[Federal Register Volume 76, Number 49 (Monday, March 14, 2011)]
[Proposed Rules]
[Pages 13852-13878]
[FR Doc No: 2011-5530]

Vol. 76

Monday,

No. 49

March 14, 2011

Part V

Environmental Protection Agency

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40 CFR Part 63

National Emission Standards for Hazardous Air Pollutants: Mercury
Emissions From Mercury Cell Chlor-Alkali Plants; Proposed Rule

Federal Register / Vol. 76 , No. 49 / Monday, March 14, 2011 /
Proposed Rules

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 63

[EPA-HQ-OAR-2002-0017; FRL-9278-5]
RIN 2060-AN99

National Emission Standards for Hazardous Air Pollutants: Mercury
Emissions From Mercury Cell Chlor-Alkali Plants

AGENCY: Environmental Protection Agency (EPA).

ACTION: Supplemental proposed rule.

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SUMMARY: This action proposes amendments to the national emission
standards for hazardous air pollutants (NESHAP) for mercury emissions
from mercury cell chlor-alkali plants (Mercury Cell NESHAP). On June
11, 2008, EPA proposed amendments to this NESHAP in response to a
petition for reconsideration filed by the Natural Resources Defense
Council (NRDC). This action is a supplement to the June 11, 2008,
proposal. Specifically, this action proposes two options for amending
the NESHAP for mercury emissions from mercury cell chlor-alkali plants.
The first option would require the elimination of mercury emissions and
thus encourage the conversion to non-mercury technology. The second
option would require the measures proposed in 2008. These measures,
which included significant improvements in the work practices to reduce
fugitive emissions from the cell room, would result in near-zero levels
of mercury emissions while still allowing the mercury cell facilities
to continue to operate. We are specifically requesting comment on which
of these options is more appropriate, and may finalize either option or
a combination of elements from them. In addition, this action proposes
several amendments that would apply regardless of which option we
select. These proposed amendments are provisions of the existing NESHAP
that would apply to periods of startup, shutdown, and malfunction
(SSM), and corrections to compliance errors in the currently effective
rule.

DATES: Comments must be received on or before May 13, 2011. Under the
Paperwork Reduction Act, comments on the information collection
provisions must be received by the Office of Management and Budget
(OMB) on or before April 13, 2011.
    Public Hearing. If anyone contacts EPA by March 29, 2011 requesting
to speak at a public hearing, EPA will hold a public hearing on April
13, 2011. If a public hearing is held, it will be held at EPA's Campus
located at 109 T.W. Alexander Drive in Research Triangle Park, NC, or
an alternate site nearby. Contact Virginia Hunt at<PHONE_NUMBER> to
request a hearing, to determine if a hearing will be held, or to
determine the hearing location. If no one contacts EPA requesting to
speak at a public hearing concerning this proposed rule by March 29,
2011, the hearing will be cancelled without further notice.

ADDRESSES: You may submit comments, identified by Docket ID No. EPA-HQ-
OAR-2002-0017, by any of the following methods:
     Federal eRulemaking Portal: http://www.regulations.gov:
Follow the instructions for submitting comments.
     Agency Web Site: http://www.epa.gov/oar/docket.html.
Follow the instructions for submitting comments on the EPA Air and
Radiation Docket Web site.
     E-mail<EMAIL_ADDRESS>Include Docket ID No. EPA-
HQ-OAR-2002-0017 in the subject line of the message.
     Fax:<PHONE_NUMBER>.
     Mail: National Emission Standards for Hazardous Air
Pollutants for Mercury Cell Chlor-alkali Plants Docket, Environmental
Protection Agency, EPA Docket Center (EPA/DC), Air and Radiation
Docket, Mail Code 2822T, 1200 Pennsylvania Ave., NW., Washington, DC
20460. Please include a total of two copies. In addition, please mail a
copy of your comments on the information collection provisions to the
Office of Information and Regulatory Affairs, Office of Management and
Budget (OMB), Attn: Desk Officer for EPA, 725 17th St., NW.,
Washington, DC 20503.
     Hand Delivery: EPA Docket Center, Public Reading Room, EPA
West, Room 3334, 1301 Constitution Ave., NW., Washington, DC 20460.
Such deliveries are only accepted during the Docket's normal hours of
operation, and special arrangements should be made for deliveries of
boxed information.
    Instructions: Direct your comments to Docket ID No. EPA-HQ-OAR-
2002-0017. EPA's policy is that all comments received will be included
in the public docket without change and may be made available online at
http://www.regulations.gov, including any personal information
provided, unless the comment includes information claimed to be
confidential business information (CBI) or other information whose
disclosure is restricted by statute. Do not submit information that you
consider to be CBI or otherwise protected through http://www.regulations.gov or e-mail. The http://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 http://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.
    Docket: All documents in the docket are listed in the http://www.regulations.gov index. Although listed in the index, some
information is not publicly available, e.g., CBI or other information
whose disclosure is restricted by statute. Certain other material, such
as copyrighted material, is not placed on the Internet and will be
publicly available only in hard copy form. Publicly available docket
materials are available either electronically through http://www.regulations.gov or in hard copy at the National Emission Standards
for Hazardous Air Pollutants for Mercury Cell Chlor-alkali Plants
Docket, EPA/DC, EPA West, Room 3334, 1301 Constitution Ave., NW.,
Washington, DC. The Public Reading Room is open from 8:30 a.m. to 4:30
p.m., Monday through Friday, excluding legal holidays. The telephone
number for the Public Reading Room is<PHONE_NUMBER>, and the telephone
number for the Air Docket is<PHONE_NUMBER>.

FOR FURTHER INFORMATION CONTACT: Sharon Nizich, Sector Policies and
Programs Division, Office of Air Quality Planning and Standards (D243-
02), Environmental Protection Agency, Research Triangle Park, North
Carolina 27711, telephone number:<PHONE_NUMBER>; fax number: (919)
541-5450; e-mail address<EMAIL_ADDRESS>
SUPPLEMENTARY INFORMATION:
    The supplementary 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 history of the Mercury Cell NESHAP?
    B. What petitions were filed after promulgation of the Mercury
Cell NESHAP in 2003?
    C. What were the reconsideration decisions proposed in 2008?
    D. What current legislation is related to this effort?
III. Summary of Proposed Amendments
    A. What is the non-mercury technology option (Option 1)?
    B. What is the enhanced work practices option (Option 2)?
    C. What amendments are being proposed that are independent of
which option is selected?
IV. Request for Comment
V. Statutory and Executive Order Reviews
    A. Executive Order 12866: Regulatory Planning and Review
    B. Paperwork Reduction Act
    C. Regulatory Flexibility Act
    D. Unfunded Mandates Reform Act
    E. Executive Order 13132: Federalism
    F. Executive Order 13175: Consultation and Coordination with
Indian Tribal Governments
    G. Executive Order 13045: Protection of Children from
Environmental Health 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 this
proposed action include:

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                                                  Examples of regulated
            Category              NAICS code\1\          entities
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Industry.......................          325181  Alkalis and Chlorine
                                                  Manufacturing.
Federal government.............  ..............  Not affected.
State/local/Tribal government..  ..............  Not affected.
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\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 would be regulated by this
action, you should examine the applicability criteria in 40 CFR 63.7682
of subpart IIIII, National Emission Standards for Hazardous Air
Pollutants (NESHAP): Mercury Emissions from Mercury Cell Chlor-Alkali
(hereafter called the ``2003 Mercury Cell NESHAP''). If you have any
questions regarding the applicability of this action to a particular
entity, consult either the air permitting 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 http://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), Environmental Protection Agency, Office of
Air Quality Planning and Standards, Research Triangle Park, North
Carolina 27711, Attention Docket ID EPA-HQ-OAR-2002-0017. 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.

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

D. When would a public hearing occur?

    If anyone contacts EPA requesting to speak at a public hearing
concerning the proposed amendments by March 24, 2011, we will hold a
public hearing on April 13, 2011. If you are interested in attending
the public hearing, contact Ms. Virginia Hunt at<PHONE_NUMBER> to
verify that a hearing will be held. If a public hearing is held, it
will be held at 10 a.m. at the EPA's Environmental Research Center
Auditorium, Research Triangle Park, NC, or an alternate site nearby.

II. Background Information

A. What is the history of the Mercury Cell NESHAP?

    On December 19, 2003, EPA promulgated the 2003 Mercury Cell NESHAP
(40 CFR part 63, subpart IIIII, 68 FR 70904). This rule for mercury
cell chlor-alkali plants implements section 112(d) of the Clean Air Act
(CAA), which requires all categories and subcategories of major sources
listed under section 112(c) to meet hazardous air pollutant emission
standards reflecting the application of the maximum achievable control
technology (MACT). Mercury cell chlor-alkali plants are a subcategory
of the chlorine production source category listed under the authority
of section 112(c)(1) of the CAA. In addition, mercury cell chlor-alkali
plants are listed as an area source category under section 112(c)(3)
and (k)(3)(B) of the CAA. The 2003 Mercury Cell NESHAP satisfied our
requirement to issue 112(d) regulations under each of these listings
(for mercury). The 2003 Mercury Cell NESHAP required both existing
major and area sources to meet mercury emission limits on stack
emission sources from both chlorine production and from the recovery of
mercury from wastes and other scrap in mercury thermal recovery units.
The 2003 Mercury Cell NESHAP also required the facilities to monitor
and minimize fugitive mercury emissions from the cell room by
conducting either daily work practices or work practices performed in
response to high levels of mercury emissions determined from continuous
mercury monitoring. The 2003 rule required facilities to comply with

applicable emission limitations and work practice requirements at all
times, except during periods of SSM. Finally, the 2003 Mercury Cell
NESHAP prohibited mercury emissions from new and reconstructed
facilities.

B. What petitions were filed after promulgation of the Mercury Cell
NESHAP in 2003?

    On February 17, 2004, the NRDC submitted an administrative petition
to EPA asking us to reconsider several aspects of the 2003 Mercury Cell
NESHAP under CAA section 307(d)(7)(B). On the same day as the
administrative petition, NRDC and the Sierra Club also filed a petition
for judicial review of the 2003 Mercury Cell NESHAP in the U.S. Court
of Appeals for the DC Circuit (Civ. No. 04-1048).
    By a letter dated April 8, 2004, Jeffrey Holmstead, then-EPA
Assistant Administrator for the Office of Air and Radiation, notified
the NRDC that EPA had granted NRDC's petition for reconsideration of
the 2003 Mercury Cell NESHAP. On July 20, 2004, the Court granted EPA's
motion to hold the case for judicial review in abeyance pending EPA's
action on the reconsideration of the 2003 Mercury Cell NESHAP.

