National Emission Standards for Hazardous Air Pollutants for Area Sources: Industrial, Commercial, and Institutional Boilers, 31896-31935 [2010-10832]

Agencies

• ENVIRONMENTAL PROTECTION AGENCY

[Federal Register Volume 75, Number 107 (Friday, June 4, 2010)]
[Proposed Rules]
[Pages 31896-31935]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2010-10832]



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Part III





Environmental Protection Agency





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40 CFR Part 63



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National Emission Standards for Hazardous Air Pollutants for Area 
Sources: Industrial, Commercial, and Institutional Boilers; Proposed 
Rule

Federal Register / Vol. 75, No. 107 / Friday, June 4, 2010 / Proposed 
Rules

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 63

[EPA-HQ-OAR-2006-0790; FRL-9148-3]
RIN 2060-AM44


National Emission Standards for Hazardous Air Pollutants for Area 
Sources: Industrial, Commercial, and Institutional Boilers

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: EPA is proposing national emission standards for control of 
hazardous air pollutants from two area source categories: Industrial 
boilers and commercial and institutional boilers. The proposed emission 
standards for control of mercury emissions from coal-fired area source 
boilers and the proposed emission standards for control of polycyclic 
organic matter emissions from all area source boilers are based on the 
maximum achievable control technology. The proposed emission standards 
for control of mercury emissions from biomass-fired and oil-fired area 
source boilers and for other hazardous air pollutants are based on 
EPA's proposed determination as to what constitutes the generally 
available control technology or management practices.
    EPA is also clarifying that gas-fired area source boilers are not 
needed to meet the 90 percent requirement of section 112(c)(3) of the 
Clean Air Act.
    Finally, we are also proposing that existing area source facilities 
with an affected boiler with a designed heat input capacity of 10 
million Btu per hour or greater undergo an energy assessment on the 
boiler system to identify cost-effective energy conservation measures.

DATES: Comments must be received on or before July 19, 2010. Under the 
Paperwork Reduction Act, comments on the information collection 
provisions are best assured of having full effect if the Office of 
Management and Budget (OMB) receives a copy of your comments on or 
before July 6, 2010.
    Public Hearing. We will hold a public hearing concerning this 
proposed rule and the interrelated proposed Boiler major source, CISWI, 
and RCRA rules, discussed in this proposal and published in the 
proposed rules section of today's Federal Register, on June 21, 2010. 
Persons requesting to speak at a public hearing must contact EPA by 
June 14, 2010.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-HQ-
OAR-2006-0790, by one of the following methods:
     https://www.regulations.gov. Follow the instructions for 
submitting comments.
     https://www.epa.gov/oar/docket.html. Follow the 
instructions for submitting comments on the EPA Air and Radiation 
Docket Web site.
     E-mail: Comments may be sent by electronic mail (e-mail) 
to a-and-r-docket@epa.gov, Attention Docket ID No. EPA-HQ-OAR-2006-
0790.
     Fax: Fax your comments to: (202) 566-9744, Docket ID No. 
EPA-HQ-OAR-2006-0790.
     Mail: Send your comments to: EPA Docket Center (EPA/DC), 
Environmental Protection Agency, Mailcode: 2822T, 1200 Pennsylvania 
Ave., NW., Washington, DC 20460, Docket ID No. EPA-HQ-OAR-2006-0790. 
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, OMB, Attn: Desk Officer for EPA, 
725 17th St., NW., Washington, DC 20503.
     Hand Delivery or Courier: Deliver your comments to: EPA 
Docket Center (EPA/DC), EPA West, Room 3334, 1301 Constitution Ave., 
NW., Washington, DC 20460. Attention Docket ID No. EPA-HQ-OAR-2006-
0790. Such deliveries are only accepted during the Docket's normal 
hours of operation (8:30 a.m. to 4:30 p.m., Monday through Friday, 
excluding legal holiday), and special arrangements should be made for 
deliveries of boxed information.
    Instructions: All submissions must include agency name and docket 
number or Regulatory Information Number (RIN) for this rulemaking. All 
comments will be posted without change and may be made available online 
at https://www.regulations.gov, including any personal information 
provided, unless the comment includes information claimed to be 
confidential business information (CBI) or other information whose 
disclosure is restricted by statute. Do not submit information that you 
consider to be CBI or otherwise protected through https://www.regulations.gov or e-mail. The https://www.regulations.gov Web site 
is an ``anonymous access'' system, which means EPA will not know your 
identity or contact information unless you provide it in the body of 
your comment. If you send an e-mail comment directly to EPA without 
going through https://www.regulations.gov, your e-mail 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, EPA recommends that you include your name 
and other contact information in the body of your comment and with any 
disk or CD-ROM you submit. If EPA cannot read your comment due to 
technical difficulties and cannot contact you for clarification, EPA 
may not be able to consider your comment. Electronic files should avoid 
the use of special characters, any form of encryption, and be free of 
any defects or viruses.
    Public Hearing: We will hold a public hearing concerning this 
proposed rule on June 21, 2010. Persons interested in presenting oral 
testimony at the hearing should contact Ms. Pamela Garrett, Energy 
Strategies Group, at (919) 541-7966 by June 14, 2010. The public 
hearing will be held in the Washington, DC area at a location and time 
that will be posted at the following Web site: https://www.epa.gov/airquality/combustion. Please refer to this Web site to confirm the 
date of the public hearing as well. If no one requests to speak at the 
public hearing by June 14, 2010 then the public hearing will be 
cancelled and a notification of cancellation posted on the following 
Web site: https://www.epa.gov/airquality/combustion.
    Docket: All documents in the docket are listed in the https://www.regulations.gov index. Although listed in the index, some 
information is not publicly available, e.g., CBI or other information 
whose disclosure is restricted by statute. Certain other material, such 
as copyrighted material, will be publicly available only in hard copy 
form. Publicly available docket materials are available either 
electronically in https://www.regulations.gov or in hard copy at the EPA 
Docket Center, Room 3334, 1301 Constitution Ave., NW., Washington, DC. 
The Public Reading Room is open from 8:30 a.m. to 4:30 p.m., Monday 
through Friday, excluding legal holidays. The telephone number for the 
Public Reading Room is (202) 566-1744, and the telephone number for the 
Air Docket is (202) 566-1742.

FOR FURTHER INFORMATION CONTACT: Ms. Mary Johnson, Energy Strategies 
Group, Sector Policies and Programs Division, (D243-01), Office of Air 
Quality Planning and Standards, U.S. Environmental Protection Agency, 
Research Triangle Park, North Carolina 27711; telephone number: (919) 
541-5025; Fax number (919) 541-5450; e-mail address: 
johnson.mary@epa.gov.

