planning and Standards (OAQPS) Fabric 

Filter Bag Leak Detection Guidance” EPA-454/R-98-015, September 

1997 (incorporated by reference) and the manufacturer's written 

specifications and recommendations for installation, operation

and adjustment of the system.

(v) The initial adjustment of the system must, at a 

minimum, consist of establishing the baseline output by 

adjusting the sensitivity (range) and the averaging period of 

the device and establishing the alarm set points and the alarm 

delay time.

(vi) Following initial adjustment, you must not adjust the 

sensitivity or range, averaging period, alarm set points, or 

alarm delay time, except as detailed in the approved standard 

operating procedures manual required under paragraph (a) of this 
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section. You cannot increase the sensitivity by more than 100 

percent or decrease the sensitivity by more than 50 percent over 

a 365-day period unless such adjustment follows a complete 

baghouse inspection that demonstrates that the baghouse is in 

good operating condition.

(vii) You must install the bag leak detector downstream of 

the baghouse.

(viii) Where multiple detectors are required, the system's 

instrumentation and alarm may be shared among detectors.

(4) You must include in the standard operating procedures 

manual required by paragraph (a) of this section a corrective 

action plan that specifies the procedures to be followed in the 

case of a bag leak detection system alarm. The corrective action 

plan must include, at a minimum, the procedures that you will 

use to determine and record the time and cause of the alarm as 

well as the corrective actions taken to minimize emissions as 

specified in paragraphs (d)(4)(i) and (d)(4)(ii) of this 

section.

(i) The procedures used to determine the cause of the alarm 

must be initiated within 30 minutes of the alarm.

(ii) The cause of the alarm must be alleviated by taking 

the necessary corrective action(s) that may include, but not be 

limited to, those listed in paragraphs (d)(4)(i)(A) through 
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(d)(4)(i)(F) of this section.

(A) Inspecting the baghouse for air leaks, torn or broken 

filter elements, or any other malfunction that may cause an 

increase in emissions.

(B) Sealing off defective bags or filter media.

(C) Replacing defective bags or filter media, or otherwise 

repairing the control device.

(D) Sealing off a defective baghouse compartment.

(E) Cleaning the bag leak detection system probe, or 

otherwise repairing the bag leak detection system.

(F) Shutting down the process producing the particulate 

emissions.

(e) If you use a wet particulate matter scrubber, you must 

collect the pressure drop and liquid flow rate monitoring system 

data according to §63.1628, reduce the data to 24-hour block 

averages and maintain the 24-hour average pressure drop and 

liquid flow-rate at or above the operating limits established 

during the performance test according to §63.1625(c)(4)(i).

(f) If you use curtains or partitions to prevent process 

fugitive emissions from escaping the area around the process 

fugitive emission source or other parts of the building, you 

must perform quarterly inspections of the physical condition of 

these curtains or partitions to determine if there are any tears 
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or openings.

(g) Shop building opacity. In order to demonstrate 

continuous compliance with the opacity standards in §63.1623, 

you must comply with the requirements §63.1625(d)(1) and one of 

the monitoring options in paragraphs (g)(1) or (g)(2) of this 

section. The selected option must be consistent with that 

selected during the initial performance test described in 

§63.1625(d)(2). Alternatively, you may use the provisions of 

§63.8(f) to request approval to use an alternative monitoring 

method.

(1) If you choose to establish operating parameters during 

the compliance test as specified in §63.1625(d)(2)(i), you must 

meet one of the following requirements.

(i) Check and record the control system fan motor amperes 

and capture system damper positions once per shift.

(ii) Install, calibrate and maintain a monitoring device 

that continuously records the volumetric flow rate through each 

separately ducted hood.

(iii) Install, calibrate and maintain a monitoring device 

that continuously records the volumetric flow rate at the inlet 

of the air pollution control device and check and record the 

capture system damper positions once per shift.