C. What were the reconsideration decisions proposed in 2008?

    On June 11, 2008 (73 FR 33257), EPA responded to NRDC's petition
for reconsideration. In their petition, NRDC asked EPA to reconsider
five issues: (1) The decision to develop a set of work practice
requirements under CAA section 112(h) in lieu of a numeric emission
limitation for cell rooms; (2) the decision to make the promulgated
work practices optional for sources that choose to undertake continuous
monitoring; (3) the decision to not require existing facilities to
convert to a non-mercury chlorine manufacturing process; (4) the
elimination of the previously applicable part 61 rule's 2,300 grams/day
plant-wide emission limitation; and (5) the decision to create a
subcategory of mercury cell chlor-alkali plants within the chlorine
production category. In the 2008 proposal, EPA addressed each of these
issues and proposed amendments where we determined them to be
appropriate. Following are brief summaries of our reconsideration
decisions. For a full explanation of these decisions and the rationale
supporting them, please see the preamble for the June 11, 2008 proposal
(73 FR 33258). The 2008 proposed amendments, which are being co-
proposed in this action as Option 2, are discussed in section III.B of
this document.
    In addition, while not specifically listed as a major issue in
their petition, the uncertainty related to the magnitude of fugitive
mercury emissions was clearly a basis for much of NRDC's concern. This
was also addressed in the 2008 proposal and is summarized below after
the five specific issues cited by NRDC in the petition.
1. Emission Limitation for Cell Room
    In its petition for reconsideration, NRDC stated that EPA failed to
adequately justify that a numeric emission limitation was not feasible
per the criteria prescribed in section 112(h) of the CAA. In our 2008
reconsideration, we concluded that it is not feasible to prescribe or
enforce an emission limitation for fugitive emissions from the cell
room. We maintained that fugitive emissions from mercury cells and
associated equipment are a clear example of the type of situation to be
addressed by the provisions of section 112(h). The various points which
led to our opinion on the feasibility of establishing an emission
standard were discussed in detail in the 2008 proposal (73 FR 33267-
33271). In summary, consistent with CAA section 112(h), we believe that
it is not feasible to prescribe or enforce an emission standard in this
case. There are two independent bases for this conclusion. First,
consistent with CAA section 112(h)(2)(A), we concluded that fugitive
mercury emissions from a mercury cell chlor-alkali plant cannot be
emitted through a conveyance designed and constructed to emit or
capture such pollutant. Second, consistent with CAA section
112(h)(2)(B), we established that the application of measurement
technology to mercury cell rooms is not practicable due to
technological and economic limitations.
2. Optional Work Practices
    The 2003 Mercury Cell NESHAP requires facilities to follow a set of
detailed work practices. The NESHAP also allows facilities to institute
a cell room monitoring program to continuously monitor the mercury
vapor concentration in the upper portion of each cell room as an
alternative to these work practice standards. One of the objections
raised by NRDC was that this provision backtracked from the Agency's
proposed work practice standards. NRDC pointed out that in the
development of the Mercury Cell NESHAP, EPA concluded that the
housekeeping activities that facilities in the industry follow to
comply with the part 61 mercury NESHAP (40 CFR 61, subpart E)
represented the MACT floor and that requiring practices based upon the
most detailed activities in the industry (i.e., ``beyond-the-floor''
practices) was justified. But NRDC was concerned because the work
practices in the 2003 Mercury Cell NESHAP were optional if facilities
chose to do continuous monitoring and, therefore, this option would
allow sources to avoid conducting activities that represent the MACT
floor. NRDC argued that this was a violation of section 112(d)(3) of
the CAA, which requires all facilities to meet the MACT floor.
    As a result of our consideration of NRDC's point, we included
proposed amendments in 2008 that would require that all plants
institute a cell room monitoring program and comply with work practice
standards (73 FR 33271-33272). As part of today's action, we are re-
proposing the combination of work practices and cell room monitoring
program as option 2. The specific proposed amendments are discussed in
section III.B of this document.
3. Requiring Conversion to a Non-Mercury Chlorine Manufacturing Process
    In its petition, NRDC argued that the 2003 Mercury Cell NESHAP does
nothing to limit the use of mercury cell technology by existing chlor-
alkali plants, and that the Agency ignored a known technique for
reducing mercury emissions from this industry, namely, conversion to
non-mercury processes. According to NRDC, requiring the industry to
convert to a non-mercury process is cost-justified and would provide
significant non-air quality benefits. In response to NRDC's concerns
that we did not evaluate the conversion of mercury cell chlor-alkali
production plants to non-mercury technology, we performed an analysis
to estimate the capital and annual costs of this action. In performing
the analysis, we used information from all readily available sources of
information. Based on the results of this analysis, we proposed to
reject the option of requiring conversion to non-mercury technology
because of the high cost impact this forced conversion would impose on
the facilities in the industry (73 FR 33274-33275).
    Following the 2008 proposal, one commenter provided detailed
comments on our proposed decision to not require existing facilities to
convert to a non-mercury chlorine manufacturing process. In addition to
comments on the EPA cost analysis described in our 2008 proposal, the
commenter provided a report to support its comments. We

reviewed these comments, examined the commenter's report, and concluded
that our cost analysis could be improved. Therefore, we incorporated
some aspects of the commenter's cost analysis, and gathered additional
cost information. The results of our revised analyses, and our
consideration of the policy and legal comments made by the commenter
regarding the benefits of non-mercury technology to produce chlorine,
provided the impetus for the non-mercury mercury option being proposed
today as Option 1. Details of this proposed option are provided in
section III.A of this document.
4. Elimination of Part 61 NESHAP Numeric Limit
    NRDC stated that EPA illegally eliminated the 2,300 g/day limit on
plant-wide mercury emissions that existed under the part 61 Mercury
NESHAP. Upon reconsideration, we disagreed with NRDC's argument. We
determined that the plant-wide emission limit from the part 61 Mercury
NESHAP was a standard to which no mercury cell facility had ever
demonstrated compliance by way of emissions testing, that it is not an
enforceable standard today, and, more importantly, and that it did not
reflect the MACT level of emissions control required under CAA section
112(d)(3)(B). Therefore, we concluded that we did not unlawfully remove
any actual requirement of the part 61 Mercury NESHAP. Instead, the 2003
Mercury Cell NESHAP adopted a set of MACT-level work practice
requirements under section 112(h) that are more stringent in terms of
controlling fugitive mercury emissions than was allowed in the part 61
NESHAP. Details on this conclusion were provided on pages 73 FR 33270
and 33271 of the June 11, 2008 proposal.
5. Mercury Cell Chlor-Alkali Subcategory
    As stated in the preamble to the final 2003 Mercury Cell NESHAP (68
FR 70905), we divided the chlorine production source category into two
subcategories: (1) Mercury cell chlor-alkali plants and (2) chlorine
production plants that do not rely upon mercury cells for chlorine
production. In December 2003 (68 FR 70949), we issued our final
decision to delete the subcategory of the chlorine production source
category for chlorine production plants that do not utilize mercury
cells to produce chlorine and caustic. This action was made under our
authority in CAA section 112(c)(9)(B)(ii), and was not challenged in a
petition for judicial review. Nor did anyone ask us to reconsider that
action pursuant to CAA section 307(d)(7)(B). The objection raised by
NRDC in its petition for reconsideration of the 2003 Mercury Cell
NESHAP was that it was not appropriate to create a mercury cell chlor-
alkali plants subcategory. According to NRDC, if the MACT floor for
mercury emissions was determined for the chlorine production source
category as a whole, the best-performing 12 percent of sources in the
category would be mercury-free. In our 2008 proposal (73 FR 33273-
33274), we explained that EPA has a long history of using
subcategorization to appropriately differentiate between types of
emissions and/or types of operations when analyzing whether air
pollution control technology is feasible for groups of sources. Upon
reconsideration of this situation for mercury cell chlor-alkali plants,
we concluded that our earlier decision to create the mercury cell
chlor-alkali plant subcategory was sound.
6. Magnitude of Fugitive Mercury Emissions
    Prior to 2008, the uncertainty associated with fugitive mercury
emissions from mercury cell chlor-alkali plants had long been an issue.
Few studies had been conducted to measure these fugitive mercury
emissions, and the studies that had been conducted were short-term and
did not account for a range of operating and maintenance conditions.
For around 30 years, mercury cell chlor-alkali plants had reported
fugitive mercury emissions of 1,300 grams per day (g/day), which
equates to around 0.5 tons per year per plant. These estimates were
based on two limited studies conducted by EPA in the early 1970's.
    The sensitivity and concern over the actual levels of fugitive
mercury emissions from the cell rooms was exacerbated by the inability
of the industry to fully account for all the mercury that was added to
the cells. In 2000, there were approximately 65 tons of mercury
unaccounted for at the 12 mercury cell plants in operation at that
time. This discrepancy was based on the difference between the amount
of mercury used, as reported in the Chlorine Institute's 2001 annual
report to EPA's Binational Toxics Strategy Mercury Workgroup,\a\ and
the amount of mercury released to all media, as reported in the 2000
Toxics Release Inventory, or TRI (the EPA requires industrial
facilities to annually report on releases and transfers of certain
toxic chemicals to a public database known as the TRI.) While industry
representatives provided explanations for this discrepancy, they could
not fully substantiate their theories. NRDC maintained that this
``missing'' mercury was being emitted as fugitive emissions.
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    \a\ Binational Toxics Strategy Mercury Workgroup--Reducing
Mercury in the Great Lakes Region. U.S. Environmental Protection
Agency. http://www.epa.gov/reg5oair/mercury/reducing.html#regulation.
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    We recognized that the body of fugitive mercury emissions data
could be improved. Therefore, as part of our reconsideration of the
2003 Mercury Cell NESHAP, we collected additional information on
fugitive mercury emissions from mercury cell chlor-alkali plants. The
primary purpose of this effort was to address whether the fugitive
emissions from a mercury cell chlor-alkali plant are on the order of
magnitude of the historical assumption of 1,300 g/day, corresponding to
0.5 tons per year (tpy) per plant, or an order of magnitude higher as
estimated by NRDC.
    Consequently, as part of our reconsideration efforts leading the
2008 proposal, we sponsored a test program to address the issue of the
magnitude of the fugitive mercury emissions at mercury cell chlor-
alkali plants. In addition to this EPA test program, we also collected
mercury emissions data from the continuous mercury monitoring systems
installed at three mercury cell plants.
    The daily fugitive mercury emission rates extrapolated from these
data sets ranged from around 20 to 1,300 g/day per facility. The
average daily emission rates ranged from around 420 g/day to just under
500 g/day per facility, with the mean of these average values being
slightly less than 450 g/day per facility. Therefore, the information
we obtained in the almost one million dollar study of fugitive
emissions from mercury cell chlor-alkali plants shows that fugitive
emissions are on the order of magnitude of the historical assumption of
1,300 g/day or less. There was no evidence obtained during any of the
studies that indicated that fugitive mercury emissions were at levels
higher than 1,300 g/day. All of the studies that produced these data
were of sufficient duration to encompass all types of maintenance
activities. Further, the length of these studies was also sufficient to
include emissions from a variety of process upsets, such as: Liquid
mercury spills, leaking cells and other process equipment, and other
process upsets.
    We also note that since 2008, the mercury cell plants with
continuous monitoring systems and methods to estimate the flow rates
have reported even lower mercury emissions than

those reported in the 2008 proposal. In 2008, these plants reported
fugitive mercury emissions averaging around 225 g/day/plant.

D. What current legislation is related to this action?

    There is also U.S. legislation, both recently enacted and proposed,
that has or will have an impact on these mercury chlor-alkali
facilities. On October 14, 2008, President Bush signed the Mercury
Export Ban Act of 2008 into law. This law bans U.S. export of elemental
mercury (effective in 2013), requires the Department of Energy (DOE) to
designate and manage a long-term storage facility for elemental
mercury, and prohibits the transfer of elemental mercury by Federal
agencies.
    Both houses of Congress are currently considering legislation that,
if enacted, would affect this industry (S. 1428 and H.R. 2190). These
bills would amend the Toxic Substances Control Act to prohibit the use
of mercury at chlor-alkali facilities. The House bill would require the
facilities to cease using mercury by 2013 if the plant chooses to close
or by 2015 if the plant chooses to convert to non-mercury. If this
legislation passes Congress and is signed by the President into law, we
will evaluate the appropriate action for EPA in light of the scope and
impact of the law.

III. Summary of Proposed Amendments

    In today's action, we are proposing two options for amending the
Mercury Cell NESHAP. The first option (non-mercury technology option)
would encourage the conversion to non-mercury technology by requiring
the elimination of mercury emissions. The second option (enhanced work
practices option) would require improvements in the work practice
standards to reduce fugitive emissions from the cell room including the
requirement that every facility institute a cell room monitoring
program and implement detailed work practices. These options, along
with the estimated impacts of each, are described below in sections
III.A and III.B. Also included is rationale for the selection of each
option.
    In addition to these options, we are also proposing amendments that
would apply regardless of which option we select. These amendments are
described in section III.C.