SUPPLEMENTARY INFORMATION: 

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    Outline. The information in this preamble is organized as follows:

I. General Information
    A. Does this action apply to me?
    B. What should I consider as I prepare my comments to EPA?
    C. Where can I get a copy of this document?
    D. When would a public hearing occur?
II. Background Information
    A. What is the statutory authority and regulatory approach for 
this proposed rule?
    B. What source categories are affected by the proposed 
standards?
    C. What is the relationship between this proposed rule and other 
related national emission standards?
    D. How did we gather information for this proposed rule?
    E. How are the area source boiler HAP addressed by this proposed 
rule?
III. Clarification of the Source Category List
IV. Summary of This Proposed Rule
    A. Do the proposed standards apply to my source?
    B. What is the affected source?
    C. When must I comply with the proposed standards?
    D. What are the proposed MACT and GACT standards?
    E. What are the Startup, Shutdown, and Malfunction (SSM) 
requirements?
    F. What are the proposed initial compliance requirements?
    G. What are the proposed continuous compliance requirements?
    H. What are the proposed notification, recordkeeping and 
reporting requirements?
    I. Submission of Emissions Test Results to EPA
V. Rationale of This Proposed Rule
    A. How did EPA determine which pollution sources would be 
regulated under this proposed rule?
    B. How did EPA determine the subcategories for this proposed 
rule?
    C. What surrogates are we using?
    D. How did EPA determine the proposed standards for existing 
units?
    1. MACT Analysis for Mercury From Coal-Fired Boilers and POM
    2. GACT Determination for Existing Area Source Boilers
    E. How did EPA determine the proposed standards for new units?
    1. MACT Analysis for Mercury From Coal-Fired Boilers and POM
    2. GACT Determination for New Area Source Boilers
    F. How did we select the compliance requirements?
    G. Alternative MACT Standards for Consideration
    H. How did we decide to exempt these area source categories from 
title V permitting requirements?
VI. Summary of the Impacts of This Proposed Rule
    A. What are the air impacts?
    B. What are the cost impacts?
    C. What are the economic impacts?
    D. What are the social costs and benefits of this proposed rule?
    E. What are the water and solid waste impacts?
    F. What are the energy impacts?
VII. Relationship of This Proposed Action to CAA Section 112(c)(6)
VIII. Statutory and Executive Order Review
    A. Executive Order 12866: Regulatory Planning and Review
    B. Paperwork Reduction Act
    C. Regulatory Flexibility Act (RFA)
    D. Unfunded Mandates Reform Act of 1995
    E. Executive Order 13132: Federalism
    F. Executive Order 13175: Consultation and Coordination With 
Indian Tribal Governments
    G. Executive Order 13045: Protection of Children From 
Environmental Health Risks and Safety Risks
    H. Executive Order 13211: Actions Concerning Regulations That 
Significantly Affect Energy Supply, Distribution, or Use
    I. National Technology Transfer and Advancement Act
    J. Executive Order 12898: Federal Actions To Address 
Environmental Justice in Minority Populations and Low-Income 
Populations

I. General Information

A. Does this action apply to me?

    The regulated categories and entities potentially affected by the 
proposed standards include:

------------------------------------------------------------------------
                                                   Examples of regulated
           Category              NAICS Code \1\          entities
------------------------------------------------------------------------
Any area source facility using               321  Wood product
 a boiler as defined in this                       manufacturing.
 proposed rule.
                                              11  Agriculture,
                                                   greenhouses.
                                             311  Food manufacturing.
                                             327  Nonmetallic mineral
                                                   product
                                                   manufacturing.
                                             422  Wholesale trade,
                                                   nondurable goods.
                                             531  Real estate.
                                             611  Educational services.
                                             813  Religious, civic,
                                                   professional, and
                                                   similar
                                                   organizations.
                                              92  Public administration.
                                             722  Food services and
                                                   drinking places.
                                              62  Health care and social
                                                   assistance.
------------------------------------------------------------------------
\1\ North American Industry Classification System.

    This table is not intended to be exhaustive, but rather provides a 
guide for readers regarding entities likely to be affected by this 
action. To determine whether your facility, company, business, 
organization, etc., would be regulated by this action, you should 
examine the applicability criteria in 40 CFR 63.11193 of subpart JJJJJJ 
(National Emission Standards for Hazardous Air Pollutants for 
Industrial, Commercial, and Institutional Boilers Area Sources). If you 
have any questions regarding the applicability of this action to a 
particular entity, consult either the delegated regulatory authority 
for the entity or your EPA regional representative as listed in 40 CFR 
63.13 of subpart A (General Provisions).

B. What should I consider as I prepare my comments to EPA?

    Do not submit information containing CBI to EPA through https://www.regulations.gov or e-mail. Send or deliver information identified 
as CBI only to the following address: Roberto Morales, OAQPS Document 
Control Officer (C404-02), Office of Air Quality Planning and 
Standards, U.S. Environmental Protection Agency, Research Triangle 
Park, North Carolina 27711, Attention: Docket ID EPA-HQ-OAR-2006-0790. 
Clearly mark the part or all of the information that you claim to be 
CBI. For CBI information in a disk or CD-ROM that you mail to EPA, mark 
the outside of the disk or CD-ROM as CBI and then identify 
electronically within the disk or CD-ROM the specific information that 
is claimed as CBI. In addition to one complete version of the comment 
that includes information claimed as CBI, a copy of the comment that 
does not contain the information claimed as CBI must be submitted for 
inclusion in the public docket. Information so marked will not be 
disclosed except in accordance with procedures set forth in 40 CFR part 
2.

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C. Where can I get a copy of this document?

    In addition to being available in the docket, an electronic copy of 
this proposed action will also be available on the Worldwide Web (WWW) 
through the Technology Transfer Network (TTN). Following signature, a 
copy of the proposed action will be posted on the TTN's policy and 
guidance page for newly proposed or promulgated rules at the following 
address: https://www.epa.gov/ttn/oarpg/. The TTN provides information 
and technology exchange in various areas of air pollution control.

D. When would a public hearing occur?

    We will hold a public hearing concerning this proposed rule on June 
21, 2010. Persons interested in presenting oral testimony at the 
hearing should contact Ms. Pamela Garrett, Energy Strategies Group, at 
(919) 541-7966 by June 14, 2010. The public hearing will be held in the 
Washington, DC area at a location and time that will be posted at the 
following Web site: https://www.epa.gov/airquality/combustion. Please 
refer to this Web site to confirm the date of the public hearing as 
well. If no one requests to speak at the public hearing by June 14, 
2010 then the public hearing will be cancelled and a notification of 
cancellation posted on the following Web site: https://www.epa.gov/airquality/combustion.