(2) If you choose to establish operating parameters during 
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the compliance test as specified in §63.1625(d)(2)(ii), you must 

monitor the selected parameter(s) on a frequency specified in 

the assessment and according to a method specified in the 

engineering assessment

(3) All flow rate monitoring devices must meet the 

following requirements:

(i) Be installed in an appropriate location in the exhaust 

duct such that reproducible flow rate monitoring will result.

(ii) Have an accuracy ±10 percent over its normal operating 

range and be calibrated according to the manufacturer's 

instructions.

(4) The Administrator may require you to demonstrate the 

accuracy of the monitoring device(s) relative to Methods 1 and 2 

of Appendix A-1 of part 60 of this chapter.

(5) Failure to maintain the appropriate capture system 

parameters (e.g., fan motor amperes, flow rate and/or damper 

positions) establishes the need to initiate corrective action as 

soon as practicable after the monitoring excursion in order to 

minimize excess emissions.

(h) Furnace Capture System. You must perform quarterly 

(once every three months) inspections of the furnace fugitive 

capture system equipment to ensure that the hood locations have

not been changed or obstructed because of contact with cranes or 
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ladles, quarterly inspections of the physical condition of hoods 

and ductwork to the control device to determine if there are any 

openings or leaks in the ductwork, quarterly inspections of the 

hoods and ductwork to determine if there are any flow 

constrictions in ductwork due to dents or accumulated dust and

quarterly examinations of the operational status of flow rate 

controllers (pressure sensors, dampers, damper switches, etc.) 

to ensure they are operating correctly. Any deficiencies must be 

recorded and proper maintenance and repairs performed.

(i) Requirements for sources using CMS. If you demonstrate 

compliance with any applicable emissions limit through use of a 

continuous monitoring system (CMS), where a CMS includes a 

continuous parameter monitoring system (CPMS) as well as a 

continuous emissions monitoring system (CEMS), you must develop 

a site-specific monitoring plan and submit this site-specific 

monitoring plan, if requested, at least 60 days before your 

initial performance evaluation (where applicable) of your CMS. 

Your site-specific monitoring plan must address the monitoring 

system design, data collection and the quality assurance and 

quality control elements outlined in this section and in 

§63.8(d). You must install, operate and maintain each CMS 

according to the procedures in your approved site-specific 

monitoring plan. Using the process described in §63.8(f)(4), you 
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may request approval of monitoring system quality assurance and 

quality control procedures alternative to those specified in 

paragraphs (j)(1) through (j)(6) of this section in your sitespecific monitoring plan.

(1) The performance criteria and design specifications for 

the monitoring system equipment, including the sample interface, 

detector signal analyzer and data acquisition and calculations;

(2) Sampling interface location such that the monitoring 

system will provide representative measurements; 

(3) Equipment performance checks, system accuracy audits, 

or other audit procedures;

(4) Ongoing operation and maintenance procedures in 

accordance with the general requirements of §63.8(c)(1) and 

(c)(3);

(5) Conditions that define a continuous monitoring system 

that is out of control consistent with §63.8(c)(7)(i) and for 

responding to out of control periods consistent with 

§63.8(c)(7)(ii) and (c)(8) or Appendix A to this subpart, as 

applicable; and

(6) Ongoing recordkeeping and reporting procedures in 

accordance with provisions in §63.10(c), (e)(1) and (e)(2)(i) 

and Appendix A to this subpart, as applicable.

(j) If you have an operating limit that requires the use of 
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a CPMS, you must install, operate and maintain each continuous 

parameter monitoring system according to the procedures in 

paragraphs (j)(1) through (j)(7) of this section.

(1) The continuous parameter monitoring system must 

complete a minimum of one cycle of operation for each successive 

15-minute period. You must have a minimum of four successive 

cycles of operation to have a valid hour of data.

(2) Except for periods of monitoring system malfunctions, 

repairs associated with monitoring system malfunctions and

required monitoring system quality assurance or quality control 

activities (including, as applicable, system accuracy audits and 

required zero and span adjustments), you must operate the CMS at 

all times the affected source is operating. A monitoring system 

malfunction is any sudden, infrequent, not reasonably 

preventable failure of the monitoring system to provide valid 

data. Monitoring system failures that are caused in part by poor 

maintenance or careless operation are not malfunctions. You are 

required to complete monitoring system repairs in response to 

monitoring system malfunctions and to return the monitoring 

system to operation as expeditiously as practicable. 