A. What is the non-mercury technology option (Option 1)?

1. Summary of Non-Mercury Technology Option
    This proposed option would amend the 2003 Mercury Cell NESHAP by
prohibiting mercury emissions from existing mercury cell chlor-alkali
plants. This would make the standard for existing sources the same as
the current standard for new and reconstructed sources, which is
codified at 40 CFR 63.8190(a)(1).
    Since we believe it is improbable that a mercury cell chlor-alkali
plant can be operated without mercury emissions, we believe that this
proposal would effectively require existing mercury cell chlor-alkali
plants either to convert to a non-mercury technology or to cease
production of chlorine with their current mercury cell production
methods. However, if there are circumstances where the elimination of
mercury emissions from an operating mercury cell plant could be
achieved, we are interested in data and supporting information
regarding technologies that would eliminate mercury emissions from an
operating mercury cell facility.
    This proposed option would provide a three-year period from the
date the final rule is published in the Federal Register to comply. To
demonstrate compliance, each owner or operator would have to submit a
report certifying that all mercury emissions have been eliminated
permanently. This report would have to be submitted no later than 120
days following the applicable compliance date.
2. Technical Information and Analyses for the non-Mercury Technology
Option
a. Background on the 2008 Proposal and Costs Analysis
    Section 112(d)(2) of the CAA provides that emission standards for
new or existing sources of hazardous air pollutants (HAP) shall require
the maximum degree of reduction in emissions (including a prohibition
on such emissions, where achievable) that EPA, taking into
consideration the cost of achieving such emission reduction, and any
non-air quality health and environmental impacts and energy
requirements, determines is achievable through application of measures,
processes, methods, systems or techniques. These may include, but are
not limited to, measures which (A) Reduce the volume of or eliminate
emissions through process changes, substitution of materials or other
modifications; (B) enclose systems or processes to eliminate emissions;
(C) collect, capture or treat such pollutants when released from a
process, stack, storage or fugitive emission point; (D) are design,
equipment, work practice, or operational standards; or (E) are a
combination of the above.
    One of the claims presented in NRDC's petition for reconsideration
of the 2003 Mercury Cell NESHAP was that EPA had not adequately
considered non-mercury technology as a ``beyond-the-floor'' MACT
control measure for existing sources in the original rulemaking for the
Mercury Cell NESHAP (see section II.D.3). Further, NRDC claimed that
the cost-effectiveness of such a requirement, in terms of the
annualized costs of control per pound of mercury eliminated, would be
less than EPA previously indicated was warranted for mercury emissions
from the mercury cell subcategory.
    In response to this comment, we performed an analysis in 2008 to
determine the capital and annual costs of requiring non-mercury
technology (Docket Item EPA-HQ-OAR-2002-0017-0088). Specifically, this
analysis estimated the costs and the cost-effectiveness of converting
the existing mercury cell chlor-alkali plants to membrane cells.
    In a chlor-alkali process, an electric current is passed through a
salt solution or brine (sodium chloride or potassium chloride), causing
the dissociation of salt to produce chlorine gas and an alkaline
solution (sodium hydroxide or potassium hydroxide). Hydrogen gas is
also produced as a by-product. This dissociation occurs in chlor-alkali
``cells,'' where the chloride ions stripped from the brine flow to the
anode to form the chlorine product, and the sodium/potassium ions flow
to the cathode, where they form the hydroxide product and hydrogen. In
a mercury cell, the cathode is a flowing layer of liquid mercury. The
sodium/potassium ions form an amalgam with the mercury, which is routed
to a decomposer. In the decomposer, the amalgam is reacted with water
to form the hydroxide product and hydrogen. The mercury is then
recycled.
    In a membrane process, a polymer membrane is used to separate the
anode products from the cathode products. The chloride ions (at the
anode) and the hydrogen (at the cathode) are kept apart by this
membrane, which allows the sodium ions to pass into the cathodic
compartment and react to form the hydroxide.
    Conversion from mercury cells to membrane cells is technically
possible at all existing mercury cell chlor-alkali plants, although the
amount of significant changes will vary for each individual situation.
There are parts of the mercury cell plant that could be re-used after
conversion to the membrane cells. It could be possible to use the
existing cell room building for the new

membrane cells, provided that the building is in good condition.
However, constructing a new membrane cell room building would reduce
the production losses as the mercury cells could continue to operate
longer throughout the conversion process. Other equipment and processes
that possibly could be retained include the rectifiers, the hydrogen
treatment system, and the chlorine compression and liquefaction
process.
    The mercury cells themselves (and associated decomposers) would
have to be replaced by membrane cells. Membrane cells need purer brine
than mercury cells, so a completely new brine purification system would
likely be needed. Other equipment that would commonly need to be
totally replaced include the sodium/potassium hydroxide concentration
unit and evaporation system, the chlorine gas drying and chlorine gas
absorption units, the power supply unit (excluding the rectifiers),
pumps, instruments, and much of the piping.
    In performing the cost analysis, we used data from readily-
available sources of information. In our 2008 proposal, we estimated
that the average cost-effectiveness associated with conversion to non-
mercury technology would be approximately $14,000 per pound of mercury
emissions eliminated. Further, our 2008 analysis estimated the average
capital cost of conversion for one mercury cell chlor-alkali facility
in the U.S. to be approximately $68 million per plant. The average
annualized facility costs for this conversion were estimated to be
approximately $7.5 million per plant. Nationwide, the capital cost was
estimated to be nearly $340 million and the annual costs around $38
million for the five facilities in operation at the time. We estimated
that this cost impact would be approximately 11 percent of revenues. As
a result of these analyses, we proposed in 2008 to reject conversion to
non-mercury technology as a beyond-the-floor control requirement.
b. Summary of Comments Received on the 2008 Cost Analysis
    One environmental organization disagreed with both our technical
analysis and resulting conclusions in the 2008 proposal, and claimed
that the switch to non-mercury technology would be economical. The
commenter said that, in the 2008 analysis, EPA considered only the
costs associated with the conversion, without considering the net cost
or economic benefit. The commenter maintained that it is likely that
any plant that converts will experience substantial benefits, including
an increase in energy efficiency between 25 and 35 percent. The
commenter claimed that this increased energy efficiency could amount to
substantial savings. Furthermore, the commenter pointed out that
membrane cells are smaller than mercury cells, which would allow plants
to increase their chlorine capacity, leading to increased sales and
additional energy savings due to the additional capacity. The commenter
submitted a report that it prepared which provided individualized cost
analyses for each of the remaining mercury cell chlor-alkali plants
(Docket Item EPA-HQ-OAR-2002-0017-0094.3). According to the commenter,
its report proves that conversion would pay for the majority of its
cost in five years. Thus, the commenter concluded that EPA's proposal
was incorrect to suppose a ``high cost impact'' of conversion to non-
mercury technology, and claimed that EPA should heed the evidence that
conversion is not only economically feasible but beneficial and mandate
conversion to non-mercury technology as a beyond-the-floor control
requirement.
c. 2009 Revised Cost Analyses
    In the second quarter of 2009, we performed a revised beyond-the-
floor cost analysis to address comments received on the 2008 proposed
amendments described above. The impacts, particularly the savings and
benefits, of a forced conversion to membrane cells might not be
universally applicable since the conditions and benefits are not the
same at every facility. We do agree, however, that these facilities
would achieve some savings associated with lower electricity and the
elimination of environmental compliance costs for water treatment,
waste disposal, and mercury monitoring, and that items should be added
to the EPA cost analyses. Therefore, without assuming that a uniform
energy savings would accrue to every facility currently operating, we
updated our analysis to consider the energy costs savings. We also
amended our analysis to include savings from the elimination of waste
treatment, waste disposal, and mercury monitoring. On June 5, 2009, we
developed a revised and updated analysis of conversion costs for the
industry. This analysis was posted as a memorandum in the docket
(Docket Item EPA-HQ-OAR-2002-0017-0098).
    Subsequent to the posting of the June 5, 2009, memorandum, industry
representatives provided comments on the revised analysis (Docket Items
EPA-HQ-OAR-2002-0017-0100, 0101, 0102, and 0103). One of the major
comments raised by industry representatives on our revised analysis
regarded the 2006 mercury emission levels used to estimate the cost-
effectiveness of conversion to non-mercury technology. The industry
representatives stated that these data reflected emission levels
considerably higher than their more recently reported emissions. In
addition, the industry representatives stated that the capital and
annual costs in our 2008 analysis were underestimated. The industry
representatives also believed that the annual energy savings were
overstated because these savings did not take into account the
additional energy and fuel that would be needed to concentrate the
caustic by-product obtained using membrane cells, which is produced at
33 percent purity, to the 50 percent purity obtained using the mercury
cell process. The industry representatives also commented that the June
2009 cost analysis: (1) Underestimated the mercury storage costs; (2)
used an interest rate that was in practicality too low for calculating
the capital recovery factor; (3) erroneously used information from a
European study to estimate the savings due to the elimination of the
mercury process that were not applicable to the U.S.; and (4) did not
consider decommissioning costs.
    Consequently, we considered the industry comments and, in instances
where specific relevant data were provided or available, we
incorporated the information into another revised cost analysis dated
September 15, 2009 (Docket Item EPA-HQ-OAR-2002-0017-0105). The
September 2009 updated cost analysis for conversion to membrane
technology estimated that the costs to convert the four remaining
mercury cell plants to be nearly $336 million in total capital costs
and almost $36 million per year in total annual costs, considering
electricity and other savings. The cost-effectiveness of conversion
based on this September 2009 analysis was about $66,000 per pound of
mercury.
    In this analysis, we did not add certain highly variable costs
mentioned by the industry commenter that could potentially be incurred
by a plant when making a change to non-mercury technology. These
variable costs include losses in production, building replacement,
plant decommissioning, and many others that are likely to be highly
variable from facility to facility. We believe that the magnitude of
these costs, although very likely to occur for most facilities, would
depend on factors such as the condition of the existing buildings,
available space on the facility

site to erect a new cell room building to avoid production losses, and
possibly other unknown factors. We also received comments on the
revised 2009 cost analyses from the same environmental organization
that provided comments on the 2008 cost analysis. The complete comments
can be found in the docket (Docket EPA-HQ-OAR-2002-0017). The
environmental organization commenter stated that the capital costs
estimated by EPA are too high and the EPA analysis did not uniformly
account for expansion during conversion. In addition, the commenter
stated that the regression formula of cost vs. capacity used to
establish an equation is incorrect since there is no relationship
between capital costs and capacity when considering the full set of
relevant data rather than just recent U.S. facilities. Also, the
commenter stated that the capital costs should be annualized over a
longer period than the 15 years used in the analysis since 30 years is
a more likely useful life.
    The environmental commenter also made the following points: The
energy savings estimated by EPA are too low, since higher reductions in
electricity consumption are common place; the EPA cost estimate for
producing steam double-counted the cost associated with concentrating
caustic and did not account for the fact the steam could be obtained
on-site without expense; the cost savings for environmental compliance
avoided are underestimated; and the decommissioning costs are already
included in estimates of conversion since many factories include the
cost of dismantling and decommission in the reported cost of
conversion.
    In addition, the commenter recommended that in evaluating the
costs, EPA should use the average sales per establishment instead of
the average sales per ton of chlorine capacity because the commenter
believes that the latter term grossly underestimates sales. The
commenter also stated that societal costs of conversion to non-mercury
technology should be considered (Docket Item EPA-HQ-OAR-2002-0017-
0104). The commenter also believed that the industry-supplied emission
estimates are not reliable and are likely underestimated, thus
overestimating the costs per pound of mercury emissions prevented.
Finally, the commenter stated that EPA's overall conclusion does not
reflect the real world since over 100 plants have made the conversion
globally and at least five chlor-alkali facilities expected or received
a complete repayment from their investment within five years.
d. Revised Cost Analysis for This Proposal
    Many of the comments we received on the September 2009 cost
analysis were considered and used to estimate costs that represent the
outcome of a potential conversion to non-mercury technology. In this
revised analysis, we recognize that there are significant uncertainties
in estimating these costs, and consider ranges of the potential costs
(and savings) associated with each cost element. For each element, we
do select a ``best estimate'' to allow the estimation of capital and
annual costs of conversion for each facility. The results of this
analysis are summarized below in section III.A.2.a of this document,
and a memorandum that documents the details of this cost analysis can
be found in the docket. We are specifically requesting comment on our
analysis, along with additional facility-specific data, to allow a
refinement of the analysis.
3. Estimated Impacts of the Non-Mercury Technology Option
a. Environmental and Energy Impacts
    We estimate that the total mercury emissions from the four mercury
cell operating facilities to be around 640 pounds per year. The non-
mercury technology option would reduce mercury emissions by this
amount. These four facilities reported almost 2,000 additional pounds
per year of on-site and off-site mercury releases to non-air media.
These releases, which are primarily in the form of hazardous wastes,
would be eliminated in the longer term, with consequential benefits for
non-air quality related health and environmental values. The potential
problems associated with the handling and continuous management of over
1,200 tons of virgin mercury that is used in the cells at these four
chlor-alkali plants would also be eliminated. In addition,
approximately two tons of this mercury was reported by the industry as
``unaccounted'' in 2008. This non-mercury technology option would
eliminate the unaccounted mercury as well.
    The membrane cell chlor-alkali process requires less energy than
the mercury cell process. Therefore, assuming that all four existing
mercury cell chlor-alkali plants convert to membrane cells, there would
be a savings in energy. We estimate that this savings would be around
350,000 megawatt hours per year, which is approximately equivalent to
the energy produced annually by a 40 megawatt power plant. The emission
reductions associated with this reduced electricity generation are
estimated to be 68 tons per year of fine particulate matter
(PM2.5), 5 tons per year of volatile organic compounds
(VOC), 0.1 tons per year of ammonia (NH3) 0.008 tons per
year of mercury, and 287,000 tons per year of carbon dioxide
(CO2). Since nitrogen oxide (NOx) and sulfur dioxide
(SO2) are covered by capped emissions trading programs, we
are only estimating PM2.5 emission reductions from reduced
electricity demand.
    In the short term, the conversion of these facilities would result
in the need to dispose of mercury-contaminated wastes. While there is
considerable uncertainty in quantifying the amount of these wastes, we
estimate that there could be around 7,000 cubic meters of mercury
contaminated waste generated that could contain around 6 tons of
mercury.
    As stated above, over 1,200 tons of virgin or process mercury from
the facilities would need to be dealt with whether the facilities close
or convert to non-mercury technology. The Mercury Export Ban Act of
2008, discussed earlier, would prohibit this mercury from being
exported. Therefore, this mercury would need to be stored or sold
domestically. Since mercury is a hazardous substance, it cannot be
stored without a permit; hence, DOE is planning to build a Federal
facility to accommodate the excess mercury that results from the export
ban.
b. Cost Impacts
    The estimated costs for the non-mercury technology option, assuming
that all four currently operating mercury cell chlor-alkali plants
convert to membrane cell technology, include total capital costs of
approximately $300 million dollars, with individual plant capital costs
ranging from a low of $28 million to a high of approximately $160
million. Our analysis does show that, in the hypothetical situation
that a single plant could incur the lowest possible costs while also
realizing the highest possible energy and other savings, there could be
an overall cost savings in the conversion from mercury cells to
membrane cells. However, we do not believe that this scenario is
realistic. Using more conservative assumptions, our best estimate is
that the average annual costs would be between $800,000 and $7 million
per year per plant. The total annual costs are estimated to be $13
million per year. Based on these costs and the estimated mercury
emissions for each facility, the cost-effectiveness, in terms of
annualized costs per pound of mercury eliminated, is approximately
$20,000 per pound for the industry, with a range