II. Background Information

A. What is the statutory authority and regulatory approach for this 
proposed rule?

    Section 112(d) of the Clean Air Act (CAA) requires us to establish 
NESHAP for both major and area sources of hazardous air pollutants 
(HAP) that are listed for regulation under CAA section 112(c). A major 
source emits or has the potential to emit 10 tons per year (tpy) or 
more of any single HAP or 25 tpy or more of any combination of HAP. An 
area source is a HAP-emitting stationary source that is not a major 
source.
    CAA section 112(k)(3)(B) calls for EPA to identify at least 30 HAP 
which, as the result of emissions from area sources, pose the greatest 
threat to public health in the largest number of urban areas. EPA 
implemented this provision in 1999 in the Integrated Urban Air Toxics 
Strategy (Strategy), (64 FR 38715, July 19, 1999). Specifically, in the 
Strategy, EPA identified 30 HAP that pose the greatest potential health 
threat in urban areas, and these HAP are referred to as the ``30 urban 
HAP.'' CAA section 112(c)(3) requires EPA to list sufficient categories 
or subcategories of area sources to ensure that area sources 
representing 90 percent of the emissions of the 30 urban HAP are 
subject to regulation. A primary goal of the Strategy is to achieve a 
75 percent reduction in cancer incidence attributable to HAP emitted 
from stationary sources.
    Under CAA section 112(d)(5), we may elect to promulgate standards 
or requirements for area sources ``which provide for the use of 
generally available control technologies or management practices 
(`GACT') by such sources to reduce emissions of hazardous air 
pollutants.'' Additional information on GACT is found in the Senate 
report on the legislation (Senate Report Number 101-228, December 20, 
1989), which describes GACT as:

    * * * methods, practices and techniques which are commercially 
available and appropriate for application by the sources in the 
category considering economic impacts and the technical capabilities 
of the firms to operate and maintain the emissions control systems.

    Consistent with the legislative history, we can consider costs and 
economic impacts in determining GACT, which is particularly important 
when developing regulations for source categories that may have many 
small businesses such as these.
    Determining what constitutes GACT involves considering the control 
technologies and management practices that are generally available to 
the area sources in the source category. We also consider the standards 
applicable to major sources in the analogous source category to 
determine if the control technologies and management practices are 
transferable and generally available to area sources. In appropriate 
circumstances, we may also consider technologies and practices at area 
and major sources in similar categories to determine whether such 
technologies and practices could be considered generally available for 
the area source categories at issue. Finally, as noted above, in 
determining GACT for a particular area source category, we consider the 
costs and economic impacts of available control technologies and 
management practices on that category.
    While GACT may be a basis for standards for most types of HAP 
emitted from area sources, CAA section 112(c)(6) requires that EPA list 
categories and subcategories of sources assuring that sources 
accounting for not less than 90 percent of the aggregate emissions of 
each of the seven specified hazardous air pollutants (HAP) are subject 
to standards under section 112(d)(2) or (d)(4). The seven HAP specified 
in section 112(c)(6) are as follows: alkylated lead compounds, 
polycyclic organic matter, hexachlorobenzene, mercury, polychlorinated 
biphenyls, 2,3,7,9-tetrachlorodibenzofurans, and 2,3,7,8-
tetrachloridibenzo-p-dioxin.
    The CAA section 112(c)(6) list of source categories currently 
includes industrial coal combustion, industrial oil combustion, 
industrial wood combustion, commercial coal combustion, commercial oil 
combustion, and commercial wood combustion. See 63 FR 17849. We listed 
these source categories under CAA section 112(c)(6) based on the source 
categories' contribution of mercury and polycyclic organic matter 
(POM). In the documentation for the CAA section 112(c)(6) listing, the 
commercial fuel combustion categories included institutional fuel 
combustion (see ``1990 Emissions Inventory of Section 112(c)(6) 
Pollutants, Final Report,'' April 1998). As discussed in greater detail 
below, we re-examine the emission inventory and the need to address 
categories under CAA section 112(c)(6) during the rule development 
process. Based on this re-examination, we now believe we will only need 
to address the coal-fueled portion of these categories under CAA 
section 112(c)(6).
    With this proposed rule and the major source boilers rule, we 
currently believe that we have subjected to regulation or proposed to 
regulate at least 90 percent of the 1990 section 112(c)(6) emissions 
inventory for mercury. Coal-fired area source boilers represent 
approximately 4.3 percent of the 1990 section 112(c)(6) emissions 
inventory for mercury. In contrast, biomass- and oil-fired boilers 
represent approximately 0.34 percent. Consequently, we are proposing to 
regulate coal-fired boilers under MACT because we need these sources to 
meet the 90 percent requirement for mercury in section 112(c)(6). We 
are proposing to regulate biomass-fired and oil-fired types of boilers 
under GACT to meet the 90 percent requirement for mercury in section 
112(c)(3).
    We solicit comment on whether we should nevertheless establish 
MACT-based mercury emission standards for all boilers in this category. 
In your comments, please explain the basis for your position and 
provide any supporting documentation.
    The ``maximum achievable control technology'' or ``MACT'' 
regulation required by CAA section 112(d)(2) or (4) can be based on the 
emissions reductions achievable through application of measures, 
processes, methods, systems, or techniques including, but not limited 
to: (1)

[[Page 31899]]