(3) You may not use data recorded during monitoring system 

malfunctions, repairs associated with monitoring system 

malfunctions, or required monitoring system quality assurance or 
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control activities in calculations used to report emissions or 

operating levels. You must use all the data collected during all 

other required data collection periods in assessing the 

operation of the control device and associated control system. 

(4) Except for periods of monitoring system malfunctions, 

repairs associated with monitoring system malfunctions and

required quality monitoring system quality assurance or quality 

control activities (including, as applicable, system accuracy 

audits and required zero and span adjustments), failure to 

collect required data is a deviation of the monitoring 

requirements.

(5) You must conduct other CPMS equipment performance 

checks, system accuracy audits, or other audit procedures 

specified in your site-specific monitoring plan at least once 

every 12 months.

(6) You must conduct a performance evaluation of each CPMS 

in accordance with your site-specific monitoring plan.

(7) You must record the results of each inspection, 

calibration and validation check.

(k) CPMS for measuring gaseous flow.

(1) Use a flow sensor with a measurement sensitivity of 5 

percent of the flow rate or 10 cubic feet per minute, whichever 

is greater,
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(2) Check all mechanical connections for leakage at least 

every month and

(3) Perform a visual inspection at least every 3 months of 

all components of the flow CPMS for physical and operational 

integrity and all electrical connections for oxidation and 

galvanic corrosion if your flow CPMS is not equipped with a 

redundant flow sensor. 

(l) CPMS for measuring liquid flow.

(1) Use a flow sensor with a measurement sensitivity of 2 

percent of the flow rate and

(2) Reduce swirling flow or abnormal velocity distributions 

due to upstream and downstream disturbances.

(m) CPMS for measuring pressure.

(1) Minimize or eliminate pulsating pressure, vibration and

internal and external corrosion and

(2) Use a gauge with a minimum tolerance of 1.27 

centimeters of water or a transducer with a minimum tolerance of 

1 percent of the pressure range.

(3) Perform checks at least once each process operating day 

to ensure pressure measurements are not obstructed (e.g., check 

for pressure tap pluggage daily).

(n) CPMS for measuring pH.

(1) Ensure the sample is properly mixed and representative 
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of the fluid to be measured.

(2) Check the pH meter's calibration on at least two points 

every eight hours of process operation.

(o) Particulate Matter CEMS. If you are using a CEMS to 

measure particulate matter emissions to meet requirements of 

this subpart, you must install, certify, operate and maintain 

the particulate matter CEMS as specified in paragraphs (q)(1) 

through (q)(4) of this section.

(1) You must conduct a performance evaluation of the PM 

CEMS according to the applicable requirements of §60.13 and

Performance Specification 11 at 40 CFR part 60, Appendix B of 

this chapter.

(2) During each PM correlation testing run of the CEMS 

required by Performance Specification 11 at 40 CFR part 60, 

Appendix B of this chapter, PM and oxygen (or carbon dioxide) 

collect data concurrently (or within a 30-to 60-minute period) 

by both the CEMS and by conducting performance tests using 

Method 5 or 5D at 40 CFR part 60, Appendix A–3 or Method 17 at 

40 CFR part 60, Appendix A–6 of this chapter.

(3) Perform quarterly accuracy determinations and daily 

calibration drift tests in accordance with Procedure 2 at 40 CFR 

part 60, Appendix F of this chapter. Relative Response Audits 

must be performed annually and Response Correlation Audits must 
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be performed every three years.

(4) Within 60 days after the date of completing each CEMS 

relative accuracy test audit or performance test conducted to 

demonstrate compliance with this subpart, you must submit the 

relative accuracy test audit data and the results of the 

performance test in the as specified in §63.1628(e).

10. Section 63.1627 is added to read as follows:

§63.1627

What notification requirements must I meet?

(a) You must comply with all of the notification 

requirements of §63.9 of subpart A, General Provisions. 