of around $13,000 to $31,000 per pound for the individual facilities.
c. Economic Impacts
    In addition to cost analyses, we also conducted an economic
analysis of the impacts of the option to require non-mercury
technology. A regulatory impact analysis (RIA) was performed for this
non-mercury technology option. A report that documents the EIA methods
and results can be found in the docket (EPA-HQ-OAR-2002-0017).
    Although individual plant information would be the best method to
assess the true economic impacts of the non-mercury technology option,
detailed information for this industry was not publicly available. As a
result, we relied on parent company information provided in company
annual reports (e.g., form 10-K), local press and industry trade
publications, and company Web sites.
    There are many aspects of the cost estimate for conversion that are
unknown or difficult to assess. While we believe that we have evaluated
the conversion cost information available to us at the time of this
action, the true costs may vary considerably. However, variation in
engineering costs is not expected to cause a significant difference in
the general conclusions of the RIA.
    We performed an analysis that compared the annual conversion costs
to sales (cost to sales ratio, or CSR). We estimated that the CSR of
ASHTA, the one small business in this industry, would range from one to
two percent using the costs presented in this proposal. The other three
plants are owned by large parent companies with significant company-
wide sales. As a result, the CSRs for these large parent companies are
below one percent. When single plant sales were considered, the CSRs
for the mercury cell chlor-alkali plants owned by large parent
companies ranged from 4 to 9 percent.
    We also analyzed industry profitability effects by comparing the
annual conversion costs to reported industry margins for a
representative electrochemical unit. This analysis confirms the results
of the sales comparisons that plant conversion costs will likely have
an economically significant effect. Conversion costs could reduce the
margins by 10 to 20 percent.
    This non-mercury technology option would force owners of mercury
chlor-alkali plants to make an investment decision based on the costs
of conversion as opposed to the future benefits of the conversion. This
non-mercury technology option could lead to plant shutdowns that would
involve adjustment costs for people working at the affected plants.
Affected plants may also have strong links with other firms or
downstream markets; as a result, secondary consequences of the
regulation are important to consider. We are interested in receiving
comments related to the downstream impacts of potential mercury cell
plant shutdowns. In particular, we are interested in the impact on the
potassium carbonate market and the potential impact on the
competitiveness of the potassium hydroxide market.
    Many owners have converted from mercury cell chlor-alkali
technologies in Europe and the U.S., while other mercury cell chlor-
alkali plant owners have concluded the investment decision was
currently not in their company's interest given their assessment of
future economic conditions, and have shutdown their mercury cell chlor-
alkali plants instead. Since 2003, three U.S. mercury cell chlor-alkali
facilities have closed and three have converted. Specifically, the
Occidental Chemical mercury cell chlor-alkali facilities in Delaware
City, Delaware, Muscle Shoals, Alabama, and Deer Park, Texas, have
closed; while the PPG facility in Lake Charles, Louisiana, the ERCO
facility in Port Edwards, Wisconsin, and the Pioneer chlor-alkali
facility (now owned by Olin) in St. Gabriel, Louisiana, have converted
to membrane cells.
    We do not have sufficient data to predict whether individual
companies would choose to convert or close the affected mercury cell
chlor-alkali plants. However, the data obtained in this study suggests
that plant closure may be a preferred alternative to meet the
requirements of the non-mercury technology option for one or more of
the mercury cell chlor-alkali plants.
    As noted above, individual plant information was not available to
perform a refined analysis of whether these mercury cell plants would
likely convert to non-mercury technology or close. We are specifically
requesting comment on our analysis, along with facility-specific data,
to allow a refinement of the analysis for this non-mercury technology
option.
d. Benefits
    Mercury is a highly neurotoxic contaminant that enters the food web
as a methylated compound, methylmercury (U.S. EPA, 2008c). The
contaminant is concentrated in higher trophic levels, including fish
eaten by humans. Mercury is emitted to the air from various man-made
and natural sources. These emissions transport through the atmosphere
and eventually deposit to land or water bodies. This deposition can
occur locally, regionally, or globally, depending on the form of
mercury emitted and other factors such as the weather. The form of
mercury emitted from these sources is estimated to be about 98 percent
elemental and two percent divalent mercury. Gaseous elemental mercury
can be transported very long distances, even globally, to regions far
from the emissions source (becoming part of the global ``pool'') before
deposition occurs. Inorganic ionic (divalent) mercury has a shorter
atmospheric lifetime and can deposit to land or water bodies closer to
the emissions source. Furthermore, elemental mercury in the atmosphere
can undergo transformation into ionic mercury, providing a significant
pathway for deposition of emitted elemental mercury.
    This source category emitted about 640 pounds of mercury in the air
in 2008 in the U.S. Based on the EPA's National Emission Inventory,
about 103 tons of mercury were emitted from all anthropogenic sources
in the U.S. in 2005. Moreover, the United Nations has estimated that
about 2,100 tons of mercury were emitted worldwide by anthropogenic
sources in 2005. We believe that total mercury emissions in the U.S.
and globally in 2008 were about the same magnitude in 2005. Therefore,
we estimate that in 2008, these sources emitted about 0.3 percent of
the total anthropogenic mercury emissions in the U.S. and about 0.02
percent of the global emissions. Overall, the non-mercury technology
option (Option 1) would directly reduce mercury emissions by about 640
pounds per year from current levels as well as an estimated 16 pounds
per year indirectly through reduced electricity generation, and,
therefore, contribute to reductions in mercury exposures and health
effects. Due to data, time, and resource limitations, we were unable to
model mercury dispersion, deposition, methylation, bioaccumulation in
fish tissue, and human consumption of mercury-contaminated fish that
would be needed in order to estimate the human health benefits from
reducing mercury emissions.
    Potential exposure routes to mercury emissions include both direct
inhalation and consumption of fish containing methylmercury. For
elemental mercury, inhalation is the most direct exposure route of
potential concern. Effects on the nervous system appear to be the most
sensitive toxicological endpoint and can include tremors, nervousness,
insomnia, neuromuscular changes (such as weakness, muscle atrophy, and
muscle

twitching), and headaches.\b\ In the U.S., the primary route of human
exposure to mercury emissions from industrial sources is generally
indirectly through the consumption of fish containing methylmercury. As
described above, mercury that has been emitted to the air eventually
settles into water bodies or onto land where it can either move
directly or be leached into waterbodies. Once deposited, certain
microorganisms can change it into methylmercury, a highly toxic form
that builds up in fish, shellfish and animals that eat fish.
Consumption of fish and shellfish are the main sources of methylmercury
exposure to humans. Methylmercury builds up more in some types of fish
and shellfish than in others. The levels of methylmercury in fish and
shellfish vary widely depending on what they eat, how long they live,
and how high they are in the food chain. Most fish, including ocean
species and local freshwater fish, contain some methylmercury. For
example, in recent studies by EPA and the U.S. Geological Survey (USGS)
of fish tissues, every fish sampled from 291 streams across the country
contained some methylmercury (Scudder, 2009).\c\
---------------------------------------------------------------------------

    \b\ Integrated Risk Information System (IRIS). U.S.
Environmental Protection Agency. http://www.epa.gov/ncea/iris/subst/0370.htm.
    \c\ Scudder, B.C., Chasar, L.C., Wentz, D.A., Bauch, N.J.,
Brigham, M.E., Moran, P.W., and Krabbenhoft, D.P. 2009. Mercury in
fish, bed sediment, and water from streams across the United States,
1998-2005: U.S. Geological Survey Scientific Investigations Report
2009-5109, p. 74.
---------------------------------------------------------------------------

    The majority of fish consumed in the U.S. are ocean species. The
methylmercury concentrations in ocean fish species are primarily
influenced by the global mercury pool. However, the methylmercury found
in local fish can be due, at least partly, to mercury emissions from
local sources. Research shows that most people's fish consumption does
not cause a mercury-related health concern. However, certain people may
be at higher risk because of their routinely high consumption of fish
(e.g., Tribal and other subsistence fishers and their families who rely
heavily on fish for a substantial part of their diet). It has been
demonstrated that high levels of methylmercury in the bloodstream of
unborn babies and young children may harm the developing nervous
system, making the child less able to think and learn. Moreover,
mercury exposure at high levels can harm the brain, heart, kidneys,
lungs, and immune system of people of all ages.
    Several studies suggest that the methylmercury content of fish may
reduce these cardio-protective effects of fish consumption. Some of
these studies also suggest that methylmercury may cause adverse effects
to the cardiovascular system. For example, the National Research
Council (NRC) (2000) review of the literature concerning methylmercury
health effects took note of two epidemiological studies that found an
association between dietary exposure to methylmercury and adverse
cardiovascular effects.\d\ Moreover, in a study of 1,833 males in
Finland aged 42 to 60 years, Solonen et al. (1995) observed a
relationship between methylmercury exposure via fish consumption and
acute myocardial infarction (AMI or heart attacks), coronary heart
disease, cardiovascular disease, and all-cause mortality.\e\ The NRC
also noted a study of 917 seven year old children in the Faroe Islands,
whose initial exposure to methylmercury was in utero although post
natal exposures may have occurred as well. At seven years of age, these
children exhibited an increase in blood pressure and a decrease in
heart rate variability.\f\ Based on these and other studies, NRC
concluded in 2000 that, while ``the data base is not as extensive for
cardiovascular effects as it is for other end points (i.e., neurologic
effects) the cardiovascular system appears to be a target for
methylmercury toxicity.'' \g\
---------------------------------------------------------------------------