Reducing the volume of, or eliminating emissions of, such pollutants 
through process changes, substitutions of materials, or other 
modifications; (2) enclosing systems or processes to eliminate 
emissions; (3) collecting, capturing, or treating such pollutants when 
released from a process, stack, storage or fugitive emission point; (4) 
design, equipment, work practices, or operational standards as provided 
in CAA section 112(h); or (5) a combination of the above.
    The MACT floor is the minimum control level allowed for NESHAP and 
is defined under CAA section 112(d)(3). For new sources, MACT based 
standards cannot be less stringent than the emission control achieved 
in practice by the best-controlled similar source, as determined by the 
Administrator. The MACT based standards for existing sources can be 
less stringent than standards for new sources, but they cannot be less 
stringent than the average emission limitation achieved by the best 
performing 12 percent of existing sources in the category or 
subcategory (for which the Administrator has emission information) for 
source categories and subcategories with 30 or more sources, or the 
best performing 5 sources for categories and subcategories with fewer 
than 30 sources (CAA section 112(d)(3)(A) and (B)).
    Although emission standards are often structured in terms of 
numerical emissions limits, alternative approaches are sometimes 
necessary and authorized pursuant to CAA section 112. For example, in 
some cases, physically measuring emissions from a source may be not 
practicable due to technological and economic limitations. CAA section 
112(h) authorizes the Administrator to promulgate a design, equipment, 
work practice, or operational standard, or combination thereof, 
consistent with the provisions of CAA sections 112(d) or (f), in those 
cases where, in the judgment of the Administrator, it is not feasible 
to prescribe or enforce an emission standard. CAA section 112(h)(2) 
provides that the phrase ``not feasible to prescribe or enforce an 
emission standard'' includes the situation in which the Administrator 
determines that * * * the application of measurement methodology to a 
particular class of sources is not practicable due to technological and 
economic limitations.
    As noted above, we listed industrial coal combustion, industrial 
oil combustion, industrial wood combustion, commercial coal combustion, 
commercial oil combustion, and commercial wood combustion under CAA 
section 112(c)(6) based on the source categories' contribution of 
mercury and polycyclic organic matter (POM). We listed these same 
categories under section 112(c)(3) for their contribution of mercury, 
arsenic, beryllium, cadmium, lead, chromium, manganese, nickel, 
polycyclic organic matter (POM) (as 7-PAH (polynuclear aromatic 
hydrocarbons)), ethylene dioxide, and polychlorinated biphenyls (PCB).
    We have developed proposed standards to reflect the application of 
MACT for mercury from coal-fired area source boilers and POM from all 
area source boilers under section 112(c)(6) and have applied GACT for 
the other pollutants noted above.

B. What source categories are affected by the proposed standards?

    The source categories affected by the proposed standards are 
industrial boilers and commercial and institutional boilers. Both 
source categories were included in the area source list published on 
July 19, 1999 (64 FR 38721). The inclusion of these two source 
categories on the CAA section 112(c)(3) area source category list is 
based on 1990 emissions data, as EPA used 1990 as the baseline year for 
that listing. We describe above the pollutants that formed the basis of 
the listings.
    This proposed rule would apply to all existing and new industrial 
boilers, institutional boilers, and commercial boilers located at area 
sources. The industrial boiler source category includes boilers used in 
manufacturing, processing, mining, refining, or any other industry. The 
commercial boiler source category includes boilers used in commercial 
establishments such as stores/malls, laundries, apartments, 
restaurants, and hotels/motels. The institutional boiler source 
category includes boilers used in medical centers (e.g., hospitals, 
clinics, nursing homes), educational and religious facilities (e.g., 
schools, universities, churches), and municipal buildings (e.g., 
courthouses, prisons).
    Boiler means an enclosed combustion device having the primary 
purpose of recovering thermal energy in the form of steam or hot water.

C. What is the relationship between this proposed rule and other 
related national emission standards?

    This proposed rule regulates industrial boilers and institutional/
commercial boilers that are area sources of HAP. Today, in a parallel 
action, a NESHAP for industrial, commercial, and institutional boilers 
located at major sources is being proposed reflecting application of 
MACT. The major source NESHAP regulates emissions of particulate matter 
(PM) (as a surrogate for non-mercury metals), mercury, hydrogen 
chloride (HCl)(as a surrogate for acid gases), dioxins/furans, and 
carbon monoxide (CO) (as a surrogate for non-dioxin organic HAP) from 
existing and new major source boilers.
    This proposed rule covers boilers located at area source 
facilities. In addition to the major source MACT for boilers being 
issued today and this rule, the Agency is also issuing emission 
standards today pursuant to CAA section 129 for commercial and 
industrial solid waste incineration units. In a parallel action, EPA is 
proposing a solid waste definition rulemaking pursuant to Subtitle D of 
RCRA. That action is relevant to this proceeding because if an 
industrial, commercial, or institutional unit located at an area source 
combusts secondary materials that are ``solid waste,'' as that term is 
defined by the Administrator under RCRA, those units would be subject 
to section 129 of the CAA, not section 112.
    As background, in 2007, the United States Court of Appeals for the 
District of Columbia Circuit (DC Circuit) vacated the CISWI Definitions 
Rule, which EPA issued pursuant to CAA section 129. The court found 
that the definitions in that rule were inconsistent with the CAA. 
Specifically, the Court held that the term ``solid waste incineration 
unit'' in CAA Section 129(g)(1) ``unambiguously include[s] among the 
incineration units subject to its standards any facility that combusts 
any commercial or industrial solid waste material at all--subject to 
the four statutory exceptions identified [in CAA Section 129(g)(1)].'' 
NRDC v. EPA, 489 F.3d at 1257-58.
    Based on the information available to the Agency, we believe that 
the boilers that are subject to this area source rule combust coal, 
oil, and biomass. EPA does not believe that the boilers subject to this 
rule combust any non-hazardous secondary materials, whether they are 
considered a solid waste or not. If you are aware of such materials 
being combusted at these boilers, please provide specific information 
as to the type of secondary material being combusted and at what type 
of facilities and in what quantities. If the final form of the solid 
waste definition results in any secondary materials being considered 
solid waste it will be important to know whether units are burning 
those materials, because that would result in those units becoming 
incinerators subject to regulation under

[[Page 31900]]

section 129 and no longer being considered boilers.
    There is also another CAA regulation that is relevant in that they 
apply to some of the affected sources in this rule. For example, in 
1986, EPA codified new source performance standards (NSPS) for 
industrial, commercial, and institutional boilers (40 CFR part 60, 
subparts Db and Dc) and revised portions of them in 1999 and 2006. The 
NSPS regulates emissions of PM, sulfur dioxide (SO2), and 
nitrogen oxides from boilers constructed after June 19, 1984. Sources 
subject to the NSPS that are located at area source facilities are also 
subject to this proposed rule because this proposed rule regulates HAP. 
In developing this proposal, we have streamlined the monitoring and 
recordkeeping requirements to avoid duplicating requirements in the 
NSPS.

D. How did we gather information for this proposed rule?

    We gathered information for this proposed rule from States' boiler 
inspection lists, company Web sites, published literature, State 
permits, current State and Federal regulations, and from an Information 
Collection Request (ICR) conducted for the major source NESHAP.
    We developed an initial nationwide population of area source 
boilers based on boiler inspector databases from 13 States. The boiler 
inspector databases include steam boilers that are required to be 
inspected for safety or insurance purposes. We classified the area 
source boilers to NAICS codes based on the ``name'' of the facility at 
which the boiler was located. However, many of the boilers in the 
boiler inspector database could not be readily assigned to an NAICS 
code.
    We reviewed State and other Federal regulations that apply to the 
area sources in the source categories for information concerning 
existing HAP emission control approaches. For example, as noted above, 
the NSPS for small industrial, commercial, and institutional boilers in 
40 CFR part 60, subpart Dc apply to boilers at some area sources. 
Similarly, permit requirements established by the Ohio, Illinois, 
Vermont, New Hampshire, and Maine air regulatory agencies apply to some 
area sources. We also reviewed standards for boilers at major sources 
that would be appropriate for and transferable to boilers at area 
sources. For example, we determined that management practices, such as, 
annual tune-ups and operator training applicable to major source 
boilers are equally feasible for boilers at area sources.