Electronic notifications are encouraged when possible. 

(b)(1) You must submit the process fugitives ventilation 

plan required under §63.1624(a), the outdoor fugitive dust 

control plan required under §63.1624(b), the site-specific 

monitoring plan for CMS required under §63.1626(i) and the 

standard operating procedures manual for baghouses required 

under §63.1626(a) to the Administrator or delegated authority 

along with a notification that you are seeking review and 

approval of these plans and procedures. You must submit this 

notification no later than [INSERT DATE OF 1 YEAR AFTER 

EFFECTIVE DATE OF FINAL RULE]. For sources that commenced 

construction or reconstruction after [INSERT DATE OF EFFECTIVE 
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DATE OF FINAL RULE], you must submit this notification no later 

than 180 days before startup of the constructed or reconstructed 

ferromanganese or silicomanganese production facility. For an 

affected source that has received a construction permit from the 

Administrator or delegated authority on or before [INSERT DATE 

OF EFFECTIVE DATE OF FINAL RULE], you must submit this 

notification no later than [INSERT DATE OF 1 YEAR AFTER 

EFFECTIVE DATE OF FINAL RULE].

(2) The plans and procedures documents submitted as 

required under paragraph (b)(1) of this section must be 

submitted to the Administrator in electronic format for review 

and approval of the initial submittal and whenever an update is 

made to the procedure.

11. Section 63.1628 is added to read as follows:

§63.1628

What recordkeeping and reporting requirements must I meet?

(a) You must comply with all of the recordkeeping and 

reporting requirements specified in §63.10 of the General 

Provisions that are referenced in Table 1 to this subpart.

(1) Records must be maintained in a form suitable and 

readily available for expeditious review, according to 

§63.10(b)(1). However, electronic recordkeeping and reporting is 

encouraged and required for some records and reports. 
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(2) Records must be kept on site for at least two years 

after the date of occurrence, measurement, maintenance, 

corrective action, report, or record, according to §63.10(b)(1). 

(b) You must maintain, for a period of five years, records 

of the information listed in paragraphs (b)(1) through (b)(13) 

of this section.

(1) Electronic records of the bag leak detection system 

output.

(2) An identification of the date and time of all bag leak 

detection system alarms, the time that procedures to determine 

the cause of the alarm were initiated, the cause of the alarm, 

an explanation of the corrective actions taken and the date and 

time the cause of the alarm was corrected. 

(3) All records of inspections and maintenance activities 

required under §63.1626(a) as part of the practices described in 

the standard operating procedures manual for baghouses required 

under §63.1626(c).

(4) Electronic records of the pressure drop and water flow 

rate values for wet scrubbers used to control particulate matter 

emissions as required in §63.1626(e), identification of periods 

when the 1-hour average pressure drop and water flow rate values 

below the established minimum established and an explanation of 

the corrective actions taken.
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(5) Electronic records of the shop building capture system 

monitoring required under §63.1626(g)(1) and (g)(2), as 

applicable, or identification of periods when the capture system 

parameters were not maintained and an explanation of the 

corrective actions taken.

(6) Records of the results of quarterly inspections of the 

furnace capture system required under §63.1626(h).

(7) Electronic records of the continuous flow monitors or 

pressure monitors required under §63.1626(j) and (k) and an 

identification of periods when the flow rate or pressure was not 

maintained as required in §63.1626(e).

(8) Electronic records of the output of any CEMS installed 

to monitor particulate matter emissions meeting the requirements 

of §63.1626(i)

(9) Records of the occurrence and duration of each startup 

and/or shutdown.

(10) Records of the occurrence and duration of each 

malfunction of operation (i.e., process equipment) or the 

air pollution control equipment and monitoring equipment. 

(11) Records that explain the periods when the procedures 

outlined in the process fugitives ventilation plan required 

under §63.1624(a), the fugitives dust control plan required 

under §63.1624(b), the site-specific monitoring plan for CMS 
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required under §63.1626(i) and the standard operating procedures 

manual for baghouses required under §63.1626(a).