    \d\ National Research Council (NRC). 2000. Toxicological Effects
of Methylmercury. Committee on the Toxicological Effects of
Methylmercury, Board on Environmental Studies and Toxicology.
National Academies Press. Washington, DC. pp. 168-173.
    \e\ Salonen, J.T., Seppanen, K. Nyyssonen et al. 1995. ``Intake
of mercury from fish lipid peroxidation, and the risk of myocardial
infarction and coronary, cardiovascular and any death in Eastern
Finnish men.'' Circulation, 91 (3):645-655.
    \f\ Sorensen, N, K. Murata, E. Budtz-Jorgensen, P. Weihe, and
Grandjean, P., 1999. ``Prenatal Methylmercury Exposure as a
Cardiovascular Risk Factor at Seven Years of Age'', Epidemiology,
pp. 370-375.
    \g\ National Research Council (NRC). 2000. Toxicological Effects
of Methylmercury. Committee on the Toxicological Effects of
Methylmercury, Board on Environmental Studies and Toxicology.
National Academies Press. Washington, DC. p. 229.
---------------------------------------------------------------------------

    Since publication of the NRC report, there have been some 30
published papers presenting the findings of studies that have examined
the possible cardiovascular effects of methylmercury exposure. These
studies include epidemiological, toxicological, and toxicokinetic
investigations. Over a dozen review papers have also been published. If
there is a causal relationship between methylmercury exposure and
adverse cardiovascular effects, then reducing exposure to methylmercury
would result in public health benefits from reduced cardiovascular
effects.
    In early 2010, EPA sponsored a workshop in which a group of experts
were asked to assess the plausibility of a causal relationship between
methylmercury exposure and cardiovascular health effects and to advise
EPA on methodologies for estimating population level cardiovascular
health impacts of reduced methylmercury exposure. The report from that
workshop is in preparation.
    The primary benefit of the non-mercury technology option would be
the reduction of mercury emissions from these sources, as discussed
above. Due to data and resource limitations, we were unable to monetize
the benefits associated with reducing mercury emissions for this non-
mercury technology option. However, we estimate the monetized energy
co-benefits of the non-mercury technology option to be $22 million to
$43 million (2007$, 3 percent discount rate) in the implementation year
(2013). The monetized co-benefits of the regulatory action at a 7
percent discount rate are $14 million to $33 million (2007$). Higher or
lower co-benefits estimates are plausible using other assumptions.\h\ A
summary of the monetized energy co-benefits estimates at discount rates
of 3 percent and 7 percent is in Table 1 of this preamble.
---------------------------------------------------------------------------

    \h\ Roman et al, 2008. ``Expert Judgment Assessment of the
Mortality Impact of Changes in Ambient Fine Particulate Matter in
the U.S.'' Environ Sci Technol, 42, 7, 2268-2274.

 Table 1--Summary of the Monetized Co-Benefits Estimates for the Proposed Non-Mercury Technology Option in 2013
                                             (Millions of 2007$) \1\
----------------------------------------------------------------------------------------------------------------
                                                                 Monetized co-benefits    Monetized co-benefits
              Pollutant                   Estimated emission   -------------------------------------------------
                                              reductions           (3% Discount rate)       (7% Discount rate)
----------------------------------------------------------------------------------------------------------------
Mercury \2\..........................  656 pounds per year....  N/A....................  N/A
Direct PM2.5.........................  68 tons per year.......  $15 to $37.............  $14 to $33

CO2 3                                  287,000 tons per year..  $6.5...................  $6.5
Grand Total..........................  .......................  $22 to $43.............  $21 to $40
----------------------------------------------------------------------------------------------------------------
\1\ All estimates are for the implementation year (2013), and are rounded to two significant figures so numbers
  may not sum across rows. All fine particles are assumed to have equivalent health effects.
\2\ Includes an estimated 16 pounds per year of mercury emission reductions from energy savings.
\3\ CO2-related benefits were calculated using the social cost of carbon (SCC), which is discussed further in
  the RIA. The net present value of reduced CO2 emissions is calculated differently than other benefits. The
  same discount rate used to discount the value of damages from future emissions (SCC at 5, 3, 2.5 percent) is
  used to calculate net present value of SCC for internal consistency. This table shows monetized CO2 co-
  benefits at discount rates of 3 and 7 percent that were calculated using the global average SCC estimate at a
  3 percent discount rate because the interagency workgroup on this topic deemed this marginal value to be the
  central value. In the RIA, we also provide the monetized CO2 co-benefits using discount rates of 5 percent
  (average), 2.5 percent (average), and 3 percent (95th percentile).

    These co-benefits estimates represent the total monetized human
health benefits for populations exposed to less PM2.5 in
2013 from emission reductions due to the decreased electricity demand.
These co-estimates are calculated as the sum of the monetized value of
avoided premature mortality and morbidity associated with reducing a
ton of PM2.5 precursor emissions. To estimate the human
health benefits derived from reducing PM2.5 precursor
emissions, we used the general approach and methodology laid out in
Fann, Fulcher, and Hubbell (2009).\i\
---------------------------------------------------------------------------

    \i\ Fann, N., C.M. Fulcher, B.J. Hubbell. 2009. ``The influence
of location, source, and emissions type in estimates of the human
health benefits of reducing a ton of air pollution.'' Air Qual Atmos
Health (2009) 2:169-176.
---------------------------------------------------------------------------

    To generate the benefit-per-ton estimates, we used a model to
convert emissions of direct PM2.5 and PM2.5
precursors into changes in ambient PM2.5 levels and another
model to estimate the changes in human health associated with that
change in air quality. The PM2.5 benefit-per-ton estimates
used for this rule assume a certain geographic distribution of
emissions reductions, population density, meteorology, exposure and
baseline health incidence rates. To the extent that these attributes
differ greatly from those of the Mercury Chlor Alkali facilities, the
use of these $/ton values in combination with emission changes at MCL
facilities to estimate PM2.5 co-benefits may lead to higher
or lower benefit estimates than if these co-benefits were estimated
using site-specific data. Finally, the monetized health co-benefits
were divided by the emissions reductions to create the benefit-per-ton
estimates. These models assume that all fine particles, regardless of
their chemical composition, are equally potent in causing premature
mortality because there is no clear scientific evidence that would
support the development of differential effects estimates by particle
type.
    Direct PM is the only PM2.5 precursor we are estimating
for the non-mercury technology option. For context, it is important to
note that the magnitude of the PM co-benefits is largely driven by the
concentration response function for premature mortality. Experts have
advised EPA to consider a variety of assumptions, including estimates
based both on empirical (epidemiological) studies and judgments
elicited from scientific experts, to characterize the uncertainty in
the relationship between PM2.5 concentrations and premature
mortality. For this non-mercury technology option we cite two key
empirical studies, one based on the American Cancer Society cohort
study \j\ and the extended Six Cities cohort study.\k\ In the RIA for
this non-mercury technology option, which is available in the docket,
we also include co-benefits estimates derived from expert judgments and
other assumptions.
---------------------------------------------------------------------------

    \j\ Pope et al, 2002. ``Lung Cancer, Cardiopulmonary Mortality,
and Long-term Exposure to Fine Particulate Air Pollution.'' Journal
of the American Medical Association 287:1132-1141.
    \k\ Laden et al, 2006. ``Reduction in Fine Particulate Air
Pollution and Mortality.'' American Journal of Respiratory and
Critical Care Medicine. 173: 667-672.
---------------------------------------------------------------------------

    EPA strives to use the best available science to support our
benefits analyses. We recognize that interpretation of the science
regarding air pollution and health is dynamic and evolving. After
reviewing the scientific literature and recent scientific advice, we
have determined that the no-threshold model is the most appropriate
model for assessing the mortality benefits associated with reducing
PM2.5 exposure. Consistent with this recent advice, we are
replacing the previous threshold sensitivity analysis with a new
``Lowest Measured Level'' (LML) assessment. While a LML assessment
provides some insight into the level of uncertainty in the estimated PM
mortality benefits, EPA does not view the LML as a threshold and
continues to quantify PM-related mortality impacts using a full range
of modeled air quality concentrations.
    Most of the estimated PM-related benefits in this non-mercury
technology option would accrue to populations exposed to higher levels
of PM2.5. Using the Pope et al. (2002) study, 85 percent of
the population is exposed at or above the LML of 7.5 [mu]g/m\3\. Using
the Laden et al. (2006) study, 40 percent of the population is exposed
above the LML of 10 [mu]g/m\3\. It is important to emphasize that we
have high confidence in PM2.5-related effects down to the
lowest LML of the major cohort studies. This fact is important, because
as we estimate PM-related mortality among populations exposed to levels
of PM2.5 that are successively lower, our confidence in the
results diminishes. However, our analysis shows that the great majority
of the impacts occur at higher exposures. This analysis does not
include the type of detailed uncertainty assessment found in the 2006
PM2.5 National Ambient Air Quality Standard (NAAQS)
Regulatory Impact Analysis (RIA) because we lack the necessary air
quality input and monitoring data to run the benefits model. In
addition, we have not conducted any air quality modeling for this rule.
The 2006 PM2.5 NAAQS benefits analysis \l\ provides an
indication of the sensitivity of our results to various assumptions.
---------------------------------------------------------------------------

    \l\ U.S. Environmental Protection Agency, 2006. Final Regulatory
Impact Analysis: PM2.5 NAAQS. Prepared by Office of Air
and Radiation. October. Available on the Internet at http://www.epa.gov/ttn/ecas/ria.html.
---------------------------------------------------------------------------

    It should be emphasized that the monetized co-benefits estimates
provided above do not include benefits from several important benefit
categories, including reducing HAP

emissions, ecosystem effects, and visibility impairment. The primary
benefit of this non-mercury technology option is the reduction of
mercury emissions from these sources. Due to data and resource
limitations, we were unable to model mercury dispersion, deposition,
methylation, bioaccumulation in fish tissue, and human consumption of
mercury-contaminated fish that would be needed in order to estimate the
human health benefits from reducing mercury emissions. Although we do
not have sufficient information or modeling available to provide
monetized estimates for this non-mercury technology option, we include
a qualitative assessment of these other effects in the RIA for the non-
mercury technology option, which is available in the docket.
    The annualized social costs of this non-mercury technology option
are estimated to be $13 million (2007$, 7 percent discount rate) in
2013. The combined monetized energy co-benefits are $22 million to $43
million (2007$, 3 percent discount rate) and $21 million to $40 million
(2007$, 7 percent discount rate) for 2013. Thus, net benefits of the
non-mercury technology option are estimated at $9 million to $30
million (2007$, 3 percent discount rate) and $8 million to $27 million
(2007$, 7 percent discount rate) in 2013. EPA believes that the non-
monetized mercury benefits and the energy co-benefits of the non-
mercury technology option are likely to exceed the costs even when
taking into account the uncertainties in the cost and benefit
estimates.
4. Rationale for Selection of the Non-Mercury Technology Option
    While the results of these additional analyses were that the costs
and cost-effectiveness values decreased from those estimated in our
2008 analysis, there is still some uncertainty regarding numerous
facets of the cost analysis. Since the lower estimates of potential
costs show that conversion to non-mercury technology may be a
reasonable investment action in the long term, we are proposing this
supplemental amendment to request a complete set of comments on the
costs presented here in order to prepare a final cost analysis to
support or not support the non-mercury technology option. Once all
comments are received, we will re-evaluate whether or not these costs
constitute an unreasonably high cost impact given the benefits of
eliminating all mercury emissions to public health, the environment,
and to energy use.
    We gave serious consideration to the comments we received that
stated the use of mercury in chlor-alkali plants is unnecessary since
over 95 percent of the chlorine produced in the U.S. is already
produced using mercury-free technology. Forcing these plants to switch
to mercury-free technology would eliminate approximately 0.5 tons of
mercury released per year.
    In the 2008 proposal, we rejected the conversion to non-mercury
technology as a beyond-the floor option because of the high cost
impacts. The total annual costs estimated at that time were around $38
million, or around $7.5 million per facility on average for each of the
five facilities operating at that time. The revised cost analysis
described above estimates total annual costs of around $13 million,
which averages to just over $3 million per facility. Therefore, the
current estimated conversion costs are around 60 percent lower than
those driving our decision in 2008.
    With regard to cost-effectiveness, we stated in the original
proposal of the Mercury Cell NESHAP Standard in 2002 (67 FR 44683) that
we considered the additional mercury emission reduction achieved by the
beyond-the-floor option for hydrogen by-product vents and end-box
ventilation systems to be warranted at an incremental cost-
effectiveness of $9,000 per pound of mercury emission reduction. We did
not indicate that this cost-effectiveness level represented an upper
end of acceptability, and in other contexts, such as the Clean Air
Mercury Rule (70 FR 28606, 05/18/2005),\m\ we have found even larger
cost-effectiveness factors to be reasonable. Similarly, in our 2008
proposal of amendments, we did not conclude that a cost-effectiveness
value of $14,000 per pound of mercury emission reduction was
unacceptable, as this was one of several cost and economic factors
considered that led to our conclusion regarding the high cost impact of
the beyond-the-floor option of forced conversion.
---------------------------------------------------------------------------