E. How are the area source boiler HAP addressed by this proposed rule?

    As explained above, industrial coal combustion, industrial oil 
combustion, industrial wood combustion, commercial coal combustion, 
commercial oil combustion, and commercial wood combustion are listed 
under CAA section 112(c)(6) due to contributions of mercury and POM and 
these same categories are listed under CAA section 112(c)(3) for their 
contribution of mercury, arsenic, beryllium, cadmium, lead, chromium, 
manganese, nickel, POM, ethylene dioxide, and PCB.
    With respect to the 112(c)(3) pollutants, we used surrogates 
because, as explained below, it was not practical to establish 
individual standards for each specific HAP. We grouped the 112(c)(3) 
pollutants, which formed the basis for the listing of these two source 
categories, into three common groupings: mercury, non-mercury metallic 
HAP (arsenic, beryllium, cadmium, chromium, lead, manganese, and 
nickel), and organic HAP (POM, ethylene dichloride, and PCB). In 
general, the pollutants within each group have similar characteristics 
and can be controlled with the same techniques.
    For the non-mercury metallic HAP, we selected PM as a surrogate. 
The inherent variability and unpredictability of the non-mercury metal 
HAP compositions and amounts in fuel has a material effect on the 
composition and amount of non-mercury metal HAP in the emissions from 
the boiler. As a result, establishing individual numerical emissions 
limits for each non-mercury HAP metal species is difficult given the 
level of uncertainty about the individual non-mercury metal HAP 
compositions of the fuels that will be combusted. An emission 
characteristic common to all boilers is that the non-mercury metal HAP 
are a component of the PM contained in the fly ash emitted from the 
boiler. A sufficient correlation exists between PM and non-mercury 
metallic HAP to rely on PM as a surrogate for these HAP and for their 
control. Therefore, the same control techniques that would be used to 
control the fly-ash PM will control non-mercury metallic HAP. Emissions 
limits established to achieve control of PM will also achieve control 
of non-mercury metal HAP. Furthermore, establishing separate standards 
for each individual HAP would impose costly and significantly more 
complex compliance and monitoring requirements and achieve little, if 
any, HAP emissions reductions beyond what would be achieved using the 
surrogate pollutant approach.
    For organic HAP, we selected CO as a surrogate for organic 
compounds, including POM, emitted from the various fuels burned in 
boilers. The presence of CO is an indicator of incomplete combustion. A 
high level of CO in emissions is an indicator of incomplete combustion 
and, thus, a potential indication of elevated organic HAP emissions. 
Monitoring equipment for CO is readily available, which is not the case 
for organic HAP. Also, it is significantly easier and less expensive to 
measure and monitor CO emissions than to measure and monitor emissions 
of each individual organic HAP. We considered other surrogates, such as 
total hydrocarbon (THC), but lacked data on emissions and permit limits 
for area source boilers. Therefore, using CO as a surrogate for organic 
urban HAP is a reasonable approach because minimizing CO emissions will 
result in minimizing organic urban HAP emissions.
    Based on these considerations, we are proposing GACT standards for 
PM (as a surrogate for the individual urban metal HAP), CO (as a 
surrogate pollutant for the individual urban organic HAP), and mercury 
from biomass-fired and oil-fired boilers. We are proposing MACT 
standards for mercury from coal-fired boilers and for POM from all 
boilers.

III. Clarification of the Source Category List

    The Industrial Boilers and the Institutional/Commercial Boilers 
area source categories were listed under section 112(c)(3) of the CAA. 
EPA needs to establish emission standards for area source boilers for 
the following urban HAP in order to meet the section 112(c)(3) 90 
percent requirement for these HAP: mercury, arsenic, beryllium, 
cadmium, lead, chromium, manganese, nickel, POM (as 7-PAH), ethylene 
dioxide, and PCB. Natural gas-fired area source boilers do not emit any 
of the urban HAP identified above. Therefore, regulation of gas-fired 
area source boilers is not necessary to meet the 90 percent requirement 
under section 112(c)(3) for these HAP. For the reason stated above, 
pursuant to section 112(c)(3) of the CAA, we are proposing emission 
standards for the above mentioned HAP for area source boilers fired by 
coal, oil, and wood, but not standards for boilers fired by natural 
gas.

[[Page 31901]]

IV. Summary of This Proposed Rule

A. Do the proposed standards apply to my source?

    This proposed rule applies to you if you own or operate a boiler 
combusting coal, biomass, or oil located at an area source. The 
standards do not apply to boilers that are subject to another standard 
under 40 CFR part 63 or to a standard developed under CAA section 129.
    This proposed rule applies to you if you own or operate a boiler 
combusting natural gas, located at an area source, which switches to 
combusting coal, biomass, or oil after the date of proposal.

B. What is the affected source?

    The affected source is the collection of all existing boilers 
within a subcategory located at an area source facility or each new 
boiler located at an area source facility.

C. When must I comply with the proposed standards?

    The owner or operator of an existing source would be required to 
comply with the rule no later than 3 years after the date of 
publication of the final rule in the Federal Register. The owner or 
operator of a new source would be required to comply upon the date of 
publication of the final rule in the Federal Register or startup of the 
facility, whichever is later.

D. What are the proposed MACT and GACT standards?

    Emission standards expressed in the form of emission limits are 
being proposed for new and existing area source boilers. The proposed 
MACT emission limits for mercury and CO (as a surrogate for POM) are 
presented, along with the proposed GACT standards for PM (as a 
surrogate for urban metals), in Table 1 of this preamble.