(c) You must comply with all of the reporting requirements 

specified in §63.10 of the General Provisions that are 

referenced in Table 1 to this subpart. 

(1) You must submit reports no less frequently than 

specified under §63.10(e)(3) of the General Provisions. 

(2) Once a source reports a violation of the standard or 

excess emissions, you must follow the reporting format required 

under §63.10(e)(3) until a request to reduce reporting frequency 

is approved by the Administrator.

(d) In addition to the information required under the 

applicable sections of §63.10, you must include in the reports 

required under paragraph (c) of this section the information 

specified in paragraphs (d)(1) through (d)(7) of this section.

(1) Reports that explain the periods when the procedures 

outlined in the process fugitives ventilation plan required 

under §63.1624(a), the fugitives dust control plan required 

under §63.1624(b), the site-specific monitoring plan for CMS 

required under §63.1626(i) and the standard operating procedures 

manual for baghouses required under §63.1626(a).

(2) Reports that identify the periods when the average 

hourly pressure drop or flow rate of venturi scrubbers used to 
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control particulate emissions dropped below the levels 

established in §63.1626(e) and an explanation of the corrective 

actions taken.

(3) Bag leak detection system. Reports including the 

following information:

(i) Records of all alarms.

(ii) Description of the actions taken following each bag 

leak detection system alarm.

(4) Reports of the shop building capture system monitoring 

required under §63.1626(g)(1) and (g)(2), as applicable, 

identification of periods when the capture system parameters 

were not maintained and an explanation of the corrective actions 

taken.

(5) Reports of the results of quarterly inspections of the 

furnace capture system required under §63.1626(h).

(6) Reports of the CPMS required under §63.1626, an 

identification of periods when the monitored parameters were not 

maintained as required in §63.1626 and corrective actions taken.

(7) If a malfunction occurred during the reporting period, 

the report must include the number, duration and a brief 

description for each type of malfunction that occurred during 

the reporting period and caused or may have caused any 

applicable emissions limitation to be exceeded. The report must 
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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 §63.1623(f), including actions 

taken to correct a malfunction. 

(e) Within 60 days after the date of completing each CEMS 

relative accuracy test audit or performance test conducted to 

demonstrate compliance with this subpart, you must submit the 

relative accuracy test audit data and the results of the 

performance test in the method specified by paragraphs (e)(1) 

through (e)(2) of this section. The results of the performance 

test must contain the information listed in paragraph (e)(2) of 

this section.

(1)(i) Within 60 days after the date of completing each 

performance test (as defined in §63.2), you must submit the 

results of the performance tests, including any associated fuel 

analyses, required by this subpart according to the methods 

specified in paragraphs (e)(1)(i)(A) or (e)(1)(i)(B) of this 

section.

(A) For data collected using test methods supported by the 

EPA’s Electronic Reporting Tool (ERT) as listed on the EPA’s ERT 

website (http://www.epa.gov/ttn/chief/ert/index.html), you must 

submit the results of the performance test to the Compliance and 

Emissions Data Reporting Interface (CEDRI) that is accessed 
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through the EPA’s Central Data Exchange (CDX) 

(http://cdx.epa.gov/epa_home.asp), unless the Administrator 

approves another approach. Performance test data must be 

submitted in a file format generated through the use of the 

EPA’s ERT. Owners or operators, who claim that some of the 

information being submitted for performance tests is 

confidential business information (CBI), must submit a complete 

file generated through the use of the EPA’s ERT, including 

information claimed to be CBI, on a compact disk, flash drive, 

or other commonly used electronic storage media to the EPA.. The 

electronic media must be clearly marked as CBI and mailed to 

U.S. EPA/OAQPS/CORE CBI Office, Attention: WebFIRE 

Administrator, MD C404-02, 4930 Old Page Rd., Durham, NC 27703.

The same ERT file with the CBI omitted must be submitted to the 

EPA via CDX as described earlier in this paragraph. 

(B) For any performance test conducted using test methods 

that are not supported by the EPA’s ERT as listed on the EPA’s 

ERT website, the owner or operator shall submit the results of 

the performance test to the Administrator at the appropriate 

address listed in §63.13.