    \m\ On March 29, 2005, EPA published a final rule (70 FR 15994)
entitled ``Revision of December 2000 Regulatory Finding on the
Emissions of Hazardous Air Pollutants From Electric Utility Steam
Generating Units and the Removal of Coal- and Oil-Fired Electric
Utility Steam Generating Units from the Section 112(c) List (Section
112(n) Revision Rule).'' Following that final action, the
Administrator received two petitions for reconsideration. In
response to those petitions, EPA announced (Federal Register, Vol.
70, October 28, 2005, p. 62200) the reconsideration of certain
aspects of the Section 112(n) Revision Rule, but these aspects did
not include costs related to mercury control or cost-effectiveness.
---------------------------------------------------------------------------

    Historically, EPA has not established a clear cost-effectiveness
level for mercury reductions that are considered acceptable. In fact,
we have rejected regulatory alternatives for mercury with cost-
effectiveness values of $5,000 per pound, and accepted regulatory
strategies with estimated cost-effectiveness values of $39,000 per
pound, in the case of the Clean Air Mercury Rule.\n\ Obviously, when
making decisions regarding regulatory approaches to achieve mercury
reductions, we have looked at cost in conjunction with many other
factors to assess the reasonableness of possible control strategies.
---------------------------------------------------------------------------

    \n\ The costs of complying with CAMR as a whole are discussed
briefly in the preamble to the final rule [Federal Register, Vol.
70, No. 95, May 18, 2005, pp. 28606-28700. Standards of Performance
for New and Existing Stationary Sources: Electric Utility Steam
Generating Units (40 CFR Parts 60, 72, and 75)], and in more detail
in two items in the two air dockets for the CAMR rule: EPA Office of
Research and Development's White Papers ``Control of Mercury
Emissions from Coal Fired Electric Utility Boilers.'' Docket ID No.
OAR-2002-0056 and Docket ID No. A-92-55.
---------------------------------------------------------------------------

    We also recognize that the mercury cell technology is an outdated
technology that has been largely phased out in the U.S. even without a
mercury emissions prohibition and even with the high costs of the
conversion process. While the economic analysis suggests significant
adverse economic impacts could occur if all four plants closed rather
than convert to non-mercury technology, we believe that it is possible
that one potential outcome of this proposed rule is that some companies
will convert rather than close, if the recent incidence of conversion
to non-mercury technology by the U.S. chlor-alkali industry continues.
Therefore, the negative economic effects described above would be
mitigated if only some of the four facilities closed.
    We also believe that any near-term negative economic impacts are
justified given the potential adverse health and environmental effects
of mercury that will be reduced permanently into the future. Therefore,
we are proposing this non-mercury technology option to request comments
on whether the benefits of eliminating mercury emissions from this
industry, as a beyond-the-floor control alternative, are warranted
given the foregoing discussion.

B. What is the enhanced work practices option (Option 2)?

1. Summary of Enhanced Work Practices Option
    On June 11, 2008 (73 FR 33257), we proposed modifications to the
work practice standards that apply to fugitive emissions, primarily
those fugitive emissions from cell rooms. The proposed modifications to
these work practices included requiring mercury

monitoring in the cell room for all facilities, along with daily work
practices and weekly certification of the performance of these work
practices. Establishment of the ``action level'' for investigating and
correcting high mercury concentration levels revealed by the continuous
monitors would be done for a minimum of 14 days and up to 30 days, at
least every 6 months, and the action level would be set at the 90th
percentile of the data acquired during the re-setting time period(s).
We also proposed to require mercury thermal recovery units that
continue to operate at closed or converted plants to remain subject to
the applicable requirements as long as they are in operation. These
amendments are discussed in more detail in the 2008 proposal (73 FR
33271-33272 and 33275).
    In this action, we are re-proposing these amendments as Option 2.
We received comments on these proposed amendments in 2008. In
developing our final action for the Mercury Cell NESHAP, we will
consider these previously submitted comments, along with any additional
comments received on this option as a result of this proposed action.
2. Estimated Impacts of the Enhanced Work Practices Option
a. Environmental and Energy Impacts
    The mercury emissions reported to the TRI for 2008 for the four
operating plants represent an 88 percent decrease from the pre-MACT
levels. While some of this reduction is a result of the ability to
estimate emission levels using the measured concentrations from the
cell room continuous mercury monitoring systems and calculated flow
rates, they are also a result of impacts of the Mercury Cell NESHAP. We
do not believe that there will initially be substantial emission
reductions associated with the enhanced work practice option. However,
we believe that as these plants increase their knowledge of the causes
of fugitive mercury emissions in the cell room through operation of the
cell room monitoring program, mercury emissions will continue to
steadily decrease. This is illustrated by the fact that the three
plants utilizing these systems reported a decrease in mercury emissions
of over 20 percent between 2007 and 2008. While this rate of decrease
is not likely to occur every year, we believe the fugitive mercury
emissions will continue to be reduced.
    Since the enhanced monitoring option will not change the basic
operation of the mercury cells, we do not anticipate that there will be
any energy impacts.
b. Cost and Economic Impacts
    The enhanced monitoring option would make the cell room monitoring
program mandatory for all mercury cell chlor-alkali plants and would
potentially impact all currently operating plants. However, the level
of these impacts will vary depending on whether a plant previously
elected to purchase and install a continuous mercury monitoring system
in its cell room to comply with the cell room monitoring program
alternative of the 2003 Mercury Cell NESHAP. For the three plants that
are currently complying via the cell room monitoring program
alternative option, we do not predict that there would be any cost
impacts. For the single plant that has elected not to purchase,
install, and operate a cell room monitoring system to comply via the
cell room monitoring program alternative, we estimate that it would
incur a capital cost for a monitoring system of around $120,000, and
that the total annual cost (including annualized capital cost and
operation and maintenance costs) would be slightly more than $25,000
per year. We believe that this value is a low percentage of the annual
revenues for this facility and would not cause any adverse economic
impacts. The cost and economic impacts of the enhanced monitoring
option were discussed in more detail in the 2008 proposal (73 FR
33276).
3. Rationale for Selection of the Enhanced Work Practices Option
    The evidence is clear that the continuous mercury monitoring
programs are effective in identifying and correcting emission events.
It is also evident that they are beneficial in identifying emission
sources that may have previously been undetected. However, we believe
that the routine work practices also play an important role in reducing
emissions, by avoiding situations where elevated mercury concentrations
are detected by the monitoring program. We believe that the cost and
economic impacts of requiring both the work practices and the
monitoring program are justified, given the effectiveness this
combination has in reducing mercury emissions. Further, we believe that
selection of this option would lessen the potential near-term negative
economic impacts associated with the non-mercury technology option,
since plants would likely continue to operate.

C. What amendments are being proposed that are independent of which
option is selected?

    In addition to the co-proposal of the two options discussed above
in Sections III.A and III.B, we are also proposing amendments that
would apply regardless of whether we select the non-mercury technology
option or the enhanced monitoring option. Specifically, we are
proposing to amend the provisions of the existing NESHAP that apply to
periods of SSM and to correct compliance errors in the rule.
1. Provisions That Apply During Periods of Startup, Shutdown, and
Malfunction
    This proposed action would amend the provisions of the existing
NESHAP that apply to periods of SSM. The proposed revisions of these
provisions result from a Court decision that vacated portions of two
provisions in EPA's CAA section 112 regulations governing the emissions
of HAP during periods of SSM. (Sierra Club v. EPA, 551 F.3d 1019 (DC
Cir. 2008), cert. denied, 130 S. CT. 1735 (U.S. 2010)). Consequently,
this proposed revised rule would require that affected sources comply
with the emission limitations and work practices at all times,
including during periods of SSM. For reasons discussed below, we are
also proposing to promulgate an affirmative defense to civil penalties
for exceedances of emission standards caused by malfunctions, as well
as criteria for establishing the affirmative defense. These changes
would go into effect upon the effective date of promulgation of the
final rule.
    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 SSM.
Sierra Club v. EPA, 551 F.3d 1019 (DC Cir. 2008), cert. denied, 130 S.
Ct. 1735 (2010). Specifically, the Court vacated the SSM exemption
contained in 40 CFR 63.6(f)(1) and (h)(1), that is part of a regulation
commonly known as the ``General Provisions Rule,'' that EPA had
promulgated under section 112 of the CAA. When incorporated into CAA
section 112(d) regulations for specific source categories, these two
provisions exempted sources from the requirement to comply with the
otherwise applicable CAA section 112(d) emission standard during
periods of SSM. The 2003 Mercury Cell NESHAP Subpart included a
reference to 40 CFR 63.6(f)(1), as well as regulatory text unique to
the 2003 Mercury Cell NESHAP that exempted compliance with standards
during SSM events. It

did not include a reference to 40 CFR 63.6 (h)(1), since the rule does
not have opacity and visible emission standards. In light of Sierra
Club v. EPA, we are proposing to eliminate the SSM exemption in the
Mercury Cell NESHAP, by revising Table 10, which addresses the
applicability of the part 63 General Provisions to mercury cell chlor-
alkali plants, to state that 40 CFR 63.6(f)(1) does not apply. As such,
all emission standards and work practices would apply at all times. We
are also proposing to remove other references in subpart IIIII and
Table 10 related to SSM, including provisions that exempted compliance
with standards during SSM periods. We are also proposing to remove the
General Provisions' requirement that the source develop an SSM plan,
and to remove certain recordkeeping and reporting requirements related
to the SSM exemption, but we are retaining the recordkeeping and
related requirements for malfunctions and request public comment on the
requirements. EPA has attempted to ensure that regulatory language
relating to the SSM exemption has been removed. We solicit comment on
whether we have overlooked any regulatory provisions that might be
inappropriate, unnecessary, or redundant based on our proposal to
remove the exemption from compliance with emission standards during
periods of SSM.
    Regarding startup and shutdown modes of operation at mercury cell
plants, based on available information EPA does not consider emissions
during these periods to be significantly different than emissions
during normal operation, and therefore is not proposing separate limits
that would apply during these periods. We do not have any information
that shows emissions at mercury cell plants would be significantly
different during startup or shutdown than during normal operation; nor
do we have information suggesting that the emissions control measures
required by the 2003 rule would be less effective during startup or
shutdown periods. We request public comment on whether emissions during
startup and shutdown are instead significantly different compared to
other normal operation, such that a different standard for startup and
shutdown periods would be warranted.
    Periods of startup, normal operations, and shutdown are all
predictable and routine aspects of a source's operations. In 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 useful manner
* * *'' (40 CFR 63.2). EPA believes that a malfunction should not be
viewed as a distinct operating mode and, therefore, any emissions that
occur during malfunctions do not need to be factored into development
of CAA section 112(d) standards, which, once promulgated, apply at all
times. In Mossville Environmental Action Now v. EPA, 370 F.3d 1232,
1242 (DC Cir. 2004), the court upheld as reasonable standards that had
factored in variability of emissions under all operating conditions.
However, nothing in section 112(d) or in case law requires that EPA
anticipate and account for the innumerable types of potential
malfunction events in setting emission standards. See, Weyerhaeuser v.
Costle, 590 F.2d 1011, 1058 (DC Cir. 1978) (``In the nature of things,
no general limit, individual permit, or even any upset provision can
anticipate all upset situations. After a certain point, the
transgression of regulatory limits caused by ``uncontrollable acts of
third parties, such as strikes, sabotage, operator intoxication or
insanity, and a variety of other eventualities, must be a matter for
the administrative exercise of case-by-case enforcement discretion, not
for specification in advance by regulation.'') Further, it is
reasonable to interpret CAA section 112(d) as not requiring EPA to
account for malfunctions in setting emission standards. For example, we
note that CAA section 112 uses the concept of ``best performing''
sources to define 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. Consequently, MACT 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 into account
malfunctions in setting CAA section 112(d) standards. 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
each source category. Moreover, malfunctions can vary in frequency,
degree, and duration, further complicating standard setting.
    Under this proposal, 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.)
    Finally, EPA recognizes that even equipment that is properly
designed and maintained can sometimes fail and that such failure can
sometimes cause or contribute to an exceedance of the relevant emission
standard. (See, e.g., State Implementation Plans: Policy Regarding
Excessive Emissions During Malfunctions, Startup, and Shutdown (Sept.
20, 1999); Policy on Excess Emissions During Startup, Shutdown,
Maintenance, and Malfunctions (Feb. 15, 1983).) Therefore, consistent
with our recently promulgated final amendments to regulations
addressing the Portland Cement category (75 FR 54970, Sept. 9, 2010),
we are proposing to add regulatory language providing an affirmative
defense against civil penalties for exceedances of emission limits that
are caused by malfunctions. See proposed amendment to 40 CFR 63.8266
(defining ``affirmative defense'' to mean, in the context of an
enforcement proceeding, a response or defense put forward by a
defendant, regarding which the defendant has the burden of proof, and
the merits of which are independently and objectively evaluated in a
judicial or administrative proceeding). We are also proposing
regulatory provisions to specify the elements that are necessary to
establish this affirmative defense; the source would have to prove by a
preponderance of the evidence that it has met all of the elements set
forth in sections. (See proposed amendment to 40 CFR 63.8226(b); see
also 40 CFR 22.24.) The proposed criteria would ensure that the
affirmative defense is available only where the event that causes an
exceedance of the emission limit meets the narrow definition of
malfunction in 40 CFR 63.2 (sudden, infrequent, not reasonable
preventable and not caused by poor maintenance and/or careless
operation). The proposed criteria also are designed to ensure that
steps are taken to correct the malfunction, to minimize emissions, and
to prevent future malfunctions. In