                                Table 1--Emission Limits for Area Source Boilers
                              [Pounds per million British thermal units heat input]
----------------------------------------------------------------------------------------------------------------
                                                          Particulate                          Carbon monoxide
             Source                   Subcategory         matter  (PM)         Mercury            (CO) (ppm)
----------------------------------------------------------------------------------------------------------------
New Boiler......................  Coal...............               0.03            3.0E-06  310 (@ 7% oxygen).
                                  Biomass............               0.03  .................  100 (@ 7% oxygen).
                                  Oil................               0.03  .................  1 (@ 3% oxygen).
Existing Boiler.................  Coal...............  .................            3.0E-06  310 (@ 7% oxygen).
                                  Biomass............  .................  .................  160 (@ 7% oxygen).
                                  Oil................  .................  .................  2 (@ 3% oxygen).
----------------------------------------------------------------------------------------------------------------

    The emission limits for existing area source boilers are only 
applicable to area source boilers that have a designed heat input 
capacity of 10 million British thermal units per hour (MMBtu/h) or 
greater. If your boiler burns at least 10 percent coal on a total fuel 
annual heat input basis, the boiler is in the coal fuel subcategory. If 
your boiler burns biomass or biomass in combination with a liquid or 
gaseous fuel, the unit is in the biomass subcategory. If your boiler 
burns oil, or oil in combination with a gaseous fuel, the unit is in 
the oil subcategory, except if the unit burns oil only during periods 
of gas curtailment.
    As allowed under CAA section 112(h), a work practice standard is 
being proposed for existing area source boilers that are units with 
designed heat input capacity of less than 10 MMBtu/h. The work practice 
standard for existing small area source boilers requires the 
implementation of a tune-up program.
    An additional standard is being proposed for existing area source 
facilities having an affected boiler with a designed heat input 
capacity of 10 MMBtu/h or greater that requires the performance of an 
energy assessment, by qualified personnel, on the boiler and the 
facility to identify cost-effective energy conservation measures.

E. What are the Startup, Shutdown, and Malfunction (SSM) requirements?

    The United States Court of Appeals for the District of Columbia 
Circuit vacated portions of two provisions in EPA's CAA section 112 
regulations governing the emissions of HAP during periods of startup, 
shutdown, and malfunction (SSM). Sierra Club v. EPA, 551 F.3d 1019 
(D.C. Cir. 2008), cert. denied, 2010 U.S. LEXIS 2265 (2010). 
Specifically, the Court vacated the SSM exemption contained in 40 CFR 
63.6(f)(1) and 40 CFR 63.6(h)(1), that are part of a regulation, 
commonly referred to as the ``General Provisions Rule,'' that EPA 
promulgated under section 112 of the CAA. When incorporated into CAA 
Section 112(d) regulations for specific source categories, these two 
provisions exempt sources from the requirement to comply with the 
otherwise applicable CAA section 112(d) emission standard during 
periods of SSM.
    Consistent with Sierra Club v. EPA, EPA has established standards 
in this rule that apply at all times. EPA has attempted to ensure that 
we have not incorporated into proposed regulatory language any 
provisions that are inappropriate, unnecessary, or redundant in the 
absence of an SSM exemption. We are specifically seeking comment on 
whether there are any such provisions that we have inadvertently 
incorporated or overlooked. We also request comment on whether there 
are additional provisions that should be added to regulatory text in 
light of the absence of an SSM exemption and provisions related to the 
SSM exemption (such as the SSM plan requirement and SSM recordkeeping 
and reporting provisions).
    In establishing the standards in this rule, EPA has taken into 
account startup and shutdown periods and, for the reasons explained 
below, has not established different standards for those periods. The 
standards that we are proposing are daily or monthly averages. Based 
upon continuous emission monitoring data, obtained as part of the 
information collection effort for the major source boiler and process 
heater rulemaking, which included periods of startup and shutdown, over 
long averaging periods, startups and shutdowns will not affect the 
achievability of the standard. Boilers, especially solid fuel-fired 
boilers, do not normally startup and shutdown more than once per day. 
Thus, we are not establishing a separate emission standard for these 
periods because startup and shutdown are part of their routine 
operations and, therefore, are already addressed by the standards.
    Periods of startup, normal operations, and shutdown are all 
predictable and routine aspects of a source's operations. However, by 
contrast, malfunction is

[[Page 31902]]

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). EPA has determined that malfunctions should not be 
viewed as a distinct operating mode and, therefore, any emissions that 
occur at such times do not need to be factored into development of CAA 
section 112(d) standards, which, once promulgated, apply at all times. 
It is reasonable to interpret section 112(d) as not requiring EPA to 
account for malfunctions in setting emissions standards. For example, 
we note that CAA section 112 uses the concept of ``best performing'' 
sources in defining MACT, the level of stringency that major source 
standards must meet. Applying the concept of ``best performing'' to a 
source that is malfunctioning presents significant difficulties. The 
goal of best performing sources is to operate in such a way as to avoid 
malfunctions of their units. Similarly, although standards for area 
sources are generally not required to be set based on ``best 
performers,'' we believe that what is ``generally available'' should 
not be based on periods in which there is a ``failure to operate.''
    Moreover, even if malfunctions were considered a distinct operating 
mode, we believe it would be impracticable to take malfunctions into 
account in setting CAA section 112(d) standards for area source 
boilers. As noted above, by definition, malfunctions are sudden and 
unexpected events and it would be difficult to set a standard that 
takes into account the myriad different types of malfunctions that can 
occur across all sources in the category. Moreover, malfunctions can 
vary in frequency, degree, and duration, further complicating standard 
setting.
    In the event that a source fails to comply with the applicable CAA 
section 112(d) standards as a result of a malfunction event, EPA would 
determine an appropriate response based on, among other things, the 
good faith efforts of the source to minimize emissions during 
malfunction periods, including preventative and corrective actions, as 
well as root cause analyses to ascertain and rectify excess emissions. 
EPA would also consider whether the source's failure to comply with the 
CAA section 112(d) standard was, in fact, ``sudden, infrequent, not 
reasonably preventable'' and was not instead ``caused in part by poor 
maintenance or careless operation.'' 40 CFR 63.2 (definition of 
malfunction).

F. What are the proposed initial compliance requirements?

    For new and existing area source boilers with applicable emission 
limits, we are proposing that you must conduct initial stack tests or 
fuel analysis (for mercury) to determine compliance with the PM, 
mercury, and CO emission limits.
    As part of the initial compliance demonstration, we are proposing 
that you must monitor specified operating parameters during the initial 
performance tests that demonstrate compliance with the PM and mercury 
emission limits for area source boilers with wet or dry scrubbers. The 
test average establishes your site-specific operating levels.
    For owners or operators of existing area source boilers having a 
heat input capacity of less than 10 MMBtu/h, we are proposing that you 
must submit to the delegated authority or EPA, as appropriate, 
documentation that a tune-up was conducted.
    For owners or operators of existing area source facilities having a 
boiler with a heat input capacity of 10 MMBtu/h or greater and subject 
to this rule, we are proposing that you submit to the delegated 
authority or EPA, as appropriate, documentation that the energy 
assessment was performed and the cost-effective energy conservation 
measures identified.