(ii) Within 60 days after the date of completing each CEMS 

performance evaluation (as defined in §63.2), you must submit 

the results of the performance evaluation according to the 
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method specified by either paragraph (b)(1) or (b)(2) of this 

section. 

(A) For data collection of relative accuracy test audit 

(RATA) pollutants that are supported by the EPA’s ERT as listed 

on the EPA’s ERT website, you must submit the results of the 

performance evaluation to the CEDRI that is accessed through the 

EPA’s CDX, unless the Administrator approves another approach. 

Performance evaluation data must be submitted in a file format 

generated through the use of the EPA’s ERT. If you claim that 

some of the performance evaluation information being transmitted 

is CBI, you must submit a complete file generated through the 

use of the EPA’s ERT, including information claimed to be CBI, 

on a compact disk or other commonly used electronic storage 

media (including, but not limited to, flash drives) by 

registered letter to the EPA. The compact disk shall be clearly 

marked as CBI and mailed to U.S. EPA/OAQPS/CORE CBI Office, 

Attention: WebFIRE Administrator, MD C404-02, 4930 Old Page Rd., 

Durham, NC 27703. The same ERT file with the CBI omitted must 

be submitted to the EPA via CDX as described earlier in this 

paragraph.

(B) For any performance evaluations with RATA pollutants 

that are not supported by the EPA’s ERT as listed on the EPA’s 

ERT website, you shall submit the results of the performance 
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evaluation to the Administrator at the appropriate address 

listed in §63.13.

(2) The results of a performance test shall include the 

purpose of the test; a brief process description; a complete 

unit description, including a description of feed streams and 

control devices; sampling site description; pollutants measured; 

description of sampling and analysis procedures and any 

modifications to standard procedures; quality assurance 

procedures; record of operating conditions, including operating 

parameters for which limits are being set, during the test; 

record of preparation of standards; record of calibrations; raw 

data sheets for field sampling; raw data sheets for field and 

laboratory analyses; chain-of-custody documentation; explanation 

of laboratory data qualifiers; example calculations of all 

applicable stack gas parameters, emission rates, percent 

reduction rates and analytical results, as applicable; and any 

other information required by the test method, a relevant 

standard, or the Administrator.

12. Section 63.1629 is added to read as follows:

§63.1629 Who implements and enforces this subpart?

(a) This subpart can be implemented and enforced by the 

U.S. EPA, or a delegated authority such as the applicable state, 

local, or tribal agency. If the U.S. EPA Administrator has 
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delegated authority to a state, local, or tribal agency, then 

that agency, in addition to the U.S. EPA, has the authority to 

implement and enforce this subpart. Contact the applicable U.S. 

EPA Regional Office to find out if this subpart is delegated to 

a state, local, or tribal agency.

(b) In delegating implementation and enforcement authority 

of this subpart to a state, local, or tribal agency under 

subpart E of this part, the authorities contained in paragraph 

(c) of this section are retained by the Administrator of U.S. 

EPA and cannot be transferred to the state, local, or tribal 

agency.

(c) The authorities that cannot be delegated to state, 

local, or tribal agencies are as specified in paragraphs (c)(1) 

through (c)(4) of this section.

(1) Approval of alternatives to requirements in §§63.1620 

and 63.1621 and 63.1623 and 63.1624.

(2) Approval of major alternatives to test methods under 

§63.7(e)(2)(ii) and (f), as defined in §63.90 and as required in 

this subpart.

(3) Approval of major alternatives to monitoring under 

§63.8(f), as defined in §63.90 and as required in this subpart.

(4) Approval of major alternatives to recordkeeping and 

reporting under §63.10(f), as defined in §63.90 and as required 
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in this subpart.

13. Section 63.1650 is amended by:

a. Revising paragraph (d);

b. Removing and reserving paragraph (e)(1); and

c. Revising paragraph (e)(2) to read as follows:

§63.1650 Applicability and Compliance Dates.