any judicial or administrative proceeding, the Administrator would be
able to challenge the assertion of the affirmative defense and, if the
respondent has not met its burden of proving all of the requirements in
the affirmative defense, appropriate penalties could be assessed in
accordance with Section 113 of the Clean Air Act (see also 40 CFR
22.77).
2. Compliance Provisions Rule Corrections
    We are proposing amendments to correct errors and improve the
compliance provisions of the rule. These changes, which are described
below, were included in the June 2008 proposal (73 FR 33275).
a. Detection Limit For Mercury Monitor Analyzers
    Paragraph (a)(2) of Sec.  63.8242, ``What are the installation,
operation, and maintenance requirements for my continuous monitoring
systems?'' requires that mercury continuous monitor analyzers have a
detector with the capability to detect a mercury concentration at or
below 0.5 times the mercury concentration level measured during the
performance test. Since promulgation of the 2003 Mercury Cell NESHAP,
we determined that setting the analyzer detection capability in
reference to the concentration level during the performance test could
be problematic. We realized that a concentration of 0.5 times the
mercury concentration could, in cases of low mercury concentrations, be
infeasible for the monitoring devices on the market. Information
available to us at this time shows that 0.1 micrograms per cubic meter
([mu]g/m3) is the detection limit of commonly commercially
available analyzers. We believe that analyzers with detection limits at
this level are more than sufficient to determine compliance with the
limitations in the 2003 Mercury Cell NESHAP. Therefore, we are
proposing to revise this paragraph to require a detector with the
capability to detect a mercury concentration at or below 0.5 times the
mercury concentration measured during the test or 0.1 [mu]g/
m3.
b. Averaging Period for Mercury Recovery Unit Compliance
    The 2003 Mercury Cell NESHAP is inconsistent as to whether the rule
requires a daily average or an hourly average to determine continuous
compliance with the emissions standard for mercury recovery units found
at Sec.  63.8190(a)(3) of Sec.  63.8190 ``What emission limitations
must I meet?'' Paragraph (b) of Sec.  63.8243 ``What equations and
procedures must I use to demonstrate continuous compliance?'' clearly
indicates that this averaging period is daily: ``You must calculate the
daily average mercury concentration using Equation 2 * * *'' However,
paragraph (b) of Sec.  63.8246 ``How do I demonstrate continuous
compliance with the emission limitations and work practice standards?''
states that for each mercury thermal recovery unit vent, ``you must
demonstrate continuous compliance with the applicable emission limit
specified in Sec.  63.8190(a)(3) by maintaining the outlet mercury
hourly-average concentration no higher than the applicable limit.''
    It was our intention for compliance to be based on a daily average,
as detailed below, and the inclusion of ``hourly'' in paragraph (b) of
Sec.  63.8246 ``How do I demonstrate continuous compliance with the
emission limitations and work practice standards?'' was a drafting
error. Therefore, we are proposing to correct this error by replacing
``hourly'' in Sec.  63.8246(b) with ``daily.'' In the proposal Federal
Register notice for the 2003 Mercury Cell NESHAP (67 FR 44678, July 3,
2002), we clearly stated our intention when we summarized the
requirements as follows:

    ``To continuously comply with the emission limit for each by-
product hydrogen stream, end-box ventilation system vent, and
mercury thermal recovery unit, we are proposing that each owner and
operator would continuously monitor outlet elemental mercury
concentration and compare the daily average results with a mercury
concentration operating limit for the vent. * * *''
    ``Continuous compliance would be demonstrated by collecting
outlet elemental mercury concentration data using continuous mercury
vapor monitor, calculating daily averages, and documenting that the
calculated daily average values are no higher than established
operating limits. Each daily average vent elemental mercury
concentration greater than the established operating limit would be
considered a deviation.

IV. Request for Comment

    We request comment on all aspects of the proposed action. All
significant comments received during the comment period will be
considered.
    Five comments were received on the amendments proposed in June
2008. These commenters represent one environmental organization, one
industry trade organization, and two companies that own and operate
mercury cell chlor-alkali plants. The fifth comment was anonymously
submitted in support of environmental organizations. We reviewed and
considered these comments. As discussed above in section II.C.3 of this
preamble, the consideration of one of the issues raised in the comments
has caused us to publish this supplemental proposal today proposing the
non-mercury technology option. In developing our final action, we will
consider all previously-submitted relevant comments in addition to any
comments submitted in response to today's proposal.
    Comments are requested on several aspects of this proposed action.
First, we are soliciting comments on which of the two options (Option
1: Non-Mercury Technology or Option 2: Enhanced Work Practices) is most
appropriate. In providing comments on the selection of one of these
options, please provide detailed rationale and additional technical
information that supports your recommendation.
    Second, we are requesting comments on the specific amendments being
proposed under both options. After making a decision on which option we
will select for promulgation, we will consider and address all
significant comments received on the amendments related to that option.
We received comments on the enhanced work practices option following
the proposal in June 2008. If that option is selected, we will consider
and address those comments along with any new comments received.
    Third, we are specifically requesting comments on the potential for
the elimination of mercury emissions without converting to membrane
cells or plant closure. We are also requesting comment on any measures
beyond those included in the enhanced monitoring option that might be
employed at mercury cell facilities which could achieve even greater
reductions such that mercury emissions are at ``near zero'' levels
without conversion to a non-mercury process or closure.
    As noted earlier, we believe that it is improbable that a mercury
cell chlor-alkali plant can be operated without mercury emissions.
Therefore, we have assumed that requiring the elimination of mercury
emissions would effectively require existing mercury cell chlor-alkali
plants either to convert to a non-mercury technology or to cease
production of chlorine with their current mercury cell production
methods. However, if there are circumstances where the elimination of
mercury emissions from an operating mercury cell plant could be
achieved, we are specifically interested in data and supporting
information regarding technologies that would eliminate mercury
emissions from an operating mercury cell facility.

    We are also interested in the possibility of other emission
reduction technologies, process modifications, or practices not
included in the enhanced work practices option that could reduce
mercury emissions to ``near-zero'' levels. We are aware of the
significant efforts that have been made by the four currently operating
mercury cell facilities to reduce mercury emissions. As some of these
efforts have been developed more fully in recent years, we have seen
significant and consistent reductions in emissions to the current
levels. We believe that the further refinement of these methods would
continue to steadily decrease mercury emissions. We are requesting
comment on a realistic lower bound level that could be achieved.
    In addition, a near-zero emission standard alternative would need
to include appropriate testing and monitoring provisions. Therefore, in
addition to information regarding a realistic lower-bound emissions
level, we are also requesting comment on methods to overcome the
difficulty of accurately measuring cell room fugitive emissions.
    Fourth, we are requesting comments on the proposed amendments
related to provisions that apply during periods of SSM and the
compliance provisions rule corrections. These amendments would apply
regardless of which option we select. The compliance provisions rule
corrections were also proposed in June 2008, and any comments received
on the prior proposal related to these amendments will also be
considered and addressed.
    Finally, comments were provided in 2008 on all the reconsideration
decisions discussed in our June 2008 proposal (and summarized in
section II.C of this preamble). We will accept additional comments on
these decisions and consider them, along with the previous comments, in
making our final decisions.

VII. Statutory and Executive Order Reviews

A. Executive Order 12866: Regulatory Planning and Review

    Under section 3(f)(1) of Executive Order 12866 (58 FR 51735,
October 4, 1993), this action is an ``economically significant
regulatory action'' because Option 1 is likely to have an annual effect
on the economy of $100 million or more. Accordingly, EPA submitted this
action to the Office of Management and Budget (OMB) for review under EO
12866 and any changes made in response to OMB recommendations have been
documented in the docket for this action. In addition, EPA prepared a
RIA of the potential costs and benefits associated with this action.
    When estimating the PM2.5-related human health benefits
and compliance costs in Table 2 of this preamble, EPA applied methods
and assumptions consistent with the state-of-the-science for human
health impact assessment, economics and air quality analysis. EPA
applied its best professional judgment in performing this analysis and
believes that these estimates provide a reasonable indication of the
expected benefits and costs to the nation of this rulemaking. The RIA
available in the docket describes in detail the empirical basis for
EPA's assumptions and characterizes the various sources of
uncertainties affecting the estimates below.
    When characterizing uncertainty in the PM-mortality relationship,
EPA has historically presented a sensitivity analysis applying
alternate assumed thresholds in the PM concentration-response
relationship. In its synthesis of the current state of the PM science,
EPA's 2009 Integrated Science Assessment for Particulate Matter
concluded that a no-threshold log-linear model most adequately portrays
the PM-mortality concentration-response relationship. In the RIA
accompanying this rulemaking, rather than segmenting out impacts
predicted to be associated levels above and below a ``bright line''
threshold, EPA includes a LML that illustrates the increasing
uncertainty that characterizes exposure attributed to levels of
PM2.5 below the LML for each study. Figures provided in the
RIA show the distribution of baseline exposure to PM2.5, as
well as the lowest air quality levels measured in each of the
epidemiology cohort studies. This information provides a context for
considering the likely portion of PM-related mortality benefits
occurring above or below the LML of each study; in general, our
confidence in the size of the estimated reduction PM2.5-
related premature mortality diminishes as baseline concentrations of
PM2.5 are lowered. Using the Pope et al. (2002) study, the
85 percent of the population is exposed at or above the LML of 7.5
[micro]g/m\3\. Using the Laden et al. (2006) study, 40 percent of the
population is exposed above the LML of 10 [micro]g/m\3\. While the LML
analysis provides some insight into the level of uncertainty in the
estimated PM mortality benefits, EPA does not view the LML as a
threshold and continues to quantify PM-related mortality impacts using
a full range of modeled air quality concentrations.
    The cost analysis is also subject to uncertainties. Estimating the
cost conversion from one process to another is more difficult than
estimating the cost of adding control equipment because it is more
dependent on plant specific information. The estimation of cost savings
from environmental compliance cost savings elimination of the mercury
process is also uncertain. The numbers were based on the savings
reported by one U.S. facility and some studies from outside the U.S.
The savings might be greater or smaller than estimated. Likewise, since
the electricity savings are dependent on many of the same factors, they
are also uncertain and may be greater or smaller than estimated.
    A summary of the monetized benefits, social costs, and net benefits
for the two options at discount rates of 3 percent and 7 percent is in
Table 2 of this preamble.
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    For more information on the benefits analysis, please refer to the
RIA for this rulemaking, which is available in the docket.