G. What are the proposed continuous compliance requirements?

    If you demonstrate initial compliance with the emission limits by 
performance (stack) tests, we are proposing that you conduct stack 
tests on an annual basis. Furthermore, to demonstrate continuous 
compliance with the PM and mercury emission limits, we are proposing 
that you must monitor and comply with the applicable site-specific 
operating limits.
    For area source boilers without wet scrubbers that must comply with 
the PM and mercury emission limits, we are proposing that you must 
continuously monitor opacity and maintain the opacity at or below ten 
percent (daily block average). Or, if the unit is controlled with a 
fabric filter, instead of continuously monitoring opacity, we are 
proposing that the fabric filter may be continuously operated such that 
the bag leak detection system alarm does not sound more than 5 percent 
of the operating time during any 6-month period.
    For boilers with wet scrubbers that must comply with the PM and 
mercury emission limits, we are proposing that you must monitor 
pressure drop and liquid flow rate of the scrubber and maintain the 
daily block averages at or above the minimum operating limits 
established during the performance test.
    If you elected to demonstrate initial compliance with the mercury 
emission limit by fuel analysis, we are proposing that you conduct a 
monthly fuel analysis and maintain the annual average at or below the 
limit indicated in Table 1 of this preamble.
    For boilers that demonstrate compliance with the PM and mercury 
emission limits by performance (stack) tests, we propose that you must 
maintain monthly fuel records that demonstrate that you burned no new 
fuel type or new mixture (monthly average) as set during the 
performance test. If you plan to burn a new fuel type or new mixture 
than what was burned during the initial performance test, then we are 
proposing that you must conduct a new performance test to demonstrate 
continuous compliance with the PM emission limit and mercury emission 
limit.
    For boilers with heat input capacities equal to or greater than 100 
MMBtu/hr, we propose that you must continuously monitor CO and maintain 
the daily average CO emissions at or below the limits indicated in 
Table 1 to demonstrate compliance with the CO emission limits at all 
times.

H. What are the proposed notification, recordkeeping and reporting 
requirements?

    All new and existing sources would be required to comply with some 
requirements of the General Provisions (40 CFR part 63, subpart A), 
which are identified in Table 6 of this proposed rule. The General 
Provisions include specific requirements for notifications, 
recordkeeping, and reporting. If performance tests are required under 
this proposed rule, then the notification and reporting requirements 
for performance tests in the General Provisions would also apply.
    Each owner or operator would be required to submit a notification 
of compliance status report, as required by 40 CFR 63.9(h) of the 
General Provisions. This proposed rule requires the owner or operator 
to include in the notification of compliance status report 
certifications of compliance with rule requirements.
    Semiannual compliance reports, as required by 40 CFR 63.10(e)(3) of 
subpart A, would be required only for semiannual reporting periods when 
a deviation from any of the requirements in the rule occurred, or any 
process changes occurred and compliance certifications were 
reevaluated.

[[Page 31903]]

    This proposed rule would require records to demonstrate compliance 
with each emission limit, work practice standard, or management 
practice. These recordkeeping requirements are specified directly in 
the General Provisions to 40 CFR part 63.
    Records for applicable management practices must be maintained. 
Specifically, the owner or operator must keep records of the dates and 
the results of each boiler tune-up.
    Records of either continuously monitored parameter data for a 
control device if a device is used to control the emissions or 
continuous emission monitoring system (CEMS) data would be required.
    Each owner and operator would be required to keep the following 
records:
    (1) All reports and notifications submitted to comply with the 
rule;
    (2) Continuous monitoring data as required in the rule;
    (3) Each instance in which you did not meet each emission limit, 
work/management practice, and operating limit (i.e., deviations from 
the rule);
    (4) Monthly fuel use by each boiler including a description of the 
type(s) of fuel(s) burned, amount of each fuel type burned, and units 
of measure;
    (5) A copy of the results of all performance tests, energy 
assessments, opacity observations, performance evaluations, or other 
compliance demonstrations conducted to demonstrate initial or 
continuous compliance with the rule; and
    (6) A copy of your site-specific monitoring plan developed for the 
rule, if applicable.
    Typically, records would be retained for at least 5 years. In 
addition, monitoring plans, operating and maintenance plans, and other 
plans would be updated as necessary and kept for as long as they are 
still current.

I. Submission of Emissions Test Results to EPA

    Compliance test data are necessary for many purposes including 
compliance determinations, development of emission factors, and 
determining annual emission rates. EPA has found it burdensome and time 
consuming to collect emission test data because of varied locations for 
data storage and varied data storage methods.
    One improvement that has occurred in recent years is the 
availability of stack test reports in electronic format as a 
replacement for bulky paper copies.
    In this action, we are taking a step to improve data accessibility 
for stack tests (and in the future continuous monitoring data). Boiler 
area sources would be required to submit to WebFIRE (an EPA electronic 
database) an electronic copy of stack test reports as well as process 
data. Data entry requires only access to the Internet and is expected 
to be completed by the stack testing company as part of the work that 
it is contracted to perform.
    Please note that the proposed requirement to submit source test 
data electronically to EPA would not require any additional performance 
testing. In addition, when a facility submits performance test data to 
WebFIRE, there would be no additional requirements for data 
compilation; instead, we believe industry would greatly benefit from 
improved emissions factors, fewer information requests, and better 
regulation development as discussed below. Because the information that 
would be reported is already required in the existing test methods and 
is necessary to evaluate the conformance to the test methods, 
facilities would already be collecting and compiling these data. One 
major advantage of submitting source test data through the Electronic 
Reporting Tool (ERT), which was developed with input from stack testing 
companies (who already collect and compile performance test data 
electronically), is that it would provide a standardized method to 
compile and store all the documentation required by this proposed rule. 
Another important benefit of submitting these data to EPA at the time 
the source test is conducted is that these data should reduce the 
effort involved in data collection activities in the future for these 
source categories. This results in a reduced burden on both affected 
facilities (in terms of reduced manpower to respond to data collection 
requests) and EPA (in terms of preparing and distributing data 
collection requests). Finally, another benefit of submitting these data 
to WebFIRE electronically is that these data will greatly improve the 
overall quality of the existing and new emissions factors by 
supplementing the pool of emissions test data upon which emissions 
factors are based and by ensuring that data are more representative of 
current industry operational procedures. A common complaint we hear 
from industry and regulators is that emissions factors are out-dated or 
not representative of a particular source category. Receiving recent 
performance test results would ensure that emissions factors are 
updated and more accurate. In summary, receiving these test data 
already collected for other purposes and using them in the emissions 
factors development program will save industry, State/local/tribal 
agencies, and EPA time and money.
    As mentioned earlier, the electronic data base that will be used is 
EPA's WebFIRE, which is a Web site accessible through EPA's TTN 
(technology transfer network). The WebFIRE Web site was constructed to 
store emissions test data for use in developing emission factors. A 
description of the WebFIRE data base can be found at https://cfpub.epa.gov/oarweb/index.cfm?action=fire.main. The ERT will be able 
to transmit the electronic report through EPA's Central Data Exchange 
(CDX) network for storage in the WebFIRE data base. Although ERT is not 
the only electronic interface that can be used to submit source test 
data to the CDX for entry into WebFIRE, it makes submittal of data very 
straightforward and easy. A description of the ERT can be found at 
https://www.epa.gov/ttn/chief/ert/ert_tool.html.
    The ERT can be used to document the conducting of stack tests data 
for various pollutants including PM, mercury, dioxin/furan, and HCl. 
Presently, the ERT does not accept opacity data or CEMS data.
    EPA specifically requests comment on the utility of this electronic 
reporting requirement and the burden that owners and operators of 
boiler area source facilities estimate would be associated with this 
requirement.