* * * * *

(d) Table 1 to this subpart specifies the provisions of 

subpart A of this part that apply to owners and operators of 

ferroalloy production facilities subject to this subpart.

(e) * * *

(1) [Reserved]

(2) Each owner or operator of a new or reconstructed 

affected source that commences construction or reconstruction 

after August 4, 1998 and before [INSERT DATE OF PUBLICATION OF 

THE PROPOSED RULE IN THE FEDERAL REGISTER], must comply with the 

requirements of this subpart by May 20,1999 or upon startup of 

operations, whichever is later.

14. Section 63.1652 is amended by adding paragraph (f) to read 

as follows:

§63.1652 Emission standards. 

* * * * *

(f) At all times, you must operate and maintain any 
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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 that 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.

15. Section 63.1656 is amended by:

a. Adding paragraph (a)(6);

b. Revising paragraph (b)(7);

c. Revising paragraph (e)(1); and

d. Removing and reserving paragraph (e)(2)(ii) to read as 

follows:

§63.1656 Performance testing, test methods and compliance 

demonstrations.

(a) * * *

(6) You must conduct the performance tests specified in 

paragraph (c) of this section under such conditions as the 

Administrator specifies based on representative performance of 

the affected source for the period being tested. Upon request, 

you must make available to the Administrator such records as may 
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be necessary to determine the conditions of performance tests.

* * * * * 

(b)(7) Method 9 of Appendix A-4 of 40 CFR part 60 to 

determine opacity. ASTM D7520-09, “Standard Test Method for 

Determining the Opacity of a Plume in the Outdoor Ambient 

Atmosphere” may be used (incorporated by reference, see 40 CFR 

63.14) with the following conditions:

(i) During the digital camera opacity technique (DCOT) 

certification procedure outlined in Section 9.2 of ASTM D7520-

09, the owner or operator or the DCOT vendor must present the 

plumes in front of various backgrounds of color and contrast 

representing conditions anticipated during field use such as 

blue sky, trees and mixed backgrounds (clouds and/or a sparse 

tree stand).

(ii) The owner or operator must also have standard 

operating procedures in place including daily or other frequency 

quality checks to ensure the equipment is within manufacturing 

specifications as outlined in Section 8.1 of ASTM D7520-09.

(iii) The owner or operator must follow the recordkeeping 

procedures outlined in §63.10(b)(1) for the DCOT certification, 

compliance report, data sheets and all raw unaltered JPEGs used 

for opacity and certification determination.

(iv) The owner or operator or the DCOT vendor must have a 
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minimum of four (4) independent technology users apply the 

software to determine the visible opacity of the 300 

certification plumes. For each set of 25 plumes, the user may 

not exceed 15 percent opacity of any one reading and the average 

error must not exceed 7.5 percent opacity.

(v) Use of this approved alternative does not provide or 

imply a certification or validation of any vendor’s hardware or

software. The onus to maintain and verify the certification 

and/or training of the DCOT camera, software and operator in 

accordance with ASTM D7520-09 and these requirements is on the 

facility, DCOT operator and DCOT vendor. 

* * * * *

(e) * * * 

(1) Fugitive dust sources. Failure to have a fugitive dust 

control plan or failure to report deviations from the plan and 

take necessary corrective action would be a violation of the 

general duty to ensure that fugitive dust sources are operated 

and maintained in a manner consistent with good air pollution 

control practices for minimizing emissions per §63.1652(f).

(2) * * *

(ii) [Reserved]

* * * * *

16. Section 63.1657 is amended by:
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a. Revising paragraph (a)(6);

b. Revising paragraph (b)(3); and

c. Revising paragraph (c)(7) to read as follows:

§63.1657 Monitoring requirements.

(a) * * *

(6) Failure to monitor or failure to take corrective action 

under the requirements of paragraph (a) of this section would be 

a violation of the general duty to operate in a manner 

consistent with good air pollution control practices that 

minimizes emissions per §63.1652(f).