B. Paperwork Reduction Act

    The information collection requirements in this proposed rule, have
been submitted for approval to OMB under the Paperwork Reduction Act,
44 U.S.C. 3501 et seq. The information collection request (ICR)
document prepared by EPA has been assigned an EPA ICR number 2046.06.
    OMB has previously approved the information collection requirements
in the existing regulation (40 CFR part 63, subpart IIIII) under the
provisions of the Paperwork Reduction Act, 44 U.S.C. 3501 et seq. and
has assigned OMB control number 2060-0542. The OMB control numbers for
EPA's regulations in 40 CFR are listed in 40 CFR part 9.
    The proposed amendments under Option 1 would result in changes to
the information collection requirements in the regulation. This
information is being collected to assure that mercury emissions have
been eliminated. The required notifications, reports, and records are
essential in determining compliance, and are required of all affected
facilities. The recordkeeping and reporting requirements in this
proposed rule are based on the requirements in EPA's NESHAP General
Provisions (40 CFR part 63, subpart A). The recordkeeping and reporting
requirements in the General Provisions are mandatory pursuant to
section 114 of the CAA (42 U.S.C. 7414). All information other than
emissions data submitted to EPA pursuant to the information collection
requirements for which a claim of confidentiality is made is
safeguarded according to CAA section 114(c) and the Agency's
implementing regulations at 40 CFR part 2, subpart B.
    The only information collection associated with the proposed
amendments under Option 1 is a one-time certification that must be
submitted 60 days after the compliance date. It is estimated that the
burden for this information collection is 3 labor hours per response
per facility, for a total of 12 labor hours for all four facilities.
This burden will occur during the first year after promulgation, but
the annual burden for this information collection averaged over the 3
years following the compliance date of these amendments is estimated to
be a total of 4 labor hours per year. Burden is defined at 5 CFR
1320.3(b).
    These proposed amendments under Option 2 would result in changes to
the information collection requirements in the regulation. This
information is being collected to assure compliance with the
regulation. The required notifications, reports, and records are
essential in determining compliance, and are required of all affected
facilities. The recordkeeping and reporting requirements in proposed
option 2 are based on the requirements in EPA's NESHAP General
Provisions (40 CFR part 63, subpart A). The recordkeeping and reporting
requirements in the General Provisions are mandatory pursuant to
section 114 of the CAA (42 U.S.C. 7414). All information other than
emissions data submitted to EPA pursuant to the information collection
requirements for which a claim of confidentiality is made is
safeguarded according to CAA section 114(c) and the Agency's
implementing regulations at 40 CFR part 2, subpart B.
    The annual burden for this information collection averaged over the
three years following promulgation of these amendments is estimated to
be a total of 3,800 labor hours per year. The average annual reporting
burden is 16 hours per response, with approximately 3 responses per
facility for 5 respondents. The only capital/startup costs are
associated with the installation of a cell room monitoring system at
one facility, since we know that these systems are already in place at
the other four facilities. The total capital/startup cost annualized
over its expected useful life is $13,000. The total operation and
maintenance is $60,000 per year. There are no estimated costs
associated with purchase of services. Burden is defined at 5 CFR
1320.3(b).
    An agency may not conduct or sponsor, and a person is not required
to respond to, a collection of information unless it displays a
currently valid OMB control number. The OMB control numbers for 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, EPA has established a public docket for
this action, which includes this ICR, under Docket ID number EPA-HQ-
OAR-2002-0017. Submit any comments related to the ICR for this proposed
rule to EPA and OMB. See ADDRESSES section at the beginning of this
notice for where to submit comments to EPA. Send comments to OMB at the
Office of Information and Regulatory Affairs, Office of Management and
Budget, 725 17th Street NW., Washington, DC 20503, Attention: Desk
Office for EPA. Since OMB is required to make a decision concerning the
ICR between 30 and 60 days after March 14, 2011, a comment to OMB is
best assured of having its full effect if OMB receives it by April 13,
2011. The final rule will respond to any OMB or public comments on the
information collection requirements contained in these proposed
amendments.

C. Regulatory Flexibility Act

    The Regulatory Flexibility Act generally requires an agency to
prepare a regulatory flexibility analysis of any rule subject to notice
and comment rulemaking requirements under the Administrative Procedure
Act or any other statute unless the agency certifies that the rule
would not have a significant economic impact on a substantial number of
small entities. Small entities include small businesses, small not-for-
profit enterprises, and small governmental jurisdictions.
    For the purposes of assessing the impacts of this proposed rule on
small entities, small entity is defined as: (1) A small business that
meets the Small Business Administration size standards for small
businesses, as defined by the Small Business Administration's
regulations at 13 CFR 121.201; (2) a small governmental jurisdiction
that is a government of a city, county, town, school district, or
special district with a population of less than 50,000; and (3) a small
organization that is any not-for-profit enterprise which is
independently owned and operated and is not dominant in its field.
    After considering the economic impacts of this proposed rule on
small entities, I certify that this action will not have a significant
economic impact on a substantial number of small entities. This
proposed rule is estimated to impact a total of four sources, with one
of the four facilities estimated to be a small entity. We have
estimated that small entity compliance costs, as assessed by the
facilities' CSR, are expected to be just over 1 percent of revenues.
New sources are already prohibited from using the mercury technology in
the chlor-alkali production process by virtue of the 2003 Mercury Cell
NESHAP's provisions; consequently, we did not estimate any impacts for
new sources since this rulemaking would not impose any new requirements
on them.
    This proposed rule will not have a significant economic impact on a
substantial number of small entities, since there is only one small
entity in the group of four facilities and compliance costs for this
small entity are expected to be just over 1 percent of revenues.
However, we continue to be interested in the potential impacts of this
proposed action on small entities and welcome comments on issues
related to such impacts.

D. Unfunded Mandates Reform Act

    This action contains no Federal mandates under the regulatory
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 imposes no enforceable duty on any
State, local or Tribal governments or the private sector. (Note: The
term ``enforceable duty'' does not include duties and conditions in
voluntary Federal contracts for goods and services.) Therefore, this
action is not subject to the requirements of sections 202 and 205 of
the UMRA. This action also is not subject to the requirements of
section 203 of UMRA because it contains no regulatory requirements that
might significantly or uniquely affect small governments.

E. Executive Order 13132: Federalism

    Executive Order 13132 (64 FR 43255, August 10, 1999) requires EPA
to develop an accountable process to ensure ``meaningful and timely
input by State and local officials in the development of regulatory
policies that have federalism implications.'' ``Policies that have
federalism implications'' is defined in the Executive Order to include
regulations that have ``substantial direct effects on the States, on
the relationship between the national government and the States, or on
the distribution of power and responsibilities among the various levels
of government.''
    This action does not have federalism implications. It will not have
substantial direct effects on the States, on the relationship between
the national government and the States, or on the distribution of power
and responsibilities among the various levels of government, as
specified in Executive Order 13132. This proposed rule does not impose
any requirements on State and local governments. Thus, Executive Order
13132 does not apply to this action.
    In the spirit of Executive Order 13132, and consistent with EPA
policy to promote communications between EPA and State and local
governments, EPA specifically solicits comment on this proposed rule
from State and local officials.

F. Executive Order 13175: Consultation and Coordination with Indian
Tribal Governments

    This action does not have Tribal implications, as specified in
Executive Order 13175 (65 FR 67249, November 9, 2000). This proposed
rule imposes no requirements on Tribal governments. Thus, Executive
Order 13175 does not apply to this rule. EPA specifically solicits
additional comment on this proposed rule from Tribal officials.

G. Executive Order 13045: Protection of Children From Environmental
Health and Safety Risks

    EPA interprets Executive Order 13045 (62 FR 19885, April 23, 1997)
as applying to those regulatory actions that concern health or safety
risks, such that the analysis required under section 5-501 of the Order
has the potential to influence the regulation. This action is not
subject to Executive Order 13045 because it is based solely on
technology performance. However, given the potential health effects of
mercury on children, the elimination in mercury emissions from these
four facilities could result in additional protection of children from
environmental health risks.

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 in
Executive Order 13211, ``Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use'' (66 FR
28355, May 22, 2001) because it is not likely to have a significant
adverse effect on the supply, distribution, or use of energy. We have
concluded that this action is not likely to have any adverse energy
effects because no additional requirements are contained in this
proposed rule that consume energy. In fact, as discussed previously in
this preamble, this action would result in decreased energy usage.

I. National Technology Transfer and Advancement Act

    Section 12(d) of the National Technology Transfer and Advancement
Act of 1995 (``NTTAA''), Public Law 104-113 (15 U.S.C. 272 note)
directs EPA to use voluntary consensus standards in its regulatory
activities unless to do so would be inconsistent with applicable law or
otherwise impractical. Voluntary consensus standards are technical
standards (e.g., materials specifications, test methods, sampling
procedures, and business practices) that are developed or adopted by
voluntary consensus standards bodies. NTTAA directs EPA to provide
Congress, through OMB, explanations when the Agency decides not to use
available and applicable voluntary consensus standards.
    This proposed rulemaking does not involve technical standards.
Therefore, EPA is not considering the use of any voluntary consensus
standards.

J. Executive Order 12898: Federal Actions To Address Environmental
Justice in Minority Populations and Low-Income Populations

    Executive Order 12898 (59 FR 7629, February 16, 1994) establishes
Federal executive policy on environmental justice. Its main provision
directs Federal agencies, to the greatest extent practicable and
permitted by law, to make environmental justice part of their mission
by identifying and addressing, as appropriate, disproportionately high
and adverse human health or environmental effects of their programs,
policies, and activities on minority populations and low-income
populations in the U.S.
    EPA has determined that this proposed rule will not have
disproportionately high and adverse human health or environmental
effects on minority or low-income populations because it increases the
level of environmental protection for all affected populations without
having any disproportionately high and adverse human health or
environmental effects on any population, including any minority or low-
income population. The nationwide standards would totally eliminate
mercury emissions from sources affected by this proposed rule and thus
eliminate all adverse human health or environmental effects on all
populations, including minority or low-income populations.
    An analysis of demographic data showed that the average percentages
of the population below the poverty level and the percentages of the
population 17 years old and younger in populations in close proximity
to the sources are similar to the national averages. The percentage of
minorities in populations in close proximity to the sources is lower
than the national average.
    In determining the aggregate demographic makeup of the communities
near affected sources, EPA used census data at the block group level to
identify demographics of the populations considered to be living near
affected sources, such that they have notable exposures to current
emissions from these sources. In this approach, EPA reviewed the
distributions of different socio-demographic groups in the locations of
the expected emission reductions from this proposed rule. The review
identified those census block groups with centroids within a circular
distance of a 0.5, 3, and 5 miles of affected sources and determined
the demographic and socio-economic composition (e.g., race, income,

education, etc) of these census block groups. The radius of 3 miles (or
approximately 5 kilometers) has been used in other demographic analyses
focused on areas around potential sources.o p q r There were
no census block groups with centroids within 0.5 miles of any of the
sources affected by this proposed rule. EPA's demographic analysis has
shown that these areas in aggregate have lower proportions of American
Indians, African-Americans, Hispanics, and ``Other and Multi-racial''
populations than the national average. The analysis showed that these
areas in aggregated had similar proportions of families with incomes
below the poverty level as the national average.\s\
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    \o\ U.S. GAO (Government Accountability Office). Demographics of
People Living Near Waste Facilities. Washington, DC: Government
Printing Office; 1995.
    \p\ Mohai P, Saha R. ``Reassessing Racial and Socio-economic
Disparities in Environmental Justice Research''. Demography.
2006;43(2): 383-399.
    \q\ Mennis J. ``Using Geographic Information Systems to Create
and Analyze Statistical Surfaces of Populations and Risk for
Environmental Justice Analysis''. Social Science Quarterly,
2002;83(1):281-297.
    \r\ Bullard RD, Mohai P, Wright B, Saha R, et al. Toxic Waste
and Race at Twenty 1987-2007. United Church of Christ. March, 2007.
    \s\ The results of the demographic analysis are presented in
``Review of Environmental Justice Impacts,'' August 2010, a copy of
which is available in the docket.
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    EPA defines ``Environmental Justice'' to include meaningful