V. Rationale of This Proposed Rule

A. How did EPA determine which pollution sources would be regulated 
under this proposed rule?

    This proposed rule regulates industrial boilers (fired by coal, 
biomass, or oil) and institutional and commercial boilers (fired by 
coal, biomass, or oil) that are located at area sources of HAP.
    Boilers that are used specifically for research and development are 
not regulated. However, boilers that only provide steam to a process or 
for heating at a research and development facility are still subject to 
this proposed rule.

B. How did EPA determine the subcategories for this proposed rule?

    The CAA allows EPA to divide source categories into subcategories 
when differences between given types of units lead to corresponding 
differences in the nature of emissions or the technical feasibility of 
applying emission control techniques. The design, operating, and 
emissions information that EPA reviewed during the major source 
rulemaking indicates the need to subcategorize boilers based on the 
boiler type.

[[Page 31904]]

    Boiler systems are designed for specific fuel types (e.g., coal, 
biomass, or oil) and will encounter problems if a fuel with 
characteristics other than those originally specified is fired. Most 
boilers can only achieve full load on the fuel or fuels for which they 
were specifically designed. Changes to the fuel type would often 
require extensive changes to the fuel handling and feeding system. 
Additionally, the burners and combustion chamber would need to be 
redesigned and modified to handle different fuel types and account for 
increases or decreases in the fuel volume and shape. In some cases, the 
changes may reduce the capacity and efficiency of the boiler. An 
additional effect of these changes would be extensive retrofit costs.
    Emissions from boilers burning coal, biomass, and oil will also 
differ. Boilers emit a number of urban HAP. In general, HAP formation 
is dependent upon the composition of the fuel. The combustion quality 
and temperature also play an important role. The fuel dependent urban 
HAP emissions from boilers are metals, including mercury. These fuel 
dependent HAP emissions generally can be controlled by either changing 
the fuel property before combustion or by removing the HAP from the 
flue gas after combustion. Organic HAP, on the other hand, are formed 
from incomplete combustion and are much less influenced by the 
characteristics of the fuel being burned. The degree of combustion may 
be greatly influenced by three general factors: time, turbulence, and 
temperature. These factors are a function of the design of the boiler 
which is dependent in part on the type of fuel being burned.
    Because these different types of boilers have different emission 
characteristics which may influence the feasibility and effectiveness 
of emission control, we are proposing to subcategorize them as follows: 
boilers designed to fire coal, boilers designed to fire biomass, and 
boilers designed to fire oil in order to account for these differences 
in emissions. The coal-fired subcategory includes boilers burning 
greater than 10 percent coal on an annual fuel heat input basis. The 
biomass fuel subcategory includes units burning any biomass but not 
more than 10 percent coal on an annual fuel heat input basis. The oil 
subcategory includes all remaining boilers.
    In summary, we have identified three subcategories of boilers 
located at area sources: (1) Boilers designed for coal firing, (2) 
boilers designed for biomass firing, and (3) boilers designed for oil 
firing.

C. What surrogates are we using?

    As explained above, EPA is proposing emission standards for the two 
source categories in this proposed rule. For mercury from coal-fired 
area source boilers and POM from all area source boilers, EPA is 
proposing these standards under CAA sections 112(d)(2) and 112(h). For 
the other urban HAP which formed the basis of the CAA section 112(c)(3) 
listing, EPA is proposing standards pursuant to CAA section 112(d)(5).
    In selecting the proposed emission standards, we are using PM as a 
surrogate for the non-mercury metallic urban HAP (arsenic, beryllium, 
cadmium, chromium, lead, manganese, and nickel). The inherent 
variability and unpredictability of the non-mercury metal HAP 
compositions and amounts in fuel have a material effect on the 
composition and amount of non-mercury metal HAP in the emissions from 
the boiler. As a result, establishing individual numerical emissions 
limits for each non-mercury HAP metal species is difficult given the 
level of uncertainty about the individual non-mercury metal HAP 
compositions of the fuels that will be combusted. An emission 
characteristic common to all boilers is that the non-mercury metal HAP 
are a component of the PM contained in the fly ash emitted from the 
boiler. A sufficient correlation exists between PM and non-mercury 
metallic HAP to rely on PM as a surrogate for these HAP and for their 
control. Therefore, the same control techniques that would be used to 
control the fly-ash PM will control non-mercury metallic HAP. Emissions 
limits established to achieve control of PM will also achieve control 
of non-mercury metal HAP. Consequently, we used PM as a surrogate for 
the non-mercury metal urban HAP in establishing emissions limits. The 
use of PM as a surrogate will also eliminate the cost of performance 
testing to comply with numerous standards for individual non-mercury 
metals.
    We looked at mercury separately from other metallic urban HAP due 
to its different chemical characteristics and applicable controls.
    For the organic urban HAP listed for these source categories (POM, 
acetaldehyde, acrolein, dioxins, PCB, and formaldehyde), we used CO as 
a surrogate to represent the organic urban HAP emitted from the 
boilers. The presence of CO is an indicator of incomplete combustion. A 
high level of CO in emissions is an indicator of incomplete combustion 
and, thus, a potential indication of elevated organic HAP emissions. 
Monitoring equipment for CO is readily available, which is not the case 
for organic HAP. Also, it is significantly easier and less expensive to 
measure and monitor CO emissions than to measure and monitor emissions 
of each individual organic HAP. We considered other surrogates, such as 
THC, but lacked data on emissions and permit limits for area source 
boilers. Therefore, using CO as a surrogate for organic urban HAP is a 
reasonable approach because min