(b) * * * 

(3) Failure to monitor or failure to take corrective action 

under the requirements of paragraph (b) of this section would be 

a violation of the general duty to operate in a manner 

consistent with good air pollution control practices that 

minimizes emissions per §63.1652(f).

(c) * * *

(7) Failure to monitor or failure to take corrective action 

under the requirements of paragraph (c) of this section would be 

a violation of the general duty to operate in a manner 

consistent with good air pollution control practices that 

minimizes emissions per §63.1652(f).

17. Section 63.1659 is amended by revising paragraph (a)(4) to 
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read as follows:

(a) * * *

(4) Reporting malfunctions. If a malfunction occurred 

during the reporting period, the report must include 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 

§63.1652(f), including actions taken to correct a malfunction.

* * * * *

18. Section 63.1660 is amended by:

a. Revising paragraphs (a)(2)(i) and (a)(2)(ii); and 

b. Removing and reserving paragraphs (a)(2)(iv) and (a)(2)(v) to 

read as follows:

(a) * * *

(2) * * *

(i) Records of the occurrence and duration of each 

malfunction of operation (i.e., process equipment) or the air 

pollution control equipment and monitoring equipment;

(ii) Records of actions taken during periods of malfunction 

to minimize emissions in accordance with §63.1652(f), including 
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corrective actions to restore malfunctioning process and air 

pollution control and monitoring equipment to its normal or 

usual manner of operation;

* * * * *

(iv) [Reserved]

(v) [Reserved]

* * * * *

19. Add Table 1 to the end of subpart XXX to read as follows:

Table 1 to Subpart XXX of Part 63—General Provisions 

Applicability to Subpart XXX

Reference Applies to 

subpart 

XXX

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 63.1623(g) and 

63.1652(f) for 

general duty 

requirement. 

63.6(e)(1)(ii) No

63.6(e)(1)(iii) Yes

63.6(e)(2) No Section reserved.

63.6(e)(3) No

63.6(f)(1) No

6.6(f)(2) – (f)(3) Yes

63.6(g) Yes

63.6(h)(1) No

63.6(h)(2) – (h)(9) Yes .

63.6(i) Yes

63.6(j) Yes

§63.7(a)-(d) Yes

§63.7(e)(1) No See 63.1625(a)(5) 
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Reference Applies to 

subpart 

XXX

Comment

and 63.1656(a)(6)

§63.7(e)(2)-(e)(4) Yes

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

63.8(a)-(b) Yes

63.8(c)(1)(i) No See 63.1623(g) and 

63.1652(f) for 

general duty 

requirement. 

63.8(c)(1)(ii) Yes

63.8(c)(1)(iii) No

63.8(c)(2)-(d)(2) Yes

63.8(d)(3) Yes, 

except for 

last 

sentence

SSM plans are not 

required.

63.8(e)-(g) Yes

63.9(a),(b),(c),(e),(g),(h)(1)t

hrough (3), (h)(5) and (6), (i) 

and (j)

Yes

63.9(f) Yes

63.9(h)(4) No Reserved

63.10 (a) Yes

63.10 (b)(1) Yes

63.10(b)(2)(i) No

63.10(b)(2)(ii) No See 63.1628 and 

63.1660 for 

recordkeeping of (1) 

occurrence and 

duration and (2) 

actions taken during 

malfunction. 

63.10(b)(2)(iii) Yes

63.10(b)(2)(iv)-(b)(2)(v) No

63.10(b)(2)(vi)-(b)(2)(xiv) Yes

63.10)(b)(3) Yes

63.10(c)(1)-(9) Yes

63.10(c)(10)-(11) No See 63.1628 and 

63.1660 for 

malfunction 

recordkeeping 

requirements. 

63.10(c)(12)-(c)(14) Yes
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Reference Applies to 

subpart 

XXX

Comment

63.10(c)(15) No

63.10(d)(1)-(4) Yes

63.10(d)(5) No See 63.1628(d)(8) 

and 63.1659(a)(4) 

for malfunction 

reporting 

requirements.

63.10(e)-((f) Yes

63.11 No Flares will not be 

used to comply with 

the emission limits

63.12 to 63.15 Yes